Effects of morphine or naloxone on cocaine-induced genital reflexes in paradoxical sleep-deprived rats

Effects of morphine or naloxone on cocaine-induced genital reflexes in paradoxical sleep-deprived rats

Author Andersen, M. L. Google Scholar
Frussa-Filho, R. Google Scholar
Tufik, S. Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Abstract The involvement of opioidergic neurotransmission in the modulation of genital reflexes induced by paradoxical sleep deprivation (PSD) and cocaine in rats was the aim of the present study. Morphine (0, 1, 5 and 10 mg/kg) and naloxone (0, 0.3, 3 and 30 mg/kg) were administered prior to saline or cocaine to rats that had been deprived of sleep and the incidence of penile erections (PE) and ejaculations (EJ) was measured. PSD alone induced PE in 50% and EJ in 20% of the rats, but these behaviors were not influenced by morphine or naloxone. Cocaine potentiated the incidence of genital reflexes in PSD rats to 90% (PE) and 70% (EJ). Morphine and not naloxone significantly reduced the percentage of rats displaying this response at the highest doses. Morphine also significantly reduced PE and EJ frequencies at 10 mg/kg. Furthermore, this inhibitory effect of morphine on genital reflexes was prevented by the prior injection of naloxone. Although a number of factors are involved in such a complex phenomenon as PE and EJ, our data show that activation of the opioidergic systems by the agonist morphine reduces genital reflexes-induced by cocaine in PSD males while the antagonist, naloxone, did not have any significant effect. the findings suggest that the stimulating effects of cocaine in potentiating genital reflexes in PSD rats can be unidirectionally modified by opioidergic systems. (C) 2004 Elsevier Inc. All rights reserved.
Keywords sleep deprivation
genital reflexes
morphine
naloxone
opioid
cocaine
sexual behavior
rat
Language English
Date 2004-11-01
Published in Pharmacology Biochemistry and Behavior. Oxford: Pergamon-Elsevier B.V., v. 79, n. 3, p. 515-521, 2004.
ISSN 0091-3057 (Sherpa/Romeo, impact factor)
Publisher Elsevier B.V.
Extent 515-521
Origin http://dx.doi.org/10.1016/j.pbb.2004.09.003
Access rights Closed access
Type Article
Web of Science ID WOS:000225871200013
URI http://repositorio.unifesp.br/handle/11600/28010

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