PUBLICATION
Electrophysiological evidence of GABAA and GABAC receptors on zebrafish retinal bipolar cells
- Authors
- Connaughton, V.P., Nelson, R., and Bender, A.M.
- ID
- ZDB-PUB-080501-3
- Date
- 2008
- Source
- Visual neuroscience 25(2): 139-153 (Journal)
- Registered Authors
- Connaughton, Victoria P.
- Keywords
- Retina, Bipolar cells, GABA, Zebrafish, Inhibition
- MeSH Terms
-
- Animals
- Bicuculline/pharmacology
- Dendrites/metabolism
- Electrophysiology
- GABA Antagonists/pharmacology
- In Vitro Techniques
- Patch-Clamp Techniques
- Picrotoxin/pharmacology
- Presynaptic Terminals/metabolism
- Receptors, GABA/drug effects
- Receptors, GABA/metabolism*
- Receptors, GABA-A/drug effects
- Receptors, GABA-A/metabolism*
- Retina/drug effects
- Retina/metabolism
- Retina/physiology
- Retinal Bipolar Cells/metabolism*
- Retinal Bipolar Cells/physiology
- Zebrafish/metabolism*
- Zinc/pharmacology
- gamma-Aminobutyric Acid/pharmacology
- PubMed
- 18442437 Full text @ Vis. Neurosci.
Citation
Connaughton, V.P., Nelson, R., and Bender, A.M. (2008) Electrophysiological evidence of GABAA and GABAC receptors on zebrafish retinal bipolar cells. Visual neuroscience. 25(2):139-153.
Abstract
To refine inhibitory circuitry models for ON and OFF pathways in zebrafish retina, GABAergic properties of zebrafish bipolar cells were studied with two techniques: whole cell patch responses to GABA puffs in retinal slice, and voltage probe responses in isolated cells. Retinal slices documented predominantly axon terminal responses; isolated cells revealed mainly soma-dendritic responses. In the slice, GABA elicited a conductance increase, GABA responses were more robust at axon terminals than dendrites, and Erev varied with [Cl(-)]in. Axon terminals of ON- and OFF-type cells were similarly sensitive to GABA (30-40 pA peak current); axotomized cells were unresponsive. Bicuculline-sensitive, picrotoxin-sensitive, and picrotoxin-insensitive components were identified. Muscimol was as effective as GABA; baclofen was ineffective. Isolated bipolar cells were either intact or axotomized. Even in cells without an axon, GABA or muscimol (but not baclofen) hyperpolarized dendritic and somatic regions, suggesting significant distal expression. Median fluorescence change for GABA was -0.22 log units (approximately -16 mV); median half-amplitude dose was 0.4 microM. Reduced [Cl(-)]out blocked GABA responses. GABA hyperpolarized isolated ON-bipolar cells; OFF-cells were either unresponsive or depolarized. Hyperpolarizing GABA responses in isolated cells were bicuculline and TPMPA insensitive, but blocked or partially blocked by picrotoxin or zinc. In summary, axon terminals contain bicuculline-sensitive GABAA receptors and both picrotoxin-sensitive and insensitive GABAC receptors. Dendritic processes express zinc- and picrotoxin-sensitive GABAC receptors.
Genes / Markers
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping