The Effects Of Cadmium-Aligned Fissure Spline Immune Function Of Schizothorax Prenantiand The Intervention Of Nanoselium(SeNPs)

This study investigated the effects of different levels of nano selenium（SeNPs）on antioxidant and immune function and expression of immune-related genes in Schizothorax prenanti exposed to cadmium in basal diet.The Schizothorax prenanti with an average weight of 96±8.54g/tail were randomly divided into 5 treatment groups,namely control（C）group,control+Cd group and low,medium and high dose SeNPs group（0.2,0.4,0.8mg/kg）.Each treatment group had 3 replicates and each repeat had 20 tails.After continuous feeding for 63d（42d+21d）,the growth indexes,serum antioxidant and immune indexes,and the relative expression levels of immune-related genes in the midgut,liver,head and kidney,and spleen of the Schizothorax prenanti were measured after 42d feeding.At 43d,the C+Cd group and the low,medium and high SeNPs groups were exposed to cadmium with a cadmium solution of 0.1mg/L Cd²⁺for a period of 21 days.The antioxidant and immune indexes in the serum of the Schizothorax prenanti were measured at 1,7,14 and 21days of cadmium exposure.The contents of cadmium and selenium in the midgut,liver and muscle and the relative expression levels of immune-related genes in the midgut,liver,head and kidney,and spleen tissues were also measured at 21d of cadmium exposure.The results show that:1.When fed for 42d,（1）SeNPs0.2 and SeNPs0.4 groups had a significant increase in fatness,the relative growth rate and specific growth rate of each SeNPs dose group were significantly increased,and the fat in SeNPs0.4 group was significantly increased.（2）serum activities of superoxide dismutase（SOD）and glutathione peroxidase（GSH-Px）and glutathione s-s transferase（GSH-ST）were significantly increased in SeNPs0.2 and SeNPs0.4 groups,while malondialdehyde（MDA）in SeNPs0.2 and SeNPs0.4 groups were significantly reduced.（3）serum levels of immunoglobulin M（Ig M）and complement bypass hemolysis activity（ACH50）were significantly increased in the SeNPs0.2 and SeNPs0.4 groups,and the activity of serum intermediate-acid phosphatase（ACP）was significantly increased in the SeNPs0.2 and SeNPs0.4 groups,while the contents of nitric oxide（NO）and inducible nitric oxide synthase（i NOS）in the SeNPs0.4 group were significantly increased in the SeNPs groups.The expression levels of pro-inflammatory factors（TNF-α,IL-1β）in the midgut and head kidney of Schizothorax prenanti in each SeNPs group were significantly up-regulated,and the expression levels of anti-inflammatory factors in the midgut,spleen and head kidney（IL-10、TGF-β）were also significantly up-regulated.The expression levels of anti-inflammatory factors in immune tissues were significantly up-regulated in the SeNPs0.4 group.2.On the 43rd day,the Schizothorax prenanti were exposed to 0.1mg/L cadmium for 21 days,（1）cadmium exposure for 1,7,14 and 21 days after SeNPs feeding,SOD and GSH-ST activity in serum increased significantly at each time point,and MDA content in serum of SeNPs0.4+Cd group was significantly lower than that of control group at each time point,compared with that of C+Cd group.Compared with group C,serum activities of GSH-Px,GSH-ST and SOD in SeNPs0.4+Cd group increased significantly at all time points,while those of group C+Cd group decreased significantly.（2）cadmium accumulation in each SeNPs dose group was less than that in the C+Cd group after cadmium exposure for 21d,and it showed a trend of significant decrease in muscle tissue.The selenium accumulation of middle intestine and muscle in each SeNPs dose group was significantly higher than that in other groups,and the selenium accumulation showed the deposition sequence of liver>muscle>middle intestine.Compared with the C and C+Cd groups,the contents of C3（C3）,ACH50 and ACP activity in the SeNPs dose group were significantly increased.Serum Ig M content increased significantly in SeNPs0.8+Cd group,CRP content increased significantly in SeNPs0.2+Cd and SeNPs0.4+Cd groups,and serum alkaline phosphatase（ALP）activity increased significantly in SeNPs0.4+Cd group.Cadmium significantly upregulated the expression of immune-related genes（TNF-α、IL-1β、IL-8etc.）,and the SeNPs0.4+Cd group could regulate the immune response of the Schizothorax prenanti to maintain the normal level.To sum up,SeNPs added to the feed can significantly improve the relative growth rate and specific growth rate of Schizothorax prenanti,as well as the antioxidant and immune capacity of the Schizothorax prenanti.After cadmium exposure,the accumulation of selenium in the muscles and intestines of the SeNPs group was significantly higher than that of the C and C+Cd groups.Cadmium accumulation in less than C+Cd set,and there was a significant reduction in muscle tissue,that may be SeNPs antagonism cadmium,promoted the eduction of cadmium,makes SeNPs to a certain extent,improve the cadmium stresses after oxidation resistance drop,cadmium exposure to play a protective role,improve the antioxidant capacity of qi Schizothorax prenanti mouth,and the ability to adjust his mouth s Schizothorax prenanti immune response to remain within the normal level;According to the above results,the comprehensive effect of 0.4mg/kg SeNPs was better than that of 0.2mg/kg and 0.8mg/kg SeNPs.