Examining Mitochondrial Morphology in Mouse Brains

Mitochondria are dynamic organelles that rely on a balance of opposing fission and fusion events to sustain mitochondrial function and efficiently meet the energy demands of a cell. As high-energy demanding cells, neurons rely heavily on optimally functional mitochondria with balanced mitochondrial dynamics, to ensure a sufficient energy supply required to maintain cell survival, establish membrane excitability and partake in processes of neurotransmission and plasticity. As such, many neurodegenerative diseases (e.g., Alzheimer’s disease, Parkinson’s disease) and stress conditions (e.g., stroke) leading to neuronal dysfunction or death are often associated with impaired mitochondrial function and dynamics, characterized by excessive mitochondrial fragmentation. For this reason, the assessment of mitochondrial morphology in neurons and within the brain can provide valuable information. The dynamic nature of mitochondria is not only observed in shape changes, but also changes in mitochondrial network connectivity and in cristae architecture. In this chapter, we will describe how mitochondrial morphology can be examined in vitro using hippocampal neuronal cultures and in vivo using mouse brain sections by immunocytochemistry, immunohistochemistry, and electron microscopy techniques.