Dexmedetomidine Protects SH-SY5Y Cells Against MPP~+-induced Declining Of Mitochondrial Membrane Potential And Cell Cycle Deficits

Parkinson’s disease(PD)is a common neurodegenerative disease,Deep brain stimulation(DBS)implantation can reduce the motor and non-motor symptoms of Parkinson’s disease.Intraoperative anxiety,pain,and fear can cause patient restlessness,movement and poor hemodynamics.Cooperative patient microelectrode recording(MER)and stimulation positioning process are more accurate.Therefore,during DBS placement,sedation is necessary,and the commonly used sedative is Dexmedetomidine(Dex).Dex is an adrenal alpha 2 receptor activator,which can meet the needs of DBS surgery without respiratory depression common to other sedatives,and studies have suggested that Dex plays a neuroprotective role in brain injury models.However,there is also evidence that the use of anesthetics may accelerate the progression of neurodegenerative diseases.In this study,we cultured the all-trans-retinoicacid(ATRA)differentiated SH-SY5Y cells in vitro and then treated with MPP~+(1.5m M)with or without Dex(10n M)or Dex combined with Atipamezole(Ati,100n M,adrenergicα2 receptor inhibitor).Analyze the proportion of apoptotic cells,mitochondrial membrane potential(Δψm),reactive oxygen species(ROS),and apoptotic protein markers(caspase-3,9)by flow cytometry and immunofluorescence to observe the oxidative stress of Dex on the Parkinson’s cell model and the impact of apoptosis.By observing the cell cycle and cell cycle-related proteins(p27 KIP1,cyclin D1,cdk4,cyclin E1,cdk2,cyclin A2,cyclin B1)changes to further explore possible mechanisms.The results as follows:1.After SH-SY5Y cells differentiates by ATRA,cells had more mature neuronal expression morphology.0.5-3m M MPP~+reduces cell viability in a dose-dependent.The cell viability at 1.5m M MPP~+is54.99±3.76%,which is the most suitable concentration for modeling.Different concentrations of Dex(1-1000n M)can improve the cell viability of the PD model after pretreatment.2.Dex pretreatment suppressed the apoptosis of SH-SY5Y cells induced by MPP~+.Hoechst 33258 staining showed that MPP~+increased the proportion of cells with nucleus condensation,and Dex suppressed the damage of nuclear morphology caused by MPP~+.Flow cytometry showed that Dex inhibited the percentage of SH-SY5Y apoptotic cells induced by MPP~+.The results of immunofluorescence and western blotting showed that Dex pretreatment reduced the expression of apoptotic proteins Cleave-caspase 3 and 9.3.Flow cytometry and immunofluorescence examination showed that MPP~+reduced the cellΔψm and caused excessive ROS production.Dex improves the intracellularΔψm induced by MPP~+and reduces the accumulation of ROS.4.MPP~+activates the cell cycle,allowing the cell to enter the S phase through the G1/S checkpoint.Dex exerts a neuroprotective effect by increased cells in G1 phase,reducing cells in S phase,inhibiting cell cycle activation and reducing G1/S transition in the cell cycle.5.MPP~+increased the expression of cyclin D1,cyclin E1,cdk2,cyclin A2 and DK4 in SH-SY5Y cells,and decreased p27 KIP1,but cyclin B did not change.Dex pretreatment can reduce the expression of cyclin D1,cdk4,cyclin E1,cdk2 and cyclin A2 induced by MPP+,and increase the expression of p27 KIP1.Conclusion:Dex reduce the apoptosis of SH-SY5Y cells induced by MPP~+by preventing the loss ofΔψm,reducing the generation of ROS,and regulating the cell cycle.Dex may be a potential drug for the treatment of PD...