Involvement of apoptosis in the induction of germ cell degeneration in adult rats after gonadotropin-releasing hormone antagonist treatment.
Involvement of apoptosis in the induction of germ cell degeneration in adult rats after gonadotropin-releasing hormone antagonist treatment.
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DOI：
10.1210/endo.136.6.7750502
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发表时间：
1995-06
期刊：
影响因子：
4.8
通讯作者：
A. Hikim;Charles Wang;A. Leung;R. S. Swerdloff
中科院分区：
文献类型：
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作者：
A. Hikim;Charles Wang;A. Leung;R. S. Swerdloff
在包括人类在内的成年哺乳动物中，生殖细胞死亡在精子发生过程中非常明显，并且在精子输出中发挥着关键作用。然而，这种现象背后的可能机制仍然知之甚少。细胞凋亡是一种程序化的生理过程，细胞自发死亡或响应特定生理刺激水平的变化而死亡。此前，我们报道了通过 GnRH 拮抗剂 (GnRH-A) 治疗早期剥夺促性腺激素和睾酮，随后睾丸中生殖细胞发生阶段性特异性退化。在这项研究中，我们研究了细胞凋亡在诱导生殖细胞变性中的可能参与。成年雄性大鼠每天注射 Nal-Glu GnRH-A (1 mg/kg BW)，持续 0（对照）、2 或 5 天。通过高分辨率光学显微镜以及生殖细胞变性测定来评估生殖细胞变性的发生。细胞凋亡的发生特征在于：1）琼脂糖凝胶电泳后检测核小体间DNA片段，2）直接免疫过氧化物酶检测特定细胞类型中地高辛标记的基因组DNA。 GnRH-A 治疗开始 5 天后，检测到生殖细胞变性的最早形态学迹象，包括前细线期和粗线期精母细胞、第 7 步精子细胞（在第 VII 阶段）和第 19 步精子细胞（在第 VII 和 VIII 阶段）。生殖细胞变性的发生进一步伴随着低分子量DNA片段化程度的显着增加。在此时间范围内原位检测细胞凋亡完全证实了观察到的特定生殖细胞的阶段相关变性。这些结果表明细胞凋亡提供了睾丸中生殖细胞因缺乏激素刺激而死亡的基本机制。
In adult mammals, including man, germ cell death is conspicuous during spermatogenesis and plays a pivotal role in sperm output. The possible mechanism(s) underlying this phenomenon remains, however, poorly understood. Apoptosis is a programmed physiological process by which cells die either spontaneously or in response to changes in the levels of specific physiological stimuli. Previously, we reported that early deprivation of gonadotropin and testosterone by GnRH antagonist (GnRH-A) treatment is followed by a stage-specific degeneration of germ cells in the testis. In this study, we examined the possible involvement of apoptosis in the induction of germ cell degeneration. Adult male rats were given a daily injection of Nal-Glu GnRH-A (1 mg/kg BW) for 0 (control), 2, or 5 days. The onset of germ cell degeneration was assessed by high resolution light microscopy as well as by a germ cell degeneration assay. The occurrence of apoptosis was characterized by 1) detection of internucleosomal DNA fragmentation after agarose gel electrophoresis, and 2) direct immunoperoxidase detection of digoxigenin-labeled genomic DNA in specific cell types. The earliest morphological signs of germ cell degeneration involving preleptotene and pachytene spermatocytes, step 7 spermatids (at stage VII), and step 19 spermatids (at both stages VII and VIII) were detected 5 days after the commencement of GnRH-A treatment. The onset of germ cell degeneration was further accompanied by a significant increase in the degree of low mol wt DNA fragmentation. In situ detection of apoptosis within this time frame fully corroborates the observed stage-related degeneration of specific germ cells. These results suggest that apoptosis provides the basic mechanism by which germ cells die in the testis in response to a lack of hormonal stimulation.