The Studies On The Mechanism Of Sub-Chronic Manganism To The Immune System Of Cock

Manganese(Mn) is widely used in industrial and agricultural production, such as dry batteries, metal pencils, sterilizing agents and chemical fertilizer.However, it results in severve pollution to environment and also severve damages to human and animals,causing enormous economic losses.So far,the researches on toxicity of Mn focus on nervous and genital systems, while the reports on immune system were seldom, even of poultry.This experiment took sp!een,thymus and bursa of Fabricius as target organs, reproduced the deuto-chronic manganism models of Hailan cocks by feeding with excess Mn (low-dosed group 600 mg/kg;middle-dosed group 900 mg/kg; high-dosed group 1800 mg/kg) ,and on 30d,60d,90d after treatment,the histopathology changes, oxidative damages, apoptosis,DNA damages,the contents of cytokine and microelements were detected.The results showed as followed:1 Manganism could induce microstructure and ultrastructure changes of immune organs,which were the bases of manganism on immuno suppression.2 In the chicks of manganism ,the mRNA expressions of IL-1βand IL-2 in spleen, thymus and bursa of Fabricius decreased,the content of IL-1βand IL-2 serum decreased, it was proved that manganism induced immuno suppression in molecular level.3 In the chicks of manganism, the contents of Mn in spleen, thymus and bursa of Fabricius increased, the contents of Fe, Zn and Ca decreased, it was shown that manganism induced the unbalance of the contents of the trace elements in immune organs, and then suppressed the immune functions.4 Manganism could induce oxidative stress in immune organs of the chicks ,and then the activity of GSH-Px,SOD and the capability of anti-OH·decreased;the contents of MDA and protein carbonyl increased, causing protein oxidation damages.5 By the detection,it was discovered that manganism could indcuce DNA single-strand break and DNA-protein cross link in lymphocytes of spleen, thymus and bursa of Fabricius, showing time and dosage effect, which was one of the mechanism of manganism on immuno suppression.6 Manganism could induce lymphocyte apoptosis in spleen,thymus and bursa of Fabricius, which could cause immuno suppression.It was concluded that manganism can change the morphostructure of immune organs and decrease the functions of immune system.Overdose manganese could induce oxidative stress, DNA damage, apoptosis and the unbalance of trace elements, which were one of the mechanism of manganism on immuno suppression.