Fig. 1

Effect of chronic morphine on D1 receptor expression in glutamatergic projection neurons from the mPFC to the BLA using triple-immunofluorescence method. a Top and bottom panels showed D1R staining (column 1, green color), BDA labeling (column 2, red color), glutamatergic terminal marker VGLUT2 immunoreactivity (column 3 blue color), and coexpression of D1R, BDA, and VGLUT2 (column 4, white color) in slices of the BLA in saline and chronic morphine group. The insets in figures are the magnified views marked with small white rectangles. Scale bar, 5 μm. In higher magnification of areas in the insets, the scale bar is 1 μm. b The averaged optical density of D1R (panel 1), BDA- and VGLUT2-labeled axon terminals (panel 2), and triple labeling clusters in the saline and morphine groups (panel 3) (n = 6, *P < 0.05, compared to saline group). Data are shown as the mean ± SEM