Effects Of Excessive Iron On Intestinal Mucosa And Intestinal Flora In Rats

Objective: Excessive intake of dietary iron or excessive iron supplementation to prevent iron deficiency anemia may have adverse effects on the body.At present,there were few studies about the effect of excessive iron on intestinal tract.Therefore,we established a model of excessive intake of iron in rats to study the effect on intestinal mucosa and intestinal flora,and explore its possible mechanism.Methods: 48 male Wistar rats were randomly divided into 4 groups by body weight: Low Iron Group(LI),Normal Iron Group(NI),Medium Iron Group(MI),and High Iron Group(HI).Iron concentration in foodstuff were 50 ? 120 ? 250 and 1250mg/kg,respectively.The rats were fed with deionized water for 8 weeks,meanwhile,the general condition,body weight and food intake were documented.Fecal samples of each rat were collected at the end of 8 weeks.At the end of the experiment,rats were anesthetized in abdominal cavity with 10% chloral hydrate(0.5m L/100g·bw).The rats were sacrificed after blood,which was kept in-80 o C after serum separation to detect serum ferritin(SF),endotoxin,tumor necrosis factor(TNF-a)levels.Intestinal homogenate was made to determine interleukin 6(IL-6),interleukin 10(IL-10)and secretory immunoglobulin A(SIg A),malondialdehyde(MDA),total superoxide dismutase(T-SOD),and glutathione peroxidase(GSH-PX).Pathological changes of intestinal tissue were observed in each rat by HE staining.The specific primers of Bifidobacterium,Lactobacillus,Enterococcus and Escherichia coli were designed by 16 S r DNA sequences of bacteria.The copy numbers of16 S r DNA were determined by real-time fluorescence quantitative PCR reaction to analyze numbers of four kinds of bacteria,which was extracted from fecal samples.16 S r DNA high-throughput sequencing was used to analyze molecular ecology of intestinal bacteria in feces.Results: At the eighth week,the average weight of the rats in the GI group decreased by20% than that in the NI group(P<0.05),and the average intake of food decreased by11.9%(P<0.05).The expression level of IL-6 in the small intestine tissue of the GI group was 108.6 pg/m L,which was significantly higher than that of the NI group(84.7 pg/m L,P<0.05).The expression level of IL-10 and SIg A of the GI group were 50.5 pg/m L and62.3 pg/m L,which were both significantly less than those of the NI group(71.7pg/m Land 67.1 pg/ml,P<0.05).Compared with the NI group,the levels of serum endotoxin were significantly decreased in the LI group,and higher in the GI group(P<0.05).Compared with the NI group,the level of TNF in the MI group and the GI group increased significantly(P<0.05).Compare with the NI group,the SOD level in the GI group decreased by 32.3% and decreased by 11.9% in the medium iron group(P<0.05).The MDA level of the GI group and the MI group increased by 139.9% and33.7%(P<0.05).The results of histological analysis showed that the intestinal mucosa showed normal in the LI and NI groups;slight damage in the MI group-the top microvilli was slightly shed;and in the GI group,the villi shape was irregular,and some intestinal epithelial cells were necrotic.Analysis of main microflora in intestinal tract showed that the number of fecal Lactobacilli and Bifidobacterium of the GI group decreased significantly(P<0.05)compared with the NI group,and the number of Escherichia coli increased significantly(P<0.05).The top 5 kinds of bacteria in each group distributed differently.Excessive intake of iron may cause diversity of the intestinal flora decreased,and the fungus changed too.Conclusion: Excessive dietary intake of iron can affect the normal growth and development of rats,and also cause inflammatory lesions in the small intestine.The unbalance of intestinal flora in rats can be caused too,including the decrease of Lactobacilli and Bifidobacterium,which may be related to the elevation of TNF-a and endotoxin in serum.