尾懸垂による神経軸索Na+電流の障害 : 廃用性筋萎縮との関連の可能性
Sodium Current by Hindlimb Unloading
バンズライ, チメグルハム 徳島大学大学院医科学教育部（医学専攻）
Higashi, Saki Tokushima University
Okada, Ryo Tokushima University
Mori, Atsuko Tokushima University
島谷, 佳光 Tokushima University
Disuse neuromuscular atrophy
motor axonal excitability
persistent sodium current
This study aimed to characterize the excitability changes in peripheral motor axons caused by hindlimb unloading (HLU), which is a model of disuse neuromuscular atrophy. HLU was performed in normal 8-week-old male mice by fixing the proximal tail by a clip connected to the top of the animal's cage for 3 weeks. Axonal excitability studies were performed by stimulating the sciatic nerve at the ankle and recording the compound muscle action potential (CMAP) from the foot. The amplitudes of the motor responses of the unloading group were 51% of the control amplitudes [2.2 ± 1.3 mV (HLU) vs. 4.3 ± 1.2 mV (Control), P = 0.03]. Multiple axonal excitability analysis showed that the unloading group had a smaller strength-duration time constant (SDTC) and late subexcitability (recovery cycle) than the controls [0.075 ± 0.01 (HLU) vs. 0.12 ± 0.01 (Control), P < 0.01; 5.4 ± 1.0 (HLU) vs. 10.0 ± 1.3 % (Control), P = 0.01, respectively]. Three weeks after releasing from HLU, the SDTC became comparable to the control range. Using a modeling study, the observed differences in the waveforms could be explained by reduced persistent Na+ currents along with parameters related to current leakage. Quantification of RNA of a SCA1A gene coding a voltage-gated Na+ channel tended to be decreased in the sciatic nerve in HLU. The present study suggested that axonal ion currents are altered in vivo by HLU. It is still undetermined whether the dysfunctional axonal ion currents have any pathogenicity on neuromuscular atrophy or are the results of neural plasticity by atrophy.
Frontiers in Physiology
Frontiers Media S.A.
内容要旨・審査要旨 : LID201606101007.pdf
論文本文 : LID201606101008.pdf
本論文は, 著者Chimeglkham Banzraiの学位論文として提出され, 学位審査・授与の対象となっている。
Copyright: © 2016 Banzrai, Nodera, Kawarai, Higashi, Okada, Mori, Shimatani, Osaki and Kaji. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
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