Facilitating effects of berberine on rat pancreatic islets through modulating hepatic nuclear factor 4 alpha expression and glucokinase activity

Figure 4 Double immunofluorescence staining for HNF4α (red) and insulin (green) of rat pancreatic islets. After treatment with indicated concentrations of berberine or GB for 24 h, islets were fixed and stained with anti-HNF4α and anti-insulin antibodies. Images of islets were taken at the corresponding depth by confocal laser microscopy (× 40). A: Control, B: 1 μmol/L GB; C to F: Represent 1, 3, 10 and 30 μmol/L berberine. Bar in the figure indicates 20 μm. Apparent nuclear localization of HNF4α could be observed in all groups of islets, while insulin fluorescence was diffusely distributed in cytoplasma of β cells. In the islets treated with various concentrations of berberine, the red fluorescence emitted was comparatively intense, suggesting up-regulated expression of HNF4α, while no obvious difference of HNF4α staining was found between control and GB treated islets.