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  3. In the 1950s, the development of antipsychotic drugs called neuroleptics(抑制精神病药物)radically changed the clinical outlook for pati

In the 1950s, the development of antipsychotic drugs called neuroleptics(抑制精神病药物)radically changed the clinical outlook for pati

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问题    In the 1950s, the development of antipsychotic drugs called neuroleptics(抑制精神病药物)radically changed the clinical outlook for patients in mental institutions who had previously been considered hopelessly psychotic.  Daily medication controlled delusions and made psychotherapy possible. Many who otherwise might never have left institutions returned to society. Now physicians have learned that there is a price to be paid for these benefits. Approximately 10 to 15 percent of patients who undergo long-term treatment with antipsychotic drugs develop a cluster of symptoms called tardive dyskinesia(迟发性运动障碍 ), the most common symptoms of which are involuntary repetitive movement of the tongue, mouth, and face, and sometimes the limbs and trunk.
   Neuroleptic drugs interfere with the action of dopamine (多巴胺), an important neurotransmitter in the brain, by binding to the dopamine receptors of nerve cells, and dopamine is a prime suspect in the pathophysiology of schizophrenia. Large doses of drugs such as amphetamines(苯丙胺), which stimulate secretion of dopamine, produce a psychosis resembling schizophrenia.  Reducing the activity of this neurotransmitter alleviates the delusions that cause psychotic behavior. Although the inhibition of dopamine activity can control psychotic behavior, researchers now believe that the central nervous system of some patients adapts to long-term therapy by increasing the number of specific dopamine binding sites. The net result is dopamine hypersensitivity which is correlated with the subsequent appearance of tardive dyskinesia.
   The risk of developing tardive dyskinesia is not so great that doctors have considered abandoning the use of antipsychotic drugs. Patients generally are bothered only slightly by the physical side effects, though the abnormal movements are troubling and may hinder social adjustment. Additionally, early diagnosis and prompt discontinuation of the neuroleptics might decrease the incidence of the movement disorders. Unfortunately, without neuroleptic drugs, psychotic behavior returns. So researchers have tried to achieve a satisfactory balance between the two effects, lowering dosage to a level that minimizes movement disorders yet control psychosis. In a five-year study of twenty-seven psychiatric patients treated with neuroleptics representing all classes of antipsychotic drugs, researchers attempted to decrease drug doses to their lowest effective levels. Patient responses suggested that low to moderate doses of antipsychotic drugs could control psychoses just as well as high doses, and tardive dyskinesia symptoms stabilized and gradually diminished or completely disappeared.
   The fact that psychoses can be controlled at the same time that tardive dyskensia symptoms are reduced suggests that a drug more specifically affecting the mechanism of psychoses might not cause movement disorders. Sulpiride, a drug not available in the United States but widely used in Europe, where it was developed, may be one such alternative. The drug selectively blocks D-2 dopamine receptors, perhaps especially those in the limbic area of the brain, which is involved in emotion and behavior.  It does not adversely affect the adenylate ( 腺苷酸) cyclase ( 环化酶 )-linked D -1 dopamine receptors. Sulpiride has proven effective in the short term, but whether it suppresses tardive dyskenesia over a long period of treatment is not yet known.
It can be inferred that neuroleptic drugs control psychosis by______.
选项 A、suppressing the production of dopamine in the brain
B、blocking the nerve impulses transmitted to the muscles
C、preventing the absorption of dopamine by brain cells
D、creating a hypersensitivity to dopamine
答案C
解析 问题中的单词inferred表示这是一个推论题。作者没有告诉我们neuroleptic drugs的具体特征及药性机理，但是我们可以从文中归纳出一些这方面的特性。第二段描述了这种药物的功能，可以干扰the action of dopamine by binding to the dopamine receptors。由此我们可以推断这种药物覆盖了receptors，这样dopamine就不能被brain cells所吸收。这就是C所讲到的内容。A是错的。文章没有讲到dopamine的数量减少(suppressed)，而是说使存在的dopamine不起作用。B中的blocking这个词是课文中的，容易使人受到误导，neuroleptic drugs确是block the absorption of dopamine by the nerve cells，但不是“block”“the nerve impulses transmitted to the muscles”。D也是错的，因为这是一种副作用，不是控制psychosis的方法。
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