Effects Of Prenatal Exposure Of Three Organophosphorus Pesticides On Neurodevelopmental Brain Structure

More and more attention has been taken in developmental neurotoxicity with the widespread use of organophosphate pesticides, in addition to acute toxicity. As cell multiplication and differentiation connected with cell division, it is interesting to investigate developmental neurotoxicity of organophosphorus pesticides in the division process. This article assesses the morphological changes in brain tissues elicited by three organophosphorus pesticides, diazinon (DZN), chlorpyrifos (CPF) and acephate (ACP).E7.5～E11.5 (Embryal days) of pregnant mices, which is in the neural tube formation stage, were injected subcutaneously (sc) 2mg/kg of DZN, 2mg/kg of CPF and 50mg/kg of ACP for consecutive 5 days. Same volume of dimethyl sulfoxide was injected in control groups. Fresh brain tissues were isolated from PND1～4 (postnatal days) and E16 mouse, embreded in paraffin and cutted into slices. Morphology of the slices was measured under microscopy, including cell categories and number in cortex S1, hippocampus CA1 and CA3, and mitotic plane angle of neural progenitors in ventricular zone (VZ).The experimental results show that, after DZN, CPF and ACP exposure in early pregnancy, there is no significant change of neuron number in the cortex S1, but glial cell number decreases after DZN and CPF treatment. Pyramidal cells in hippocampus CA1 and CA3 were found significantly reduced after DZN and CPF treatment, with no significant change in ACP group. The cell volume density of hippocampus decreases after DZN and CPF treatment. In measurement of mitotic plane orientation in VZ surface cells, we discovered most of plane angle are vertical, with a small amount of plane angle are oblique and horizontal. After DZN and CPF treatment, ratio of the vertical division decreases with an increased ratio of the horizontal and oblique division. There is no significance change in ACP group. The total mitotic cell ratio in VZ surface has no significant change in the all three groups.These results suggest that DZN, CPF treatment in early pregnancy elicit minor changes in developmental brain tissues, and change the mitotic plane orientation in neural progenitors of VZ surface cells.