Triptans attenuate circadian responses to light
Bibliographic record
Abstract
Daily exposure to light synchronizes the circadian clock, located in the suprachiasmatic nucleus (SCN), to external day/night cycles. These responses to light can be modified by serotonergic drugs, such as serotonin 5HT1B receptor agonists. Triptans are specific 5HT1B agonists prescribed to treat migraines. Here, we examined the effects of two triptans (zolmitriptan and sumatriptan) on photic phase resetting in Syrian hamsters. Pre-treatment with intra-SCN sumatriptan significantly attenuates, and at higher doses completely blocks, phase advances to light during the late night. Pre-treatment with systemic zolmitriptan significantly attenuates both light-induced phase advances and phase delays. Neither of these drugs, nor their vehicles, causes phase shifts on their own. Pre-treatment with zolmitriptan also significantly reduces the expression of light-induced c-fos in the SCN. Neither zolmitriptan nor vehicle alone induces significant c-fos expression in the SCN. Finally, pre-treatment with zolmitriptan does not attenuate phase shifts to intra-SCN N-methyl-d-aspartate injections, indicating that the mechanism of action for zolmitriptan is likely to be through activation of presynaptic 5HT1B receptors on retinal terminals, thereby decreasing light-induced neurotransmitter release. As triptans are commercially available medications, there is potential for their use in blocking unwanted photic phase shifting during shift-work or jet-lag. Additionally, triptans may also affect the circadian clock in patients receiving them regularly for migraines. Finally, our results may hint at the mechanism by which triptans can alleviate the photophobia that frequently accompanies migraines, namely by activating 5HT1B receptors on retinal terminals elsewhere in the brain, and thereby diminishing visually-evoked neurotransmitter signalling in those areas.
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".