Journal Article

Genetic targeting and physiological features of VGLUT3+ amacrine cells

DIAMOND, JEFFREY S., GRIMES, WILLIAM N., EDWARDS, ROBERT H., OESCH, NICHOLAS, SEAL, REBECCA P.

2011

Overview

Amacrine cells constitute a diverse class of interneurons that contribute to visual signal processing in the inner retina, but surprisingly, little is known about the physiology of most amacrine cell subtypes. Here, we have taken advantage of the sparse expression of vesicular glutamate transporter 3 (VGLUT3) in the mammalian retina to target the expression of yellow fluorescent protein (YFP) to a unique population of amacrine cells using a new transgenic mouse line. Electrophysiological recordings made from YFP-positive (VGLUT3+) amacrine cells provide the first functional data regarding the active membrane properties and synaptic connections of this recently identified cell type. We found that VGLUT3+ amacrine cells receive direct synaptic input from bipolar cells via both N-methyl-d-aspartate receptors (NMDARs) and non-NMDARs. Voltage-gated sodium channels amplified these excitatory inputs but repetitive spiking was never observed. VGLUT3+ amacrine cells responded transiently to both light increments (ON response) and decrements (OFF response); ON responses consisted exclusively of inhibitory inputs, while OFF responses comprised both excitatory and inhibitory components, although the inhibitory conductance was larger in amplitude and longer in time course. The physiological properties and anatomical features of the VGLUT3+ amacrine cells suggest that this bistratified interneuron may play a role in disinhibitory signaling and/or crossover inhibition between parallel pathways in the retina.

• Publisher: Cambridge University Press
• Subject: Amacrine cells / Amacrine Cells - classification / Amacrine Cells - drug effects / Amacrine Cells - physiology / Amino Acid Transport Systems, Acidic - genetics / Amino Acid Transport Systems, Acidic - metabolism / Animals / Animals, Newborn / Biological and medical sciences / Biophysics / Bipolar cells / Cadmium Chloride - pharmacology / Data processing / Electrophysiological recording / Excitatory Amino Acid Antagonists - pharmacology / Excitatory Postsynaptic Potentials - drug effects / Excitatory Postsynaptic Potentials - genetics / Eye and associated structures. Visual pathways and centers. Vision / Firing pattern / Fundamental and applied biological sciences. Psychology / Glutamic acid receptors / Glutamic acid transporter / Green Fluorescent Proteins - genetics / In Vitro Techniques / Interneurons / Light / Light effects / Membrane Potentials - drug effects / Membrane Potentials - genetics / Mice / Mice, Transgenic / N-Methyl-D-aspartic acid receptors / Nervous system / Peptides - pharmacology / Retina / Retina - cytology / Retinal Bipolar Cells - drug effects / Retinal Bipolar Cells - physiology / Signal transduction / Sodium Channel Blockers - pharmacology / Sodium channels (voltage-gated) / Synapses / Synapses - genetics / Synapses - physiology / Tetrodotoxin - pharmacology / Transgenic mice / Vertebrates: nervous system and sense organs / Whole Blood Coagulation Time / yellow fluorescent protein