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Author Notes:

Correspondence should be addressed to Dr. P. Michael Iuvone, 1365 B Clifton Road, Clinic B, Room B5601, Atlanta, GA 30322.miuvone@emory.edu

Author contributions: C.K.H., S.S.C., C.R.J., and P.M.I. designed research

C.K.H., S.S.C., and C.R.J. performed research

G.C.-K.C. and D.R.S. contributed unpublished reagents/analytic tools

C.K.H. and P.M.I. analyzed data

C.K.H. and P.M.I. wrote the paper.

The authors thank Urs Albrecht and Juergen Ripperger for providing expression vectors for BMAL1 and NPAS2; Steven McKnight and Carol Dudley for providing retinas of Npas2−/− mice for initial pilot experiments; John Dowling for providing constructive critiques of the manuscript.


Research Funding:

This study was supported by Grants R01 EY004864, R01 NS020498, F31 EY021089, T32 EY007092, and T32 GM008602 from the National Institutes of Health, and an unrestricted departmental grant from Research to Prevent Blindness (RPB).

P.M.I. is the recipient of a Senior Scientific Investigator Award from RPB.

Circadian Rhythm of Contrast Sensitivity Is Regulated by a Dopamine-Neuronal PAS-Domain Protein 2-Adenylyl Cyclase 1 Signaling Pathway in Retinal Ganglion Cells


Journal Title:

Journal of Neuroscience


Volume 33, Number 38


, Pages 14989-14997

Type of Work:

Article | Final Publisher PDF


Spatial variation in light intensity, called spatial contrast, comprises much of the visual information perceived by mammals, and the relative ability to detect contrast is referred to as contrast sensitivity (Purves et al., 2012). Recently, retinal dopamine D4 receptors (D4Rs) have been implicated in modulating contrast sensitivity (Jackson et al., 2012); however, the cellular and molecular mechanisms have not been elucidated. Our study demonstrates a circadian rhythm of contrast sensitivity that peaks during the daytime, and that its regulation involves interactions of D4Rs, the clock gene Npas2, and the clock-controlled gene adenylyl cyclase 1 (Adcy1) in a subset of retinal ganglion cells (RGCs). Targeted disruption of the gene encoding D4Rs reduces the amplitude of the contrast sensitivity rhythm by reducing daytime sensitivity and abolishes the rhythmic expression of Npas2 and Adcy1 mRNA in the ganglion cell layer (GCL) of the retina. Npas2−/− and Adcy1−/− mice show strikingly similar reductions in the contrast sensitivity rhythm to that in mice lacking D4Rs. Moreover, Adcy1 transcript rhythms were abolished in the GCL of Npas2−/− mice. Luciferase reporter assays demonstrated that the Adcy1 promoter is selectively activated by neuronal PAS-domain protein 2 (NPAS2)/BMAL1. Our results indicate that the contrast sensitivity rhythm is modulated by D4Rs via a signaling pathway that involves NPAS2-mediated circadian regulation of Adcy1. Hence, we have identified a circadian clock mechanism in a subset of RGCs that modulates an important aspect of retinal physiology and visual processing.

Copyright information:

© 2013 the authors 0270-6474/13/3314989-09$15.00/0

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