Nicotine‐motivated behavior in <i><scp>C</scp>aenorhabditis elegans</i> requires the nicotinic acetylcholine receptor subunits <i>acr‐5</i> and <i>acr‐15</i>
Bibliographic record
Abstract
Signaling at nicotinic acetylcholine receptors in Caenorhabditis elegans controls many behaviors, including egg-laying and locomotor activity. Here, we show that C. elegans approaches a point source of nicotine in a time-, concentration- and age-dependent manner. Additionally, nicotine paired with butanone under starvation conditions prevented the reduced approach to butanone that is observed when butanone is paired with starvation alone and pairing with nicotine generates a preference for the tastes of either sodium or chloride over baseline. These results suggest nicotine acts as a rewarding substance in C. elegans. Furthermore, the nicotinic receptor antagonist mecamylamine, the smoking cessation pharmacotherapy varenicline, mutation of the dop-1 and dop-2 dopamine receptors, and mutations of either acr-5 or acr-15, two nicotinic receptor subunit genes with sequence homology to the mammalian α7 subunit, all reduced the nicotine approach behavior. These two mutants also were defective at associating the presence of nicotine with butanone under starvation conditions and acr-5 mutation could obviate the effect of pairing nicotine with salts. Furthermore, the approach deficit in acr-15 mutants was rescued by selective re-expression in a subset of neurons, but not in muscle. Caenorhabditis elegans may therefore serve as a useful model organism for nicotine-motivated behaviors that could aid in the identification of novel nicotine motivational molecular pathways and consequently the development of novel cessation aids.
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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 | 0.001 |
| 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".