Increased mitochondrial volume in dentate hilar microglia after kainic acid-induced seizures

Abstract

Seizures trigger rapid microglial responses in the hippocampus, but the accompanying organelle-level changes remain poorly understood. Since mitochondria regulate cellular metabolism and stress signaling, we examined whether kainic acid (KA)-induced seizures alter mitochondrial volume and subcellular localization in hippocampal microglia. Microglial mitochondria were labeled in Cx3cr1-CreERT2;Rosa26-LSL-mitoGFP mice by tamoxifen administration. Twenty-four hours after KA injection, microglia in the dentate hilus, a region within the dentate gyrus relevant to seizure pathology, were analyzed by confocal microscopy and three-dimensional reconstruction. Compared with control mice, KA-treated mice showed increased total mitochondrial volume in dentate hilar microglia without a significant change in microglial volume. This increase was evident in the cell body and nucleus-contacting mitochondrial compartments, whereas process-associated mitochondrial volume was not significantly changed. These findings indicate that KA-induced seizures are accompanied by increased mitochondrial volume in dentate hilar microglia.