Epidermal growth factor improves intestinal morphology by stimulating proliferation and differentiation of enterocytes and mTOR signaling pathway in weaning piglets

Epidermal growth factor (EGF) has been shown to improve piglet intestinal morphology and epithelial recovery. In an attempt to further understand the mechanisms behind these improvements, this study tested the hypothesis that dietary EGF may affect intestinal morphology by stimulating the proliferation and differentiation of enterocytes in weaning piglets. In piglets receiving 200 mu g kg(-1) EGF, crypt depth and villus height increased (P<0.05). Adding 400 mu g kg(-1) EGF increased villus height-to-crypt depth ratio (P<0.05), but reduced crypt depth (P<0.05). Dietary supplementation with 200 mu g kg(-1) EGF significantly increased the number of Ki67-positive cells (P<0.01) and tended to increase the mRNA level of proliferating cell nuclear antigen (P<0.10). However, this supplementation decreased the expression level of intestinal fatty acid-binding protein (P<0.05). Piglets fed with 400 mu g kg(-1) EGF had an increased mRNA level of intestinal alkaline phosphatase (P<0.05). The phosphorylation of mTOR (mammalian target of rapamycin) was observed in the 200 mu g kg(-1) EGF group. These results suggest that dietary supplementation with a low level of EGF improved piglet intestinal morphology through stimulating the proliferation and differentiation of enterocytes, and the mTOR signaling pathway may partly be involved in this process.