Interrelationships between mu opioid and melanocortin receptors in mediating food intake in rats.
The present study examined the interrelationships between feeding responses produced by mu opioid receptor agonists and melanocortin-3 or 4 (MC-3/4) receptor antagonists. Feeding induced by the mu-sensitive opioid peptide, beta-endorphin (betaEND, 10 microg, i.c.v.) was significantly and dose-dependently reduced by pretreatment with the MC-3/4 receptor agonist, melanotan-II (MTII: 0.01-10 nmol, i.c.v.). Moreover, the selective mu opioid antagonist, beta-funaltrexamine (betaFNA: 2-20 mug, i.c.v.), significantly and dose-dependently reduced feeding and weight gain elicited by the potent MC-3/4 receptor antagonist, SHU-9119 (0.5 nmol, i.c.v.), especially at those intake periods (24-48 h) when SHU-9119 produced maximal ingestive effects. These data extend previous findings demonstrating interactions between opioid and melanocortin receptors in the mediation of food intake.
Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, USA.
Henya C
HC
Grossman
Maria M
MM
Hadjimarkou
Robert M
RM
Silva
Silvia Q
SQ
Giraudo
Richard J
RJ
Bodnar
D000818:Animals; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000494:pharmacology; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044101:Receptors, Melanocortin / Q000187:drug effects / Q000502:physiology*; D017450:Receptors, Opioid, mu / Q000187:drug effects / Q000502:physiology*; D001615:beta-Endorphin / Q000187:drug effects
D009292:Narcotic Antagonists; D044101:Receptors, Melanocortin; D017450:Receptors, Opioid, mu; C103272:SHU 9119; D009271:Naltrexone; D001615:beta-Endorphin; C024524:beta-funaltrexamine; D009074:Melanocyte-Stimulating Hormones