Marijuana has never been linked to an overdose death, and new findings may explain why.

Published in the journal Science, French researchers have identified a natural hormone that reverses marijuana intoxication in rats.

In an interview with WebMD, study author Dr. Pier Vincenzo Piazza explained that rats exposed to THC showed a dramatic rise in a brain hormone called pregnenolone. The hormone also seemed to prevent marijuana's intoxicating effects.

"When the brain is stimulated by high doses of THC, it produces pregnenolone – a 3,000 percent increase – that inhibits the effects of THC."

But the study, originally meant for developing a treatment for cannabis addiction, has been met with different interpretations.

While the authors say that an addiction treatment based on pregnenolone could soon be tested in humans, others believe the study explains how the brain protects itself from a marijuana overdose.

By binding to cannabinoid receptors, THC triggers the release of pregnenolone, which in turn weakens THC's action on the receptors – a negative feedback loop that could prevent marijuana users from getting too high.

Considering the low rates of cannabis addiction, Mitch Earleywine, a professor of psychology at the University at Albany, SUNY, adds that a drug for cannabis abuse may not even be necessary.

"Although the authors pitch this as a novel way to treat cannabis abuse, it's actually a superb – if partial – explanation for why cannabis appears to have no potential lethal dose and why its capacity for creating addiction is more like caffeine's than that of any illicit drug."

Scientists have been studying pregnenolone since the 1940s for conditions like stress and arthritis, but only recently has the hormone caught the attention of cannabis researchers.

While pregnenolone pills are sold as supplements, Dr. Piazza and his team are now working on how to deliver the hormone in higher doses.

Source: WebMD via LeafScience