Growth hormone treatment of rats with chronic diverting colostomy. Differential response on proximal functioning and distal atrophic colon

Diversion of colon from the fecal stream leads to profound intestinal atrophy. After diverting colostomy for 4 weeks, female rats were treated with biosynthetic human growth hormone (b-hGH; 2.0 mg.kg-1 body wt.day-1) in order to investigate whether b-hGH could reverse atrophic changes in distal colon, with special reference to changes in morphometric composition, collagen content and biomechanical properties. Biosynthetic hGH treatment for 28 days stimulated growth of the muscularis propria of the defunctioned, atrophic colon (p < 0.05), whereas the mucosal atrophy was unaffected by the treatment. In colon proximal to the colostomy, however, b-hGH increased the colonic wet weight (p < 0.01), defatted dry weight (p < 0.005) and the collagen content (p < 0.05). Morphometric analysis showed that the growth increase was localized to the mucosa and the muscularis propria. In conclusion, fecal diversion alters the response of b-hGH treatment and indicates that the trophic effect of growth hormone on colonic mucosa is dependent on fecal bulk passage, whereas the trophic effect on muscularis propria is fully retained when colon is deprived of luminal nutrients.