Cardiovascular responses to electrical stimulation of the bed nucleus of the stria terminalis.

To determine whether the influence of the bed nucleus of the stria terminalis (BST) on cardiovascular function can be localized to specific cytoarchitectural areas within the BST, urethane (1.3 g/kg)-anesthetized male Sprague-Dawley rats were probed for cardiovascular reactive sites. Electrical stimuli (50 microA, 50 Hz, and a 0.5 ms pulse duration), delivered through stereotaxically placed glass semimicroelectrodes, were localized to the BST. Sham-stimulated animals served as controls. Stimulation sites were correlated with cytoarchitecturally distinct areas within the BST, and changes in mean arterial pressure (MAP) were subjected to statistical analysis. Systematically probing the BST for cardiovascular reactive sites showed a correlation between evoked responses and distinct cytoarchitectural areas. Stimulation of the medial BST produced increases in MAP; stimulation of the lateral aspect of the BST produced decreases in MAP. Both pressor and depressor responses were evoked from the area ventral to the anterior commissure. Pressor responses were elicited from the area immediately ventral to the anterior commissure, and depressor responses followed stimulation of an area more ventral. All subnuclei showed corroborating cardiovascular responses to 20-30 nl microinjection of sodium glutamate. Taken together, these data provide substantial evidence to indicate that the BST, particularly at more rostral areas, consists of a medial pressor area, a lateral depressor area, and a ventral area with both pressor and depressor zones.