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


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.


CONCLUSIONS
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.
The University of Shizuoka, Graduate School of Nutritional and Environmental Sciences and Global COE, Shizuoka, Japan.
Kazuki
K
Mochizuki
Makiko
M
Igawa-Tada
Sachiko
S
Takase
Toshinao
T
Goda
D000818:Animals; D004032:Diet; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004041:Dietary Fats / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D005690:Galactose / Q000378:metabolism*; D006031:Glycosylation; D007583:Jejunum / Q000187:drug effects*; D008297:Male; D009237:N-Acetyllactosamine Synthase / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013394:Sucrase-Isomaltase Complex / Q000378:metabolism*
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D012333:RNA, Messenger; D009237:N-Acetyllactosamine Synthase; D013394:Sucrase-Isomaltase Complex; D005690:Galactose