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 the blockade of dopamine and norepinephrine reuptake by the presynaptic terminal. Paradoxical sleep (PS) deprivation is known to induce several behavioural alterations most of which suggest the occurrence of supersensitivity of D₂ and a subsensitivity of β₁and β₂receptors.The present study sought to examine the effects of PS deprivation on the actions of cocaine 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 Wistar male rats, at the end of a 4-day period of PS deprivation or at the equivalent time-point to control animals. Moreover, 15 mg/kg of cocaine were administered in animals submitted to immobilization, footshock and forced swimming. The data were analysed by the Chi-square test, and revealed that only PS-deprived animals exhibited penile erections and ejaculation behaviours, which were absent in control animals. PS deprivation increases the sexual behaviour of male rats, probably due to its action on dopaminergic systems. However, further studies need to be carried out in order to clarify the mechanisms involved between PS deprivation and cocaine.