Melanopsin phototransduction contributes to light-evoked choroidal expansion and rod L-type calcium channel function in vivo

Bruce A. Berkowitz*, Tiffany Schmidt, Robert H. Podolsky, Robin Roberts

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


PURPOSE. In humans, rodents, and pigeons, the dark → light transition signals nonretinal brain tissue to increase choroidal thickness, a major control element of choroidal blood flow, and thus of photoreceptor and retinal pigment epithelium function. However, it is unclear which photopigments in the retina relay the light signal to the brain. Here, we test the hypothesis that melanopsin (Opn4)-regulated phototransduction modulates light-evoked choroidal thickness expansion in mice. METHODS. Two-month-old C57Bl/6 wild-type (B6), 4- to 5-month-old C57Bl/6/129S6 wild-type (B6 + S6), and 2-month-old melanopsin knockout (Opn4-/-) on a B6 + S6 background were studied. Retinal anatomy was evaluated in vivo by optical coherence tomography and MRI. Choroidal thickness in dark and light were measured by diffusion-weighted MRI. Rod cell Ltype calcium channel (LTCC) function in dark and light (manganese-enhanced MRI [MEMRI]) was also measured. RESULTS. Opn4-/- mice did not show the light-evoked expansion of choroidal thickness observed in B6 and B6 + S6 controls. Additionally, Opn4-/- mice had lower than normal rod cell and inner retinal LTCC function in the dark but not in the light. These deficits were not due to structural abnormalities because retinal laminar architecture and thickness, and choroidal thickness in the Opn4-/- mice were similar to controls. CONCLUSIONS. First time evidence is provided that melanopsin phototransduction contributes to dark → light control of murine choroidal thickness. The data also highlight a contribution in vivo of melanopsin phototransduction to rod cell and inner retinal depolarization in the dark.

Original languageEnglish (US)
Pages (from-to)5314-5319
Number of pages6
JournalInvestigative Ophthalmology and Visual Science
Issue number13
StatePublished - Oct 2016


  • Choroidal thickness
  • Diffusion
  • L-type calcium channels
  • MRI
  • Retina
  • Rod cells

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience


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