Peptidergic regulation of stress-induced eating.
By use of the model of stress-induced (mild tail pinch) eating we have examined the interrelationships of peptides and monoamines responsible for regulating this behavior. We have shown that the synthetic opiate analog, D-Ala2-Met-enkephalinamide (1 microgram), when administered intracerebroventricularly (icv) reverses the suppressive effects of the serotonin agonist, quipazine (40 micrograms icv), the beta-agonist, isoproterenol (40 micrograms icv), and the alpha-antagonist, phentolamine (150 micrograms icv), and partially reversed the effects of atropine (2.5 mg/kg sc) and the dopamine antagonist haloperidol (0.5 mg/kg sc). The opiate antagonist naloxone (10 mg/kg sc) suppressed tail-pinch-induced eating, and this effect could not be reversed by the GABA-agonist muscimol (500 ng icv) nor norepinephrine (20 micrograms icv). The putative satiety hormones cholecystokinin-octapeptide (5 micrograms/kg sc) and bombesin (5 micrograms/kg sc) suppressed stress-induced eating. The suppressive effect of these substances was reversed by a number of known appetite stimulants viz., D-Ala2-Met-enkephalinamide, diazepam, muscimol, and propanolol. Norepinephrine reversed the suppressive effect of bombesin but not that of cholecystokinin. Based on these results we present a hypothetical model to partially explain the peptidergic-monoamine regulation of stress-induced eating.
D000818:Animals; D001067:Appetite Depressants / Q000494:pharmacology; D001285:Atropine / Q000494:pharmacology; D001839:Bombesin / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002766:Cholecystokinin / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives*; D004745:Enkephalins / Q000494:pharmacology; D005247:Feeding Behavior / Q000187:drug effects; D006220:Haloperidol / Q000494:pharmacology; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology*; D010646:Phentolamine / Q000494:pharmacology; D011814:Quipazine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012844:Sincalide; D013315:Stress, Psychological / Q000503:physiopathology*
D001067:Appetite Depressants; D004745:Enkephalins; D010446:Peptide Fragments; D010455:Peptides; D009118:Muscimol; D009270:Naloxone; D011814:Quipazine; D004744:Enkephalin, Methionine; C022118:enkephalinamide-Met, Ala(2)-; D001285:Atropine; D002217:Carbachol; D002766:Cholecystokinin; D006220:Haloperidol; D007545:Isoproterenol; D012844:Sincalide; D001839:Bombesin; D009638:Norepinephrine; D010646:Phentolamine