Serotonin Induces Tonic Firing in Layer V Pyramidal Neurons of Rat Prefrontal Cortex during Postnatal Development
Bibliographic record
Abstract
The effects of serotonin (5-HT) on neuronal activity were examined during postnatal development in layer V pyramidal neurons of the rat prefrontal cortex (PFC) in vitro. Whole-cell patch-clamp recordings were made in slices obtained from rats aged between postnatal day (P) 6 and P31. In P14 or younger neurons, bath application of 5-HT (10 microM) induced a large depolarization followed by tonic firing at 2-5 Hz. The excitatory effects of 5-HT decreased rapidly after P14, so that by P21, 5-HT produced a small depolarization or hyperpolarization without cell firing. The excitatory effects of 5-HT at younger ages were attributed to 5-HT2A receptors because the effects were mimicked by the 5-HT2 agonist alpha-methyl-5-HT but not by the 5-HT3 agonist 1-(m-chlorophenyl)-biguanide, nor by the 5-HT2B/2C agonist 1-(3-chlorophenyl)piperazine, and were blocked by the 5-HT2A antagonists ketanserin and alpha-phenyl-1-(2-phenylethyl)-4-piperidinemethanol. The excitatory responses persisted in 0 [Ca2+]o and high [Mg2+]o in the presence of TTX or blockers of ionotropic glutamate receptors, suggesting that the effects were mediated essentially by postsynaptic mechanisms. The responses to 5-HT involve a reduction of K+ conductance and an enhancement of the hyperpolarization-activated Na+/K+ current. The developmental decline of 5-HT-induced excitatory effects was associated with a downregulation of 5-HT2A receptor function and a decrease in the input resistance during early life. These results suggest that 5-HT is an important regulator of neuronal activity in the neonatal PFC and may play a role in activity-dependent developmental processes.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".