Freund and co-workers utilized a CB1 receptor antibody raised against the C-terminal intracellular tail of CB1 receptor to explore its immunohistochemical distribution within the mouse and rat amygdala (Katona et al., 2001). In general, the densest immunoreactivity was found within the BLA and related cortical-like nuclei, whereas the CeA, MeA, and ICMs were not immunoreactive for CB1. The most prominent feature of the CB1 immunostaining in this study was a dense meshwork of varicose axon collaterals. These axon collaterals were observed to form pericellular arrays around immunonegative cell bodies, while no dendritic staining was observed using this antibody. This pattern of staining was also observed by Elphick and co-workers in rats and mice using a C-terminal antibody (Egertova et al., 2003). In line with ISH data, double-labeled immunofluorescence experiments revealed that 88% of CB1-ir neurons co-expressed CCK with only the large CCK expressing neurons co-expressing CB1 (Katona et al., 2001).
