Dopaminergic Modulation of Renin Activity and Aldosterone and Prolactin Secretion in the Spontaneously Hypertensive Rat 1

Abstract

Abstract

The effect of metoclopramide, a dopamine antagonist, and L-dopa on plasma aldosterone (PA), plasma renin activity (PRA), and plasma prolactin (PRL) was studied in eight spontaneously hypertensive rats (SHR) and eight Wistar-Kyoto normotensive rats (WKY). Basal PRL levels were greater (P < 0.005) in the SHR (24.3 ± 1.0 ng/ml) than in the WKY (13.7 ± 0.7 ng/ml). Baseline PA in the SHR (49.9 ± 7.2 ng/dl), although higher, were not statistically different from those in the WKY (38.0 ± 7.0 ng/dl). Basal PRA in the SHR (11.0 ± 0.6 ng/ml hr^-1) was not different from that of WKY (11.4 ± 0.8 ng/ml hr^-1). Although both groups of rats displayed significant PA, PRA, and PRL responses to metoclopramide the responses were greater (P < 0.01) in the SHR. These responses to metoclopramide remained exaggerated even after the rats were pretreated with L-dopa. However, administration of L-dopa resulted in similar suppression of all three hormones in the SHR and in the WKY. These findings suggest that there is altered dopaminergic modulation of secretion of PA, PRA, and PRL in the SHR. Alterations in peripheral and central dopamine control of hormone secretion may play a role in the pathogenesis of essential hypertension in the SHR.