Stimulation of Intestinal Lactase Activities in Rat Small In testine by Fasting and Its Mechanism

Song, In Sung; Kim, chung Yong; Lee, Kook Lae; Lim, Seon Hee

Abstract

BACKGROUND/AIMS: To investigate the influence of fasting upon the activity and the gene expression of the intestinal lactase, and to evaluate the effects of systemic hormones on the activity of intestinal lactase after fasting, we had done this experiment.
METHODS
Forty adult Wistar rats with 200 gm of average weight were divided into 4 groups, of which three groups vvere starved for 1(Group A), 3(Group B), 5 days(Group C) before sacrifice, and the other was a contol group. Their blood was obtained by cardiac punture before sacrifice. And their small intestines were obtained and divided into 3 equal length. Mucosal homogenates were prepared for measurement of specific activities of disaccharidases. Total RNA was extracted for determination of the amount of lactase mRNA by northern and slot hybridization. The serum thyroxine(T4) and triiodothyronine levels were assayed by RIA,
RESULTS
Fasting caused a significant increase in lactase activity(p<0.05), but the amount of the corresponding mRNA was not significantly different(p<0.05). Sucrase activity in the brush border membranes by starvation was slightly decreased, which was not statistically significant. T and T4 were significantly decreased after starvatic>n(p<0.05).
CONCLUSIONS
These results indicate that intestinal hydrolases respond non-coordinately to food deprivation. In addition, the thyroid status of the animals has an influence on the aclaptation of intestinal lactase to starvation. And these adaptive processes seem to be partly controlled at a post-transcriptional level.