Viger R S, Robaire B
Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada.
Endocrinology. 1992 Sep;131(3):1534-40. doi: 10.1210/endo.131.3.1505481.
The regulation of epididymal 5 alpha-reductase mRNA is multifactorial and segment-specific. To further investigate the regulation of the message for the enzyme, the expression of 5 alpha-reductase mRNA in the rat epididymis was studied as a function of postnatal development. Developmental changes in 5 alpha-reductase mRNA concentrations were assessed by probing Northern blots with the full-length cDNA for rat steroid 5 alpha-reductase. In the first experiment the effect of postnatal age on 5 alpha-reductase mRNA concentrations in the caput-corpus and cauda epididymides was studied. Male rats, taken at 1-week intervals between the ages of 7-91 days, were used. In both epididymal regions, the mRNA for 5 alpha-reductase was present at all ages examined; it appeared in the immature animal at least 2 weeks before detectable 5 alpha-reductase enzyme activity. In the caput-corpus epididymidis, mRNA levels for 5 alpha-reductase decreased by half between postnatal days 7 and 21, rose 5-fold by day 56, and then remained constant through day 91. No change with postnatal age, however, was observed in the cauda epididymidis. In the second experiment, the longitudinal distribution of 5 alpha-reductase mRNA on postnatal days 21, 42, 49, 56, 77, and 91 was studied. The mRNA levels for 5 alpha-reductase increased remarkably, by 6- to 7-fold, in the initial segment of the caput epididymidis between postnatal days 21 and 42 and stayed constant thereafter. However, no significant change comparable to that found in the initial segment was observed in the adjacent proximal caput region or in any of the other epididymal segments. Thus, the 5-fold rise in 5 alpha-reductase mRNA concentrations that occurred in the caput-corpus epididymidis in the first experiment can be attributed solely to changes in the initial segment. We conclude that steady state concentrations of epididymal 5 alpha-reductase mRNA vary dramatically at different postnatal ages and are highly specific with respect to epididymal segment.
附睾5α-还原酶mRNA的调节是多因素的且具有节段特异性。为了进一步研究该酶的信使核糖核酸（mRNA）的调节机制，我们研究了大鼠附睾中5α-还原酶mRNA的表达随出生后发育的变化情况。通过用大鼠类固醇5α-还原酶的全长互补DNA（cDNA）探测Northern印迹来评估5α-还原酶mRNA浓度的发育变化。在第一个实验中，研究了出生后年龄对附睾头体部和尾部5α-还原酶mRNA浓度的影响。使用的雄性大鼠年龄在7至91天之间，每隔1周取一次样。在两个附睾区域，在所检查的所有年龄段都存在5α-还原酶的mRNA；它在未成熟动物中出现的时间至少比可检测到的5α-还原酶活性早2周。在附睾头体部，5α-还原酶的mRNA水平在出生后第7天至21天之间下降了一半，到第56天上升了5倍，然后在第91天之前保持恒定。然而，在附睾尾部未观察到随出生后年龄的变化。在第二个实验中，研究了出生后第21天、42天、49天、56天、77天和91天5α-还原酶mRNA的纵向分布。在出生后第21天至42天之间，附睾头起始段的5α-还原酶mRNA水平显著增加了6至7倍，此后保持恒定。然而，在相邻的近端附睾头区域或任何其他附睾节段中未观察到与起始段相当的显著变化。因此，在第一个实验中附睾头体部5α-还原酶mRNA浓度5倍的升高完全可归因于起始段的变化。我们得出结论，附睾5α-还原酶mRNA的稳态浓度在不同出生后年龄有显著变化，并且在附睾节段方面具有高度特异性。
