Abstract
BACKGROUND: Cochlear implant-based electrical stimulation may be an important reason to induce the residual hearing loss after cochlear implantation. In our previous study, we found that charge-balanced biphasic electrical stimulation inhibited the neurite growth of spiral ganglion neurons (SGNs) and decreased Schwann cell density in vitro. In this study, we want to know whether cochlear implant-based electrical stimulation can induce the change of electrical activity in cultured SGNs. METHODS: Spiral ganglion neuron electrical stimulation in vitro model is established using the devices delivering cochlear implant-based electrical stimulation. After 48 h treatment by 50 μA or 100 μA electrical stimulation, the action potential (AP) and voltage depended calcium current (I (Ca)) of SGNs are recorded using whole-cell electrophysiological method. RESULTS: The results show that the I (Ca) of SGNs is decreased significantly in 50 μA and 100 μA electrical stimulation groups. The reversal potential of I (Ca) is nearly +80 mV in control SGN, but the reversal potential decreases to +50 mV in 50 μA and 100 μA electrical stimulation groups. Interestingly, the AP amplitude, the AP latency, and the AP duration of SGNs have no statistically significant differences in all three groups. CONCLUSION: Our study suggests cochlear implant-based electrical stimulation only significantly inhibit the I (Ca) of cultured SGNs but has no effect on the firing of AP, and the relation of I (Ca) inhibition and SGN damage induced by electrical stimulation and its mechanism needs to be further studied.