L-Arginine-No System Participates in the Analgesic Effect of Flunixin Meglumine in the Rat

Abstract

This study investigated whether the L-arginine-NO system participates in the analgesic effect of fl unixin meglumine in the rat. Hyperalgesia was induced by intraplantar (i.pl.) administration of carrageenan (500 μg) into the rat's hind paw. Electronic von Frey apparatus was used to determine paw withdrawal threshold induced by pressure as the painful stimulus, measured in grams (g). Flunixin meglumine (FM; 0.09-0.1 mg/kg; s.c.) and N G -nitro-L-arginine methyl ester (L-NAME; 10 mg/kg; i.p.), given separately as a pre-treatment, i.e. 15 min before i.pl. injection of carrageenan, produced a signifi cant antinociception. When FM (0.09 mg/kg) and a sub-effective dose of L-NAME (5 mg/kg) were co-administered, the antinociceptive effect was signifi cantly increased in comparison with the effect of FM alone. L-arginine (L-ARG;10 mg/kg; i.p.) itself did not produce signifi cant effect on carrageenan-induced hyperalgesia, but signifi cantly reduced the antinociceptive effects of both FM and FM + L-NAME combination. The inhibition of the production of NO might be involved in the mechanism of the analgesic effect of FM.

Involvement of serotonergic, noradrenergic and gabaergic systems in the antinociceptive effect of a ketamine-magnesium sulfate combination in acute pain

“…The differences between the corresponding means in tail-withdrawal latency were verifi ed using one-way analysis of variance (ANOVA), followed by Tukey's HSD post hoc test [25]. A p<0.05 was considered to be statistically signifi cant.…”