Role of Diet in the Determination of Jejunal Sucrase Activity in the Weanling Rat

Abstract

SummaryThis study was designed to determine the critical difference between rat milk and rat chow with respect to their effects on jejunal sucrase activity during the fourth postnatal wk. Rats were weaned onto special diets on postnatal day 17, and jejunal sucrase was assayed on day 28. A pelleted diet containing lactose as sole carbohydrate did not cause depression of sucrase activity. Sucrase values (pmoles/hr/mg protein) were 10.49 k 0.81 (n = 15) for the lactose chow and 6.65 + 0.29 (n = 16) for the sucrose chow. This indicates that the nature of the dietary carbohydrate does not account for the sucrase differences of weaned and nonweaned animals. Likewise, the physical consistency of the diet is unimportant because sucrase values were just as high on a liquid diet (10.91 f 0.77 pmoles/hr/mg protein; n = 8) as on the solid diets. However, when the relative proportions of carbohydrate and fat in the diet were varied, there were significant effects on sucrase activity; values on a low carbohydrate diet (4.30 k 0.33 pmoles/ hr/mg protein; n = 8) being less than one-half those on a high carbohydrate diet (10.91 + 0.77 pmoles/hr/mg protein; n = 8). SpeculationThe terminal maturation of jejunal sucrase is dependent on the normal process of weaning. The critical feature of the weanling diet is that it is a high-carbohydrate, low-fat diet. In the absence of this dietary transition, intestinal development remains incomplete.The postnatal development of the rat small intestine is characterized by an array of enzymic changes during the third wk of life. Some enzymes (such as lactase and the lysosomal hydrolases) which have high activities at birth, decline at this time; others (such as maltase and sucrase) show dramatic increases in their activities. The details of these enzymic changes and their irnportance in the dietary transition from milk to solid food have been frequently reviewed (6,15,16,19,27). There is good evidence to indicate that the enzymic changes are cued by the glucocorticoid (4,8,14,15,16,18,22) and the thyroid (13,20,21,34) hormones. Although there is a temporal correlation between the maturation of the intestinal mucosa and the spontaneous process of weaning, the possibility that the ontogenic changes in the intestine are diet initiated has generally been discredited (4,10,17,23). For instance, rat pups which are prevented from weaning show an initial rise of jejunal sucrase at 17 days of age, just as in control pups (17). However, the same study showed that by the fourth postnatal wk, diet is an important determinant of sucrase activity. In control (weaned) pups, sucrase activity had plateaued at adult levels by day 27, whereas nonweaned pups had enzyme activities less than one-half those of controls and equivalent to activities usually seen on approximately day 20 (17). Thus, it seems that the normal process of weaning is necessary for the terminal maturation of jejunal sucrase activity. The aim of the current study was to determine the critical feature of the dietary change from milk to chow whic...

Early Weanling and Precocious Development of Small Intestine in Rats: Genetic, Dietary or Hormonal Control

“…The fact that the small intestine of prolonged nursed rats shows similar development of maltase and sucrase activities at day 25 without eating a sucrose-and glucose-polymer-containing laboratory chow also suggests a basically preprogrammed control that cannot be overridden by diets at least of these two disaccharidases in their postnatal development. A similar increase in sucrase is also obsewed by Henning and Guerin (20) in nonweaned rats at day 28.…”

Developmental Changes in Intraepithelial T Lymphocytes and NK Cells in the Small Intestine of Neonatal Rats

“…During the suckling period, luminal factors begin to stimulate immune cells present in the gut compartment, and this challenge is increased by solid diet ingestion that in rats begins spontaneously during the late suckling period (23). In humans, although intestinal IEL are present during gestation, stimulation by luminal factors clearly determines their number, which increases postnatally up to 10-fold by 1-2 year of age (24).…”

Riboflavin deficiency: early effects on post-weaning development of the duodenum in rats

“…Animal studies have identified qualitative and quantitative changes to the gastrointestinal tract following alterations in diet at this time. For example, weaning rats fed a diet low in carbohydrate but high in fat have a reduced expression of the brush-border enzyme sucrase, whereas the expression increases in those animals fed a diet high in carbohydrates but low in fat (Henning & Guerin, 1981). In lambs the transition from milk to grass results in a reduction in the concentration of monosaccharides in the lumen.…”