Spared Nerve Injury Induces Long-Term and Brain Region-Specific Changes in Oligodendrocyte Density in Mice

Area of Science:

• Neuroscience
• Cell Biology
• Pain Research

Background:

• Non-neuronal cells, including oligodendroglia, are increasingly implicated in chronic pain.
• Chronic pain significantly alters the gene expression of oligodendroglia.
• The direct impact of chronic pain on oligodendroglial cell populations is not well understood.

Purpose of the Study:

• To investigate the long-term effects of chronic pain on oligodendrocyte precursor cells (OPC) and mature oligodendrocytes (OL).
• To determine if these effects are region-specific and sex-dependent within the brain.

Main Methods:

• Male and female mice underwent spared nerve injury (SNI) to induce chronic pain.
• Mechanical hypersensitivity was confirmed using the von Frey test.
• Immunohistochemistry was used to quantify OPC and OL in the anterior cingulate cortex (ACC), central amygdala (CeA), basolateral amygdala (BLA), and periaqueductal grey (PAG) six weeks post-surgery.

Main Results:

• Mature oligodendrocytes (OL) were reduced in the ACC and CeA, and increased in the BLA, in both sexes post-SNI.
• A sex-dependent reduction in PAG OL was observed, affecting only females.
• Oligodendrocyte precursor cells (OPC) numbers remained unchanged by SNI, though females had fewer OPC in the PAG and BLA compared to males.

Conclusions:

• Long-term chronic pain differentially impacts mature oligodendrocytes (OL) in a brain region- and sex-specific manner.
• Oligodendrocytes (OL) show lasting changes six weeks after nerve injury, highlighting their role in chronic pain pathophysiology.
• Oligodendrocyte precursor cells (OPC) are stable under chronic pain conditions, consistent with their role in maintaining homeostasis.