Fig. 1: Assessment of neuronal viability in the VTA and SNc after AAV1-TH-hαSyn and αSyn PFF injections using TUNEL assay.

A Schematic of the experimental design: Mice received injections of AAV1-TH-hαSyn (1 µL) or αSyn PFF (2 µg/µL; 1µL per hemisphere; 0.5µL in the VTA and 0.5µL in the SNc) into the midbrain. Four weeks post-injection, brain sections were processed for TUNEL staining to assess apoptotic cell death. B Representative fluorescent images of DAPI⁺ nuclei and TUNEL⁺ cells in positive control and experimental sections. Midbrain sections from the contralateral (non-injected) and the ipsilateral (injected) sides of the AAV1-TH-hαSyn and αSyn PFF injection sites display DAPI⁺ nuclei but are entirely TUNEL-negative, indicating no detectable apoptotic cell death. This suggests that neurons in the VTA and SNc remain viable at this time point. Scale bar = 20 µm.