Abstract
Purpose :
Amacrine cells are a diverse class of retinal interneurons that interact with bipolar and ganglion cells to mediate complex visual computation in the inner plexiform layer. Interactions among amacrine cell types, however, are poorly understood except in a few special cases. Here, we report the synaptic interactions between the small-field, diffusely ramifying vGluT3 amacrine cell and wide-field, narrowly stratifying amacrine cells in the mouse retina.
Methods :
Patch-clamp recordings were made from wide-field amacrine cells in a flat-mount retinal preparation of vGluT3-Cre/ChR2-YFP mouse. vGluT3 amacrine cells were optogenetically activated by blue LED light, while potential postsynaptic amacrine cells were recorded under on-cell loose-patch and whole-cell voltage- or current-clamp, followed by receptive field characterization using patterned visual stimulation and morphological identification under two-photon imaging.
Results :
A small number of wide-field amacrine cells were selectively connected to vGluT3 amacrine cells via glycinergic synapses, showing direct postsynaptic current responses ranging in amplitude from 30 to 300 pA at 0 mV. These currents persisted in the presence of blockers of glutamate and GABA receptors, as well as gap junctions, but they were completely blocked by strychnine. The cells that received glycinergic input from vGluT3 cells did not display any detectable current response at -70 mV. The receptive field properties and the morphology of these cells, particularly a type of polyaxonal amacrine cell, were characterized. A characteristic form of local inhibition from vGluT amacrine cell to wide-field amacrine cells was identified.
Conclusions :
The study identified a specific form of vGluT3 cell-mediated glycinergic local suppression of wide-field inhibition in the inner retina
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.