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Abstract
Cell proliferation and migration in the intestinal crypts, and cell migration in the villus are controlled by different mechanisms in adult rats. In the present study, weanling rats and fasting rats were used to quantitatively study the correlation of cell cycle parameters and epithelial cell migration in crypts and intestinal villi. Eighteen-day-old rats received a single injection of tritiated thymidine [3H]TdR (23:00 h); half of the pups were submitted to fasting 5 h earlier. Cell proliferation was determined in radioautographs of jejunal crypts, on the basis of the labeling indices (LI) taken 1, 8, 13 and 19 h after [3H]TdR. The results showed that the labeling index did not differ 1 h or 19 h after [3H]TdR between the fed (38.7% or 48%) and fasting groups (34.6% or 50.4%). The modified method of grain count halving indicated that cell cycle time did not differ between fed (16.5 h) and fasting rats (17.8 h); the growth fraction, however, had lower values in fasting (59%) than in fed rats (77%). Cell migration in the crypt, estimated by the LI obtained for each cell position, did not change with treatment. As for the villi, the cell migration rate was significantly retarded by 3 cell positions (8%). These results suggest that the cell migration in the villi of weanling pups does not depend directly on the cell proliferation and migration in the intestinal crypt, but is directly affected by the absence of food in the lumen.
Highlights
The epithelium that covers the intestinal mucosa undergoes constant renewal and the cells produced in the crypts migrate into the villi, being lost at their tips
These results suggest that the cell migration in the villi of weanling pups does not depend directly on the cell proliferation and migration in the intestinal crypt, but is directly affected by the absence of food in the lumen
The present results demonstrate that progressive fasting causes a delay in cell migration in the villi of weanling rats
Summary
The epithelium that covers the intestinal mucosa undergoes constant renewal and the cells produced in the crypts migrate into the villi, being lost at their tips. It was demonstrated that cell migration, both within the crypt and the villi, is not dependent on mitotic activity in adult rats [2]. Especially between 18 and 19 days, there is an acceleration of the cell migration rate in the small intestine [5]. During the weaning period the cell migration of the rat is paralleled by increased enzymatic activities mainly of maltase and sucrase in the functional cells covering the villi [6]. The change in diet that progressively occurs during weaning was considered unlikely to play a role in the acceleration of cell migration rate [5]
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Schedule a callMore From: Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas
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