van Pelt A M, van den Brink C E, de Rooij D G, van der Saag P T
Department of Cell Biology, Medical School, State University of Utrecht, The Netherlands.
Endocrinology. 1992 Jul;131(1):344-40. doi: 10.1210/endo.131.1.1319320.
Recently, we have reported that retinoic acid (RA), similarly to retinol acetate, is able to reinitiate spermatogenesis in vitamin A-deficient rats. Here, we investigated the expression of RA receptors RAR alpha, RAR beta, RAR gamma, and retinoid X receptor RXR alpha by Northern blot analysis of poly(A)+ RNA of testes of vitamin A-deficient rats before and after reinitiation of spermatogenesis induced by injection of retinol acetate or RA and testes of 21-day-old and 10-week-old normal rats. In the testis of vitamin A-deficient rats 1.9-, 2.8-, and 3.8-kilobase (kb) transcripts of RAR alpha; 2.8- and 3.3-kb transcripts of RAR beta; 1.8-, 2.8-, and 3.4-kb transcripts of RAR gamma; and two transcripts of RXR alpha of 2.5 and 4.8 kb are expressed. When vitamin A-deficient rats receive RA or retinol acetate, a 3-fold increase in the amount of poly(A)+ RNA per testis can be observed after 8 h, while the amounts of glyceraldehyde-3-phosphate dehydrogenase and sulfated glycoprotein-1 mRNA hardly change. Also, the expression of several transcripts of each RAR type is significantly increased from 1.8- up to 3.6-fold. Moreover, additional transcripts of RAR beta and RXR alpha (1.8 and 1.0 kb, respectively) can be detected. In the testes of 21-day-old rats, three transcripts of each RAR type and two RXR alpha transcripts are expressed. In contrast, in the normal adult rat testis the expression of all RARs, if present, is lower than that in the 21-day-old rat testis or the adult vitamin A-deficient rat testis. The expression of all transcripts of each RAR in the testis of 21-day-old rats shows great similarity with the expression in the testis of the vitamin A-deficient rat after replacement of retinol acetate or RA. These changes in expression indicate that RARs and RXR alpha may play a role in the process of proliferation and differentiation of A spermatogonia, which is induced in vitamin A-deficient rats shortly after replacement of RA or retinol acetate.
最近，我们报道了视黄酸（RA）与醋酸视黄醇类似，能够使维生素A缺乏的大鼠重新启动精子发生过程。在此，我们通过Northern印迹分析，检测了维生素A缺乏的大鼠在注射醋酸视黄醇或RA诱导精子发生重新启动前后，以及21日龄和10周龄正常大鼠睾丸的poly(A)+ RNA中RA受体RARα、RARβ、RARγ和类视黄醇X受体RXRα的表达情况。在维生素A缺乏的大鼠睾丸中，表达有1.9 kb、2.8 kb和3.8 kb的RARα转录本；2.8 kb和3.3 kb的RARβ转录本；1.8 kb、2.8 kb和3.4 kb的RARγ转录本；以及2.5 kb和4.8 kb的两种RXRα转录本。当维生素A缺乏的大鼠接受RA或醋酸视黄醇后，8小时后每个睾丸中poly(A)+ RNA的量可增加3倍，而甘油醛-3-磷酸脱氢酶和硫酸化糖蛋白-1 mRNA的量几乎没有变化。此外，每种RAR类型的几种转录本的表达均显著增加1.8至3.6倍。而且，还能检测到RARβ和RXRα的额外转录本（分别为1.8 kb和1.0 kb）。在21日龄大鼠的睾丸中，每种RAR类型有三种转录本以及两种RXRα转录本表达。相比之下，在正常成年大鼠睾丸中，所有RAR（如果存在）的表达低于21日龄大鼠睾丸或成年维生素A缺乏大鼠睾丸中的表达。21日龄大鼠睾丸中每种RAR的所有转录本的表达与维生素A缺乏大鼠在给予醋酸视黄醇或RA后睾丸中的表达表现出极大的相似性。这些表达变化表明，RAR和RXRα可能在维生素A缺乏的大鼠补充RA或醋酸视黄醇后不久诱导的A型精原细胞增殖和分化过程中发挥作用。
