Effects of thyrotropin releasing hormone injections into different loci of rat brain on core temperature

Intracerebral administration of thyrotropin releasing hormone (0.625--80 micrograms) induces moderate hyperthermia in Sprague--Dawley rats. The effect is more pronounced in the medical preoptic nucleus than in the lateral preoptic nucleus, n. accumbens, lateral ventricle and other regions. It lasts longer, however, in the n. accumbens. There is no effect in the stria terminalis. Hyperthermia is probably of central origin since intraperitoneal administration (20--80 mg/kg) under the same conditions has no clear effect.