Figure 3.

The compensatory beta cell mass expansion induced by high-fat diet in mice was not observed after butyrate administration. Photomicrographs of pancreatic islets processed for insulin immunoperoxidase (a–d) (brown) or for double immunofluorescence to detect insulin (red) and glucagon (yellow)(f–i). Note the increase in number and size of insulin-labelled islets (b,g), with no change in the islet cytoarchitecture (g), in high-fat diet-fed mice (HF) in comparison with control group (C) (a,f). This increase in the relative volume of insulin-producing beta cells induced by HF diet was not observed after butyrate treatment (HFB) (d,i) as compared to its control (CB) (c,h); this result was confirmed quantitatively as shown in (e). Bars in graph (e) represent means + SE of six mice per group. Images were obtained by light (a–d) or confocal laser microscopy (f–i). Scale bars, 500 µm in (a–d); 50 µm in (f–i). ***P < 0.0001 compared to C group; ^###P < 0.0001 compared to HF group. (A color version of this figure is available in the online journal.)