3065 - High-Dose Ionizing Radiation Induces Mitochondrial Dysfunction, Mitophagy, Apoptosis, and Synaptic Plasticity Loss in Cultured Primary Rat Cortical Neurons

05:00pm - 06:00pm PT

Hall F

Screen: 22

POSTER

Presenter(s)

Sheng-Yow Ho, MD, MS - Chi Mei Medical Center , Tainan, Tainan city

S. Y. Ho¹, C. P. Chang², W. P. Liu², C. H. Lin¹, and L. T. Shieh³; ¹Department of Radiation Oncology, Chi Mei Medical Center, Tainan, Taiwan, ²Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan, ³Department of Radiation Oncology, Chi Mei Medical Center, Liouying, Tainan, Taiwan

Purpose/Objective(s):

Ionizing radiation can cause significant neurotoxicity by disrupting mitochondrial function, inducing mitophagy/autophagy, promoting apoptosis, and impairing synaptic integrity. However, the specific molecular mechanisms by which high-dose radiation exerts these effects in neurons remain to be elucidated.

Materials/Methods:

Primary cortical neurons were exposed to 30 Gy radiation in vitro. Mitochondrial membrane potential (MMP) was assessed via JC-1 staining. Protein levels of mitophagy-related markers (FIS-1, Parkin, and Mitofusion-1), autophagy markers (LC3B and p62), and apoptosis marker (caspase-3) were analyzed by Western blot. ATP levels were quantified using an oxidative phosphorylation assay, and cell viability was determined using a cell counting kit assay. Mitochondrial morphology was examined by transmission electron microscopy (TEM) with immunogold labeling for Mitofusion-1 (10 nm) and FIS-1 (18 nm). Synaptic plasticity was evaluated via immunofluorescence staining for NeuN (in combination with DAPI).

Results:

Exposure to radiation significantly reduced MMP and ATP production, accompanied by decreased cell viability. Western blot analysis revealed elevated FIS-1 and Parkin expression, along with reduced Mitofusion-1, indicating enhanced mitophagy and mitochondrial fragmentation. Increased LC3B levels and reduced p62 suggested activation of autophagic processes. Moreover, caspase-3 levels were significantly elevated, indicating heightened apoptosis in irradiated neurons. TEM imaging confirmed marked mitochondrial structural abnormalities (reduced Mitofusion-1 and increased FIS-1 labeling). Immunofluorescence analysis demonstrated diminished NeuN expression, reflecting compromised synaptic plasticity.

Conclusion:

These findings demonstrate that high-dose (30 Gy) radiation induces mitochondrial dysfunction, elevates mitophagy/autophagy and apoptotic markers, and impairs synaptic plasticity in primary cortical neurons. Targeting these pathways may provide novel therapeutic strategies to alleviate radiation-induced neurotoxicity.