Intestinal morphology adjustments caused by dietary restriction improves the nutritional status during the aging process of rats

During the aging process, the body's systems change structurally and loss of function can occur. Ingesting a smaller amount of food has been considered a plausible proposal for increased longevity with the quality of life. However, the effects of dietary restriction (DR) during aging are still poorly understood, especially for organs of the digestive system. This study aimed to describe the body weight, oxidative status and possible morphological changes of the intestinal wall of rats submitted to DR during the aging process (7 to 18 months old). Twelve 7-month-old male Wistar rats fed ad libitum since birth were assigned to two groups: control group (CG, n = 6) fed ad libitum from 7 to 18 months old; and dietary restriction group (DRG, n = 6) fed 50% of the amount of chow consumed by the CG from 7 to 18 months old. The body weight, feed and water intake were monitored throughout the experiment. Blood, periepididymal adipose tissue (PAT) and retroperitoneal adipose tissue (RAT), and the small intestine were collected at 18 months old. The blood was collected to evaluate its components and oxidative status. Sections from the duodenum and ileum were stained with HE, PAS and AB pH 2.5 for morphometric analyses of the intestinal wall components, and to count intraepithelial lymphocytes (IELs), goblet cells and cells in mitosis in the epithelium. DR rats showed a reduction in weight, naso-anal length, PAT, RAT and intestinal length; however, they consumed more water. Blood parameters indicate that the DR rats remained well nourished. In addition, they showed lower lipid peroxidation. Hypertrophy of the duodenal mucosa and atrophy of the ileal mucosa were observed. The number of goblet cells and IELs was reduced, but the mitotic index remained unaltered in both duodenum and ileum. In conclusion, 50% dietary restriction for rats from 7 to 18 months old contributed to improving their nutritional parameters but, to achieve this, adjustments were required in the structure of the body weight and morphology of the small intestine.