Interactions of cocaine and delta 9-tetrahydrocannabinol with the hypothalamic-hypophysial axis of the female rat.

The acute effects of cocaine and/or delta 9-tetrahydrocannabinol (THC) were studied in ovariectomized female rats. Intermediate doses of cocaine (10 or 20 mg/kg) caused an increase in serum luteinizing hormone (LH) and a decrease in serum prolactin levels, whereas a higher dose (40 mg/kg) caused a decrease in serum LH. THC (10 mg/kg) attenuated serum LH and prolactin levels. The THC effect on LH was blocked by cocaine. Neither drug alone or in combination affected serum follicle-stimulating hormone levels. The cocaine-induced changes in LH levels were closely paralleled by changes in hypothalamic norepinephrine content, suggesting a neurochemical basis for cocaine's action on LH release.