Hypothermia induced in rabbits by intracerebroventricular taurine: specificity and relationships with central serotonin (5-HT) systems.

The intracerebroventricular (i.c.v.) injection of taurine produced a fall in core temperature, the extent of which was dependent on the thermal gradient between the body and the environment. Concurrently, a sudden rise in ear skin temperature, which was maximal in the cold and negligible at 30 degrees C, was observed. The fever induced by i.v. injection of Escherichia coli endotoxin was antagonized by taurine. High temperatures produced by i.c.v. injection of prostaglandin E1 were also suppressed by taurine. Intracerebroventricular injections of bicuculline and strychnine, but not those of picrotoxin or pentylentetrazol, were able to reduce hypothermia induced by taurine. Intracerebroventricular injection of the taurine reuptake inhibitor guanidinoethyl sulfonate, on the contrary, did enhance the hypothermic response to taurine. Injection (i.c.v.) of serotonin (5-HT) elicited a fall in core temperature which was not accompanied by a rise in ear skin temperature, but was antagonized by the concurrent injection of the 5-HT antagonist methysergide. Pretreating animals with p-chlorophenyl-alanine caused a significant fall of brain 5-HT contents and a reduction of the hypothermic response to taurine. The latter effect was also observed when the animals were i.c.v. pretreated either the methysergide or with the 5-HT reuptake blockers chlorimipramine and Lilly 110140. These findings give support to the hypothesis that taurine-induced hypothermia in rabbits mediated by some taurine sensitive cells and, at least in part, by serotonergic synaptic mechanisms.