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標題: | 綠茶萃取物對初級培養大鼠胚胎神經細胞興奮性質的影響 Effects of Green Tea Extracts on the Excitability of Primary Cultured Rat Embryonic Neuron |
作者: | Yong-Cyuan Chen 陳勇全 |
指導教授: | 潘建源(Chien-Yuan Pan) |
關鍵字: | 綠茶,神經細胞,鈉離子通道, green tea,neuron,sodium channel, |
出版年 : | 2006 |
學位: | 碩士 |
摘要: | 從綠茶中萃取出來的多酚化合物主要有四種成份:(–)-epigallocatechin gallate
(EGCG), (–)-epigallocatechin (EGC), (–)-epicatechin gallate (ECG), and (–)-epicatechin (EC)。這些多酚已經被證實能夠抑制癌細胞的生長,防止神經退 化性疾病的形成,甚至能減少許多疾病的產生風險,像是中風、肥胖、心血管疾 病和老化。為了探討綠茶多酚對初級培養大鼠胚胎神經細胞的興奮性質有何影 響,我們利用全細胞膜片箝制技術去記錄離子通道電流和動作電位。研究結果顯 示ECG 減慢了電壓調控型鈉離子通道的不活化速率,而EC50 為12.88 ± 0.73 μM,同時此反應是可逆轉的;然而EGCG 卻沒有同樣的作用。鈉離子通道的不 活化恆穩態曲線也被ECG從-41.67 ± 0.08 毫伏特向負極移動到 -45.15 ± 0.05 毫 伏特。另外鈉離子通道從關閉狀態的恢復速率時間常數也從3.91 ± 0.08 毫秒延 長到 7.74 ± 0.43 毫秒。利用全細胞膜電流箝制技術記錄動作電位,ECG 會將電 作電位的強度和半寬分別從原先的96.5 ± 0.5 毫伏特和3.17 ± 0.13 毫秒增加到 103.9 ± 0.3 毫伏特和7.07 ± 0.12 毫秒,但是動作電位產生的頻率卻從16.4 ± 1.2 赫茲降到 6.6 ± 0.8 赫茲。這些研究結果顯示ECG 會經由影響鈉離子通道的性質 進一步改變神經細胞動作電位的產生,因而改變神經細胞的興奮性質。 ABSTRACT Polyphenols extracted from green tea (Camellia sinensis) is composed of four major chemicals: (–)-epigallocatechin gallate (EGCG), (–)-epigallocatechin (EGC), (–)-epicatechin gallate (ECG), and (–)-epicatechin (EC). These polyphenols have been shown to inhibit the growth of tumor cells, prevent neurodegenerative diseases, and reduce the risk of a series of illnesses, such as stroke, obesity, cardiovascular diseases, and aging. To study the effects of polyophenols on the excitability of primary cultured rat embryonic cortical neurons, whole-cell patch-clamp recording was used to monitor the ionic currents and action potential firing. The result showed that ECG reversibly slowed the inactivation of voltage-gated sodium channels with an EC50 of 12.88 ± 0.73 μM; however, EGCG did not have any effect on Na+ current. The steady-state inactivation of Na+ channel was negatively shifted from -41.67 ± 0.08 to -45.15 ± 0.05 mV and the time constant required for the recovery of Na+ channel to close state was prolonged from 3.91 ± 0.08 to 7.74 ± 0.43 ms by ECG. When action potentials were elicited under current clamp mode, the amplitude and half-width were increased from 96.5 ± 0.5 to 103.9 ± 0.3 mV and 3.17 ± 0.13 to 7.07 ± 0.12 ms, respectively; but frequency was decreased from 16.4 ± 1.2 to 6.6 ± 0.8 Hz. The results suggest that ECG may modulate excitability of neurons through altering sodium channels. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/33333 |
全文授權: | 有償授權 |
顯示於系所單位: | 動物學研究所 |
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