The role of dopaminergic pathways in thermoregulation in the rabbit.

Dopamine, when injected into the anterior hypothalamus of the rabbit, induced a slight hyperthermia due to an upward shift of the threshold central temperature for induction of cold thermogenesis, panting and vasodilation. A slightly reduced thermosensitivity of the controller regulating vasodilation may also contribute to the hyperthermic effect of dopamine. Intrahypothalamic injections of the dopamine agonist, apomorphine, induced a similar effect to that of dopamine, with the exception that the thermosensitivity of the controller regulating vasodilation was not changed. Intraperitoneal injections of a dopamine antagonist, haloperidol, induced a marked hypothermia, due to a downward shift of the threshold central temperature for induction of cold thermogenesis, panting and vasodilation. A slightly reduced thermosensitivity of the controller regulating vasodilation was also observed. Intrahypothalamic injections of haloperidol did not induce an antagonist effect to dopamine, but rather tended to induce hyperthermia. Thermoregulatory responses, occurring after administration of dopamine or apomorphine, partially resembled those seen after administration of neurotensin or prostaglandins.