TY - JOUR
T1 - Modulation of trigeminal primary afferent activity in rats with chronic constriction nerve injury of the infraorbital nerve
AU - Kitagawa, Junichi
AU - Takeda, Mamoru
AU - Tsuboi, Yoshiyuki
AU - Suzuki, Ikuko
AU - Kadoi, Jun
AU - Matsumoto, Shigeji
AU - Iwata, Koichi
PY - 2008/2
Y1 - 2008/2
N2 - In order to clarify the involvement of primary afferent neurons in neuropathic pain in the trigeminal region, a model involving chronic constriction nerve injury of the infraorbital nerve (ION-CCI) was developed in rats. Mechano-allodynia was observed 3 days after ION-CCI and lasted more than 14 days. At 3, 5, 7, and 14 days after ION-CCI, single unit activities were recorded from the ION. Aβ-, Aδ-, and C-units were identified on the basis of their conduction velocity Aδ-units were frequently encountered at the late period after ION-CCI. The highest spontaneous activity was recorded 3 days after ION-CCI during the observation period, and it progressively decreased after that. Mechanically evoked responses of Aδ-units were also highest 3 days after ION-CCI, and gradually decreased thereafter. Patch-clamp recording was performed on middle-to-large sized trigeminal ganglion (TRG) neurons. Patch-clamp recording analysis revealed that Ik (sustained) and IA (transient) currents in rats with ION-CCI were significantly smaller than those in naïve rats. The hyperpolarization -activated current (Ih) was significantly larger in TRG neurons of rats with ION-CCI compared to that of naïve rats. These results suggest that Ih, Ik and IA currents in Aδ - TRG neurons are involved in mechano - allodynia in the trigeminal region following peripheral nerve injury.
AB - In order to clarify the involvement of primary afferent neurons in neuropathic pain in the trigeminal region, a model involving chronic constriction nerve injury of the infraorbital nerve (ION-CCI) was developed in rats. Mechano-allodynia was observed 3 days after ION-CCI and lasted more than 14 days. At 3, 5, 7, and 14 days after ION-CCI, single unit activities were recorded from the ION. Aβ-, Aδ-, and C-units were identified on the basis of their conduction velocity Aδ-units were frequently encountered at the late period after ION-CCI. The highest spontaneous activity was recorded 3 days after ION-CCI during the observation period, and it progressively decreased after that. Mechanically evoked responses of Aδ-units were also highest 3 days after ION-CCI, and gradually decreased thereafter. Patch-clamp recording was performed on middle-to-large sized trigeminal ganglion (TRG) neurons. Patch-clamp recording analysis revealed that Ik (sustained) and IA (transient) currents in rats with ION-CCI were significantly smaller than those in naïve rats. The hyperpolarization -activated current (Ih) was significantly larger in TRG neurons of rats with ION-CCI compared to that of naïve rats. These results suggest that Ih, Ik and IA currents in Aδ - TRG neurons are involved in mechano - allodynia in the trigeminal region following peripheral nerve injury.
KW - Neuropathic pain
KW - Trigeminal nerve
KW - Whisker pad
UR - http://www.scopus.com/inward/record.url?scp=40949085707&partnerID=8YFLogxK
U2 - 10.2330/joralbiosci.50.45
DO - 10.2330/joralbiosci.50.45
M3 - Review article
AN - SCOPUS:40949085707
SN - 1349-0079
VL - 50
SP - 45
EP - 50
JO - Journal of Oral Biosciences
JF - Journal of Oral Biosciences
IS - 1
ER -