17.High School English Listening

If you've ever had major surgery, you probably remember lying down and waking up–but nothing inbetween.
Thanks to the anesthesiologist, during the actual surgery you were out of it: immobilized andinsensitive to pain.
But until recently scientists had little understanding of how anesthetics actually work on the cellular level.
That's changed thanks to recent experiments performed by researchers at the University of Zurich, in Switzerland.
They knew that anesthetics caused pain receptors in the brain to turn off by acting likemost drugs do:
anesthetizing drugs attach to particular sites on nerve cells and turn them off.
Thequestion was, where on nerve cells do these drugs attach?
Nerve cell membranes have receptors for different kinds of chemicals produced by the brain.
Gamma-amino butyric acid, or GABA, for example, is a chemical thatshuts down nerve cells.
The hypothesis was that general anesthesia works by binding to GABAreceptors on a nerve cell, thereby activating the receptor and instructing the cell to shut down.
So itmade sense for the Zurich researchers to focus on GABA receptors.
To do this they worked with mice that had been genetically engineered to have nerve cells with GABA receptors that wouldn't respond to anesthetics.
And sure enough, when such mice were givenanesthetic drugs they weren't nearly as immune to pain as regular mice that had also been given pain-blocking drugs.
Clearly, GABA receptor sites on nerve cells are part of what allows anesthetics to dotheir job.
While the Zurich experiment fills in only one piece of the puzzle, it is an important step towards learning how these amazing drugs work, and how to make them even better.
译文：
如果你曾经做过大手术，你可能记得躺下和醒来，但中间没有什么。
多亏了麻醉师，在实际的手术过程中，你是不在状态的：被固定住，对疼痛不敏感。
但直到最近，科学家们对麻醉剂在细胞水平上的实际作用了解甚少。
由于瑞士苏黎世大学的研究人员最近进行的实验，这种情况已经改变。
他们知道，麻醉剂通过像大多数药物一样的作用，使大脑中的疼痛受体关闭。
麻醉药附着在神经细胞的特定部位并使其关闭。
问题是，这些药物附着在神经细胞的什么地方？
神经细胞膜对大脑产生的不同种类的化学物质都有受体。
例如，γ-氨基丁酸，或称GABA，是一种使神经细胞关闭的化学物质。
假设是，全身麻醉通过与神经细胞上的GABA受体结合而发挥作用，从而激活受体并指示细胞关闭。
因此，苏黎世的研究人员将重点放在GABA受体上是有意义的。
为了做到这一点，他们使用了经过基因改造的小鼠，这些小鼠的神经细胞具有GABA受体，对麻醉剂没有反应。
果然，当这种小鼠被给予麻醉药物时，它们对疼痛的免疫力远不如同样被给予阻断疼痛药物的普通小鼠。
显然，神经细胞上的GABA受体部位是使麻醉剂发挥其作用的部分原因。
虽然苏黎世的实验只是填补了拼图中的一个部分，但它是朝着了解这些神奇药物如何工作以及如何使它们变得更好迈出的重要一步。
重点词汇：
lying down 拒绝履行契约
Thanks to 幸亏;归因于
out of it 〈口〉因被排斥在某集体之外而感到难过
different kinds of 不同种类的 ; 各种各样的 ; 各种不同类型的
butyric acid 丁酸；酪酸