The bed nucleus of the stria terminalis (BST) is known to contain estrogen (E)- concentrating neurons. In addition, injections of E into BST have been reported to potentiate the sympathoinhibitory arterial pressure (AP) and heart rate (HR) responses elicited by glutamate (Glu) stimulation. In this study, the effect of GABA-A antagonist receptors, bicuculline methiodide (BMI), in the rostral ventrolateral medulla (RVLM) on the cardiovascular responses to Glu stimulation of BST (0.25 M; 20 nl) was investigated in the chloralose anaesthetized, ovariectomized (OVX; n=6) or OVX+E treated (30 pg/ml plasma E, n=7) female Wistar rats. Glu stimulation of the BST elicited decreases in AP (-28.1±3.7 mmHg) and HR (-14.2 ± 3.5 bpm) in the OVX+E animals and in OVX only animals (AP, -22.48 ± 2.68 mmHg; HR, -12.2 ± 2.1 bpm). Microinjection of GABA-A receptor antagonist, BMI (1.0mM, 100nl) into the ipsilateral RVLM reversibly attenuates glutamate induced bradycardia and depressor responses to BST stimulation in both group of animals (OVX; n=6 AP,-8.03±3.15 and HR,-5.8±4.2) but in OVX+E animals only attenuates glutamate induced bradycardia but not depressor response (OVX+E; n=7 AP,-16.0±2.4 and HR, -5.84±2.0). These data suggest RVLM sympathetic premotor neurons contain GABA receptors, which mediate the sympathoinhibitory responses to stimulation of BST in OVX animals.