Abstract
Exogenous aFGF given via the icv route activates the sympathetic outflow innervating interscapular brawn adipose tissue and adrenal medulla. We investigated the effect of exogenous aFGF given via the iv route on body temperature in rats (Wistar strain) under urethane-chloralose anesthesia using thermistor thermometer or in free moving animals using telemetry system. When animals were given aFGF (100 ng/kg) 30 min before the onset of dark period, nocturnal core temperature (Tc) elevated for 9 h after the aFGF challenge. Peak in Tc induced by aFGF was about 1.5 °C (39.6±0.2) higher than that (38.5±0.1) in animals given saline. Records of tail temperature in rats given aFGF showed three phasic thermal responses (two peaks followed by a trough). The aFGF-induced hyperthermia significantly reduced by a resection of the vagal hepatic branch and abolished completely by the combined hepatic vagotomy with bilateral gastric vagotomy. Furthermore, pretreatment with 30 mg/kg methylpredonisone, artificial glucocorticoid, given intraperitoneally significantly attenuated the aFGF-induced hyperthermia. These data suggest 1) that exogenous aFGF given via the iv route induces fever, and 2) that afferent signals from the hepatic and gastric vagus nerves play an important role in the aFGF -induced fever, 3) that aFGF-induced fever might be triggered by glococorticoid-sensitive inflammation processes within gastrointestinal regions. [J Physiol Sci. 2006;56 Suppl:S228]
