RESUMEN
Systemic administration of the dietary constituent, resveratrol, was previously shown to inhibit the nociceptive jaw-opening reflex (JOR) via the endogenous opioid system. The present study investigated whether resveratrol could similarly affect the JOR under in vivo conditions via 5HT3 receptor-mediated GABAergic inhibition. We used electrical stimulation of the tongue in pentobarbital-anesthetized rats to evoke the JOR, which was recorded as the anterior belly of the digastric muscle electromyograms (dEMG). Intravenous administration of resveratrol (2â¯mg/kg) reduced the dEMG amplitude in response to three times the determined threshold electrical stimulation, with maximum inhibition reached within approximately 10â¯min. These inhibitory effects on the JOR were reversible to control levels after approximately 20â¯min. Pretreatment of rats with either 5HT3 receptor antagonist, ondansetron (0.25-1â¯mg/kg, i.p.), or GABAA receptor antagonist, bicuculline (0.5-1â¯mg/kg, i.p.), significantly and dose-dependently attenuated the inhibitory effects of resveratrol on dEMG amplitude compared with untreated controls. These findings suggest that resveratrol also attenuates the nociceptive JOR via 5HT3 receptor-mediated GABAergic inhibition. The present study therefore provides new insight into a possible mechanism underlying resveratrol-induced trigeminal antinociception via the descending pain control system and highlights a potential therapeutic agent for complementary alternative medicine.