Plasma corticosterone responses to electrical stimulation of the bed nucleus of the stria terminalis

Abstract

The effect of ventral septal stimulation on pituitary-adrenal function was assessed by evaluating plasma corticosterone obtained prior to and following sham or electrical stimulation of the bed nucleus of the stria terminalis (BNST) of female rats anesthetized with urethane (1.3 g·kg −1). Hippocampal EEG, ECG, heart rate, blood pressure and respiration were routinely monitored; timed blood samples (0.2 ml) for determining plasma corticosterone (RIA) were obtained from a catheterized tail artery. Samples were taken at 0.5 min prior to and at 5, 10, 15 and 30 min after initiation of stimulation. Whereas increased plasma corticosterone levels followed stimulation of the medial aspect of the BNST, lateral stimulation resulted in decreased plasma corticosterone levels. The overall increase in plasma corticosterone following medial stimulation was 24%; the overall decrease was 13%. The largest increase in plasma corticosterone (36%) occurred at 30 poststimulation; the largest decrease (22%) occurred at 15 min. Stimulation of the most rostral aspect of the BNST produced plasma corticosterone responses similar to that observed following medial stimulation. In contrast, no changes in corticosterone levels were observed following either sham stimulation of the corpus callosum, fornix or anterior commissure.