Viger R S, Robaire B
Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada.
J Androl. 1995 Mar-Apr;16(2):108-17.
The mammalian epididymis is the site where spermatozoa are matured and then stored. Though many studies have described epididymal functions and their regulation, little is known about how aging affects this tissue. The Brown Norway rat, which does not show the many age-related pathologies common to other rat strains, was used as a model to study aging of the epididymis. The present study was designed to determine the effect of aging on the mRNA levels for selected markers of epididymal function. Brown Norway rats ranging in age from 6 to 30 months were examined at 6-month intervals; epididymides were sectioned into caput-corpus and cauda regions. Relative mRNA concentrations were assessed using Northern blot analysis and specific cDNAs for the rat 5 alpha-reductase isozymes, types 1 and 2; proenkephalin; the androgen receptor; epididymal proteins B/C and D/E; and sulfated glycoprotein-2 (SGP-2, clusterin). Northern blots were quantitated by densitometric scanning. In the caput-corpus epididymidis, 5 alpha-reductase type 1 and type 2 mRNA levels decreased significantly by 43% and 33%, respectively, between 6 and 12 months and by 64% and 40%, respectively, between 6 and 30 months. No significant change, however, was found in the expression of the 5 alpha-reductase mRNAs in the cauda epididymidis. Interestingly, proenkephalin mRNA was only detected in the caput-corpus epididymidis of 6-month-old rats. In marked contrast to the 5 alpha-reductase isozymes and proenkephalin, no significant age-related changes were observed in the mRNA levels for the androgen receptor, protein B/C, or protein D/E. No age-related changes in mRNA expression for SGP-2 occurred in the caput-corpus epididymidis. However, in the cauda epididymidis, SGP-2 mRNA levels rose by twofold between 6 and 18 months and then decreased sharply by 75% between 18 and 30 months. We conclude that as the epididymis ages, the expression of genes for certain specific markers of epididymal function is affected in a region-specific manner. Further, the decrease in the concentrations of the mRNAs for the 5 alpha-reductase isozymes and proenkephalin in the epididymis between 6 and 12 months is thus far the earliest marker for aging in the male reproductive tract of the Brown Norway rat.
哺乳动物的附睾是精子成熟并储存的部位。尽管许多研究描述了附睾的功能及其调节，但对于衰老如何影响该组织却知之甚少。不表现出其他大鼠品系常见的许多与年龄相关病理特征的棕色挪威大鼠被用作研究附睾衰老的模型。本研究旨在确定衰老对附睾功能选定标志物mRNA水平的影响。对年龄在6至30个月的棕色挪威大鼠每隔6个月进行一次检查；将附睾切成头体部和尾部区域。使用Northern印迹分析和大鼠5α-还原酶同工酶1型和2型、脑啡肽原、雄激素受体、附睾蛋白B/C和D/E以及硫酸化糖蛋白-2（SGP-2，簇集蛋白）的特异性cDNA评估相对mRNA浓度。通过密度扫描对Northern印迹进行定量。在附睾头体部，6至12个月期间，5α-还原酶1型和2型mRNA水平分别显著下降43%和33%，6至30个月期间分别下降64%和40%。然而，在附睾尾部，5α-还原酶mRNA的表达未发现显著变化。有趣的是，脑啡肽原mRNA仅在6月龄大鼠的附睾头体部检测到。与5α-还原酶同工酶和脑啡肽原形成鲜明对比的是，雄激素受体、蛋白B/C或蛋白D/E的mRNA水平未观察到与年龄相关的显著变化。附睾头体部SGP-2的mRNA表达未出现与年龄相关的变化。然而，在附睾尾部，SGP-2 mRNA水平在6至18个月期间上升了两倍，然后在18至30个月期间急剧下降了75%。我们得出结论，随着附睾衰老，附睾功能某些特定标志物的基因表达以区域特异性方式受到影响。此外，6至12个月期间附睾中5α-还原酶同工酶和脑啡肽原mRNA浓度的降低是迄今为止棕色挪威大鼠雄性生殖道衰老的最早标志物。
