Effects Of Gut Microbiota On The Structure Of Intestinal Mucosa An Immune Function And Fat Metabolism Of Chicks

The gnotobiotic chicks was selected as a model to study the function of intestinal microbiota on intestinal mucosal morphology, immune function, fat metabolism and fat metabolism-related genes expression. The result would reveal the function and mechanism of the gut microbiota.ExperimentⅠ: Establish a gnotobiotic chicken modelTo reveal the relationship and mechanism of intestinal microbiota with its host. SPF eggs were hatched in incubator and chicks were transferred to keep in isolator, feed ration was irradiated by Co-60, water was steriled by autoclave(121℃,20min). After two weeks old of age, chicken excrement was detected by different culture medium following as GB/T 14926.41-2001.The results that bacteria were not been detected, the model of gnotobiotic chicken was successfully established.ExperimentⅡ:Effects of gut microbiota on Intestinal Mucosal Morphology and Immune Organs Development of Gnotobiotic ChicksThe gnotobiotic chicks were selected as a model in this study to investigate the effects of chicken-origin Lactobacillus and chicken cecal microbial on intestinal development and mucosal morphology and immune organs development of chicks. After21 d aseptic hatching for 80 SPF Eggs, 60 healthy chicks were transferred to 3 gnotobiotic isolators(3 group and 20 chicks for per group), and were fed a basal sterile diet(CT group), the basal sterile diet +Lactobacillus culture(LB group), he basal sterile diet+chicken cecal contents(CON group). Six chicks were slaughtered from 3 groups at 7, 14,21 days of age, the intestinal long mucosal morphology and immune organs weight were measured. The results showed as follows: Compared with CT groupt, the jejunum length of chicks added with Lactobacillus or cecal contents were higher, cecal length and volume were lower. The spleen index was significantly higher than that of the CT group(P<0.010). Compared with gnotobiotic chicks, the crypt depth of duodenum, jejunum and ileum was decreased; the villi height/crypt depth(V/C) of duodenum, jejunum and ileum was increased for the chicks added with Lactobacillus or cecal contents. It is concluded that, intestinal microbiota can promote intestinal development, narrowing the cecum volume; while promoting the development of spleen, liver, thymus and bursa, enhancing immunity.Experiment Ⅲ: Effects of intestinal microbiota on the fat metabolism of chicksThe experiment design was the same as ExperimentⅡ. After 21 days, blood biochemical parameters, liver fat content and abdomina fat, fat metabolism-related genes expression were determined. The results showed: The rate of abdominal fat, gizzard, liver fat content were significantly increased(P<0.05). The levels of total serum protein,serumAlbumin, serum glucose, and serum triglyceride were improved In LB and CON groups.While there was a contrary result on The levels of serum cholesterol, high-density lipoprotein and low-density lipoprotein(P<0.05). The m RNA expression of adipose LPL,adipose THRSP, adipose PPARγ were higher in LB and CON groups. THRSP m RNA expression levels were very significantly upregulated(P<0.01), PPARγ m RNA expression levels were significantly upregulated(P<0.05). Hepatic SREBP-1, Ch REBP m RNA expression levels increased(P<0.05). While no significant line effect were identified in the expression profiles of hepatic ACC and FAS gene(P>0.05). There was lower FAS expression in jejunum(P<0.05), while the m RNA expression of L-FABP increased(P>0.05). It was concluded that, intestinal microbiota can affect lipid metabolism by regulating the expression of genes related to fat metabolism.Experiment Ⅳ: Effects of intestinal microbiota on the immune organs and immune function of gnotobiotic ChicksThe gnotobiotic chicks were selected as a model with which to study the effects of intestinal microbiota combined with ND on the immune organs and immune function of Chicks. After 21 d aseptic hatching for 80 SPF Eggs, 60 healthy chicks were transferred to3 gnotobiotic isolators(20 chicks for one group), were fed with basic Sterile diet(CT),basic sterile feed +Lactobacillus culture(LB), sterile feed +chicken cecal contents(CON).Newcastle disease vaccine Subcutaneous injection after 21 days. 6 chickens were slaughtered from 3 groups at 1, 7, 14, days after immunization. respectively, serum biochemical parameters, immunoglobulins, immune organ level, antibody levels, Small intestinal mucosal secretion amount of SIg A were determined. The results showed:(1)Liver and spleen index were improved in LB group after Newcastle immunization.(2)The levels of serum total protein, albumin, Ig G and Ig M were were significantly decreased during 1-7d after immunization,while the levels of Ig A increased1 d after immunizationin in LB group(P<0.05).(3)1 day after immunization,ND antibody levels were significantly improved in LB group and CON group(P<0.05),whlie there was no significant effect on ND antibody levels in LB group during the latter part of the immune.(4)There was a significant effect on duodenal mucosa SIg A secretion(P<0.05),but No significant effect on Jejunum 7d after immunization in LB group.;There was a significant effect on Jejunum mucosal SIg A secretion(P<0.05),but no significant effect on duodenal mucosa in CON group. This experiment shows that intestinal microbiota and Newcastle disease vaccine were interaction to influence of the chicken Immune function.