The mechanisms of protease-activated receptor 2 in mediating pain behaviors through nonselective cation channel signaling
Bibliographic record
Abstract
Abstract Background: Activation of purinergic receptor P2X ligand-gated ion channel 3 (P2X3), transient receptor potential vanilloid type 1 (TRPV1), and transient receptor potential ankyrin 1 (TRPA1) by their specific ligands is a major mechanism contributing to magnified pain responses. The relationship between these nonselective cation channels and proteinase-activated receptor 2 (PAR2) activation mediated pain is still to be clarified.Methods: In this study, both in vitro model of dorsal root ganglion (DRG) neurons with PAR2 agonist SL-NH2 challenge and SL-NH2-induced pain rat model were used to approach these questions. The expression of P2X3, TRPV1, and TRPA1 in DRG neurons was investigated by quantitative real-time RT-PCR, Western blot, and immunofluorescence. The involvement of the PLCβ3/PKCε signaling pathway was also determined. The behavior test for mechanical allodynia and thermal hyperalgesia was performed. Results: SL-NH2 induced upregulation of P2X3, TRPV1, and TRPA1 through phosphorylation of phospholipase Cβ3 (PLCβ3) and protein kinase Cε (PKCε) signaling pathway in DRG neurons in vitro and in vivo. SL-NH2 also elevated the proportion of P2X3-, TRPV1-, and TRPA1-expressing neurons. The upregulation of P2X3, TRPV1, and TRPA1 and phosphorylation of PLCβ3 and PKCε in DRG neurons was paralleled with mechanical allodynia and thermal hyperalgesia behaviors in rats. Conclusions: The data of the present study imply that SL-NH2 as a noxious stimulus activates PAR2 which induces TRPV1, TRPA1, and P2X3 upregulation through PLCβ3/PKCε signaling pathway, thereby decreasing activation thresholds and increasing excitability, resulting in sustained nociceptive activity in DRG neurons, and then causing mechanical allodynia and thermal hyperalgesia behaviors. These data expanded our knowledge about PAR2-mediated pain sensitivity and its relationship with TRPV1, TRPA1, and P2X3 and provided new opportunities on management of pain behaviors.
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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) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".