Inverse relationship between ovarian aromatase cytochrome P450 and 5 alpha-reductase enzyme activities and mRNA levels during the estrous cycle in the rat.
Inverse relationship between ovarian aromatase cytochrome P450 and 5 alpha-reductase enzyme activities and mRNA levels during the estrous cycle in the rat.
复制标题
大鼠动情周期中卵巢芳香酶细胞色素 P450 和 5α-还原酶活性与 mRNA 水平之间的负相关关系。
DOI：
10.1016/0960-0760(92)90255-h
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Simpson,ER
中科院分区：
文献类型：
--
作者：
Lephart,ED;Doody,KJ;McPhaul,MJ;Simpson,ER
在本研究中，我们检测了成年周期大鼠卵巢组织中芳香酶细胞色素P450(P450AROM)和5-α-还原酶的活性和基因水平的变化。在发情周期的每个阶段，用3H2O释放法(P450 AROM)和薄层层析法(5α-还原酶)测定酶活性。以~(32)P标记的大鼠α为探针，用Northern印迹法检测卵巢中P450-AROM和5-AROM还原酶基因的表达水平。用放射免疫法测定血清黄体生成素水平。在周期大鼠卵巢组织中检测到3种P450AROMmRNA(分别位于1.7、2.2和2.7kb)。在整个周期中，所有三种P450AROM的水平都是最高的。P450AROM在动情间期和动情前期最高，动情期下降，动情期几乎检测不到。相反，在周期动物的卵巢组织中检测到一种2.5kb的5-α-还原酶基因。卵巢5-α-还原酶在动情间期和动情前期表达最低，动情期表达增加，动情后期表达最丰富，与P450AROM的表达模式相反。P450AROM和5-α-还原酶活性的变化模式与各自的mRNA谱相似，但落后于mRNA谱约24小时，即发情周期的一个阶段。芳香酶活性在发情间期为1.5pmol/h/mg蛋白，发情前期增加3倍以上(≈为5.5pmol/h/mg蛋白)，发情期下降，发情后期降至最低值(≈1.0pmol/h/mg蛋白)。相反，5α-还原酶活性模式实质上是发情周期中P450AROM活性模式的镜像。5α-还原酶在发情前期(≈5pmol/h/mg蛋白)和发情期(≈8pmol/h/mg蛋白)水平最低，在发情后期增加3倍以上，而在发情间期最高(≈36pmol/h/mg蛋白)。P450AROM和5-α-还原酶基因水平及其各自的酶活性的正常化表明，在发情周期中，基因丰度与随后(24小时后)酶活性水平的升高之间存在对应关系。这些发现提示：(B)在大鼠发情周期中，P450AROM和5-α-还原酶在酶活性和基因表达方面存在相反的模式。
In the present study, we examined the changes in enzyme activity and mRNA levels of aromatase cytochrome P450 (P450AROM) and 5α-reductase in ovarian tissue from adult cyclic rats. For each stage of the estrous cycle, the enzymatic activities were quantified by means of the3H2O-release assay in the case of P450AROMand thin-layer chromatography in the case of 5α-reductase. Levels of mRNA encoding P450AROMand 5α-reductase in the ovary were determined by the Northern blot analysis utilizing32P-labeled rat cDNAs as probes. Serum LH levels were determined by RIA. Three P450AROMmRNA species were detected (at 1.7, 2.2 and 2.7 kb) in ovarian tissue from cyclic rats. All three P450AROMlevels were highest during in a co-ordinated fashion throughout the cycle. The P450AROMlevels were highest during diestrus and proestrus, decreased during estrus while at metestrus the levels were nearly nondetectable. Conversely, one 5α-reductase mRNA species at 2.5 kb was detected in ovarian tissue from cyclic animals. Ovarian 5α-reductase mRNA levels were lowest during diestrus and proestrus, increased at estrus and were most abundant during metestrus; a pattern opposite to that of P450AROM. The pattern of change in P450AROMand 5α-reductase activities paralleled that of the respective mRNA profiles but lagged behind the mRNA profiles by about 24 h, or one stage of the estrous cycle. Aromatase activity was 1.5 pmol/h/mg protein during diestrus, increased over 3-fold at proestrus (≈5.5 pmol/h/mg protein), decreased at estrus and declined to the lowest values at metestrus (≈1.0 pmol/h/mg protein). In contrast, the 5α-reductase activity pattern was essentially the mirror image of the P450AROMactivity pattern during the estrous cycle. 5α-Reductase levels were lowest during proestrus (≈5 pmol/h/mg protein) and estrus (≈8 pmol/h/mg protein), increased over 3-fold during metestrus, while the highest activity levels occurred during diestrus (≈36 pmol/h/mg protein). The normalization of the P450AROMand 5α-reductase mRNA levels and their respective enzyme activities revealed a correspondence between mRNA abundance and subsequent increases (24 h later) in enzyme activity levels during the estrous cycle. These findings suggest follows the changes in the levels of their respective mRNAs and (b) an inverse pattern exists between P450AROMand 5α-reductase in terms of both enzymatic activity and mRNA expression during the estrous cycle in rat.