Its called Pregnenolone, and a new study suggests it may be released as a natural response to counteract the mental effects of marijuana. Researchers discovered the effect by administering massive doses of marijuana to lab rats. Monitoring the rats brains, they discovered elevated quantities of Pregnenolone being metabolized in response to the marijuana, which in turn reduced many of the mental effects of the drug. Its not the first time researchers have isolated the intoxicating effects of marijuana or found ways to counteract them, but this study has drawn particular interest because of its mechanism.