摘要：Emerging evidence implicates α-synuclein oligomers as potential culprits in the pathogenesis of Lewy body disease (LBD). Soluble oligomeric α-synuclein accumulation in cytoplasm is believed to modify neuronal activities and intraneural Ca 2+ dynamics, which augment the metabolic burden in central neurons vulnerable to LBD, although this hypothesis remains to be fully tested. We evaluated how intracellular α-synuclein oligomers affect the neuronal excitabilities and Ca 2+ dynamics of pyramidal neurons in neocortical slices from mice. Intracellular application of α-synuclein containing stable higher-order oligomers (αSNo) significantly reduced spike frequency during current injection, elongated the duration of spike afterhyperpolarization (AHP), and enlarged AHP current charge in comparison with that of α-synuclein without higher-order oligomers. This αSNo-mediated alteration was triggered by spike-induced Ca 2+ release from inositol trisphosphate receptors (IP 3 R) functionally coupled with L-type Ca 2+ channels and SK-type K + channels. Further electrophysiological and immunochemical observations revealed that α-synuclein oligomers greater than 100 kDa were directly associated with calcium-binding protein 1, which is responsible for regulating IP 3 R gating. They also block Ca 2+ -dependent inactivation of IP 3 R, and trigger Ca 2+ -induced Ca 2+ release from IP 3 R during multiple spikes. This aberrant machinery may result in intraneural Ca 2+ dyshomeostasis and may be the molecular basis for the vulnerability of neurons in LBD brains.
