Fukuyama Kouji, Fukuzawa Masashi, Okubo Ruri, Okada Motohiro
Department of Neuropsychiatry, Division of Neuroscience, Graduate School of Medicine, Mie University, Tsu, Mie 514-8507, Japan.
Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8560, Japan.
Pharmaceuticals (Basel). 2020 Mar 29;13(4):58. doi: 10.3390/ph13040058.
To study the pathomechanism and pathophysiology of autosomal dominant sleep-related hypermotor epilepsy (ADSHE), this study determined functional abnormalities of glutamatergic transmission in the thalamocortical motor pathway, from the reticular thalamic nucleus (RTN), motor thalamic nuclei (MoTN) tosecondary motor cortex (M2C) associated with the S286L-mutant α4β2-nicotinic acetylcholine receptor (nAChR) and the connexin43 (Cx43) hemichannel of transgenic rats bearing the rat S286L-mutant gene (S286L-TG), which corresponds to the human S284L-mutant gene using multiprobe microdialysis, primary cultured astrocytes and a Simple Western system. Expression of Cx43 in the M2C plasma membrane fraction of S286L-TG was upregulated compared with wild-type rats. Subchronic nicotine administration decreased Cx43 expression of wild-type, but did not affect that of S286L-TG; however, zonisamide (ZNS) decreased Cx43 in both wild-type and S286L-TG. Primary cultured astrocytes of wild-type were not affected by subchronic administration of nicotine but was decreased by ZNS. Upregulated Cx43 enhanced glutamatergic transmission during both resting and hyperexcitable stages in S286L-TG. Furthermore, activation of glutamatergic transmission associated with upregulated Cx43 reinforced the prolonged Cx43 hemichannel activation. Subchronic administration of therapeutic-relevant doses of ZNS compensated the upregulation of Cx43 and prolonged reinforced activation of Cx43 hemichannel induced by physiological hyperexcitability during the non-rapid eye movement phase of sleep. The present results support the primary pathomechanisms and secondary pathophysiology of ADSHE seizures of patients with S284L-mutation.
为研究常染色体显性遗传性睡眠相关运动过多性癫痫（ADSHE）的发病机制和病理生理学，本研究利用多探针微透析、原代培养星形胶质细胞和简单蛋白质免疫印迹系统，确定了与携带大鼠S286L突变基因（S286L-TG）的转基因大鼠的S286L突变α4β2-烟碱型乙酰胆碱受体（nAChR）和连接蛋白43（Cx43）半通道相关的，从丘脑网状核（RTN）、运动丘脑核（MoTN）到次级运动皮层（M2C）的丘脑皮质运动通路中谷氨酸能传递的功能异常。与野生型大鼠相比，S286L-TG的M2C质膜部分中Cx43的表达上调。亚慢性尼古丁给药降低了野生型大鼠的Cx43表达，但对S286L-TG大鼠没有影响；然而，唑尼沙胺（ZNS）降低了野生型和S286L-TG大鼠的Cx43表达。野生型原代培养星形胶质细胞不受亚慢性尼古丁给药的影响，但受ZNS给药的影响。S286L-TG大鼠中上调的Cx43在静息和过度兴奋阶段均增强了谷氨酸能传递。此外，与上调的Cx43相关的谷氨酸能传递激活加强了Cx43半通道的延长激活。治疗相关剂量的ZNS亚慢性给药补偿了Cx43的上调，并延长了睡眠非快速眼动期生理过度兴奋诱导的Cx43半通道的增强激活。本研究结果支持了S284L突变患者ADSHE发作的主要发病机制和继发性病理生理学。
