Kv3 channels contribute to the delayed rectifier current in small cultured mouse dorsal root ganglion neurons

2012 ◽  
Vol 303 (4) ◽  
pp. C406-C415 ◽  
Author(s):  
Elke Bocksteins ◽  
Gerda Van de Vijver ◽  
Pierre-Paul Van Bogaert ◽  
Dirk J. Snyders
Keyword(s):  
Dorsal Root Ganglion ◽  
Dorsal Root ◽  
Neuronal Excitability ◽  
Dorsal Root Ganglion Neurons ◽  
Delayed Rectifier ◽  
Drg Neurons ◽  
M Current ◽  
Delayed Rectifier Current ◽  
Mouse Dorsal Root Ganglion ◽  
Ganglion Neurons

Delayed rectifier voltage-gated K+ (KV) channels are important determinants of neuronal excitability. However, the large number of KV subunits poses a major challenge to establish the molecular composition of the native neuronal K+ currents. A large part (∼60%) of the delayed rectifier current ( IK) in small mouse dorsal root ganglion (DRG) neurons has been shown to be carried by both homotetrameric KV2.1 and heterotetrameric channels of KV2 subunits with silent KV subunits (KVS), while a contribution of KV1 channels has also been demonstrated. Because KV3 subunits also generate delayed rectifier currents, we investigated the contribution of KV3 subunits to IK in small mouse DRG neurons. After stromatoxin (ScTx) pretreatment to block the KV2-containing component, application of 1 mM TEA caused significant additional block, indicating that the ScTx-insensitive part of IK could include KV1, KV3, and/or M-current channels (KCNQ2/3). Combining ScTx and dendrotoxin confirmed a relevant contribution of KV2 and KV2/KVS, and KV1 subunits to IK in small mouse DRG neurons. After application of these toxins, a significant TEA-sensitive current (∼19% of total IK) remained with biophysical properties that corresponded to those of KV3 currents obtained in expression systems. Using RT-PCR, we detected KV3.1–3 mRNA in DRG neurons. Furthermore, Western blot and immunocytochemistry using KV3.1-specific antibodies confirmed the presence of KV3.1 in cultured DRG neurons. These biophysical, pharmacological, and molecular results demonstrate a relevant contribution (∼19%) of KV3-containing channels to IK in small mouse DRG neurons, supporting a substantial role for KV3 subunits in these neurons.

scholarly journals Chronic compression of mouse dorsal root ganglion alters voltage-gated sodium and potassium currents in medium-sized dorsal root ganglion neurons

2011 ◽  
Vol 106 (6) ◽  
pp. 3067-3072 ◽  
Author(s):  
Ni Fan ◽  
David F. Donnelly ◽  
Robert H. LaMotte
Keyword(s):  
Dorsal Root Ganglion ◽  
Dorsal Root ◽  
Small Diameter ◽  
Radicular Pain ◽  
Dorsal Root Ganglion Neurons ◽  
Delayed Rectifier ◽  
Drg Neurons ◽  
Voltage Dependent ◽  
Ganglion Neurons

Chronic compression (CCD) of the dorsal root ganglion (DRG) is a model of human radicular pain produced by intraforaminal stenosis and other disorders affecting the DRG, spinal nerve, or root. Previously, we examined electrophysiological changes in small-diameter lumbar level 3 (L3) and L4 DRG neurons treated with CCD; the present study extends these observations to medium-sized DRG neurons, which mediate additional sensory modalities, both nociceptive and non-nociceptive. Whole-cell patch-clamp recordings were obtained from medium-sized somata in the intact DRG in vitro. Compared with neurons from unoperated control animals, CCD neurons exhibited a decrease in the current threshold for action potential generation. In the CCD group, current densities of TTX-resistant and TTX-sensitive Na+ current were increased, whereas the density of delayed rectifier voltage-dependent K+ current was decreased. No change was observed in the transient or “A” current after CCD. We conclude that CCD in the mouse produces hyperexcitability in medium-sized DRG neurons, and the hyperexcitability is associated with an increased density of Na+ current and a decreased density of delayed rectifier voltage-dependent K+ current.

Reduction in Potassium Currents in Identified Cutaneous Afferent Dorsal Root Ganglion Neurons After Axotomy

1999 ◽  
Vol 82 (2) ◽  
pp. 700-708 ◽  
Author(s):  
Brian Everill ◽  
Jeffery D. Kocsis
Keyword(s):  
Dorsal Root Ganglion ◽  
Dorsal Root ◽  
Neuronal Excitability ◽  
Potassium Currents ◽  
Dorsal Root Ganglion Neurons ◽  
Channel Blockers ◽  
Afferent Neurons ◽  
Drg Neurons ◽  
Whole Cell Patch Clamp ◽  
Ganglion Neurons

Potassium currents have an important role in modulating neuronal excitability. We have investigated the effects of axotomy on three voltage-activated K+ currents, one sustained and two transient, in cutaneous afferent dorsal root ganglion (DRG) neurons. Fourteen to 21 days after axotomy, L4 and L5 DRG neurons were acutely dissociated and were studied 2–8 h after plating. Whole cell patch-clamp recordings were obtained from identified cutaneous afferent neurons (46–50 μm diam); K+ currents were isolated by blocking Na+ and Ca2+ currents with appropriate ion replacement and channel blockers. Separation of the current components was achieved on the basis of sensitivity to dendrotoxin or 4-aminopyridine and by the response to variation in conditioning voltage. Both control and injured neurons displayed qualitatively similar complex K+ currents composed of distinct kinetic and pharmacological components. Three distinct K+ current components, a sustained ( I K) and two transient ( I A and I D), were identified in variable proportions. However, total peak current was reduced by 52% in the axotomized cells when compared with control cells. Two current components were reduced after ligation, I Aby 60%, I K by over 65%, compared with control cells. I D appeared unaffected after acute ligation. These results indicate a large reduction in overall K+ current, resulting from reductions in I K and I A, on large cutaneous afferent neurons after nerve ligation and have implications for excitability changes of injured primary afferent neurons.

GDNF and NGF Reverse Changes in Repriming of TTX-Sensitive Na+ Currents Following Axotomy of Dorsal Root Ganglion Neurons

2002 ◽  
Vol 88 (2) ◽  
pp. 650-658 ◽  
Author(s):  
Andreas Leffler ◽  
Theodore R. Cummins ◽  
Sulayman D. Dib-Hajj ◽  
William N. Hormuzdiar ◽  
Joel A. Black ◽  
...  
Keyword(s):  
Dorsal Root Ganglion ◽  
Sodium Channel ◽  
Sensory Neurons ◽  
Dorsal Root ◽  
Neuronal Excitability ◽  
Dorsal Root Ganglion Neurons ◽  
Current Profile ◽  
Drg Neurons ◽  
Α Subunit ◽  
Ganglion Neurons

Uninjured C-type rat dorsal root ganglion (DRG) neurons predominantly express slowly inactivating TTX-resistant (TTX-R) and slowly repriming TTX-sensitive (TTX-S) Na+ currents. After peripheral axotomy, TTX-R current density is reduced and rapidly repriming TTX-S currents emerge and predominate. The change in TTX-S repriming kinetics is paralleled by an increase in the level of transcripts and protein for the Nav1.3 sodium channel α-subunit, which is known to exhibit rapid repriming. Changes in Na+current profile and kinetics in DRG neurons may substantially alter neuronal excitability and could contribute to some states of chronic pain associated with injury of sensory neurons. In the present study, we asked whether glial-derived neurotrophic factor (GDNF) and nerve growth factor (NGF), which have been shown to prevent some axotomy-induced changes such as the loss of TTX-R Na+ current expression in DRG neurons, can ameliorate the axotomy-induced change in TTX-S Na+ current repriming kinetics. We show that intrathecally administered GDNF and NGF, delivered individually, can partially reverse the effect of axotomy on the repriming kinetics of TTX-S Na+ currents. When GDNF and NGF were co-administered, the repriming kinetics were fully rescued. We observed parallel effects of GDNF and NGF on the Nav1.3 sodium channel transcript levels in axotomized DRG. Both GDNF and NGF were able to partially reverse the axotomy-induced increase in Nav1.3 mRNA, with GDNF plus NGF producing the largest effect. Our data indicate that both GDNF and NGF can partially reverse an important effect of axotomy on the electrogenic properties of sensory neurons and that their effect is additive.

scholarly journals On the inhibition of capsaicin response in dorsal root ganglion neurons by nobilamide B and analogues: a structure–activity relationship study

MedChemComm ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 1673-1678
Author(s):  
Oliver John V. Belleza ◽  
Jortan O. Tun ◽  
Gisela P. Concepcion ◽  
Aaron Joseph L. Villaraza
Keyword(s):  
Dorsal Root Ganglion ◽  
Primary Culture ◽  
Dorsal Root ◽  
Dorsal Root Ganglion Neurons ◽  
Activity Relationship ◽  
Drg Neurons ◽  
Structure Activity ◽  
Relationship Study ◽  
Trpv1 Antagonist ◽  
Ganglion Neurons

Nobilamide B, a TRPV1 antagonist, and a series of Ala-substituted analogues were synthesized and their neuroactivity was assessed in a primary culture of dorsal root ganglion (DRG) neurons.

Variation in IH, IIR, and ILEAK between acutely isolated adult rat dorsal root ganglion neurons of different size

1994 ◽  
Vol 71 (1) ◽  
pp. 271-279 ◽  
Author(s):  
R. S. Scroggs ◽  
S. M. Todorovic ◽  
E. G. Anderson ◽  
A. P. Fox
Keyword(s):  
Dorsal Root Ganglion ◽  
Action Potentials ◽  
Dorsal Root ◽  
Membrane Surface ◽  
Small Diameter ◽  
Reversal Potential ◽  
Dorsal Root Ganglion Neurons ◽  
Time Dependent ◽  
Drg Neurons ◽  
Ganglion Neurons

1. The distribution of IH, IIR, and ILEAK was studied in different diameter rat dorsal root ganglion (DRG) neuron cell bodies (neurons). DRG neurons were studied in three diameter ranges: small (19–27 microns), medium (33–37 microns), and large (44-54 microns). IH was defined as a slowly activating inward current evoked by hyperpolarizing voltage steps from a holding potential (HP) of -60 mV, and blocked by 1 mM Cs2+ but not 1 mM Ba2+. Inward rectifier current (IIR) was defined as a rapidly activating current evoked by hyperpolarizations from HP -60 mV, which rectified inwardly around the reversal potential for potassium (EK), and was completely blocked by 100 microM Ba2+. ILEAK was defined as an outward resting current at HP -60 mV, which did not rectify and was blocked by 100 microM Ba2+ but not by 2 mM Cs+. 2. IH was observed in 23 of 23 large, 11 of 12 medium, and in 9 of 20 small diameter DRG neurons tested. Peak IH normalized to membrane surface area was significantly greater in large than in medium or small diameter DRG neurons expressing IH. All neurons exhibiting IH under voltage clamp conditions had short duration action potentials and exhibited time-dependent rectification under current clamp conditions, properties similar to A-type DRG neurons. The 11 small diameter neurons not expressing IH had long duration action potentials and did not exhibit time-dependent rectification, properties similar to C-type DRG neurons. 3. IIR was detected in 18 of 22 medium diameter neurons tested.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals An integrated cell isolation and purification method for rat dorsal root ganglion neurons

2019 ◽  
Vol 47 (7) ◽  
pp. 3253-3260
Author(s):  
Huaishuang Shen ◽  
Minfeng Gan ◽  
Huilin Yang ◽  
Jun Zou
Keyword(s):  
Neuropathic Pain ◽  
Dorsal Root Ganglion ◽  
Primary Culture ◽  
Dorsal Root ◽  
Cell Isolation ◽  
Dorsal Root Ganglion Neurons ◽  
Drg Neurons ◽  
Purification Method ◽  
Isolation And Purification ◽  
Ganglion Neurons

Objective Neurobiology studies are increasingly focused on the dorsal root ganglion (DRG), which plays an important role in neuropathic pain. Existing DRG neuron primary culture methods have considerable limitations, including challenging cell isolation and poor cell yield, which cause difficulty in signaling pathway studies. The present study aimed to establish an integrated primary culture method for DRG neurons. Methods DRGs were obtained from fetal rats by microdissection, and then dissociated with trypsin. The dissociated neurons were treated with 5-fluorouracil to promote growth of neurons from the isolated cells. Then, reverse transcription polymerase chain reaction and immunofluorescence assays were used to identify and purify DRG neurons. Results Isolated DRGs were successfully dissociated and showed robust growth as individual DRG neurons in neurobasal medium. Both mRNA and protein assays confirmed that DRG neurons expressed neurofilament-200 and neuron-specific enolase. Conclusions Highly purified, stable DRG neurons could be easily harvested and grown for extended periods by using this integrated cell isolation and purification method, which may help to elucidate the mechanisms underlying neuropathic pain.

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