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Back Mechanical Sensitivity Assessment in the Rat for Mechanistic Investigation of Chronic Back Pain
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Somatosensory behavioral alterations in a NGF-induced persistent low back pain model
Nicholas R Reed1, William R Reed2, Michael Syrett1
1Saint Louis University School of Medicine, 1402 South Grand Blvd. Saint Louis, MO, 63104, USA.
Behavioural Brain Research
|October 4, 2021
Summary
This study shows that nerve growth factor (NGF) injections in male rats cause localized low back pain (LBP) hypersensitivity, primarily in the trunk, unlike previous findings in female rats.
Area of Science:
- Neuroscience
- Pain Research
- Animal Models
Background:
- Low back pain (LBP) is a significant global health issue with poorly understood mechanisms.
- A novel rat model for LBP using nerve growth factor (NGF) injections has been developed.
- Further characterization of somatosensory alterations in this NGF-induced LBP model is needed.
Purpose of the Study:
- To characterize the time-dependent development of mechanical hypersensitivity in a male rat model of NGF-induced LBP.
- To investigate local and remote somatosensory changes following NGF injections.
- To compare findings in male rats with previous studies in female rats.
Main Methods:
- Adult male Sprague-Dawley rats received two NGF or control injections into trunk musculature.
- Behavioral assays including von Frey filaments and a small animal algometer were used.
- Testing occurred at multiple time points from baseline to 14 days post-injection.
Main Results:
- NGF-injected rats exhibited increased ipsilateral trunk cutaneous mechanical sensitivity from Day 7 to Day 14.
- Ipsilateral deep trunk mechanical hyperalgesia was observed from Day 2 to Day 14 in NGF rats.
- Cutaneous hypersensitivity onset was delayed compared to deep hyperalgesia.
Conclusions:
- Mechanical somatosensory changes in male rats with NGF-induced LBP are predominantly localized to the ipsilateral trunk.
- These findings contrast with more widespread hypersensitivity reported in female rats using the same model.
- Future research should explore sex-based differences in pain behavior within this LBP model.
