K. Fholenhag et al., EFFECTS OF INSULIN-LIKE GROWTH-FACTOR-I (IGF-I) ON THE SMALL-INTESTINE - A COMPARISON BETWEEN ORAL AND SUBCUTANEOUS ADMINISTRATION IN THE WEANED RAT, Growth factors, 14(1), 1997, pp. 81-88
Several studies have suggested that growth factors play an important r
ole in the development and the maintenance of the gastrointestinal tra
ct, Colostrum and normal breast milk as well as intestinal secretion a
re reported to contain IGF-I, Thus, the objective of this study was to
investigate whether the route of administration of IGF-I, subcutaneou
sly and orally, was important for the may of influencing the gastroint
estinal tract in the weaned rat and further to observe if this effect
was affected by different feed regimens. Well nourished weaned rats su
bcutaneously administered IGF-I (2 mg/kg body weight and day during 14
days) were found to have significantly increased relative weights of
the small intestine, increased duodenal crypt depths and villi heights
compared with control rats, The same dose given orally in bovine milk
had no effect, Furthermore, a study was performed with the same dose
of IGF-I given for 7 days together with a restricted feed regimen, Sim
ilar observations; although of a slightly smaller magnitude, were foun
d, These observations indicate that the effect of IGF-I on gastrointes
tinal renewal in the weaned rat is not depending on an IGF-I supply th
rough the gastrointestinal fluids but rather through a supply via the
circulation or by a local intestinal production,The effects were stati
stically significant both in well fed and malnourished conditions.