Effect of paraventricular injection of neuropeptide Y on milk and water intake of preweanling rats.
This study investigated the effect of paraventricular nucleus (PVN) injection of neuropeptide Y (NPY) on milk and water intake of 2- and 15-day-old sated rats. On the day prior to testing, rat pups were removed from their mothers and implanted with a cannula directed unilaterally at the PVN. On the following day, each pup was implanted with an intra-oral cannula for oral infusion of milk or water that could be swallowed or rejected. Following a 1-hour period fo satiation, each pup received a PVN injection of saline or a single dose of NPY (23.5-235.0 pmol). Milk or water intake was then assessed in a 1-hour test period. Injection of NPY into the PVN enhanced milk and water intake equally at 2 days of age. At 15 days, NPY produced a significantly greater enhancement of milk than water intake. These findings, which are similar to those observed previously with PVN injections of norepinephrine (NE), suggest that: (1) NPY receptors in the PVN, like alpha 2-noradrenergic receptors, are functional very early in the postnatal development of the rat; (2) NPY, in addition to its orexigenic effect, produces a small but significant dipsogenic effect; and (3) NPY may function cooperatively with NE in the PVN to stimulate feeding and drinking beginning at a very early age.
Capuano
C A
CA
Department of Psychology, Fairleigh Dickinson University, Teaneck, NJ 07666.
Leibowitz
S F
SF
Barr
G A
GA
D000818:Animals; D000833:Animals, Suckling; D004326:Drinking / Q000187:drug effects*; D005260:Female; D007267:Injections; D008297:Male; D008892:Milk; D009478:Neuropeptide Y / Q000008:administration & dosage*; D010286:Paraventricular Hypothalamic Nucleus; D051381:Rats; D014867:Water; D015430:Weight Gain / Q000187:drug effects
D009478:Neuropeptide Y; D014867:Water