Effects Of Arsenic Trioxide On The Methionine Sulfoxide Reductases And Apoptosis In Chicken Primary Hepatocytes

Arsenic is widespread in water,soil,and air with the increasing of wastewater discharge of industry,agriculture and its application in animal production.Long term arsenic exposure not only induce chronic toxicity in animal,but also cause huge economic losses to livestock production.Many studies have shown that arseniasis is associated with oxidative damage,but the relationship between arseniasis and methionine sulfoxide reductase was not reported now.In order to study the relationship between arsenic trioxide（ATO）,oxidative damage,and Msrs in chicken primary hepatocytes,We treated chicken primary hepatocytes with different concentrations of arsenic,to reveal the effects of arsenic on chicken primary hepatocytes Msrs and possible mechanisms from cell proliferation,apoptosis,Msrs transcription,and protein levels.Primary hepatocytes were randomly divided into the control group（0μM ATO）,low-dose group（0.6μM ATO）,medium-dose groups（1.2μM ATO,2.4μM ATO）,high-dose group（4.8μM ATO）,N-acetylcysteine group（1.0 mM NAC）and ATO with NAC group after cultured for 36 h and then continued to culture for 24 h.We examined cell cycle,apoptosis and the expression of Msr.（1）The result showed that ATO could enhance hepatocytes proliferation and cell viability at the low dose and suppress hepatocytes proliferation and cell viability at the high doses,and NAC reversed the effect of high dose ATO.（2）Along with the increasing dosage of ATO,the content of malondialdehyde（MDA）and glutathione（GSH）increased dramatically（P<0.05）,the content of active oxygen（ROS）and the enzymatic activity of catalase（CAT）increased dramatically in high-dose group（P<0.05）,the activity of superoxide dismutase（SOD）increased to a peak then decreased.The content of GSH and the activity of SOD increased significantly,and the content of CAT and MDA decreased obviously in ATO with NAC group compared with high-dose group（P<0.05）.（3）We found that mRNA expression of Bak1 up-regulated significantly in medium and high-dose group,the Bax did not change,while the mRNA expression of p53 and Bcl-2down-regulated significantly in high-dose group,and the p53 up-regulated significantly in medium group.The apoptosis rate of hepatocytes increased significantly in high-dose group（P<0.01）.（4）We found that mRNA expression of MsrA decreased significantly in high-dose group and ATO with NAC group,the MsrB₁ decreased significantly except NAC group and low-dose group,the MsrB₃ decreased significantly except NAC group.The protein expression of MsrA and MsrB₁ increased significantly as the increasing of ATO in all groups（P<0.05）,but it decreased significantly in ATO with NAC group compared with high-dose group（P<0.01）.Conclusion:As mentioned above it is suggested that ATO could enhance chicken primary hepatocytes proliferation at the low dose,and it would cause oxidative injuries,which would eventually lead to apoptosis at the high doses.At the same time,the mRNA expression of Msrs were reduced and the protein expression of Msrs were ascend.It suggested that Msrs may play an important role in oxidative damage restoration caused by ATO in hepatocytes.