[Effect of chlorpyrifos on autophagy-related protein expression in hippocampal neurons of SD rats].

Objective: To analyze the effect of chlorpyrifos on the expression of autophagy related proteins in rat hippocampal neurons, and to explore the role of autophagy in central nerve injury caused by acute chlorpyrifos poisoning. Methods: In October 2018, 35 male clean grade SD rats were randomly divided into 7 groups according to the observation time point, namely 0.5 d, 1 d, 2 d, 3 d, 5 d and 7 d groups and the control group, with 5 rats in each group. Each observation group was given 81.5 mg/kg chlorpyrifos by gavage, and the control group was given olive oil by gavage. The general conditions and poisoning symptoms of rats were observed continuously after exposure. The expressions of autophagy related proteins Beclin1, P62/SQSTM1 and LC3 in hippocampus were detected by Western blot. The cell morphology and LC3 expression in brain were observed by immunohistochemical staining. Results: Western blot results showed that compared with the control group, the expression of Beclin1 protein in hippocampal neurons of rats in the 1 d, 2 d, and 3 d groups increased, while the expression of P62/SQSTM1 protein in the 0.5 d, 1 d, and 2 d groups decreased, and the expression of LC3 protein was decreased in the 2 d group, and the differences were statistically significant (P<0.05) . The results of immunohistochemistry showed that the hippocampal neurons of rats in the 5 d group were arranged disorderly, and some nuclei contours disappeared, especially in the 7 d group. The LC3 protein was expressed in the cytoplasm, and the expression level gradually increased, reaching a peak on the second day. Conclusion: The early activation of autophagy in rats with acute chlorpyrifos poisoning may be involved in chlorpyrifos induced hippocampal neuronal injury.

[The expression of Nrf2 in the lung tissue of rats with acute diquat poisoning and the distribution of diquat in lungs].

Objective: To investigate the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) in the lung tissue of rats with acute diquat (DQ) poisoning and the distribution of diquat in lungs. Methods: Fifty-four fasted male Wistar rats were randomized into control group (n=6) and exposure group (n=48) . According to the time point, the exposure group was divided into 2 h, 4 h, 12 h, 1 d, 3 d, 7 d, 11 d and 14 d groups with 6 rats in each group. Exposure groups were administered 11.55 mg/kg DQ (1 ml/100 g BW) by single-dose of intragastric administration, while the control group rats were given normal saline. The histopathological changes of lung tissue of rats in each group were observed. The expression of nrf2 in lung tissue was detected by immunohistochemistry, and the diquat concentration in lungs was determined by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS) . Results: In the exposure group, DQ was detected in lungs on 2 hours after poisoning. The concentration of DQ in lung tissue decreased gradually over time, and there was no accumulation in lung tissue. The histopathological changes of lung tissue were not obvious in the early stage of poisoning. The injury was the most serious on the 3rd day, a large number of inflammatory cells could be seen in alveolar cavity and lung stroma, and the pathological injury of lung tissue began to be alleviated on the 7th day. The results of immunohistochemistry showed that Nrf2 was mainly expressed in the nucleus of pulmonery cells. The expression of Nrf2 in the exposure group was significantly higher than the control group. The expression of Nrf2 increased significantly at the 12th hour (P<0.05) , reached the peak on the 3rd day (P<0.05) . There was no difference between the control group and the 14th day (P>0.05) . Conclusion: There was no accumulation of DQ in the lung tissue for a long time, and there was a hysteresis in lung injury induced by redox reaction of DQ. Nrf2 was highly expressed in the lung tissue of rats with acute DQ poisoning, which was correlated with histopathology injury of lung tissue, suggesting that Nrf2 plays an important role in antagonizing acute lung injury induced by DQ.