蘭陽盆地某國中學生神經傳導速度與飲水砷暴露及甲烯基四氫葉酸還原酵素基因多形性之相關性研究

A Study on the Association Between Nerve Conduction Velocity and Arsenic Exposure, and Genetic Polymorphism of Methylenetetrahydrofolate Reductase among Students of Junior High School in Lanyang Basin

鄭喜瑩(Teh Hee-Wen)

指導教授 ： 邱弘毅

臺北醫學大學/公共衛生暨營養學院/公共衛生學研究所/碩士(2000年)

摘要

砷在人體的解毒作用會與髓鞘的形成競爭甲基，導致神經傳導遲緩。本研究目的是希望能瞭解長期飲用含砷地下水是否會導致神經傳導速度減慢，以及與甲烯基四氫葉酸還原酵素(Methylenetetrahydrofolate reductase, MTHFR)基因多形性之間的相關性。研究對象從民國八十年於蘭陽盆地執行之世代追蹤研究的研究地區內，隨機選取一所國民中學，將學生基本資料和原有研究世代的井水所在地址比對，選出130名居住地址和井水所在地址相同的一、二年級學生為研究對象。研究對象的暴露資料來源，為該世代追蹤研究執行時所採地下水中測出的含砷濃度，以及問卷得知本研究之研究對象飲用地下水的年數、停喝年數，和每日喝水量。在神經傳導速度檢查部分，共檢測四條神經的運動傳導速度及三條神經的感覺傳導速度。運動傳導速度測量的神經包括手部之正中神經(median nerve)與尺神經(ulnar nerve) ，及腳部之腓神經(peroneal nerve)與脛神經(tibia nerve) ；感覺傳導速度測量的神經包括手部之正中神經(median nerve)與尺神經(ulnar nerve)，及腳部之腓腸神經(sural nerve)。MTHFR基因多形性是利用聚合酵素連鎖反應為基礎的限制片段長度多形性(PCR-RFLP)進行分析，檢測出本研究族群帶有突變T鹽基的頻率為0.27。研究結果發現，在控制性別、身高等危險因子後，停喝含砷地下水年數越高者，其正中神經及尺神經運動傳導速度越快。體內累積砷劑量越高者，其尺神經運動傳導、感覺傳導、脛神經運動傳導及腓腸神經感覺傳導速度越慢。營養素的攝取和神經傳導速度的相關性並不穩定。MTHFR基因多形性和神經傳導速度也沒有發現一致的相關。

關鍵字

砷 ； 神經傳導 ； 甲烯基四氫葉酸還原酵素

並列摘要

The reduction of arsenic detoxification occurs mainly by methylation, which may compete with myelination and affect nerve conduction. In order to evaluate the association between nerve conduction velocity and arsenic exposure, and genetic polymorphisms of MTHFR, 130 junior high school students were selected. All of them were examed with the motor nerve conduction velocity on median nerve, ulnar nerve, peroneal nerve and tibia nerve, as well as the sensory nerve conduction velocities on median nerve, ulnar nerve and sural nerve. The concentration of arsenic in well water was obtained by matching the data with a cohort study performed in the same area in 1991. Other exposure data, for example, the years of drinking well water, the years of stop drinking well water, and the daily amount of drinking well water, were obtained from the questionnaires. Buccal mucosa were collected from each subject and genotyped for MTHFR by PCR-RFLP methods. The allele frequency of thymine in this study group was 0.27. After adjusting the data with sex and height, motor nerve conduction velocities in median nerve and ulnar nerve in subjects with fewer years of stop drinking well water were significantly slower than the velocities in the others. Motor nerve conduction velocities in ulnar nerve and tibia nerve, as well as sensory nerve conduction velocity in ulnar nerve and sural nerve in subjects with higher amount of cumulative arsenic were significantly slower than the velocities in the others. The correlation between the intake of some vitamins and nerve conduction velocity is not obvious. Neither did the polymorphism of MTHFR affect the nerve conduction velocity.

並列關鍵字

arsenic ； nerve conduction ； methylenetetrahydrofolate reductase (MTHFR)

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