Chronic and continuous intracerebroventricular infusion of neuropeptide Y in Long-Evans rats mimics the feeding behaviour of obese Zucker rats.

Neuropeptide Y (NPY), a member of the pancreatic polypeptide family, strongly stimulates food intake when injected centrally in animals. It is found in abundance in the brain and particularly in areas involved in the regulation of feeding behaviour. Moreover, in these areas, NPY concentrations are higher in the obese hyperphagic Zucker rat. The aim of the present experiment was to reproduce in normal Long-Evans rats the high central levels of NPY measured in Zucker rats. We therefore continuously infused NPY in the brain lateral ventricle through osmotic mini-pumps and studied the effects of this infusion on different parameters of the feeding behaviour. Male adult Long-Evans rats were fed ad libitum on a high carbohydrate (HC) diet and on a high fat (HF) diet given simultaneously in two separate cups. NPY was infused at a rate of 0.44 micrograms/h (n = 11) and rats infused with artificial cerebrospinal fluid (n = 11) served as controls. The infusions lasted 14 days. Total food intake markedly increased in NPY infused rats starting on the first day after pump installation (33.7 +/- 1.7 vs. 14.8 +/- 0.6 g/day; P less than 0.0001). This effect lasted for nine days. In these rats, the average food intake during the infusion period (21.0 +/- 1.6 g/day) was also significantly greater than during the pre-infusion period (13.1 +/- 0.5 g/day; P less than 0.0001) and the post-infusion period (10.6 +/- 0.4 g/day; P less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)