Increased immunoreactive dynorphin and leu-enkephalin in posterior pituitary of obese mice (ob/ob) and super-sensitivity to drugs that act at kappa receptors.
Posterior pituitaries of obese mice (ob/ob) contained significantly more immunoreactive dynorphin (P less than .01) and leu-enkephalin (P less than .01) than their lean littermates. Drinking in obese mice was stimulated by 0.3%, and feeding by 10%, of the dose of ethylketocyclazocine, a kappa receptor agonist, needed to produce extra feeding and drinking in lean mice. Obese mice also showed greater and longer lasting suppression of ingestion after MR-2266, a kappa antagonist, than did lean mice. MR-2266 was much more effective than naloxone in suppressing schedule-induced polydipsia in rats. These results indicate that kappa receptors are involved in feeding and drinking and that obesity is associated with changes in these receptors and their ligands.
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001575:Benzomorphans / Q000031:analogs & derivatives / Q000494:pharmacology*; D003496:Cyclazocine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004326:Drinking / Q000187:drug effects; D004399:Dynorphins; D004435:Eating / Q000187:drug effects; D004723:Endorphins / Q000378:metabolism*; D004743:Enkephalin, Leucine / Q000378:metabolism*; D016314:Ethylketocyclazocine; D005260:Female; D051379:Mice; D008820:Mice, Obese; D009019:Morphinans / Q000494:pharmacology*; D009765:Obesity / Q000503:physiopathology; D010904:Pituitary Gland, Posterior / Q000187:drug effects / Q000378:metabolism*; D011957:Receptors, Opioid / Q000187:drug effects / Q000502:physiology*; D017473:Receptors, Opioid, kappa
D000701:Analgesics, Opioid; D001575:Benzomorphans; D004723:Endorphins; D009019:Morphinans; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; C027247:MR 2266; D016314:Ethylketocyclazocine; D004743:Enkephalin, Leucine; D004399:Dynorphins; D003496:Cyclazocine