GH receptor immunoreactivity is found throughout the gastrointestinal tract
. GH has proliferative effects upon intestinal epithelium, and influences e
nteroendocrine cell secretion, calcium absorption, and intestinal amino aci
d and ion transport. The proliferative effects of GH may be reflected in th
e increased incidence of neoplastic colonic polyps in individuals with long
-term GH excess reported by some investigators. CH also increases hepatic c
ytochrome P450 expression, potentially altering drug and steroid hormone me
tabolism.
Current clinical research efforts include the use of exogenous GH as a stim
ulant of gut growth and adaptation in patients who have undergone massive i
ntestinal resection. Exogenous CH is also being studied in animal models of
critical illness where it appears to increase intestinal glutamine uptake,
which may prevent deterioration of the intestinal mucosal barrier.