RESUMO
As a promising flavonoid, naringenin has shown potential anti-inflammatory and antioxidant properties mainly in inflammatory pain models by oral administration. Therefore, we investigated the antinociceptive activity of this compound by intraperitoneally (i.p.) administration, as well as, associated mechanism of action considering the involvement of L-arginine/nitric oxide (NO)/cyclic GMP (cGMP)/potassium channel (KATP) pathway and opioid receptors. The antinociceptive effect of naringenin was evaluated in male NMRI mice using formalin test at early and late phases. To assess the involvement of L-arginine/NO/cGMP/KATP pathway and opioid receptors, mice were pretreated i.p. with L-arginine (NO precursor), S-nitroso-N-acetylpenicillamine (SNAP, NO donor), N(gamma)-nitro-L-arginine methyl ester (L-NAME, inhibitor of nitric oxide synthase), sildenafil (inhibitor of phosphodiesterase enzyme), glibenclamide (KATP channel blocker) and naloxone (an opioid receptor antagonist), respectively 20 min before administration of the most effective dose of naringenin. Naringenin showed a dose-dependent antinociceptive effect at both early and late phases of the formalin test. The dose of 100 mg/kg of naringenin was identified as the most effective dose and selected for further experiments. Our mechanistic evaluations showed that L-arginine, SNAP and sildenafil could enhance the antinociceptive effects of naringenin, revealing the critical role of NO and cGMP during its antinociceptive effect. On the other hand, glibenclamide and naloxone could mitigate the antinociceptive potential of naringenin at both phases of formalin test, which confirmed the associated role of KATP channels and opioid receptors. In conclusion, naringenin could be a promising antinociceptive agent acting through opioid receptors and L-arginine/NO/cGMP/KATP channel pathway.