title: Morphine and codeine. The analgesic effect in tolerant and non-tolerant rats.
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects; D001923:Brain Chemistry; D003061:Codeine / Q000378:metabolism / Q000494:pharmacology*; D004357:Drug Synergism; D004361:Drug Tolerance; D009020:Morphine / Q000378:metabolism / Q000494:pharmacology*; D009269:Nalorphine / Q000494:pharmacology; D009638:Norepinephrine / Q000032:analysis; D010277:Parasympathomimetics / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000032:analysis
chemical_list: D010277:Parasympathomimetics; D012701:Serotonin; D009020:Morphine; D009269:Nalorphine; D003061:Codeine; D009638:Norepinephrine