A Study On Sensitivity Of Dieldrin Toxicity On Human Dopaminergic SH-SY5Y Cells At Different Stages Of Differentiation

BackgroundDieldrin belongs to organochlorines and was developed in the middle of the last century,it may produce neurotoxicty through a variety of exposure routes. In vivo and vitro studies suggest that dopaminergic systems are particularly sensitive to dieldrin. Brain tissue test results of Parkinson's patients also suggest that there may be etiologic relationship between dieldrin and Parkinson's disease. SH-SY5Y cells line derived from neuroblastoma of children;They can express a variety of markers of dopaminergic(such as TH and DAT). They often were used as a model of dopaminergic neurons to study the pathogenesis of Parkinson's disease. In the experimental study, we often use a variety of differentiation factors(such as RA or TPA) to induce differentiation of SH-SY5Y cells and to show characteristics of dopaminergic neurons;however , There are a lot of sduties using undifferentiated SH-SY5Y cells directly. At present,there is still controversial of the undifferentiated and differentiated SH-SY5Y human dopaminergic cells in the sensitivity of nerve poison.ObjectiveUsing SH-SY5Y cells as human dopaminergic neurons culture model, inducing cell differentiation by RA, To compare the cytotoxicity of dieldrin on dopaminergic neurons at different developmental stages; On this basis, explore the effect of dieldrin on the SH-SY5Y cell differentiation,To investigate the impact of dieldrin to the key neurological development stage. MethodsUsing SH-SY5Y cells as human dopaminergic neurons culture model, the cells were seeded at a density of 1×10~4 /well and 5×10~3 /well in 96-well plates.All-trans-retinoic acid(10μM) induced differentiation of SH-SY5Y cells. 1,3,10,30,100μM of dieldrin exposured on the cells for 24 hours.MTT and Live/Dead viability/cytotoxicity kit were used to assay the cytotoxicity of dieldrin on the undifferentiated (0 d),differentiating (4 d) or differentiated (7 d) SH-SY5Y cells. Using Coomassie brilliant blue staining, calculate cells differentiation rates after exposured to1,3μM of dieldrin for 24h at differentiation medium.Statistical treatmentAll results wre expressed as (x|-)±s.The data was analyzed with SPSS 13.0. Test of variance homogeneity and One Way ANOVA were used in comparison among groups. Further pairwise compared between groups: if variance was homogeneity,we used Student-Newman-Keuls; if variance was missing, we used Games-Howell. Chi-square test was used to compare between rates. Non-parametric Spearman correlation analysis was used in Correlation analysis of the factors. P <0.05 was considered statistically significant.ResultsThe results of MTT showed that cells viability was decreased by dieldrin in a dose depended manner; The differentiating SH-SY5Y cells were most sensitive to dieldrin. Cells exposured to dieldrin at concentrations of 10-100μM were induced dose-dependent cell death. The differentiating/differentiated SH-SY5Y cells were more sensitive to dieldrin than the undifferentiated cells; and the differentiating SH-SY5Y cells were more sensitive than the differentiated cells. The results of Coomassie brilliant blue staining showed that 3μM dieldrin can significantly influence the differentiating (4 d) SH-SY5Y cells'differentiation. ConclusionsThe differentiating cells were most sensitive to dieldrin toxicity;Dieldrin can inhibit the differentiation of dopaminergic neurons as well.These results suggest that dieldrin exposure may influence the key parts such as survival and differentiation of neurons and produce developmental neurontoxicity.