Acute effects of natural and synthetic cannabis compounds on prolactin levels in human males.

Plasma prolactin levels were determined in 23 adult males prior to and following administration of delta 9-tetrahydrocannabinol (THC) (17.5 mg orally), a synthetic cannabis compound, Nabilone (2 mg orally), a 1-g marihuana cigarette containing 1.83% THC, smoked under controlled conditions and placebo capsules and cigarettes for each of the active cannabis compounds. In order to control for possible influence of previous cannabis use history on prolactin response, three groups of subjects were studied--regular (daily) marihuana users, intermittent (weekly) marihuana users, and occasional (monthly) marihuana users. Each subject served as his own control for each drug condition. Double blind studies were conducted on a residential research ward. All baseline prolactin values were within the normal range for healthy adult males. There were no statistically significant differences in plasma prolactin levels among the three subject groups prior to administration of THC, Nabilone, marihuana or their respective placebos. There were no statistically significant changes in prolactin levels following TCH, Nabilone or marihuana smoking. Only placebo administration to regular and occasional marihuana users was followed by a significant increase in plasma prolactin levels. These findings indicate that acute administration of cannabis compounds, either orally or via smoking, does not significantly affect plasma prolactin levels in adult human males.