Neurotropin inhibits neuronal activity through potentiation of sustained K currents in primary cultured DRG neurons.

Neurotropin (NTP) is a Japanese analgesic agent for treating neuropathic pain; however, its method of action remains unclear. This study examined the effects of NTP on the activity of small dorsal root ganglion (DRG) neurons using whole-cell patch clamp recordings. After 3 days of treatment, NTP decreased current injection-induced firing activity of cultured DRG neurons by raising the current threshold for action potential generation. Additionally, NTP increased the sustained component of voltage-gated potassium (K) channel currents without affecting other K currents. These results suggest that NTP inhibits the firing activity of DRG neurons through augmentation of sustained K current.