Melanopsin in the circadian timing system

@article{Beaule2003MelanopsinIT,
  title={Melanopsin in the circadian timing system},
  author={Christian Beaulé and Barry Robinson and Elaine Waddington Lamont and Shimon Amir},
  journal={Journal of Molecular Neuroscience},
  year={2003},
  volume={21},
  pages={73-89}
}
In mammals, circadian rhythms are generated by a light-entrainable oscillator located in the hypothalamic suprachiasmatic nucleus (SCN). Light signals reach the SCN via a dedicated retinal pathway, the retinohypothalamic tract (RHT). One question that continues to elude scientists is whether the circadian system has its own dedicated photoreceptor or photoreceptors. It is well established that conventional photoreceptors, rods and cones, are not required for circadian photoreception, suggesting… 
The circadian visual system, 2005
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References

SHOWING 1-10 OF 55 REFERENCES
Vitamin B2-based blue-light photoreceptors in the retinohypothalamic tract as the photoactive pigments for setting the circadian clock in mammals.
  • Y. Miyamoto, A. Sancar
  • Biology
    Proceedings of the National Academy of Sciences of the United States of America
  • 1998
TLDR
It is proposed that mammals have a vitamin A-based photopigment for vision and a vitamin B2-based pigment (cryptochrome) for entrainment of the circadian clock.
Melanopsin-Containing Retinal Ganglion Cells: Architecture, Projections, and Intrinsic Photosensitivity
TLDR
It is shown that melanopsin is present in cell bodies, dendrites, and proximal axonal segments of a subset of rat RGCs, most likely the visual pigment of phototransducing R GCs that set the circadian clock and initiate other non–image-forming visual functions.
Phototransduction by Retinal Ganglion Cells That Set the Circadian Clock
TLDR
It is shown that retinal ganglion cells innervating the SCN are intrinsically photosensitive, and depolarized in response to light even when all synaptic input from rods and cones was blocked.
Cryptochrome: the second photoactive pigment in the eye and its role in circadian photoreception.
  • A. Sancar
  • Biology
    Annual review of biochemistry
  • 2000
TLDR
Genetic evidence shows that cryptochromes are circadian photoreceptors in Drosophila and Arabidopsis, raising the possibility that they may be universal circadian photoresceptors, and may provide new understanding of human diseases such as seasonal affective disorder and delayed sleep phase syndrome.
Melanopsin (Opn4) Requirement for Normal Light-Induced Circadian Phase Shifting
TLDR
These mice display severely attenuated phase resetting in response to brief pulses of monochromatic light, highlighting the critical role of melanopsin in circadian photoentrainment in mammals.
Spectral sensitivity of a novel photoreceptive system mediating entrainment of mammalian circadian rhythms
TLDR
The results suggest that the photoreceptive system mediating entrainment is markedly different from that involved in visual image formation, and the reciprocal relationship between intensity and duration holds for extremely long durations.
Role of mouse cryptochrome blue-light photoreceptor in circadian photoresponses.
TLDR
Data are consistent with the hypothesis that CRY2 protein modulates circadian responses in mice and suggest that cryptochromes have a role in circadian photoreception in mammals.
Role of Melanopsin in Circadian Responses to Light
TLDR
Although melanopsin is not essential for the circadian clock to receive photic input, it contributes significantly to the magnitude of photic responses.
...
1
2
3
4
5
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