Effect of tetrahydrocannabinols on pubertal body weight spurt and sex hormones in developing male rats.

Chronic administration of delta 8- and delta 9-tetrahydrocannabinols (4 mg/kg b.wt. i.p.) to sexually developing male rats every alternate day from age day 16 to age day 87 resulted in a significant decrease in pubertal growth spurts, especially the second peak. Endogenous testosterone, dihydrotestosterone, LH and FSH concentration in blood declined significantly from those of the control animals. When the drugs were withdrawn at mid-puberty (age day 40) the "catch-up" phenomenon in body growth weas evident although testosterone level continued to be suppressed but dihydrotestosterone level recovered. Withdrawal of the drugs resulted in better recovery in LH level compared to that of FSH. Administration of LH-RH to the animals receiving drugs until day 87 resulted in significantly (P less than 0.001) lower levels of gonadotropins than those in the control animals. The inhibition in delta 9-THC-treated animals was more severe than in delta 8-THC-treated ones. When the drug was withdrawn, delta 8-THC-treated animals responded to LH-RH stimulation better than did those treated with delta 9-THC. These findings suggest that the tetrahydrocannabinols perhaps mainly affect pituitary function.