title: Letter: Cyclic A.M.P., substance P, and morphine analgesia.
mesh_terms: D000698:Analgesia; D000242:Cyclic AMP / Q000096:biosynthesis*; D006801:Humans; D066298:In Vitro Techniques; D009020:Morphine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D013373:Substance P / Q000502:physiology*; D013788:Thalamus / Q000187:drug effects / Q000378:metabolism
chemical_list: D013373:Substance P; D009020:Morphine; D000242:Cyclic AMP