Enhanced presynaptic mitochondrial energy production is required for memory formation

Area of Science:

• Neuroscience
• Cellular Biology
• Molecular Biology

Background:

• Long-term memory formation involves synaptic plasticity, protein synthesis, and gene expression.
• Mitochondrial function is essential for the energy demands of these memory-related processes.

Purpose of the Study:

• To investigate the role of mitochondrial respiration and dynamics in memory formation.
• To determine if context fear training enhances mitochondrial activity in specific hippocampal regions.

Main Methods:

• Measured mitochondrial oxygen consumption (OCR) in hippocampal tissue and isolated synaptosomes from trained and untrained animals.
• Utilized dynamin-related protein 1 (Drp1) inhibitors to assess its role in mitochondrial respiration and memory.

Main Results:

• Context fear training significantly increased basal, ATP synthesis-linked, and maximal OCR in the Shaffer collateral-CA1 synaptic region.
• These OCR increases were observed in synaptosomes and were dependent on Drp1.
• Drp1 inhibition impaired contextual fear memory and reduced training-associated OCR enhancement.

Conclusions:

• Context fear training enhances presynaptic mitochondrial respiration in the hippocampus.
• Drp1-mediated mitochondrial energy production in presynaptic terminals is necessary for contextual fear memory.
• This memory enhancement does not stem from increased mitochondrial number or mass within synapses.