Fig. 2

Main categories of noninvasive electrical stimulation (NES) and possible neuroprotective mechanisms underlying the effects. The cellular structure in the figure represents an enlarged image of the retina. Gray cells represent damaged cells in retinal diseases. It has been discovered that NES protects the structure and function of retinal ganglion cells and photoreceptors and has a positive effect on other cell components, including Müller cells, and microglia. The neuroprotective effect of NES involved a variety of mechanisms, including neuro-nutrition (No. ①, green), alleviation of inflammation (No. ②, blue), and inhibition of apoptosis (No. ③, pink). The red upward arrow represents upregulation, while the blue downward arrow represents downregulation. CNTF ciliary neurotrophic factor, BDNF brain-derived neurotrophic factor, bFGF basic fibroblast growth factor, FGF-2 fibroblast growth factor 2, IGF-1 insulin-like growth factor 1, GS glutamine synthetase, p-TrkB phosphorylated tyrosine kinase receptor B, p-NFκB-p65 phosphorylated nuclear factor-κB-p65, TNF-α tumor necrosis factor-α, IL-6 interleukin 6, COX-2 cyclooxygenase-2, IL-10 interleukin 10, Bcl-2 B-cell lymphoma-2, Bax BCL-2-associated X protein