Zhu Q, Meisinger J, Emanuele N V, Emanuele M A, LaPaglia N, Van Thiel D H
Department of Medicine, Loyola University Chicago, Maywood, Illinois 60153, USA.
Alcohol Clin Exp Res. 2000 Oct;24(10):1550-6.
Chronic ethanol abuse causes testicular atrophy and male infertility in alcoholic men. It is well known that ethanol exposure disrupts the hypothalamic-pituitary-gonadal axis, adversely affects the secretory function of Sertoli cells, and produces oxidative stress within the testes. It is still not clear what cellular mechanisms are responsible for the morphologic alteration of the testes that results in a reduction of testicular mass as a consequence of ethanol exposure. The hypothesis tested was that ethanol enhances apoptosis of testicular germ cells.
In the experiments of chronic ethanol exposure, male Sprague Dawley rats (Harlan Sprague Dawley, Inc., Indianapolis, IN) were fed Liber-Decarlie liquid diet for 9 weeks. In the experiments of acute ethanol exposure, a small volume of 20% ethanol solution was administered by intratesticular injection. Both 3'-end labeling of isolated testicular deoxyribonucleic acid (DNA) and labeling of apoptotic cells in situ by the terminal deoxynucleotidyl transferase-mediated deoxyuridine 5'-triphosphate nick end-labeling method were used to determine apoptosis rates within the testes. The expression of proteins involved in apoptosis was assessed by reverse transcription-polymerase chain reaction and by Western blotting.
The testes of rats that were fed an ethanol-containing liquid diet had more testicular DNA fragmentation than did those of animals that were fed an isocaloric control diet. Ethanol increased the number of apoptotic spermatogonia as well as spermatocytes. Direct intratesticular injections of ethanol solution enhanced testicular DNA fragmentation, suggesting an increase in apoptosis. Moreover, Fas ligand levels were increased within the testes of rats that were chronically fed ethanol. In vitro, ethanol treatment of cultured Sertoli cells enhanced the production of Fas ligand. In addition, testicular levels of p53 messenger ribonucleic acid were increased in rats that were chronically fed ethanol.
All of these observations suggest that ethanol enhances testicular germ cell apoptosis.
长期酗酒会导致男性酒精中毒者睾丸萎缩和不育。众所周知，乙醇暴露会破坏下丘脑 - 垂体 - 性腺轴，对支持细胞的分泌功能产生不利影响，并在睾丸内产生氧化应激。目前仍不清楚乙醇暴露导致睾丸形态改变进而使睾丸质量下降的细胞机制是什么。所验证的假说是乙醇会增强睾丸生殖细胞的凋亡。
在慢性乙醇暴露实验中，雄性斯普拉格 - 道利大鼠（Harlan Sprague Dawley公司，印第安纳波利斯，印第安纳州）喂食Liber - Decarlie液体饲料9周。在急性乙醇暴露实验中，通过睾丸内注射给予少量20%乙醇溶液。采用分离睾丸脱氧核糖核酸（DNA）的3'末端标记法和末端脱氧核苷酸转移酶介导的脱氧尿苷5'-三磷酸缺口末端标记法原位标记凋亡细胞来测定睾丸内的凋亡率。通过逆转录聚合酶链反应和蛋白质印迹法评估凋亡相关蛋白的表达。
喂食含乙醇液体饲料的大鼠睾丸DNA片段化程度高于喂食等热量对照饲料的动物。乙醇增加了凋亡精原细胞以及精母细胞的数量。睾丸内直接注射乙醇溶液可增强睾丸DNA片段化，提示凋亡增加。此外，长期喂食乙醇的大鼠睾丸内Fas配体水平升高。在体外，乙醇处理培养的支持细胞可增强Fas配体的产生。另外，长期喂食乙醇的大鼠睾丸中p53信使核糖核酸水平升高。
所有这些观察结果表明乙醇会增强睾丸生殖细胞凋亡。
