Trudel C, Couët J, Martel C, Labrie C, Labrie F
Medical Research Council Group in Molecular Endocrinology, CHUL Research Center, Ste-Foy, Quebec, Canada.
Endocrinology. 1991 Oct;129(4):2077-84. doi: 10.1210/endo-129-4-2077.
This study describes the regulation of adrenal 3 beta-hydroxy-5-ene-steroid dehydrogenase/delta 5-delta 4-isomerase (3 beta HSD) expression and activity by ACTH and corticosterone, alone or in combination, in intact male and female rats as well as the effect of ACTH on 3 beta HSD expression and activity in the adrenals of hypophysectomized female animals. The effect of treatment on total 3 beta HSD mRNA levels was measured by dot blot hybridization using rat 3 beta HSD cDNA, while the specific regulation of type I and type II 3 beta HSD mRNAs was analyzed by ribonuclease protection assay. The concentration of 3 beta HSD protein was measured by Western blot, using cross-reacting antibodies raised against purified human placental 3 beta HSD, while 3 beta HSD enzymatic activity was measured by the conversion of [14C]dehydroepiandrosterone into [14C]androstenedione. The present data show that the trophic effect of ACTH on male and female rat adrenals is accompanied by increases in total 3 beta HSD mRNA, enzymatic activity, and protein content. Hypophysectomy, on the other hand, causes a marked decrease in 3 beta HSD mRNA levels and enzymatic activity, which is completely reversed by administration of ACTH. On the other hand, corticosterone treatment results in a marked inhibition of 3 beta HSD mRNA levels, enzymatic activity, and protein content in intact animals; this effect is probably mediated by a decrease in ACTH secretion. The present data show that ACTH and corticosterone, via its inhibitory action on ACTH secretion, have potent and opposite effects on the expression of two 3 beta HSD genes in the rat adrenal; a parallel effect is observed on both type I and II 3 beta HSD. Such data suggest that 3 beta HSD could well play a major role in the regulation of steroid formation in the adrenal cortex.
本研究描述了促肾上腺皮质激素（ACTH）和皮质酮单独或联合作用对完整雄性和雌性大鼠肾上腺3β-羟基-5-烯-类固醇脱氢酶/δ5-δ4-异构酶（3βHSD）表达及活性的调节，以及ACTH对垂体切除雌性动物肾上腺中3βHSD表达和活性的影响。采用大鼠3βHSD cDNA通过斑点印迹杂交法测定处理对总3βHSD mRNA水平的影响，同时通过核糖核酸酶保护试验分析Ⅰ型和Ⅱ型3βHSD mRNA的特异性调节。使用针对纯化的人胎盘3βHSD产生的交叉反应抗体通过蛋白质印迹法测定3βHSD蛋白的浓度，而通过将[14C]脱氢表雄酮转化为[14C]雄烯二酮来测定3βHSD酶活性。目前的数据表明，ACTH对雄性和雌性大鼠肾上腺的营养作用伴随着总3βHSD mRNA、酶活性和蛋白质含量的增加。另一方面，垂体切除导致3βHSD mRNA水平和酶活性显著降低，而ACTH给药可使其完全逆转。另一方面，皮质酮处理导致完整动物中3βHSD mRNA水平、酶活性和蛋白质含量显著抑制；这种作用可能是由ACTH分泌减少介导的。目前的数据表明，ACTH和皮质酮通过其对ACTH分泌的抑制作用，对大鼠肾上腺中两个3βHSD基因的表达具有强大且相反的作用；在Ⅰ型和Ⅱ型3βHSD上均观察到类似作用。这些数据表明，3βHSD很可能在肾上腺皮质类固醇生成的调节中起主要作用。
