Fig.6.

Optimized striatal injection coordinates for use in the rat alpha-synuclein pre-formed fibril (aSyn PFF) model. A–B) Comparison of pS129 aSyn expression in the ipsilateral midbrain after two site striatal injections using (A) original, traditionally-used coordinates [34] or (B) optimized coordinates guided by recent findings revealing distinct SNpc-striatal innervation patterns [54]. Neuroanatomical atlas images from Paxinos and Watson [58] depict the general coordinates used for injection. Representative low and high magnification images are shown for ipsilateral midbrain stained with cresyl violet (purple) and antibodies directed against pS129 aSyn (brown). A) Traditional injection coordinates involve injection into the dorsomedial striatum (DMS) and ventrolateral striatum (VLS). Injection into these coordinates induces robust pS129 aSyn expression in the SNpc as well as the ventral tegmental area (VTA). B) Optimized injection coordinates involve injection into the DMS as well as the dorsolateral striatum (DLS). Injection into these coordinates induces robust pS129 aSyn expression that is localized primarily to the SNpc and absent from the VTA. C–D) Quantitation of the percentage of pS129 aggregates in the (C) SNpc or (D) VTA following injection using the original (DMS + VLS) or optimized (DMS + DLS) injection coordinates. Injection using the original coordinates results in ∼80% of aggregates in the SNpc and ∼20% of aggregates in the VTA whereas injection using the optimized coordinates results in ∼90% of aggregates in the SNpc and ∼10% of aggregates in the VTA. Mean values are shown with error bars denoting standard error of the mean. aSyn, alpha-synuclein; PFF, pre-formed fibril; DMS, dorsomedial striatum; VLS, ventrolateral striatum; DLS, dorsolateral striatum; SNpc, substantia nigra pars compacta; VTA, ventral tegemental area; pS129 aSyn, alpha-synuclein phosphorylated at S129.