Tolerance to the Reproductive Effects of Δ9-Tetrahydrocannabinol

Abstract

The reproductive effects of marihuana and Δ9-tetrahydrocannabinol (THC) have received much attention from the scientific community for the past several years. Early clinical reports indicated that chronic marihuana use may be associated with decreased hormone levels and infertility. Later studies failed to confirm these findings. Studies in laboratory animals clearly demonstrate that THC has pronounced effects on reproductive hormones and on ovulation and spermatogenesis, and have provided much information on how these effects are produced. These studies have not, however, provided much insight into the apparent discrepancy in the pronounced drug effects reported in laboratory animal studies and the less impressive effects of absence of disruptive effects reported in clinical studies. Since much of our knowledge of human reproductive physiology has been obtained from studies in laboratory animals, it is difficult to ascribe these differences to species variations. It is more likely that the discrepancies in laboratory animal studies and the clinical studies are based on differences in experimental designs and failure to consider the role of the development of drug tolerance in the conclusions of these studies.