Abstract: To investigate regulating effects of taurochenodeoxycholic acid (TCDCA) on immune function in mice under heat stress,50 Kunming mice were divided randomly into five groups: normal control group,heat stress group,TCDCA1 group (50 mg/kg),TCDCA2 group (100 mg/kg),and TCDCA3 group (200 mg/kg). The mice of normal control group were fed in the temperature of 22 ℃,and the mice of other groups were treated with temperature of 35.5 ℃±0.5 ℃ and 60% humidity for 7 days. The spleen index,the change of T cell subgroup and B lymphocyte of peripheral blood,the contents of intestinal sIgA and serum IgG in mice were measured. The results showed that spleen index in mice of heat stress group was significantly lowered compared to the normal control group(P＜0.05);the contents of blood serum IgG and Intestinal sIgA were significantly (P＜0.05) higher;the percentage of CD8⁺ and CD19⁺ lymphocytes decreased significantly (P＜0.05),and the CD4⁺/CD8⁺ value increased significantly (P＜0.05),which demonstrated that the immune functions of mice under heat stress falls into disorders. The results also indicated that TCDCA have no effects on spleen index in heat stress,TCDCA enhanced the percentage of CD8⁺ and CD19⁺ lymphocytes in peripheral blood remarkably (P＜0.05),TCDCA recovered the CD4⁺/CD8⁺ value,remarkably and TCDCA decreased concentration of IgG in blood serum and sIgA in intestinal remarkably (P＜0.05). These findings suggested that the immunity of mice in heat-stress could be destroyed and leaded to disorder,and can be accumulated by TCDCA.

Key words: taurochenodeoxycholic acid; heat stress; immunological regulation