Abstract
The effect of the thyrotropin-releasing hormone (TRH, protirelin), one of the hypothalamic releasing hormones, on body temperature was investigated in the rat. TRH tartrate dissolved in saline, in doses of 1, 5, 10 and 20 mg/kg, was injected intraperitoneally to male Wistar rats weighing 200-250 g. The rectal temperature was measured with the electronic thermister inserted into 5 cm inner from the anus. TRH tartrate caused a temporary rise in body temperature dose-dependently. The degree of the rise in body temperature ranged from 0.5°C to 1.5°C as a mean and the hyperthermia appeared early and lasted for 80 min after the peptide administration. The thyroidectomized rats injected 20 mg/kg of TRH which induced a significant hyperthermia in the sham-operated animals, failed to show a rise in body temperature. The present results suggest that a release of thyroid hormone might participate in the hyperthermic action of TRH.
