Molecular imaging of cell death in an experimental model of Parkinson's disease with a novel apoptosis-targeting peptide

Purpose: We used a novel apoptosis-targeting peptide called ApoPep-1 in order to evaluate whether ApoPep-1 can be used as a diagnostic indicator in a model of Parkinson's disease (PD). Procedures: 1-Methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP) was given to mice to produce the PD model. Cy7.5-labeled ApoPep-1 was given intravenously and optical imaging was taken at 1, 2, and 3 weeks after MPTP treatment. Immunohistochemical study was performed with brain sections. Results: Increased ApoPep-1 signal was observed in the brain of MPTP-treated mice by in vivo and ex vivo imaging study. With histological evaluation, ApoPep-1 signal demonstrated a strong correlation with loss of dopaminergic neurons or increase of apoptotic cells. Moreover, the neuroprotective effect of amantadine in the MPTP model was effectively evaluated using optical imaging of ApoPep-1. Conclusions: We conclude that ApoPep-1 is the effective probe for imaging of apoptosis in the MPTP model and can be applied in brain diseases with apoptosis.