Critical Role of Mitochondrial Reactive Oxygen Species Formation in Visible Laser Irradiation-Induced Apoptosis in Rat Brain Astrocytes (RBA-1)

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, MitoTracker 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.

Reactive Oxygen Species-Dependent c-Fos/Activator Protein 1 Induction Upregulates Heme Oxygenase-1 Expression by Bradykinin in Brain Astrocytes

“…Despite an obviously important role of BK or related peptides in brain diseases, the processes by which BK was implicated in astrocytic functions are not completely understood. Thus, we used a well-established rat astroglial cell line RBA-1 cells (27) to investigate the mechanisms underlying BK-induced HO-1 expression and its activity. Our results suggest that in RBA-1 cells, activation of ROS-dependent JNK/c-Jun and ERK/ NF-kB pathways leading to induction of c-Fos/AP-1, mediated through a B 2 BKR, is essential for BK-induced HO-1 gene expression and its activity.…”

“…This cell line originated from a primary astrocyte culture of neonatal rat cerebrum and was naturally developed through successive cell passages (27). Cells were cultured and treated as previously described (24).…”

In vitro effect of carboplatin, cytarabine, paclitaxel, vincristine, and low‐power laser irradiation on murine mesenchymal stem cells

“…Vincristine and carboplatin display their effect partly via mitochondrial pathway and LPLI can cause increased mitochondrial respiration. Cytarabine generate reactive oxygen species, while laser-inducible reactive oxygen species can mediate laser's effect on cells [36][37][38][39][40]. Protein kinase C is thought to help acquire multidrug resistance.…”

Melatonin and mitochondrial function

“…In laser-irradiated cells, the level of ROS in the mitochondrial compartment was found to be higher than in other parts of the cell. Treatment with the antioxidants melatonin and vitamin E largely attenuated mitochondrial ROS formation and prevented apoptosis, indicating that mitochondrial ROS contribute significantly to laser irradiation-induced apoptosis via an MPT-independent pathway (Jou et al, 2002).…”