Somatodendritic localization of 5-HT1A and preterminal axonal localization of 5-HT1B serotonin receptors in adult rat brain
Bibliographic record
Abstract
The 5-HT1A and 5-HT1B receptors of serotonin play important roles as auto- and heteroreceptors controlling the release of serotonin itself and of other neurotransmitters/modulators in the central nervous system (CNS). To determine the precise localization of these receptors, we examined their respective cellular and subcellular distributions in the nucleus raphe dorsalis and hippocampal formation (5-HT1A) and in the globus pallidus and substantia nigra (5-HT1B), using light and electron microscopic immunocytochemistry with specific antibodies. Both immunogold and immunoperoxidase preembedding labelings were achieved. In the nucleus raphe dorsalis, 5-HT1A immunoreactivity was found exclusively on neuronal cell bodies and dendrites, and mostly along extrasynaptic portions of their plasma membrane. After immunogold labeling, the density of membrane-associated 5-HT1A receptors could be estimated to be at least 30–40 times that in the cytoplasm. In the hippocampal formation, the somata as well as dendrites of pyramidal and granule cells displayed 5-HT1A immunoreactivity, which was also prominent on the dendritic spines of pyramidal cells. In both substantia nigra and globus pallidus, 5-HT1B receptors were preferentially associated with the membrane of fine, unmyelinated, preterminal axons, and were not found on axon terminals. A selective localization to the cytoplasm of endothelial cells of microvessels was also observed. Because the 5-HT1A receptors are somatodendritic, they are ideally situated to mediate serotonin effects on neuronal firing, both as auto- and as heteroreceptors. The localization of 5-HT1B receptors to the membrane of preterminal axons suggests that they control transmitter release from nonserotonin as well as serotonin neurons by mediating serotonin effects on axonal conduction. The fact that these two receptor subtypes predominate at extrasynaptic and nonsynaptic sites provides further evidence for diffuse serotonin transmission in the CNS. J. Comp. Neurol. 417:181–194, 2000. ©2000 Wiley-Liss, Inc.
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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 | 0.001 | 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) | 0.002 | 0.001 |
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".