Effects of AMPA receptor regulatory protein on the apoptosis of oligodendrocyte precursor cells under hypoxia and hypoglycemia conditions
Objective: To observe the variation of glutamate(AMPA) receptor interacting protein(GRIPs)and apoptosis of oligodendrocyte precursor cells (OPCs)under oxygen glucose deprivation (OGD) condition, so as to explore the role of GRIPs in AMPA receptor-induced excitotoxic injury. Methods: OPCs were divided into control group, 60 min OGD group and 120 min OGD group.Real-time polymerase chain reaction (PCR) and Western blot were used to detect the mRNA and protein expressions of GRIP1 and GRIP2 under OGD conditions. OPCs were divided into blank control group, OPCs+ OGD group, OPCs+ cyclic adenosine monophosphate(cAMP)+ OGD group, OPCs+ cAMP+ OGD+ GRIP1 small interfering RNA(siRNA) group, OPCs+ cAMP+ OGD+ GRIP1 siRNA negative control group, OPCs+ cAMP+ OGD+ GRIP2 siRNA group, OPCs+ cAMP+ OGD+ GRIP2 siRNA negative control group again, and terminal-deoxynucleoitidyl transferase mediated nick end labeling(TUNEL) kit was used to detect the apoptosis of each group.Fluo-4 fluorescent probe was used to measure the changes of intracellular free calcium. Results: OGD caused damage to OPCs, and the light microscope showed that the cell contour was not clear and the cell body retracts. The expressions of GRIP1 (1.233±0.060 vs.1.003±0.079, P<0.05) and GRIP2 (1.396±0.069 vs.1.001±0.037, P<0.05) were significantly higher than those in control group after 60 min of OGD was, and the longer the period of OGD, the higher the expression levels of GRIP1 (1.416±0.064 vs.1.233±0.060, P<0.01) and GRIP2 (1.680±0.018 vs.1.396±0.069, P<0.01) were. When GRIP1 and GRIP2 were down-regulated, the level of intracellular free calcium ion decreased(0.054±0.003 vs.0.074±0.003, P<0.01; 0.060±0.003 vs. 0.074±0.003, P<0.01), and the apoptosis rate decreased as well [(20.703±3.882)% vs.(11.470±1.679)%, P<0.05; (19.070±1.106)% vs.(14.448±0.849)%, P<0.01]. Conclusions: GRIP1 and GRIP2 are involved in the damage of OPCs that are caused by OGD, which may trigger AMPA receptor-mediated excitotoxicity by regulating Ca2+ permeability.
