Effect of the body temperature upon central administration of substance P--the role of adrenalectomy and GABA-activation.

The change in the body temperature of rats when substance P (SP) is centrally administered is studied by using preimplanted cannules in the preoptic anterior part of the hypothalamus, both in norm and after adrenalectomy, as well as the change of this effect upon preliminary central administration of the GABAA-agonist muscimol. Substance P causes a rise in the temperature, which was significantly less manifested in the adrenalectomized animals. When the animals were pretreated with muscimol in a dose not affecting the temperature when applied independently, the SP-induced rise in the temperature was significantly less manifested in the nonadrenalectomized rats compared with the effect of independent SP administration to nonadrenalectomized animals, though significantly more pronounced compared with the effect of independent administration of SP to adrenalectomized rats. These results suggest the existence of an interaction between the GABA-ergic and the SP-ergic systems and the role of the suprarenal gland for the SP-induced hyperthermia.