March 2012
Volume 53, Issue 14
Free
ARVO Annual Meeting Abstract  |   March 2012
Light/Dark Adaptive Regulation of GABAA Receptor and NKCC Expression and Activity Modulates Direct, GABA-mediated Horizontal Cell Signaling to ON-Cone Bipolar Cells
Author Affiliations & Notes
  • Antoine J. Chaffiol
    Neuroscience, Ohio State Univ College of Med, Columbus, Ohio
  • Yu Cao
    Neuroscience, Ohio State Univ College of Med, Columbus, Ohio
  • Masaaki Ishii
    Neuroscience, Ohio State Univ College of Med, Columbus, Ohio
  • Christophe Ribelayga
    Neuroscience, Ohio State Univ College of Med, Columbus, Ohio
  • Stuart C. Mangel
    Neuroscience, Ohio State Univ College of Med, Columbus, Ohio
  • Footnotes
    Commercial Relationships  Antoine J. Chaffiol, None; Yu Cao, None; Masaaki Ishii, None; Christophe Ribelayga, None; Stuart C. Mangel, None
  • Footnotes
    Support  NEI grants EY014235 and EY005102 to S.C.M.
Investigative Ophthalmology & Visual Science March 2012, Vol.53, 4306. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Antoine J. Chaffiol, Yu Cao, Masaaki Ishii, Christophe Ribelayga, Stuart C. Mangel; Light/Dark Adaptive Regulation of GABAA Receptor and NKCC Expression and Activity Modulates Direct, GABA-mediated Horizontal Cell Signaling to ON-Cone Bipolar Cells. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4306.

      Download citation file:


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

      ×
  • Supplements
Abstract

Purpose: : Ganglion cells (GCs) display a center-surround receptive field (RF) following prolonged (>30 min) light adaptation, but exhibit minimal surrounds following prolonged dark adaptation (Barlow et al., 1957). Bipolar cell (BC) surround strength also decreases when the background illumination is reduced (Fahey & Burkhardt, 2003). Under light-adapted conditions, horizontal cells (HCs) contribute to ON-GC surrounds (Mangel, 1991) possibly by releasing GABA (Guo et al., 2010) directly onto ON-cone BC (cBC) dendrites, which express Cl-permeable GABAA receptor (GABAAR) channels and the Cl cotransporter NKCC. We thus tested whether light/dark adaptive regulation of GABAARs and NKCC modulates direct, GABA-mediated HC signaling to ON-cBC surrounds.

Methods: : Rabbits were bright light (photopic)- or dark (low scotopic)-adapted for 1 h or rabbit retinas were incubated in Ringer for 1 h under light-adapted conditions with or without test drugs. Retinal sections were processed in an identical manner for immunostaining with antibodies against the β2/3 subunit-containing GABAAR (bd-17) and NKCC (T4). The effects of current injections into HCs on the activity of nearby ON-GCs in rabbit eyecups and application of dopamine, APB (mGluR6 agonist that blocks cone to ON-BC signaling), and gabazine (GABAAR antagonist) on cBCs in rabbit retinal slices were studied.

Results: : Intense GABAAR and NKCC antibody labeling were observed in ON-BC dendrites under light-adapted control conditions, but both immunosignals were minimal in dark-adapted retinas or in light-adapted retinas pre-treated with the dopamine D1R antagonist SCH23390. Under light-adapted conditions, picrotoxin (GABAA/C antagonist) and bumetanide (NKCC inhibitor) blocked the effect of HC polarizations on ON-GC spike activity. Picrotoxin also eliminated the reduction in the ON-GC center response produced by hyperpolarizing HCs. Dopamine application and prolonged light adaptation decreased the RF center size and strengthened the RF surround of ON-cBCs. Following APB application in the presence of dopamine, ON-cBCs produced opposite polarity (i.e., hyperpolarizing) surround responses that were blocked by gabazine.

Conclusions: : These results suggest that prolonged light adaptation increases D1R activation so that GABAAR and NKCC expression and activity of ON-cBC dendrites are enhanced, producing the RF surrounds of ON-cBCs and ON-GCs via direct GABA-mediated HC excitation of ON-cBC dendrites. Conversely, the decrease in D1R activation following prolonged darkness substantially reduces GABAAR and NKCC expression and activity, weakening ON-cBC and ON-GC surrounds.

Keywords: receptive fields • inhibitory receptors • ion transporters 
×
×

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.

×