The aim of this study was to compare the effects of the mixture of Lactobacillus delbrueckii subsp. rhamnosus strain GG, Bifidobacterium lactis Bb12, and inulin on intestinal populations of lactobacilli, bifidobacteria, and enterobacteria in adult and elderly rats fed the same (in quality and quantity) diet. The portal plasma levels of two neuropeptides, neuropeptide Y (NPY) and peptide YY (PYY), were also evaluated to assess the physiological consequences of the synbiotic treatment for the gastrointestinal (GI) tracts of rats of different ages. Adult (n ‫؍‬ 24) and elderly (n ‫؍‬ 24) male rats were fed the AIN-93 M maintenance diet. After 2 weeks of adaptation, the diet of 12 rats of each age group was supplemented with 8% inulin and with strains GG and Bb12 to provide 2.2 ؋ 10 9 CFU of each strain g ؊1 of the diet. Blood and different regions of the GI tract were sampled from all rats after 21 days of the treatment. Treatment with the mixture of strain GG, strain BB12, and inulin induced significantly different changes in the numbers of lactobacilli, bifidobacteria, and enterobacteria of the stomach, small intestine, cecum, and colon microflora. Moreover, the GG, BB12, and inulin mixture increased the concentrations of NPY and PYY for adult rats. For the elderly animals, the PYY concentration was not changed, while the NPY concentration was decreased by treatment with the GG, BB12, and inulin mixture. The results of the present study indicate that the physiological status of the GI tract, and not just diet, has a major role in the regulation of important groups of the GI bacteria community, since even the outcome of the dietary modification with synbiotics depends on the ages of the animals.The composition of the gastrointestinal (GI) microflora changes with increasing age of the host (34). These changes involve a decrease in the number and diversity of bifidobacteria and bacteroides and an increase in the number of enterobacteria, clostridia, streptococci, and enterococci in elderly humans (17,20,51) and in older animals (5).The age-related changes in the GI bacterial community in elderly humans are likely related to changes in nutritional habits, since it is well recognized that diet/dietary components codetermine the spectrum of intestinal microflora (2,18,28,33,37). In particular, aging is associated with the decrease in daily fiber intake (27) related to the prolongation of mastication (42), the decline in olfactorial and gustatorial sensitivity (24), and a decrease in cognition (36). However, aging is also associated with alterations of GI physiology and function, such as gastric hypochlorhydria, alterations in intestinal motility, and decreased colonic transit time (23,31,44). Changes in GI tract physiology during the aging process may allow specific bacterial populations to take advantage of novel ecological niches, thereby altering the composition of the GI microbiota, in turn affecting intestinal homeostasis and function (22,28).Pro-and prebiotics and their combination (synbiotics) have been shown to...

Interdigestive intestinal motility, and especially phase III of the migrating myoelectric/motor complex (MMC), is responsible for intestinal clearance and plays an important role in prevention of bacterial overgrowth and translocation in the gut. Yet previous results from gnotobiotic rats have shown that intestinal microflora can themselves affect the characteristics of the myoelectric activity of the gut during the interdigestive state. Given that the composition of the intestinal microflora can be altered by dietary manipulations, we investigated the effect of supplementation of the diet with synbiotics on intestinal microflora structure and the duodenojejunal myoelectric activity in the rat. To reduce animal distress caused by restraint and handling, which can itself affect GI motility, we applied radiotelemetry for duodenojejunal EMG recordings in conscious, freely moving rats. Thirty 16-month-old Spraque-Dawley rats were used. The diet for 15 rats (E group) was supplemented with chicory inulin, Lactobacillus rhamnosus and Bifidobacterium lactis. The remaining 15 rats were fed control diet without supplements (C group). Three rats from each group were implanted with three bipolar electrodes positioned at 2, 14 and 28 cm distal to the pylorus. After recovery, two 6 h recordings of duodenojejunal EMG were carried out on each operated rat. Subsequently, group C rats received feed supplements and group E rats received only control diet for 1 week, and an additional two 6 h recordings were carried out on each of these rats. Non-operated C and E rats were killed and samples of GI tract were collected for microbiological analyses. Supplementation of the diet with the pro-and prebiotics mixture increased the number of bifidobacteria, whereas it decreased the number of enterobacteria in jejunum, ileum, caecum and colon. In both caecum and colon, the dietary supplementation increased the number of total anaerobes and lactobacilli. Treatment with synbiotics increased occurrence of phase III of the MMC at all three levels of the small intestine. The propagation velocity of phase III in the whole recording segment was also increased from 3.7 ± 0.2 to 4.4 ± 0.2 cm min −1 by dietary treatment. Treatment with synbiotics increased the frequency of response potentials of the propagated phase III of the MMC at both levels of the jejunum, but not in the duodenum. In both parts of the jejunum, the supplementation of the diet significantly decreased the duration of phase II of the MMC, while it did not change the duration of phase I and phase III. Using the telemetry technique it was demonstrated that changes in the gastrointestinal microflora exhibited an intestinal motility response and, more importantly, that such changes can be initiated by the addition of synbiotics to the diet.

No abstract

Daily secretion of pancreatic juice, including postprandial responses to food, was investigated in two groups of calves: preruminant (fed with liquid food) and ruminant (fed with solid food). Male Friesian calves (1 week old and 6 weeks old) were surgically fitted with a pancreatic duct catheter, duodenal cannula and two duodenal electrodes. Continuous 24 h collections of pancreatic juice and myoelectrical recordings were performed with minimal restraint and disturbance of animals. In both groups of calves clear periodic fluctuations in pancreatic juice secretion (volume, protein output and trypsin activity) coinciding with duodenal migrating myoelectric complexes (MMC) were recorded. Secretion of juice per cycle and per day was greater in ruminant calves, but the frequency and amplitude of cycles were lower in this group. There were no differences between day and night-time preprandial pancreatic cycles and duodenal MMC in preruminant calves, whilst in ruminant calves, evening MMC were longer than morning MMC. The pancreatic cephalic phase (increase of volume flow, protein output and trypsin activity during and just after food intake) was significant only in preruminant calves following morning feeding. Postprandial pancreatic cycles did not differ from preprandial cycles, except the pancreatic cycle (juice volume and trypsin activity) in which food was offered in preruminant calves. No gastric or intestinal phase was observed in either group of calves. In conclusion, biological cycles of the gastrointestinal tract are present in both preruminant and ruminant calves, and these cycles evolve along with the change from liquid to solid food.

This study investigated the effect of the change of diet and feeding regimen at weaning on myoelectrical activity of the intestine of piglets. For this purpose the electromyographic recordings of duodenal myoelectrical activity were carried out in relation to the different weaning status of piglets. Six piglets, in two experimental trials were surgically modified with two serosal, bipolar electrodes on the duodenum. The myoelectrical activity was recorded in the same piglets before weaning when they were sucking their sow and after weaning when the diet was changed to solid dry food (standard commercial concentrate for weaned pigs). In sucking piglets the intestinal myoelectrical activity pattern exhibited triple-phased migrating myoelectric complex (MMC), undisturbed by sow nursing. After weaning, feeding with solid food induced a long-term post-prandial pattern with higher frequency of electrical response activity (ERA) when compared with phase II of the MMC. The duration of the MMC cycles increased with time over the experiment by proportionately 0•11 and 0•14 in the periods before and after weaning. However, weaning significantly shortened MMC cycle duration by proportionately 0•21. The duration of phase II was significantly prolonged with time over the experiment by 0•07 to 0•10 and it was not affected by weaning. Phase III of MMC were of constant duration over the whole experimental period.In summary, changes in the diet and feeding regimen have an influence on the characteristics of intestinal myoelectrical activity in piglets around weaning.