Mechanism Of Putrescine Regulates Enterocytes Proliferation And Intestinal Epithelial Restitution In Weanling Piglets

The intestine is an organ not only to digest and absorb nutrients but also to provide the first line barrier preventing bacterial invasion.The atrophy and dysfunction in the intestine induced by weaning usually causes piglet's diarrhea and decreased growth performance.Understanding repairing mechanism of intestinal damage caused by weaning is the key scientific question to answer.Putrescine is one of polyamines which have functions to enhance enterocytes proliferation and intestinal epithelial restitution,however,the underling mechanism is not clear yet.In this study,both in vivo feeding studies and in vitro cell culture were conducted to evaluate the effects of putrescine on porcine intestinal growth and function.In the in vivo feeding trial,72 weanling pigs were fed a corn-and soybean meal-based diet supplemented with 0,0.1,0.2 or 0.3% putrescine dihydrochloride to study the effect of different levels of dietary putrescine supplementary on growth performance,dearrhea rate and intestine morphology.In the in vitro,the porcine intestinal epithelial cells(IPEC-J2),originally isolated from jejunal epithelial of a neonatal unsuckled piglet,was selected as a model to study the different expression of MAPK/ERK and FAK under the condition of extracellular putrescine supplementation when cellular putrescine synthesis was blocked or not,to study the key pathway that involved in putrescine influencing IPEC-J2 cell proliferation and migration.In the in vitro an inflammation model,IPEC-J2 were challenged with lipopolysaccharides(LPS)in the presence of 200 ?mol/L putrescine.qPCR and western blotting were used to determine the expression of key genes and proteins in mediating putrescine functions.Dietary supplementation with 0.2% putrescine dihydrochloride had no effect on the growth performance of weanling piglets,but decreased the incidence of diarrhea with an improvement in intestinal morphology,significantly increased zonula occluden 1(ZO-1)and Occludin mRNA abundance and had a trend to increase Claudin-1 mRNA abundance.Extracellular supplementation with 200 ?mol/L putrescine,promoted cell proliferation and migration.Inhibition of ornithine decarboxylase activity decreased the proliferation and migration of IPEC-J2 cells,and this effect was alleviated by the supplementation with putrescine.The phosphorylation of extracellular signal regulated kinase(ERK)1/2 and focal adhesion kinase was enhanced by putrescine.LPS increased the expression of inflammatory cytokines tumor necrosis factor ?(TNF-?),interleukin 8(IL-8)and IL-6,and inhibited cell proliferation and migration in IPEC-J2 cells.Adding exogenous putrescine suppressed the expression of TNF-?,IL-8 and IL-6,and recovered cell migration and proliferation in LPS-treated IPEC-J2 cells.Putrescine supplementation also reduced the gene expression of TNF-?,IL-8,IL-6 and NF-?B P65 in the jejunal mucosa of piglets.Our results provide a new strategy to improve intestinal integrity and health in weanling piglets and also have important implications for nutritional management of other neonates.