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Melanopsin (Opn4) Requirement for Normal Light-Induced Circadian Phase Shifting

Science  13 Dec 2002:
Vol. 298, Issue 5601, pp. 2213-2216
DOI: 10.1126/science.1076848

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Abstract

The master circadian oscillator in the hypothalamic suprachiasmatic nucleus is entrained to the day/night cycle by retinal photoreceptors. Melanopsin (Opn4), an opsin-based photopigment, is a primary candidate for photoreceptor-mediated entrainment. To investigate the functional role of melanopsin in light resetting of the oscillator, we generated melanopsin-null mice (Opn4 −/−). These mice entrain to a light/dark cycle and do not exhibit any overt defect in circadian activity rhythms under constant darkness. However, they display severely attenuated phase resetting in response to brief pulses of monochromatic light, highlighting the critical role of melanopsin in circadian photoentrainment in mammals.

  • * To whom correspondence should be addressed. E-mail: stevek{at}scripps.edu, provenci{at}bob.usuhs.mil

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