Effect of L-carnitine on apoptosis in Schwann cells induced by high glucose

Objective To investigate the effect of L-carnitine on the apoptosis in Schwann cells induced by high glucose.Methods The cell line RSC96 cultured in vitro were seeded in 96-well plates at a density of 1.5 × 104/ml (200 μl/well) or in 6-well plates at a density of 2 × 105/ml (2 ml/well) and cultured for 24 h.The cells were randomly divided into 4 groups (n =24 each) using a random number table:normal control group (group C),high glucose group (group H),high glucose + L-carnitine group (group H + L),and mannitol osmotic control group (group M).The cells in group C were incubated in the plain culture medium containing normal glucose (5.6 mmol/L).The cells were incubated in the medium containing glucose 50 mmol/L in group H or in the medium containing glucose 50 mmol/L and L-carnitine 50 μmol/L (final concentration) in group H + L.The cells were incubated in the medium containing normal glucose (5.6 mtmol/L) and mannitol 44.4 mmol/L in group M.At 48 h of incubation,cell growth conditions were observed under inverted microscope,superoxide dismutase (SOD) activity was measured by xanthine oxidase method,malondialdehyde (MDA) content was measured by thiobarbituric acid test,cell viability was measured by MTT assay and cell apoptosis was measured by flow cytometry.The expression of activated caspase-3 and poly (ADP-ribose) polymerase-1 (PARP-1) protein was detected by Western blot.Results Compared with group C,the cell viability and SOD activity were significantly decreased,MDA content and apoptotic rate were increased,and the expression of activated caspase-3 and PARP-1 protein was up-regulated in H and H + L groups,and no significant changes were found in group M.Compared with group H,the cell viability and SOD activity were significantly increased,MDA content and apoptotic rate were decreased,and the expression of activated caspase-3 and PARP-1 protein was down-regulated in group H + L.Conclusion L-camitine can attenuate high glucose-induced apoptosis in Schwann cells by inhibiting oxidative stress responses and down-regulating the expression of activated caspase-3 and PARP-1. Key words: Carnitine ;  Diabetic neuropathies;  Apoptosis