title: Opioid antagonists, endogenous ligands and nociception.
mesh_terms: D000818:Animals; D008024:Ligands; D051379:Mice; D009020:Morphine / Q000037:antagonists & inhibitors; D009043:Motor Activity / Q000187:drug effects; D009292:Narcotic Antagonists / Q000494:pharmacology*; D010146:Pain / Q000503:physiopathology*; D011930:Reaction Time / Q000187:drug effects; D011957:Receptors, Opioid / Q000378:metabolism
chemical_list: D008024:Ligands; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D009020:Morphine