Spinal Autofluorescent Flavoprotein Imaging in a Rat Model of Nerve Injury-Induced Pain and the Effect of Spinal Cord Stimulation

PLoS ONE, 2014 · DOI: 10.1371/journal.pone.0109029 · Published: October 3, 2014

Neurology Pain Management Medical Imaging

Simple Explanation

Nerve injury can lead to neuropathic pain, characterized by heightened sensitivity of spinal cord neurons. This study investigates how spinal cord stimulation (SCS) affects metabolic activity in the spinal dorsal horn, which is linked to pain processing. The researchers used Autofluorescent Flavoprotein Imaging (AFI) to visualize changes in spinal metabolic activity in a rat model of nerve injury-induced pain. AFI allows for high-resolution monitoring of neuronal metabolic activity. The study found that neuropathic rats showed an AFI response to non-painful touch, unlike healthy rats. SCS also caused an immediate reduction in spinal metabolic activity in neuropathic rats.

Study Duration

Not specified

Participants

18 young adult male Sprague Dawley rats, 20 Wistar rats

Evidence Level

Not specified

Key Findings

1
Neuropathic rats demonstrated an AFI-response to palpation, while naı¨ve rats did not.
2
An immediate, short-lasting, but strong reduction in AFI intensity and area of excitation occurred following SCS, but not following sham stimulation.
3
AFI can be used to directly visualize changes in spinal metabolic activity following nerve injury.

Research Summary

This study uses Autofluorescent Flavoprotein Imaging (AFI) to examine changes in spinal dorsal horn metabolic activity in a rat model of nerve-injury induced pain (Seltzer model) and the effect of spinal cord stimulation (SCS). The study found that neuropathic rats showed an AFI response to palpation, unlike healthy rats. SCS also caused an immediate reduction in spinal metabolic activity in neuropathic rats. The data confirm that AFI can be used to directly visualize changes in spinal metabolic activity following nerve injury and they imply that SCS acts through rapid modulation of nociceptive processing at the spinal level.

Practical Implications

Understanding Neuropathic Pain Mechanisms

The study highlights the role of altered spinal cord processing in neuropathic pain, specifically the increased response to non-noxious stimuli.

SCS Mechanism of Action

The findings suggest that SCS acts by rapidly modulating nociceptive processing at the spinal level, providing a direct visualization of its effects.

AFI as a Research Tool

The study demonstrates the utility of AFI for visualizing and studying spinal metabolic activity changes in the context of pain and neuromodulation.

Study Limitations

1
AFI does not allow imaging of deep structures like the deep dorsal horn of the spinal cord and has a relatively low signal-to-noise ratio
2
The effect of SCS on nociceptive activity in the superficial dorsal horn that we describe here is rather short lasting
3
Continuous stimulation during AFI recording was not feasible due to our experimental setup, as the spinal electrode prevented imaging of the spinal cord.

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