Fig. 6

Increased fecal SCFA and SBAs may interpret elevated circulating GLP-1 through activating bile acid receptors. A Heatmap showing the top 20 significantly altered fecal metabolites in the HFVK group compared with HF or NC group. The colors changing from blue to red indicate a higher concentration in feces. * represents significant alteration between HFVK and HF group. + represents significant alteration between HFVK and NC group. Significance was determined by Kruskal–Wallis test P < 0.05 or VIP > 1. N = 7 mice/group. B Comparison of fecal histidine and BCAA levels among groups. N = 7 mice/group. C Expression of TGR5 in colon tissue based on IHC staining. Red arrow indicates the distribution of TGR5 in cytoplasm and plasma membrane. Scale bars, 100 μm. D The relative mRNA expression of bile acid receptors in ileocecum (left) and immunohistochemical staining for TGR5 receptor in colon (right). Scale bars, 100 μm. *P < 0.05, ** P < 0.01 by Kruskal–Wallis test with Bonferroni adjustment. N = 4 mice/group. E Fecal MK-7 and MK-4 levels (up) and circulating gla-osteocalcin and GLP-1 levels (bottom). *P < 0.05 by Kruskal–Wallis test with Bonferroni adjustment. N = 5 mice/group