Temporal changes of spinal microglia in murine models of neuropathic pain: a scoping review

Frontiers in Immunology, 2024 · DOI: 10.3389/fimmu.2024.1460072 · Published: December 6, 2024

Simple Explanation

Neuropathic pain is a chronic condition linked to changes in the central nervous system, particularly the spinal cord. This review focuses on how microglia, immune cells in the CNS, contribute to different stages of neuropathic pain development. The review examines studies using mice to model neuropathic pain, looking at how microglial changes over time relate to pain behavior. This helps understand the relationship between pain and microglial activation. The study evaluates the importance of different time points used in studies measuring chronic pain, and the relationship between pain treatments and spinal microglia and pain development.

Study Duration

Not specified

Participants

258 peer-reviewed, primary source articles

Evidence Level

Review

Key Findings

1
Most studies used inbred, young adult, male mice with peripheral nerve injury, limiting the generalizability of the data.
2
Changes in microglia and pain behavior, which were both increased, were most commonly tested up to 2 weeks after pain initiation.
3
Treatments that decrease microglia show decreased pain behavior primarily at the 1- and 2-week time point.

Research Summary

This scoping review characterizes the changes in spinal microglia over time in murine models of chronic pain. This study also evaluates the importance of the time points that different studies used to measure chronic pain and the relation of potential pain treatments to spinal microglia and pain development. Overall, this review examines the temporal changes in microglial dynamics and the relationships that exist between pain conditions and microglial activation.

Practical Implications

Study Design Improvements

Highlights the need for better clinically relevant study design considerations including the sex, age, and strain of mice included, the specific microglial markers used, the statistical tests applied, the pain models constructed, the time points assessed, and the pain tests conducted.

Longitudinal Studies

Encourages further research into studying spinal microglia dynamics in a variety of NP conditions at longer time points.

Diverse Pain Conditions

Advocates for the study of microglial changes and their influence on pain behavior in clinically observed NP conditions beyond peripheral nerve injury models.

Study Limitations

1
Generalizing analyses to all chronic pain conditions when looking at treatment effects due to low numbers of studies looking at each subclass of chronic pain models at various time points.
2
Treatments were generalized based on the microglial changes they caused in the spinal cord and not on the drug class due to the widespread heterogeneity in the treatment types.
3
Simplifications for compiling the variable data were made, including generalizing mechanical allodynia to pain behavior.

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