The effect of apomorphine on genital reflexes in male rats deprived of paradoxical sleep.
Drugs that stimulate dopamine (DA) systems can stimulate sexual arousal in male rats and humans, and previous work has shown that cocaine enhances genital reflexes [penile erection (PE) and ejaculation (EJ)] in rats deprived of paradoxical sleep (PS). The present study sought to expand the latter finding by assessing the effects of DA receptor agonist apomorphine in sleep-deprived rats. Apomorphine in doses ranging from 10 to 240 microg/kg was administered intraperitoneally to rats that had been deprived of sleep for 4 days and to normal controls, and the incidence of PEs and EJs was measured for 60 min. Sleep deprivation alone induced PE and this effect was potentiated by apomorphine, with maximal effects occurring with the 120 microg/kg dose; results for this dose group differed from those of PSD groups treated with 0, 10, 20, 40, 80, and 240 microg/kg of apomorphine. Sleep deprivation alone also induced spontaneous EJ, but this response was not potentiated by apomorphine in the dose range tested. We suggest that the potentiating effects of apomorphine on PE are likely due to PSD-induced DA receptor supersensitivity.
Andersen
Monica L
ML
Department of Psychobiology, Universidade Federal de São Paulo, Escola Paulista de Medicina (UNIFESP/EPM), Rua Napoleão de Barros, 925 Vila Clementino, São Paulo SP-04024-002, Brazil. mandersen@sti.com.br
Bignotto
Magda
M
Tufik
Sergio
S
D000704:Analysis of Variance; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D018491:Dopamine Agonists / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004542:Ejaculation / Q000187:drug effects*; D008297:Male; D010410:Penile Erection / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D012892:Sleep Deprivation / Q000503:physiopathology*
D018491:Dopamine Agonists; D001058:Apomorphine