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Abstract
BACKGROUND AND PURPOSE:
Both CB(1) and CB(2) cannabinoid receptors have been shown to play a role in bone metabolism. Crucially, previous studies have focussed on the effects of cannabinoid ligands in murine bone cells. This study aimed to investigate the effects of cannabinoids on human bone cells in vitro.
EXPERIMENTAL APPROACH:
Quantitative RT-PCR was used to determine expression of cannabinoid receptors and liquid chromatography-electrospray ionization tandem mass spectrometry was used to determine the presence of endocannabinoids in human bone cells. The effect of cannabinoids on human osteoclast formation, polarization and resorption was determined by assessing the number of cells expressing α(v) β(3) or with F-actin rings, or measurement of resorption area.
KEY RESULTS:
Human osteoclasts express both CB(1) and CB(2) receptors. CB(2) expression was significantly higher in human monocytes compared to differentiated osteoclasts. Furthermore, the differentiation of human osteoclasts from monocytes was associated with a reduction in 2-AG levels and an increase in anandamide (AEA) levels. Treatment of osteoclasts with LPS significantly increased levels of AEA. Nanomolar concentrations of AEA and the synthetic agonists CP 55 940 and JWH015 stimulated human osteoclast polarization and resorption; these effects were attenuated in the presence of CB(1) and/or CB(2) antagonists.
CONCLUSIONS:
AND IMPLICATIONS Low concentrations of cannabinoids activate human osteoclasts in vitro. There is a dynamic regulation of the expression of the CB(2) receptor and the production of the endocannabinoids during the differentiation of human bone cells. These data suggest that small molecules modulating the endocannabinoid system could be important therapeutics in human bone disease. LINKED ARTICLES: This article is part of a themed section on Cannabinoids in Biology and Medicine. To view the other articles in this section visit British Journal of Pharmacology - Volume 165, Issue 8 - Themed Section: Cannabinoids in Biology and Medicine, Part II. Guest Editors: Itai Bab and Steve Alexander - Wiley Online Library. To view Part I of Cannabinoids in Biology and Medicine visit British Journal of Pharmacology - Volume 163, Issue 7 - Cannabinoids in Biology and Medicine, Part I. Guest Editors: Itai Bab and Steve Alexander - Wiley Online Library.
Source: Cannabinoids and bone: endocannabinoids modul... [Br J Pharmacol. 2012] - PubMed - NCBI
BACKGROUND AND PURPOSE:
Both CB(1) and CB(2) cannabinoid receptors have been shown to play a role in bone metabolism. Crucially, previous studies have focussed on the effects of cannabinoid ligands in murine bone cells. This study aimed to investigate the effects of cannabinoids on human bone cells in vitro.
EXPERIMENTAL APPROACH:
Quantitative RT-PCR was used to determine expression of cannabinoid receptors and liquid chromatography-electrospray ionization tandem mass spectrometry was used to determine the presence of endocannabinoids in human bone cells. The effect of cannabinoids on human osteoclast formation, polarization and resorption was determined by assessing the number of cells expressing α(v) β(3) or with F-actin rings, or measurement of resorption area.
KEY RESULTS:
Human osteoclasts express both CB(1) and CB(2) receptors. CB(2) expression was significantly higher in human monocytes compared to differentiated osteoclasts. Furthermore, the differentiation of human osteoclasts from monocytes was associated with a reduction in 2-AG levels and an increase in anandamide (AEA) levels. Treatment of osteoclasts with LPS significantly increased levels of AEA. Nanomolar concentrations of AEA and the synthetic agonists CP 55 940 and JWH015 stimulated human osteoclast polarization and resorption; these effects were attenuated in the presence of CB(1) and/or CB(2) antagonists.
CONCLUSIONS:
AND IMPLICATIONS Low concentrations of cannabinoids activate human osteoclasts in vitro. There is a dynamic regulation of the expression of the CB(2) receptor and the production of the endocannabinoids during the differentiation of human bone cells. These data suggest that small molecules modulating the endocannabinoid system could be important therapeutics in human bone disease. LINKED ARTICLES: This article is part of a themed section on Cannabinoids in Biology and Medicine. To view the other articles in this section visit British Journal of Pharmacology - Volume 165, Issue 8 - Themed Section: Cannabinoids in Biology and Medicine, Part II. Guest Editors: Itai Bab and Steve Alexander - Wiley Online Library. To view Part I of Cannabinoids in Biology and Medicine visit British Journal of Pharmacology - Volume 163, Issue 7 - Cannabinoids in Biology and Medicine, Part I. Guest Editors: Itai Bab and Steve Alexander - Wiley Online Library.
Source: Cannabinoids and bone: endocannabinoids modul... [Br J Pharmacol. 2012] - PubMed - NCBI
