Sex‐specific differences in the circadian pattern of action potential firing by rat suprachiasmatic nucleus vasopressin neurons
Bibliographic record
Abstract
The suprachiasmatic nucleus (SCN) of the hypothalamus serves as the master circadian clock in mammals. Most SCN neurons express the inhibitory neurotransmitter GABA (gamma amino butyric acid) along with a peptide cotransmitter. Notably, the neuropeptides vasopressin (VP) and vasoactive intestinal peptide (VIP) define two prominent clusters within the SCN: those located in the ventral core (VIP) and those forming the dorsomedial "shell" of the nucleus (VP). Axons emerging from VP neurons in the shell are thought to mediate much of the SCN's output to other brain regions as well as VP release into the cerebrospinal fluid (CSF). Previous work has shown that VP release by SCN neurons is activity dependent and SCN VP neurons fire action potentials at a higher rate during the light phase. Accordingly, CSF VP levels are higher during daytime. Interestingly, the amplitude of the CSF VP rhythm is greater in males than females, suggesting the existence of sex differences in the electrical activity of SCN VP neurons. Here we investigated this hypothesis by performing cell-attached recordings from 1070 SCN VP neurons across the entire circadian cycle in both sexes of transgenic rats that express green fluorescent protein (GFP) driven by the VP gene promoter. Using an immunocytochemical approach we confirmed that >60% of SCN VP neurons display visible GFP. Recordings in acute coronal slices revealed that VP neurons display a striking circadian pattern of action potential firing, but the characteristics of this activity cycle differ in males and females. Specifically, neurons in males reached a significantly higher peak firing frequency during subjective daytime compared to females and the acrophase occurred ~1 h earlier in females. Peak firing rates in females were not significantly different at various phases of the estrous cycle.
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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".