Effect of various modifications in the diet on ileal epithelium renewal in germ-free and conventional rats

Abstract

Summary. Renewal of the ileal epithelium has been studied in germ-free (GF) and conventional (CV) rats fed with a semi-synthetic diet in the following forms : a) pellets sterilized by autoclaving (Pel. Au. diet) ; b) powder sterilized by gamma irradiation ; when given to the rats, its weight in water was added to make a paste (Pa. I. diet) ; c) powder treated as (b) but with 10 p. 100 lactose added (L. Pa. I. diet).Ileal epithelium renewal time was similar in the GF rats fed with the Pel. Au. and Pa. I. diets. It was shorter in the CV rats fed with these two diets than in the GF rats and also in the CV rats given the Pa. I. diet than in those given the Pel. Au. diet.In GF and CV rats fed with the lactose diet, L. Pa. I., ileal epithelium renewal time was similar.These different effects were mainly due to variations in the number of cells produced in Lieberk 3 hn's crypts. They were not related to changes in the intestinal bile salts pool caused by the different diet treatments.Introduction.

In vitro transport of β-lactoglobulin across the jejunum of lactose-fed rats

“…In the present study, the rate of j3-LG absorption through rat jejunum in vitro, as determined by transfer of radioactive material, was slightly higher than that previously reported for rabbit ileum (Marcon-Genty et al, 1989). The nature of the absorbed material provides information on the intracellular processing which occurs during protein transport (Walker at al, 1972;Stern and Walker, 1984 (Armbrecht and Wasserman, 1976;Andrieux et al, 1982;Debiec et al, 1985), steroid absorption (iritani and Wells, 1966) and epithelial cell turnover (Meslin et al, 1981 ). In the present study, we observed reduced tissue conductance and short-circuit current, and decreased (i-LG absorption in vitro by lactose-fed rat jejunum, compared to the control.…”

“…Tissue conductance is known to reflect ion permeation through tight junctions (Madara, 1989), and it has been previously observed that G decreases with cell turnover. Therefore, one could assume that lactose-feeding of adult rats results in reduced leakiness of the intestinal epithelium, and that this is a possible consequence of the previously described slowdown of epithelial cell turn-over (Meslin et al, 1981 Lactase activity of the intestinal mucosa of adult rats is low and lactose is known to be poorly absorbed in the small intestine (Kim et al, 1978). Unhydrolyzed lactose has been shown to enhance phosphate diffusion through direct modification of the intestinal brush-border membrane characteristics of the rat (Debiec and Lorenc, 1985).…”

“…Intestinal epithelium renewal and maturation is affected by many factors such as hormones (Johnson, 1976), microflora (Abrams et al, 1963;Meslin et al, 1974) and food (Ecknauer et al, 1981 Lactose, a disacharide which is known to bypass hydrolysis in adult rat small intestine, may induce changes in intestinal epithelium maturation since 10% lactose feeding has been shown to provoke a significant increase in the epithelium renewal time of the conventional adult rat ileum (Meslin et al, 1981 ).…”

Intestinal mucosal morphometry and ileal epithelial renewal in conventional and germ-free rats fed an amylomaize starch diet

“…As reported in a previous experiment with lactose (Meslin et al, 1981 there was no relation between bile acid pool and epithelial renewal because a similar increase in bile acid pool was observed in CV and GF rats fed amylomaize starch (Sacquet et al, 1983;Andrieux et al, 1989) whereas epithelium renewal was modified only in CV rats.…”

“…In contrast, for CV rats, amylomaize starch considerably increased ileal epithelial renewal time which became similar to that observed for GF rats. This lengthening of ileal epithelial renewal time, as previously observed for lactose in CV rats (Meslin et al, 1981), seems to constitute an indirect effect of amylomaize starch which might be related to fermentation of this starch by bacterial flora.…”