MODIFICATION OF ANTINOCICEPTIVE ACTION OF UKRAIN BY ENDOGENOUS NITRIC OXIDE IN THE WRITHING SYNDROME TEST IN MICE

JAGIELLO-WÓJTOWICZ E., KLEINROK Z., CHODKOWSKA A., SZKODZIAK A., SIEMBIDA E., GUSTAW K., URBANSKA E.

Department of Pharmacology and Toxicology, Medical University School, Lublin, Poland.

Address for correspondence: E. Jagiello-Wojtowicz, Department of Pharmacology and Toxicology, Medical University School, Jaczewskiego 8, 20-090 Lublin, Poland.

Summary: The effects of L-arginine, the physiological precursor of nitric oxide (NO), and inhibitors of NO-synthase on the antinociceptive action of Ukrain (4.75, 9.5, and 19.0 mg/kg i.p.) were investigated using the writhing syndrome test in mice. It was found that L-arginine (0.1 or 1.0 mg/kg i. p.) significantly decreased or enhanced the antinociceptive effect of Ukrain, depending on the combination administered. In addition, the inhibitors of NO-synthase NG-nitro-L-argίnine methyl ester (L-NAME) (1.0 and 10 mg/kg i. p.), 7-nitroindazole (1.0 mg/kg i. p.) and NG-monomethyl-L-arginine acetate (L-NMMA) (1.0 mg/kg i. p.) significantly enhanced Ukrain-induced antinociception. These results suggest that endogenous NO can modify the antinociceptive effect of Ukrain.