Effects of Astragalus polysaccharides on growth performance,antioxidant capacity,and immune function in Cynoglossus semilaevis

HAO Shuang; YOU Hongzheng; JIANG Jufeng; GU Dexian; KAN Zheng; MA Lin; LUO Xin; ZHANG Nan

doi:10.13557/j.cnki.issn1002-2813.2025.08.009

Abstract：The study aimed to investigate the effects of Astragalus polysaccharides(APS)on the growth performance,antioxidant capacity,and immune function in Cynoglossus semilaevis.The experiment consisted of two parts.The first part involved an in vitro immune induction test,where peripheral blood leukocytes of Cynoglossus semilaevis were incubated with cell culture medium containing 10,100,or 1 000 mg/L APS to measure immune cell activity and in vitro induction of immune-related gene expression.The second part was an in vivo feeding trial,in which 240 Cynoglossus semilaevis were randomly divided into four groups(three replicates per group,20 fish per replicate).The control group(Group C)was fed a basal diet,while the experimental groups(Groups A1,A2,and A3)were fed the basal diet supplemented with 0.1%,0.2%,and 0.4%APS,respectively,for 28 days.Results showed that compared to the control,1 000 mg/L APS significantly enhanced cellular respiratory burst activity(P<0.05)and upregulated interleukin-8(IL-8)and tumor necrosis factor-α(TNF-α)expression in leukocytes at 12,24,and 48 h(P<0.05).After 28 days of feeding,the final body weight,weight gain rate,and specific growth rate in Groups A2 and A3 were significantly higher than those in Group C(P<0.05).In Group A3,serum superoxide dismutase(SOD)and catalase(CAT)activities on days 7 and 21,as well as serum interferon(IFN)content,were significantly higher than in other groups(P<0.05).Serum lysozyme(LZM)activity on days 21 and 28 in Group A3 was also significantly elevated(P<0.05).In Group A2,SOD and CAT activities on day 7 were significantly lower than in Group C(P<0.05),while serum complement 3(C3)content was significantly higher(P<0.05).All experimental groups exhibited significantly higher splenic IL-1β mRNA expression than Group C(P<0.05).On day 21,IL-1β and IL-8 mRNA expression in the head kidney and blood of Group A3 were significantly higher than in other groups(P<0.05).On days 7,14,and 21,splenic IL-8 mRNA expression in Groups A2 and A3 was significantly higher than in Group C(P<0.05).On day 28,blood Toll-like receptor 2(TLR2)mRNA expression in all experimental groups was significantly elevated compared to Group C(P<0.05).On days 7 and 21,head kidney TLR2 mRNA expression in Groups A2 and A3 was significantly higher than in Group C(P<0.05),while splenic TLR2 mRNA expression in Group A3 was significantly higher than in other groups on days 7 and 14(P<0.05).This studys show that APS exhibits immunostimulatory effects on Cynoglossus semilaevis peripheral blood leukocytes in vitro,and dietary supplementation with APS improves growth performance,antioxidant capacity,and immune function in Cynoglossus semilaevis,with 0.4%APS showing the optimal efficacy.