Regulation of body temperature by thyrotropin-releasing hormone in neonatal chicks.
To understand thermal regulation of neonatal chicks, the contribution of thyrotropin-releasing hormone (TRH), a key regulator of the hypothalamus-pituitary-thyroid axis, was investigated. Intracerebroventricular (i.c.v.) injection of TRH (5 and 20 microg) increased body temperature, but did not change plasma T3 and T4 concentrations. Intraperitoneal (i.p.) injection of triiodothyronine (T3) and thyroxine (T4) did not influence body temperature. Thereafter, the relationships between TRH and the hypothalamus-pituitary-adrenal axis and sympathetic nervous system were further investigated. Central TRH stimulated both corticosterone and epinephrine release. The i.c.v. injection of a corticotropin-releasing factor receptor antagonist attenuated the change in body temperature and corticosterone concentration caused by TRH, but did not influence plasma T3 and T4 concentrations. The i.p. injection of epinephrine did not induce hyperthermia. Therefore, the thermoregulatory response to TRH may differ in neonatal stages being dependent upon the stimulation of the hypothalamus-pituitary-adrenal axis rather than the hypothalamus-pituitary-thyroid axis.
Takahashi
Hirokazu
H
Laboratory of Advanced Animal and Marine Bioresources, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka 812-8581, Japan.
Iigo
Masayuki
M
Ando
Kôichi
K
Tachibana
Tetsuya
T
Denbow
D Michael
DM
Furuse
Mitsuhiro
M
D000818:Animals; D000831:Animals, Newborn / Q000097:blood / Q000502:physiology; D001831:Body Temperature / Q000187:drug effects* / Q000502:physiology; D002645:Chickens; D003345:Corticosterone / Q000378:metabolism; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004333:Drug Administration Routes; D004347:Drug Interactions; D004837:Epinephrine / Q000378:metabolism; D007276:Injections, Intraventricular / Q000379:methods; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology; D013973:Thyrotropin-Releasing Hormone / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013974:Thyroxine / Q000008:administration & dosage / Q000097:blood; D014284:Triiodothyronine / Q000008:administration & dosage / Q000097:blood
D010446:Peptide Fragments; D014284:Triiodothyronine; C104416:astressin; D013973:Thyrotropin-Releasing Hormone; D003346:Corticotropin-Releasing Hormone; D013974:Thyroxine; D003345:Corticosterone; D004837:Epinephrine