Astrocyte MCT1 Expression Does Not Contribute to the Axonal Degenerative Phenotype Observed With Ubiquitous MCT1...

Area of Science:

• Neuroscience
• Cell Biology
• Metabolism

Background:

• Monocarboxylate Transporter 1 (MCT1) facilitates lactate and pyruvate transport, crucial for cellular energy metabolism.
• Previous studies indicated MCT1 loss in oligodendrocytes leads to age-related axonal degeneration.
• MCT1 is also expressed in astrocytes and endothelial cells, with suggested roles in cognitive functions.

Purpose of the Study:

• To investigate the role of MCT1 in astrocytes and endothelial cells in long-term axonal metabolic support and aging.
• To determine if conditional MCT1 depletion in these glial subtypes causes neurodegeneration.

Main Methods:

• Conditional null mouse models were used to deplete MCT1 specifically in astrocytes or endothelial cells.
• Inducible ubiquitous MCT1 depletion was performed to assess overall impact.
• Axonal integrity and neuronal injury were evaluated in aged mice.

Main Results:

• Conditional knockout of MCT1 in astrocytes or endothelial cells did not result in significant neuronal injury or axonal degeneration with aging.
• Inducible ubiquitous depletion of MCT1 led to late-onset axonal degeneration, similar to oligodendrocyte-specific depletion.
• Loss of astrocytic MCT1 did not induce late-onset neurodegeneration.

Conclusions:

• MCT1 in astrocytes and endothelial cells is not essential for maintaining axonal energy homeostasis during aging.
• Oligodendrocytes play a more prominent role in MCT1-mediated metabolic support of neurons compared to astrocytes and endothelial cells.
• Astrocyte MCT1 is not a critical driver of age-related axonal energy homeostasis.