Amelioration of gut dysbiosis and gastrointestinal motility by konjac oligo-glucomannan on loperamide-induced constipation in mice

Konjac oligo-glucomannan (KOG) is a non-digestible dietary fiber that is resistant to digestion and absorption in gastrointestinal (GI) tract. Thus, it might be used as an alternative management for constipation. The aim of this study was to evaluate the effects of KOG on gut motility and microbiota to relieve constipation in mice. Mice received Bifidobacterium animalis, lactulose, konjac glucomannan (KGM), or KOG for 14 d. Constipation was induced by 5 mg/kg loperamide days 12 through 14 in all groups except the control. Defecation frequency, small intestinal transit, and total gut transit time were indicated by counting the number of feces, and using charcoal meal and Evans blue as markers, respectively. Smooth muscle (SM) contraction and gut motility were evaluated by organ bath and GI motility monitor system. Gut microbiota were measured by fluorescence in situ hybridization technique. KOG significantly (P < 0.01) increased defecation frequency and small intestinal transit but decreased total gut transit time when compared with the constipation-without-treatment group. These results were similar to the effects of Bifidobacterium animalis, lactulose, and KGM. KOG ameliorated the effect of loperamide on contraction frequency of distal colonic circular SM. The motility patterns were changed in the KOG group from non-propagation to propagation contraction. KOG significantly inhibited the effects of loperamide on gut microbiota by increasing the numbers of Bifidobacterium spp. and decreasing the numbers of Clostridium spp. and Bacteroides spp. These results suggest that KOG acts as a prebiotic and stimulant laxative for relief and prevention of constipation.