Fig. 2.

sq-IHC analysis of CB₁ receptor at neuronal subtypes and synapses in the striatum of 12-week-old R6/2 mice. (A and B) Representative dual-labeled images of CB₁ receptor (Lin et al., 2001) and neuropeptide Y (NPY; Blazquez et al., 2011) interneurons in the striatum and the regions of interest (ROIs; see Materials and methods) created to identify positive CB₁ receptor pixels (CB₁ ROI), NPY pixels (NPY ROI), and overlapping CB₁ receptor and NPY pixels [(CB₁ ‘AND’ NPY ROI); scale bar: 20 mm]. (C) CB₁ receptor expression at indirect pathway [leucine-enkephalin (LEnk)] and direct pathway [substance P (SubP)] axonal collaterals, parvalbumin (Parv) and NPY interneurons in the striatum of wild-type and R6/2 mice (n = 4–5 mice, *P < 0.05, ***P < 0.001). (D) CB₁ receptor expression at NPY/neuronal nitric oxide synthase (nNOS—) interneurons in the striatum of wild-type and R6/2 mice (n = 5 mice). All values are expressed as mean ± SEM normalized to age-matched wild-type CB₁ receptor expression, and analysed by two-tailed Student’s t-test to their wild-type littermates.