[Secretion of TRH in the third cerebral ventricle during acute cold exposure in the unanesthetized rat. Effect of alpha-adrenergic drugs].
The concentrations of TRH in the cerebrospinal fluid (CSF) of the 3rd ventricle were measured with push-pull cannulae in 12 conscious rats. In the basal state the level of TRH in 15 min perfusion samples (210 microliters) were low (2.69 +/- 0.05 pg) and mostly undetectable with the RIA available. However, 70 to 80 min after exposure of the rats to cold (4 degrees C) a short lived but significant rise of TRH was measured in all animals. Post cold peaks amounted to 5.15 +/- 0.5 pg/15 min (p less than 0.001 vs baseline levels). This cold response to CSF TRH was influenced neither by pretreatment of rats with the alpha-adrenergic blocker phentolamine, administered i.p. (40 mg/kg) or i. c. v. (10(-5) M) 1 h before cold exposure, nor by i. c. v. infusion of the alpha 1-adrenergic blocker prazosin (10(-5) M). In rats receiving the blockers the post-cold TRH peaks were 6.76 +/- 1.61 pg/15 min and 5.70 +/- 0.70 pg/15 min, respectively. The possible origin of CSF TRH and the resistance of its cold stimulation to alpha-adrenergic blockers, compared to TRH released into the median eminence are discussed.
D000818:Animals; D002552:Cerebral Ventricles / Q000378:metabolism*; D003080:Cold Temperature; D008297:Male; D010646:Phentolamine / Q000494:pharmacology*; D011224:Prazosin / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013973:Thyrotropin-Releasing Hormone / Q000134:cerebrospinal fluid*
D013973:Thyrotropin-Releasing Hormone; D011224:Prazosin; D010646:Phentolamine
Sécrétion de TRH dans le troisième ventricule cérébral lors de l'exposition aiguë au froid chez le rat non anesthésié. Effet des drogues alpha-adrénergiques.