Oral IGF-I Alters the Posttranslational Processing but Not the Activity of Lactase-Phlorizin Hydrolase in Formula-Fed Neonatal Pigs

• Published in: The Journal of nutrition Vol. 131; no. 9; pp. 2235 - 2241
• Main Authors: Burrin, Douglas G., Stoll, Barbara, Fan, Ming Z., Dudley, Mary A., Donovan, Sharon M., Reeds, Peter J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Bethesda, MD Elsevier Inc 01.09.2001; American Society for Nutritional Sciences; American Institute of Nutrition
• Subjects: Administration, Oral; Amino Acids - blood; Amino Acids - metabolism; Animal Feed; animal models; Animals; Animals, Newborn - blood; Animals, Newborn - metabolism; beta-Galactosidase - metabolism; Biological and medical sciences; cell proliferation; Cells; dietary supplements; disaccharidase; DNA; dose response; enzyme activity; Enzyme Precursors - metabolism; Feeding. Feeding behavior; Food, Formulated; free amino acids; Fundamental and applied biological sciences. Psychology; growth factor; Hogs; human nutrition; ileum; insulin-like growth factor I; Insulin-Like Growth Factor I - administration & dosage; Insulin-Like Growth Factor I - metabolism; Insulin-Like Growth Factor I - pharmacology; intestinal mucosa; Intestinal Mucosa - metabolism; Intestines - anatomy & histology; jejunum; Kinetics; Lactase; Lactase-Phlorizin Hydrolase - metabolism; microvilli; Microvilli - enzymology; neonates; nutrient transport; Nutrition; nutrition physiology; O-glycoside hydrolases; oral administration; Organ Size - drug effects; Osmolar Concentration; pigs; post-translational modification; protein content; protein degradation; Protein Processing, Post-Translational - drug effects; protein synthesis; Proteins; Proteins - metabolism; Swine; tissue weight; Vertebrates: anatomy and physiology, studies on body, several organs or systems; growth factor; BB-LPH; pro-LPH; pigs; IGF-I; cell proliferation; LPH; protein synthesis; disaccharidase; protein degradation; IRMA; Human; Cell proliferation; Enzyme; Lactase; Glycosylceramidase; Oral administration; Insulin like growth factor 1; Pig; Vertebrata; Mammalia; Newborn; Protein synthesis; Glycosidases; Hydrolases; Artiodactyla; O-Glycosidases; Ungulata
• ISSN: 0022-3166; 1541-6100
• DOI: 10.1093/jn/131.9.2235

To determine the cellular mechanism whereby oral insulin-like growth factor I (IGF-I) increases intestinal lactase-phlorizin hydrolase (LPH) activity, we studied 2-d-old pigs fed cow's milk formula (control, n = 5), formula + low IGF-I (0.5 mg/L; n = 6) or formula + high IGF-I (12.0 mg/L, n = 6) for 15 d. On d 15, intestinal protein synthesis and lactase processing were measured in vivo in fed pigs using a 6-h intravenous, overlapping infusion of multiple stable isotopes (2H3-Leu,13C1-Leu,13C1-Phe,2H5-Phe,13C6-Phe and 13C9-Phe). Morphometry and cell proliferation also were measured in the jejunum and ileum. Neither dose of IGF-I affected the masses of wet tissue, protein or DNA, or the villus height, cell proliferation or LPH-specific activity. Oral IGF-I decreased the synthesis and abundance of prolactase-phlorizin hydrolase (pro-LPH), but increased brush-border (BB)-LPH synthesis in the ileum. The BB-LPH processing efficiency was twofold to threefold greater in IGF-fed than in control pigs. In all pigs, villus height and the total mucosal and specific activity of LPH activity were greater in the ileum than in the jejunum, yet the synthesis of BB-LPH were significantly lower in the ileum than in the jejunum. We conclude that oral IGF-I increases the processing efficiency of pro-LPH to BB-LPH but does not affect LPH activity. Moreover, the posttranslational processing of BB-LPH is markedly lower in the ileum than in the jejunum. J. Nutr. 131: 2235–2241, 2001.