Effect Of Vitamin E On Intestinal Function And Epithelial Cell Proliferation And Differentiation In Weaned Piglets And Its Mechanism

Weaning stress in piglets often leads to changes in intestinal morphology,decreased digestion,absorption and feed intake,and may also lead to inflammation and oxidative stress,which are associated with the proliferation and differentiation of the small intestine component,the intestinal epithelial cells.Studies have shown that the essential vitamin E(VE)in feed can affect intestinal function,but whether it affects the proliferation and differentiation of intestinal epithelial cells in intestinal mucosa is unclear.21-day-old weaned piglets were used as experimental subjects to study the effects of VE on intestinal mucosal morphology,digestive enzyme activity and nutrient transport in weaned piglets,and further study of VE on piglet small intestine epithelium by means like qPCR,Immunohistochemistry and WB were done to understand the effects and intrinsic mechanisms of these cells' proliferation and differentiation.Test 1: Twenty-four 21-day-old weaned piglets [(Yorkshire ×Landrace)× Duroc] randomly divided into 4 groups,feeding diet containing 16 IU,32IU,80 IU and 160 IU Vitamin E.Each group has 6piglets,with each pen holding one piglet.The trial period was 7 days and all animals were sampling at the end of the experiments.Test 2: Thirty 21-day-old weaned piglets [(Yorkshire × Landrace)×Duroc] randomly divided into 5 groups,feeding diet containing 0IU,16 IU,32IU,80 IU and 160 IU Vitamin E.Each group has 6 piglets,with each pen holding one piglet.The trial period was 14 days and all animals were sampling at the end of the experiments.Results:(1)Effects on growth performance,intestinal function of digestion and transportation and blood biochemical parameters of weaned piglets: On the 7th day of experiment,VE had an increasing trend of average daily gain and daily feed intake(0.05<P<0.1).On the same time,some indexes of duodenum and jejunum had an influential trend(0.05<P<0.1).On the 14 th day of experiment,adding VE tended to reduce the depth of crypt(0.05<P<0.1),and the width of jejunum was significantly decreased(P<0.05).At the previous time,the addition of32 IU of VE significantly increased mucosal lactase and alkaline phosphatase activities(P<0.05).At the second time,the concentration of sucrase decreased with the increase of VE concentration comparing with the control group(P<0.05).The treatment of the first 7 days resulted in a significant decrease and then an increase as the concentration of VE increase in the intestinal jejunal glutamate transporter Slc1a1 in weaned piglets(P<0.05).On the 7th day of the experiment,VE significantly increased the concentration of cholesterol(P<0.05),and tended to increase aspartate aminotransferase,low-density lipoprotein cholesterol and glucose in the blood(0.05<P<0.1),while the concentration of NH3 L was significantly decreased under the same VE concentration treatment(P<0.05).At 14 days of treatment,ALT concentration was significantly increased(P<0.05),and the concentration of IgM was significantly decreased(P<0.05).(2)Effects on the intestinal epithelial cells proliferation,the relationship between antioxidant and signaling pathways,on the differentiation of goblet cells: On day 14,the number of crypt cells in the 80 IU VE group was significantly lower than that in the control group(P<0.05).On the 7th day of the experiment,the content of malondialdehyde(MDA)in the jejunal mucosa was significantly lower than that of other concentrations in the 80 IU VE group(P<0.05),and there was an increasing trend on the 14 th day(P<0.1).On day 7 and 14,VE significantly increased Ctnnb1 mRNA expression(P<0.05),while the expression of Notch1 was significantly increased in the first 7 days(P<0.05).By day 14,there was a significant decrease on the expression of Dll1 in the 32 IU group(P < 0.05).On the 7th day of experiment,as the dose of VE increased,the number of goblet cells in jejunal crypt increased while which decreased in ileum villi(P<0.05).On the 14 th day of experiment,adding 80 IU VE increased goblet cells in the ileum significantly(P<0.05),and tended to decrease them in the crypt of ileum(0.05<P<0.1).(3)Effects on the expression of inflammatory factors in jejunum and ileum: On the 7th day of experiment,the expression of jejunalinflammatory factors Il-1b and Tnf-a was higher than that of other concentrations of VE treated group when feeding 32 IU of VE(0.05< P <0.1).At 14 days of treatment,the mRNA expression of Il-22 and Tnf-a were significantly lower than non-processing when treat VE(P<0.05),while Il-10 expression was significantly increased(P<0.05).On day 7,the mRNA expression of Tff3 was significantly lower in 16 IU than in other high-concentration VE-treated groups(P<0.05),and the expression of Fasn at this concentration was significantly higher than that in the other groups(P<0.05).The mRNA expression of Muc2 was the lowest when adding 160 IU VE(P<0.05),and the expression of Tlr4 was significantly increased with the increase of VE concentration(P<0.05).The Scd tend to be influenced by VE on day 14 to reach the highest at32IU(P>0.1).Il-22 increased significantly(P<0.05)and and Tlr2 tended to increase(P<0.1)in the same concentration of 16 IU.So did Il-1b increased significantly(P<0.05)and Tnf-a tended to increase(P<0.1)in32IU group.Conclusions: Dietary VE can affect the intestinal morphological structure and function of weaned piglets and inhibit the proliferation of jejunal epithelial cells by affecting the mRNA expression of anti-inflammatory factors.By affecting pro-inflammatory factors and lipid metabolism genes expression,goblet cells differentiation may be affected.