Huang F N, Zhang B L, Li W B, Cui X, Han Z T, Fang Z Y
Department of Neurobiology, Institute of Gerontology and Geriatrics, Chinese PLA General Hospital and Postgraduate Medical School, Beijing 100853, China.
Zhongguo Ying Yong Sheng Li Xue Za Zhi. 2001 May;17(2):109-12.
To investigate the effects of free radicals (FRs) and amyloid beta protein (A beta 1-40) on the functions of expressed neurotransmitter receptors (NRs) from rat brains in Xenopus oocytes.
Total RNA and Messenger RNA (mRNA) was prepared from 3-month-old Wistar rat brain tissues with Promega kits and microinjected into mature Xenopus oocytes (stage V - VI) with 50 nl (50 ng) for each oocyte for receptor expression and their currents were recorded with double electrode voltage clamp technique. Superoxide anion free radicals (SAFRs) and A beta 1-40 was added 12 h, 24 h, 96 h to incubation solution before recording.
The results showed that oocytes expressed mACh, glutamate, dopamine, serotonin and gamma-aminobutyric acid receptors. The current characteristics of these receptors were inward currents carried by chloride ion with their equilibrium potentials close to - 22 mV. A beta 1-40 and free radicals had a kind of inhibitory effect on the expressed GluR. When treated with 60 nmol/L A beta 1-40 over 24 h, the currents of GluR significantly decreased (25% off, P < :0.01). When oocytes were co-treated with 60 nmol/L A beta 1-40 and SAFRs over a period of 12 h, the currents of glutamate receptor significantly decreased (21% of P < 0.05), and the decreased percentage reached 52% over 24h co-treated with 60 nmol/L A beta 1-40 and SAFRs. Vitamin E had partial antagonistic effect against these effects.
The result suggests that A beta has a kind of inhibitory effects upon glutamate receptor, which is similar to those of free radicals. Their effects can be antagonized by vitamin E. This implies that A beta may play roles via inhibiting receptor function in pathophysiology of Alzheimer's disease.
研究自由基（FRs）和β淀粉样蛋白（Aβ1-40）对非洲爪蟾卵母细胞中大鼠脑源性神经递质受体（NRs）功能的影响。
用Promega试剂盒从3月龄Wistar大鼠脑组织中提取总RNA和信使RNA（mRNA），以50 nl（50 ng）的量显微注射到成熟的非洲爪蟾卵母细胞（V - VI期）中用于受体表达，并用双电极电压钳技术记录其电流。在记录前12小时、24小时、96小时向孵育液中加入超氧阴离子自由基（SAFRs）和Aβ1-40。
结果显示卵母细胞表达毒蕈碱型乙酰胆碱、谷氨酸、多巴胺、5-羟色胺和γ-氨基丁酸受体。这些受体的电流特征为氯离子介导的内向电流，其平衡电位接近-22 mV。Aβ1-40和自由基对表达的谷氨酸受体有抑制作用。用60 nmol/L Aβ1-40处理24小时以上，谷氨酸受体电流显著降低（降低25%，P<0.01）。当卵母细胞用60 nmol/L Aβ1-40和SAFRs共同处理12小时，谷氨酸受体电流显著降低（P<0.05，降低21%），在60 nmol/L Aβ1-40和SAFRs共同处理24小时时，降低百分比达到52%。维生素E对这些作用有部分拮抗作用。
结果表明Aβ对谷氨酸受体有抑制作用，类似于自由基。其作用可被维生素E拮抗。这意味着Aβ可能在阿尔茨海默病的病理生理过程中通过抑制受体功能发挥作用。
