Feeding rats a high fat/carbohydrate ratio diet reduces jejunal S/I activity ratio and unsialylated galactose on glycosylated chain of S-I complex

Life Sci. 2010 Mar 27;86(13-14):524-31. doi: 10.1016/j.lfs.2010.02.011. Epub 2010 Feb 14.

Abstract

Aims: We examined whether decreasing jejunal sucrase/isomaltase (S/I) activity ratio by feeding rats a high fat/carbohydrate ratio diet is regulated by changing glycosylated chains on the S-I complex.

Main methods: Jejunal activities of sucrase, isomaltase and beta-1,4-galactosyltransferase were examined in rats fed a high fat/carbohydrate or a low fat/carbohydrate ratio diet. The amount of galactose and mannose in the glycosylated chain on the S-I complex in rats fed both diets was determined using RCA(120) and Con A lectins, respectively. The effects of reducing unsialylated galactose from the glycosylated chain on the S-I complex were assessed by determining sucrase activity in purified S-I complex treated with beta-galactosidase.

Key findings and significance: Feeding rats a high fat/carbohydrate ratio diet reduced jejunal S/I activity ratio in mucosal homogenates and purified fractions. The level of unsialylated galactose in glycosylated chains on the S-I complex was reduced by feeding rats a high fat/carbohydrate ratio diet. The form with reduced levels of unsialylated galactose had lower sucrase activity than that with more unsialylated galactose. The reduction of galactose on the S-I complex by beta-galactosidase in vitro reduced sucrase activity. Feeding rats a high fat/carbohydrate ratio diet also reduced jejunal beta-1,4-galactosyltransferase activity. Taken together, decreasing the S/I activity ratio by feeding rats a high fat/carbohydrate diet is associated with the reduction of unsialylated galactose on the glycosylated chain of the S-I complex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Diet*
  • Dietary Carbohydrates / pharmacology*
  • Dietary Fats / pharmacology*
  • Electrophoresis, Polyacrylamide Gel
  • Galactose / metabolism*
  • Glycosylation
  • Jejunum / drug effects*
  • Male
  • N-Acetyllactosamine Synthase / genetics
  • N-Acetyllactosamine Synthase / metabolism
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Sucrase-Isomaltase Complex / metabolism*

Substances

  • Dietary Carbohydrates
  • Dietary Fats
  • RNA, Messenger
  • N-Acetyllactosamine Synthase
  • Sucrase-Isomaltase Complex
  • Galactose