Intestinal protein and LPH synthesis in parenterally fed piglets receiving partial enteral nutrition and enteral insulinlike growth factor 1

J Pediatr Gastroenterol Nutr. 2001 Aug;33(2):189-95. doi: 10.1097/00005176-200108000-00018.


Background: Providing partial enteral nutrition (PEN) supplemented with insulinlike growth factor-1 (IGF-1) to parenterally fed piglets increases lactase-phlorizin hydrolase (LPH) activity, but not LPH mRNA. The current aim was to investigate potential mechanisms by which IGF-1 up-regulates LPH activity.

Methods: Newborn piglets (n = 15) received 100% parenteral nutrition (TPN), 80% parenteral nutrition + 20% parenteral nutrition (PEN), or PEN + IGF-1 (1.0 mg. kg-1. d-1) for 7 days. On day 7, [2H3]-leucine was intravenously administered to measure mucosal protein and brush border LPH (BB LPH) synthesis.

Results: Weight gain, nutrient intake, and jejunal weight and length were similar among the treatment groups. Partial enteral nutrition alone increased mucosal weight, villus width and cross-sectional area, LPH activity, mRNA expression, and high mannose LPH precursor (proLPHh) abundance compared with TPN (P<0.05). Insulinlike growth factor-1 further increased mucosal weight, LPH activity, and LPH activity per unit BB LPH approximately twofold over PEN alone (P < 0.05) but did not affect LPH mRNA or the abundance of proLPHh (one of the LPH isoforms) or mature LPH. Isotopic enrichment of [2H3]-leucine in plasma, mucosal protein, and LPH precursors, and the fractional and absolute synthesis rates of mucosal protein and LPH were similar among the treatment groups. Insulinlike growth factor-1 treatment increased total mucosal protein synthesis (60%, P < 0.05) but not LPH synthesis compared with the other two groups.

Conclusions: Because IGF-1 did not affect the fractional synthesis rate of either mucosal protein or LPH, the authors suggest that enteral IGF-1 increases mucosal protein mass and LPH activity by suppressing mucosal proteolytic degradation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn
  • Enteral Nutrition*
  • Insulin-Like Growth Factor I / administration & dosage
  • Insulin-Like Growth Factor I / metabolism
  • Insulin-Like Growth Factor I / pharmacology*
  • Intestinal Mucosa / enzymology*
  • Jejunum / enzymology
  • Lactase-Phlorizin Hydrolase / biosynthesis
  • Lactase-Phlorizin Hydrolase / metabolism*
  • Parenteral Nutrition
  • Protein Biosynthesis*
  • RNA, Messenger / analysis
  • Swine
  • Weight Gain


  • RNA, Messenger
  • Insulin-Like Growth Factor I
  • Lactase-Phlorizin Hydrolase