A fluorescent double-labeling method to detect and confirm apoptotic nuclei in Parkinson's disease

Ann Neurol. 1998 Sep;44(3 Suppl 1):S142-8. doi: 10.1002/ana.410440721.


In situ end-labeling (ISEL) has become a widely used method to determine whether cells die via apoptosis by detecting double-stranded DNA breaks that are the result of endonuclease digestion. The enzyme terminal deoxynucleotidyl transferase can be used to label the digested 3'-OH ends of DNA with biotin-, digoxigenin-, or fluorescent probe-conjugated nucleotides. However, both single-stranded and double-stranded DNA breaks can be labeled by this method and therefore ISEL cannot unequivocally demonstrate apoptosis when used alone. We have developed a fluorescent double-labeling method using ISEL combined with the cyanine dye YOYO-1 that binds to DNA. When combined with confocal laser microscopy and deconvolution analysis, YOYO-1 can demonstrate the presence or absence of nuclear chromatin condensation and thus confirm that ISEL-positive nuclei are indeed apoptotic. Preliminary findings indicate that dopaminergic neurons in the substantia nigra compacta die via apoptosis in Parkinson's disease.

Publication types

  • Review

MeSH terms

  • Apoptosis / physiology*
  • Cell Nucleus / genetics*
  • Chromatin / chemistry
  • DNA Fragmentation*
  • Fluorescent Dyes
  • Histocytochemistry
  • Humans
  • Parkinson Disease / pathology*


  • Chromatin
  • Fluorescent Dyes