CENTRALLY ADMINISTERED NEUROPEPTIDE-Y ENHANCES THE HYPOTHERMIA INDUCED BY PERIPHERAL ADMINISTRATION OF ADRENOCEPTOR ANTAGONISTS

The distribution of neuropeptide Y in the brain includes extensive coexistence within adrenaline- and noradrenaline-containing neurons and many of its actions are often associated with adrenergic systems. Since neuropeptide Y immunoreactivity is particularly intense in the preoptic area, one of the principal sites for thermoregulation, we have tested the effects of neuropeptide Y on core temperature in normothermic rats, and rats rendered hypothermic by systemic treatment with adrenergic antagonists. In the normothermic rat, intracerebroventricular administration of 1 μg of neuropeptide Y did not have a significant effect on core temperature. Intraperitoneal treatment with the α1-adrenoceptor antagonist, prazosin, or the β-adrenoceptor antagonist, propranolol, caused an immediate and significant hypothermia; the intracerebroventricular administration of 1 μg of neuropeptide Y, 10 minutes after these drugs, strongly potentiated their hypothermic effect. Although intraperitoneal treatment with the α2-adrenoceptor antagonist, idazoxan, had no hypothermic effect per se, the intracerebroventricular administration of NPY 10 minutes after this antagonist led to a significant decrease in core temperature. © 1990.