The Influence Of Chlorpytifos At Subthreshold Dose On The Cell Cycle Length Of Neural Precursor Cells Of The Mouse Embryonic Lateral Ventricle And The Expression Level Of Par3

Chlorpyrifos (CPF) is one kind of broad-spectrum pesticides. Many results were represented in the developmental neurotoxicity of subtoxic dosage chlorpyrifos exposure at animal prenatal and newborn stages. It was reported that CPF elicit morphological alternations in neural progenitors, which in turn change the thickness of the cerebral cortex and impair the cognitive and behavior functions even until adult. In this study, we focus on the progenitor developmental fate after CPF treatment. Cell cycle length of neural progenitors at embryo lateral ventricle and the related Par complex expression were investigated.Chapter two represented a classical assay to measure cell cycle length by labeling S-phase cells with Brdu insertion. There was a1.5h interval in each Brdu injection. The total procession includes10injections and the animals are sacrificed at0.5h after the last injection. Considering the multiply developmental stages of neural progenitors, this chapter only studied PVE cells at VZ and SVZ. The PVE cells were stratified into10Bins. The labeling index (LI) at each time point and each Bin was determined and the cell cycle length of these cells was calculated.Chapter three aimed to investigate the impacts of subtoxic CPF exposure on Par3expression level to VZ apical progenitors.0,1,5mg/kg of CPF treatment were take during E7.5-11.5, while embryo brain were obtained at El4, the peak of neurogenesis. Immunofluorescence staining of Par3expression was taken to determine the effects of subtoxic CPF prenatal exposure.Our result showed that different LI values of Bins exist in different time points between control and CPF groups. At early points, CPF exposure reduced the LI values in apical regions (Bin1-3). Along with the extension of tme points, CPF exposure gradually changes the LI values at basal VZ and SVZ regions (Bin10). Calculating the cell cycle length, we observed a total cycle length of16.89±0.22h in control and20.56h±0.28h in CPF, with S phase length of5.91±0.08h in control and6.58h±0.09h in CPF, G2+M phase length of2.09±0.08h in control and2.92±0.09h in CPF, G1phase length of8.89±0.06h in control and 11.06±0.28h in CPF.For Par polarity protein expression, it was found that5mg/kg of CPF prenatal treatment reduced the Par3immunofluorescence intension in El4apical VZ cells, while lmg/kg of CPF treatment had no obvious effects on the cells.In conclusion, our results showed that CPF prenatal exposure reduced the cell cycle length of VZ apical neural progenitors, especially for the G1phase length. Moreover, CPF treatment decreased the Par3expression in the same region.