Centrally induced cardiovascular and sympathetic responses to adrenocorticotrophic hormone

To investigate the effects of adrenocorticotrophic hormone on central cardiovascular regulation, an intracerebroventricular injection of the drug was given to male Wistar rats. With doses of 1 microgram and 10 micrograms per rat, blood pressure began to rise within 1 min, attaining a maximum value 5-10 min later. Both heart rate and abdominal sympathetic nerve activity increased simultaneously with the rise in blood pressure. Injection into the fourth ventricle or intravenous administration of the drug elicited no appreciable cardiovascular responses. These results suggest that endogenous adrenocorticotrophic hormone produced locally in the hypothalamus may participate in central cardiovascular regulation by increasing sympathetic outflow.