title: Susceptibility of lactase to luminal proteases in developing rat intestine.
abstract: BACKGROUND
  Postnatal development of rat intestine is associated with a decline in brush-border lactase activity. This phenomenon is similar to the adulthood hypolactasia in humans. However, the mechanism underlying this process is not understood.
  
  
  METHODS
  The effect of luminal proteases from adult rat intestine on the intestinal lactase activity in animals aged 7, 14, 21 and 30 days was studied in in vitro experiments. Lactase levels were estimated using enzyme assays and Western blot analysis.
  
  
  RESULTS
  Incubation of purified brush borders with increasing concentrations of luminal proteases reduced the lactase activity in intestine of 7-day-old rats, but not in that of adult animals. Western blot analysis revealed low signal of the 220-kDa lactase protein in 7-day-old animals, but not that of older weaned animals.
  
  
  CONCLUSIONS
  Our findings suggest that luminal proteases may be responsible for the maturational decline in intestinal lactase activity.
authors.affiliation: Department of Experimental Medicine and Biotechnology, Postgraduate Institute of Medical Education and Research, Chandigarh 160 012, India.
authors.forename: Kamaljit
authors.initials: K
authors.lastname: Kaur
authors.forename: Safrun
authors.initials: S
authors.lastname: Mahmood
authors.forename: Akhtar
authors.initials: A
authors.lastname: Mahmood
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D010450:Endopeptidases / Q000494:pharmacology*; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects* / Q000648:ultrastructure; D043322:Lactase / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
chemical_list: D043322:Lactase; D010450:Endopeptidases