Exercise-induced Modulation of Ferroptosis: Potential Mechanisms for Improvement in Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder characterized by muscle rigidity, resting tremor, and postural instability, which severely impair the quality of life in middle-aged and elderly individuals. PD's pathogenesis is complex, involving oxidative stress, immune inflammation, and genetic factors. Despite extensive research, precise therapeutic targets for PD remain elusive, necessitating further investigation into its underlying mechanisms. Recent studies highlight the pivotal role of regional brain iron overload, oxidative stress, and lipid peroxidation in PD's pathogenesis. Ferroptosis, a form of regulated cell death driven by iron dependency and lipid peroxidation, has emerged as a critical factor in PD pathology. This review examines the relationship between ferroptosis and PD and explores the potential of exercise as a therapeutic intervention to modulate ferroptosis and alleviate PD symptoms. Ferroptosis, distinct from other forms of cell death such as necrosis, autophagy, pyroptosis, and apoptosis, is characterized by mitochondrial shrinkage, reduced cristae, and membrane collapse, without nuclear fragmentation, DNA cleavage, or caspase activation. It is induced by the accumulation of intracellular Fe2+, which enhances lipid peroxidation and reactive oxygen species (ROS) generation, ultimately leading to cell death. Studies show disrupted iron metabolism in PD patients, with elevated iron levels in dopaminergic neurons of the substantia nigra correlating with disease severity. Iron chelation therapy has shown promise in alleviating PD symptoms by reducing brain iron levels, highlighting the significance of iron metabolism in PD pathogenesis. Lipid peroxidation, a hallmark of ferroptosis, involves the oxidation of polyunsaturated fatty acids (PUFAs) in cell membranes, compromising membrane integrity and increasing permeability. Elevated lipid peroxidation in the substantia nigra contributes to neuronal damage in PD. Enzymes such as ACSL4 and LPCAT3, crucial in PUFA metabolism, play significant roles in ferroptosis. Exercise has been shown to modulate these enzymes, potentially reducing lipid peroxidation and preventing ferroptosis in PD. Glutathione (GSH) metabolism is another crucial factor in ferroptosis regulation. GSH depletion impairs ROS detoxification, exacerbating oxidative stress and lipid peroxidation. PD patients exhibit reduced GSH levels in the substantia nigra, making dopaminergic neurons more vulnerable to oxidative damage. Exercise enhances GSH synthesis and activity, mitigating oxidative stress and ferroptosis in PD. alpha-Synuclein aggregation, a hallmark of PD, is closely linked to iron metabolism and oxidative stress. Excessive alpha-synuclein binds to iron, promoting its aggregation and inducing ferroptosis. Exercise has been found to reduce alpha-synuclein accumulation and its pathological phosphorylation, potentially through the upregulation of neuroprotective proteins like DJ-1 and Irisin. These proteins enhance antioxidant defenses and facilitate alpha-synuclein degradation, providing a protective effect against PD progression. Additionally, glutamate excitotoxicity, driven by dysregulated glutamate metabolism and receptor activity, contributes to ferroptosis in PD. Exercise modulates glutamate levels and receptor expression, reducing excitotoxicity and iron- induced neuronal damage. In conclusion, emerging research suggests that exercise may inhibit ferroptosis through multiple mechanisms, including regulation of iron metabolism, enhancement of antioxidant defenses, reduction of alpha-synuclein aggregation, and modulation of glutamate metabolism. These findings highlight the potential of exercise as a non-pharmacological intervention in the prevention and treatment of PD. Further research is needed to elucidate precise mechanisms and optimize exercise protocols for maximum therapeutic benefit.