Estrogen controls branched-chain amino acid catabolism in female rats.
Estrogen controls branched-chain amino acid catabolism in female rats.
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DOI：
10.1093/jn/134.10.2628
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发表时间：
2004-10
期刊：
影响因子：
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通讯作者：
M. Obayashi;Y. Shimomura;N. Nakai;N. Jeoung;M. Nagasaki;T. Murakami;Yuzo Sato;Robert A. Harris
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文献类型：
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作者：
M. Obayashi;Y. Shimomura;N. Nakai;N. Jeoung;M. Nagasaki;T. Murakami;Yuzo Sato;Robert A. Harris
雌性大鼠的分支链α-酮酸脱氢酶复合体(BCKDC)的活性状态存在昼夜节律，而雄性大鼠则不存在。我们试图确定卵巢激素在这种酶调节差异中所起的作用。一系列实验检测了4天发情周期、卵巢切除和女性性激素替代对支链氨基酸分解代谢的影响。该复合体活性状态的前期降低对应于血浆17β-雌二醇水平的升高。去势停用性腺激素后，BCKDC活性状态增加，支链α-酮酸脱氢酶(BDK)活性降低。然而，17β-雌二醇逆转了这些效应，导致BDK活性增加，从而降低了复合体的活性。黄体酮给药无效。17β-雌二醇停用和替代引起的活性BCKDC百分比的变化是由于与该复合体相关的BDK蛋白的量的变化，从而导致其活性的变化。因此，雌性大鼠BCKDC活性状态的显著日变化涉及BDK活性的雌激素调控。我们推测，17β-雌二醇控制的喂养模式产生了BCKDC活性的这些变化。这可能在雌性大鼠身上起到了保存蛋白质合成所需氨基酸的作用。
A diurnal rhythm occurs in the activity state of branched-chain alpha-keto acid dehydrogenase complex (BCKDC) in female but not male rats. We attempted to determine the role played by ovarian hormones in this difference in enzyme regulation. A series of experiments examined the effects of the 4-d estrous cycle, ovariectomy, and replacement of female sex steroids on the catabolism of BCAAs. A proestrous decrease in the activity state of the complex corresponded to an increase in the plasma 17beta-estradiol level. Withdrawal of gonadal steroids by ovariectomy resulted in an increase in the activity state of BCKDC and a decrease in the activity of the branched-chain alpha-keto acid dehydrogenase kinase (BDK). However, 17beta-estradiol reversed these effects, resulting in an increase in the BDK activity, thereby decreasing the activity of the complex. Progesterone administration was ineffective. The changes in the percentage of active BCKDC caused by 17beta-estradiol withdrawal and replacement resulted from changes in the amount of BDK protein associated with the complex and therefore its activity. Thus, the marked diurnal variation in the activity state of BCKDC exhibited by female rats involves estrogenic control of BDK activity. We hypothesize that the 17beta-estradiol-controlled feeding pattern produces these variations in BCKDC activity. This may function in female rats to conserve essential amino acids for protein synthesis.