Role of taurine as a possible transmitter in the thermoregulatory pathways of the rat.

Taurine (10 and 20 micrograms) injected unilaterally into the lateral ventricle of rats caused an increase in core temperature. Bilateral injection of taurine 2.5 and 5 micrograms into the preoptic region of the anterior hypothalamus induced a dose-related hyperthermia: higher doses (10 micrograms) caused hypothermia. Intrahypothalamically taurine-induced hyperthermia was blocked by prior injection of strychnine hydrochloride (5 and 15 micrograms); doses which alone had no effect on core temperature. Of the other inhibitory amino acids injected intrahypothalamically hypotaurine also induced a hyperthermia. GABA (10 micrograms) caused hypothermia; glycine (10 micrograms) had no effect. Potassium (50 mM) stimulated release of radioactivity from superfused slices of anterior hypothalamus prelabelled with [3H]taurine in a calcium-dependent manner. A high affinity uptake mechanism with a Km of 8.5 microM was demonstrated with [3H]taurine into slices of anterior hypothalamus. Taurine may have a neurotransmitter role in the anterior hypothalamus but whether the body temperature effects represent physiological or pharmacological events remains to be established.