Endorphinergic and alpha-noradrenergic systems in the paraventricular nucleus: effects on eating behavior.
Brain cannulated rats were injected with the opioid peptide beta-endorphin (beta-EP) directly into the hypothalamic paraventricular nucleus (PVN) where norepinephrine (NE) is most effective in stimulating eating behavior. Beta-Endorphin (1.0 nmole) reliably increased food intake in satiated animals, and this response was blocked by local administration of the selective opiate antagonist naloxone. The eating induced by beta-EP was positively correlated in magnitude with the NE response and, like NE, was antagonized by PVN injection of the alpha-noradrenergic blocker phentolamine. Naloxone had no effect on NE-induced eating, and the dopaminergic blocker fluphenazine failed to alter either beta-EP or NE eating. When injected simultaneously, at maximally effective doses, beta-EP and NE produced an eating response which was significantly larger than either of the responses elicited separately by beta-EP or NE and was essentially equal to the sum of these two responses. The evidence obtained in this study suggests that beta-EP and NE stimulate food ingestion through their action on PVN opiate and alpha-noradrenergic receptors, respectively, and that beta-EP's action is closely related to, and in part may be dependent upon, the PVN alpha-noradrenergic system for feeding control.
D000818:Animals; D003847:Deoxyglucose / Q000494:pharmacology; D004347:Drug Interactions; D004435:Eating / Q000187:drug effects*; D004723:Endorphins / Q000494:pharmacology*; D007031:Hypothalamus / Q000502:physiology; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects*; D010646:Phentolamine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D011957:Receptors, Opioid / Q000187:drug effects*; D001615:beta-Endorphin
D004723:Endorphins; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D011957:Receptors, Opioid; D009270:Naloxone; D001615:beta-Endorphin; D003847:Deoxyglucose; D009638:Norepinephrine; D010646:Phentolamine