Dopamine receptor subtypes modulate the excitability of dorsal root ganglion neurons

Dorsal root ganglion (DRG) neurons serve as the first-order sensory neurons relaying peripheral inputs to the spinal cord. Studies have shown that dopaminergic signalling contributes to the modulation of DRG neurons excitability and nociceptive transmission. In this study, we examined the effects of dopamine receptor subtypes on the excitability of small and large-sized DRG neurons using whole-cell patch-clamp recordings in acutely cultured rat DRG neurons. Activation of D1-like receptors by SKF38393 caused a depolarizing shift in the action potential threshold in small sized DRG neurons whereas an increase in spike width was observed in both small and large sized DRG neurons, suggesting reduced excitability likely mediated through modulation of sodium channel activity, whereas activation of D2-like receptors by ropinirole reduced the action potential amplitude and modulated the repolarization dynamics in small sized DRG neurons, indicating potential involvement of Gi-coupled mechanisms affecting sodium and potassium currents. Together, these findings demonstrate subtype-specific modulation of DRG neurons excitability by dopamine and highlight the peripheral dopaminergic system as a critical regulator of nociceptive signalling with potential implications for pain management.