RESUMO
The aim of the present study was to test the hypothesis that allopregnanolone infused into the lateral septal nuclei will reduce conflict-like behavior in ovariectomized rats. The interaction with systemic administration of several agonists and antagonists of the GABA-A receptor was assessed. Results showed that intralateral septal doses of allopregnanolone (1.0 microg, P<.05; 2.0 microg, P<.05) or systemic injections of allopregnanolone (1.0 mg/kg s.c., P<.05; 2.0 mg/kg s.c., P<.05), diazepam (2.0 mg/kg i.p., P<.05), or muscimol (0.3 mg/kg i.p., P<.05; 0.6 mg/kg i.p., P<.05) reduced conflict-like behavior. Subthreshold doses of intralateral septal infusions of allopregnanolone (0.5 microg/side) synergized with systemic subthreshold doses of GABA-A agonists: allopregnanolone (0.5 mg/kg, P<.05), diazepam (1.5 mg/kg, P<.05), or muscimol (0.1 mg/kg, P<.05). The GABA-A antagonists, flumazenil (0.1 mg/kg i.p.) and bicuculline (2.0 mg/kg i.p.) attenuated the synergism between intralateral septal infusions of allopregnanolone and diazepam or muscimol, respectively. Conversely, neither flumazenil (P<.05) nor bicuculline (P<.05) attenuated the synergism of the combination allopregnanolone (intralateral septum nuclei; 0.5 microg/side) plus systemic injections of allopregnanolone. In conclusion, allopregnanolone reduced conflict-like behavior probably acting at the GABA-A receptors found in the lateral septal nuclei.