Effects Of Excessive Iron On Oxidation-antioxidation Function In Immune Organs Of Sheep

Iron is an essential trace element in the process of life activities,which has important physiological functions.In actual production,the iron intake of sheep often exceeds the maximum tolerance?500 mg/kg?recommended by NRC.Excessive iron will cause immune stress,lead to immune dysfunction and harm the development of animal husbandry.In this experiment,the sheep were randomly divided into four groups:control group,iron excess group 1,iron excess group 2and iron excess group 3.The four groups were fed with basal diets supplemented with 50,500,1000,and 1500 mg Fe/kg as ferrous sulfate monohydrate respectively.The immune organs?spleen,thymus,palatine tonsil,portal lymph nodes and mesenteric lymph nodes?of sheep were collected after 75 days.The contents of iron,MDA,NO,H₂O₂,the activities of i NOS and GPx,and the level of T-AOC were measured by hemistry colorimetric method.The contents of hepcidin and i NOS were tested by indirect ELISA.The expression of hepcidin,i NOS and GPx1 m RNA in immune organs was detected by q PCR,and Western Blot was used to examine GPx1 protein expression.Histopathological changes and hemosiderin deposition were observed using by paraffin section,HE and Prussian blue staining techniques.The purpose of this study was to explore the effect of excessive iron on oxidation-antioxidation function of sheep.The main results are as follows:?1?After feeding with excessive iron,MDA,NO contents and i NOS activity of immune organs in sheep increased,while H₂O₂ content decreased.The i NOS content and m RNA expression in immune organs of sheep were significantly lower than those of control group?P<0.05 or P<0.01?.After adding 1500 mg Fe/kg to the basal diets,NO content and i NOS activity in immune organs were significantly higher than those of control sheep?P<0.05 or P<0.01?.The results showed that feeding with excessive iron could enhance the lipid peroxidation of immune organs,increase oxidants contents,and make the body in a state of oxidative stress.?2?The T-AOC level and GPx activity in immune organs of sheep decreased after feeding with excessive iron,while GPx1 m RNA expression was extremely significant higher than that of control group?P<0.01?.The T-AOC level in the iron excess group was significantly lower than that of control group?P<0.05 or P<0.01?.The GPx activity of spleen,palatine tonsil and mesenteric lymph nodes in sheep was extremely significant lower than that of control sheep?P<0.01?.The GPx1 protein expression of s portal lymph nodes in sheep was extremely significant higher than that of control group?P<0.01?.The results showed that feeding with excessive iron could significantly decline the antioxidant enzymes activities,antioxidants contents and antioxidant function of immune organs in sheep.?3?Hepcidin content and m RNA expression in the immune organs of sheep fed with excessive iron was significantly higher than those of control group?P<0.05 or P<0.01?,and there were significant differences among three iron excess groups.The results showed that feeding with excessive iron could increase hepcidin expression,and hepcidin played a role of iron homeostasis regulation.?4?After feeding with excessive iron,the iron content in immune organs increased,in which the iron content in spleen was the highest and that in palatine tonsil was the least.The degree of histopathological damage increased with the increase of iron intake,such as lymphocyte infiltration and cell death,indicating that excessive iron can cause immune organs damage in sheep.