Fig. 6. Transplantation of the fecal microbiota of GP2-treated mice increases GLP-1 secretion.

a Schematic diagram of the pharmacodynamic experiment. In brief, 6-week-old male mice were fed a high-fat diet for 20 weeks, and then the gut microbiota was depleted by antibiotics in drinking water for 3 days. Twelve hours after last dose of antibiotics given, the mice were oral administered the feces (resuspended in PBS) isolated from vehicle (Re-Veh) or GP2-treated mice (Re-GP2) for three times (on day 0, day 3, day 6). Then the mice were fed a high-fat diet for another 3 weeks. b The mice were fasted for 6 h and an oral glucose tolerance test (OGTT) was conducted after glucose (2.0 g/kg) after administration by gavage (n = 8–10). c Area under the curve of glucose level in 90 min of OGTT in b (n = 8–10). d The levels of the individual taurine-conjugated bile acids TαMCA, TβMCA, and TUDCA were measured in the feces (n = 5–6). e Plasma concentration of active GLP-1 in Re-Veh and Re-GP2 mice in response to oral administration of 2.0 g/kg glucose (n = 5–6). f Area under the curve of active GLP-1 level in 15 min after glucose challenge in e. g, h Immunoblot (g) of pro-glucagon in RIPA lysis extracts from the ilea of Re-Veh and Re-GP2 mice and the quantification (h) (n = 5). The results are shown as the mean ± s.e.m., *P < 0.05, **P < 0.01, ***P < 0.001 compared with Re-Veh.