Effects of Growth Hormone and Insulin-Like Growth Factor-I on Radiation Enteritis

Abstract

The effect of growth hormone (GH) and insulin-like growth factor-I (IGF-I) on intestinal mucosal integrity and bacterial translocation after abdominal radiation was studied in rats. Animals were divided into the following groups: I (control), II (radiation), III (radiation plus GH) and IV (radiation plus IGF-I). Radiation (1,100 cGy) was administered on the 1st day to groups II, III and IV. GH [0.25 mg/kg body weight (BW) s.c. once daily] was administered on days 1, 2 and 3 to group III, and IGF-I (0.1 mg/kg BW s.c. twice daily) was given on days 1, 2 and 3 to group IV. On day 4, animals were sacrificed. Cultures of the mesenteric lymph nodes (MLN) and blood cultures from aorta and portal vein were performed. The number of villi per centimeter (V/cm), the villus height (Vh), mitoses per crypt (M/C) and protein and DNA contents of the mucosa were evaluated in samples from the terminal ileum. Radiation increased the number of positive MLN cultures, while treatment with GH and IGF-I reduced them significantly. V/cm, Vh, M/C, protein and DNA contents were significantly increased in all irradiated animals treated with GH and IGF-I. In conclusion both GH and IGF-I are not only capable of improving the mucosal integrity but also to reduce the bacterial translocation that follows intestinal radiation. In small doses IGF-I could reproduce the effects of GH and in some parameters the effects were more pronounced, although not statistically significant. This suggests that the effects of GH on intestine could be mediated through the local and systemic generation of IGF-I.