Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
Osaka Institute of Public Health, 1-3-69 Nakamichi, Higashinari-ku, Osaka 537-0025, Japan.
Exp Anim. 2020 Nov 12;69(4):388-394. doi: 10.1538/expanim.20-0025. Epub 2020 Jun 5.
We recently demonstrated that aspartoacylase (Aspa) and hyperpolarization-activated cyclic nucleotide-gated potassium channel 1 (Hcn1) genes were causative of essential tremor (ET) in rats. This finding was obtained using Aspa/Hcn1 double-mutant rats, but they were bred on a heterogeneous genetic background of two strains, F344 and WTC. Here, we developed an Aspa/Hcn1 double-knockout rat strain with a homogenous F344 genetic background and studied the ability of glutamate receptor antagonists to suppress ET. The F344-Aspa/Hcn1 double-knockout rats exhibited spontaneous, intense body tremor equivalent to that in the double-mutant rats. N-acetyl-aspartate (NAA), a substrate of ASPA, showed accumulation in all brain regions and in the spinal cord. However, N-acetyl-aspartyl-glutamate (NAAG), which is derived from NAA and interacts with glutamatergic receptors, was decreased in the medulla oblongata of the double-knockout rats. The tremor was suppressed by 3-[(R)-2-carboxypiperazin-4-yl]-prop-2-enyl-1-phosphonic acid, an N-methyl-D-aspartate (NMDA) receptor antagonist, in F344-Aspa/Hcn1 double-knockout rats. The non-NMDA glutamate receptor antagonist NBQX weakly inhibited the tremor, while the metabotropic glutamate receptor antagonist LY341495 showed no effect. In addition, both NR2B subunit-specific (Ro 25-6981) and NR2C/NR2D subunit-specific (cis-piperidine dicarboxylic acid) NMDA receptor antagonists suppressed the tremor. These data indicated that the pathogenesis of tremor in Aspa/Hcn1 double-knockout rats involved ionotropic glutamate receptors, particularly NMDA receptors.
我们最近证明天冬氨酸酶 (Aspa) 和超极化激活环核苷酸门控钾通道 1 (Hcn1) 基因是导致大鼠特发性震颤 (ET) 的原因。这一发现是使用 Aspa/Hcn1 双突变大鼠获得的，但它们是在 F344 和 WTC 两个品系的异质遗传背景下繁殖的。在这里，我们开发了一种具有同质 F344 遗传背景的 Aspa/Hcn1 双敲除大鼠品系，并研究了谷氨酸受体拮抗剂抑制 ET 的能力。F344-Aspa/Hcn1 双敲除大鼠表现出自发的、强烈的身体震颤，相当于双突变大鼠。N-乙酰天冬氨酸 (NAA)，ASP 的底物，在所有脑区和脊髓中积累。然而，来自 NAA 并与谷氨酸能受体相互作用的 N-乙酰天冬氨酰谷氨酸 (NAAG) 在双敲除大鼠的延髓中减少。3-[(R)-2-羧基哌嗪-4-基]-丙烯基-1-膦酸，一种 N-甲基-D-天冬氨酸 (NMDA) 受体拮抗剂，可抑制 F344-Aspa/Hcn1 双敲除大鼠的震颤。非 NMDA 谷氨酸受体拮抗剂 NBQX 对震颤有较弱的抑制作用，而代谢型谷氨酸受体拮抗剂 LY341495 则没有作用。此外，NR2B 亚基特异性 (Ro 25-6981) 和 NR2C/NR2D 亚基特异性 (顺式-哌啶二羧酸) NMDA 受体拮抗剂均可抑制震颤。这些数据表明，Aspa/Hcn1 双敲除大鼠震颤的发病机制涉及离子型谷氨酸受体，特别是 NMDA 受体。
