用FDOPA 正子攝影來研究芳香族胺基酸AADC酵素缺乏症

Aromatic L-Amino Acid Decarboxylase deficiency studied with [18F]fluorodopa PET

張通銘(Tung-Ming Chang)

指導教授 ： 鄭瑞棠

長榮大學/健康科學學院/醫學研究所/碩士(2009年)

https://doi.org/10.6833/CJCU.2009.00116

摘要

Aromatic L-Amino Acid Decarboxylase (AADC) 屬於芳香族胺基酸代謝程中，負責轉換L-多巴(L-Dopa)成為多巴胺(dopamine)，及色氨基酸(Tryptophan)成為血清素(serotonin)的酵素。AADC酵素缺乏，將造成身體多巴胺與血清素缺乏，造成嚴重的發展遲緩、眼動危象(oculogyric crises,OGC)以及自律神經系統功能失調(autonomic dysfunction)。目前對於此病症的臨床表徵及診斷是清楚了解的，然而對此病症所造成的神經學異常，其致病機轉則尚未證實。
我們收集6位AADC酵素缺乏症病童，及5位非AADC酵素缺乏症兒童當成對照組，利用腦部FDOPA正子攝影來比較位在基底核尾核(caudate)，及蒼白核(putamen)上FDOPA的代謝變化。結果發現病童尾核FDOPA代謝比值(SOR)只有對照組的51%(P<0.005)，蒼白核只有54%(P<0.005)。
由上述結果可知，AADC缺乏症之病童，其突觸前黑質紋狀體多巴胺徑路(presynaptic nigrostriatal dopaminergic) 是低功能的(hypofunction)，因此造成腦脊髓液中的神經傳遞物質(neurotransmitter) 濃度下降並導致相關的神經學症狀。本研究更進一步可佐證FDOPA正子攝影可用來評估AADC酵素缺乏症病童其腦部多巴胺(Dopamine)異常代謝情況。

關鍵字

AADC酵素缺乏症 ； 正子攝影 ； 芳香族胺基酸

並列摘要

Objective: Although the symptomatology of aromatic L-Amino acid decarboxylase (AADC) deficiency has been well documented, the cerebral pathogenesis of this disorder is still unknown.
Methods: We used [18F]fluorodopa (FDOPA) PET to compare the presynaptic dopamine synthesis capacity in the striatum of six AADC deficient children and five non-AADC deficient children. Caudate and putamen FDOPA PET uptake values were measured and expressed as striatal-to-occipital ratio (SOR) and ratio R defined as SOR-1.
Results:
A conventional region of interest (ROI) analysis revealed that FDOPA uptake (SOR) in the caudate and putamen was significantly lower in the AADC deficient group than in the control group. The mean SOR of FDOPA uptake value in the caudate nucleus was 51% (p<0.005) and in the putamen 54% (p<0.005) of the control mean values.( 20% and 19% for ratio R, respectively )
Conclusions:
We confirm the presynaptic nigrostriatal dopaminergic hypofunction in AADC deficient children which results in lower levels of biogenic amine neurotransmitters and associated neurological symptoms. This work further has demonstrated that FDOPA PET may serve as a method to investigate the cerebral dopaminergic abnormality in AADC deficient children.

並列關鍵字

AADC deficiency ； FDOPA PET

參考文獻

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