Action of naltrexone on the sexual impairment of obese cafeteria rats.

Two experiments were performed to explore 1) the sexual behavior of male obese cafeteria rats, 2) a possible role of endogenous opiates in the regulation of their sexual behavior. In obese cafeteria rats the proportion of ejaculators and the number of ejaculations per hour were significantly lower compared to controls. Naltrexone provoked an increase in the number of ejaculations/h both in control and cafeteria rats due to an induction of copulatory behavior in sexually inactive rats. Thus nutritional obesity provokes an impairment of sexual behavior and an injection of naltrexone (2.5 mg/Kg IP) lifts this inhibition in a similar way as in inactive, control rats.