Anatomical specificity of acidic saline model of chronic pain and the role of glia
Bibliographic record
Abstract
Research into the mechanisms of hyperalgesia is ongoing with the goal of improving clinical management of chronic pain. One animal model of chronic musculoskeletal pain uses two injections of acidic saline into a lateral gastrocnemius muscle to induce a long-lasting bilateral decrease in paw withdrawal thresholds. This study tested whether the two injections need to occur in the same muscle. Male Sprague-Dawley rats were injected with acidic saline (pH 4.0) in either the lateral or medial head of gastrocnemius or the contralateral gastrocnemius (lateral head). All animals received a second injection in the ipsilateral gastrocnemius (lateral head). Mechanical withdrawal thresholds were reduced in all groups when tested 24 hours after the second injection. Animals in which the first muscle injection was substituted with a non-specific treatment (intraperitoneal injection of lipopolysaccharide) developed bilateral hyperalgesia after a single acidic saline injection. Thus, the mechanism of hyperalgesia in this model is not restricted to the injected tissues and may include central nervous system structures. Consistent with this, an inhibitor of glia cell activation (minocycline) blocked the development of bilateral hyperalgesia. These data indicate that the central nervous system may play a large role in mediating chronic musculoskeletal pain.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".