The Protective Effect Of L-carnitine On Injury In Schwann Cells Induced By High Glucose And The Possible Mechanism

Objective: L-carnitine(LC)can be used for the treatment of diabetic peripheral neuropathy(DPN), but whether its mechanism have the relation with inhibiting injury in schwann cell induced by high glucose remains to be researched. In this research, we established injury model of the RSC96 induced by high glucose, and investigate the effect of L-carnitine on the injury in rat Schwann cells induced by high glucose and its possible mechanism. Then we can provide new theoretical references for its application in DPN.Methods: Cultured rat schwann cells(RSC96) were seeded in 96-well plates with a density of 1.5×104/ml(200μl/well) or in 6-well plates(2ml/well) with a density of 2×105/ml. 1.Used the concentrations of 25mmol/L、50mmol/L、100mmol/L glucose to stimulate the RSC96. Cell proliferation activity was detected by MTT, and choosed the suitable concentration of glucose to establish cell damage model according to the results. Then the cells were given the concentration of 10μmol/L、25μmol/L、50μmol/L、75μmol/L、100μmol/L L-carnitine and measure cell activity after 48 h,and choosed the best concentration. in order to remove the effect to the results of mannitol induced by high glucose, we set up group mannitol as experimental control. 2.According to the first Part of the experiment, we choosed 50mmol/L glucose and 50μmol/L L-carnitine for this Part. RSC96 were randomly divided into five groups(N=5): group normally cultured cells(groupC), group high glucose(group H), group high glucose with L-carnitine(group H+L), group L-carnitine alone(group L), group mannitol(group M). Then cultured for 48 h:Cell growth conditions were observed under inverted microscope and photographed, The SOD activity and MDA content were measured.The cell apoptosis rate was measured.The expression of activated Caspase-3 and activated PARP-1 protein in cells were detected by Western blot method.Results: 1.MTT results showed that cell growth activity was restrained significantly after glucose stimulation, and was dose dependently(P<0.05).As 50mmol/L glucose can induce cell growth activity be decreased to 58% of group C, cell activity was decreased significantly compared with group C.we chose 50mmol/L glucose as the subsequent dose. No significant difference in the indicators was found in group L and M compared with group C(P > 0.05). But LC could significantly improve the activity in the RSC96 stimulated by glucose(P < 0.05). And the 50μmol/L LC was the most effective. 2.Compared with group C, the quantity of adherent cells decreased and suspension cells increased, the SOD activity was significantly decreased, MDA content, the apoptotic rate and the expression of activated Caspase-3 protein fragment fragment and PARP-1 protein fragment were significantly increased in group H and group H+L(P<0.05),No significant difference was found in group L and group M(P>0.05). Compared with group H, the quantity of adherent cells increased and suspension cells decreased, the SOD activity was significantly increased, MDA content, the apoptotic rate and the expression of activated Caspase-3 protein fragment and activated PARP-1 protein fragment were decreased significantly in the group H+L(P<0.05).Conclusion:High glucose can induce injury in RSC96, It maybe related with elevating the level of oxidative stress, while irrelated with mannitol. L-carnitine can effectively attenuate high glucose-induced injury to rat schwann cells by inhibitting oxidative stress, down-regulating expression of activated Caspase-3 protein and activated PARP-1 protein fragment, and decreasing the apoptosis rate.