Effect of Conditioned Pain Modulation on Somatosensory Profile in Surgical Models of Osteoarthritis Pain in Rats and Dogs
Bibliographic record
Abstract
Introduction: The objective was to compare the effect of conditioning stimulus (CS) on somatosensory changes in animal models of osteoarthritis (OA) pain. Materials and Methods: OA model was surgically induced in right hind stifle at day (D) 0. Rats ( n = 48/Sprague-Dawley/female/ovariectomized–OVX–) were divided in four groups: OA-OVX placebo/ OA-OVX positive analgesic–PA–: pregabalin; oral; 30 mg/kg and carprofen; subcutaneous; 5 mg/kg/naïve-OVX/naïve-normal. OA-dogs ( n = 6/sterilized: female = 4; male = 2) received a placebo. Quantitative sensory testing (QST) included punctate tactile (rats; paw withdrawal threshold (PWT); D–1; D7; D14; D21; D35; D49: D56) and mechanical (dogs; D–1, week–W–4; W7; W9) allodynia evaluation, pre- and post-CS. Mixed model and Student’s t tests were applied (α = 0.05). Results: Dynamic CS increased QST (D–1) threshold in rats ( p < 0.023), but not in dogs ( p > 0.922). Secondary allodynia (ipsilateral) was noted in OA rats (D7; p < 0.035) and in placebo group (D7-D56). CS increased PWT in placebo group, corresponding to an efficient conditioning pain modulation (CPM) (D21; D35; p > 0.107). Central sensitization (contralateral) was observed in placebo rats compared with PA (D14) and all other groups (D56); p < 0.004. The post-CS contralateral PWT increase counteracted the secondary allodynia present pre-CS ( p > 0.062). An efficient CPM effect was observed for all time-points in PA and placebo OA rats. Primary allodynia was present in OA dogs at W4 with a nadir at W7; p = 0.038 without a CPM effect. Discussion: OA animals developed allodynia, supporting peripheral and central sensitization. Post-CS response was variable in rats within time, supporting a possible fatigue in CPM (activation–alteration). In laboratory dogs, the stress-induced analgesia (baseline) complexified the CPM manifestation. Acknowledgements: The authors would like to thank ArthroLab’s personnel for their technical assistance. There was not proprietary interest or funding provided for this project. Dr. Beatriz Monteiro is a recipient of the Vanier Canada Graduate Scholarship.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| 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".