Effect of growth hormone on small intestinal homeostasis relation to cellular mediators IGF-I and IGFBP-3.

Aim: To evaluate the effects of growth hormone (GH) on the histology of small intestines which might be related to the role of insulin like growth factor (IGF)-I, IGF-binding protein 3 (IGFBP-3) and its receptors.

Methods: Twelve week-old adult male Wistar albino rats were divided into two groups. The study group (n = 10), received recombinant human growth hormone (rGH) at a dose of 2 mg/kg per day subcutaneously for 14 d and the control group (n = 10) received physiologic serum. Paraffin sections of jejunum were stained with periodic acid shift (PAS) and hematoxylin and eosin (HE) for light microscopy. They were also examined for IGF-I, IGFBP-3 and IGF-receptor immunoreactivities. Staining intensity was graded semi-quantitatively using the HSCORE.

Results: Goblet cells and the cells in crypt epithelia were significantly increased in the study group compared to that of the control group. We have demonstrated an increase of IGF-I and IGFBP-3 immunoreactivities in surface epithelium of the small intestine by GH application. IGF-I receptor immunoreactivities of crypt, villous columnar cells, enteroendocrine cells and muscularis mucosae were also more strongly positive in the study group compared to those of in the control group.

Conclusion: These findings confirm the important trophic and protective role of GH in the homeostasis of the small intestine. The trophic effect is mediated by an increase in IGF-I synthesis in the small intestine, but the protective effect is not related to IGF-I.