Bimodal effect of neuropeptide Y on feeding, and its antagonism by receptor blocking agents in rats.
Satiated rats received intracerebroventricular (icv.) injections of several doses of neuropeptide Y (NPY) and the food intake was measured in the following 4 h. The peptide exerted a dose-dependent biphasic effect; the 100 dose significantly suppressed the food intake, but doses of 1 microgram and 5 micrograms stimulated feeding. After the injection of 2 microliters NPY-antiserum (icv., 1:50 dilution), the cumulative food intake decreased significantly in the first 24 h. From the drugs tested the alpha-1-antagonist prazosine (4 micrograms icv.) and the opiate antagonist naloxone (NX, 0.5 micrograms, icv.) selectively inhibited the feeding-stimulatory effect a high icv. dose of NPY. The alpha-2-antagonist yohimbine (4 micrograms icv.) and the non-selective beta-antagonist propranolol (5 micrograms icv.) did not influence either effect of NPY on feeding. The results suggest the involvement of alpha-1-adrenergic and opiate receptors in the food intake-stimulatory effect of a large icv. dose of NPY. The food intake-inhibitory effect of a low icv. peptide dose was not selectively antagonized by the receptor blocking agents used.
Borisova
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EV
Department of Pathophysiology, Szent-Györgyi Albert University, Szeged, Hungary.
Kadar
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T
Telegdy
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D000818:Animals; D000906:Antibodies / Q000008:administration & dosage; D001921:Brain / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects*; D007276:Injections, Intraventricular; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D009478:Neuropeptide Y / Q000037:antagonists & inhibitors / Q000276:immunology / Q000494:pharmacology*; D011224:Prazosin / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism; D011957:Receptors, Opioid / Q000378:metabolism
D000906:Antibodies; D009478:Neuropeptide Y; D011942:Receptors, Adrenergic, alpha; D011957:Receptors, Opioid; D009270:Naloxone; D011224:Prazosin