Tetramethylpyrazine Analogue CXC195 Protects Against Dopaminergic Neuronal Apoptosis In 6-OHDA-Induced Parkinson’s Disease Mice

Parkinson’s disease(PD)is a progressive neurodegenerative disorder and characterized by motor system disorders resulting in loss of dopaminergic(DA)neurons.CXC195,a novel tetramethylpyrazine derivative,has been shown strongest neuroprotective effects due to its anti-apoptotic activity.However,whether CXC195 protects against DA neuronal damage in PD and the mechanisms underlying its beneficial effects are unknown.The purpose of the study was to investigate the potential neuroprotective role of CXC195 and to elucidate its mechanism of action against 6-hydroxydopamine(6-OHDA)-induced mouse model of PD.C57BL/6 mice were placed in a stereotaxic device and given 6-OHDA or saline alone into two different sites of the striatum separately.Mice were given CXC195 by daily intraperitoneal injection for 7 days or 14 days after 6-OHDA.Wortmannin.the specific PI3K inhibitor,was injected via the tail vein I hour before 6-OHDA injection to block the PI3K/Akt/GSK3β pathway.The degree of dopaminergic dysfunction and deterioration of motor performance were evaluated by the apomorphine-induced rotation test.The protein levels of TH in substantia nigra(SN)and striatum(STR)were assessed by western blot and immunohistochemistry.The levels of DA in striatum were measured by LC/MS.Western blot is performed to detect the phosphorylation of Akt at Ser 473 and GSK3(3 at Ser 9,and the protein levels of caspase-3,Bax and Bcl-2 involved in apoptotic signaling pathways.TUNEL staining is used to assess the apoptosis in SN.CXC195 administration improved the motor function recovery and increased the TH-positive neurons survival in PD mice.Our further findings confirmed treatment of CXC195 at the dose of 10 mg/kg significantly inhibited the apoptosis by decreasing the level of cleaved caspase-3 and Bax,and increasing the level of Bcl-2 in 6-OHDA-lesioned mice.Meanwhile,6-OHDA also decreased the amount of phosphorylated Akt while increased GSK-3P activity(the amount of phosphorylated GSK-3β at Ser 9 was decreased)which was prevented by CXC195.Wortmannin,a specific PI3K inhibitor,dramatically abolished the changes induced by CXC195.Our study firstly demonstrated that CXC195 protected against DA neurodegeneration in 6-OHDA-induced PD model by its anti-apoptotic properties and PI3K/Akt/GSK3βsignaling pathway was involved in it.