Cardiovascular effects of intrahypothalamic injections of alpha-melanocyte stimulating hormone.
Injection of alpha-melanocyte stimulating hormone (alpha-MSH, 0.6-1.2 nmol in 100-300 nl) into the rostral dorsomedial hypothalamic nucleus of the halothane anesthetized rat resulted in a 12% increase in heart rate (41 +/- 4 bpm) which was accompanied by a slight increase in blood pressure (5 +/- 1 mm Hg). The response was characterized by a gradual onset, with a peak increase at 7 +/- 1 min and a duration of 51 +/- 6 min. Tachyphylaxis to the response was apparent for at least 180 min following initial exposure to the peptide. In contrast to the increase in heart rate observed following alpha-MSH injection into the dorsomedial nucleus, injections into the medial preoptic, anterior, paraventricular or posterior hypothalamic nuclei had no significant effects on blood pressure and heart rate. These data suggest a possible role for brain alpha-MSH in the central control of heart rate at a site within the dorsomedial nucleus of the hypothalamus.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001931:Brain Mapping; D004302:Dorsomedial Hypothalamic Nucleus / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects*; D007031:Hypothalamus / Q000187:drug effects*; D007032:Hypothalamus, Anterior / Q000187:drug effects; D007034:Hypothalamus, Posterior / Q000187:drug effects; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000494:pharmacology*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects; D011301:Preoptic Area / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains
D009074:Melanocyte-Stimulating Hormones