Studies On Dimethoate-induced Oxidative Stress And Hepatocytes Apoptosis In Rats' Liver

The present study was carried out to investigate the effects and mechanisms of dimethoate-induced oxidative stress and hepatocytes apoptosis in rats'liver, the histopathology and ultramicrostructure changes, anti-oxidative enzymes and lipid peroxidation were detected to determine the role of dimethoate in production oxidative stress in rats'liver. At the same time, the general toxicity and apoptosis effects of dimethoate were researched via primary cultured hepatocytes in vitro. Apoptotic rate was detected by Annexin-V/PI double staining, intracellular ROS, mitochondrial membrane potential and concentration were detected with DCFH-DA, Rodamin 123 and Fluo-2-AM respectively. The mechanism of these factors in dimethoate-induced aoptosis in hepatocytes were disccused in this paper too.The results showed that the activity of AChE were both decresed in plasma and liver of experimental rats exposured with 0, 1, 6 and 30mg/kg b.w. dimethoate for 30d respectively, but no obvious clinical symptoms were observed. It could be presumed that the occurrence of clinical symptoms was not only related with the degree of AChE reduction, but mainly with the speed of reduction. The activity of SOD were increased in all treated group accompanied with GSH-Px and CAT decreased in low group but increased in high group. MDA concentration were increased 29%,69% and 129% in treated groups when compared with control group respectivity. Histopathology and ultramicrostructure survey showed congestion of hepatic lobules, fatty degenerationthe, shrinkage, split and apoptotic body of the nucleus. The results showed that subchronic esposure of dimethoate for 30d not only induced oxidative stress, but also cause liver damage in experimental rats.The results of in vitro test showed that exposured with dimethoate of 0, 3, 30, 300μmol/L for 12h and 24h could inhibited hepatocytes proliferation at different degree, and present time-dose effects. The survival rate of hepatocytes were 85, 72 and 67% at 48h in treated groups and aggregate with the prolongation of time. Increase of LDH activity were observed in all treated groups which concentration were 7.35 and 8.75 times in medium supernant when compared with control groups in 300μmol/L group at 12h and 24h respectively (P<0.01). Decrease of GSH concentration were decreased in all treated groups and significant in 30 and 300μmol/L groups. Hepatocytes apoptotic rates were increased significantly from 3.1% in control group to 16.9% in 300μmol/L group by flow cytometry detection use Annexin V/PI staining. Intracellular ROS level were increased in 3μmol/L to 100μmol/L group and slightly subside in 300μmol/L group. Decreased of mitochondria membrane potential owing to permeability transition was observed in our study too except in 300μmol/L group at 24h. Intracellular Ca2+ concentration were increased in all group and reached highest peak in 3μmol/L group, diffirent was significant(P<0.01). All indicated that dimethoate-induced apoptosis was related with generation of ROS and damage of hepatocytes membrane.