Effects of morphine, beta-endorphin and naloxone on catecholamine levels and sexual behavior in the male rat.
Intraperitoneal administration of the opiate antagonist naloxone hydrochloride (30 mg/kg) to sexually experienced male rats caused a significant reduction in mount and intromission latencies, number of mounts preceding ejaculation and ejaculation latencies. Intraperitoneal adminstration of naloxone (30 mg/kg) also stimulated persistant non-copulators to begin mating and to ejaculate within a twenty minute test period. Conversely, intraperitoneal administration of morphine sulphate (6 mg/kg) as well as intraventricular injection of the endogenous opiate beta-endorphin (6 micrograms) produced a complete loss of copulatory behavior in male rats. The deficit in sexual behavior induced by beta-endorphin was correlated with a significant increase in hypothalamic norepinephrine levels. It is suggested that the endogenous opiates may be involved in the mediation of sexual behavior via an interaction with central catecholaminergic systems.
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects; D002395:Catecholamines / Q000378:metabolism*; D004723:Endorphins / Q000494:pharmacology*; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology*; D051381:Rats; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D001615:beta-Endorphin
D002395:Catecholamines; D004723:Endorphins; D009270:Naloxone; D001615:beta-Endorphin; D009020:Morphine