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Upregulation of high-affinity GABA(A) receptors in cultured rat dorsal root ganglion neurons.
Upregulation of high-affinity GABA(A) receptors in cultured rat dorsal root ganglion neurons.
- Source :
-
Neuroscience [Neuroscience] 2012 Apr 19; Vol. 208, pp. 133-42. Date of Electronic Publication: 2012 Feb 08. - Publication Year :
- 2012
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Abstract
- Despite evidence that high-affinity GABA(A) receptor subunit mRNA and protein are present in dorsal root ganglia (DRG), low-affinity currents dominate those detected in acutely dissociated DRG neurons in vitro. This observation raises the possibility that high-affinity receptors are normally trafficked out of the DRG toward central and peripheral terminals. We therefore hypothesized that with time in culture, there would be an increase in high-affinity GABA(A) currents in DRG neurons. To test this hypothesis, we studied dissociated DRG neurons 2 h (acute) and 24 h (cultured) after plating with whole-cell patch-clamp techniques, Western blot, and semiquantitative reverse transcriptase polymerase chain reaction (sqRT-PCR) analysis. GABA(A) current density increases dramatically with time in culture in association with the emergence of two persistent currents with EC50's of 0.25±0.01 μM and 3.2±0.02 μM for GABA activation. In a subpopulation of neurons, there was also an increase in the potency of GABA activation of the transient current from an EC50 of 78.16±10.1 μM to 9.56±1.3 μM with time in culture. A fraction of the high-affinity current was potentiated by δ-subunit agonist 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridine-3-ol (THIP). δ-subunit immunoreactivity was largely restricted to the cytosolic fraction in acute, but the membrane fraction in cultured, DRG neurons, with no detectable change in δ-subunit mRNA. However, the emergence of a high-affinity current blocked by THIP and insensitive to bicuculline was detected in a subpopulation of cultured neurons as well in association with an increase in ρ2- and ρ3-subunit mRNA in cultured DRG neurons. Our results suggest that high-affinity δ-subunit-containing GABA(A) receptors are normally trafficked out of the DRG where they are targeted to peripheral and central processes. They also highlight that the interpretation of data obtained from cultured DRG neurons should be made with caution.<br /> (Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.)
- Subjects :
- Animals
Bicuculline pharmacology
Blotting, Western
Cells, Cultured
Crotonates pharmacology
Electrophysiological Phenomena
GABA Agonists pharmacology
GABA Antagonists pharmacology
Ganglia, Spinal cytology
Ganglia, Spinal drug effects
Isoxazoles pharmacology
Male
Patch-Clamp Techniques
Rats
Rats, Sprague-Dawley
Real-Time Polymerase Chain Reaction
Time Factors
Up-Regulation drug effects
Up-Regulation physiology
Ganglia, Spinal metabolism
Neurons metabolism
Receptors, GABA-A biosynthesis
Subjects
Details
- Language :
- English
- ISSN :
- 1873-7544
- Volume :
- 208
- Database :
- MEDLINE
- Journal :
- Neuroscience
- Publication Type :
- Academic Journal
- Accession number :
- 22366297
- Full Text :
- https://doi.org/10.1016/j.neuroscience.2012.01.050