Chromatin structure and transcription activity during maturation of intestinal epithelial cells.
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Animals↗
Biomedical subjects
F Raul
Publications and source records attributed to F Raul.
Changes in chromatin structure and transcription activity by starvation and dietary sucrose in mature and immature intestinal epithelial cells of the rat.
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Animals↗
Dietary sugar promotes gene activation in intestinal cell chromatin of adult rats.
The effect of dietary sucrose on transcription activity of chromatin from intestinal cells of adult rats was investigated. Chromatin-bound RNA polymerase II activity was significantly enhanced after feeding sucrose to rats. RNA polymerase II transcribes the genes coding for pre-messenger RNA. The results indicate that feeding of sucrose increased the synthesis of pre-messenger RNA molecules coding for specific proteins which are involved in the adaptive processes of sucrose hydrolysis in intestinal cells.
Animals↗
Effects of wheat bran on the exocrine pancreas and the small intestinal mucosa in the dog.
Five Beagle dogs, equipped with duodenal and gastric fistulae, were fed a standard diet before receiving the same diet supplemented with wheat bran for 1 month. Pancreatic secretory investigations performed in conscious animals before and 1 month after bran administration showed a significant parallel increase in the flow rate of pancreatic secretion and the outputs of bicarbonate and amylase both in basal and secretin-stimulated conditions. The outputs of protein and chymotrypsin increased only in unstimulated secretions, while the output of lipase was strongly reduced in response to secretin. However, the small intestinal mucosa was not affected by bran administration. Dietary fiber did not alter the height of the villi or the activity of sucrase, maltase and aminopeptidase in mucosal homogenates or isolated brush border membranes from intestinal biopsies. These data suggest that wheat bran supplemented to the standard diet affects the exocrine pancreatic secretion but not intestinal enzyme activities involved in the absorption of carbohydrates and proteins in the dog.
Amylases↗
Stimulation of disaccharidase activities in the jejunal brush border membrane of adult rat by total parenteral nutrition. Effects of thyroid hormones.
This study examined the morphological and functional adaptations occurring in the jejunum of adult rats fed totally by parenteral nutrition during a 4-day period. Comparison was made with sham-operated animals receiving orally a similar isocaloric diet. The intravenously fed rats exhibited a 20% shortening of the villus height. The specific activity of aminopeptidase showed remarkable stability in all conditions. A major stimulation (2.5-fold) was measured for lactase-specific activity. Daily administration of thyroxine completely inhibited the rise of lactase activity. Thyroidectomy caused a significant increase of lactase activity in the orally fed controls, but did not exert any synergistic effect with parenteral nutrition on intestinal enzyme activities. In our experimental conditions intravenous feeding led to a 3-fold decrease in the concentration of thyroid hormones detected in the serum. The results show that total parenteral nutrition leads to a stimulation of the specific activity of brush border lactase in the intestine of adult rat which might be related to the level of thyroid hormones.
Aminopeptidases↗
Stimulation of lactase synthesis induced by starvation in the jejunum of adult rat.
The effects of actinomycin D and of cycloheximide administration have been investigated on the enzyme activities of the jejunal brush border membrane in adult rats after a 48-hour period of starvation. The modifications in the protein and enzyme patterns of the brush border membrane and the incorporation of radiolabelled amino acid in the protein band corresponding to lactase have been studied in the nourished and in the starved animal. The results show that actinomycin D administration did not modify the stimulation of lactase activity caused by starvation whereas cycloheximide completely inhibited this process. The stimulation of lactase activity, in the starved animal, is related to a quantitative increase of the corresponding protein band and with enhanced incorporation of L-[3H]valine in this protein band after separation of brush border proteins by gel electrophoresis. It is concluded that the stimulation of lactase activity observed during starvation is the consequence of de novo synthesis of lactase molecules and that this process is regulated at a translational level. A general hypothesis is proposed in order to clear up partly the mechanism involved in the stimulation of lactase activity by food deprivation in the adult rat.
Animals↗
Stimulation of intestinal chromatin template activity by dietary carbohydrates in adult rats.
Oral administration of a 70% solution of sucrose to starved adult rats resulted 1 h after feeding in a 3.5-fold stimulation of intestinal chromatin template activity assayed in vitro using E. coli RNA polymerase. A similar stimulatory effect was observed with fructose, whereas glucose exhibited a weaker effect, indicating that the nature of the ingested carbohydrate may have a direct effect on the extent of intestinal chromatin template activation.
Animals↗
Modulation of RNA polymerase activities in the intestine of adult rats by dietary sucrose.
The effect of sucrose feeding on endogenous intestinal RNA polymerase activities and on chromatin structure was studied in rats. Adult rats were given a 70% sucrose solution for 15 hours following a 48-hour starvation period. Comparison was made with rats starved for 63 hours and with ad libitum nourished animals. Chromatin-bound RNA polymerase I activity was significantly reduced by starvation. Sucrose feeding provoked a significant rise in the activity, but the level found in the nourished rats was not reached. The free poly[d(A-T)]-dependent RNA polymerase I activity of the sucrose-fed rats exceeded that of the starved and the nourished animals. Chromatin-bound RNA polymerase II activity was enhanced most markedly by sucrose feeding. The balance between the chromatin-bound and free enzymes was shifted towards the chromatin-bound state when compared to the starved and nourished rats. Starvation caused a reduction in the size of oligonucleosomes but sucrose feeding restored almost entirely the original pattern obtained in the nourished animals. These results reflect modifications in the structure of chromatin after sucrose feeding. The present report demonstrates that the adaptive processes triggered in the intestine by dietary sucrose are associated with changes in gene expression.
Animals↗
Lactase activity is under hormonal control in the intestine of adult rat.
In the adult rat, starvation during 48 hours led to a three fold increase of lactase specific activity in the intestinal brush border membranes. Thyroxine injection during the three days before death (0.5 micrograms/g daily) inhibited the stimulation of lactase activity induced by starvation without modifying sucrase activity whereas hydrocortisone injections (25 micrograms/g daily) or thyroidectomy did not modify the stimulatory effect of starvation on lactase activity. These results suggests a specific hormonal control of intestinal lactase activity in the rat.
Animals↗
Effect of chronic alcohol administration on the exocrine pancreas after jejunoileal bypass in the rat.
To determine whether intestinal bypass operation and alcohol administration exerted a synergistic effect on pancreatic enzyme composition and morphology, adult rats were submitted either to a sham-operation or to a 90 per cent jejunoileal bypass. Two weeks after the operation, the rats received a 15 per cent solution of ethanol in drinking fluid during a period of four weeks while controls received water. In sham-operated animals, alcohol had no effect on pancreatic weight or its total content in protein and amylase. The general structural and ultrastructural aspect remained unchanged except for the presence of a few mixed acinar-islet cells. Bypass operation alone induced a significant decrease in amylase content while the population of zymogen granules was reduced. Parallely, lipid droplets deposited within acinar cells. Alcohol administered in bypassed animals exerted a synergistic effect on fat accumulation in pancreatic acinar cells but had no effect on other biochemical and morphological parameters.
Amylases↗
Organ culture of suckling rat intestine: comparative study of various hormones on brush border enzymes.
Jejunal mucosa of 6 d-old rats were cultured for 24 and 48 h in the presence of thyroxine, insulin, pentagastrin, glucagon, epidermal growth factor (EGF) or dibutyryl-A-3:5-MP cyclic with or without dexamethasone (DX). The enzymes were assayed on the purified brush borders. The various agents added alone to the basic culture medium had no effect with the exception of DX on the levels of enzyme activities. Dexamethasone alone induced sucrase, stimulated maltase, and protected other brush border enzyme activities (aminopeptidase, lactase, and alkaline phosphatase). When added to DX-supplemented medium, only the following factors modified the levels of enzymatic activities observed with DX alone. Insulin (10(-6) M) increased maltase, alkaline phosphatase, and lactase activity to a greater extent than DX at 24 h culture, the effect being maintained at 48 h on alkaline phosphatase only. At 48 h culture, both EGF (10(-8) M) and dbcAMP (10(-3) M) decreased DX-induced sucrase activity. The latter agent also depressed DX-stimulated aminopeptidase activity.
Alkaline Phosphatase↗
Effects of prolonged alcohol administration and a high carbohydrate-low protein diet on the activities of the jejunal brush border enzymes in the rat.
The effects of prolonged alcohol administration were studied on the brush border enzyme activities of the jejunum in rats receiving either a normal laboratory diet or a high carbohydrate-low protein for several weeks. Alcohol (15%) given in association with the normal diet provoked a stimulation of sucrase, maltase, and lactase activities after four weeks, but no significant modification in aminopeptidase activity. These results obtained for the disaccharidases were very similar to those observed with the high carbohydrate-low protein diet given without alcohol, although major differences were obvious in the timing of enzyme stimulation. In contrast, this dietary condition initiated a drop in aminopeptidase activity. When alcohol was given in association with the high carbohydrate-low protein diet, no modification in aminopeptidase activity was detected and the stimulation for the disaccharidase activities was similar to that observed with the high carbohydrate-low protein diet given alone. The present results suggest that the mechanisms involved in the stimulation of brush border disaccharidase activities were different for alcohol and for the high carbohydrate-low protein diet.
Animals↗
Effect of chronic alcohol administration on liver morphology and on brush border membrane enzymes after jejunoileal bypass operation in rat.
To determine whether jejunoileal bypass operation and alcohol administration exerted a synergistic effect on the activities of brush border membrane enzymes and on liver morphology, adult rats where submitted either to sham operation or to jejunoileal bypass operation. 2 weeks after operation the rats received a 15% solution of ethanol during a period of 4 weeks, controls received water. In the sham-operated rats, alcohol provoked stimulation of the disaccharidase activities in the proximal jejunum but had no effect on these activities in the ileum. Bypass operation alone induced a significant increase in sucrase activity in the functioning ileum but had no effect on the jejunal disaccharidase activities. Alcohol administered after bypass provoked a further increase in ileal brush border sucrase activity. The increase of the brush border enzyme specific activities in the excluded loop resulted from the important protein loss observed in this segment. Alcohol alone or bypass operation by itself had little effect on liver morphology. In contrast, when associated they induced extensive accumulation of fat droplets in the hepatocytes. Since alcohol is frequently associated with the diet in man, alcohol should be considered as an important contributing factor to intestinal enzyme adaptation and liver dysfunction after jejunoileal bypass operation.
Aminopeptidases↗
Modifications of brush border enzyme activities during starvation in the jejunum and ileum of adult rats.
Aminopeptidase, lactase and sucrase activities have been followed during 5 days in the jejunum and in the ileum of starved adult rats. Enzyme activities have been determined in the mucosal homogenates as well as in the purified brush border membranes and expressed as activities per intestinal length (segmental activities) or as activities per milligram of protein (specific activities). The segmental and specific activity of aminopeptidase was increased in the ileum during the first 2 days of starvation, suggesting that aminopeptidase may have during the first days of starvation a conservative role by preventing an important loss of tissue protein. In all conditions, lactase activity was strikingly enhanced by starvation whereas sucrase activity showed no changes or decreased activity. Lactase stimulation was initiated during the first 24 h of starvation reaching its maximum after 2 days. The various experimental conditions leading to a specific or to a nonspecific stimulation of intestinal lactase activity have been discussed.
Animals↗
[Is stimulation of intestinal sucrase activity by dietary sucrose dependent on RNA synthesis in adult rats? (author's transl)].
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Animals↗
[Death caused by cirrhosis 8 years after jejunoileal bypass].
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Female↗
Organogenetic potentialities of rat intestinal epithelioid cell culture.
The aim of the present study was to investigate the mesenchymal influence on cultured epithelioid cells originating from an already differentiated intestine. Epithelioid cell cultures of 6-day-old suckling rat intestine were established by sequential trypsinizations of the mucosa. Embryonic intestinal monolayers of quail cells (13 days) were used as control because of their natural cell marker. Six to thirty days after plating, both types of epithelioid cells were associated in heterospecific combination with 5 1/2-day-old chick embryonic small intestinal mesenchyme, after removal of the endoderm by collagenase treatment. In order to test the differentiation capabilities of the associations, they were grafted for 10-12 days into 3-day-old chick embryos. The results show that in such an in vivo culture system, the chimeric associations gave rise to well differentiated intestinal structures indicating that the epithelioid cell cultures derived from late embryonic or neonatal intestine will go through organotypic differentiation when recombined with an appropriate mesenchyme.
Animals↗
Imbalance in brush border enzyme activities as a possible cause of hepatic dysfunction after jejunoileal bypass in the rat.
Previous work in our laboratory and in others suggest that protein malnutrition plays an important role in the pathogenesis of hepatic dysfunction after jejunoileal bypass for morbid obesity. This experimental study was undertaken to attempt to correlate hepatic dysfunction (the criterion used was the bromsulphalein clearance) to morphological and enzymatic adaptation of the functioning intestine in the rat. It was observed that the period of impaired bromsulphalein clearance is concomitant with a slight ileal morphological adaptation and especially with a period of selective adaptation of maltase and sucrase activities, whereas there is no increase in aminopeptidase activity. These data support the hypothesis that after jejunoileal bypass a preferential absorption of carbohydrates along with a protein deficiency state could occur and as in kwashiorkor it results in an impaired nutritional status, a major contributing factor to bypass-induced liver injury.
Aminopeptidases↗