The inhibitory effect of a variety of substances on feeding induced by norepinephrine (20 μg ICV) was studied. Subcutaneous administration of the opiate antagonist, naloxone, inhibited norepinephrine-induced eating at 10 and 5 mg/kg, but not a 1 mg/kg. Intraventricular administration of the GABA antagonist, bicuculline, produced a dose related decrease in food ingestion. The putative satiety hormones, bombesin (10 μg/kg; subcutaneously) and cholecystokinin octapeptide ( 10 gmg/kg; subcutaneously) also reduced norepinephrine induced eating, as did ICV administration of calcitonin (2 units). Neither thyrotropin-releasing hormone (1 μg ICV) nor its metabolits, histidyl-proline diketopiperazine (1 μg ICV) altered norepinephrine-induced feeding. The studies reported here suggest a neuromodulatory role of peptides in the central regulation of norepinephrine-induced feeding.
- Histidyl-proline diketopiperazine