| Summary: | <p>Abstract</p> <p>Background</p> <p>The generation of action potential is required for stimulus-evoked neurotransmitter release in most neurons. Although various voltage-gated ion channels are involved in action potential production, the initiation of the action potential is mainly mediated by voltage-gated Na<sup>+</sup> channels. In the present study, differentiation-induced changes of mRNA and protein expression of Na<sup>+</sup> channels, Na<sup>+</sup> currents, and cell membrane excitability were investigated in NG108-15 cells.</p> <p>Results</p> <p>Whole-cell patch-clamp results showed that differentiation (9 days) didn’t change cell membrane excitability, compared to undifferentiated state. But differentiation (21 days) induced the action potential generation in 45.5% of NG108-15 cells (25/55 cells). In 9-day-differentiated cells, Na<sup>+</sup> currents were mildly increased, which was also found in 21-day differentiated cells without action potential. In 21-day differentiated cells with action potential, Na<sup>+</sup> currents were significantly enhanced. Western blot data showed that the expression of Na<sup>+</sup> channels was increased with differentiated-time dependent manner. Single-cell real-time PCR data demonstrated that the expression of Na<sup>+</sup> channel mRNA was increased by 21 days of differentiation in NG108-15 cells. More importantly, the mRNA level of Na<sup>+</sup> channels in cells with action potential was higher than that in cells without action potential.</p> <p>Conclusion</p> <p>Differentiation induces expression of voltage-gated Na<sup>+</sup> channels and action potential generation in NG108-15 cells. A high level of the Na<sup>+</sup> channel density is required for differentiation-triggered action potential generation.</p>
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