title: Letter: Cyclic A.M.P. and morphine analgesia.
mesh_terms: D000698:Analgesia; D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism*; D007274:Injections, Intraperitoneal; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013788:Thalamus / Q000187:drug effects*; D013997:Time Factors
chemical_list: D009020:Morphine; D000242:Cyclic AMP