title: Down regulation of hypothalamic proopiomelanocortin system during morphine tolerance.
mesh_terms: D000818:Animals; D004361:Drug Tolerance; D004723:Endorphins / Q000378:metabolism; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism*; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D011333:Pro-Opiomelanocortin / Q000378:metabolism*; D051381:Rats; D001615:beta-Endorphin
chemical_list: D004723:Endorphins; D004744:Enkephalin, Methionine; D001615:beta-Endorphin; D011333:Pro-Opiomelanocortin; C027511:enkephalin-Met, Arg(6)-Phe(7)-; D009020:Morphine