Assessing Susceptibility to Carbon Dioxide Gas in Three Rat Strains Using the Loss of Righting Reflex
Bibliographic record
Abstract
Abstract Overdose of carbon dioxide gas (CO 2 ) is a common euthanasia method for rodents; however, CO 2 exposure activates nociceptors in rats at concentrations equal to or greater than 37% and is reported to be painful in humans at concentrations equal to or greater than 32.5%. Exposure of rats to CO 2 could cause pain before loss of consciousness. We used 2 standardized loss of righting reflex (LORR) methods to identify CO 2 concentrations associated with unconsciousness in Wistar, Long–Evans, and Sprague–Dawley rats ( n = 28 animals per strain). A rotating, motorized cylinder was used to test LORR while the rat was being exposed to increasing concentrations of CO 2 . LORR was defined based on a 15-second observation period. The 2 methods were 1) a 1-Paw assessment (the righting reflex was considered to be present if one or more paws contacted the cylinder after the rat was positioned in dorsal recumbency), and 2) a 4-Paw assessment (the righting reflex was considered to be present if all 4 paws contacted the cylinder after the rat was positioned in dorsal recumbency). Data were analyzed with Probit regression, and dose-response curves were plotted. 1-Paw EC 95 values (CO 2 concentration at which LORR occurred for 95% of the population) were Wistar, 27.2%; Long–Evans, 29.2%; and Sprague–Dawley, 35.0%. 4-Paw EC 95 values were Wistar, 26.2%; Long–Evans, 25.9%, and Sprague–Dawley, 31.1%. Sprague–Dawley EC 95 values were significantly higher in both 1- and 4-Paw tests as compared with Wistar and Long–Evans rats. No differences were detected between sexes for any strain. The 1-Paw EC 95 was significantly higher than the 4-Paw EC 95 only for Sprague-Dawley rats. These results suggest that a low number of individual rats from the strains studied may experience pain during CO 2 euthanasia.
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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 | 0.004 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.003 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| 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".