Visual Neuroscience

Glycine- and GABA-activated inhibitory currents on axon terminals of rabbit cone bipolar cells

CHENGWEN  ZHOU  a1 c2 and RAMON F.  DACHEUX  a1 c1
a1 Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama

Article author query
zhou c   [Google Scholar] 
dacheux rf   [Google Scholar] 


Glycine- and GABA-activated currents were examined in the axon terminals of 12 types of rabbit cone bipolar cells. In the superfused retinal slice, a cell was voltage clamped at 0 mV in the presence of cobalt; then glycine or GABA was puffed onto the axon terminal. Types CBa1, CBa2, and a few CBa1-2 cells demonstrated larger glycine-activated currents than GABA-activated ones. However, some OFF cells (CBa2n, CBa1-2n, CBa1w), most CBa1-2, and most ON cells (CBb3, CBb3-4, CBb3n, and CBb4) displayed larger GABA-activated currents. The ON cell, CBb5, possessed only a GABA-activated current. The predominance of glycinergic currents in CBa1, CBa2, and a few CBa1-2 cells suggests a major input from the glycinergic AII amacrine cell and thus a key role for these cells in the rod bipolar pathway. Certain OFF cells (most CBa1-2) expressed larger GABA-activated currents. All types expressed both GABAA and GABAC currents about equally, although most OFF types (CBa1, CB a2n, CBa1-2, and CBa2n) displayed a slightly greater GABAA component.

(Received March 24 2005)
(Accepted May 24 2005)

Key Words: Glycine-activated current; GABA-activated current; ON and OFF cone bipolar cell; Axon terminals.

c1 Address correspondence and reprint requests to: Ramon F. Dacheux, Department of Ophthalmology, University of Alabama at Birmingham, Callahan Eye Foundation Hospital, 700 18th Street South, Birmingham, AL 35294-0009, USA. E-mail:
c2 E-mail: