Received August 11, 2005
Revised September 19, 2005
Accepted after revision October 31, 2005
GI and epithelial physiology
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Relationship between dietary induced changes in intestinal commensal microflora and duodeno-jejunal myoelectric activity monitored by radiotelemetry in the rat in vivo
Violetta Lesniewska 1*,
Ian Rowland 1,
Helle N. Laerke 2,
George Grant 3,
Patrick J. Naughton 1
1 University of Ulster
2 Danish Institute of Agricultural Sciences
3 Rowett Research Institute
* To whom correspondence should be addressed. E-mail: v.lesniewska{at}ulster.ac.uk.
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Abstract |
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Interdigestive intestinal motility and especially phase III of 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 form Gnotobiotic rats showed that intestinal microflora can itself affect the characteristics of the myoelectric activity of the gut during the interdigestive state. Given that in the conventional state 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 duodeno-jejunal myoelectric activity in the conventional rat model. To reduce animal distress, caused by restraint and handling that can itself affect GI motility, we applied radiotelemetry for duodeno-jejunal EMG recordings in conscious, freely moving rats.
Thirty, 16-months-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 duodeno-jejunal EMG were carried out on each operated rat. Subsequently, group C rats received feed supplements and group E rats received only control diet for one week, and an additional two, 6-hours 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 diet supplementation increased the number of total anaerobes and lactobacilli. Synbiotics treatment increased occurrence of Phase III of MMC in all three levels of 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. Synbiotics treatment increased the frequency of response potentials of the propagated phases III at both levels of jejunum, but not at duodenum. In both parts of jejunum, the supplementation of the diet significantly decreased the duration of Phase II of MMC, while it did not change the duration of the Phase I and Phase III of the MMC.
We conclude that the radiotelemetry method can be successful for the evaluation of the intestinal motility in rats. Furthermore, 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 the synbiotics to the diet.
Key Words:
EMG, Jejunum, Smooth muscle
