The developmental changes in intestinal epithelial cell proliferation,differentiation, and shedding in weaning piglets

Intestinal epithelial homeostasis plays an important role in intestinal morphology and function. However, the developmental changes in intestinal epithelial cell turnover in piglets during early weaning are unknown so far. Thus, the aim of this work was to detect changes in piglet gut development from weaning to post-weaning d 14. Accordingly, 40 piglets were used in the present study, and 8 piglets were randomly selected for sampling at d 0, 1, 3, 7 and 14 post-weaning, respectively. The results showed that weaning stress significantly affected small intestinal morphological architecture, and this impact was the worst on d 3, and then returned to normal on d 14. Furthermore, the number of the marker of proliferation Ki-67(Ki67) positive cells was decreased on d 1 and 3, and then recovered on d 14(P < 0.001).Also, weaning strikingly increased jejunal epithelial cell shedding on d 1 to 7 compared on d 0(P < 0.05).Moreover, weaning remarkably affected the number of small intestinal enterocytes, goblets and endocrine cells(P < 0.05), and there were also significant differences in genes expression related to proliferation and differentiation(P < 0.05). Additionally, the mechanistic target of rapamycin(mTOR)phosphorylation level was higher on d 3(P < 0.05). However, the Wingless/Int1(WNT)/β-catenin pathway was not influenced by post-weaning days. Taken together, weaning induced noteworthy changes in intestinal epithelial cell proliferation, differentiation and shedding, and the mTOR signaling pathway was involved in this process. Our findings provide a cellular mechanism for intestinal developmental changes during weaning periods. This may provide nutritionists with better insight into designing efficient in-feed alternatives for preventing the unfavorable gut development in weaning piglets.