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Research Project: Developmental Determinants of Obesity in Infants and Children

Location: Children's Nutrition Research Center

Title: Milk glucosidase activity enables suckled pup starch digestion

item NICHOLS, BUFORD - Children'S Nutrition Research Center (CNRC)
item DIAZ-SOTOMAYOR, MARICELA - Children'S Nutrition Research Center (CNRC)
item AVERY, STEPHEN - Texas Children'S Hospital
item CHACKO, SHAJI - Children'S Nutrition Research Center (CNRC)
item HADSELL, DARRYL - Children'S Nutrition Research Center (CNRC)
item BAKER, SUSAN - State University Of New York (SUNY)
item HAMAKER, BRUCE - Purdue University
item YAN, LI - Purdue University
item LIN, HUI - University Of Idaho
item QUEZADA-CALVILLO, ROBERTO - Children'S Nutrition Research Center (CNRC)

Submitted to: Molecular and Cellular Pediatrics
Publication Type: Review Article
Publication Acceptance Date: 1/8/2016
Publication Date: 2/1/2016
Citation: Nichols, B.L., Diaz-Sotomayor, M., Avery, S.E., Chacko, S.K., Hadsell, D.L., Baker, S.S., Hamaker, B.R., Yan, L.K., Lin, H.M., Quezada-Calvillo, R. 2016. Milk glucosidase activity enables suckled pup starch digestion. Molecular and Cellular Pediatrics. doi:10.1186/s40348-016-0032-z.

Interpretive Summary:

Technical Abstract: Starch requires six enzymes for digestion to free glucose: two amylases (salivary and pancreatic) and four mucosal maltase activities; sucrase-isomaltase and maltase-glucoamylase. All are deficient in suckling rodents. The objective of this study is to test (13)C-starch digestion before weaning by measuring enrichment of blood (13)C-glucose in maltase-glucoamylase-null and wild-type mice. Maltase-glucoamylase gene was ablated at the N-terminal. Dams were fed low (13)C-diet and litters kept on low (13)C-diet. Pups were weaned at 21 days. Digestion was tested at 13 and 25 days by intragastric feeding of amylase predigested (13)C-alpha-limit dextrins. Blood (13)C-glucose enrichment was measured by gas chromatography combustion isotope ratio mass spectrometry (GCRMS) using penta-acetate derivatives. Four hours after feeding, blood (13)C-glucose was enriched by 26×10**3 in null and 18×10**3 in wild-type mice at 13 days and 0.3×10**3 and 0.2×103 at 25 days (vs. fasting p=0.045 and p=0.045). By jejunal enzyme assay, immunohistochemistry, or Western blots, there was no maltase activity or brush border staining with maltase-glucoamylase antibodies at 13 days, but these were fully developed in the wild-type mice by 25 days. In 13-day null mice, luminal contents were stained by maltase-glucoamylase antibodies. Lactating the mammary gland revealed maltase-glucoamylase antibody staining of alveolar cells. Reverse transcription/polymerase chain reaction (RT/PCR) of lactating glands revealed a secreted form of maltase-glucoamylase. (13)C-alpha-limit dextrins were rapidly digested to (13)C-glucose in 13-day mice independent of maltase-glucoamylase genotype or mucosal maltase activity. This experiment demonstrates that a soluble maltase activity is secreted in mouse mother's milk which enables suckling pup starch digestion well before brush border enzyme development. This experiment with (13)C-alpha-limit dextrins needs to be repeated in human breast fed infants.