September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Rod photoreceptors mediate light-evoked activity of dopaminergic amacrine cells across a wide range of light intensities
Author Affiliations & Notes
  • Xiwu Zhao
    Eye Research Institute, Oakland University, Rochester, Michigan, United States
    Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States
  • Sheng-Nan Qiao
    Eye Research Institute, Oakland University, Rochester, Michigan, United States
    Institute of Neurobiology, Fudan University, Shanghai, China
  • Yong-Mei Zhong
    Institute of Neurobiology, Fudan University, Shanghai, China
  • Kwoon Y Wong
    Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States
  • Dao-Qi Zhang
    Eye Research Institute, Oakland University, Rochester, Michigan, United States
  • Footnotes
    Commercial Relationships   Xiwu Zhao, None; Sheng-Nan Qiao, None; Yong-Mei Zhong, None; Kwoon Wong, None; Dao-Qi Zhang, None
  • Footnotes
    Support  NIH R01 EY022640
Investigative Ophthalmology & Visual Science September 2016, Vol.57, No Pagination Specified. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Xiwu Zhao, Sheng-Nan Qiao, Yong-Mei Zhong, Kwoon Y Wong, Dao-Qi Zhang; Rod photoreceptors mediate light-evoked activity of dopaminergic amacrine cells across a wide range of light intensities. Invest. Ophthalmol. Vis. Sci. 201657(12):.

      Download citation file:


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

      ×
  • Supplements
Abstract

Purpose : Dopamine plays a critical role in the retinal dark-light switch during the night-day transition. Yet, the way in which dopamine release is regulated in scotopic and mesopic lighting conditions remains unknown. Here we examine rod-mediated responses of dopaminergic amacrine cells (DACs) at a wide range of light intensities in order to understand the contribution of rods to the regulation of DAC activity.

Methods : A transgenic mouse model in which DACs are genetically labeled with red fluorescent protein was used. The cone phototransduction pathway was genetically eliminated in this model. Possible inputs from intrinsically photosensitive retinal ganglion cells to DACs were blocked by TTX (Prigge and Zhang, 2015). In most experiments, fluorescent labeling was visualized using a multi-photon laser to minimize photopigment bleaching.

Results : At a holding potential of -70 mV, DACs exhibited inward currents at light onset (white light, 1-s duration) with a threshold light intensity of 7.5 log quanta cm-2 s-1 (near the rod sensitivity threshold). The peak amplitude of these light-evoked currents gradually increased as the light intensity increased and reached its maximum value (55.8±25.6 pA, n=3) at 9.5 log quanta cm-2 s-1. As light intensity exceeded 9.5 log quanta cm-2 s-1, peak response amplitude remained unchanged although the responses became more prolonged. The responses lasted for ~15 s (n=3) after light off at 13.5 log quanta cm-2 s-1. In addition, rod-mediated responses of DACs were persistent during 120-s steady background illumination at both lower (8.5 log quanta cm-2 s-1, n=3) and higher (11.5 log quanta cm-2 s-1, n=3) intensities. DACs also responded to flashing lights (8.5 log quanta cm-2 s-1 at 1 Hz and 11.5 log quanta cm-2 s-1 at 0.25 Hz, n=3). Furthermore, DACs exhibited a transient outward current at light onset when the holding potential was at 0 mV. Strychnine (a glycine receptor antagonist) increased the light-evoked inward current recorded at -70 mV but attenuated the outward current measured at 0 mV, suggesting that rod-mediated responses of DACs consist of both excitatory and inhibitory components.

Conclusions : Our results suggest that rods can mediate light-evoked activity of DACs at a wide range of light intensities, thus potentially triggering dopamine release in scotopic, mesopic or even photopic lighting conditions.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×