Regulatory effects of Dangua Fang on the NAMPT/NAD+/SIRT1 axis and amino acid metabolism in type 2 diabetic rats

Figure 1 Experimental procedure. STZ: Streptozotocin; T2DM: Type 2 diabetes mellitus; CON: Control group; MOD: Model group; DFG: Dangua Fang group; MET: Metformin group; SW: Sterile water; DGF: Dangua Fang; NAMPT: Nicotinamide phosphoribosyltransferase; NAD⁺: Nicotinamide adenine dinucleotide; SIRT1: Sirtuin 1.

Figure 2 Comparison of body weight changes. ^aP < 0.05 vs the control group; ^bP < 0.01 vs the control group; ^cP < 0.05 vs the model group; ^dP < 0.01 vs the model group. n = 8 per group. Data are expressed as mean ± SD. CON: Control group; MOD: Model group; DFG: Dangua Fang group; MET: Metformin group.

Figure 3 Comparison of hepatic histopathological changes. A: Hematoxylin and eosin staining of liver tissue (× 100/200); B: Masson staining of liver tissue (× 100/200); C: Oil red O staining of liver tissue (× 100). HE: Hematoxylin and eosin; CON: Control group; MOD: Model group; DFG: Dangua Fang group; MET: Metformin group.

Figure 4 Western blot protein bands and hepatic immunohistochemical staining. A: Protein bands of nicotinamide phosphoribosyltransferase and sirtuin 1; B and C: Hepatic immunohistochemical staining of Nicotinamide phosphoribosyltransferase and sirtuin 1 (× 200). CON: Control group; MOD: Model group; DFG: Dangua Fang group; MET: Metformin group; NAMPT: Nicotinamide phosphoribosyltransferase; SIRT1: Sirtuin 1.

Figure 5 Comparison of amino acid metabolic changes. A: Principal component analysis score scatter plot of all samples; B-D: Principal component analysis score scatter plots and permutation test results of orthogonal projections to latent structures-discriminant analysis models for each comparison group; E: K-means clustering of differential metabolites; F: Hierarchical clustering heatmaps of differential metabolites; G: Classification of differential metabolites. PC1: Principal component 1; PC2: Principal component 2; CON: Control group; MOD: Model group; DFG: Dangua Fang group; MET: Metformin group.

Figure 6 Differential metabolic pathways and receiver operating characteristic analysis. A-C: Pathway analysis plots for each comparison group; D-F: Receiver operating characteristic curves of differential metabolites for each comparison group. CON: Control group; MOD: Model group; DFG: Dangua Fang group; MET: Metformin group; AUC: Area under the curve.

Figure 7 Correlation analysis of nicotinamide phosphoribosyltransferase/nicotinamide adenine dinucleotide/sirtuin 1 axis and metabolites. NAMPT: Nicotinamide phosphoribosyltransferase; NAD⁺: Nicotinamide adenine dinucleotide; SIRT1: Sirtuin 1.