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Rôle des plaques de peyer dans le transfert intestinal de l'uranium chez le rat.


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Grison S, Baudelin C, Ritt J, Dudoignon N, Souidi M, Gueguen Y, Marquette C, Cossonnet C, Voisin P, Paquet P, Gourmelon P, Dublineau I, 4th European Mucosal immunology group meeting, 8-10 octobre 2004, Lyon.

Résumé

In case of contamination by ingestion, digestive tract was the entry way of uranium into organism. We have recently characterized that small intestine was the main area of uranium absorption throughout the gastrointestinal tract. Our investigations aimed at determining if Peyer’s patches played a role in intestinal absorption of uranium in addition to absorption by epithelium. Comparison of uranium passage in mucosa and Peyer’s patches was realized with ex vivo Ussing chambers technical. The apparent permeability was 10-fold higher in the mucosa than in Peyer’s patches (6.21+/-1.21 and 0.55+/-0.35 cm/s*10-6, respectively, n=4). However, presence of uranium in Peyer’s patches was revealed by autoradiography on tissue sections (CR39 plastic) and ICP-Mass Spectrometry of biopsies, prepared by in vivo incubation of an uranyl nitrate solution in ileal segment during two hours. A three months chronic contamination (40mg/L Uranium in drinking water) was then performed in rats, and uranium was quantified in mucosa, Peyer’s patches and mesenteric lymph nodes to define the capacity of lymphoid tissues to accumulate radionuclides. Quantitative analyse of uranium by ICP-MS are in progress. In conclusion, even if the intestinal mucosa is the preponderant way for the transfer of uranium, Peyer’s patches may be a secondary way. Furthermore, the accumulation of uranium in Peyer’s patches could disturb the intestinal immune response due to chemical toxicity (Heavy metal) and/or radiological effects on immune cells.