Effects of Thyroidectomy and Triiodothyronine Administration on Rat Liver Alcohol Dehydrogenase
Effects of Thyroidectomy and Triiodothyronine Administration on Rat Liver Alcohol Dehydrogenase
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甲状腺切除联合三碘甲状腺原氨酸对大鼠肝脏乙醇脱氢酶的影响
DOI：
10.1016/0016-5085(81)90020-2
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发表时间：
1981
期刊：
影响因子：
29.4
通讯作者：
J. Potter
中科院分区：
文献类型：
--
作者：
E. Mezey;J. Potter
测定了大鼠甲状腺切除术对肝脏乙醇脱氢酶活性和乙醇消除率的影响。甲状腺切除术导致肝脏乙醇脱氢酶活性显着增加。通过淀粉凝胶电泳在甲状腺切除动物中证实了乙醇脱氢酶活性的三种同工酶，而与假手术对照动物中的两种同工酶相比。施用三碘甲状腺原氨酸降低了对照动物中的酶活性，并抑制了甲状腺切除动物中增强的活性。在对照动物和甲状腺切除动物中，体外三碘甲状腺原氨酸对乙醇脱氢酶的抑制作用与 NAD+ 具有竞争性，而与乙醇则没有竞争性。甲状腺切除术不会导致乙醇消除率发生任何变化。在对照组和甲状腺切除动物中，给予乙醇后胞质游离NAD+/NADH比值均下降，而线粒体游离NAD+/NADH比值仅在对照动物中下降。这些结果表明甲状腺是肝脏乙醇脱氢酶活性的抑制剂。还原当量从细胞质到线粒体的转移缺陷似乎限制了肝脏乙醇脱氢酶活性增加的甲状腺切除动物的乙醇消除速率。
The effect of thyroidectomy on the activity of liver alcohol dehydrogenase and on the rate of ethanol elimination was determined in the rat. Thyroidectomy resulted in a marked increase in liver alcohol dehydrogenase activity. Three isoenzymes of alcohol dehydrogenase activity were demonstrated in thyroidectomized animals by starch gel electrophoresis, as compared with two in sham-operated control animals. Triiodothyronine administration decreased the enzyme activity in control animals, and suppressed the enhanced activity in thyroidectomized animals. Inhibition of alcohol dehydrogenase by triiodothyronine in vitro was found to be competitive with respect to NAD+and uncompetitive with respect to ethanol in both control and thyroidectomized animals. Thyroidectomy did not result in any changes in the rate of ethanol elimination. The cytosolic free NAD+/NADH ratio decreased after ethanol administration in both control and thyroidectomized animals, while the mitochondrial-free NAD+/NADH ratio decreased only in the control animals. These results indicate that the thyroid is a repressor of liver alcohol dehydrogenase activity. A defect in the transfer of reducing equivalents from the cytosol to the mitochondria appears to limit the rate of ethanol elimination in thyroidectomized animals with increased liver alcohol dehydrogenase activity.