The effects of marijuana extract and delta 9-tetrahydrocannabinol on luteal function in the rhesus monkey.

The effects of marijuana extract (ME) and delta 9-tetrahydrocannabinol (THC) on corpus luteum function were studied in the rhesus monkey by the use of in vivo and in vitro techniques. THC (2.5 mg/kg) or vehicle (3% Tween 80 in saline) was administered by an intramuscular injection to rhesus monkeys on day 20, 21, or 22 of the menstrual cycle. Progesterone (P) levels were measured at 6-hour intervals for the first 24 hours after treatment. THC caused a significant decrease in P levels during this 24-hour period. This decrease was reversed by the administration of human chorionic gonadotropin (hCG) at 6 hours after THC administration. When THC was administered 2 hours after hCG, it failed to inhibit the expected rise in serum P levels caused by hCG. Direct effects of the drugs on P production were studied with the use of dispersed luteal cells obtained from monkeys on day 21 or 22 of the menstrual cycle. Neither ME nor THC had any effect on basal P production in these in vitro studies. These data suggest that the inhibitory effect of THC on P levels during the luteal phase are not mediated by a direct effect of the drug on ovarian steroid production.