Braham J, Sarova-Pinhas I, Crispin M, Golan R, Levin N, Szeinberg A
Br Med J. 1969 May 31;2(5656):552-5. doi: 10.1136/bmj.2.5656.552.
Reduction of dopamine concentrations in the brains of patients with Parkinsonism, together with reported clinical improvement after the administration of dihydroxyphenylalanine, has led to the hypothesis that impaired hydroxylation of tyrosine may be associated with the disease. To test this hypothesis oral loading tests with L-phenylalanine and tyrosine were carried out in patients and controls. After phenylalanine lower blood levels of this were found in Parkinsonian patients than in controls, but tyrosine levels were the same. After tyrosine lower levels of this were also found in patients compared with controls. It is suggested that these findings indicate a decreased rate of tyrosine utilization in Parkinson's disease together with intestinal malabsorption; the latter is supported by the finding of abnormal D-xylose tolerance in these patients.
帕金森病患者大脑中多巴胺浓度降低，以及服用二羟基苯丙氨酸后临床症状有所改善，这引发了一种假说，即酪氨酸羟化受损可能与该疾病有关。为了验证这一假说，对患者和对照组进行了L-苯丙氨酸和酪氨酸的口服负荷试验。服用苯丙氨酸后，帕金森病患者体内该物质的血药浓度低于对照组，但酪氨酸水平相同。服用酪氨酸后，患者体内该物质的水平也低于对照组。这些发现表明，帕金森病患者酪氨酸利用率降低，同时伴有肠道吸收不良；这些患者异常的D-木糖耐受性这一发现支持了后者。
