Long term kaolinite ingestion decreased gastric emptying rate as a consequence of duodenal mucosa remodeling
Résumé
Objective Conflicting results showed accelerated or unchanged gastric emptying after long-term supplementation of the diet with kaolinite, a clay used as a protective compound for the injured gut. We aimed to evaluate in conscious pigs, using scintigraphic imaging, the consequences of 4 weeks ingestion of 5% kaolinite on gastric emptying of a semi-solid meal. Since kaolinite ingestion could modify the absorption of nutrients, hence modulating duodeno-gastric reflex, we tested gastric emptying with and without duodenal infusion of lipids. Methods Eight pigs were surgically fitted with a duodenal catheter under general anaesthesia. After one week recovery, the animals were divided in two groups depending of the diet: the first group received 5% kaolinite whereas the second get an iso-caloric diet containing silicate microspheres used as an a-caloric control. After 4 weeks, two scintigraphic sessions were achieved one week apart; one with and one without Intralipid infusion (1ml.min-1 starting 15 minutes before the onset of the meal and continued for 2 hours) in the duodenum. Gastric emptying was measured by automated analysis of scintigraphic images obtained every two minutes during two hours post-prandial. The test meal consisted in 500 ml porridge labelled with 40 MBq 99m-Tc-Colloid. At the end of the experiment, the animals were euthanatized and the small intestine collected for histological analysis. Results Gastric emptying of porridge in the absence of intralipid was unchanged for the two groups (T1+2; 80 ± 13.7 vs 77 ± 10.3 min for kaolinite and microspheres groups, p>0.05). On the contrary, gastric emptying differed between groups in the presence of duodenal intralipid (T1/2; 514 ± 86.8 vs 302 ± 57.3 min for kaolinite and microspheres groups, p<0.01). The reduced gastric emptying rate observed after kaolinite ingestion was associated microscopically at the duodenal level only with significant decreases (p<0.05) in the number of goblet cells (0.03 ± 0.002 vs 0.05 ± 0.002/µm2 for kaolinite and microspheres) and crypts length (418 ± 26.1 vs 594 ± 43.9 µm for kaolinite and microspheres). Conclusion These results suggested that the duodenal structural changes induced by kaolinite resulted in an increased intensity of the afferent limb of the duodeno-gastric reflex.