CONVENTIONALIZATION OF GERM-FREE RATS REVERSES THE DISABILITY OF RHEIN ANTHRONE TO INDUCE LAXATION

This study shows that rhein anthrone has no laxative potency in germ-f ree rats because after intracaecal administration of a dose of 50 mg/k g the large intestine transit exceeded 240 min. The time course of the laxative potency of rhein anthrone injected intracaecally was evaluat ed after peroral inoculation of germ-free rats with the caecal content s of conventional rats. Large intestine transit was measured at consec utive periods, on days 0, 1, 2, 3 and 5 after peroral inoculation. It appeared that 1 day after peroral inoculation the laxative potency of rhein anthrone was already established (large intestinal transit < 10 min) and laxation remained on the following days (days 2, 3 and 5). We conclude that rhein anthrone is inactive in germ-free rats and acquir es laxative potency after peroral inoculation of germ-free rats with c aecal contents of conventional rats.