AbstractᅟStarch 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.ObjectiveThe objective of this study is to test 13C-starch digestion before weaning by measuring enrichment of blood 13C-glucose in maltase-glucoamylase-null and wild-type mice.MethodsMaltase-glucoamylase gene was ablated at the N-terminal. Dams were fed low 13C-diet and litters kept on low 13C-diet. Pups were weaned at 21 days. Digestion was tested at 13 and 25 days by intragastric feeding of amylase predigested 13C-α-limit dextrins. Blood 13C-glucose enrichment was measured by gas chromatography combustion isotope ratio mass spectrometry (GCRMS) using penta-acetate derivatives.ResultsFour hours after feeding, blood 13C-glucose was enriched by 26 × 103 in null and 18 × 103 in wild-type mice at 13 days and 0.3 × 103 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.Conclusions(1) 13C-α-limit dextrins were rapidly digested to 13C-glucose in 13-day mice independent of maltase-glucoamylase genotype or mucosal maltase activity. (2) 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. (3) This experiment with 13C-α-limit dextrins needs to be repeated in human breast fed infants.

中文翻译：

---

牛奶葡萄糖苷酶活性使乳幼仔淀粉消化成为可能

Abstractᅟ淀粉需要六种酶来消化以释放葡萄糖：两种淀粉酶（唾液和胰腺）和四种粘膜麦芽糖酶活性；蔗糖酶-异麦芽糖酶和麦芽糖酶-葡糖淀粉酶。所有乳啮齿动物均存在缺陷。目的本研究的目的是通过测量麦芽糖酶-葡糖淀粉酶缺失和野生型小鼠血液 13C-葡萄糖的富集来测试断奶前 13C-淀粉的消化情况。 -终端。母猪喂食低 13C 饮食，而幼仔则采用低 13C 饮食。幼崽在 21 天时断奶。在第 13 天和第 25 天通过胃内喂养淀粉酶预消化的 13C-α-极限糊精来测试消化。使用五乙酸衍生物通过气相色谱燃烧同位素比质谱法 (GCRMS) 测量血液 13C-葡萄糖富集。 结果 进食后四小时，在第 13 天和 0.3 × 103 和 0.2 × 103 在第 25 天（相对于禁食 p = 0.045 和 p = 0.045），血液 13C-葡萄糖在空小鼠和 18 × 103 的空小鼠中富集。通过空肠酶测定、免疫组织化学或蛋白质印迹，在 13 天时没有麦芽糖酶活性或麦芽糖酶-葡糖淀粉酶抗体的刷状缘染色，但这些在 25 天时在野生型小鼠中完全发育。在 13 天的空小鼠中，管腔内容物被麦芽糖酶-葡糖淀粉酶抗体染色。乳腺泌乳揭示了肺泡细胞的麦芽糖酶-葡糖淀粉酶抗体染色。泌乳腺体的逆转录/聚合酶链反应 (RT/PCR) 揭示了麦芽糖酶-葡糖淀粉酶的分泌形式。结论 (1) 13C-α-极限糊精在 13 天小鼠体内迅速消化为 13C-葡萄糖，而不受麦芽糖酶-葡糖淀粉酶基因型或粘膜麦芽糖酶活性的影响。(2) 本实验表明，小鼠母乳中分泌的可溶性麦芽糖酶活性能够在刷状缘酶发育之前很好地消化幼崽淀粉。(3) 需要在人类母乳喂养的婴儿中重复使用 13C-α-极限糊精的实验。