Effect of acetylcholine on the activity of dopamine β‐hydroxylase in rat brain
Effect of acetylcholine on the activity of dopamine β‐hydroxylase in rat brain
复制标题
乙酰胆碱对大鼠脑内多巴胺β-羟化酶活性的影响
DOI：
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发表时间：
1976
期刊：
影响因子：
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通讯作者：
P. Ozand
中科院分区：
文献类型：
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作者：
A. M. Karahasanoglu;E. Edwards;J. Tildon;P. Ozand
发现大鼠脑中60%的多巴胺β-羟化酶（DBH）（EC 1.14.2.1）活性与膜组分结合。Triton X-100的添加完全溶解DBH，并允许估计总酶活性。在不存在Triton X-100的情况下，在匀浆中可以检测到DBH，但其为总酶活性的30-45%;在粗突触体组分中，该值仅为10%。在含有2 × 10 ~（-3）M乙酰胆碱（ACh）的培养基中孵育脑片，在不加洗涤剂的情况下测得的DBH活性增加2 ~ 2.5倍，但总酶活性保持不变。加入6 × 10-2 M K+代替ACh也产生类似的效果，但在不加去污剂的情况下，DBH活性的增加仅为25%。ACh的作用可以通过将其从培养基中移除或通过加入二乙基对硝基苯磷酸盐（对氧磷）4 × 10-5 M来逆转。加入4 × 10 ~（-4）M雌二醇可增强ACh的作用。醋酸盐和胆碱都没有任何效果。完整的细胞边界似乎是必要的，因为除了乙酰胆碱后完全均质化引起的活动没有增加。ACh引起膜结合DBH的比活性增加（9-10）倍，但胞质溶胶中酶的比活性没有变化。虽然ACh的作用类似于Triton X-100的作用，但这不是由于DBH的增溶作用。乙酰胆碱的存在并没有增加释放到培养介质中的DBH。
Sixty percent of the dopamine β‐hydroxylase (DBH) (EC 1.14.2.1) activity in rat brain was found to be bound to membrane fractions. The additions of Triton X‐100 solubilized DBH completely and permitted the estimated of the total enzyme activity. In homogenates the DBH could be detected in the absence of Triton X‐100 but was 30–45% of this total enzyme activity; in crude synaptosomal fractions this value was only 10%. Incubation of brain slices in media containing 2 × 10–3M acetylcholine (ACh) led to an increase by a factor of 2–2.5 in the activity of DBH measured in the absence of detergents; however, total enzyme activity remained the same. The addition of 6 × 10–2 M K+ in place of ACh produced a similar effect; however, the increase in the activity of DBH measured in the absence of detergents was only 25%. The effect of ACh could be reversed by removing it from the medium, or by the addition of diethyl p‐nitrophenyl phosphate (paraoxon) 4 × 10–5 M. The addition of eserine 4 × 10–4 M increased the effect of ACh at 15 min of incubation. Neither acetate nor choline had any effect. Intact cell boundaries appeared to be necessary, since addition of ACh after complete homogenization caused no increase in activity. ACh caused a (9–10)‐fold increase in the specific activity of membrane‐bound DBH but no change in the specific activity of the enzyme in cytosol. Although the effect of ACh mimicked the effect of Triton X‐100, it was not due to the solubilization of DBH. The presence of ACh did not increase the release of DBH into the incubation medium.