Alteration of primary afferent activity following inferior alveolar nerve transection in rats

Kazuharu Nakagawa; Mamoru Takeda; Yoshiyuki Tsuboi; Masahiro Kondo; Junichi Kitagawa; Shigeji Matsumoto; Azusa Kobayashi; Barry J. Sessle; Masamichi Shinoda; Koichi Iwata

doi:10.1186/1744-8069-6-9

Alteration of primary afferent activity following inferior alveolar nerve transection in rats

Kazuharu Nakagawa, Mamoru Takeda, Yoshiyuki Tsuboi, Masahiro Kondo, Junichi Kitagawa, Shigeji Matsumoto, Azusa Kobayashi, Barry J. Sessle, Masamichi Shinoda, Koichi Iwata

School of Dentistry

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Abstract

Background: In order to evaluate the neural mechanisms underlying the abnormal facial pain that may develop following regeneration of the injured inferior alveolar nerve (IAN), the properties of the IAN innervated in the mental region were analyzed.Results: Fluorogold (FG) injection into the mental region 14 days after IAN transection showed massive labeling of trigeminal ganglion (TG). The escape threshold to mechanical stimulation of the mental skin was significantly lower (i.e. mechanical allodynia) at 11-14 days after IAN transection than before surgery. The background activity, mechanically evoked responses and afterdischarges of IAN Aδ-fibers were significantly higher in IAN-transected rats than naive. The small/medium diameter TG neurons showed an increase in both tetrodotoxin (TTX)-resistant (TTX-R) and -sensitive (TTX-S) sodium currents (I_Na) and decrease in total potassium current, transient current (I_A) and sustained current (I_K) in IAN-transected rats. The amplitude, overshoot amplitude and number of action potentials evoked by the depolarizing pulses after 1 μM TTX administration in TG neurons were significantly higher, whereas the threshold current to elicit spikes was smaller in IAN-transected rats than naive. Resting membrane potential was significantly smaller in IAN-transected rats than that of naive.Conclusions: These data suggest that the increase in both TTX-S I_Naand TTX-R I_Naand the decrease in I_Aand I_kin small/medium TG neurons in IAN-transected rats are involved in the activation of spike generation, resulting in hyperexcitability of Aδ-IAN fibers innervating the mental region after IAN transection.

Original language	English
Article number	9
Journal	Molecular Pain
Volume	6
DOIs	https://doi.org/10.1186/1744-8069-6-9
Publication status	Published - 3 Feb 2010

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@article{3ac76985919f46a58ed5e600324699ec,

title = "Alteration of primary afferent activity following inferior alveolar nerve transection in rats",

abstract = "Background: In order to evaluate the neural mechanisms underlying the abnormal facial pain that may develop following regeneration of the injured inferior alveolar nerve (IAN), the properties of the IAN innervated in the mental region were analyzed.Results: Fluorogold (FG) injection into the mental region 14 days after IAN transection showed massive labeling of trigeminal ganglion (TG). The escape threshold to mechanical stimulation of the mental skin was significantly lower (i.e. mechanical allodynia) at 11-14 days after IAN transection than before surgery. The background activity, mechanically evoked responses and afterdischarges of IAN Aδ-fibers were significantly higher in IAN-transected rats than naive. The small/medium diameter TG neurons showed an increase in both tetrodotoxin (TTX)-resistant (TTX-R) and -sensitive (TTX-S) sodium currents (INa) and decrease in total potassium current, transient current (IA) and sustained current (IK) in IAN-transected rats. The amplitude, overshoot amplitude and number of action potentials evoked by the depolarizing pulses after 1 μM TTX administration in TG neurons were significantly higher, whereas the threshold current to elicit spikes was smaller in IAN-transected rats than naive. Resting membrane potential was significantly smaller in IAN-transected rats than that of naive.Conclusions: These data suggest that the increase in both TTX-S INa and TTX-R INa and the decrease in IA and Ik in small/medium TG neurons in IAN-transected rats are involved in the activation of spike generation, resulting in hyperexcitability of Aδ-IAN fibers innervating the mental region after IAN transection.",

author = "Kazuharu Nakagawa and Mamoru Takeda and Yoshiyuki Tsuboi and Masahiro Kondo and Junichi Kitagawa and Shigeji Matsumoto and Azusa Kobayashi and Sessle, {Barry J.} and Masamichi Shinoda and Koichi Iwata",

year = "2010",

month = feb,

day = "3",

doi = "10.1186/1744-8069-6-9",

language = "English",

volume = "6",

journal = "Molecular Pain",

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T1 - Alteration of primary afferent activity following inferior alveolar nerve transection in rats

AU - Nakagawa, Kazuharu

AU - Takeda, Mamoru

AU - Tsuboi, Yoshiyuki

AU - Kondo, Masahiro

AU - Kitagawa, Junichi

AU - Matsumoto, Shigeji

AU - Kobayashi, Azusa

AU - Sessle, Barry J.

AU - Shinoda, Masamichi

AU - Iwata, Koichi

PY - 2010/2/3

Y1 - 2010/2/3

N2 - Background: In order to evaluate the neural mechanisms underlying the abnormal facial pain that may develop following regeneration of the injured inferior alveolar nerve (IAN), the properties of the IAN innervated in the mental region were analyzed.Results: Fluorogold (FG) injection into the mental region 14 days after IAN transection showed massive labeling of trigeminal ganglion (TG). The escape threshold to mechanical stimulation of the mental skin was significantly lower (i.e. mechanical allodynia) at 11-14 days after IAN transection than before surgery. The background activity, mechanically evoked responses and afterdischarges of IAN Aδ-fibers were significantly higher in IAN-transected rats than naive. The small/medium diameter TG neurons showed an increase in both tetrodotoxin (TTX)-resistant (TTX-R) and -sensitive (TTX-S) sodium currents (INa) and decrease in total potassium current, transient current (IA) and sustained current (IK) in IAN-transected rats. The amplitude, overshoot amplitude and number of action potentials evoked by the depolarizing pulses after 1 μM TTX administration in TG neurons were significantly higher, whereas the threshold current to elicit spikes was smaller in IAN-transected rats than naive. Resting membrane potential was significantly smaller in IAN-transected rats than that of naive.Conclusions: These data suggest that the increase in both TTX-S INa and TTX-R INa and the decrease in IA and Ik in small/medium TG neurons in IAN-transected rats are involved in the activation of spike generation, resulting in hyperexcitability of Aδ-IAN fibers innervating the mental region after IAN transection.

AB - Background: In order to evaluate the neural mechanisms underlying the abnormal facial pain that may develop following regeneration of the injured inferior alveolar nerve (IAN), the properties of the IAN innervated in the mental region were analyzed.Results: Fluorogold (FG) injection into the mental region 14 days after IAN transection showed massive labeling of trigeminal ganglion (TG). The escape threshold to mechanical stimulation of the mental skin was significantly lower (i.e. mechanical allodynia) at 11-14 days after IAN transection than before surgery. The background activity, mechanically evoked responses and afterdischarges of IAN Aδ-fibers were significantly higher in IAN-transected rats than naive. The small/medium diameter TG neurons showed an increase in both tetrodotoxin (TTX)-resistant (TTX-R) and -sensitive (TTX-S) sodium currents (INa) and decrease in total potassium current, transient current (IA) and sustained current (IK) in IAN-transected rats. The amplitude, overshoot amplitude and number of action potentials evoked by the depolarizing pulses after 1 μM TTX administration in TG neurons were significantly higher, whereas the threshold current to elicit spikes was smaller in IAN-transected rats than naive. Resting membrane potential was significantly smaller in IAN-transected rats than that of naive.Conclusions: These data suggest that the increase in both TTX-S INa and TTX-R INa and the decrease in IA and Ik in small/medium TG neurons in IAN-transected rats are involved in the activation of spike generation, resulting in hyperexcitability of Aδ-IAN fibers innervating the mental region after IAN transection.

UR - http://www.scopus.com/inward/record.url?scp=77649096167&partnerID=8YFLogxK

U2 - 10.1186/1744-8069-6-9

DO - 10.1186/1744-8069-6-9

M3 - Article

C2 - 20122287

AN - SCOPUS:77649096167

SN - 1744-8069

VL - 6

JO - Molecular Pain

JF - Molecular Pain

M1 - 9

ER -

Alteration of primary afferent activity following inferior alveolar nerve transection in rats

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