Effects Of Cold Stress On Chicken's Barrier Function Of Intestinal Mucosa

The intestinal tract is continuously exposed to the external environment,meanwhile intestinal mucosa has very unique dissection character in its blood vessels which leaves intestinal tract the target organ easiest affected by stress. The influence of stress on gastrointestinal is increasingly being recognized, the mechanisms involved in the process have been a popular investigation subject in recent years. The cold stress, as one of the stressors, commonly existed in the cold region; the effects of cold stress on newborn animal are extraordinary. There were many reports concerned to rodents exposed in cold stress environment, but few studies focused on poultry. In this study, 180 1-d-old male chicks were randomly allocated to 12 groups (30 chicks in each group), 6 groups were treated with acute cold stress (0 h,1 h,3 h,6 h,12 h ,24 h) and 6 groups were treated with chronic cold stress (5 d,10 d,20 d). In this study, the D-xylose absorption test is used as a measurement of intestinal mucosa permeability. To exam the function of intestinal mucosa, DNA and protein content of jejunum mucosa were detected, morphology structure of chicken's jejunum was observed in microscope and ultra microscope. COX-2 mRNA and Occludin mRNA expression in jejunum, CRH mRNA expression in hypothalamus, Gln content in serum and jejunum, PGE2 content in jejunum, TchE content in serum, numbers of mast cells in jejunum mucosa were detected to reveal the possibility mechanisms involves in cold stress induced intestinal barrier dysfunction. The results show that:1. Cold stress could increase intestinal barrier permeability and change mucosa epithelium of chicken jejunum, DNA and protein content of jejunum mucosa indicated that proliferation of mucosa cells decreased.2. Intestinal mucosa barrier function could be damaged when exposed to cold stress and the mechanisms involved in the process might include mediator released by mast cells, acetylcholine and CRH releasing.3. When exposed to cold stress, the consumption of Gln increased in general, the content of Gln decreased both in serum and in jejunum mucosa.It indicated that Gln deficiency in intestinal mucosa is part of the reason that intestinal mucosa permeability increased when exposed to cold stress .4. The expression of Occludin mRNA in chicken's jejunum decreased after long term exposure to cold stress, indicating that might be one of the approaches in the process of intestinal mucosa permeability increasing induced by cold stress.5. PGE2 is mediated by COX-2, cold stress can increase the expression of COX-2 mRNA in chicken's jejunum which lead to the over expression of PGE2. Expose to over expression PGE2 would cause inflammation in intestinal mucosa and eventually develop intestinal mucosal dysfunctionIn this study, we reveals the change of intestinal mucosa when expose to cold stress and mechenisams involved in the process through observing aspects mentioned above. Our aim is to explore methods which can improve poultry's cold-resist ability so as to provide a scientific basis and experimental foundation for maintaining animals'normal physiological functions in cold stress environments.