Somatostatin varicosities contain the vesicular GABA transporter and contact orexin neurons in the hypothalamus
Bibliographic record
Abstract
Somatostatin (SST) is a neuropeptide with known inhibitory actions in the hypothalamus, where it inhibits release of growth hormone-releasing hormone (GHRH), while also influencing the sleep-wake cycle. Here we investigated in the rat whether SST neurons might additionally release GABA (gamma-aminobutyric acid) or glutamate in different regions and whether they might contact orexin neurons that play an important role in the maintenance of wakefulness. In dual-immunostained sections viewed by epifluorescence microscopy, we examined if SST varicosities were immunopositive for the vesicular transporter for GABA (VGAT) or glutamate (VGLUT2) in the posterolateral hypothalamus and neighboring arcuate nucleus and median eminence. Of the SST varicosities in the posterolateral hypothalamus, 18% were immunopositive for VGAT, whereas ≤ 1% were immunopositive for VGLUT2. In the arcuate and median eminence, 26 and 64% were VGAT+ and < 3% VGLUT2 + , respectively. In triple-immunostained sections viewed by epifluorescence and confocal microscopy, SST varicosities were seen in contact with orexin somata, and of these varicosities, a significant proportion (23%) contained VGAT along with synaptophysin, the presynaptic marker for small synaptic vesicles, and a similar proportion (25%) abutted puncta that were immunostained for gephyrin, the postsynaptic marker for GABAergic synapses. Our results indicate that a significant proportion of SST varicosities in the hypothalamus have the capacity to release GABA, to form inhibitory synapses upon orexin neurons, and accordingly through their peptide and/or amino acid, to inhibit orexin neurons, as well as GHRH neurons. Thus while regulating GHRH release, SST neurons could serve to attenuate arousal and permit progression through the sleep cycle.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".