Biomechanical properties of ileum after systemic treatment with epithelial growth factor

摘要

AIM: Systemic treatment with epidermal growth factor (EGF) leads to growth of all parts of the small intestine in normal functioning rate. In this study, we investigated the effect of this growth process on morphometric and biomechanical parameters of ileum. METHODS: Rats were treated with EGF (150 μg·kg~(-1) day~(-1)) or placebo via osmotic minipumps for 2, 4, 7, and 14 days. A segment of ileum was removed. The morphology at no-load state and zero-stress state was measured and passive biomechanical properties were assessed using a biaxial test machine (combined inflation and axial stretching). RESULTS: The ileum weight increased after EGF administration. After 4 days' EGF treatment, the wall thickness was increased. Significantly smaller inner perimeters were seen in 4 day and 7 day EGF treatment groups. The opening angle and residual strain began to increase after 7 days' EGF treatment. Wall stiffness, evaluated from the stress-strain curves, showed a continuous decrease in circumferential direction during the first 7 days' EGF treatment. The longitudinal stiffness increased during the first 7 days. The stress-strain curves for both circumferential and longitudinal direction tended to shift back to normal 14 days after starting EGF administration. CONCLUSION: EGF can cause significant changes both in the morphology and in the passive mechanical properties of the rat ileum.