EurekaMag.com logo
+ Site Statistics
References:
52,725,316
Abstracts:
28,411,598
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

The circadian clock, light/dark cycle and melatonin are differentially involved in the expression of daily and photoperiodic variations in mt(1) melatonin receptors in the Siberian and Syrian hamsters


Neuroendocrinology 74(1): 55-68
The circadian clock, light/dark cycle and melatonin are differentially involved in the expression of daily and photoperiodic variations in mt(1) melatonin receptors in the Siberian and Syrian hamsters
Mechanisms underlying the daily and photoperiodic variations in mt(1) melatonin receptors were investigated in the pars tuberalis (PT) and suprachiasmatic nuclei (SCN) of Siberian and Syrian hamsters. Whatever its daily profile, melatonin receptor density was strongly increased in both structures and species after constant light exposure or pinealectomy, and decreased after a single melatonin injection, indicating melatonin involvement in the daily regulation of the receptor protein. This was confirmed by a strong inverse correlation between melatonin binding capacity and plasma melatonin concentration. In contrast, regulation of mt(1) mRNA appeared more complex. The circadian clock, the light/dark cycle and melatonin are all implicated in mt(1) gene daily fluctuations, but the extent of their involvement depends upon the structure and the species studied. The photoperiodic decrease in melatonin receptor density observed in short photoperiod (PT of the two hamster species and Syrian hamster SCN) seems to be the consequence of a long-term mt(1) gene repression induced by the lengthening of the melatonin peak. Altogether, these results show that during daily variations, mt(1) melatonin receptor mRNA and protein are differentially regulated, while at the photoperiodic level, the mt(1) protein status depends on mRNA transcription.


Accession: 011482892

PMID: 11435758

DOI: 54670



Related references

Twice daily melatonin peaks in Siberian but not Syrian hamsters under 24 h light:dark:light:dark cycles. Chronobiology International 29(9): 1206-1215, 2013

Melatonin and the circadian clock in mink: Effects of daily injections of melatonin on circadian rhythm of locomotor activity and autoradiographic localization of melatonin binding sites. Journal of Neuroendocrinology 5(3): 241-246, 1993

Melatonin and the circadian clock in mink: effects of daily injections of melatonin on circadian rhythm of locomotor activity and autoradiographic localization of melatonin binding sites. Journal of Neuroendocrinology 5(3): 241-246, 1993

Acute melatonin treatment alters dendritic morphology and circadian clock gene expression in the hippocampus of Siberian hamsters. Hippocampus 25(2): 142-148, 2015

Melatonin accelerates reentrainment after phase advance of the light-dark cycle in Syrian hamsters: antagonism by flumazenil. Chronobiology International 10(6): 435-441, 1993

In old hamsters a melatonin-agonist accelerates adaptation of circadian rhythmicity to a shift in the light-dark cycle. Society for Neuroscience Abstracts 24(1-2): 698, 1998

A melatonin agonist facilitates circadian resynchronization in old hamsters after abrupt shifts in the light-dark cycle. Brain Research 880(1-2): 207-211, 13 October, 2000

The photoperiodic response in Syrian hamsters depends upon a melatonin-driven rhythm of sensitivity to melatonin. Biological Signals 6(4-6): 264-271, 1997

Melatonin desensitizes endogenous MT2 melatonin receptors in the rat suprachiasmatic nucleus: relevance for defining the periods of sensitivity of the mammalian circadian clock to melatonin. Faseb Journal 18(14): 1646-1656, 2004

Circadian pattern in the anti gonadal action of melatonin in syrian hamsters exposed to continuous illumination or 20 hours light 4 hours dark. Transactions of the Kansas Academy of Science 83(3): 148-149, 1980