A27 THE SUSTAINED ANTINOCICEPTIVE EFFECT OF ENDOGENOUS OPIOIDS IN PRECLINICAL MODEL OF IBD IS MEDIATED BY COMPARTMENTALIZED ENDOSOMAL SIGNALING BY DELTA OPIOID RECEPTORS
Bibliographic record
Abstract
Endogenous opioids released from CD4+T cells are increased in inflammatory bowel disease patients (IBD) and pre-clinical models of IBD, and have an important analgesic effect. We have shown that endogenous opioids in supernatant from cDSS mice have an antinociceptive action on dorsal root ganglia (DRG) neurons that is mediated by δ (DOR) and μ (MOR) opioid receptors. We also found that acute application of opioids for minutes had an unexpectedly sustained analgesic effect but the mechanism was unclear. We hypothesized that endogenous opioids have a sustained antinociceptive effect on nociceptors via endosomal signaling. Chronic colitis was induced with 2% dextran sulfate sodium (DSS; three cycles: 5 days of DSS/5 days of water) in C57BL/6 mice and colonic supernatants were collected. DRG neurons were exposed to control or cDSS supernatants (1h), or opioid agonists (10nM, 15min); DAMGO (MOR-selective) or DADLE (DOR-selective). We recorded changes in rheobase (minimum current to fire action potential) by perforated patch-clamp, immediately after washout of drugs (T0) or 30 min later (T30). We used Förster resonance energy transfer (FRET) biosensors to examine signaling (protein kinase C; PKC and extracellular signal-regulated kinase; ERK) in subcellular compartments mediated by DOR agonists: DADLE and SNC80 (100nM). DRG neurons from DOR-eGFP mice were nucleofected with FRET sensors. Neurons were pre-treated with dynamin GTPase (50 μM dyngo4a) or clathrin inhibitor, (15 μM pistop2) for 30 min prior to agonists. One or Two way ANOVA and post hoc Tukey’s tests were used to analyze the data. Supernatant from cDSS mice had a sustained antinociceptive effect on neuronal excitability (increased rheobase 39.6%, p<0.05 %). Similarly, DADLE increased the rheobase at time 0 and T30 compared to control (27.4% and 38.2%, p<0.01) whereas DAMGO had no sustained effect. The clathrin inhibitor Pistop2, which inhibits receptor endocytosis, blocked the sustained antinociceptive effect (T30) of cDSS supernatant and DADLE, but did not affect the immediate response (T0). FRET assay showed that SNC80 and DADLE induced sustained activity at the plasma membrane and cytosolic PKC and cytosolic and nuclear ERK activity. The endocytosis inhibitor, dyngo4a, blocked SNC80-induced cytosolic PKC and nuclear ERK activity, but did not affect cytosolic ERK. Endogenous opioids in this preclinical IBD model and DOR agonists have a sustained antinociceptive action. This effect is dependent on endosomal signaling, activating PKC and ERK in subcellular compartments, and could provide a novel therapeutic target to treat pain in IBD. CCC
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".