FYN and Hyperglycemia: In this study, we found that HG treatment activated Fyn, characterized by elevated levels of p-Y416 both in vitro and in vivo, while the proapoptotic effect of HG was abolished by the Fyn inhibitor PP1 in vitro, suggesting that Fyn activity plays a crucial role in HG-induced dopaminergic neuronal apoptotic death and may be involved in dopaminergic neuron loss in PD patients with hyperglycemia.