Food restriction or sleep deprivation: which exerts a greater influence on the sexual behaviour of male rats?

The purpose of this study was to determine the effects of food restriction (FR) and paradoxical sleep deprivation (PSD), either alone or in combination, on sexual behaviours (mount, intromission and ejaculation) in adult male rats. Diet restriction began at weaning with 6g/day of food, and the amount of food was increased by 1g/week until it reached 15g/day amount (in adulthood). During adulthood, rats under FR and those fed ad libitum were either subjected to PSD for 96h or maintained in home-cage groups. The results indicated that both FR and ad libitum sleep-deprived groups showed a significant decrease in performance and motivation to initiate sexual behaviour, reflected by the increase in mount and intromission latencies and decreased copulatory rate. FR associated with PSD reversed the adverse effects of sleep deprivation on the number of ejaculations and inter-copulatory interval. Testosterone concentrations decreased after sleep deprivation, regardless of food availability; while progesterone was significantly higher in the FR-PSD group only. In light of the limited understanding of the link between secretion patterns and neural-hormonal control of food availability related to sexual behaviour, our data indicate that sleep loss affects sexual responses, and FR was able to restore some of the sexual parameters investigated.