Gnotobiotic rodents are increasingly used as model for studying in vivo the characteristics of human colonic flora. However, the value of this model has been poorly assessed. In this study fecal bacterial flora provided either by a conventional rat (group RFR) or by man (group FRH) was administered orally to two groups of 6 germ-free rats. One month later, quantitative bacteriological analyses of feces revealed that bacterial populations were close to those of donors in both groups. The metabolic activity of the genuine flora was further compared in groups RFR and RFH with that of the implanted flora: a) concentrations of each fecal volatile fatty acid and of fecal bile acids were similar in conventional and RFR rats as well as the percentage of transformation of cholesterol into coprostanol (48 p. 100 and 54 ± 5 p. 100 respectively; m ± SD); b) similar concentrations of fecal volatile fatty acids were obtained from the human donor and RFH rats. Alpha, β and ω muricholic acids absent in human donor's feces were found in RFH feces. Cholesterol transformation was lower in RFH rats (48 ± 9 p. 100) than in man (85 p. 100); c) a single dose of lactulose (3 g/kg) increased breath hydrogen excretion in man but not in conventional or in RFR rats and RFH. Chronic lactulose ingestion (3 g/kg d.i.b. for 8 days) had no effect in conventional or RFR rats. Hydrogen excretion was decreased in man, whereas it was significantly increased in RFH rats. In conclusion: a) human fecal flora, when administered orally, is able to colonize germ-free rats, while retaining its specificities; b) metabolic discrepancies between conventional human flora and the same flora implanted in rats could be due to different endogenous substrates (bile acids) as well as to exogenous substrates provided by non-identical diets; c) nutritional data obtained in FH rodents should be carefully interpreted in light of our results.
|Translated title of the contribution||Implantation and metabolic activity of rat and human fecal bacterial flora administered to germ-free rats|
|Number of pages||7|
|Journal||Gastroenterologie Clinique et Biologique|
|State||Published - 1989|