Wang Jianping, Lu Zhengfang, Fu Xiaojie, Zhang Di, Yu Lie, Li Nan, Gao Yufeng, Liu Xianliang, Yin Chunmao, Ke Junji, Li Liyuan, Zhai Mengmeng, Wu Shiwen, Fan Jiahong, Lv Liang, Liu Junchao, Chen Xuemei, Yang Qingwu, Wang Jian
Department of Neurology, The Fifth Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, 450052, China.
Department of Human Anatomy, College of Basic Medical Sciences, Zhengzhou University, Zhengzhou, Henan, 450000, China.
Transl Stroke Res. 2017 May 27. doi: 10.1007/s12975-017-0541-7.
Choline acetyltransferase-positive (ChAT) neurons within the subventricular zone (SVZ) have been shown to promote neurogenesis after stroke in mice by secreting acetylcholine (ACh); however, the mechanisms remain unclear. Receptors known to bind ACh include the nicotinic ACh receptors (nAChRs), which are present in the SVZ and have been shown to be important for cell proliferation, differentiation, and survival. In this study, we investigated the neurogenic role of the alpha-7 nAChR (α7 nAChR) in a mouse model of middle cerebral artery occlusion (MCAO) by using α7 nAChR inhibitor methyllycaconitine. Mice subjected to MCAO exhibited elevated expression of cytomembrane and nuclear fibroblast growth factor receptor 1 (FGFR1), as well as increased expression of PI3K, pAkt, doublecortin (DCX), polysialylated - neuronal cell adhesion molecule (PSA-NCAM), and mammalian achaete-scute homolog 1 (Mash1). MCAO mice also had more glial fibrillary acidic protein (GFAP)/5-bromo-2'-deoxyuridine (BrdU)-positive cells and DCX-positive cells in the SVZ than did the sham-operated group. Methyllycaconitine treatment increased cytomembrane FGFR1 expression and GFAP/BrdU-positive cells, upregulated the levels of phosphoinositide 3-kinase (PI3K) and phospho-Akt (pAkt), decreased nuclear FGFR1 expression, decreased the number of DCX-positive cells, and reduced the levels of DCX, PSA-NCAM, and Mash1 in the SVZ of MCAO mice compared with levels in vehicle-treated MCAO mice. MCAO mice treated with α7 nAChR agonist PNU-282987 exhibited the opposite effects. Our data show that α7 nAChR may decrease the proliferation of neural stem cells and promote differentiation of existing neural stem cells after stroke. These results identify a new mechanism of SVZ ChAT neuron-induced neurogenesis.
脑室下区（SVZ）内的胆碱乙酰转移酶阳性（ChAT）神经元已被证明可通过分泌乙酰胆碱（ACh）来促进小鼠中风后的神经发生；然而，其机制仍不清楚。已知与ACh结合的受体包括烟碱型ACh受体（nAChRs），其存在于SVZ中，并已被证明对细胞增殖、分化和存活很重要。在本研究中，我们通过使用α7 nAChR抑制剂甲基lycaconitine研究了α7 nAChR在大脑中动脉闭塞（MCAO）小鼠模型中的神经发生作用。接受MCAO的小鼠表现出细胞膜和细胞核成纤维细胞生长因子受体1（FGFR1）表达升高，以及PI3K、pAkt、双皮质素（DCX）、多唾液酸 - 神经细胞黏附分子（PSA-NCAM）和哺乳动物achaete-scute同源物1（Mash1）表达增加。与假手术组相比，MCAO小鼠在SVZ中也有更多的胶质纤维酸性蛋白（GFAP）/5-溴-2'-脱氧尿苷（BrdU）阳性细胞和DCX阳性细胞。与用载体处理的MCAO小鼠相比，甲基lycaconitine处理增加了细胞膜FGFR1表达和GFAP/BrdU阳性细胞，上调了磷酸肌醇3激酶（PI3K）和磷酸化Akt（pAkt）水平，降低了细胞核FGFR1表达，减少了DCX阳性细胞数量，并降低了MCAO小鼠SVZ中DCX、PSA-NCAM和Mash1的水平。用α7 nAChR激动剂PNU-282987处理的MCAO小鼠表现出相反的效果。我们的数据表明，α7 nAChR可能会减少中风后神经干细胞的增殖并促进现有神经干细胞的分化。这些结果确定了SVZ ChAT神经元诱导神经发生的新机制。
