Activation of ATP-sensitive potassium channels antagonize nociceptive behavior and hyperexcitability of DRG neurons from rats

BACKGROUND Nociceptive responses to noxious stimuli are initiated at peripheral nociceptor terminals. Ion channels play a vital role in pain signal initiation and conduction. Activation of KATP channels has been implicated in mediating the analgesic effects of agents such as morphine. However, systematic studies regarding the effects of KATP activators on nociception and neuronal excitability are scarce. RESULTS In this study, we describe the antagonistic effects of KATP activators pinacidil and diazoxide on nocifensive behavior induced by bradykinin (BK), thermo and mechanical stimuli, and the bradykinin-induced hyperexcitability of DRG neurons. We also found that KATP activators can moderately activate KATP in DRG neurons. Because the effects of KATP activators can be reversed by the KATP blocker glyburide, direct activation of KATP is most likely the underlying mechanism. CONCLUSION This systematic study clearly demonstrates that activation of KATP could have significant modulatory effects on the excitability of sensory neurons and thus on sensory behaviors, such as nociception. KATP activators can be evaluated clinically for the treatment of pain symptoms.