Neuromedin U (NMU) is a brain-gut peptide, which peripherally stimulates smooth 
muscle, increases of blood pressure, alters ion transport in the gut, controls 
local blood flow, and regulates adrenocortical function. Although 
intracerebroventricular (i.c.v.) administration of NMU is known to decrease food 
intake and body weight, little is known about its effect on other physiological 
functions. We examined the effects of i.c.v. administration of NMU on mean 
arterial pressure (MAP), heart rate (HR), and plasma norepinephrine in conscious 
rats. Neuromedin U (0.05 and 0.5 nmol) provoked an increase in MAP (93.8 +/- 0.5 
to 123.5 +/- 1.7 and 94.7 +/- 0.8 to 132.7 +/- 3.0 mm Hg, respectively) and HR 
(334.9 +/- 6.0 to 494.1 +/- 6.9 and 346.3 +/- 3.3 to 475.1 +/- 8.9 beats/min, 
respectively). In contrast, plasma norepinephrine increased only with a high 
dose of neuromedin U. Intravenously administered NMU (0.5 nmol) elicited a small 
and short lasting increase in MAP, compared to that by i.c.v. NMU. These results 
indicate that central neuromedin U regulates sympathetic nervous system activity 
and affects cardiovascular function.