Natural Chemical May Tamp Down the Effects of an Intoxicant Found in Marijuana

A team of French scientists discovered a natural chemical brake that can tamp down the effects of tetrahydrocannabinol (THC), the main intoxicant found in marijuana.

The researchers believe this could lead to effective ways of protecting against memory loss, torpor and other side effects of being stoned. "We have this built in negative feedback mechanism, a brake on cannabis intoxication," said Dr. Pier Vincenzo Piazza, principal author of the study published in the journal Science. Dr. Piazza and his team investigated the role of neurosteroids in addiction which are a class of hormones produced in the brain and that have been implicated in regulating mood and cognitive activities.

After testing rats and mice by making them high on the active ingredients of cocaine, morphine, nicotine, alcohol and marijuana, the researchers measured the increase in pregnenolone, a precursor to all steroid hormones that was thought to be otherwise inactive. THC sent prenenolone levels soaring by 1,500 percent - an increase that was about 50 times greater than that produced by the active ingredients of other drugs.

"This was a surprising finding," said Piazza. "We thought this must have a direct role. We didn't know it would be a brake, but that there had to be something." THC works through a cell membrane receptor, known as the Type One cannabinoid receptor. While in the brain, these receptors allow THC to enter the axon terminals of neurons. The researchers stimulated or inhibited these receptors in the rodents employed in their study. "There was no identified effect for this substance before. Everyone thought it was only useful to build other steroid hormones," Piazza explained.