Feeding manipulation elicits different proliferative responses in the gastrointestinal tract of suckling and weanling rats

Abstract

Food deprivation has been found to stimulate cell proliferation in the gastric mucosa of suckling rats, whereas the weanling period has been reported to be unresponsive in terms of proliferative activity. In the present study we analyze regional differences in the effect of milk or food deprivation on cell proliferation of the epithelia of the esophagus and of five segments of small intestine in suckling, weanling and newly weaned Wistar rats of both sexes. DNA synthesis was determined using tritiated thymidine to obtain labeling indices (LI); crypt depth and villus height were also determined. Milk deprivation decreased LI by 50% in the esophagus (from 15 to 8.35%) and small intestine (from 40 to 20%) of 14-day-old rats. In 18-day-old rats, milk and food deprivation decreased LI in the esophagus (from 13 to 5%) and in the distal segments of the small intestine (from 36-40 to 24-32%). In contrast, the LI of the epithelia of the esophagus (5%) and of all small intestine segments (around 30%) of 22-day-old rats were not modified by food deprivation. Crypt depth did not change after treatment (80 to 120 µm in 14-and 22-day-old rats, respectively). Villus height decreased in some small intestine segments of unfed 14-(from 400 to 300 µm) and 18-day-old rats (from 480 to 360 µm). The results show that, contrary to the stomach response, milk deprivation inhibited cell proliferation in the esophagus and small intestine of suckling rats, demonstrating the regional variability of each segment of the gastrointestinal tract in suckling rats. In newly weaned rats, food deprivation did not alter the proliferation of these epithelia, similarly to the stomach, indicating that weanling is a period marked by the insensitivity of gastrointestinal epithelia to dietary alterations.

Myenteric denervation differentially reduces enteroendocrine serotonin cell population in rats during postnatal development

“…Dietary changes from milk to solid food at weaning are concomitant with alterations in the physiology of intestine (Henning 1981) and also influence the rates of cell proliferation and migration (Klein & McKenzie 1983, Gomes & Alvares 1998, Palanch & Alvares 1998. These ontogenic variations impair the comparisons with adult animals.…”

Cell proliferation and migration in the jejunum of suckling rats submitted to progressive fasting

“…In the jejunum, for instance, there is no difference in proliferative indices between fed and fasting rats (8). However, the villus height was shortened in suckling and weanling rats, and therefore a delay in cell migration was suggested (8).…”

Effects of Fasting at Different Stages of Lighting Regimen on the Proliferation of Jejunal Epithelial Cells During Rat Pup Weaning

“…Although these studies of endogenous factors are informative, there is no information available about the integration of the two major exogenous factors, the light/dark cycle and the presence of food in the small intestine, and their effects on cell proliferation in the small intestine of adult rats, especially during the transition from youth to adulthood. The little information available about the indirect effect of food on cell proliferation during the growth of the small intestine comes from fasting treatment studies, in which it has been demonstrated that, in young rats, fasting reduces cell migration (Koldovský,1966; Gomes and Alvares,1998) as well as the cell proliferation (Palanch and Alvares,1998). These results differ from those observed in adult rats, in which prolonged fasting, that is, two or more days of fasting, resulted in a decrease in cell proliferation and, in some cases, induced morphological damage in the intestinal epithelium (Hooper and Blair,1958; Altman,1972; Aldewachi et al,1975; Goodlad and Wright,1988).…”