Time-dependent effects of hypoxia on mitochondrial dynamics, dysfunction and apoptosis in C8-D1A astrocytes

This study aimed to investigate the effects of hypoxia on mitochondrial function in C8-D1A astrocytes and to evaluate its association with apoptosis. Mouse C8-D1A astrocytes were allocated to a normoxia group (21 % O₂, 5 % CO₂, 37 °C) or a hypoxia group (1 % O₂, 5 % CO₂, 37 °C) and cultured for 24 h, 48 h, or 72 h. Compared with the normoxia group, the hypoxia group demonstrated a significant reduction in mean mitochondrial fluorescence intensity (p < 0.01) and a significant increase in mitochondrial ROS levels. Regarding mitochondrial dynamics-related proteins, Mfn1 expression was significantly decreased, and Mfn2 expression was significantly decreased at 72 h (p < 0.01). Drp1 expression was significantly increased at all time points (p < 0.01), and Fis1 expression was significantly upregulated (p < 0.01). The proportion of cells exhibiting reduced mitochondrial membrane potential was significantly higher in the hypoxia group. The percentage of apoptotic cells was significantly increased. TEM analysis revealed structural abnormalities of mitochondria in cells exposed to hypoxia. Hypoxia may promote apoptosis in C8-D1A astrocytes through disruption of mitochondrial morphology, function, and dynamics. These alterations are associated with decreased mitochondrial content and increased ROS production, which may contribute to mitochondrial dysfunction and apoptosis under hypoxic conditions.