The effects of acute cocaine administration in paradoxical sleep-deprived rats

Recent studies demonstrate the action of cocaine on reward pathways, which are activated by pleasant stimuli. Cocaine's mechanism of action involves t he blockade of dopamine and norepinephrine reuptake by the presynaptic term inal. Paradoxical sleep (PS) deprivation is known to induce several behavio ural alterations most of which suggest the occurrence of supersensitivity o f D-2 and a subsensitivity of beta(1) and beta(2) receptors. The present st udy sought to examine the effects of PS deprivation on the actions of cocai ne on the erection and ejaculation behaviours in rats. Four different doses of cocaine (3.5, 7.0, 15.0 and 30.0 mg/kg) were acutely administered to Wi star male rats, at the end of a 4-day period of PS deprivation or at the eq uivalent time-point to control animals. Moreover, 15 mg/kg of cocaine were administered in animals submitted to immobilization, footshock and forced s wimming. The data were analysed by the Chi-square test, and revealed that o nly PS-deprived animals exhibited penile erections and ejaculation behaviou rs, which were absent in control animals. PS deprivation increases the sexu al behaviour of male rats, probably due to its action on dopaminergic syste ms. However, fur ther studies need to be carried out in order to clarify th e mechanisms involved between PS deprivation and cocaine.