Inhibition of α-Synuclein Accumulation Improves Neuronal Apoptosis and Delayed Postoperative Cognitive Recovery in Aged Mice

Delayed neurocognitive recovery (dNCR) is a major complication after anesthesia and surgery in older adults. Alpha-synuclein (α-syn; encoded by the gene, SNCA) has recently been shown to play an important role in hippocampus-dependent working memory. Aggregated forms of α-syn are associated with multiple neurotoxic mechanisms, such as mitochondrial dysfunction and cell death. In this study, we found that blocking α-syn improved both mitochondrial function and mitochondria-dependent neuronal apoptosis in a mouse model of dNCR. Various forms of α-syn (including total α-syn, phosphorylated-Ser129-α-syn, and oligomers) were upregulated in hippocampal tissue and extracted mitochondria after surgical challenge. Clenbuterol is a novel transcription modulator of Scna. Clenbuterol significantly attenuated surgery-induced progressive accumulation of various toxic α-syn forms in the hippocampus, as well as mitochondrial damage and memory deficits in aged mice following surgery. We also observed excessive mitochondrial α-syn accumulation and increased mitochondria-mediated apoptosis in vitro using nerve growth factor-differentiated PC12 cells and primary hippocampal neurons exposed to lipopolysaccharide. To further validate the neuroprotective effect of α-syn inhibition, we used a lentiviral Snca-shRNA (Lv-shSnca) to knockdown Snca. Of note, Lv-shSnca transfection significantly inhibited neuronal apoptosis mediated by the mitochondrial apoptosis pathway in neurons exposed to lipopolysaccharide. This α-syn inhibition improved the disruption to mitochondrial morphology and function, as well as decreased levels of apoptosis. Our results suggest that targeting pathological α-syn may achieve neuroprotection through regulation of mitochondrial homeostasis and suppression of apoptosis in the aged hippocampus, further strengthening the therapeutic potential of targeting α-syn for dNCR.