3.3. Electrophysiological activity analysis
The electrical activity of neurons is an extensive integration of neuronal ion channel function. These ion channel proteins are transported by axons to specific locations to establish neuronal polarity and influence synaptic plasticity.[24]Hence, electrophysiological activity is regarded as a key indicator to inspect whether the neuron is physiological disordered or diseased.[25,26] To explore the effect of gene transfection on the physiological activity of neurons, the electrophysiology assays of non-transfected (Figure 3A) and transfected (Figures 3B and 3D) primary cultured neurons were conducted. Membrane potential was maintained at -60 mV with a current clamp model via adjusting injection current properly range from -10 pA to -15 pA. The stimulus program was run successively from -20 pA to 70 pA by 10 pA steps (Figure 3C). We found that the induced action potential of primary cultured hippocampal neurons took place when the injection current was 30 pA. With the injected current going up, the frequency of evoked action potentials increases (Figure 3E). In the transfected neurons, a similar electrophysiological result was observed (Figure 3F), indicating that the expression of mCherry protein did not affect the physiological state of neurons after transfection. Moreover, the electrophysiological results in combination with the results of the entire axon structure (Figure 1) and microtubule skeleton architecture (Figure 2B), as well as unaffected Tuj-1 expression (Figure S1) after transfection suggested the transfection strategy has a minimal side effect on the physiological state of neurons during the imaging period.