Elsevier

Brain Research

Volume 694, Issues 1–2, 2 October 1995, Pages 183-190
Brain Research

Research report
Circadian rhythms in mice can be regulated by photoreceptors with cone-like characteristics

https://doi.org/10.1016/0006-8993(95)00694-LGet rights and content

Abstract

In this report we have characterized the photopigments mediating circadian phase shifts in retinal degenerate (rd) mice. In aged rdrd mice, which lack detectable opsin, high performance liquid chromatography (HPLC) was used to quantify the photopigment chromophore 11-cis-retinaldehyde. This chromophore was photoisomerized in whole eyes, suggesting the presence of a functional opsin-based photopigment system. We also analyzed the spectral sensitivity of phase shifting circadian locomotor rhythms. Our data implicate a photopigment that is consistent with the involvement of the middle wavelength-sensitive cone photoreceptors (M-cones; Λmax = 511 nm) found in the mouse retina. In addition, discrete near-ultraviolet (UV-A) pulses were capable of eliciting large phase shifts in circadian locomotor activity rhythms. This result is consistent with the involvement of the short wavelength-sensitive cone photoreceptors (UV-cones; Λmax = 359 nm) in photoentrainment. Collectively, these data suggest that both cone classes of the mouse may mediate the photic regulation of circadian rhythms. If this is the case, circadian sensitivity can be maintained by very few degenerate cones. Alternatively, an unknown class of ocular photoreceptor may fulfill this function.

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  • Cited by (0)

    1

    Department of Anatomy, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814-4799, USA.

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