5‐HT<sub>4</sub> receptors exert a frequency‐related facilitatory control on dorsal raphé nucleus 5‐HT neuronal activity
Bibliographic record
Abstract
We investigated, using single-unit recordings in chloral hydrate-anaesthetized rats, the role of serotonin 4 (5-HT4) receptors in the control of dorsal raphé nucleus (DRN) 5-HT neuron activity. About one-half (36) of the 76 neurons recorded were affected by either the preferential 5-HT4 agonist cisapride (500 and 1000 micro g/kg, i.v.) or the selective 5-HT4 antagonist, GR 125487 (200- 2000 micro g/kg, i.v.). Responding neurons displayed a significantly higher mean basal firing rate (1.93 +/- 0.1 Hz) than non-responders (1.31 +/- 0.1 Hz). The firing rate of responding 5-HT neurons was enhanced dose-dependently by cisapride (+47 and +94% at 500 and 1000 micro g/kg, respectively), an effect abolished by GR 125487 (500 micro g/kg) and reduced by the 5-HT4 antagonist, SDZ 205557 (500 micro g/kg, i.v). Conversely, GR 125487 induced a dose-dependent inhibition of responders activity, which was almost completely suppressed at the dose of 2000 micro g/kg. In a separate set of experiments, the selective 5-HT4 agonist, prucalopride (500 micro g/kg, i.v), increased the firing activity (+35%) of 5-HT neurons displaying a high basal firing rate; subsequent injection of GR 125487 (500 micro g/kg, i.v.) suppressed this effect. These results indicate that 5-HT4 receptors exert both a tonic and a phasic, positive, frequency-related control on DRN 5-HT neuronal activity. The existence of such a control might open new avenues for therapeutic research in the antidepressant field.
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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".