OPIOID ANTAGONISTS AND THE SEXUAL SATIATION PHENOMENON

This study evaluates the effects of the UP injection of naloxone (0.3, 3 and 30 mg/kg) and naltrexone (0.2, 2 and 20 mg/kg) on the sexual sa tiation phenomenon. It was found that both antagonists exert a dose-ba sed biphasic effect on the proportion of sexually exhausted rats displ aying copulation. The intermediate doses of both opioid antagonists we re more effective than the low and high doses in increasing the percen tage of animals engaged in copulation. The analysis of the specific se xual behaviour parameters revealed that naloxone produces a slight inh ibitory effect at the lowest dose, evidenced as an increase in the int romission number. The higher doses of this compound facilitated copula tion reflected as a shortening of the ejaculation latency and the inte rintromission interval (III) and an increase in the copulatory rate. N altrexone treatment had only facilitatory effects at the lower doses b y reducing the III. The higher doses of naloxone (3 and 30 mg/kg) and the intermediate dose of naltrexone (2 mg/kg) decreased the spontaneou s ambulatory behaviour of sexually satiated rats without impairing sex ual behaviour execution. Data suggest a participation of the endogenou s opioid systems in the sexual inhibition resulting from sexual exhaus tion.