title: Opiate receptor-natural ligand system: causal factor or defense system?
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D004745:Enkephalins / Q000502:physiology; D006801:Humans; D008024:Ligands; D001523:Mental Disorders / Q000209:etiology / Q000517:prevention & control; D008954:Models, Biological; D051381:Rats; D011957:Receptors, Opioid; D013315:Stress, Psychological
chemical_list: D004745:Enkephalins; D008024:Ligands; D011957:Receptors, Opioid