Pig bile powder maintains blood glucose homeostasis by promoting glucagon-like peptide-1 secretion via inhibiting farnesoid X receptor

Figure 4 Bile powder regulated blood glucose homeostasis via inhibiting intestinal farnesoid X receptor signaling pathway. A: Schematic diagram. Mice were fed a high-fat diet (HFD) for 6 weeks and were injected with streptozotocin (STZ) (50 mg/kg, intravenous) to induce blood glucose disorder. Mice were fed a HFD for an additional 6 weeks. The mice were randomly divided into three groups (n = 5 per group): The HFD + STZ group; The bile powder (BP) group (75 mg/kg/day BP, intragastric gavage); The BP + fexaramine group (75 mg/kg/day BP, intragastric gavage + 100 mg/kg/day fexaramine, intragastric gavage); B: Intestinal immunohistochemistry analysis of the farnesoid X receptor (scale bars = 100 μm); C: Relative expression of fibroblast growth factor 15 transcription in the ileum; D: Serum fibroblast growth factor 15 levels; E: Oral glucose tolerance test after the 30-day treatment; F: The area under the curve of the oral glucose tolerance test after the 30-day treatment. Data are shown as mean ± SEM. P < 0.05 compared between groups. Statistical analysis was performed using Student’s t-test. ^aP < 0.05. ¹High-fat diet + streptozotocin vs bile powder. ²Bile powder vs bile powder + fexaramine. FXR: Farnesoid X receptor; FEX: Fexaramine; HFD: High-fat diet; STZ: Streptozotocin; BP: Bile powder; OGTT: Oral glucose tolerance test; RT-PCR: Real-time polymerase chain reaction; IHC: Immunohistochemistry; AUC: Area under the curve.