Nitric oxide mediates noradrenaline-induced hypothermic responses and opposes prostaglandin E2-induced fever in the rostromedial preoptic area.
Noradrenaline (NA) microinjected into the rostromedial preoptic area (POA) elicits heat loss responses and opposes prostaglandin E(2)-induced fever. Here, I tested the hypothesis that local synthesis and release of nitric oxide (NO) mediates the NA-induced effects. The unilateral microinjection of the NO donor sodium nitroprusside (SNP, 8.4 nmol), but not that of saline solution, into the NA-sensitive site elicited an increase in tail skin temperature and decreases in the whole-body O(2) consumption rate, heart rate, and colonic temperature simultaneously in urethane-chloralose-anesthetized rats. Pretreatment with SNP greatly attenuated the thermogenic, tachycardic, and hyperthermic effects of prostaglandin E(2) (140 fmol) microinjected into the same site. Furthermore, the NA-induced hypothermic responses were largely blocked by a prior microinjection of an NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA, 5 nmol), but not by that of its inactive enantiomer, N(G)-monomethyl-D-arginine (D-NMMA, 5 nmol), at the same site. These results suggest that the hypothermic and antipyretic effects of NA are mediated by NO in the rostromedial POA.
Osaka
T
T
Health Promotion and Exercise Program, National Institute of Health and Nutrition, 1-23-1 Toyama, Shinjuku 162-8636, Japan. osaka@nih.go.jp
D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D001833:Body Temperature Regulation / Q000187:drug effects; D015232:Dinoprostone / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005334:Fever / Q000139:chemically induced / Q000503:physiopathology*; D006339:Heart Rate / Q000187:drug effects; D007035:Hypothermia / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009599:Nitroprusside / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects; D011301:Preoptic Area / Q000187:drug effects / Q000502:physiology* / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D019323:omega-N-Methylarginine / Q000494:pharmacology
D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D009599:Nitroprusside; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D015232:Dinoprostone; D009638:Norepinephrine