Glutathione Decreases Parkinsonism‐Induced Ferroptosis and Oxidative Stress Through the Inhibition of the <scp>TRPM2</scp> Channel in Neuronal Cells

Parkinson's disease (PD) is the most prevalent neurodegenerative disease. Previously, it was believed that aberrant iron metabolism, leading to ferroptosis due to glutathione (GSH) depletion, excessive Ca²⁺ influx, mitochondrial (mROS), and cytosolic (cROS) free reactive oxygen species in the brain, was a contributing factor to PD. ADP-ribose (ADPR), mROS, and cROS activate the TRPM2 cation channel. It is yet unclear how TRPM2 contributes to the development of neuronal damage induced by the rise in ferroptosis in PD. Our aim in this study was to examine the function of TRPM2 and the protective effect of GSH in the dopaminergic human SH-SY5Y neuronal cells that had been exposed to 1-methyl 4-phenylpyridinium (MPP) to produce parkinsonism. The SH-SY5Y cells were divided into six groups: control, MPP, MPP + erastin, MPP + erastin + ferrostatin-1, MPP + erastin + glutathione (GSH), and MPP + erastin + TRPM2 blocker (ACA). In the MPP and MPP + erastin groups, the concentrations of Ca²⁺, ADPR-induced TRPM2 current density, mitochondrial membrane dysfunction, mROS, cROS, lipid peroxidation, mitochondrial Zn²⁺, cytosolic Zn²⁺, and cytosolic Fe²⁺ were increased, although glutathione peroxidase, GSH, cell viability, and cell number were decreased. The changes were higher in the MPP + erastin group than in MPP group only. However, their concentrations were modulated by the changes in the MPP + erastin + ferrostatin-1, MPP + erastin + GSH, and MPP + erastin + ACA groups. In conclusion, the increase in death and ferroptosis in parkinsonism (MPP)-induced SH-SY5Y cells was attributed to TRPM2 activation. By regulating cytosolic oxidant/antioxidant balance, GSH regulates TRPM2 channel activity and lowers neuronal death and ferroptosis.