GABAergic drugs and socio-sexual behavior

To elucidate the role of GABA in the control of sexual behavior, the effects of the GABA(A) agonist 4,5,6,7-tetrahydroisoxazolo[5,4c]-pyridin-3-ol (THIP), the GABA transaminase inhibitors sodium valproate and gamma-acetylen-GABA (GAG), and the GABA synthesis inhibitors isoniazide and deoxypyridoxine were evaluated in sexual behavior, exploration, and sociosexual interactions with a receptive female or a castrated male. Furthermore, to discriminate possible general inhibitory effects from those specific to sexual behavior, the doses of the drugs that produced a significant inhibition of copulation were tested in a free drinking procedure. THIP (16 mg/kg), sodium valproate (400 mg/kg), GAG (100 mg/kg), and deoxypyridoxine (400 mg/kg) produced a strong inhibition of sexual behavior. The percentage of animals displaying mounts and intromissions as well as the mean number of mounts and intromissions were significantly reduced. Sociosexual interactions with a receptive female or a castrated male and exploratory behaviors were also reduced. The most consistent effects observed were reductions in sniffing, self-grooming, and rearing. Drinking behavior was significantly reduced in doses that inhibited sexual behavior. These results further support the hypothesis that altered GABAergic neurotransmission produces reduced sensitivity to environmental stimuli and thereby inhibits sexual and drinking behavior in a nonspecific way.