Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.108 (lactase)
 2,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mucosal disaccharidases and ornithine decarboxylase activities were measured in malnourished, preweaning (19 days), post weaning (24 days) and young adult (37 days) rats. Malnutrition resulted in decreased body weight, intestinal weight, DNA and protein content. Mucosal Prot/DNA ratios were elevated in the ileal segments of the 24 and 37 day rats. Preweaned malnourished rats had significantly enhanced lactase specific activity in both jejunal and ileal segments. Adult malnourished rats showed enhanced jejunal lactase and sucrase activities which were not accompanied by elevated ornithine decarboxylase values. Mucosal sucrase and ornithine decarboxylase specific activities were significantly elevated in the ileal segment of the 24 and 37 day old malnourished rats. Studies of adult rats showed that these increased specific activities were located in the mature enterocytes at the villus tip, and persisted during a 24 h diurnal cycle. DFMO administration for 4 days completely inhibited mucosal ornithine decarboxylase and abolished the rise of ileal sucrase activity. We concluded that the intestinal response to reduced food intake is age related and differs in the jejunum and ileum: ornithine decarboxylase and polyamines are involved in ileal adaptation to malnutrition in postweaned and adult rats.
 ...
PMID:Adaptive response of ileal mucosa to malnutrition in the rat: role of polyamines. 192 51

An experiment was conducted using 16 Holstein male calves from 4 to 21 d of age to compare 1) the effects of an all-milk protein milk replacer (MPR) and a milk replacer with 20% of the protein from soy protein concentrate (SPC) on morphological and enzymic small intestinal variables, and 2) the effects of SPC plus putrescine (SPP) or SPC plus ethylamine (SPE) on intestinal variables. Small intestinal absorption, based on xylose absorption tests, was greater in calves fed MPR than in those fed SPC (P less than 0.01) and was intermediate in SPP- and SPE-fed calves. Small intestinal segments were surgically excised from the proximal and distal jejunum of all calves at 7, 14 and 21 d of age. Villus length tended to be greatest in calves fed MPR, and mitotic index was least in SPC-fed calves (P less than 0.05). Mucosal protein concentration was 46, 41, 44 and 44 micrograms/mg mucosa for calves fed MPR, SPC, SPP and SPE, respectively. The ratio of mucosal protein:RNA was greatest in calves fed MPR, least in those fed SPC at d 7 (P less than 0.01) and d 14 (P less than 0.05), and intermediate in calves fed SPP and SPE. In proximal jejunum, activity of mucosal ornithine decarboxylase (ODC, EC 4.1.1.17; the rate-limiting enzyme in polyamine biosynthesis) in calves fed SPP was less than 50% of that in calves fed MPR, SPC or SPE. The activity of lactase (EC 3.2.1.108) and ODC in distal jejunum was 50% less in calves fed soybean protein than in those fed MPR.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Effects of dietary amines on the small intestine in calves fed soybean protein. 275 10

In adult sparse-fur mutant mice, ornithine transcarbamylase (OTC) activity represents only 14% of the normal values. We studied the development of this activity from birth to adult period and demonstrated that the enzyme deficiency is already fully expressed at birth, in both the liver and the small intestine of mutants. Since OTC catalyzes the conversion of ornithine to citrulline, in the presence of carbamoyl-phosphate, the effect of a disturbed ornithine metabolism on the postnatal development of the small intestine has been evaluated. The normal appearance of sucrase as well as the normal increase of glucoamylase, trehalase, and alkaline phosphatase activities are delayed in sparse-fur mice compared with controls. Moreover, normal adult values are never attained. In contrast, the normal decline of lactase activity is impaired while leucylnaphthylamidase activity is unaffected. Cell proliferation, as evaluated by [3H]thymidine incorporation into DNA and mitotic index, is less active during the 3rd wk of life in mutants. These phenomena are closely associated with a transient weak arginase and ornithine decarboxylase activity in the small intestine. Since arginase catalyzes the conversion of arginine to orthithine, thus ensuring the availability of this substrate for ornithine decarboxylase activity, these results indicate a disturbance of polyamine metabolism in mutant enterocytes with a consequent delay in postnatal differentiation and proliferation. Sparse-fur mutant mouse may therefore represent a useful animal model for evaluating the role of ornithine metabolism in the maturation process of the small intestine.
 ...
PMID:Postnatal maturation of enterocytes in sparse-fur mutant mice. 395 97

Enterocyte growth and differentiation occur simultaneously within the epithelium, but little is known regarding any relationship between these two processes. Four rat models of small intestinal epithelial hypo- and hyperplasia (neonatal ontogeny, fasting/refeeding, hypo-/hyperthyroidism, and bombesin treatment) were used to study the regulation of enterocyte gene expression in relation to epithelial growth state. Mucosal scrapings, as well as crypt and villus cell populations, were subjected to Northern blot analyses using radiolabeled cDNA probes corresponding to lactase, intestinal alkaline phosphatase, villin, ornithine decarboxylase (ODC), and the actin control. In all four models, the hypoplastic (atrophic) condition is characterized by high levels of lactase and low levels of the 3.0-kb intestinal alkaline phosphatase mRNA, whereas under hyperplastic conditions this pattern is reversed. The changes in intestinal alkaline phosphatase and lactase are qualitatively similar along the longitudinal axis of the intestine and are proportional to the degree of hyperplasia, as verified by ODC mRNA levels. Furthermore, the crypt-villus axis of differentiation is maintained regardless of epithelial growth state. In conclusion, the pattern of brush-border enzyme gene expression changes as a function of epithelial growth state, indicating a previously unrecognized degree of plasticity to the state of enterocyte differentiation.
 ...
PMID:Pattern of rat intestinal brush-border enzyme gene expression changes with epithelial growth state. 765 20

The factors regulating the developmental changes in intestinal morphology and enzyme activity during the postnatal period are incompletely understood. Increased ornithine decarboxylase (ODC) and polyamine levels occur in association with increased mucosal growth seen just prior to weaning. The present work examines the effects of the polyamine spermidine, administered exogenously during early postnatal development in the rat, on structural and functional differentiation of the intestine. Young rats were fed 6 mumol of spermidine for either 1 day (P1) or 3 days (P3) prior to sacrifice on postnatal day 10. Control littermates were sacrificed at day 10 (C10) or at day 49 (C49) (postweanling [adult] reference). A loss of most of the well-developed characteristic endosomal complex and supranuclear giant lysosome was observed in the absorptive cells of the ileum and proximal colon in the spermidine-treated groups and was accompanied by a decline in N-acetyl-glucosaminidase activity to adult levels. A precocious appearance of sucrase and NaK ATPase activities was observed in the P1 group and these activities attained adult levels in the P3 group. This premature appearance of sucrase and NaK ATPase activities was associated with a decline in lactase levels. The exogenous administration of spermidine also elicited an increase in mucosal ODC activity.
 ...
PMID:Effect of exogenously administered polyamine on the structural maturation and enzyme ontogeny of the postnatal rat intestine. 839 Mar 4

To evaluate the role of dietary polyamines in maturation of the rat small intestine, spermine was given orally twice daily to suckling pups from day 10 to day 14 postpartum at different doses: 0, 0.2, 0.5, 1, 2.5, and 5 mumol/dose. Compared to saline treated controls, spermine (5 mumol) produced significant increases in mucosal mass parameters (+12 to +57%, P < 0.05), induced prematurely an adult pattern of microvillous enzymes, and enhanced, respectively, by 19- and 3.5-fold (P < 0.01 vs controls) the concentration of the secretory component of p-immunoglobulins in villous and crypt cells. The response of microvillous enzymes (lactase, sucrase, maltase, and aminopeptidase) to spermine was dose-dependent and -specific since oral administration of arginine (5 mumol) or ornithine (5 mumol) was without effect. Intestinal changes were found to be significant (P < 0.05) for doses of spermine exceeding 1 mumol/day, which is in the range of the amount of polyamines provided by solid pellets at weaning (0.4 mumol/g). However, intestinal changes were undetectable at the physiological amounts of polyamines consumed by pups from rat milk during the suckling period (less than 0.3 mumol/day). Consistent with a direct effect of spermine on the intestinal cell, the cytosolic activity of ornithine decarboxylase was depressed by 27-fold (P < 0.005 vs controls) in the jejunum, while inhibition of ornithine decarboxylase by alpha-difluoromethylornithine did markedly decrease but did not suppress the cell response to spermine. Alternately, plasma corticosteronemia, which was virtually absent by day 14 in controls, ranged between 1.4 and 4.6 micrograms/dl in 60% (N = 9) of the spermine-treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Maturation of villus and crypt cell functions in rat small intestine. Role of dietary polyamines. 850 5

Glucagon-like peptide-2 (GLP-2) stimulates small intestinal growth through induction of intestinal epithelial proliferation. To examine the physiology of GLP-2-induced bowel, mice were treated with GLP-2 (2.5 micrograms) or vehicle for 10 days. Small intestinal weight increased to 136 +/- 2% of controls in GLP-2-treated mice, in parallel with 1.4 +/- 0.1- and 1.9 +/- 0.5-fold increments in duodenal RNA and protein content, respectively (P < 0.05-0.001). Similarly, the activities of duodenal maltase, sucrase, lactase, glutamyl transpeptidase, and dipeptidyl-peptidase IV (215 +/- 28% of controls; P < 0.001) were increased by GLP-2. Oral or duodenal administration of glucose or maltose did not reveal any differences in the ability of GLP-2-treated mice to absorb these nutrients, possibly because of decreases in expression of the glucose transporters sodium-dependent glucose transporter-1 (SGLT-1) and GLUT-2. In contrast, absorption of leucine plus triolein was increased after duodenal administration in GLP-2-treated mice (P < 0.01-0.001). Finally, GLP-2 did not alter other markers of intestinal or pancreatic gene expression, including levels of mRNA transcripts for ornithine decarboxylase, multidrug resistance gene, amylase, proglucagon, proinsulin, and prosomatostatin. Thus induction of intestinal growth by GLP-2 in wild-type mice results in a normal-to-increased capacity for nutrient digestion and absorption in vivo.
 ...
PMID:Intestinal function in mice with small bowel growth induced by glucagon-like peptide-2. 922 51