中文摘要：

选用400只14日龄的AA肉公雏，随机分配到4个处理组中，分析注射LPS对内分泌激素和免疫机能的影响。16、18和20日龄，处理组从腹膜注射LPS，对照组注射生理盐水。在最后一次注射后第2、4、8和24h，测定血清皮质酮、PGE2、T3和T4水平，21日龄测定T、B淋巴细胞转化率、T细胞亚群、脾脏IL-2和IFN-γ的mRNA的表达量，23和27日龄测定新城疫抗体滴度。结果表明：脂多糖使皮质酮、PGE2水平和T4／T3比值升高，使T3水平降低，注射后8h基本恢复正常；使淋巴细胞转化率、CD3^＋T和CD4^＋T的比例升高，但不影响新城疫抗体滴度；使脾脏中IL-2和IFN-γ的mRNA的表达量增加。注射LPS使肉仔鸡发生了以细胞免疫为主的应激反应，皮质酮和T3水平、T4／T3比值及细胞因子mRNA表达量均能作为衡量免疫应激的敏感指标；免疫应激是相对于正常状态而言的，就其本身来说，尚无法衡量程度的高与低。

英文摘要：

Four hundreds 14-d-old AA male broilers were randomly assigned to one of four treatments to investigate the effect of LPS challenged on endocrine hormone and immune function. On day 16,18 and 20,chicks were given intraperitoneal injection of sterile saline containing LPS respectively. Blood samples were taken at 2,4,8,and 24 h after the third injection, serum levels of cortisone,PGF4 ,T3 and T4 were determined. Lymphocyte blastogenesis and T lymphocyte population were analysized 1 d after the LPS administration,gene expression of IL-2 and IFN-γ was quantified by RT-PCR technology. Antibody titers to NDV was measured on the 23 and 27-d-old. In chicks receving LPS,the level of cortisone and PGE2, and the ratio of T4/T3 were increased, but the level of T3 decreased, at 8 h after injection, there were no significant difference except cortisone among treatments. Chicks with LPS administration had higher lymphocyte proliferative response to mitogens than those with only receving saline,and the ratio of CD3^＋ T, CD4^＋ T was higher, LPS also promoted the mRNA expression of IL-2 and IFN-γ in spleen. Antibody titers to NDV was not affected by LPS administration. These results suggested that LPS challenge induced immunological stress in broilers, which was mainly cell-mediated immune response;the levels of cortisone and Ta ,the ratio of T4/T3 and gene expression of CKs were all sensitive parameters for evaluating immunological stress; and immunological stress was relative, we can not define the degree of it.