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Triptans attenuate circadian responses to light
Author(s) -
Basu Priyoneel,
Ie Naomi,
Wensel Adrienne L.,
Baskerville Joelle D.,
Smith Victoria M.,
Antle Michael C.
Publication year - 2015
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.13032
Subject(s) - triptans , zolmitriptan , sumatriptan , circadian rhythm , pharmacology , suprachiasmatic nucleus , neuroscience , serotonergic , circadian clock , medicine , migraine , serotonin , chemistry , endocrinology , receptor , biology , agonist
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 5 HT 1B receptor agonists. Triptans are specific 5 HT 1B 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 5 HT 1B 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 5 HT 1B receptors on retinal terminals elsewhere in the brain, and thereby diminishing visually‐evoked neurotransmitter signalling in those areas.