Involvement of Tuberomamillary Histaminergic Neurons in Isoflurane Anesthesia
Bibliographic record
Abstract
BACKGROUND: The brain histaminergic system plays a critical role in maintenance of arousal. Previous studies suggest that histaminergic neurotransmission might be a potential mediator of general anesthetic actions. However, it is not clear whether histaminergic tuberomamillary nucleus (TMN) is necessarily involved in the sedative/hypnotic effects of general anesthetics. METHODS: Male Long Evans rats underwent either TMN orexin-saporin/sham lesion or implantation of intracerebroventricular cannula 2 weeks before the experiment. The behavioral endpoint of loss of righting reflex was used to assess the hypnotic property of isoflurane, propofol, pentobarbital, and ketamine in animals. Histaminergic cell loss was assessed by adenosine deaminase expression in the TMN using immunohistochemistry. RESULTS: Rats with bilateral TMN orexin-saporin lesion induced an average 72% loss of histaminergic cells compared with sham-lesion rats. TMN orexin-saporin lesion or intracerebroventricular administration of triprolidine (an H1 receptor antagonist) decreased the 50% effective concentration for loss of righting reflex value and prolonged emergence time to isoflurane anesthesia. However, TMN orexin-saporin lesion had no significant effect on the anesthetic sensitivity to propofol, pentobarbital, and ketamine. CONCLUSIONS: These findings suggest a role of the TMN histaminergic neurons in modulating isoflurane anesthesia and that the neural circuits for isoflurane-induced hypnosis may differ from those of γ-aminobutyric acid-mediated anesthetics and ketamine.
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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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".