Homostachydrine is a Xenobiotic Substrate of OCTN1/SLC22A4 and Potentially Sensitizes Pentylenetetrazole-Induced Seizures in Mice
Homostachydrine is a Xenobiotic Substrate of OCTN1/SLC22A4 and Potentially Sensitizes Pentylenetetrazole-Induced Seizures in Mice
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DOI：
10.1007/s11064-020-03118-8
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发表时间：
2020-08
影响因子：
4.4
通讯作者：
M. Nishiyama;N. Nakamichi;T. Yoshimura;Y. Masuo;Tomoe Komori;Takahiro Ishimoto;J. Matsuo;Y. Kato
中科院分区：
文献类型：
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作者：
M. Nishiyama;N. Nakamichi;T. Yoshimura;Y. Masuo;Tomoe Komori;Takahiro Ishimoto;J. Matsuo;Y. Kato
需要了解癫痫的潜在机制，因为一些患者无法控制其癫痫发作。肉毒碱/有机阳离子转运蛋白OCTN 1/SLC 22 A4在脑神经元中表达，并转运食物来源的抗氧化剂麦角硫因（ERGO）、左旋肉毒碱和精胺，所有这些都可能与癫痫有关。本研究旨在阐明这种转运蛋白与癫痫发作的可能联系。在戊四唑（PTZ）诱导的急性癫痫发作和点燃模型中，ocnt 1基因敲除小鼠（octn 1 −/−）的癫痫发作评分均低于野生型小鼠。在野生型小鼠的海马中观察到PTZ给药后癫痫相关基因c-fosandArc和神经营养因子BDNF的上调，但ctn 1 −/−小鼠没有。为了找到与癫痫发作相关的OCTN 1底物，使用液相色谱-四极杆飞行时间质谱法对两种菌株的海马、额叶皮质和血浆提取物进行了非靶向代谢组学分析，从而鉴定出植物生物碱高水苏碱作为存在于较低浓度inoctn 1 −/−小鼠中的化合物。在OCTN 1转染的HEK 293细胞中证实了OCTN 1介导的氘标记高水苏碱摄取，表明该化合物是OCTN 1的底物。高水苏碱给药增加PTZ诱导的急性癫痫发作评分和海马中Arcin的表达以及额叶皮层中Arc、Egr 1和BDNF的表达。相反，OCTN 1底物/抑制剂ERGO的施用抑制PTZ诱导的点燃并降低血浆高水苏碱浓度。因此，这些结果表明，OCTN 1至少部分与PTZ诱导的癫痫发作相关，这可能会因高水苏碱（一种新鉴定的食物来源的OCTN 1底物）治疗而恶化。
Understanding of the underlying mechanism of epilepsy is desired since some patients fail to control their seizures. The carnitine/organic cation transporter OCTN1/SLC22A4 is expressed in brain neurons and transports food-derived antioxidant ergothioneine (ERGO),l-carnitine, and spermine, all of which may be associated with epilepsy. This study aimed to clarify the possible association of this transporter with epileptic seizures. In both pentylenetetrazole (PTZ)-induced acute seizure and kindling models,ocnt1gene knockout mice (octn1−/−) showed lower seizure scores compared with wild-type mice. Up-regulation of the epilepsy-related genes,c-fosandArc,and the neurotrophic factor BDNF following PTZ administration was observed in the hippocampus of wild-type, but notoctn1−/−mice. To find the OCTN1 substrate associated with the seizure, untargeted metabolomics analysis using liquid chromatography–quadrupole time-of-flight mass spectrometry was conducted on extracts from the hippocampus, frontal cortex, and plasma of both strains, leading to the identification of a plant alkaloid homostachydrine as a compound present in a lower concentration inoctn1−/−mice. OCTN1-mediated uptake of deuterium-labeled homostachydrine was confirmed in OCTN1-transfected HEK293 cells, suggesting that this compound is a substrate of OCTN1. Homostachydrine administration increased PTZ-induced acute seizure scores and the expression ofArcin the hippocampus and that ofArc,Egr1, and BDNF in the frontal cortex. Conversely, administration of the OCTN1 substrate/inhibitor ERGO inhibited PTZ-induced kindling and reduced the plasma homostachydrine concentration. Thus, these results suggest that OCTN1 is at least partially associated with PTZ-induced seizures, which is potentially deteriorated by treatment with homostachydrine, a newly identified food-derived OCTN1 substrate.