| Popis: |
Growth Hormone (GH) is well known to have prominent anabolic effects on bone, muscle and fat, but its effects on the gastrointestinal tract are less well studied. The fact that recombinant GH therapy has been used to treat intestinal diseases such as short bowel syndrome and inflammatory bowel disease indicates that GH can exert effects in the intestines. However, little is known about the basic biological effects of GH on this organ. The focus of this study was to examine the effects of GH in the absence of intestinal disease using genetically altered mice. Mice with systemic alterations in GH activity displayed morphological and metabolic changes that correlated with levels of GH action. In a mouse model with the GH receptor (GHR) gene disrupted in intestinal epithelial cells, there were sex specific changes in intestinal length, glucose metabolism, barrier function, and fat absorption, but no apparent changes in mucosal morphology. In other experimental models, genetically engineered mice with chronically increased GH showed increases in collagen protein content with no detectable change in collagen gene expression. Mice with chronically decreased GH showed a decrease in collagen protein content with no significant change in collagen gene expression. An increase in collagen gene expression was observed in wild-type mice after one month of daily injections of GH. These findings establish some effects of GH action on the intestines and encourage further examination of intestinal GH induced signaling on overall animal physiology. |
