Effects of insulin on phenylketonuria Part 1. Effects on catecholamine metabolism

1. PKU患者6名と対照正常人8名にインスリンを投与して,血中フェニールアラニン,チロシンおよびカテコールアミン代謝について検討した. 2. インスリン投与によってPKU患者の血中フェニールアラニン値は症例毎に著しい変動を示し,血中フェニールアラニン値の低下する例が認められる反面,増加する例も認められた. 3. PKU患者にインスリンを投与すると,血中カテコールアミン値に増加傾向が認められた.チラミン,オクトパミンは60分後に著明な増加を示す例が多くみられた. 4. PKU患者のうち,インスリン投与によって,フェニールアラニン代謝およびカテコールアミン代謝の改善が認められた症例については,今後適当な方法を開発することにより,治療効果が期待される.Six PKU subjects and eight normal subjects were examined for serum levels of catecholamine, tyramine, octopamine and phenylalanine prior to and 60 minutes, 120 minutes and 24 hours after a single muscular injection of insulin. Catecholamine was determined by gaschromatographic method (Electron capture detector). The serum level of dopamine, norepinephrine and epinephline increased 120 minutes after the insulin injection. Tyramine and octopamine increased remarkably 60 minutes after insulin injection. The serum levels of phenylalanine of each PKU subject were fairly variable. Homovanillic acid in urine samples obtained from PKU subjects was quantified using fluorometric method. The one sample was collected for 24 hours prior to the insulin injection. The other urine sample was collected following the insulin injection. Urine homovanillic acid of 4 PKU subjects were increased, but it was decreased in two other subjects after insulin injection. These findings suggest that insulin injection to the PKU subjects may increase a side pathway of catecholamine metabolism from tyrosine to tyramine, or to octopamine via tyramine. Insulin may act as an activator of some metabolic enzyme for catecholamine metabolism in PKU subjects