April 2011
Volume 52, Issue 14
ARVO Annual Meeting Abstract  |   April 2011
S-opsin Stimulation in Dually Expressing Cone Photoreceptors of Mice Suppresses ERG Responses to M Cone Pigment Stimuli
Author Affiliations & Notes
  • Scott H. Greenwald
    Ophthalmology, University of Washington, Seattle, Washington
  • James A. Kuchenbecker
    Ophthalmology, University of Washington, Seattle, Washington
  • Dan K. Roberson
    Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin
  • Maureen Neitz
    Ophthalmology, University of Washington, Seattle, Washington
  • Jay Neitz
    Ophthalmology, University of Washington, Seattle, Washington
  • Footnotes
    Commercial Relationships  Scott H. Greenwald, None; James A. Kuchenbecker, None; Dan K. Roberson, None; Maureen Neitz, None; Jay Neitz, None
  • Footnotes
    Support  Research to Prevent Blindness, NIH grants P30EY01730, R01EY09620, T32EY007031
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 3909. doi:
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      Scott H. Greenwald, James A. Kuchenbecker, Dan K. Roberson, Maureen Neitz, Jay Neitz; S-opsin Stimulation in Dually Expressing Cone Photoreceptors of Mice Suppresses ERG Responses to M Cone Pigment Stimuli. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3909.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: : Adult human cone photoreceptors express only a single class of opsin, but many murine cones express both S- and M-opsin. This feature of mouse cones, together with the ability to genetically manipulate them, affords opportunities to answer basic questions about the mechanisms responsible for cone opsin expression and function.

Methods: : Targeted gene replacement technology was used to delete exons 1 through 4 of the mouse Opn1sw gene on chromosome 6. Full field, photopic 1 Hz ON-OFF, cone isolating ERGs were performed on anesthetized, six-month-old wildtype mice (n=9) and age-matched Opn1sw(-/-) mice (n=10), as well as on two adult human subjects. A 520 nm light isolated M cone responses. To isolate S/UV cones a 365 nm light (414 nm for human) was alternated with a 520 nm light (50% duty cycle) in a silent substitution paradigm.

Results: : In wildtype mice, the ERG b-wave generated in response to an M-isolating light was suppressed by 40% (p=0.0005) after exposure to an S cone stimulus; however, this was not observed in knockout mice (-5.2%; p=0.57) or in humans (-5.8%; p = 0.35). The time course of recovery after a 20 sec exposure to light that stimulated UV/S cones was 10-15 minutes. When the S cone stimulation was increased in duration, the M response was further suppressed and the recovery time was greatly extended. Pre-exposing a wildtype mouse to 520 nm light in the absence of the S cone stimulation did not result in a decreased M cone ERG. Interestingly, in the absence of S-opsin stimulating pre-exposure, the trend of wildtype mice was toward having larger b-wave responses to 520 nm lights as compared to knockout mice (233µV ± 13 vs 193µV ± 13; p=0.06). This result is the opposite of what would have been expected if, in the knockout, additional M-opsin replaced S-opsin in cones that would have co-expressed the two opsins in the wildtype. Anatomical results confirm that M-opsin did not replace S-opsin in Opn1sw(-/-) mice.

Conclusions: : S-opsin activation suppresses ERG responses to middle wavelength light absorbed exclusively by M pigment when S- and M-opsins are dually expressed within single cones.

Keywords: photoreceptors • color pigments and opsins • electroretinography: non-clinical 

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