Effects of ascorbic acid deficiency on adrenal mitochondrial hydroxylations in guinea pigs.
Effects of ascorbic acid deficiency on adrenal mitochondrial hydroxylations in guinea pigs.
复制标题
抗坏血酸缺乏对豚鼠肾上腺线粒体羟基化的影响。
DOI：
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发表时间：
1978
影响因子：
6.5
通讯作者：
K. Karlmar
中科院分区：
文献类型：
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作者：
I. Björkhem;A. Kallner;K. Karlmar
用线粒体和分离的细胞色素P-450组分，研究了抗坏血酸缺乏对豚鼠肾上腺胆固醇和脱氧皮质酮羟化的影响。并与ACTH长期治疗的疗效进行比较。晚期坏血组和ACTH治疗组大鼠肾上腺重量、细胞色素P-450总量、胆固醇侧链断裂活性、血浆皮质醇水平和尿液未结合皮质醇排泄均明显增加。总脱氧皮质酮的11β-羟化和18-羟化不被刺激或仅有少量刺激。研究表明，晚期坏疽的主要影响是由于ACTH，ACTH的水平显著升高，很可能是应激的结果。在持续食用2-4周或添加小剂量抗坏血酸的动物中，观察到的变化不能完全解释为ACTH对正常肾上腺的影响。虽然血浆ACTH和皮质醇水平仅有小幅升高，尿中未结合皮质醇的排泄未受影响，但肾上腺线粒体对外源性胆固醇羟化的总能力显著增加。结论：肾上腺中的抗坏血酸水平可能对将胆固醇转化为孕烯醇酮的能力有一定的重要性。然而，在中度抗坏血酸缺乏时，正常的反馈调节是完整的，血浆皮质醇水平保持在正常范围内。
The effect of ascorbic acid deficiency on adrenal hydroxylation of cholesterol and deoxycorticosterone in guinea pigs was studied by using mitochondria and isolated cytochrome P-450 fractions. The effects obtained were compared with the effects of long-term treatment with ACTH. Advanced scurvy as well as treatment with ACTH resulted in an increase in the weight of the adrenals, the total amount of cytochrome P-450, the cholesterol side-chain cleavage activity, the cortisol level in plasma, and the excretion of unconjugated cortisol in urine. Total 11beta- and 18-hydroxylation of deoxycorticosterone were not stimulated or were stimulated only to a small extent. It is suggested that the major effects observed in advanced scurvy are due to ACTH, the level of which was significantly increased, most probably as a consequence of the stress. In animals kept on a scorbutogenic diet for 2-4 weeks or, with a small dose of ascorbate added, for several weeks, changes were observed that could not be fully explained as effects of ACTH on normal adrenals. Although the plasma levels of ACTH and cortisol were increased only to a small extent and excretion of unconjugated cortisol in urine was unaffected, there was a significant increase in the total capacity of adrenal mitochondria to hydroxylate exogenous cholesterol. It is concluded that the level of ascorbate in the adrenals might be of some importance for the capacity to convert cholesterol into pregnenolone. The normal feed-back regulation is, however, intact in moderate ascorbate deficiency and the plasma level of cortisol is kept within normal limits.