Related Experiment Video
Updated: Aug 17, 2026
Mitochondrial Preparation from Microglia for Glycan Analysis
Published on: May 30, 2025
Mitochondria in activated microglia in vitro
Richard B Banati1, Rupert Egensperger, Alexander Maassen
1School of Medical Radiation Sciences, and Ramaciotti Centre for Brain Imaging (Brain-Mind Research Institute), University of Sydney, East Street PO Box 170, Lidcombe NSW 1825, Australia.
Abstract:
In the CNS, microglia become activated, i.e. change their functional state and phenotype, in response to a wide variety of pathological stimuli. Since this activation is triggered at a very low threshold and at the same time remains territorially restricted, the spatial distribution of activated microglia can be used as a sensitive, generic measure of the anatomical localisation of ongoing disease processes. One protein complex, undetectable in resting microglia but highly up-regulated upon activation in vivo and in vitro, is the 'peripheral benzodiazepine binding site', as measured by binding of the isoquinoline derivate PK11195. Particularly numerous in the outer membrane of mitochondria, this binding site has also been referred to as the 'mitochondrial benzodiazepine receptor'. The de novo expression of this receptor by activated microglia suggests that the process of activation may be associated with important qualitative changes in the state of mitochondria. Here, we provide confocal light- and electron microscopic evidence that the activation of microglia indeed entails conspicuous mitochondrial alterations. In cultured rat microglia stained with the fluorescent probe, JC-1, a sensitive indicator of mitochondrial membrane potential, we demonstrate that stimulation by bacterial lipopolysaccharide and interferon-gamma increases the number of microglial mitochondrial profiles and leads to marked changes in their morphology. Prominent elongated, "needle-like" mitochondria are a characteristic feature of activated microglia in vitro. Electron microscopically, an abundance of abnormal profiles, including circular cristae or ring- and U-shaped membranes, are found. Our observations support the notion that the previously reported increase in microglial binding of PK11195, that labelled with carbon-11 ([11C] (R)-PK11195) has clinical use for the visualisation of activated microglia in vivo by positron emission tomography, may at least in part relate to an increased number and altered functional state of microglial mitochondria.
Insights
Activated microglia exhibit altered mitochondria, indicated by increased mitochondrial profiles and unique morphologies. This finding supports using [11C] (R)-PK11195 PET imaging to visualize neuroinflammation.
Area of Science:
- Neuroscience
- Cell Biology
- Immunology
Background:
- Microglia, the resident immune cells of the central nervous system (CNS), activate in response to pathological stimuli.
- Activated microglia display a distinct phenotype, including the upregulation of the peripheral benzodiazepine binding site (mitochondrial benzodiazepine receptor).
- This receptor's expression suggests potential changes in mitochondrial function during microglial activation.
Purpose of the Study:
- To investigate the mitochondrial alterations associated with microglial activation.
- To correlate these morphological changes with the expression of the peripheral benzodiazepine binding site.
Main Methods:
- Cultured rat microglia were stimulated with bacterial lipopolysaccharide and interferon-gamma.
- Confocal light microscopy using JC-1 dye assessed mitochondrial membrane potential and morphology.
- Electron microscopy examined ultrastructural changes in microglial mitochondria.
Main Results:
- Microglial activation led to an increased number of mitochondrial profiles.
- Activated microglia displayed characteristic elongated, "needle-like" mitochondria in vitro.
- Electron microscopy revealed abnormal mitochondrial structures, including circular cristae and ring-shaped membranes.
Conclusions:
- Microglial activation is associated with significant mitochondrial morphological changes.
- These mitochondrial alterations may contribute to the increased binding of PK11195 observed in activated microglia.
- The findings support the use of [11C] (R)-PK11195 positron emission tomography (PET) for in vivo imaging of neuroinflammation.
