大鼠间质细胞中11β-羟类固醇脱氢酶mRNA的表达

Expression of 11β-hydroxysteroid dehydrogenase mRNA in rat Leydig cells

间质细胞中１１β－羟类固醇脱氢酶（１１β－ＨＳＤ）通过控制细胞内糖皮质激素（大鼠体内是皮质酮）浓度调节睾酮合成。大鼠出生后２６天内，其未成熟间质细胞不含１１β－ＨＳＤ，随着间质细胞成熟，１１β－ＨＳＤ逐渐产生，成年大鼠间质细胞中１１β－ＨＳＤ活性最高。１１β－ＨＳＤ控制着间质细胞中糖皮质激素浓度，生理浓度糖皮质激素同样调节着１１β－ＨＳＤ活性水平。本研究观察了三个不同年龄组大鼠和切除肾上腺后及切除后补充皮质酮大鼠，间质细胞中１１β－ＨＳＤｍＲＮＡ表达情况，发现：出生２１天大鼠间质细胞中无１１β－ＨＳＤｍＲＮＡ的表达，４５天大鼠有１１β－ＨＳＤｍＲＮＡ表达，９０天大鼠表达量最大，切除肾上腺后大鼠间质细胞中１１β－ＨＳＤｍＲＮＡ表达降低，切除后经皮质酮补充大鼠１１β－ＨＳＤｍＲＮＡ表达量回复到对照组水平。结果表明三个不同年龄组大鼠间质细胞中１１β－ＨＳＤｍＲＮＡ表达情况和以往采用免疫组织化学及生物化学方法测定抗原含量或酶活性的结果是一致的。

11β-Hydroxysteroid dehydrogenase (11β-HSD) in Leydig cells regulate steroidogenesis by controlling intracellular glucocorticoid (corticosterone, B, in rat) concentration. Prior to the 26 th postnatal day, 11β-HSD is absent from rat immature Leydig cells. Subsequently, the enzyme is produced as the Leydig cells are being matured. The highest levels of 11β-HSD activity are presented in adult Leydig cells. 11β-HSD controls the intracellular glucocorticoids concentration in Leydig cells and the glucocorticoids at the physiological levels also regulate levels of 11β-HSD activity in Leydig cells. The expression of 11β-HSD mRNA in Leydig cells from three different age of rats, and adrenalectomized rats, with and without B replacement was observed in this study. The steady state levels of 11β-HSD mRNA could not be detected in Leydig cells from 21 days of age of immature rats, but this can be measured in 45 days of age of rats. The highest level of expression of 11β-HSD mRNA was found in adult Leydig cells. The mRNA expression of 11β-HSD was declined in Leydig cells after adrenalectomy, and this decline was prevented by B replacement. The result indicates that 11β-HSD mRNA levels expressed in three different age of rats are parallel with that of antigen of immunohistochemical analysis and with that of enzyme activity of biochemical measurement in previous study. Similarly, the effect of B at physiological and endogenous levels on the expression of 11β-HSD mRNA corresponds to that on enzyme activity.