**2.2 Results: Immunohistochemical studies in rat brain**

We examined the expression of A1R and P2YR in brain using using immunohistochemistry (Yoshioka *et al*., 2002, Namba *et al*., 2010). Prominent staining of A1R and P2Y2R were observed, particularly in Purkinje cells (Fig. 2A-C). Expression was predominantly restricted to cell bodies and neuronal dendrites. Importantly, co-localization of A1R and P2Y2R was observed in cell bodies within the cerebellum, but was detected within the nucleus of Purkinje cells.

Fig. 2. Confocal images of double immunofluorescence stained A1R (A; green), P2Y2R (B; red), and their merged images (C; yellow) in Purkinje cells. Mol: cerebellar molecular layer, Gr: cerebellar granule cell layer. Co-localization of A1R and P2Y2R (C; yellow) were detected in the soma of the Purkinje cells (arrows). Bar = 50 µm. Fluorescent images were collected via confocal laser scanning microscopy (Zeiss LSM410, Carl Zeiss) and each 10-µm optical slice consisted of a stack of of 20 sections (0.5-µm thick). Serial optical sections were recorded using an air objective lens of (40X, numerical aperture; 0.6).
