Ileal Compensation for Age-Dependent Loss of Jejunal Function in Rats

Abstract

Adaptive responses of brush border hydrolases and crypt cell proliferation were measured in the jejunum and ileum of 4-mo-old adult and 28-mo-old senescent male Wistar rats. Responses were measured after rats were deprived of food and then refed with a normoprotein diet (17% protein) or an isoenergetic high protein diet (70% protein). The young rats deprived of food then refed for 18 h with the high protein diet showed better body weight recovery than did old animals. Withholding food for 48 h induced a more pronounced drop of sucrase activity in the intestine of the old rats relative to young rats. Refeeding the high protein diet caused a better recovery of sucrase activity in the jejunum of young rats relative to senescent rats. In the aged animals, sucrase activity in the jejunum remained significantly lower after refeeding both diets. Compared with nourished controls, aged rats showed enzyme activity to be completely restored in the ileum. The high protein diet increased aminopeptidase activity in the jejunum and ileum of young rats, in contrast to the senescent rats in which the increase of enzyme activity was restricted to the ileum. In the jejunum of aged rats, the cell migration rate from crypt base to villus tip was reduced after refeeding, but no age-related changes were observed in the ileum. Our results indicate that the jejunum of senescent rats exhibits reduced adaptive capacities that may be partly compensated by enhanced ileal functions.

Severe dietary restriction initiated in aged rats: evidence for poor adaptation in terms of protein metabolism and intestinal functions

“…Maintenance of adequate intestinal structure and function depends on the ability of the intestine to adapt to environmental changes. However, these adaptative capacities are altered during ageing [26]. In our study, intestinal morphometry was affected throughout the experimentation.…”

“…To the best of our knowledge, the response of the small intestine to changes in dietary composition is poorly understood in aged rats and has primarily been investigated in response to short‐term starvation [26–28]. This latter condition leads to rapid and dramatic changes in the morphology of intestinal mucosa [26, 27]. Accompanying the mucosal atrophy, some alterations of intestinal functions were described in this study, in particular concerning the permeability of the mucosa.…”

“…Deleterious effects induced by DR as observed in the present study would reflect a defect of adaptation related to age. Accordingly, previous studies have shown that alterations of intestine structure and function induced by short‐term starvation were more marked in older rats than in younger ones [26, 27].…”

Effects of Guar Gum and Cellulose on Cecal Enzyme Activity and Cecal Short-Chain Fatty Acids in Young and Aged Mice

“…Intestinal microflora extensively degrade gums but only partially degrade cellulose. It is reported that there are some differences in intestinal function between the young adult and aged mice [11] and between the young adult and aged rats [12]. However, there is little information on the cecal enzyme activity and cecal short-chain fatty acids in aged mice fed different dietary fiber.…”

Intestinal adaptation to nutritional stress

“…The adaptive capacities of the hydrolases to the changes in the diet composition during refeeding are strikingly deficient in the proximal intestine of aged rats. However, these proximal deficiencies are compensated by enhanced ileal functions (Reville et al 1991).…”