Jacob Bell
New Member
A Novel Role of Cannabinoids: Implication in the Fever Induced by Bacterial Lipopolysaccharide
Khalid Benamar,
Menachem Yondorf,
Joseph J. Meissler,
Ellen B. Geller,
Ronald J. Tallarida,
Toby K. Eisenstein and
Martin W. Adler
- Author Affiliations
Center for Substance Abuse Research (K.B., M.Y., E.B.G., M.W.A.) and Departments of Microbiology and Immunology (J.J.M., T.K.E.) and Pharmacology (R.J.T.), Temple University School of Medicine, Philadelphia, Pennsylvania
Address correspondence to:
Dr. Khalid Benamar, Center of Substance Abuse Research, Temple University School of Medicine, 3400 North Broad Street, Philadelphia, PA 19140. E-mail: kbenamar@temple.edu
Next Section
Abstract
There is continuing interest in elucidating the actions of drugs of abuse on the immune system and on infection. The present study investigated the effects of the cannabinoid (CB) receptor agonist aminoalkylindole, (+)-WIN 55,212-2 [(4,5-dihydro-2-methyl-4(4-morpholinylmethyl)-1-(1-naphthalenyl-carbonyl)-6H-pyrrolo[3,2,1ij]quinolin-6-one], on fever produced after injection of lipopolysaccharide (LPS), a component of the outer membrane of Gram-negative bacteria, the best known and most frequently used experimental model. Intraperitoneal injection of LPS (50 μg/kg) induced a biphasic fever, with the first peak at 180 min and the second at 300 min postinjection. Pretreatment with a nonhypothermic dose of the cannabinoid receptor agonist WIN 55,212-2 (0.5—1.5 mg/kg i.p.) antagonized the LPS-induced fever. However, pretreatment with the inactive enantiomer WIN 55,212-3 [1.5 mg/kg i.p.; S-(-)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthanlenyl)methanone mesylate] did not. The inhibitory effect of WIN 55,212-2 on LPS-induced fever was reversed by SR141716 [N-(piperdin-1-yl)-5-(4-chloropheny)-1-(2,4-dichloropheny)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride], a selective CB1 receptor antagonist, but not by SR144528 (N-[(1S)-endo-1,3,3-trimethylbicyclo[2.2.1]heptan-2-yl]5-(4-choro-3-methylphenyl)-1-(4-methylbenzyl)pyrazole-3-carboxamide), a selective antagonist at the CB2 receptor. The present results show that cannabinoids interact with systemic bacterial LPS injection and indicate a role of the CB1 receptor subtype in the pathogenesis of LPS fever.
Previous SectionNext Section
Fever is part of the acute-phase reaction to infection, characterized by a raised thermoregulatory set point, which leads to an elevation in body temperature (Tb). The systemic administration of LPS, a powerful activator of the innate immune system and the most commonly used experimental model for systemic infection, induces a variety of sickness-associated responses such as anorexia, increased slow-wave sleep (Hori et al., 1991; Elmquist et al., 1997), change in nociceptive threshold, and fever (Benamar et al., 2000, 2005; Abe et al., 2001). The fever due to LPS and other exogenous pyrogens is believed to be caused by the synthesis and release from monocytes and macrophages of a number of well characterized endogenous pyrogenic factors, including interleukin (IL)-1, IL-6, tumor necrosis factor (TNF)-α, and macrophage inflammatory protein-1 (Myers et al., 1994; Blatteis, 2006). In addition, it has been shown that the opioid system is involved in LPS-induced fever (Benamar et al., 2000, 2005) and that pretreatment with capsaicin, an agonist at the vanilloid receptor, blocks the first phase of LPS-induced fever (Dogen et al., 2004).
Cannabis and its derivative compounds, collectively known as cannabinoids, produce an array of pharmacological symptoms in animals and humans (Ovadia et al., 1995; Chaperon and Thiebot, 1999). Two subtypes of receptors, CB1 and CB2, mediate cannabinoid-induced effects (Howlett, 1995). The development of synthetic cannabinoid agonists has provided remarkable advances in cannabis research. One such ligand is the aminoalkylindole, (+)-WIN 55,212-2 [(4,5-dihydro-2-methyl-4(4-morpholinylmethyl)-1-(1-naphthalenyl-carbonyl)-6H-pyrrolo[3,2,1ij]quinolin-6-one], which displays high selectivity for cannabinoid receptors. Previous studies have demonstrated that WIN 55,212-2 is highly potent and efficacious in vivo and in vitro. WIN 55,212-2 prevents i.v. cocaine self-administration, increases tail-flick reflexes, exerts antihyperalgesic effects, and induces hypothermia in rats, indicating that WIN 55,212-2 is pharmacologically active in vivo (Fox et al., 2001). WIN 55,212-2 undergoes less nonspecific binding than classical cannabinoids and interacts negligibly with other neurotransmitter systems and ion channels (Jansen et al., 1992). In contrast, Δ9-tetrahydrocannabinol (Δ9-THC) has been reported to produce hypothermia by interacting with other neurotransmitters, including serotonin (Davies and Graham, 1980). One of the major advances in CB research has been the development of a potent and selective antagonist of the CB1 receptor, SR141716A. This compound was found to block the hypokinetic, hypothermic, cataleptic, and antinociceptive effects of Δ9-THC and WIN 55,212-2 in mice and rats (Rinaldi-Carmona et al., 1994; Reche et al., 1996). In addition, studies with SR141716 have provided evidence for the presence of CB1 receptors in peripheral tissues as well as in the central nervous system (Varga et al., 1995; Lake et al., 1997).
However, the CB2 receptor subtype has been defined as the peripheral CB receptor, primarily because CB2 mRNA expression has been detected mainly in cells of the immune system (Galieque et al., 1995). The CB2 is expressed inducibly and is present at high levels compared with the CB1 when microglia are in responsive and primed states of activation (Cabral and Marciano-Cabral, 2005). Like the CB1 receptor subtype, the CB2 receptor is a member of the G protein-coupled receptor family and on stimulation causes inhibition of adenylyl cyclase. A potent, selective, and orally active antagonist of the CB2 receptor, SR144528 was recently identified and shown to have a 700-fold higher affinity for the CB2 receptor than for the CB1 receptor (Rinaldi-Carmona et al., 1998).
Because the cannabinoids and LPS both affect the immune and thermoregulatory systems, an investigation was undertaken to determine whether the cannabinoids affect the development of fever after systemic injection by LPS. In this present study, the in vivo effects of two cannabinoid agonists, Δ9-THC (main psychoactive constituent of marijuana) and WIN 55,212-2 (synthetic cannabinoid agonist), were examined for effects on LPS-induced fever. Highly selective CB receptor antagonists SR141716 and SR144528 were used in an attempt to identify the receptor subtype(s) through which WIN 55,212-2 mediates its effects on LPS-induced fever.
Previous SectionNext Section
Materials and Methods
Animals. All animal use procedures were conducted in strict accordance with the National Institute of Health Guide for the Care and Use of Laboratory Animals and were approved by the Institutional Animal Care and Use Committee. Male Sprague-Dawley rats (Zivic-Miller) weighing 250 to 300 g were used in this study. They were housed three per cage for at least 1 week before surgery and were fed laboratory chow and water ad libitum. Ambient temperature was 21 ± 0.3°C, and a 12-h light/dark cycle was used.
Surgery Procedures. Rats were anesthetized with an i.p. injection of a mixture of ketamine hydrochloride (80 mg/kg) and acepromazine maleate (0.2 mg/kg). An incision 2 cm in length was made along the linea alba, and the underlying tissue was dissected and retracted. A transmitter (Mini-Mitter, Sunriver, OR) was then inserted in the i.p. space. After the transmitter was passed through the incision, the abdominal musculature and dermis were sutured independently (Benamar et al., 2002). The animals were returned to individual cages in the environmental room.
Body Temperature Measurement. One week after surgery, the rats were tested in an environmental room (Hotpack), maintained at 21 ± 0.3°C ambient temperature and 52 ± 2% relative humidity. After 1 h of adaptation, two readings at 15-min intervals were averaged to determine the baseline. Either saline or drug was then injected i.p. Tb was measured by a biotelemetry system (Mini-Mitter) using calibrated transmitters implanted i.p. Signals from the transmitter were delivered through a computer-linked receiver. This method minimizes stress to animals during the Tb reading. Thus, the Tb could be monitored continuously and recorded without restraint or any disturbance to the animal. All experiments were started between 9:00 and 10:00 AM to minimize the effect of circadian variation in Tb.
Enzyme-Linked Immunosorbent Assay. The concentration of IL-6 in the plasma was determined by using an enzyme-linked immunosorbent assay kit from R&D Systems (Minneapolis, MN). The assay was performed according to the manufacturer's instructions. At selected time points after i.p. injection of vehicle/LPS or WIN 55,212-2/LPS, rats were killed for collection of blood. Blood samples were immediately centrifuged for measurement of IL-6 in the plasma.
Drugs. The cannabinoid agonist, WIN 55,212-2, and its inactive enantiomer, WIN 55,212-3, were obtained from Sigma-Aldrich (St. Louis, MO). Δ9-THC, SR1411716A, and SR144528 were supplied by the National Institute on Drug Abuse (Rockville, MD). These drugs were dissolved in Cremophor, dimethyl sulfoxide, and saline (1
18). Lipopolysaccharide was the phenol-extracted preparation of Escherichia coli (0111:B4) and was obtained from Sigma-Aldrich and dissolved in pyrogen-free saline.
Statistical Analysis. All results were expressed as mean ± S.E.M. Statistical analysis of differences between groups was determined by analysis of variance followed by Tukey's test. A value of p less than 0.05 was considered statistically significant.
Previous SectionNext Section
Results
The Effect of WIN 55,212-2 on Body Temperature. The i.p. injection of WIN 55,212-2 (0.5—1.5 mg/kg) did not significantly affect the Tb relative to vehicle (Table 1, p > 0.05). However, a higher dose of WIN 55,212-2 (2 mg/kg) produced significant hypothermia compared with control (p < 0.05). Accordingly, we used the nonhypothermic doses of WIN 55,212-2 (0.5—1.5 mg/kg) to allow a clear analysis of the effects of WIN 55,212-2 on LPS-induced fever.
View this table:
In this window
In a new window
TABLE 1
Maximal change (mean ± S.E.M.) in body temperature induced by 0.5 to 2 mg/kg WIN 55,212-2 i.p. ΔTb, variation in body temperature. n, number of rats.
The Effect of WIN 55,212-2 on LPS-Induced Fever. In Fig. 1, LPS injected i.p. (50 μg/kg) induced an increase in Tb that peaked at 180 min (1.25 ± 0.27°C) and again at 5 h (1.52 ± 0.21°C), in agreement with our previous study (Benamar et al., 2000). To determine whether a cannabinoid receptor agonist would interfere with the LPS-induced fever, WIN 55,212-2 (0.5—1.5 mg/kg) was injected 30 min before LPS (Fig. 1). WIN 55,212-2, at a dose of 0.5 mg/kg, did not affect the LPS-induced fever. The LPS-induced fever was partially attenuated by WIN 55,212-2 at a dose of 1 mg/kg (Fig. 1, p < 0.05) and further reduced at a dose of 1.5 mg/kg WIN 55,212-2. Mean Tb before injection was 37.61 ± 0.15°C for the vehicle/LPS group, 37.64 ± 0.19°C for the WIN 55,212-2 (0.5 mg/kg)/LPS group, 37.60 ± 0.17°C for the WIN 55,212-3 (1 mg/kg)/LPS group, 37.87 ± 0.23°C for the WIN 55,212-2 (1.5 mg/kg) group, and 37 ± 14°C for vehicle/saline group.
Fig. 1.
View larger version:
In this page
In a new window
Fig. 1.
Effect of i.p. pretreatment with WIN 55,212-2 (0.5—1.5 mg/kg, -30 min) on LPS-induced fever. LPS was injected at time 0. Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature. *, p < 0.05; **, p < 0.01. Vehicle + LPS versus WIN 55,212-2 + LPS at various concentrations.
Effect of WIN 55,212-3 (Inactive Form) on LPS-Induced Fever. To confirm that WIN55,212-2 functions through the cannabinoid receptor, we tested whether an inactive enantiomer of the aminoalkylindole could affect LPS-induced fever. WIN 55,212-3 (1.5 mg/kg) had no effect on Tb compared with vehicle (Fig. 2, p > 0.05). Moreover, pretreatment with this inactive form did not alter the LPS-induced fever (Fig. 2, p > 0.05). Mean Tb before injection was 37.77 ± 0.11°C for the vehicle/LPS group, 37.67 ± 0.14°C for the WIN 55,212-3/LPS group, 37.65 ± 0.09°C for the WIN 55,212-3/vehicle and group, and 37.62 ± 0.24°C for the vehicle/saline group.
Fig. 2.
View larger version:
In this page
In a new window
Fig. 2.
Effect of i.p. pretreatment with WIN 55,212-3 (1.5 mg/kg, - 30 min) on LPS-induced fever. LPS was injected at time 0. Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature.
Antagonism of WIN 55,212-2 Effect on LPS-Induced Fever by SR141716. To determine the contribution of CB1 receptors in the WIN 55,212-2 effect on LPS-induced fever, SR141716 was administered to rats 30 min before the WIN 55,212-2 and 1 h before LPS (50 μg/kg). SR141716 2.5 (mg/kg i.p.) was found to block the antagonistic effect of WIN 55,212-2 (1.5 mg/kg) on LPS-induced fever (Fig. 3, p < 0.05). Neither the SR141716/vehicle/saline nor vehicle/vehicle/saline group showed an effect on Tb. The mean Tb before injection was 37.44 ± 0.18°C for the vehicle/vehicle/LPS group, 37.59 ± 0.11°C for the SR141716/WIN 55,212-2/LPS group, 37.62 ± 0.06°C for the vehicle/WIN 55,212-2/vehicle, 37.56 ± 0.14°C.
Failure of CB2-Selective Antagonist SR144528 to Reverse the WIN 55,212-2 Effect on LPS-Induced Fever. To determine whether SR14428 antagonizes the effects of WIN 55,212-2 on LPS-induced fever, SR144528 (2.5 mg/kg i.p.) was administered to rats 30 min before treatment with WIN 55,212-2 (1.5 mg/kg i.p.) and 1 h before LPS challenge (Fig. 4). There was no evidence of antagonism by SR144528 of the inhibitory effect of WIN 55,212-2 on LPS-induced fever, even at a high dose of 5 mg/kg (data not shown), nor was there any change in Tb after the administration of SR 144528/vehicle/saline. The mean Tb before injection was 37.76 ± 0.08°C for the vehicle/vehicle/LPS group, 37.71 ± 0.13°C for the SR144528/WIN 55,212-2/LPS group, and 37.63 ± 0.09°C for the SR1445288/vehicle/vehicle.
Fig. 3.
View larger version:
In this page
In a new window
Fig. 3.
Antagonism of WIN 55,212-2 effect on LPS-induced fever by SR141716. Rats were treated i.p. with WIN 55,212-2 (1.5 mg/kg) 30 min before LPS. SR141716 was administered to rats at a dose of 2.5 mg/kg 1 h before LPS (at 0 min). Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature. *, p < 0.05.
Fig. 4.
View larger version:
In this page
In a new window
Fig. 4.
Lack of antagonism by SR144528 on the WIN 55,212-2 effect on LPS-induced fever. SR144528 (2.5 mg/kg i.p.) was administered to the rats 30 min before treatment with WIN 55,212-2 (50 mg/kg) and 1 h before the LPS challenge (at 0 min). Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature.
Effects of SR141716 or SR144528 on LPS-Induced Fever. In separate experiments, we also determined whether CB1 or CB2 receptor antagonists themselves affected the LPS-induced fever. SR141716 or SR144528 was injected 30 min before LPS. SR141716 (2.5 mg/kg) completely abolished the fever produced by LPS (Fig. 5, p < 0.05). In contrast, SR144528 2.5 mg/kg did not alter LPS-evoked fever (Fig. 6, p > 0.05). Neither SR141716 nor SR144528 significantly affected baseline temperatures (Figs. 5, 6, 7), suggesting that the endocannabinoid system does not tonically regulate Tb. Mean Tb before injection was 37.76 ± 0.08°C for the vehicle/LPS group, 37.74 ± 0.15°C for the SR141176A/LPS group, 37.67 ± 0.23°C for the SR141716/vehicle, 37.69 ± 0.15°C for the vehicle/saline group, 37.63 ± 0.13°C for the SR144528/LPS group, 37.66 ± 0.2°C for the SR144528 (2.5 mg/kg) group, 37.59 ± 0.17°C for the SR144528 (1 mg/kg) group, and 37.71 ± 0.21°C for the SR144528 (5 mg/kg) group. The doses of SR141716 and SR144528 were chosen for these studies based on our previous data (Rawls et al., 2002).
Fig. 5.
View larger version:
In this page
In a new window
Fig. 5.
Block of LPS-induced fever by SR141716 (2.5 mg/kg i.p.). LPS was injected at 0 min. SR141716 was injected 30 min before LPS. Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature. * p < 0.05.
Fig. 6.
View larger version:
In this page
In a new window
Fig. 6.
Lack of effect of SR144528 (1, 2.5, and 5 mg/kg i.p.) on LPS-induced fever. LPS was injected at 0 min. SR144528 was injected 30 min before LPS. Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature.
Fig. 7.
View larger version:
In this page
In a new window
Fig. 7.
Lack of effect of SR14428 alone (1, 2.5, and 5 mg/kg) on Tb. Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature.
WIN 55,212-2 Blocks LPS-Induced Increases in IL-6 Levels in Plasma. To test whether inflammatory cytokine levels were effected by this cannabinoid treatment, we determined the levels of plasma IL-6 following cannabinoid addition. LPS induced a significant increase in plasma IL-6 at levels 2 and 4 h postinjection of LPS (Fig. 8). WIN 55,212-2 given 30 min before LPS significantly attenuated the increase in the levels of IL-6 at the 3- and 5-h time points. Neither WIN 55,212-2 by itself nor vehicle affected significantly the levels of IL-6 (data not shown).
Fig. 8.
View larger version:
In this page
In a new window
Fig. 8.
The reduction in plasma levels of IL-6 in rats treated with WIN 55,212-2, 30 min before LPS. Plasma levels were measured 3 and 5 h after LPS challenge. Values shown are the mean ± S.E.M. of six rats per group. Significantly different from the response of rats with vehicle/LPS, *, p < 0.05.
The Effect of Δ9-THC on Body Temperature and on LPS-Induced Fever. To ensure that the ability of cannabinoids to modulate LPS-induced fever was not limited to the aminoalkylindole WIN 55,212-2, we carried out similar experiments using the chemically unique Δ9-THC. The i.p. injection of Δ9-THC at doses of 0.5 or 1 mg/kg did not significantly affect the Tb relative to vehicle (Table 2, p > 0.05). However, a higher dose of Δ9-THC (1.5 mg/kg) produced significant hypothermia compared with control (p < 0.05).
View this table:
In this window
In a new window
TABLE 2
Maximal change (mean ± S.E.M.) in body temperature induced by 0.5 to 1.5 mg/kg Δ9-THC i.p. ΔTb, variation in body temperature. n, number of rats.
The LPS-induced fever showed a trend toward reduction by Δ9-THC at a dose of 0.5 mg/kg (Fig. 9) and significantly reduced at a dose of 1 mg/kg (Fig. 9, p < 0.05). Mean Tb before injection was 37.64 ± 0.12°C for the vehicle/LPS group, 37.71 ± 0.21°C for the Δ9-THC (0.5 mg/kg)/LPS group, and 37.55 ± 0.23°C for the Δ9-THC (1 mg/kg)/LPS group.
Previous SectionNext Section
Discussion
The major finding in the present study is that nonhypothermic doses of WIN 55,212-2 significantly reduced LPS-induced fever. This inhibitory effect is not due to a nonspecific interaction with hydrophobic regions of functional proteins or their lipid surroundings in the cell membrane since WIN 55,212-3, an enantiomer of WIN 55,212-2, did not affect the LPS-induced fever, indicating that the effect of WIN 55,212-2 on LPS-induced fever is stereoselective. To further characterize the participation of cannabinoids on the inhibitory effect on LPS-induced fever, we evaluated another agonist at cannabinoid receptors, Δ9-THC. This agonist at doses of 0.5 or 1 mg/kg also attenuated LPS-induced fever.
Fig. 9.
View larger version:
In this page
In a new window
Fig. 9.
Effect of i.p. pretreatment with Δ9-THC (0.5 or 1 mg/kg) 30 min before LPS-induced fever. LPS was injected at time 0. Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature. *, p < 0.05; **, p < 0.01.
It has been demonstrated that circulating levels of IL-6 rise dramatically following LPS injection with a profile that correlates closely with the development of fever (Harre et al., 2002) and that the neutralization of endogenous IL-6 (Cartmell et al., 2000) or absence of IL-6 in knockout mice (Chai et al., 1996) results in an almost total inhibition of the LPS-induced fever, suggesting that IL-6 is an essential circulating mediator of the brain-derived fever response. In an attempt to investigate the involvement of this inflammatory cytokine in the inhibitory effect of WIN 55,212-2 on LPS-induced fever, we determined the effect of WIN 55,212-2 on plasma levels of IL-6 induced by LPS, examined concurrently at two different time points that coincide with the first (3 h) and second (5 h) peaks of LPS-induced fever. In parallel with the inhibitory effect of WIN 55,212-2 on LPS-induced fever, the plasma level of IL-6 was also attenuated at both time points. Several studies have reported the immunosuppressive effect of cannabinoids on peripheral circulating cytokines, including TNF-α, IL-10, IL-12, IL-6, and IL-1β (Gallily et al., 1997; Smith et al., 2000; Roche et al., 2006). HU210 fully attenuated the LPS-induced increase in the levels of IL-1β, TNF-α, and IL-6, and changes in cytokine levels were accompanied by reduced circulating lymphocyte numbers and increased plasma corticosterone levels in response to acute administration of LPS and/or cannabinoid drugs (Roche et al., 2006). Δ9-THC and WIN 55,212-2 were investigated for their effects on LPS-induced bronchopulmonary inflammation in mice (Berdyshev et al., 1998). Both drugs were found to cause a dose-related decrease in TNF-α in bronchoalveolar lavage fluids. The effect of WIN 55,212-2 on LPS-induced serum cytokine responses has been also investigated in mice. The levels of TNF-α, IL-12, IL-1, and IL-6 were reduced in mice pretreated with WIN 55,212-2 (Smith et al., 2000). The mechanism by which WIN 55,212-2 produces its effect on LPS-induced fever is unknown. The fact that cytokines, such as IL-6, act as endogenous pyrogens and play an important role in the mechanisms responsible for the development of the febrile response during infection and inflammation (Kluger et al., 1995) and that cannabinoids have immunosuppressive effects may provide an explanation for our results. WIN 55,212-2, by diminishing the IL-6 production by LPS, may cause a reduction in LPS-induced fever. Of course, this explanation does not dismiss the possible implication of other mediators of fever, other cytokines (e.g., interleukin-1β), and/or chemokines.
The WIN 55,212-2 effects on LPS-induced fever could occur through the CB1 and/or CB2 receptors. CB1 receptors are located primarily in the central nervous system and are thought to mediate the central effects of cannabinoids (Howlett, 1995). CB1 receptor immunoreactivity has been detected in the hypothalamus (Tsou et al., 1998), including the lateral hypothalamic area and the preoptic anterior hypothalamus, the primary area implicated in body temperature regulation (Moldrich and Wenger, 2000). In contrast, CB2 receptors are expressed mainly in the peripheral immune cells (Dragic et al., 1996). CB2 receptor mRNA has been found in spleen, tonsils, and thymus, which are the major tissues of immune cell production and regulation (Cabral and Pettit, 1998). However, recent evidence shows the expression of CB2 receptor mRNA and protein localization on brainstem neurons and microglia (Cabral and Marciano-Cabral, 2005; Van Sickle et al., 2005). The present study shows that SR141716 prevented the WIN 55,212-2 effects on LPS-induced fever, indicating that a CB1 receptor mechanism mediated the response. The blockade by SR141716 of WIN 55,212-2 effects in the present study is consistent with previous reports. For example, SR141716 blocked cannabinoid agonist-induced hypothermia in rats (Rawls et al., 2002). Several lines of evidence implicate the involvement of cannabinoids, acting via cannabinoid CB1 receptors, in the action of LPS in the rat (Varga et al., 1998). The systemic administration of a selective CB1 receptor antagonist SR141716 protects rats against hypotension induced by bacterial LPS (Varga et al., 1998), and in the initial phase of septic shock induced by LPS, the activation of CB1 receptors by endogenously formed cannabinoids contributes to the inhibition of the neurogenic vasopressor response (Godlewski et al., 2004). CB1 receptors contribute to the immunosuppressive effects of HU210, both centrally and peripherally, since SR141716 attenuated, albeit partially, the decrease in LPS-induced cytokine release induced by this cannabinoid receptor agonist (Roche et al., 2006). Because cytokines are released in response to LPS, and the CB2 receptor has a modulatory role in the immune system, including the cytokine network (Klein et al., 1998), it was tempting to assume that CB2 receptors might contribute to the LPS-induced fever as well. In contrast to SR141716, the present study shows that SR144528 did not affect the inhibitory effects of WIN 55,212-2 on LPS-induced fever, indicating that the thermoregulatory interaction between WIN 55,212-2 and LPS is insensitive to CB2 receptor activation.
An unexpected finding in the present study was the ability of SR141716 itself to attenuate LPS-induced fever. Its effect on LPS-induced fever was similar to that of WIN 55,212-2 and LPS. Interestingly, the LPS-induced cytokines can be modulated by CB agonists through activation of the CB1 receptors in mice (Smith et al., 2000). The decreases in serum TNF-α and IL-12 that occurred in cannabinoid-agonist-treated mice could be blocked by SR141716 but not by SR144528 (Smith et al., 2000). SR141716 itself modulated LPS-induced cytokine responses, and its effects on inflammatory cytokine responses and anti-inflammatory IL-10 were qualitatively similar to those of the CB agonist WIN 55,212-2, suggesting that cytokine modulation by SR141716 seems to be a result of partial agonism (Smith et al., 2000). Several lines of evidence suggest that SR141716, initially characterized as the first potent and selective cannabinoid CB1 receptor antagonist (Rinaldi-Carmona et al., 1994), also has inverse agonist properties. The evidence mainly comes from biochemical studies regarding adenylate cyclase and mitogen-activated protein kinase activity in heterologous expression systems (Bouaboula et al., 1997). The administration of SR141716 alone was sufficient to suppress central and peripheral cytokine responses, in a manner qualitatively and quantitatively similar to the immunosuppressive effects of HU210 (Roche et al., 2006). It is possible that such an effect may occur with SR141716 and LPS-induced fever. In these studies, we also determined whether CB2 receptors are implicated directly in LPS-induced fever. In contrast to SR141716, SR144528 did not influence the development of fever evoked by LPS. In agreement with our previous studies (Rawls et al., 2002), neither SR141716 nor SR144528 by itself altered Tb, suggesting that the endocannabinoid system does not tonically modulate Tb. The present report presents a novel role for cannabinoids by demonstrating a thermoregulatory interaction between cannabinoids and LPS and showing that cannabinoid ligands can prevent the development of fever induced by systemic LPS administration.
Previous SectionNext Section
Footnotes
This work was supported by NIDA Grants DA 06650 and DA 13429.
Article, publication date, and citation information can be found at Journal of Pharmacology and Experimental Therapeutics.
doi:10.1124/jpet.106.113159.
ABBREVIATIONS: Tb, body temperature; LPS, lipopolysaccharide; IL, interleukin; (+)-WIN 55,212-2, (4,5-dihydro-2-methyl-4(4-morpholinyl-methyl)-1-(1-naphthalenyl-carbonyl)-6H-pyrrolo[3,2,1ij]quinolin-6-one; Δ9-THC, Δ9-tetrahydrocannabinol; SR141716, N-(piperdin-1-yl)-5-(4-chloropheny)-1-(2,4-dichloropheny)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride; SR144528, N-[(1S)-endo-1,3,3-trimethylbicyclo[2.2.1]-heptan-2-yl]5-(4-choro-3-methylphenyl)-1-(4-methylbenzyl)pyrazole-3-carboxamide; WIN 55,212-3, S-(-)-[2,3-dihydro-5-methyl-3-[(morpholinyl)-methyl]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthanlenyl)methanone mesylate; CB, cannabinoid.
Received August 30, 2006.
Accepted December 19, 2006.
The American Society for Pharmacology and Experimental Therapeutics
Previous Section
References
↵
Abe M, Oka T, Hori T, and Takahashi S (2001) Prostanoids in the preoptic hypothalamus mediate systemic lipopolysaccharide-induced hyperalgesia in rats. Brain Res 916: 41-49.
CrossRefMedline
↵
Benamar K, Geller EB, and Adler MW (2002) Role of the nitric oxide pathway in kappa-opioid-induced hypothermia in rats. J Pharmacol Exp Ther 303: 375-378.
Abstract/FREE Full Text
↵
Benamar K, McMenamin M, Geller EB, Chung YG, Pintar JE, and Adler MW (2005) Unresponsiveness of mu-opioid receptor knockout mice to lipopolysaccharide-induced fever. Br J Pharmacol 144: 1029-1031.
CrossRefMedline
↵
Benamar K, Xin L, Geller EB, and Adler MW (2000) Blockade of lipopolysaccharide-induced fever by a μ-opioid receptor-selective antagonist in rats. Eur J Pharmacol 401: 161-165.
CrossRefMedline
↵
Berdyshev E, Boichot E, Corbel M, Germain N, and Lagente V (1998) Effects of cannabinoid receptor ligands on LPS-induced pulmonary inflammation in mice. Life Sci 63: PL125-PL129.
CrossRefMedline
↵
Blatteis CM (2006) Endotoxic fever: new concepts of its regulation suggest new approaches to its management. Pharmacol Ther 111: 194-223.
CrossRefMedline
↵
Bouaboula M, Perrachon S, Milligan L, Canat X, Rinaldi-Carmona M, Portier M, Barth F, Calandra B, Pecceu F, Lupker J, et al. (1997) A selective inverse agonist for central cannabinoid receptor inhibits mitogen-activated protein kinase activation stimulated by insulin or insulin-like growth factor: I. Evidence for a new model of receptor/ligand interactions. J Biol Chem 272: 22330-22339.
Abstract/FREE Full Text
↵
Cabral GA and Marciano-Cabral F (2005) Cannabinoid receptors in microglia of the central nervous system: immune functional relevance. J Leukoc Biol 78: 1192-1197.
Abstract/FREE Full Text
↵
Cabral GA and Pettit DA (1998) Drugs and immunity: cannabinoids and their role in decreased resistance to infectious disease. J Neuroimmunol 83: 116-123.
CrossRefMedline
↵
Cartmell T, Poole S, Turnbull AV, Rothwell NJ, and Luheshi GN (2000) Circulating interleukin-6 mediates the febrile response to localised inflammation in rats. J Physiol (Lond) 526: 653-661.
Abstract/FREE Full Text
↵
Chai Z, Gatti S, Toniatti C, Poli V, and Bartfai T (1996) Interleukin (IL)-6 gene expression in the central nervous system is necessary for fever response to lipopolysaccharide or IL-1 beta: a study on IL-1-deficient mice. J Exp Med 183: 311-316.
Abstract/FREE Full Text
↵
Chaperon F and Thiebot MH (1999) Behavioral effects of cannabinoid agents in animals. Crit Rev Neurobiol 13: 243-281.
Medline
↵
Davies JA and Graham JD (1980) The mechanism of action of delta 9-tetrahydrocannabinol on body temperature in mice. Psychopharmacology (Berl) 69: 299-305.
CrossRefMedline
↵
Dogen MD, Patel S, Rudaya AY, Steiner AA, Szekely M, and Romanovsky AA (2004) Lipopolysaccharide fever is initiated via a capsaicin-sensitive mechanism independent of the subtype-1 vanilloid receptor. Br J Pharmacol 143: 1023-1032.
CrossRefMedline
↵
Dragic T, Litwin V, Allaway GP, Martin SR, Huang YX, Nagashima KA, Cayanan C, Maddon PJ, Koup RA, Moore JP, et al. (1996) HIV-1 entry into CD4+ cells is mediated by the chemokine receptor CC-CKR-5. Nature (Lond) 381: 667-673.
CrossRefMedline
↵
Elmquist JK, Scammell TE, and Saper CB (1997) Mechanism of CNS response to systemic immune challenge: the febrile response. Trends Neurosci 20: 565-570.
CrossRefMedline
↵
Fox A, Kesingland A, Gentry C, McNair K, Patel S, Urban L, and James I (2001) The role of central and peripheral cannabinoid 1 receptors in the antihyperalgesic activity of cannabinoids in a model of neuropathic pain. Pain 92: 91-100.
CrossRefMedline
↵
Galieque S, Mary S, Marchand J, Dussossoy D, Carriere D, Carayon P, Bouaboula M, Shire D, LeFur G, and Casellas P (1995) Expression of central and peripheral cannabinoid receptors in human immune tissues and leukocyte subpopulations. Eur J Biochem 232: 54-61.
Medline
↵
Gallily R, Yamin A, Waksmann Y, Ovadia H, Weidenfeld J, Bar-Joseph A, Biegon A, Mechoulam R, and Shohami E (1997) Protection against septic shock and suppression of tumor necrosis factor alpha and nitric oxide production by dexanabinol (HU-211), a nonpsychotropic cannabinoid. J Pharmacol Exp Ther 283: 918-924.
Abstract/FREE Full Text
↵
Godlewski G, Malinowska B, and Schlicker E (2004) Presynaptic cannabinoid CB(1) receptors are involved in the inhibition of the neurogenic vasopressor response during septic shock in pithed rats. Br J Pharmacol 142: 701-708.
CrossRefMedline
↵
Harre EM, Roth J, Pehl U, Kueth M, Gerstberger R, and Hubschle T (2002) Selected contribution: role of IL-6 in LPS-induced nuclear STAT3 translocation in sensory circumventricular organs during fever in rats. J Appl Physiol 92: 2657-2666.
Abstract/FREE Full Text
↵
Hori T, Nakashima T, Take S, Kaizuka Y, Mori T, and Katafuchi T (1991) Immune cytokines and regulation of body temperature, food intake and cellular immunity. Brain Res Bull 27: 309-313.
CrossRefMedline
↵
Howlett AC (1995) Pharmacology of cannabinoid receptors. Rev Pharmacol Toxicol 35: 607-634.
↵
Jansen EM, Haycock DA, Ward SJ, and Seybold VS (1992) Distribution of cannabinoid receptors in rat brain determined with aminoalkylindoles. Brain Res 575: 93-102.
CrossRefMedline
↵
Klein TW, Newton C, and Friedman H (1998) Cannabinoid receptors and immunity. Immunol Today 19: 373-381.
CrossRefMedline
↵
Kluger MJ, Kozak W, Leon LR, Soszynski D, and Conn CA (1995) Cytokines and fever. Neuroimmunomodulation 2: 216-223.
Medline
↵
Lake KD, Compton DR, Varga K, Martin BR, and Kunos G (1997) Cannabinoid-induced hypotension and bradycardia in rats mediated by CB1-like cannabinoid receptors. J Pharmacol Exp Ther 281: 1030-1037.
Abstract/FREE Full Text
↵
Moldrich G and Wenger T (2000) Localization of the CB1 cannabinoid receptor in the rat brain. An immunohistochemical study. Peptides 21: 1735-1742.
CrossRefMedline
↵
Myers RD, Lopez-Valpuesta FJ, Minano FJ, Wooten M, Barwick VS, and Wolpe SD (1994) Fever and feeding in the rat: actions of intrahypothalamic interleukin-6 compared to macrophage inflammatory protein-1β (MIP-1β). J Neurosci Res 39: 31-37.
CrossRefMedline
↵
Ovadia H, Wohlman A, Mechoulam R, and Weidenfeld J (1995) Characterization of the hypothermic effect of the synthetic cannabinoid HU-210 in the rat: relation to the adrenergic system and endogenous pyrogens. Neuropharmacology 34: 175-180.
CrossRefMedline
↵
Rawls SM, Cabassa J, Geller EB, and Adler MW (2002) CB1 receptors in the preoptic anterior hypothalamus regulate WIN 55212-2-induced hypothermia. J Pharmacol Exp Ther 301: 963-968.
Abstract/FREE Full Text
↵
Reche I, Fuentes JA, and Ruiz-Gayo M (1996) Potentiation of Δ9-tetrahydrocannabinol-induced analgesia by morphine in mice: involvement of μ- and κ-opioid receptors. Eur J Pharmacol 318: 11-16.
CrossRefMedline
↵
Rinaldi-Carmona M, Barth F, Heaulme M, Shire D, Calandra B, Cogny C, Martinez S, Maruani J, Neliat G, Caput D, et al. (1994) SR141617A, a potent and selective antagonist of the brain cannabinoid receptor. FEBS Lett 350: 240-244.
CrossRefMedline
↵
Rinaldi-Carmona M, Barth F, Millan J, Derocq JM, Casellas P, Congy C, Oustric D, Sarran M, Bouaboula M, Calandra B, et al. (1998) SR 144528, the first potent and selective antagonist of the CB2 cannabinoid receptor. J Pharmacol Exp Ther 284: 644-650.
Abstract/FREE Full Text
↵
Roche M, Diamond M, Kelly JP, and Finn DP (2006) In vivo modulation of LPS-induced alterations in brain and peripheral cytokines and HPA axis activity by cannabinoids. J Neuroimmunol 181: 57-67
CrossRefMedline
↵
Smith SR, Terminelli C, and Denhardt G (2000) Effects of cannabinoid receptor agonist and antagonist ligands on production of inflammatory cytokines and anti-inflammatory interleukin-10 in endotoxemic mice. J Pharmacol Exp Ther 293: 136-150.
Abstract/FREE Full Text
↵
Tsou K, Brown S, Sanudo-Pena MC, Mackie K, and Walker JM (1998) Immunohistochemical distribution of cannabinoid CB1 receptors in the rat central nervous system. Neuroscience 83: 393-411.
CrossRefMedline
↵
Van Sickle MD, Duncan M, Kingsley PJ, Mouihate A, Urbani P, Mackie K, Stella N, Makriyannis A, Piomelli D, Davison JS, et al. (2005) Identification and functional characterization of brainstem cannabinoid CB2 receptors. Science (Wash DC) 310: 329-332.
Abstract/FREE Full Text
↵
Varga K, Lake K, Martin BR, and Kunos G (1995) Novel antagonist implicates the CB1 cannabinoid receptor in the hypotensive action of anandamide. Eur J Pharmacol 278: 279-283.
CrossRefMedline
↵
Varga K, Wagner JA, Bridgen DT, and Kunos G (1998) Platelet- and macrophage-derived endogenous cannabinoids are involved in endotoxin-induced hypotension. FASEB J 12: 1035-1044.
Source: A Novel Role of Cannabinoids: Implication in the Fever Induced by Bacterial Lipopolysaccharide
Khalid Benamar,
Menachem Yondorf,
Joseph J. Meissler,
Ellen B. Geller,
Ronald J. Tallarida,
Toby K. Eisenstein and
Martin W. Adler
- Author Affiliations
Center for Substance Abuse Research (K.B., M.Y., E.B.G., M.W.A.) and Departments of Microbiology and Immunology (J.J.M., T.K.E.) and Pharmacology (R.J.T.), Temple University School of Medicine, Philadelphia, Pennsylvania
Address correspondence to:
Dr. Khalid Benamar, Center of Substance Abuse Research, Temple University School of Medicine, 3400 North Broad Street, Philadelphia, PA 19140. E-mail: kbenamar@temple.edu
Next Section
Abstract
There is continuing interest in elucidating the actions of drugs of abuse on the immune system and on infection. The present study investigated the effects of the cannabinoid (CB) receptor agonist aminoalkylindole, (+)-WIN 55,212-2 [(4,5-dihydro-2-methyl-4(4-morpholinylmethyl)-1-(1-naphthalenyl-carbonyl)-6H-pyrrolo[3,2,1ij]quinolin-6-one], on fever produced after injection of lipopolysaccharide (LPS), a component of the outer membrane of Gram-negative bacteria, the best known and most frequently used experimental model. Intraperitoneal injection of LPS (50 μg/kg) induced a biphasic fever, with the first peak at 180 min and the second at 300 min postinjection. Pretreatment with a nonhypothermic dose of the cannabinoid receptor agonist WIN 55,212-2 (0.5—1.5 mg/kg i.p.) antagonized the LPS-induced fever. However, pretreatment with the inactive enantiomer WIN 55,212-3 [1.5 mg/kg i.p.; S-(-)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthanlenyl)methanone mesylate] did not. The inhibitory effect of WIN 55,212-2 on LPS-induced fever was reversed by SR141716 [N-(piperdin-1-yl)-5-(4-chloropheny)-1-(2,4-dichloropheny)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride], a selective CB1 receptor antagonist, but not by SR144528 (N-[(1S)-endo-1,3,3-trimethylbicyclo[2.2.1]heptan-2-yl]5-(4-choro-3-methylphenyl)-1-(4-methylbenzyl)pyrazole-3-carboxamide), a selective antagonist at the CB2 receptor. The present results show that cannabinoids interact with systemic bacterial LPS injection and indicate a role of the CB1 receptor subtype in the pathogenesis of LPS fever.
Previous SectionNext Section
Fever is part of the acute-phase reaction to infection, characterized by a raised thermoregulatory set point, which leads to an elevation in body temperature (Tb). The systemic administration of LPS, a powerful activator of the innate immune system and the most commonly used experimental model for systemic infection, induces a variety of sickness-associated responses such as anorexia, increased slow-wave sleep (Hori et al., 1991; Elmquist et al., 1997), change in nociceptive threshold, and fever (Benamar et al., 2000, 2005; Abe et al., 2001). The fever due to LPS and other exogenous pyrogens is believed to be caused by the synthesis and release from monocytes and macrophages of a number of well characterized endogenous pyrogenic factors, including interleukin (IL)-1, IL-6, tumor necrosis factor (TNF)-α, and macrophage inflammatory protein-1 (Myers et al., 1994; Blatteis, 2006). In addition, it has been shown that the opioid system is involved in LPS-induced fever (Benamar et al., 2000, 2005) and that pretreatment with capsaicin, an agonist at the vanilloid receptor, blocks the first phase of LPS-induced fever (Dogen et al., 2004).
Cannabis and its derivative compounds, collectively known as cannabinoids, produce an array of pharmacological symptoms in animals and humans (Ovadia et al., 1995; Chaperon and Thiebot, 1999). Two subtypes of receptors, CB1 and CB2, mediate cannabinoid-induced effects (Howlett, 1995). The development of synthetic cannabinoid agonists has provided remarkable advances in cannabis research. One such ligand is the aminoalkylindole, (+)-WIN 55,212-2 [(4,5-dihydro-2-methyl-4(4-morpholinylmethyl)-1-(1-naphthalenyl-carbonyl)-6H-pyrrolo[3,2,1ij]quinolin-6-one], which displays high selectivity for cannabinoid receptors. Previous studies have demonstrated that WIN 55,212-2 is highly potent and efficacious in vivo and in vitro. WIN 55,212-2 prevents i.v. cocaine self-administration, increases tail-flick reflexes, exerts antihyperalgesic effects, and induces hypothermia in rats, indicating that WIN 55,212-2 is pharmacologically active in vivo (Fox et al., 2001). WIN 55,212-2 undergoes less nonspecific binding than classical cannabinoids and interacts negligibly with other neurotransmitter systems and ion channels (Jansen et al., 1992). In contrast, Δ9-tetrahydrocannabinol (Δ9-THC) has been reported to produce hypothermia by interacting with other neurotransmitters, including serotonin (Davies and Graham, 1980). One of the major advances in CB research has been the development of a potent and selective antagonist of the CB1 receptor, SR141716A. This compound was found to block the hypokinetic, hypothermic, cataleptic, and antinociceptive effects of Δ9-THC and WIN 55,212-2 in mice and rats (Rinaldi-Carmona et al., 1994; Reche et al., 1996). In addition, studies with SR141716 have provided evidence for the presence of CB1 receptors in peripheral tissues as well as in the central nervous system (Varga et al., 1995; Lake et al., 1997).
However, the CB2 receptor subtype has been defined as the peripheral CB receptor, primarily because CB2 mRNA expression has been detected mainly in cells of the immune system (Galieque et al., 1995). The CB2 is expressed inducibly and is present at high levels compared with the CB1 when microglia are in responsive and primed states of activation (Cabral and Marciano-Cabral, 2005). Like the CB1 receptor subtype, the CB2 receptor is a member of the G protein-coupled receptor family and on stimulation causes inhibition of adenylyl cyclase. A potent, selective, and orally active antagonist of the CB2 receptor, SR144528 was recently identified and shown to have a 700-fold higher affinity for the CB2 receptor than for the CB1 receptor (Rinaldi-Carmona et al., 1998).
Because the cannabinoids and LPS both affect the immune and thermoregulatory systems, an investigation was undertaken to determine whether the cannabinoids affect the development of fever after systemic injection by LPS. In this present study, the in vivo effects of two cannabinoid agonists, Δ9-THC (main psychoactive constituent of marijuana) and WIN 55,212-2 (synthetic cannabinoid agonist), were examined for effects on LPS-induced fever. Highly selective CB receptor antagonists SR141716 and SR144528 were used in an attempt to identify the receptor subtype(s) through which WIN 55,212-2 mediates its effects on LPS-induced fever.
Previous SectionNext Section
Materials and Methods
Animals. All animal use procedures were conducted in strict accordance with the National Institute of Health Guide for the Care and Use of Laboratory Animals and were approved by the Institutional Animal Care and Use Committee. Male Sprague-Dawley rats (Zivic-Miller) weighing 250 to 300 g were used in this study. They were housed three per cage for at least 1 week before surgery and were fed laboratory chow and water ad libitum. Ambient temperature was 21 ± 0.3°C, and a 12-h light/dark cycle was used.
Surgery Procedures. Rats were anesthetized with an i.p. injection of a mixture of ketamine hydrochloride (80 mg/kg) and acepromazine maleate (0.2 mg/kg). An incision 2 cm in length was made along the linea alba, and the underlying tissue was dissected and retracted. A transmitter (Mini-Mitter, Sunriver, OR) was then inserted in the i.p. space. After the transmitter was passed through the incision, the abdominal musculature and dermis were sutured independently (Benamar et al., 2002). The animals were returned to individual cages in the environmental room.
Body Temperature Measurement. One week after surgery, the rats were tested in an environmental room (Hotpack), maintained at 21 ± 0.3°C ambient temperature and 52 ± 2% relative humidity. After 1 h of adaptation, two readings at 15-min intervals were averaged to determine the baseline. Either saline or drug was then injected i.p. Tb was measured by a biotelemetry system (Mini-Mitter) using calibrated transmitters implanted i.p. Signals from the transmitter were delivered through a computer-linked receiver. This method minimizes stress to animals during the Tb reading. Thus, the Tb could be monitored continuously and recorded without restraint or any disturbance to the animal. All experiments were started between 9:00 and 10:00 AM to minimize the effect of circadian variation in Tb.
Enzyme-Linked Immunosorbent Assay. The concentration of IL-6 in the plasma was determined by using an enzyme-linked immunosorbent assay kit from R&D Systems (Minneapolis, MN). The assay was performed according to the manufacturer's instructions. At selected time points after i.p. injection of vehicle/LPS or WIN 55,212-2/LPS, rats were killed for collection of blood. Blood samples were immediately centrifuged for measurement of IL-6 in the plasma.
Drugs. The cannabinoid agonist, WIN 55,212-2, and its inactive enantiomer, WIN 55,212-3, were obtained from Sigma-Aldrich (St. Louis, MO). Δ9-THC, SR1411716A, and SR144528 were supplied by the National Institute on Drug Abuse (Rockville, MD). These drugs were dissolved in Cremophor, dimethyl sulfoxide, and saline (1
18). Lipopolysaccharide was the phenol-extracted preparation of Escherichia coli (0111:B4) and was obtained from Sigma-Aldrich and dissolved in pyrogen-free saline.Statistical Analysis. All results were expressed as mean ± S.E.M. Statistical analysis of differences between groups was determined by analysis of variance followed by Tukey's test. A value of p less than 0.05 was considered statistically significant.
Previous SectionNext Section
Results
The Effect of WIN 55,212-2 on Body Temperature. The i.p. injection of WIN 55,212-2 (0.5—1.5 mg/kg) did not significantly affect the Tb relative to vehicle (Table 1, p > 0.05). However, a higher dose of WIN 55,212-2 (2 mg/kg) produced significant hypothermia compared with control (p < 0.05). Accordingly, we used the nonhypothermic doses of WIN 55,212-2 (0.5—1.5 mg/kg) to allow a clear analysis of the effects of WIN 55,212-2 on LPS-induced fever.
View this table:
In this window
In a new window
TABLE 1
Maximal change (mean ± S.E.M.) in body temperature induced by 0.5 to 2 mg/kg WIN 55,212-2 i.p. ΔTb, variation in body temperature. n, number of rats.
The Effect of WIN 55,212-2 on LPS-Induced Fever. In Fig. 1, LPS injected i.p. (50 μg/kg) induced an increase in Tb that peaked at 180 min (1.25 ± 0.27°C) and again at 5 h (1.52 ± 0.21°C), in agreement with our previous study (Benamar et al., 2000). To determine whether a cannabinoid receptor agonist would interfere with the LPS-induced fever, WIN 55,212-2 (0.5—1.5 mg/kg) was injected 30 min before LPS (Fig. 1). WIN 55,212-2, at a dose of 0.5 mg/kg, did not affect the LPS-induced fever. The LPS-induced fever was partially attenuated by WIN 55,212-2 at a dose of 1 mg/kg (Fig. 1, p < 0.05) and further reduced at a dose of 1.5 mg/kg WIN 55,212-2. Mean Tb before injection was 37.61 ± 0.15°C for the vehicle/LPS group, 37.64 ± 0.19°C for the WIN 55,212-2 (0.5 mg/kg)/LPS group, 37.60 ± 0.17°C for the WIN 55,212-3 (1 mg/kg)/LPS group, 37.87 ± 0.23°C for the WIN 55,212-2 (1.5 mg/kg) group, and 37 ± 14°C for vehicle/saline group.
Fig. 1.
View larger version:
In this page
In a new window
Fig. 1.
Effect of i.p. pretreatment with WIN 55,212-2 (0.5—1.5 mg/kg, -30 min) on LPS-induced fever. LPS was injected at time 0. Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature. *, p < 0.05; **, p < 0.01. Vehicle + LPS versus WIN 55,212-2 + LPS at various concentrations.
Effect of WIN 55,212-3 (Inactive Form) on LPS-Induced Fever. To confirm that WIN55,212-2 functions through the cannabinoid receptor, we tested whether an inactive enantiomer of the aminoalkylindole could affect LPS-induced fever. WIN 55,212-3 (1.5 mg/kg) had no effect on Tb compared with vehicle (Fig. 2, p > 0.05). Moreover, pretreatment with this inactive form did not alter the LPS-induced fever (Fig. 2, p > 0.05). Mean Tb before injection was 37.77 ± 0.11°C for the vehicle/LPS group, 37.67 ± 0.14°C for the WIN 55,212-3/LPS group, 37.65 ± 0.09°C for the WIN 55,212-3/vehicle and group, and 37.62 ± 0.24°C for the vehicle/saline group.
Fig. 2.
View larger version:
In this page
In a new window
Fig. 2.
Effect of i.p. pretreatment with WIN 55,212-3 (1.5 mg/kg, - 30 min) on LPS-induced fever. LPS was injected at time 0. Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature.
Antagonism of WIN 55,212-2 Effect on LPS-Induced Fever by SR141716. To determine the contribution of CB1 receptors in the WIN 55,212-2 effect on LPS-induced fever, SR141716 was administered to rats 30 min before the WIN 55,212-2 and 1 h before LPS (50 μg/kg). SR141716 2.5 (mg/kg i.p.) was found to block the antagonistic effect of WIN 55,212-2 (1.5 mg/kg) on LPS-induced fever (Fig. 3, p < 0.05). Neither the SR141716/vehicle/saline nor vehicle/vehicle/saline group showed an effect on Tb. The mean Tb before injection was 37.44 ± 0.18°C for the vehicle/vehicle/LPS group, 37.59 ± 0.11°C for the SR141716/WIN 55,212-2/LPS group, 37.62 ± 0.06°C for the vehicle/WIN 55,212-2/vehicle, 37.56 ± 0.14°C.
Failure of CB2-Selective Antagonist SR144528 to Reverse the WIN 55,212-2 Effect on LPS-Induced Fever. To determine whether SR14428 antagonizes the effects of WIN 55,212-2 on LPS-induced fever, SR144528 (2.5 mg/kg i.p.) was administered to rats 30 min before treatment with WIN 55,212-2 (1.5 mg/kg i.p.) and 1 h before LPS challenge (Fig. 4). There was no evidence of antagonism by SR144528 of the inhibitory effect of WIN 55,212-2 on LPS-induced fever, even at a high dose of 5 mg/kg (data not shown), nor was there any change in Tb after the administration of SR 144528/vehicle/saline. The mean Tb before injection was 37.76 ± 0.08°C for the vehicle/vehicle/LPS group, 37.71 ± 0.13°C for the SR144528/WIN 55,212-2/LPS group, and 37.63 ± 0.09°C for the SR1445288/vehicle/vehicle.
Fig. 3.
View larger version:
In this page
In a new window
Fig. 3.
Antagonism of WIN 55,212-2 effect on LPS-induced fever by SR141716. Rats were treated i.p. with WIN 55,212-2 (1.5 mg/kg) 30 min before LPS. SR141716 was administered to rats at a dose of 2.5 mg/kg 1 h before LPS (at 0 min). Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature. *, p < 0.05.
Fig. 4.
View larger version:
In this page
In a new window
Fig. 4.
Lack of antagonism by SR144528 on the WIN 55,212-2 effect on LPS-induced fever. SR144528 (2.5 mg/kg i.p.) was administered to the rats 30 min before treatment with WIN 55,212-2 (50 mg/kg) and 1 h before the LPS challenge (at 0 min). Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature.
Effects of SR141716 or SR144528 on LPS-Induced Fever. In separate experiments, we also determined whether CB1 or CB2 receptor antagonists themselves affected the LPS-induced fever. SR141716 or SR144528 was injected 30 min before LPS. SR141716 (2.5 mg/kg) completely abolished the fever produced by LPS (Fig. 5, p < 0.05). In contrast, SR144528 2.5 mg/kg did not alter LPS-evoked fever (Fig. 6, p > 0.05). Neither SR141716 nor SR144528 significantly affected baseline temperatures (Figs. 5, 6, 7), suggesting that the endocannabinoid system does not tonically regulate Tb. Mean Tb before injection was 37.76 ± 0.08°C for the vehicle/LPS group, 37.74 ± 0.15°C for the SR141176A/LPS group, 37.67 ± 0.23°C for the SR141716/vehicle, 37.69 ± 0.15°C for the vehicle/saline group, 37.63 ± 0.13°C for the SR144528/LPS group, 37.66 ± 0.2°C for the SR144528 (2.5 mg/kg) group, 37.59 ± 0.17°C for the SR144528 (1 mg/kg) group, and 37.71 ± 0.21°C for the SR144528 (5 mg/kg) group. The doses of SR141716 and SR144528 were chosen for these studies based on our previous data (Rawls et al., 2002).
Fig. 5.
View larger version:
In this page
In a new window
Fig. 5.
Block of LPS-induced fever by SR141716 (2.5 mg/kg i.p.). LPS was injected at 0 min. SR141716 was injected 30 min before LPS. Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature. * p < 0.05.
Fig. 6.
View larger version:
In this page
In a new window
Fig. 6.
Lack of effect of SR144528 (1, 2.5, and 5 mg/kg i.p.) on LPS-induced fever. LPS was injected at 0 min. SR144528 was injected 30 min before LPS. Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature.
Fig. 7.
View larger version:
In this page
In a new window
Fig. 7.
Lack of effect of SR14428 alone (1, 2.5, and 5 mg/kg) on Tb. Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature.
WIN 55,212-2 Blocks LPS-Induced Increases in IL-6 Levels in Plasma. To test whether inflammatory cytokine levels were effected by this cannabinoid treatment, we determined the levels of plasma IL-6 following cannabinoid addition. LPS induced a significant increase in plasma IL-6 at levels 2 and 4 h postinjection of LPS (Fig. 8). WIN 55,212-2 given 30 min before LPS significantly attenuated the increase in the levels of IL-6 at the 3- and 5-h time points. Neither WIN 55,212-2 by itself nor vehicle affected significantly the levels of IL-6 (data not shown).
Fig. 8.
View larger version:
In this page
In a new window
Fig. 8.
The reduction in plasma levels of IL-6 in rats treated with WIN 55,212-2, 30 min before LPS. Plasma levels were measured 3 and 5 h after LPS challenge. Values shown are the mean ± S.E.M. of six rats per group. Significantly different from the response of rats with vehicle/LPS, *, p < 0.05.
The Effect of Δ9-THC on Body Temperature and on LPS-Induced Fever. To ensure that the ability of cannabinoids to modulate LPS-induced fever was not limited to the aminoalkylindole WIN 55,212-2, we carried out similar experiments using the chemically unique Δ9-THC. The i.p. injection of Δ9-THC at doses of 0.5 or 1 mg/kg did not significantly affect the Tb relative to vehicle (Table 2, p > 0.05). However, a higher dose of Δ9-THC (1.5 mg/kg) produced significant hypothermia compared with control (p < 0.05).
View this table:
In this window
In a new window
TABLE 2
Maximal change (mean ± S.E.M.) in body temperature induced by 0.5 to 1.5 mg/kg Δ9-THC i.p. ΔTb, variation in body temperature. n, number of rats.
The LPS-induced fever showed a trend toward reduction by Δ9-THC at a dose of 0.5 mg/kg (Fig. 9) and significantly reduced at a dose of 1 mg/kg (Fig. 9, p < 0.05). Mean Tb before injection was 37.64 ± 0.12°C for the vehicle/LPS group, 37.71 ± 0.21°C for the Δ9-THC (0.5 mg/kg)/LPS group, and 37.55 ± 0.23°C for the Δ9-THC (1 mg/kg)/LPS group.
Previous SectionNext Section
Discussion
The major finding in the present study is that nonhypothermic doses of WIN 55,212-2 significantly reduced LPS-induced fever. This inhibitory effect is not due to a nonspecific interaction with hydrophobic regions of functional proteins or their lipid surroundings in the cell membrane since WIN 55,212-3, an enantiomer of WIN 55,212-2, did not affect the LPS-induced fever, indicating that the effect of WIN 55,212-2 on LPS-induced fever is stereoselective. To further characterize the participation of cannabinoids on the inhibitory effect on LPS-induced fever, we evaluated another agonist at cannabinoid receptors, Δ9-THC. This agonist at doses of 0.5 or 1 mg/kg also attenuated LPS-induced fever.
Fig. 9.
View larger version:
In this page
In a new window
Fig. 9.
Effect of i.p. pretreatment with Δ9-THC (0.5 or 1 mg/kg) 30 min before LPS-induced fever. LPS was injected at time 0. Data are expressed as the mean ± S.E.M. from baseline. N, number of rats. ΔTb, variation in body temperature. *, p < 0.05; **, p < 0.01.
It has been demonstrated that circulating levels of IL-6 rise dramatically following LPS injection with a profile that correlates closely with the development of fever (Harre et al., 2002) and that the neutralization of endogenous IL-6 (Cartmell et al., 2000) or absence of IL-6 in knockout mice (Chai et al., 1996) results in an almost total inhibition of the LPS-induced fever, suggesting that IL-6 is an essential circulating mediator of the brain-derived fever response. In an attempt to investigate the involvement of this inflammatory cytokine in the inhibitory effect of WIN 55,212-2 on LPS-induced fever, we determined the effect of WIN 55,212-2 on plasma levels of IL-6 induced by LPS, examined concurrently at two different time points that coincide with the first (3 h) and second (5 h) peaks of LPS-induced fever. In parallel with the inhibitory effect of WIN 55,212-2 on LPS-induced fever, the plasma level of IL-6 was also attenuated at both time points. Several studies have reported the immunosuppressive effect of cannabinoids on peripheral circulating cytokines, including TNF-α, IL-10, IL-12, IL-6, and IL-1β (Gallily et al., 1997; Smith et al., 2000; Roche et al., 2006). HU210 fully attenuated the LPS-induced increase in the levels of IL-1β, TNF-α, and IL-6, and changes in cytokine levels were accompanied by reduced circulating lymphocyte numbers and increased plasma corticosterone levels in response to acute administration of LPS and/or cannabinoid drugs (Roche et al., 2006). Δ9-THC and WIN 55,212-2 were investigated for their effects on LPS-induced bronchopulmonary inflammation in mice (Berdyshev et al., 1998). Both drugs were found to cause a dose-related decrease in TNF-α in bronchoalveolar lavage fluids. The effect of WIN 55,212-2 on LPS-induced serum cytokine responses has been also investigated in mice. The levels of TNF-α, IL-12, IL-1, and IL-6 were reduced in mice pretreated with WIN 55,212-2 (Smith et al., 2000). The mechanism by which WIN 55,212-2 produces its effect on LPS-induced fever is unknown. The fact that cytokines, such as IL-6, act as endogenous pyrogens and play an important role in the mechanisms responsible for the development of the febrile response during infection and inflammation (Kluger et al., 1995) and that cannabinoids have immunosuppressive effects may provide an explanation for our results. WIN 55,212-2, by diminishing the IL-6 production by LPS, may cause a reduction in LPS-induced fever. Of course, this explanation does not dismiss the possible implication of other mediators of fever, other cytokines (e.g., interleukin-1β), and/or chemokines.
The WIN 55,212-2 effects on LPS-induced fever could occur through the CB1 and/or CB2 receptors. CB1 receptors are located primarily in the central nervous system and are thought to mediate the central effects of cannabinoids (Howlett, 1995). CB1 receptor immunoreactivity has been detected in the hypothalamus (Tsou et al., 1998), including the lateral hypothalamic area and the preoptic anterior hypothalamus, the primary area implicated in body temperature regulation (Moldrich and Wenger, 2000). In contrast, CB2 receptors are expressed mainly in the peripheral immune cells (Dragic et al., 1996). CB2 receptor mRNA has been found in spleen, tonsils, and thymus, which are the major tissues of immune cell production and regulation (Cabral and Pettit, 1998). However, recent evidence shows the expression of CB2 receptor mRNA and protein localization on brainstem neurons and microglia (Cabral and Marciano-Cabral, 2005; Van Sickle et al., 2005). The present study shows that SR141716 prevented the WIN 55,212-2 effects on LPS-induced fever, indicating that a CB1 receptor mechanism mediated the response. The blockade by SR141716 of WIN 55,212-2 effects in the present study is consistent with previous reports. For example, SR141716 blocked cannabinoid agonist-induced hypothermia in rats (Rawls et al., 2002). Several lines of evidence implicate the involvement of cannabinoids, acting via cannabinoid CB1 receptors, in the action of LPS in the rat (Varga et al., 1998). The systemic administration of a selective CB1 receptor antagonist SR141716 protects rats against hypotension induced by bacterial LPS (Varga et al., 1998), and in the initial phase of septic shock induced by LPS, the activation of CB1 receptors by endogenously formed cannabinoids contributes to the inhibition of the neurogenic vasopressor response (Godlewski et al., 2004). CB1 receptors contribute to the immunosuppressive effects of HU210, both centrally and peripherally, since SR141716 attenuated, albeit partially, the decrease in LPS-induced cytokine release induced by this cannabinoid receptor agonist (Roche et al., 2006). Because cytokines are released in response to LPS, and the CB2 receptor has a modulatory role in the immune system, including the cytokine network (Klein et al., 1998), it was tempting to assume that CB2 receptors might contribute to the LPS-induced fever as well. In contrast to SR141716, the present study shows that SR144528 did not affect the inhibitory effects of WIN 55,212-2 on LPS-induced fever, indicating that the thermoregulatory interaction between WIN 55,212-2 and LPS is insensitive to CB2 receptor activation.
An unexpected finding in the present study was the ability of SR141716 itself to attenuate LPS-induced fever. Its effect on LPS-induced fever was similar to that of WIN 55,212-2 and LPS. Interestingly, the LPS-induced cytokines can be modulated by CB agonists through activation of the CB1 receptors in mice (Smith et al., 2000). The decreases in serum TNF-α and IL-12 that occurred in cannabinoid-agonist-treated mice could be blocked by SR141716 but not by SR144528 (Smith et al., 2000). SR141716 itself modulated LPS-induced cytokine responses, and its effects on inflammatory cytokine responses and anti-inflammatory IL-10 were qualitatively similar to those of the CB agonist WIN 55,212-2, suggesting that cytokine modulation by SR141716 seems to be a result of partial agonism (Smith et al., 2000). Several lines of evidence suggest that SR141716, initially characterized as the first potent and selective cannabinoid CB1 receptor antagonist (Rinaldi-Carmona et al., 1994), also has inverse agonist properties. The evidence mainly comes from biochemical studies regarding adenylate cyclase and mitogen-activated protein kinase activity in heterologous expression systems (Bouaboula et al., 1997). The administration of SR141716 alone was sufficient to suppress central and peripheral cytokine responses, in a manner qualitatively and quantitatively similar to the immunosuppressive effects of HU210 (Roche et al., 2006). It is possible that such an effect may occur with SR141716 and LPS-induced fever. In these studies, we also determined whether CB2 receptors are implicated directly in LPS-induced fever. In contrast to SR141716, SR144528 did not influence the development of fever evoked by LPS. In agreement with our previous studies (Rawls et al., 2002), neither SR141716 nor SR144528 by itself altered Tb, suggesting that the endocannabinoid system does not tonically modulate Tb. The present report presents a novel role for cannabinoids by demonstrating a thermoregulatory interaction between cannabinoids and LPS and showing that cannabinoid ligands can prevent the development of fever induced by systemic LPS administration.
Previous SectionNext Section
Footnotes
This work was supported by NIDA Grants DA 06650 and DA 13429.
Article, publication date, and citation information can be found at Journal of Pharmacology and Experimental Therapeutics.
doi:10.1124/jpet.106.113159.
ABBREVIATIONS: Tb, body temperature; LPS, lipopolysaccharide; IL, interleukin; (+)-WIN 55,212-2, (4,5-dihydro-2-methyl-4(4-morpholinyl-methyl)-1-(1-naphthalenyl-carbonyl)-6H-pyrrolo[3,2,1ij]quinolin-6-one; Δ9-THC, Δ9-tetrahydrocannabinol; SR141716, N-(piperdin-1-yl)-5-(4-chloropheny)-1-(2,4-dichloropheny)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride; SR144528, N-[(1S)-endo-1,3,3-trimethylbicyclo[2.2.1]-heptan-2-yl]5-(4-choro-3-methylphenyl)-1-(4-methylbenzyl)pyrazole-3-carboxamide; WIN 55,212-3, S-(-)-[2,3-dihydro-5-methyl-3-[(morpholinyl)-methyl]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthanlenyl)methanone mesylate; CB, cannabinoid.
Received August 30, 2006.
Accepted December 19, 2006.
The American Society for Pharmacology and Experimental Therapeutics
Previous Section
References
↵
Abe M, Oka T, Hori T, and Takahashi S (2001) Prostanoids in the preoptic hypothalamus mediate systemic lipopolysaccharide-induced hyperalgesia in rats. Brain Res 916: 41-49.
CrossRefMedline
↵
Benamar K, Geller EB, and Adler MW (2002) Role of the nitric oxide pathway in kappa-opioid-induced hypothermia in rats. J Pharmacol Exp Ther 303: 375-378.
Abstract/FREE Full Text
↵
Benamar K, McMenamin M, Geller EB, Chung YG, Pintar JE, and Adler MW (2005) Unresponsiveness of mu-opioid receptor knockout mice to lipopolysaccharide-induced fever. Br J Pharmacol 144: 1029-1031.
CrossRefMedline
↵
Benamar K, Xin L, Geller EB, and Adler MW (2000) Blockade of lipopolysaccharide-induced fever by a μ-opioid receptor-selective antagonist in rats. Eur J Pharmacol 401: 161-165.
CrossRefMedline
↵
Berdyshev E, Boichot E, Corbel M, Germain N, and Lagente V (1998) Effects of cannabinoid receptor ligands on LPS-induced pulmonary inflammation in mice. Life Sci 63: PL125-PL129.
CrossRefMedline
↵
Blatteis CM (2006) Endotoxic fever: new concepts of its regulation suggest new approaches to its management. Pharmacol Ther 111: 194-223.
CrossRefMedline
↵
Bouaboula M, Perrachon S, Milligan L, Canat X, Rinaldi-Carmona M, Portier M, Barth F, Calandra B, Pecceu F, Lupker J, et al. (1997) A selective inverse agonist for central cannabinoid receptor inhibits mitogen-activated protein kinase activation stimulated by insulin or insulin-like growth factor: I. Evidence for a new model of receptor/ligand interactions. J Biol Chem 272: 22330-22339.
Abstract/FREE Full Text
↵
Cabral GA and Marciano-Cabral F (2005) Cannabinoid receptors in microglia of the central nervous system: immune functional relevance. J Leukoc Biol 78: 1192-1197.
Abstract/FREE Full Text
↵
Cabral GA and Pettit DA (1998) Drugs and immunity: cannabinoids and their role in decreased resistance to infectious disease. J Neuroimmunol 83: 116-123.
CrossRefMedline
↵
Cartmell T, Poole S, Turnbull AV, Rothwell NJ, and Luheshi GN (2000) Circulating interleukin-6 mediates the febrile response to localised inflammation in rats. J Physiol (Lond) 526: 653-661.
Abstract/FREE Full Text
↵
Chai Z, Gatti S, Toniatti C, Poli V, and Bartfai T (1996) Interleukin (IL)-6 gene expression in the central nervous system is necessary for fever response to lipopolysaccharide or IL-1 beta: a study on IL-1-deficient mice. J Exp Med 183: 311-316.
Abstract/FREE Full Text
↵
Chaperon F and Thiebot MH (1999) Behavioral effects of cannabinoid agents in animals. Crit Rev Neurobiol 13: 243-281.
Medline
↵
Davies JA and Graham JD (1980) The mechanism of action of delta 9-tetrahydrocannabinol on body temperature in mice. Psychopharmacology (Berl) 69: 299-305.
CrossRefMedline
↵
Dogen MD, Patel S, Rudaya AY, Steiner AA, Szekely M, and Romanovsky AA (2004) Lipopolysaccharide fever is initiated via a capsaicin-sensitive mechanism independent of the subtype-1 vanilloid receptor. Br J Pharmacol 143: 1023-1032.
CrossRefMedline
↵
Dragic T, Litwin V, Allaway GP, Martin SR, Huang YX, Nagashima KA, Cayanan C, Maddon PJ, Koup RA, Moore JP, et al. (1996) HIV-1 entry into CD4+ cells is mediated by the chemokine receptor CC-CKR-5. Nature (Lond) 381: 667-673.
CrossRefMedline
↵
Elmquist JK, Scammell TE, and Saper CB (1997) Mechanism of CNS response to systemic immune challenge: the febrile response. Trends Neurosci 20: 565-570.
CrossRefMedline
↵
Fox A, Kesingland A, Gentry C, McNair K, Patel S, Urban L, and James I (2001) The role of central and peripheral cannabinoid 1 receptors in the antihyperalgesic activity of cannabinoids in a model of neuropathic pain. Pain 92: 91-100.
CrossRefMedline
↵
Galieque S, Mary S, Marchand J, Dussossoy D, Carriere D, Carayon P, Bouaboula M, Shire D, LeFur G, and Casellas P (1995) Expression of central and peripheral cannabinoid receptors in human immune tissues and leukocyte subpopulations. Eur J Biochem 232: 54-61.
Medline
↵
Gallily R, Yamin A, Waksmann Y, Ovadia H, Weidenfeld J, Bar-Joseph A, Biegon A, Mechoulam R, and Shohami E (1997) Protection against septic shock and suppression of tumor necrosis factor alpha and nitric oxide production by dexanabinol (HU-211), a nonpsychotropic cannabinoid. J Pharmacol Exp Ther 283: 918-924.
Abstract/FREE Full Text
↵
Godlewski G, Malinowska B, and Schlicker E (2004) Presynaptic cannabinoid CB(1) receptors are involved in the inhibition of the neurogenic vasopressor response during septic shock in pithed rats. Br J Pharmacol 142: 701-708.
CrossRefMedline
↵
Harre EM, Roth J, Pehl U, Kueth M, Gerstberger R, and Hubschle T (2002) Selected contribution: role of IL-6 in LPS-induced nuclear STAT3 translocation in sensory circumventricular organs during fever in rats. J Appl Physiol 92: 2657-2666.
Abstract/FREE Full Text
↵
Hori T, Nakashima T, Take S, Kaizuka Y, Mori T, and Katafuchi T (1991) Immune cytokines and regulation of body temperature, food intake and cellular immunity. Brain Res Bull 27: 309-313.
CrossRefMedline
↵
Howlett AC (1995) Pharmacology of cannabinoid receptors. Rev Pharmacol Toxicol 35: 607-634.
↵
Jansen EM, Haycock DA, Ward SJ, and Seybold VS (1992) Distribution of cannabinoid receptors in rat brain determined with aminoalkylindoles. Brain Res 575: 93-102.
CrossRefMedline
↵
Klein TW, Newton C, and Friedman H (1998) Cannabinoid receptors and immunity. Immunol Today 19: 373-381.
CrossRefMedline
↵
Kluger MJ, Kozak W, Leon LR, Soszynski D, and Conn CA (1995) Cytokines and fever. Neuroimmunomodulation 2: 216-223.
Medline
↵
Lake KD, Compton DR, Varga K, Martin BR, and Kunos G (1997) Cannabinoid-induced hypotension and bradycardia in rats mediated by CB1-like cannabinoid receptors. J Pharmacol Exp Ther 281: 1030-1037.
Abstract/FREE Full Text
↵
Moldrich G and Wenger T (2000) Localization of the CB1 cannabinoid receptor in the rat brain. An immunohistochemical study. Peptides 21: 1735-1742.
CrossRefMedline
↵
Myers RD, Lopez-Valpuesta FJ, Minano FJ, Wooten M, Barwick VS, and Wolpe SD (1994) Fever and feeding in the rat: actions of intrahypothalamic interleukin-6 compared to macrophage inflammatory protein-1β (MIP-1β). J Neurosci Res 39: 31-37.
CrossRefMedline
↵
Ovadia H, Wohlman A, Mechoulam R, and Weidenfeld J (1995) Characterization of the hypothermic effect of the synthetic cannabinoid HU-210 in the rat: relation to the adrenergic system and endogenous pyrogens. Neuropharmacology 34: 175-180.
CrossRefMedline
↵
Rawls SM, Cabassa J, Geller EB, and Adler MW (2002) CB1 receptors in the preoptic anterior hypothalamus regulate WIN 55212-2-induced hypothermia. J Pharmacol Exp Ther 301: 963-968.
Abstract/FREE Full Text
↵
Reche I, Fuentes JA, and Ruiz-Gayo M (1996) Potentiation of Δ9-tetrahydrocannabinol-induced analgesia by morphine in mice: involvement of μ- and κ-opioid receptors. Eur J Pharmacol 318: 11-16.
CrossRefMedline
↵
Rinaldi-Carmona M, Barth F, Heaulme M, Shire D, Calandra B, Cogny C, Martinez S, Maruani J, Neliat G, Caput D, et al. (1994) SR141617A, a potent and selective antagonist of the brain cannabinoid receptor. FEBS Lett 350: 240-244.
CrossRefMedline
↵
Rinaldi-Carmona M, Barth F, Millan J, Derocq JM, Casellas P, Congy C, Oustric D, Sarran M, Bouaboula M, Calandra B, et al. (1998) SR 144528, the first potent and selective antagonist of the CB2 cannabinoid receptor. J Pharmacol Exp Ther 284: 644-650.
Abstract/FREE Full Text
↵
Roche M, Diamond M, Kelly JP, and Finn DP (2006) In vivo modulation of LPS-induced alterations in brain and peripheral cytokines and HPA axis activity by cannabinoids. J Neuroimmunol 181: 57-67
CrossRefMedline
↵
Smith SR, Terminelli C, and Denhardt G (2000) Effects of cannabinoid receptor agonist and antagonist ligands on production of inflammatory cytokines and anti-inflammatory interleukin-10 in endotoxemic mice. J Pharmacol Exp Ther 293: 136-150.
Abstract/FREE Full Text
↵
Tsou K, Brown S, Sanudo-Pena MC, Mackie K, and Walker JM (1998) Immunohistochemical distribution of cannabinoid CB1 receptors in the rat central nervous system. Neuroscience 83: 393-411.
CrossRefMedline
↵
Van Sickle MD, Duncan M, Kingsley PJ, Mouihate A, Urbani P, Mackie K, Stella N, Makriyannis A, Piomelli D, Davison JS, et al. (2005) Identification and functional characterization of brainstem cannabinoid CB2 receptors. Science (Wash DC) 310: 329-332.
Abstract/FREE Full Text
↵
Varga K, Lake K, Martin BR, and Kunos G (1995) Novel antagonist implicates the CB1 cannabinoid receptor in the hypotensive action of anandamide. Eur J Pharmacol 278: 279-283.
CrossRefMedline
↵
Varga K, Wagner JA, Bridgen DT, and Kunos G (1998) Platelet- and macrophage-derived endogenous cannabinoids are involved in endotoxin-induced hypotension. FASEB J 12: 1035-1044.
Source: A Novel Role of Cannabinoids: Implication in the Fever Induced by Bacterial Lipopolysaccharide
