Modification of rat caecal microbial biotransformation activities by dietary saccharin

Toxicology. 1985 Aug;36(2-3):253-62. doi: 10.1016/0300-483x(85)90058-7.


Male Sprague-Dawley rats were fed a purified fibre-free diet containing 5% (w/w) sodium saccharin for 4 weeks or 20 weeks and changes in caecal bacterial numbers and enzyme activities (endogenous ammonia production, beta-glucosidase, beta-glucuronidase, nitrate reductase, nitroreductase, aryl sulphatase) determined in vitro. Saccharin treatment gave marked caecal enlargement but had no effect on bacterial concentration at either treatment period, and significantly decreased beta-glucuronidase, nitrate reductase and sulphatase activities/g caecal contents. The incubation of a suspension of caecal contents from control rats with saccharin (75 mM) in vitro inhibited beta-glucuronidase and nitrate reductase activities, and ammonia production from endogenous substrates. Such changes may decrease the rate of formation of toxic bacterial products in the hindgut.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ammonia / metabolism
  • Animals
  • Bacteria / drug effects*
  • Bacteria / metabolism
  • Biotransformation
  • Cecum / drug effects
  • Cecum / microbiology*
  • Glucuronidase / analysis
  • Male
  • Nitrate Reductase
  • Nitrate Reductases / analysis
  • Nitroreductases
  • Oxidoreductases / analysis
  • Rats
  • Rats, Inbred Strains
  • Saccharin / toxicity*


  • Ammonia
  • Oxidoreductases
  • Nitrate Reductases
  • Nitroreductases
  • Nitrate Reductase
  • Glucuronidase
  • Saccharin