Study: Brain-cell chemical mimics marijuana's 'high'
SAN JOSE, Calif. -- Mother Nature created a way to "tune in, turn on" long before pot smokers rolled their first joint, Stanford scientists have found.
Eavesdropping on conversations between brain cells, researchers learned neurons make their own marijuanalike chemicals called cannabinoids, which indirectly alter the way that information is received and filtered.
When the chemicals are released, "neurons have a harder time deciding which are the relevant things to pay attention to," said investigator John R. Huguenard, associate professor of neurology and neurologic sciences at Stanford University School of Medicine.
For a long time, scientists thought that marijuana altered the mind in a messy and random way.
Now they've identified an elegant modus operandi. It adds to a growing body of research that explains the mechanism behind getting "high." Marijuana mimics the cannabinoids made naturally by our brain -- chemicals that influence a smorgasbord of body functions including movement, thought and perception.
The research, published in Thursday's issue of the journal Nature, sheds light on a powerful neurochemical system. Researchers hope that when they understand the job the chemical does in the day-to-day running of our bodies, they can design new therapeutic drugs.
In their lab, Huguenard and colleagues David Prince and Alberto Bacci injected electric current into rat brain cells, then watched the chatter between the brain's two major types of cells.
When overly excited, one type of neuron releases cannabinoids, which create a calming effect, they found. In effect, the brain cell drugs itself.
But this mellowed-out cell falls down on its job, which is to filter the flow of information rushing into a second type of cell.
Without a good filter, the researchers think this second neuron is flooded with sensory information that affects memory, perception, mood and movement.
Something very similar happens with marijuana use, the scientists believe.
In an accident of nature and chemistry, the compounds in pot are shaped similarly and trigger similar effects.
"Marijuana use . . . affects the way we think," Huguenard said. The new research shows that "part of that is due to changes in the way our brain cells receive incoming information, like sensory information or memories or emotion."
Knight Ridder Newspapers
By Lisa M. Krieger
September 19, 2004
Copyright 2004 IndyStar.com. All rights reserved