Effects of central and peripheral administration of a nitric oxide synthase inhibitor on AVP-induced hypothermia in rats / 中国应用生理学杂志

ABSTRACT

<p><b>AIM</b>To explore the role of nitric oxide (NO) in arginine vasopressin (AVP)-induced hypothermia.</p><p><b>METHODS</b>Colonic temperature was measured at 30 min intervals with a digital thermometer. Effects of central and peripheral administration of nitric oxide synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) on AVP-induced hypothermia were observed in rats.</p><p><b>RESULTS</b>(1) Intravenous injection (i.v.) of AVP (4 microg x kg(-1)) and L-NAME (30 mg x kg(-1)) produced a significant drop in body temperature, respectively. Coadministration of L-NAME i.v. with AVP i.v. did not significantly influence the magnitude of AVP-induced hypothermia. (2) Intracerebroventricular (i.c.v.) injection of L-NAME (1 mg x kg(-1)) caused a significant increase in body temperature, but when the treatments with AVP and L-NAME were combined, i.c.v. injection of L-NAME markedly blocked the hypothermic effect of AVP intravenous injection.</p><p><b>CONCLUSION</b>Endogenous NO in the central nervous system plays a major role in AVP-induced hypothermia. In addition, central NO seems to play a tonic thermoregulatory role by reducing normal body temperature because an increase in body temperature was observed after treatment with NOS inhibitor L-NAME.</p>