Wspólnotowy Serwis Informacyjny Badan i Rozwoju - CORDIS

Changes in duodenal vagal afferents sensitivity induced by acute alimentary switch in piglets

Changes in diet composition such as the one that occurs at weaning alter gastric emptying and gastro-intestinal motility. The underlying factors for theses changes may include adaptation of duodenal vagal receptors. The aim of this study was to evaluate the characteristics of multimodal duodenal receptors before and immediately after artificial weaning in 20 anaesthetized 40 kg pigs. Twenty duodenal vagal afferents were recorded from the cervical vagus using the single fibres method. 10 pigs were fed with a milk-based diet (MD) for one month while the diet of the 10 other pigs was changed for plant-based diet (PD) the day preceding the recording session.

The behaviour of the receptors was tested before and after challenges with duodenal intralipid and close intra-arterial injection of CCK, 5-HT or Capsaicin with and without isobaric duodenal distensions at 20, 40 and 60 mmHg. All receptors were slowly adapting C type fiber with a receptor field located 6-7 cm distal to the pylorus. Comparisons between groups were achieved by normalizing the firing pattern to that recorded during 20, 40 and 60 mmHg distensions in the unchallenged condition.

Intralipid induced an overall reduction in basal discharge irrespective of the diet. In contrast, the rate of discharge during distension (20, 40 and 60 mmHg) combined with duodenal intralipid was significantly larger for MD compared with PD (104 +/- 18.2 vs 49 +/- 15.8 spikes.5s-1 for 20mmHg distension, p<0.05). Similarly, the rate of discharge observed during distensions performed with CCK (90 +/- 14.1 vs 51 +/- 16.3 spikes.5s-1 for 20mmHg distension, p<0.05) and with 5-HT (168 +/- 23.2 vs 43 +/- 14.9 spikes.5s-1 for 20mmHg distension, p<0.05) were greater for MD compared with PD while CCK and 5-HT without distension were equally stimulating for MD and PD.

No significant difference was found between groups during Capsaicin infusion irrespective of the stimulating pressure. In conclusion, a plant-based diet, when compared to a milk-based diet, results in an overall decrease in mechanical sensitivity of duodenal neurones during chemical challenge, but not in basal conditions.

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