cyclic-gmp and nimesulide

Bradykinin B2 receptor-deleted mice (Bdkrb2(-/-)) have delayed carotid artery thrombosis times and prolonged tail bleeding time resulting from elevated angiotensin II (AngII) and angiotensin receptor 2 (AT2R) producing increased plasma nitric oxide (NO) and prostacyclin. Bdkrb2(-/-) also have elevated plasma angiotensin-(1-7) and messenger RNA and protein for its receptor Mas. Blockade of Mas with its antagonist A-779 in Bdkrb2(-/-) shortens thrombosis times (58 ± 4 minutes to 38 ± 4 minutes) and bleeding times (170 ± 13 seconds to 88 ± 8 seconds) and lowers plasma nitrate (22 ± 4 μM to 15 ± 5 μM), and 6-keto-PGF1α (259 ± 103 pg/mL to 132 ± 58 pg/mL). Bdkrb2(-/-) platelets express increased NO, guanosine 3',5'-cyclic monophosphate, and cyclic adenosine monophosphate with reduced spreading on collagen, collagen peptide GFOGER, or fibrinogen. In vivo A-779 or combined L-NAME and nimesulide treatment corrects it. Bdkrb2(-/-) platelets have reduced collagen-related peptide-induced integrin α2bβ3 activation and P-selectin expression that are partially corrected by in vivo A-779, nimesulide, or L-NAME. Bone marrow transplantations show that the platelet phenotype and thrombosis time depends on the host rather than donor bone marrow progenitors. Transplantation of wild-type bone marrow into Bdkrb2(-/-) hosts produces platelets with a spreading defect and delayed thrombosis times. In Bdkrb2(-/-), combined AT2R and Mas overexpression produce elevated plasma prostacyclin and NO leading to acquired platelet function defects and thrombosis delay.

Topics: Angiotensin I; Angiotensin II; Animals; Bleeding Time; Blood Platelets; Bone Marrow Transplantation; Cyclic AMP; Cyclic GMP; Epoprostenol; Immunoblotting; Mice; Mice, 129 Strain; Mice, Knockout; NG-Nitroarginine Methyl Ester; Nitric Oxide; Peptide Fragments; Platelet Aggregation Inhibitors; Platelet Membrane Glycoproteins; Proto-Oncogene Mas; Proto-Oncogene Proteins; Receptor, Angiotensin, Type 2; Receptor, Bradykinin B2; Receptors, G-Protein-Coupled; Reverse Transcriptase Polymerase Chain Reaction; Sulfonamides; Thrombosis; Time Factors

Peripheral activation of the NO-cGMP pathway has been implicated in various nociceptive conditions. The antinociceptive effect of the PDE-5 inhibitor, sildenafil, alone or in combination with cyclooxygenase inhibitor diclofenac and nimesulide, was assessed in the different animal models of peripheral nociception. In the present study we investigated the possible interaction between cyclooxygenase and NO-cGMP pathway in writhing assay and carrageenan-induced hyperalgesia in mice and rats, respectively. Sildenafil [1-2 mg/kg, i.p. or 50-100 microg/paw, intraplantar (i.pl.)], nimesulide (1-2 mg/kg, i.p. or 25-50 microg/paw, i.pl.) and diclofenac (1-2 mg/kg, i.p. or 25-50 microg/paw, i.pl.) exhibited an antinociceptive effect in both the models. When ineffective doses of sildenafil (0.5 mg/kg, i.p and 25 microg/paw, i.pl.) were co-administered with ineffective doses of nimesulide (0.5 mg/kg, i.p. and 10 microg/paw, i.pl.) and diclofenac (0.5 mg/kg, i.p. and 10 microg/paw, i.pl.), there was a significant increase in the antinociceptive effect in both the models of peripheral nociception. Further, the potentiation of the effect was blocked by L-NAME (20 mg/kg, i.p., 100 microg/paw, i.pl.), a non-selective NOS inhibitor and methylene blue (1 mg/kg, i.p.), a guanylate cyclase inhibitor. L-NAME or methylene blue itself had little or no effect on both the models of hyperalgesia. These results suggest that cyclooxygenase, NO and cGMP are relevant in the combination-induced antinociception. In conclusion, sildenafil induced antinociception, and its potentiation of the effect of the cyclooxygenase inhibitors nimesulide and diclofenac was probably mediated through the activation of the NO-cGMP pathway and inhibition of cyclic GMP degradation.

Topics: Animals; Carrageenan; Cyclic GMP; Cyclooxygenase Inhibitors; Diclofenac; Drug Synergism; Enzyme Inhibitors; Female; Male; Mice; NG-Nitroarginine Methyl Ester; Pain; Phosphodiesterase Inhibitors; Piperazines; Purines; Rats; Rats, Wistar; Sildenafil Citrate; Sulfonamides; Sulfones

The involvement of the nitric oxide-cyclic GMP pathway in the peripheral antinociception induced by the COX-2 preferential inhibitor nimesulide was assessed by using the formalin test in the rat. Intraplantar administration of nimesulide in the formalin-injured paw produced a significant antinociceptive effect that was due to a local action, because nimesulide administration in the contralateral paw was ineffective. Local pretreatment of the paws with saline or N(G)-D-nitro-arginine methyl ester (D-NAME, the inactive isomer of L-NAME) did not affect the antinociception produced by nimesulide. However, local administration of L-NAME (a nitric oxide synthesis inhibitor) or 1H-(1,2,4)-oxadiazolo(4, 2-a)quinoxalin-1-one (ODQ, a soluble guanylyl cyclase inhibitor) blocked the effect of nimesulide. Moreover, the antinociceptive effect of local nimesulide was potentiated by the coadministration of 3-morpholino-sydnonimine-HCl (SIN-1, a nitric oxide donor). It is concluded that nimesulide produces antinociception by a peripheral mechanism of action requiring activation of the nitric oxide-cyclic GMP pathway at the local level.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Cyclic GMP; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Female; Isoenzymes; NG-Nitroarginine Methyl Ester; Nitric Oxide; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Wistar; Sulfonamides