Study Of Protective Effects Of High Protein Diet On Intestinal Barrier In Food Restriction Rats And The Related Mechanisms

Objective: To study the protective role of high protein diet on the intestinal barrier function in food restricted rats and the related mechanisms. These would benefit to understand intestinal barrier damage caused by malnutrition and provide some guides for nutritional support to prevent the damage.Method: Forty male Wistar rats were randomly divided into five groups: control group was given 15% casein diet ad libitum, food restricted groups were pair-fed 15% casein diet with 50% or 30% intake of normal control respectively, protein upplemented groups were pair-fed 30% casein diet with 50% or 30% intake of normal control respectively. Blood and intestine samples were collected 1 or 2 weeks after pair-fed. The intestinal barrier function, immune function and the antioxidation indices were observed.Results: (1) The histomorphological picture of intestinal mucosa manifested thatthe damages of intestinal tissue in protein supplemented groups were slighter than thosein food restricted groups. Similarly, the endotoxin level and ratio of bacterialtranslocation in mesenteric lymph node and serum D-xylose level and diamine oxidase(DAO) activity of protein supplemented rats were significantly lower, while DAOactivity, SIgA, protein and DNA contents in mtestinal mucosa were higher, but thelatter two slightly. (2) Compared with food restricted rats, the activity of serum CAT inprotein supplemented rats was significantly higher and activity of serum SOD and theactivities of SOD and GSH-Px in intestinal mucosa and liver of protein supplementedgroups were also slightly increased. But the contents of MDA in serum and intestinalmucosa were decreased markedly. (3) The body weight and blood albumin level wereincreased in protein supplemented groups with significant reduction of both blood lipidsand fat pads around testis and kidney. (4) The thymus index and serum C4 level weresignificantly lower in protein supplemented groups while spleen index and serum C3level were only slightly increased. Serum IgM content was increased 2 weeks afterpair-fed in protein supplemented groups.Conclusion: Increased protein proportion in diet can prevent intestinal barrier dysfunction induced by malnutrition through reducing the damages of intestinal cell and mucosa, as related to permeability, immune function and antioxidation activities, then improving the nutrition status.