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Gene Review

Lct  -  lactase

Rattus norvegicus

Synonyms: Lactase-glycosylceramidase, Lactase-phlorizin hydrolase, Lph
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Disease relevance of Lct


Psychiatry related information on Lct

  • A general hypothesis is proposed in order to clear up partly the mechanism involved in the stimulation of lactase activity by food deprivation in the adult rat [6].
  • In other words, the fundamental pattern of significant depression of lactase expression occurred relatively independent of dietary modification [7].

High impact information on Lct

  • A gene 'pill' associated with highly efficient and stable gene expression might be a practical and cost-effective strategy for even relatively mild disorders, such as lactase deficiency [8].
  • In contrast, mutations E1750D and E1750G resulted in total loss of lactase and cellobiose activities, leaving only low ONP-glc and ONP-gal hydrolase activities detectable [9].
  • This study provides the first evidence that rat LPH has its major catalytic site at E1750, representing all of the lactase and the majority of the phlorizin hydrolase activity [9].
  • BACKGROUND/AIMS: Developmental changes of lactase activity along the proximal-to-distal axis of the small intestine are poorly understood [10].
  • After 28 days, zones of reduced lactase expression were found in the duodenum and terminal ileum [10].

Chemical compound and disease context of Lct

  • Although ethanol had been withdrawn at birth, pups issued from ethanol-treated mothers showed at 5 and 10 d postpartum decreased values of body weight, jejunal and ileal weights, and intestinal DNA concentration per unit of length, as well as lower specific and total activities in lactase and maltase, compared with controls [11].
  • Adrenalectomy prevented the oral effect of spermine on sucrase- and maltase-specific activity but not on lactase-specific activity [12].
  • The effects of bilateral adrenalectomy and subsequent force-feeding of L-tryptophan (30 mg/100 g body weight) on the activity of disaccharidases (lactase, sucrase, and maltase) in the jejunum and ileum were investigated [13].
  • Results from these studies indicate that the birth weights of newborn rats exposed to cortisone in utero were significantly reduced; sucrase activity was prematurely induced and specific activities of lactase and maltase were enhanced in the intestines of the cortisone-treated newborns as contrasted with control animals [14].
  • The study revealed that the activities of brush border sucrase, lactase and leucine aminopeptidase were stimulated only at high doses, viz 70 mg/kg (180 mumol/kg) body weight and above, whereas the activity of alkaline phosphate was depressed at comparatively low dose (17.5 mg/kg; 45 mumol/kg body weight) [15].

Biological context of Lct


Anatomical context of Lct

  • Analysis of the regional distribution of lactase mRNA along the small intestine at 14 days revealed that mRNA was high in the proximal three regions, but was dramatically lower in the distal regions [16].
  • Membrane vesicles from developing (day 14-21) and adult Sprague-Dawley rats were enriched to a similar degree in brush border membrane marker enzyme activities (sucrase or lactase) compared with homogenate [19].
  • Demonstration of a difference in expression of maximal lactase and sucrase activity along the villus in the adult rat jejunum [2].
  • At weaning, the amount of lactase messenger RNA dropped specifically in the distal ileum [20].
  • The intestine in continuity showed precocious appearance of active sucrase and accumulation along with maltase to greater than control levels, accompanied by a normal coincident decline in lactase activity and enterocyte life-span [21].

Associations of Lct with chemical compounds


Physical interactions of Lct


Regulatory relationships of Lct


Other interactions of Lct

  • To test the above hypotheses we employed phlorizin (as an inhibitor of SGLT1) and N-(n-butyl)-deoxygalactonojirimycin (as an inhibitor of the lactase domain of LPH) in a rat everted-jejunal sac model [22].
  • TNF-alpha had no effect on sucrase and maltase specific activity, but a slight augmentation of lactase specific activity was detected in the jejunum [28].
  • IL-6 elicited sucrase and increased maltase specific activity in the whole small intestine, but lactase specific activity was not affected [28].
  • Intraperitoneal (i.p.) injection of IL-1 beta increased the specific activity of sucrase in whole small intestine, whereas the specific activities of maltase and lactase were significantly enhanced only in the jejunum [28].
  • The effect of prolactin on thymidine incorporation and tissue alkaline phosphatase, maltase and lactase activity was studied on jejunal explants from fetal, newborn and 2 week-old rats [29].

Analytical, diagnostic and therapeutic context of Lct


  1. Thyroxine-evoked decrease of jejunal lactase activity in adult rats. Celano, P., Jumawan, J., Koldovsky, O. Gastroenterology (1977) [Pubmed]
  2. Demonstration of a difference in expression of maximal lactase and sucrase activity along the villus in the adult rat jejunum. Boyle, J.T., Celano, P., Koldovský, O. Gastroenterology (1980) [Pubmed]
  3. Saccharomyces boulardii upgrades cellular adaptation after proximal enterectomy in rats. Buts, J.P., De Keyser, N., Marandi, S., Hermans, D., Sokal, E.M., Chae, Y.H., Lambotte, L., Chanteux, H., Tulkens, P.M. Gut (1999) [Pubmed]
  4. Intestinal disaccharidases in malnourished infant rats. Jambunathan, L.R., Neuhoff, D., Younoszai, M.K. Am. J. Clin. Nutr. (1981) [Pubmed]
  5. Effect of O-sulphate groups in lactose and N-acetylneuraminyl-lactose on their enzymic hydrolysis. Mian, N., Anderson, C.E., Kent, P.W. Biochem. J. (1979) [Pubmed]
  6. Stimulation of lactase synthesis induced by starvation in the jejunum of adult rat. Nsi-Emvo, E., Raul, F. Enzyme (1984) [Pubmed]
  7. Dietary control of lactase expression in the weaning rat. Sakuma, K., Watanabe, Y., Kurahashi, Y. Biomed. Environ. Sci. (1996) [Pubmed]
  8. Peroral gene therapy of lactose intolerance using an adeno-associated virus vector. During, M.J., Xu, R., Young, D., Kaplitt, M.G., Sherwin, R.S., Leone, P. Nat. Med. (1998) [Pubmed]
  9. Verification of the lactase site of rat lactase-phlorizin hydrolase by site-directed mutagenesis. Neele, A.M., Einerhand, A.W., Dekker, J., Büller, H.A., Freund, J.N., Verhave, M., Grand, R.J., Montgomery, R.K. Gastroenterology (1995) [Pubmed]
  10. Restriction of lactase gene expression along the proximal-to-distal axis of rat small intestine occurs during postnatal development. Rings, E.H., Krasinski, S.D., van Beers, E.H., Moorman, A.F., Dekker, J., Montgomery, R.K., Grand, R.J., Büller, H.A. Gastroenterology (1994) [Pubmed]
  11. Prenatal exposure to ethanol in rats: effects on postnatal maturation of the small intestine and liver. Buts, J.P., Sokal, E.M., Van Hoof, F. Pediatr. Res. (1992) [Pubmed]
  12. Intestinal development in suckling rats: direct or indirect spermine action? Kaouass, M., Deloyer, P., Dandrifosse, G. Digestion (1994) [Pubmed]
  13. Effect of adrenalectomy and tryptophan force-feeding on the activity of intestinal disaccharidases in adult rats. Majumdar, A.P. Scand. J. Gastroenterol. (1980) [Pubmed]
  14. Development of gastrointestinal mucosal barrier. VII. In utero maturation of microvillus surface by cortisone. Pang, K.Y., Newman, A.P., Udall, J.N., Walker, W.A. Am. J. Physiol. (1985) [Pubmed]
  15. Effect of various doses of medroxyprogesterone acetate on intestinal functions in rats. Nagpaul, J.P., Kaushal, M., Majumdar, S., Mahmood, A. Indian journal of gastroenterology : official journal of the Indian Society of Gastroenterology. (1990) [Pubmed]
  16. Coordinate expression of lactase-phlorizin hydrolase mRNA and enzyme levels in rat intestine during development. Büller, H.A., Kothe, M.J., Goldman, D.A., Grubman, S.A., Sasak, W.V., Matsudaira, P.T., Montgomery, R.K., Grand, R.J. J. Biol. Chem. (1990) [Pubmed]
  17. Regulation of intestine-specific spatiotemporal expression by the rat lactase promoter. Lee, S.Y., Wang, Z., Lin, C.K., Contag, C.H., Olds, L.C., Cooper, A.D., Sibley, E. J. Biol. Chem. (2002) [Pubmed]
  18. Ontogeny of intestinal safety factors: lactase capacities and lactose loads. O'Connor, T.P., Diamond, J. Am. J. Physiol. (1999) [Pubmed]
  19. Ontogeny of bile acid transport in brush border membrane vesicles from rat ileum. Moyer, M.S., Heubi, J.E., Goodrich, A.L., Balistreri, W.F., Suchy, F.J. Gastroenterology (1986) [Pubmed]
  20. Lactase expression is controlled differently in the jejunum and ileum during development in rats. Freund, J.N., Duluc, I., Raul, F. Gastroenterology (1991) [Pubmed]
  21. Delayed ontogenic development in the bypassed ileum of the infant rat. Tsuboi, K.K., Kwong, L.K., Ford, W.D., Colby, T., Sunshine, P. Gastroenterology (1981) [Pubmed]
  22. Absorption of quercetin-3-glucoside and quercetin-4'-glucoside in the rat small intestine: the role of lactase phlorizin hydrolase and the sodium-dependent glucose transporter. Day, A.J., Gee, J.M., DuPont, M.S., Johnson, I.T., Williamson, G. Biochem. Pharmacol. (2003) [Pubmed]
  23. Posttranslational cleavage of rat intestinal lactase occurs at the luminal side of the brush border membrane. Yeh, K.Y., Yeh, M., Pan, P.C., Holt, P.R. Gastroenterology (1991) [Pubmed]
  24. Effects of dietary lipids on recovery from mucosal injury. Vanderhoof, J.A., Park, J.H., Mohammadpour, H., Blackwood, D. Gastroenterology (1990) [Pubmed]
  25. Biochemistry and immunochemistry of membrane-bound enzymes. Kraml, J., Lojda, Z. Acta Universitatis Carolinae. Medica. Monographia. (1977) [Pubmed]
  26. Basement membrane components are potent promoters of rat intestinal epithelial cell differentiation in vitro. Hahn, U., Stallmach, A., Hahn, E.G., Riecken, E.O. Gastroenterology (1990) [Pubmed]
  27. Diet fat and oral insulin-like growth factor influence the membrane fatty acid composition of suckling rat small intestine. Kit, S., Thomson, A.B., Clandinin, M.T. J. Pediatr. Gastroenterol. Nutr. (1999) [Pubmed]
  28. Role of interleukin-1 beta, interleukin-6, and TNF-alpha in intestinal maturation induced by dietary spermine in rats. Kaouass, M., Deloyer, P., Gouders, I., Peulen, O., Dandrifosse, G. Endocrine (1997) [Pubmed]
  29. A possible role of prolactin on growth and maturation of the gut during development in the rat. Bujanover, Y., Wollman, Y., Reif, S., Golander, A. Journal of pediatric endocrinology & metabolism : JPEM. (2002) [Pubmed]
  30. Ontogenic timing mechanism initiates the expression of rat intestinal sucrase activity. Yeh, K.Y., Holt, P.R. Gastroenterology (1986) [Pubmed]
  31. Lactase gene expression during early development of rat small intestine. Rings, E.H., de Boer, P.A., Moorman, A.F., van Beers, E.H., Dekker, J., Montgomery, R.K., Grand, R.J., Büller, H.A. Gastroenterology (1992) [Pubmed]
  32. Structural and enzymatic changes during colonic maturation in the fetal and suckling rat. Colony, P.C., Kois, J.M., Peiffer, L.P. Gastroenterology (1989) [Pubmed]
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