Administration of two antagonists of the cholecystokinin(B)/gastrin receptor does not totally inhibit the pancreatic response to a meal in the pig.

INTRODUCTION AND AIMS: The role of the cholecystokinin B (CCK(B))/gastrin receptor in the pancreatic response to a standard meal was investigated in the pig. METHODOLOGY: Twenty-four pigs were prepared surgically for the collection of the pancreatic juice and an intravenous perfusion. On experimental days, the pigs were perfused with one of two CCK(B)antagonists (L-365,260 or PD 135156) or the vehicle for 2 hours. We offered them a standard meal 30 minutes after the beginning of the perfusion. The pancreatic secretion was collected for 4 hours starting 30 minutes before the perfusion. Its volume was recorded, and the protein concentrations were assayed. RESULTS: Neither antagonist totally abolished the postprandial peak of the pancreatic protein. CONCLUSIONS: We suggest that the stimulation of pancreatic protein secretion by a meal is not mediated by CCK(B)/gastrin receptors. Because we previously showed that the CCK(A)receptor antagonist MK329 was no more able to abolish this response, CCK is probably not responsible for this response.

Apple proanthocyanidins do not reduce the induction of preneoplastic lesions in the colon of rats associated with human microbiota.

Since the gut microbiota metabolizes various dietary constituents unabsorbed by the small intestine and modulates colon function, it plays an essential role in colon carcinogenesis. First, we have developed a model of human microbiota-associated rats (HMA), fed a human-type diet and injected with 1-2,dimethylhydrazine (DMH). We observed that the number and size of DMH-induced aberrant crypt foci (ACF) were significantly higher in HMA rats than in germ-free or conventional rats. Second, we used this model to assess the protective effect of an apple proanthocyanidin-rich extract (APE) on colon carcinogenesis. In this model, ACF number and multiplicity were not reduced by APE at 0.001% and 0.01% in drinking water. They were higher with APE 0.1% than with APE 0.01%. Therefore, the cross-talk between human microbiota and the colon epithelium should be taken into account in carcinogenesis models. Moreover, attention should be paid prior to using proanthocyanidin extracts as dietary supplements for humans.

Brussels sprouts, inulin and fermented milk alter the faecal microbiota of human microbiota-associated rats as shown by PCR-temporal temperature gradient gel electrophoresis using universal, Lactobacillus and Bifidobacterium 16S rRNA gene primers.

We investigated the effect of Brussels sprouts, inulin and a fermented milk on the faecal microbiota diversity of human microbiota-associated (HMA) rats by PCR-temporal temperature gradient gel electrophoresis (PCR-TTGE) using universal and group-specific 16S rRNA gene primers. The HMA rats were submitted to a control diet for 10 d (initial time), then switched to the experimental diets for 4 weeks (final time). Using universal primers, the mean degree of similarity between all faecal samples at initial time was 80.8 %. In the group consuming the control diet throughout the experiment, the mean degree of similarity between the PCR-TTGE profiles at initial v. final time was 76.8 %, reflecting a spontaneous temporal variation. The mean degree of similarity between control and experimental groups at final time was lower, 72.4 %, 74.4 % and 75.6 % for inulin, Brussels sprouts and fermented milk, respectively, indicating a dietary effect on the predominant populations. Using specific primers, bifidobacteria could be detected only in those rats that had consumed inulin, showing a specific increasing effect of this dietary compound. The Lactobacillus population was very heterogeneous at initial time but tended to homogenize within each dietary group. At final time, caecal contents were collected for analysis of SCFA and beta-glucuronidase activity. Inulin and Brussels sprouts increased the butyrate and acetate proportion, respectively, while the fermented milk did not modify the caecal biochemistry. This experiment shows for the first time that cruciferous vegetables are able to alter the diversity and the metabolic activities of the digestive microbiota in HMA rats.