NPY, Parv and ChAT immunoreactivity in the striatum of rats 5 weeks post-injection of Empty vector (a–c), Hdh8 (d–f), HD20 (g–i), HD70 (j–l). (m) Stereological quantification of striatal interneuron cell death. Each bar represents mean±SEM (n=6) of the number of cells counted in the ipsilateral injected hemisphere as a percentage of the cells counted in the contralateral hemisphere. AAV-HD70 expression led to the loss of 47.7±7.0% of NPY-positive interneurons and 48.7±6.4% of parv-positive interneurons in the ipsilateral striatum. Expression of AAV-HD70, -HD20, or -Hdh8 also led to loss of ChAT-positive interneurons (HD70, 58.8±11.4% cell loss; HD20, 41.6±6.9% cell loss; Hdh8 45.5±12.7% cell loss; one-way ANOVA with post-hoc analysis and Bonferroni correction, **p<0.01, ***p<0.001). Scale bars, 50 µm.