The bed nucleus of the stria terminalis modulates exercise-evoked cardiovascular responses in rats

Abstract

Dynamic exercise evokes sustained cardiovascular changes, which are characterized by blood pressure and heart rate (HR) increases. Although it is well accepted that there is a central nervous system (CNS) mediation of cardiovascular adjustments during dynamic exercise, information on the role of specific CNS structures is limited. The bed nucleus of the stria terminalis (BST) is a forebrain structure known to be involved in central cardiovascular control. Based on this, we tested the hypothesis that BST modulates HR and mean arterial pressure (MAP) responses evoked when rats are submitted to dynamic exercise. Male Wistar rats were tested at three levels of exercise (0.4, 0.8 and 1 km h(1)) on a rodent treadmill before and after BST treatment with CoCl2, a non-selective neurotransmission blocker. Bilateral microinjection of CoCl2 (1 nmol in 100 nl artificial cerebrospinal fluid) into the BST reduced the pressor response to exercise at 0.4 km h(1) as well as the tachycardic responses evoked by exercise at 0.4, 0.8 and 1 km h(1). The BST treatment with CoCl2 did not affect baseline MAP or HR, suggesting a lack of tonic BST influence on cardiovascular parameters at rest. Moreover, BST treatment with CoCl2 did not affect motor performance in the open-field test, which indicates that effects of BST inhibition on cardiovascular responses to dynamic exercise are not due to changes in motor activity. The present results suggest that local neurotransmission in the BST modulates exercise-related cardiovascular adjustments. Data indicate that BST facilitates pressor and tachycardic responses evoked by dynamic exercise in rats.