Critical role of mitochondrial reactive oxygen species formation in visible laser irradiation-induced apoptosis in rat brain astrocytes (RBA-1)

Mei Jie Jou, Shuo Bin Jou, Hung Ming Chen, Chi Hung Lin, Tsung I. Peng*

*Corresponding author for this work

Research output: Contribution to journalArticle

72 Scopus citations

Abstract

Laser irradiation-induced phototoxicity has been intensively applied in clinical photodynamic therapy for the treatment of a variety of tumors. However, the precise laser damage sites as well as the underlying mechanisms at the subcellular level are unknown. Using a mitochondrial fluorescent marker, Mito Tracker Green, severe mitochondrial swelling was noted in laser-irradiated rat brain astrocytes. Nucleus condensation and fragmentation revealed by propidium iodide nucleic acid staining indicated that laser-irradiated cells died from apoptosis. Using an intracellular reactive oxygen species (ROS) fluorescent dye, 2′,7′-dichlorofluorescin diacetate, heterogeneous distribution of ROS inside astrocytes was observed after laser irradiation. The level of ROS in the mitochondrial compartment was found to be higher than in other parts of the cell. With another ROS fluorescent dye, dihydrorhodamine-123, and time-lapse laser scanning confocal microscopy, a substantial increase in mitochondrial ROS (mROS) was visualized in visible laser-irradiated astrocytes. The antioxidants melatonin and vitamin E largely attenuated laser irradiation-induced mROS formation and prevented apoptosis. Cyclosporin A (CsA), a mitochondrial permeability transition (MPT) blocker, did not prevent visible laser irradiation-induced mROS formation and apoptosis. In conclusion, mROS formation contributes significantly to visible laser irradiation-induced apoptosis via an MPT-independent pathway.

Original languageEnglish
Pages (from-to)507-516
Number of pages10
JournalJournal of Biomedical Science
Volume9
Issue number6
DOIs
StatePublished - 2002

Keywords

  • Apoptosis
  • Dihydrorhodamine-123
  • Laser scanning confocal microscopy
  • Mitochondria
  • Mitochondrial reactive oxygen species
  • Phototoxicity

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