Dopamine mediates circadian rhythms of rod-cone dominance in the Japanese quail retina

• Type of Material: Article
• Authors: Mary K. Manglapus, State University of New York Syracuse; P Michael Iuvone, Emory University; Herbert Underwood, North Carolina State University; Mary E. Pierce, State University of New York Syracuse; Robert B. Barlow, State University of New York Syracuse
• Language: English
• Date: 1999-05-15
• Publisher: Lippincott, Williams & Wilkins
• Publication Version: Final Published Version
• Copyright Statement: © 1999 Society for Neuroscience
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1523/JNEUROSCI.19-10-04132.1999
• Title of Journal or Parent Work: Journal of Neuroscience Nursing
• ISSN: 0888-0395
• Volume: 19
• Issue: 10
• Start Page: 4132
• End Page: 4141
• Grant/Funding Information: This research was supported in part by Research to Prevent Blindness, National Institutes of Health (NIH) Grant EY 00667 and National Science Foundation Grant IBN 9696208 to R.B.B., NIH Grant EY 04864 to P.M.I., NIH Grant EY 10672 to M.E.P., and NIH Grant NS 20961 to H.U.
• Keywords: CHICKEN RETINA; rod-cone dominance; MAMMALIAN RETINA; dopamine; ERG; Science & Technology; SEROTONIN N-ACETYLTRANSFERASE; XENOPUS-LAEVIS; BIOLOGICAL CLOCK; retina; TRYPTOPHAN-HYDROXYLASE ACTIVITY; quail; VISUAL SENSITIVITY; HORIZONTAL CELLS; RETINOMOTOR MOVEMENTS; Neurosciences & Neurology; Neurosciences; Life Sciences & Biomedicine; circadian rhythm; OCULAR MELATONIN
• Research Categories: Biology, Zoology; Health Sciences, Opthamology; Health Sciences, Pharmacology

Abstract

A circadian clock modulates the functional organization of the Japanese quail retina. Under conditions of constant darkness, rods dominate electroretinogram (ERG) b-wave responses at night, and cones dominate them during the day, yielding a circadian rhythm in retinal sensitivity and rod- cone dominance. The activity of tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis, also exhibits a circadian rhythm in the retina with approximately threefold higher levels during the day than at night. The rhythm of tyrosine hydroxylase activity is opposite in phase to the circadian activity of tryptophan hydroxylase, the first enzyme in the melatonin biosynthetic pathway. We tested whether dopamine may be related to the physiological rhythms of the retina by examining the actions of pharmacological agents that effect dopamine receptors. We found that blocking dopamine D2 receptors in the retina during the day mimics the nighttime state by increasing the amplitude of the b-wave and shifting the retina to rod dominance. Conversely, activating D2 receptors at night mimics the daytime state by decreasing the amplitude of the b-wave and shifting the retina to cone dominance. A selective antagonist for D1 dopamine receptors has no effect on retinal sensitivity or rod-cone dominance. Reducing retinal dopamine partially abolishes rhythms in sensitivity and yields a rod- dominated retina regardless of the time of day. These results suggest that dopamine, under the control of a circadian oscillator, has a key rote in modulating sensitivity and rod-cone dominance in the Japanese quail retina.