Inhibitory effect of GABAergic drugs in cocaine-induced genital reflexes in paradoxical sleep-deprived male rats.
The aim of this study was to seek whether GABAergic drugs were involved in the action of cocaine on spontaneous genital reflexes (penile erection-PE, and ejaculation-EJ) of paradoxical sleep-deprived (PSD) male rats. After a 4-day period of PSD, each group was administered with GABAergic drugs 1 h prior to cocaine and placed in observation cages. The administration of gamma-aminobutyric acid (GABA)-A agonist (muscimol, 2 and 3 mg/kg sc) reduced the number of animals displaying PE, whereas all doses tested of muscimol and bicuculline significantly reduced the frequency of PE. Pretreatment with the lower doses of GABA-B antagonist, phaclofen (1 and 2 mg/kg sc), also significantly reduced the percentage of rats showing PE; however, after the higher dose injection, the proportion of animals with PE was similar to those seen after vehicle pretreatment. Both GABA-B agonist and antagonist significantly reduced the PE frequency for all doses used compared with the vehicle group. There were no significant differences between control and GABA-A drugs in EJ behavior, whereas phaclofen 2 mg/kg pretreatment increased the ejaculatory latency. These data show that GABAergic compounds inhibited PE in male PSD rats suggesting that this inhibition points to a differential role of GABA receptor subtypes.
Andersen
M L
ML
Department of Psychobiology-Universidade Federal de São Paulo, Escola Paulista de Medicina (UNIFESP/EPM), Rua Napoleão de Barros, 925, Vila Clementino 04024-002, São Paulo, SP, Brazil. mandersen@sti.com.br
Tufik
S
S
D000818:Animals; D003042:Cocaine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004542:Ejaculation / Q000187:drug effects / Q000502:physiology; D018682:GABA Agents / Q000494:pharmacology*; D058785:GABA-A Receptor Agonists; D058787:GABA-A Receptor Antagonists; D008297:Male; D009433:Neural Inhibition / Q000187:drug effects*; D010410:Penile Erection / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000502:physiology; D012892:Sleep Deprivation
D018682:GABA Agents; D058785:GABA-A Receptor Agonists; D058787:GABA-A Receptor Antagonists; D011963:Receptors, GABA-A; D003042:Cocaine