Figure 2.

Dietary intervention prevents HFD-induced β cell dysfunction and systemic metabolic defects. (a) Schematic representation of the experimental setup. (b) Body weight changes in mice with indicated treatments. Data represents mean ± SEM (n = 7–9 mice per group). (c) Overnight fasting blood glucose levels (left) and plasma insulin levels (right) of Chow, HFD, and HFD-Chow mice. Data represent mean ± SEM (n = 4–5 mice per group); ***, P < 0.001; one-way ANOVA. (d) GTT (left) and ITT (right) of Chow, HFD, and HFD-Chow mice. Data represent mean ± SEM (n = 5 mice per group), ***, P < 0.001, HFD vs. Chow; ^##, P < 0.01, ^###, P < 0.001, HFD-Chow vs. HFD; two-way ANOVA with multiple comparisons. (e) Representative H&E staining of pancreas sections from Chow, HFD, and HFD-Chow mice (left panel), and islet number per pancreas section (right). Scale bar, 1 mm. Data represent mean ± SEM (n = 24 pancreas sections from six mice/group; at least 4 sections/mouse).***, P < 0.001; one-way ANOVA. (f) Representative IHC images of mouse pancreas sections from Chow, HFD, and HFD-Chow mice immune-stained for insulin (brown) and counterstained with hematoxylin (blue; left). Quantitation of β cell mass in the pancreas of Chow, HFD, and HFD-Chow mice (right). Scale bar, 500 μm. Data represent mean ± SEM (n = 5–7 mice per group). **, P < 0.01; ***, P < 0.001; one-way ANOVA. (g) Perifusion analyses of dynamic glucose-stimulated insulin secretion in islets from Chow, HFD, and HFD-Chow mice (left) and biphasic insulin release levels (right). Each islet sample was pooled from at least three animals. Data represent mean ± SD (n = 3 technical replicates). ***, P < 0.001; one-way ANOVA. (h) ATP/ADP ratios of islets from Chow, HFD, and HFD-Chow mice under low-glucose (2.8 mM) or high-glucose (16.8 mM) treatments, islet samples were pooled from at least three animals. Data represent mean ± SEM (n = 6–7 replicates of islet samples, each sample represent 20 IEQ islets); ***, P < 0.001; one-way ANOVA. (i) Glucose (16.8 mM) stimulated Ca²⁺ influx in single islet β cells in mice from Chow (n = 128 cells), HFD (n = 178 cells), and HFD-Chow (n = 214 cells) groups. Each islet sample was pooled from at least three animals. Data represent mean ± SEM; two-way ANOVA. (j) Differential gene expression analysis of RNA-Seq of mouse islets from Chow, HFD, and HFD-Chow groups (RNA isolation from islets pooled from three mice). Log₁₀ transferred fold change expression levels of all highly expressed genes (fragments per kilobase of exon model per million mapped fragments >1) in indicated comparisons are shown in the scatter plot. Reversible Genes with |log₂FC| > 0.5, P < 0.05 were additionally marked in red (upregulated) and blue (downregulated). (k) GO analysis of Reversible Genes in i. Most significant and nonredundant biological processes with respective gene numbers and P values are shown. All panels report data verified in at least two independent experiments.