Effects of cannabinoids on function of testis and secondary sex organs in the Fischer rat.

Chronic oral treatment of young adult male Fischer rats with delta 9-tetrahydrocannabinol (THC), 1, 5 and 25 mg kg-1 day-1, or crude marihuana extract (CME), 3, 15 and 75 mg kg-1 day-1, reduced body weight gain by about 50-80% at the high CME or THC dose and was correlated with decreased food intake. When cannabinoid was administered early in the light cycle (9-11 a.m.), cauda epididymis sperm count and seminal vesicle fluid and fructose content were depressed to 50-65% at the high dosages but were not significantly different from those of pair-fed controls. Administration late in the light cycle (4-5 p.m.) depressed epididymal sperm count, seminal vesicle fluid content, and weight of testis, seminal vesicles and epididymis to 40-80% below that seen for pair-fed controls. 24 h after the last treatment, serum testosterone was unchanged in intubated control and low-dose treated rats, compared with untreated controls, but was elevated nearly twofold in medium-dose-treated rats (p less than 0.05). The results indicate that time of cannabinoid administration as well as feeding pattern are critical in studies of the rat reproductive system.