title: Evidence for involvement of nitric oxide in pretectal analgesia in rat.
abstract: The study was undertaken to evaluate the role of nitric oxide (NO) in pretectal (PTN)-induced analgesia in rats. Microinjection of varying concentrations of L-arginine (1 nM to 1 microM) produced a quick, long-lasting and concentration-dependent analgesic response, whereas similar concentrations of D-arginine failed to produce analgesia. Moreover pretreatment with N-nitro-L-arginine methyl ester (L-NAME, 1 microM) significantly prevented L-arginine induced analgesia. Further, pretreatment of animals with methylene blue, a known guanylate cyclase inhibitor also prevented the development of analgesia. Our study suggests that L-arginine caused production of NO, which in turn activates pretectal analgesic system involving cyclic GMP.
authors.affiliation: Division of Pharmacology, Central Drug Research Institute, Lucknow, India.
authors.forename: A
authors.initials: A
authors.lastname: Kumar
authors.forename: R
authors.initials: R
authors.lastname: Raghubir
authors.forename: R C
authors.initials: RC
authors.lastname: Srimal
authors.forename: B N
authors.initials: BN
authors.lastname: Dhawan
mesh_terms: D000698:Analgesia; D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D008297:Male; D008636:Mesencephalon / Q000502:physiology*; D008751:Methylene Blue / Q000494:pharmacology; D008845:Microinjections; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000378:metabolism*; D010147:Pain Measurement / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D009569:Nitric Oxide; D001120:Arginine; D006162:Guanylate Cyclase; D008751:Methylene Blue; D019331:NG-Nitroarginine Methyl Ester