Differential effects of Tyr-MIF-1, MIF-1, and naloxone on peptide YY-induced hyperphagia.
Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2) and MIF-1 (Pro-Leu-Gly-NH2) act as opiate antagonists in various behavioral systems including ingestion. Central injection of peptide YY (PYY) elicits a powerful feeding response in satiated rats, and the opioid antagonist naloxone decreases eating in a variety of conditions including PYY-stimulated eating. Therefore, the aim of this study was to examine the effects of Tyr-MIF-1 and MIF-1 as opiate antagonists on a naloxone-sensitive PYY model of hyperphagia. Naloxone at doses of 1.0 and 10.0 mg/kg, SC, decreased hyperphagia induced by 2.4 micrograms PYY injected in the PVN. MIF-1 and Tyr-MIF-1 had no effect on PYY-induced eating at doses comparable to naloxone (0.1 to 10.0 mg/kg, IP). These results suggest that in this model of eating behavior, Tyr-MIF-1 and MIF-1 do not act as opiate antagonists.
Hagan
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MM
Department of Psychology, University of Texas at El Paso 79968-0553.
Moss
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DE
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects; D006963:Hyperphagia / Q000139:chemically induced*; D009075:MSH Release-Inhibiting Hormone / Q000031:analogs & derivatives / Q000494:pharmacology*; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D019894:Peptide YY; D010455:Peptides / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D010455:Peptides; D019894:Peptide YY; D009270:Naloxone; C036930:tyrosyl-prolyl-leucyl-glycinamide; D009075:MSH Release-Inhibiting Hormone