Zhuang Y H, Bläuer M, Ylikomi T, Tuohimaa P
Department of Anatomy, Tampere University Medical School, Finland.
J Steroid Biochem Mol Biol. 1997 Jan;60(1-2):67-76. doi: 10.1016/s0960-0760(96)00163-x.
In order to understand the mechanisms of retinol action on the testis, testicular retinoic acid receptor alpha, beta(RAR alpha and beta), androgen receptor (AR) and inhibin alpha-subunit were studied in normal, vitamin A-deficient (VAD) and vitamin A-supplemented rats by immunohistochemistry and immunoblotting. Compared to the normal testis, expression of 110 K AR was up-regulated by vitamin A withdrawal, whereas 51 K RAR alpha remained unchanged. An additional 55 K RAR alpha signal was observed. Readministration of retinol caused a marked decrease of AR in the VAD testis. By 24 h, AR declined to below the normal level. Although the 51 K RAR alpha signal remained unchanged, the 55 K band was slightly up-regulated at 6 h after retinol administration. A 51 K RAR beta protein was seen in the VAD but in not the normal testis. The intensity of the 51 K RAR beta band remained constant before and after the administration of retinol, but it had a slight up-shift at 6 h after retinol injection, suggesting post-translational modification of the receptor. The inhibin alpha-subunit of 18 K protein was undetectable in the VAD testis and increased to above normal level at 24 h after retinol administration. Immunohistochemically, nuclear AR immunostaining was more intense in the VAD testis than in the normal testis. The intensity of immunostaining declined in all AR-positive cells after the injection of retinol, but the decrease was more evident in Sertoli than in other cells. At 24 h after retinol the immunostaining was undetectable in most Sertoli cells. The regulation of the inhibin alpha-subunit by retinol in the cytoplasm of Sertoli cells detected by immunohistochemistry was correlated to the results in immunoblotting. These results suggest a possible interplay between retinoids, androgen and inhibin signalling systems in Sertoli cells in the regulation of spermatogenesis during retinol action.
为了解视黄醇对睾丸的作用机制，采用免疫组织化学和免疫印迹法，对正常、维生素A缺乏（VAD）和补充维生素A的大鼠睾丸中的视黄酸受体α、β（RARα和β）、雄激素受体（AR）和抑制素α亚基进行了研究。与正常睾丸相比，维生素A缺乏时110K AR的表达上调，而51K RARα保持不变。观察到另外一个55K RARα信号。重新给予视黄醇后，VAD睾丸中的AR显著减少。到24小时时，AR降至正常水平以下。虽然51K RARα信号保持不变，但视黄醇给药后6小时，55K条带略有上调。在VAD睾丸中可见51K RARβ蛋白，而正常睾丸中未见。视黄醇给药前后，51K RARβ条带的强度保持恒定，但在视黄醇注射后6小时有轻微上移，提示该受体存在翻译后修饰。18K蛋白的抑制素α亚基在VAD睾丸中未检测到，视黄醇给药后24小时增加至正常水平以上。免疫组织化学显示，VAD睾丸中核AR免疫染色比正常睾丸更强。注射视黄醇后，所有AR阳性细胞的免疫染色强度均下降，但支持细胞中的下降比其他细胞更明显。视黄醇注射后24小时，大多数支持细胞中免疫染色无法检测到。免疫组织化学检测到视黄醇对支持细胞胞质中抑制素α亚基的调节与免疫印迹结果相关。这些结果表明，在视黄醇作用过程中，类视黄醇、雄激素和抑制素信号系统在支持细胞中调节精子发生可能存在相互作用。
