| Individuals continuously confronted with various stresses in modern life generate high levels of cortisol(corticosterone in rodents),the major glucocorticoid secreted by adrenal gland when hypothalamic-pituitary-adrenal axis is activated.Chronic stress can induce constant release of glucocorticoid and cause many serious health problems,such as mental disorders,cardiovascular diseases and autoimmune diseases.Many staudies have suggested that the neurotoxic effect of corticosterone is mediated through increased oxidative stress and apoptosis.Although SIRT1 has been shown to be protective against conditions such as DNA damage and oxidative stress through autophagy regulation,the exact role of SIRT1 and autophagy in corticosterone-induced cellular stress is still unclear.In this study,ventral spinal cord 4.1 motoneurons were treated with different concentrations of corticosterone for different time.Cell viability was assessed by CCK-8 assay to determine the optimal condition for the establishment of the cellular stress model.Then,the expression level of SIRT1 was regulated by transfection of either overexpression or knockdown plasmid.In the meanwhile,western blot and RT-qPCR were employed to detect cellular autophagic flux after corticosterone treatment in order to figure out how SIRT1 regulates autophagy under cellular stress.We also utilized TUNEL staining to evaluate apoptosis rate in SIRT1 overexpressing cells after corticosterone treatment,so that we can understand how SIRT1 affects apoptosis under cellular stress.Our study found that there was a dose-dependent decrease in SIRT1 expression and cell viability,and a raise in LC3B II/I ratio with increasing concentrations of corticosterone.Overexpression of SIRT1 inhibited corticosterone-induced autophagy and enhanced cell apoptosis,whereas suppressing SIRT1 promoted autophagy level.These findings might help us better understand the role of SIRT1 and autophagy activation in chronic stress. |
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