中文摘要：

本试验旨在利用地塞米松构建应激模型,研究应激对肉仔鸡肠道小肽吸收的影响。选取200只21日龄、体质量相近的雄性Arbor Acres（AA）肉仔鸡,随机分为4个处理,每只腹部皮下连续7 d注射1 mL地塞米松磷酸钠注射液（不同处理注射剂量分别为0、0.1、0.52、.5 mg.kg-1BW）。最后一次注射8 h后（15：00）空腹称取体质量,采血、取空肠,进行组织学、皮质酮、小肽Gly-Sar吸收和小肽转运载体PepT-1 mRNA表达的检测,结果表明：⑴地塞米松显著降低肉仔鸡体增质量（P〈0.05）;⑵地塞米松显著抑制肉仔鸡空肠外翻肠囊及刷状缘囊膜对小肽Gly-Sar的吸收（P〈0.05）;⑶地塞米松显著增加肉仔鸡空肠隐窝深度（P〈0.05）,显著降低绒毛高度、吸收面积和绒毛高度/隐窝深度比值（P〈0.05）,对绒毛宽度影响不显著（P〉0.05）;⑷地塞米松显著降低肉仔鸡空肠小肽载体PepT-1 mRNA的表达量（P〈0.05）。由本试验推测应激可抑制肉仔鸡小肽吸收,产生原因与空肠黏膜形态受损及小肽转运载体PepT-1 mRNA表达量受到抑制有关。

英文摘要：

The study was conducted to investigate the effects of stress on the Absorption of small peptides in the intestine of broilers.200 21-day-old male Arbor Acre broilers with similar body weight were randomly assigned into four groups and were injected subcutaneously in the abdomen with 1 mL dexamethasone（0,0.1,0.5 and 2.5 mg·kg-1 BW） for 7 d.The body weight was measured 8 hours post the last injection on a fasting state,and the entire jejunum was collected.Histological study of jejunum was conducted,Absorption of Gly-Sar,content of plasma corticosterone,and expression of peptide transporter 1 mRNA of the broilers were analyzed.The results demonstrated that：（1）Dexamethasone reduced growth of the broilers（P〈0.05）;（2） Dexamethasone inhibited Absorption of Gly-Sar by jejunum gut sacs and brush border membrane vesicles of the broilers（P〈0.05）;（3）Dexamethasone increased the crypt depth of the jejunum and decreased the villus height,Absorption area and ratio of villus height to crypt depth（P〈0.05）.No significant effect on villus width was observed（P〉0.05）;（4）Dexamethasone inhibited expression of peptide transporter 1 mRNA of the broilers（P〈0.05）.Based on this study,it could be concluded that stress inhibited the Absorption of small peptides in broilers,the reasons may be related to the impairment of intestine mucosal morphology and the inhibition of expression of PepT-1 mRNA.