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Electrophysiologic changes in dorsal root ganglion neurons and behavioral changes in a lumbar radiculopathy model.
Spine (Phila Pa 1976). 2007 Jan 15; 32(2):E65-72.S

Abstract

STUDY DESIGN

The DRG neuron was electrophysiologically investigated using a rat model with constriction of the proximal site of the DRG.

OBJECTIVES

To investigate the pathomechanisms of lumbar radiculopathy, we established a rat model with constriction of the proximal site of the DRG. And to characterize the DRG neurons in the rat model of lumbar radiculopathy, the physiologic properties regarding action potential, Na, and K current of the DRG neurons were analyzed through the use of patch clamp recordings.

SUMMARY OF BACKGROUND DATA

In lumbar root constriction models, properties of secondary afferent neurons in the dorsal horn have been investigated. However, the electrical properties of DRG neuron have not been well investigated.

METHODS

To compare the excitability of DRG neurons between root constriction models and sham, we examined the threshold current, action potential (AP) threshold, resting membrane potential (RMP), afterhyperpolarization (AHP), action potential duration 50 (APD50), action potential amplitude, maximum rise time of AP, and pattern of discharges evoked by depolarizing current. We also examined the peak Na current and steady-state Na and K currents with the voltage clamp technique.

RESULTS

The rats in the root constriction group demonstrated mechanical allodynia and thermal hyperalgesia. In measurement of the action potential, lower threshold current, more depolarized RMP, larger AHP, and prolonged APD50 were measured in the root constriction neurons compared with the sham group. The incidence of sustained burst was significantly higher in root constriction neurons. The Na current in root constriction neurons was markedly larger. There were no significant differences in K current density and voltage dependency.

CONCLUSIONS

The constriction of lumbar root increased excitability and Na current amplitude of DRG neurons. These findings indicate that lumbar radicular pain may be associated with increased excitability of involved DRG neurons.

Authors+Show Affiliations

Department of Orthopaedic Surgery, School of Medicine, Sapporo Medical University, Sapporo, Japan.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17224801

Citation

Kirita, Takashi, et al. "Electrophysiologic Changes in Dorsal Root Ganglion Neurons and Behavioral Changes in a Lumbar Radiculopathy Model." Spine, vol. 32, no. 2, 2007, pp. E65-72.
Kirita T, Takebayashi T, Mizuno S, et al. Electrophysiologic changes in dorsal root ganglion neurons and behavioral changes in a lumbar radiculopathy model. Spine (Phila Pa 1976). 2007;32(2):E65-72.
Kirita, T., Takebayashi, T., Mizuno, S., Takeuchi, H., Kobayashi, T., Fukao, M., Yamashita, T., & Tohse, N. (2007). Electrophysiologic changes in dorsal root ganglion neurons and behavioral changes in a lumbar radiculopathy model. Spine, 32(2), E65-72.
Kirita T, et al. Electrophysiologic Changes in Dorsal Root Ganglion Neurons and Behavioral Changes in a Lumbar Radiculopathy Model. Spine (Phila Pa 1976). 2007 Jan 15;32(2):E65-72. PubMed PMID: 17224801.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Electrophysiologic changes in dorsal root ganglion neurons and behavioral changes in a lumbar radiculopathy model. AU - Kirita,Takashi, AU - Takebayashi,Tsuneo, AU - Mizuno,Satoshi, AU - Takeuchi,Hirohito, AU - Kobayashi,Takeshi, AU - Fukao,Mitsuhiro, AU - Yamashita,Toshihiko, AU - Tohse,Noritsugu, PY - 2007/1/17/pubmed PY - 2007/2/7/medline PY - 2007/1/17/entrez SP - E65 EP - 72 JF - Spine JO - Spine (Phila Pa 1976) VL - 32 IS - 2 N2 - STUDY DESIGN: The DRG neuron was electrophysiologically investigated using a rat model with constriction of the proximal site of the DRG. OBJECTIVES: To investigate the pathomechanisms of lumbar radiculopathy, we established a rat model with constriction of the proximal site of the DRG. And to characterize the DRG neurons in the rat model of lumbar radiculopathy, the physiologic properties regarding action potential, Na, and K current of the DRG neurons were analyzed through the use of patch clamp recordings. SUMMARY OF BACKGROUND DATA: In lumbar root constriction models, properties of secondary afferent neurons in the dorsal horn have been investigated. However, the electrical properties of DRG neuron have not been well investigated. METHODS: To compare the excitability of DRG neurons between root constriction models and sham, we examined the threshold current, action potential (AP) threshold, resting membrane potential (RMP), afterhyperpolarization (AHP), action potential duration 50 (APD50), action potential amplitude, maximum rise time of AP, and pattern of discharges evoked by depolarizing current. We also examined the peak Na current and steady-state Na and K currents with the voltage clamp technique. RESULTS: The rats in the root constriction group demonstrated mechanical allodynia and thermal hyperalgesia. In measurement of the action potential, lower threshold current, more depolarized RMP, larger AHP, and prolonged APD50 were measured in the root constriction neurons compared with the sham group. The incidence of sustained burst was significantly higher in root constriction neurons. The Na current in root constriction neurons was markedly larger. There were no significant differences in K current density and voltage dependency. CONCLUSIONS: The constriction of lumbar root increased excitability and Na current amplitude of DRG neurons. These findings indicate that lumbar radicular pain may be associated with increased excitability of involved DRG neurons. SN - 1528-1159 UR - https://www.unboundmedicine.com/medline/citation/17224801/Electrophysiologic_changes_in_dorsal_root_ganglion_neurons_and_behavioral_changes_in_a_lumbar_radiculopathy_model_ L2 - https://doi.org/10.1097/01.brs.0000252202.85377.96 DB - PRIME DP - Unbound Medicine ER -