Light-evoked currents in retinal ganglion cells from dystrophic RCS rats.
OBJECTIVE
To study the electrophysiological properties of the light-evoked currents in ganglion cells in situations of retinal degeneration.


METHODS
We investigated light-evoked currents in ganglion cells by performing whole-cell patch-clamp recordings from ganglion cells using a retina-stretched preparation from Royal College of Surgeons (RCS) rats, a model of retinal degeneration and congenic controls at different ages. Pharmacological inhibitors of the AMPA receptor (NBQX), GABA receptor (BMI), and sodium channels (TTX) were used to identify the components of the light-evoked currents in ON, OFF and ON-OFF retinal ganglion cells.


RESULTS
We found that the light-evoked currents in ganglion cells from control rats were inhibited by NBQX, BMI and TTX, suggesting that AMPA receptors, GABA receptors and sodium channels contribute to these currents in ganglion cells. However, only AMPA receptor-mediated currents were recorded in RCS rats. Light-evoked inward currents were absent in the majority of ganglion cells from RCS rats, particularly at the later stages of retinal degeneration. At earlier stages of retinal degeneration, we found that both the timing and amplitude of light-evoked currents are significantly different in ganglion cells from RCS and control rats.


CONCLUSIONS
Our study furthers the understanding of the electrophysiological characteristics of retinal ganglion cells during retinal degeneration, and provides insight into the optimal timing for the treatment of retinal degeneration.
Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, PR China.
Kang
K
Liu
Yi
Y
Wang
Zhengqin
Z
Yin
Chuanhuang
C
Weng
D000704:Analysis of Variance; D000818:Animals; D004195:Disease Models, Animal; D005074:Evoked Potentials, Visual / Q000187:drug effects / Q000502:physiology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D051381:Rats; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors / Q000502:physiology; D018079:Receptors, GABA / Q000502:physiology; D058499:Retinal Dystrophies / Q000503:physiopathology*; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000502:physiology*; D015222:Sodium Channels / Q000502:physiology
D018691:Excitatory Amino Acid Antagonists; D018091:Receptors, AMPA; D018079:Receptors, GABA; D015222:Sodium Channels