Postnatal development of lamb intestinal digestive enzymes is not regulated by diet.

Abstract

SUMMARY1. Change in digestive enzyme activities determined biochemically in brushborder membrane vesicles and cytochemically in isolated villi of lamb proximal intestine has been related to diet, intestinal structure and rumen development during the first 10 weeks of postnatal life.2. Lactase activity halved, dipeptidylpeptidase IV activity doubled and aminopeptidase N and alkaline phosphatase activities remained constant during this period of development. Maintaining lambs on a milk replacer diet for 5 weeks after birth had no effect on this pattern of postnatal change in digestive enzyme activities.3. Structural changes accompanying these selective effects on enzyme expression included a halving of villus height and a doubling of villus width. Villus surface area remained unaffected by these changes in height and width of villi. Crypt depth doubled during the first 10 weeks of postnatal life. Maintaining lambs on a milk replacer diet for 5 weeks did not affect this pattern of change in intestinal structure.4. It appears from these results that postnatal decrease in lactase and increase in dipeptidylpeptidase IV activities are not regulated by factors such as diet, rumen development, or changes in intestinal structure. Attention is drawn to differences encountered between these results and a postnatal modification of glucose transport which clearly is dependent on diet.

Molecular characterisation of carbohydrate digestion and absorption in equine small intestine

“…Maltase is expressed all along the equine small intestine. Maltase activity is similar in proximal, mid and distal regions and is extremely high compared with other species; 1 µmol/min/mg protein in the horse (this study) vs. 0.013-0.054 µmol/min/mg wet weight tissue in man (Dahlqvist 1964;Dyer et al 1997b) and 0.014 µmol/min/mg protein in sheep (Shirazi-Beechey et al 1989, 1991b. T h e brush-border membrane lactase is the enzyme responsible for the breakdown of the milk sugar, lactose.…”

Influence of Age on Duodenal Brush Border Membrane and Specific Activities of Brush Border Membrane Enzymes in Wistar Rats.

“…The increase in transporter protein was closely related to increasing site density in the BBM from lamb [27]. With age, the function of absorbing nutrients such as amino acids and glucose in the proximal intestine was impaired in aged mice [9].…”

T1R3 and gustducin in gut sense sugars to regulate expression of Na + -glucose cotransporter 1

“…G␣ gust and T1R3 knockout mice had similar amounts of intestinal SGLT1 protein and Na ϩ -dependent glucose transport when maintained on low-or high-carbohydrate diets. Thus, whereas wild-type animals are known to respond to increased dietary carbohydrate with enhanced SGLT1 expression (4,15), neither G␣ gust nor T1R3 knockouts responded in this way. Morphometric analysis indicated that neither crypt depths nor villus heights differed in the intestines of mice maintained on either a low-or a high-carbohydrate diet, ruling out a trophic effect [see supporting information (SI) Fig.…”

“…Total RNA isolated from intestinal tissue by using the RNeasy Mini Kit with on-column DNase 1 digestion (Qiagen, Crawley, U.K.) was used for cDNA synthesis using Superscript III reverse transcriptase (Invitrogen, Carlsbad, CA) and oligo(dT) [12][13][14][15][16][17][18] primers. cDNA was cleaned up by using the Machery-Nagel Nucleospin extract kit (AB Gene, Epsom, U.K.), and 50 ng of cDNA was used per reaction.…”