Effect of intestinal microflora on the urinary metabolic profile of rats: a (1)H-nuclear magnetic resonance spectroscopy study.
1. Analysis of urine by (1)H-nuclear magnetic resonance (NMR) spectroscopy is used to detect biochemical disturbances predictive of toxicological changes. Recent studies, using (1)H-NMR spectroscopy have suggested that Alderley Park rats can be classified as hippuric acid (HA) or m-(hydroxyphenyl)propionic acid (m-HPPA) excretors. Evidence exists for the role of intestinal microflora in the excretion of aromatic phenolic compounds including HA and m-HPPA. 2. We sought to investigate whether intestinal microflora contribute to the difference in excretion. Urinary HA and m-HPPA levels were monitored to characterize excretion over time. The effect of intestinal microflora on the (1)H-NMR spectrum was also investigated using antibiotics to sterilize the intestine. Finally, the levels of m-HPPA and phenylpropionic acid (a precursor for HA) were analysed in the caecum and colon (entire tissue, including contents). 3. Characterization confirmed the presence of HA and m-HPPA excretors; enquiries revealed that the rats were obtained from two floors within a barriered breeding unit. Housing the rats from the two floors together for 21 days resulted in comparable levels of HA and m-HPPA excretion demonstrating that the profiles are not stable. 4. Following antibiotic treatment, HA and m-HPPA excretion decreased, indicating that intestinal microflora contribute to the excretion of these compounds. Finally, m-HPPA levels were higher in the colon of rats that excreted m-HPPA whilst PPA was increased in the caecum and colon of rats that excreted HA. 5. These results demonstrate that the observed difference in HA/m-HPPA excretion is due to differences in the intestinal microflora.
Williams
R E
RE
Syngenta Central Toxicology Laboratory, Alderley Park, Macclesfield, SK10 4TJ, UK. becky.williams@syngenta.com
Eyton-Jones
H W
HW
Farnworth
M J
MJ
Gallagher
R
R
Provan
W M
WM
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002432:Cecum / Q000187:drug effects / Q000382:microbiology*; D003106:Colon / Q000187:drug effects / Q000382:microbiology*; D003373:Coumaric Acids / Q000652:urine*; D006626:Hippurates / Q000652:urine*; D008099:Liver / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D051381:Rats; D013997:Time Factors
D000900:Anti-Bacterial Agents; D003373:Coumaric Acids; D006626:Hippurates; C038547:dihydro-3-coumaric acid; C030514:hippuric acid