Effects of Calcium Ion Dyshomeostasis and Calcium Ion-Induced Excitotoxicity in Parkinson's Disease

Calcium ions (Ca2+) are vital intracellular messengers that regulate a multitude of neuronal functions, including synaptic transmission, plasticity, exocytosis, and cell survival. Neuronal cell death can occur through a variety of mechanisms, including excitotoxicity, apoptosis, and autophagy. In the context of excitotoxicity, the excessive release of glutamate in the synapses can trigger the activation of postsynaptic receptors. Upon activation, Ca2+ influx into the cell from the extracellular space via their associated ion channels, most notably L-type Ca2+ channels. Previous studies have indicated that alpha-synuclein (alpha-syn), a typical cytosolic protein, plays a significant role in the pathogenesis of Parkinson's disease (PD). It is also worth noting that the aggregated form of alpha-syn has the capacity to affect Ca2+ homeostasis by altering the function of Ca2+ regulation. The upregulation of leucine-rich repeat kinase 2 (LRRK2) is closely associated with PD pathogenesis. LRRK2 mutants exhibit a dysregulation of calcium signaling, resulting in dopaminergic neuronal degeneration. It could therefore be proposed that alpha-syn and LRRK2 play important roles in the mechanisms underlying Ca2+ dyshomeostasis and excitotoxicity in PD.