Figure 10

CBD treatments protect glutamatergic synaptic densities from lesion-related losses. (a) Quantification of song region synaptic densities within unlesioned and lesioned hemispheres of vehicle- and CBD-treated songbirds. In the vehicle group, unilateral microlesions decreased the synaptic density in all three regions examined (HVC, RA, and Area X). Conversely, in the CBD group there was no significant lesion effects in HVC or Area X. This protection was not as robust in RA, although the deficit was decreased. CBD treatment had a profound effect on the post lesion synaptic density compared to post lesion densities of vehicle treated birds in all three regions of interest. (b) Lesion related change in synaptic density expressed as colocalized puncta transformed to percentage of the unlesioned control hemisphere. Within HVC and RA, CBD groups had a significant increase in post-lesion synaptic density while Area X did not differ significantly. This indicates a significant protection of synapses in key areas of vocal production. For analysis, each z-stack image set was post-processed and projected at maximum intensity. Puncta of colocalized VGLUT-2 and PSD-95 within each region were defined for particle analysis with threshold applied from n = 5 animals per group. Glutamatergic synapse densities were then quantified as percent change from the unlesioned control hemisphere. Significance was assessed and appropriate comparisons made using mixed-models ANOVA with Sidak’s correction for multiple comparisons.