Orexin-a regulates body temperature in coordination with control of arousal state

摘要

Orexins, hypothalamic neuropeptieds, are involved in modulation of food intake and arousal state. To examine further physiological roles of orexin in brain function, the effects of centrally administered orexin- A on body temperature was investigated in rats. Assessed by a telemetry-sensor system implanted into the abdominal cavity, infusion of orexin-A into the third cerebroventricle increased body temperature in a dose-responsive manner. Cumulative ambulatory activity was concomitantly increased during 6 h but not 12 h after administration of orexin-A. Expression of uncoupling protein 1 (UCP1) mRNA in brown adipose tissue, as a marker for peripheal thermogenesis which affects body temperature, failed to increase after orexin-A administration. Expression of UCP3 mRNA in skeletal muscle but not UCP 2 in white adipose tissue was upregulated by infusion of orexin-A. The resulting information indicates that orexin neuron regulates body temperature in coordination with control of arousal system independently of peripheral thermogenesis through the BAT UCP1.