IGF-I and the truncated analogue des-(1 - 3)IGF-I enhance growth in rats after gut resection

Abstract

Effects of insulin-like growth factor I (IGF-I) administration and that of the truncated analogue des-(1 - 3)IGF-I have been examined in 170-g rats over a 7-day period after surgery to remove 80% of the jejunum plus ileum. The doses administered via osmotic infusion pumps were 0.96 and 2.4 mg·kg-1·day-1 IGF-I and 0.96 mg·kg-1·day-1 des-(1 - 3)IGF-I. All groups lost weight on the day after surgery, but over the next 3 days the des-(1 - 3)IGF-I and high-dose IGF-I groups stabilized better and subsequently gained significantly (P < 0.05) more weight than the vehicle or low-dose IGF-I groups over the last 3 days. The weight gains (mean ± SE) for the groups over this last 3-day period were 14.0 ± 1.7, 14.4 ± 2.9, 21.9 ± 1.7, and 20.8 ± 1.0 g for the vehicle, low-dose IGF-I, high-dose IGF-I, and des-(1 - 3)IGF-I groups, respectively. The nitrogen balances over the last 3 days for the high-dose IGF-I and des-(1 - 3)IGF-I groups, at 242 ± 14 and 217 ± 13 mg/d, respectively, were significantly (P < 0.05) more positive than the control group at 153 ± 21 mg/d. These differences could at least partially be explained by changes in muscle protein breakdown, as assessed by 3-methyl-L-histidine excretion. The kidneys were heavier in all treatment groups and the thymus after administration of des-(1 - 3)IGF-I. Anabolic effects of high-dose IGF-I and des-(1 - 3)IGF-I on the gut included a 45% heavier duodenal weight than in the controls (P < 0.001), heavier stomach weights, and increases in the total region not subjected to surgery. These results indicate that IGF-I, as well as des-(1 - 3)IGF-I at a lower dose, produce beneficial effects after surgical trauma in rats.