Blanco-Rodríguez J, Martínez-García C
Department of Cell Biology, School of Medicine, Valladolid University, Ramón y Cajal, Spain.
J Reprod Fertil. 1997 May;110(1):61-70. doi: 10.1530/jrf.0.1100061.
It is widely assumed that oestrogen administration in the male mimics hypophysectomy by suppressing gonadotrophin secretion. Nevertheless, oestradiol treatment can increase germ-cell apoptosis mainly at stages IV-X of the spermatogenic cycle, rather than at stage VII when apoptotic germ-cell death is mainly triggered by gonadotrophin withdrawal caused by hypophysectomy. Since the roles of testicular oestrogens in spermatogenic regulation, if any, are unknown, we re-evaluated the germ-cell types that undergo apoptosis after oestradiol treatment. Adult male rats were injected daily with 50 micrograms oestradiol, oestradiol plus testosterone propionate (25 mg every 3 days) or oestradiol plus human menopausal gonadotrophin (equivalent to 25 iu FSH plus 25 iu LH) for 15 days. Apoptosis was assessed by in situ 3'-end labelling of internucleosomal DNA fragments in plastic semithin sections; the germ-cell types involved were identified by high-resolution light microscopy. The quantitative analysis of our results shows that the apoptosis pattern elicited by oestradiol treatment of the seminiferous epithelium differs from that reported to be caused by gonadotrophin or testosterone withdrawal, suggesting a possible role for oestradiol in the modulation of germ-cell death in the adult testis of the rat.
人们普遍认为，雄性动物体内注射雌激素会通过抑制促性腺激素分泌来模拟垂体切除。然而，雌二醇治疗主要在生精周期的IV-X阶段增加生殖细胞凋亡，而不是在垂体切除导致促性腺激素撤退主要引发凋亡性生殖细胞死亡的VII阶段。由于睾丸雌激素在生精调节中的作用（如果有）尚不清楚，我们重新评估了雌二醇治疗后发生凋亡的生殖细胞类型。成年雄性大鼠每天注射50微克雌二醇、雌二醇加丙酸睾酮（每3天25毫克）或雌二醇加人绝经期促性腺激素（相当于25国际单位促卵泡激素加25国际单位促黄体生成素），持续15天。通过对塑料半薄切片中的核小体间DNA片段进行原位3'端标记来评估凋亡；通过高分辨率光学显微镜鉴定所涉及的生殖细胞类型。对我们结果的定量分析表明，雌二醇处理生精上皮引发的凋亡模式与据报道由促性腺激素或睾酮撤退引起的凋亡模式不同，这表明雌二醇在调节成年大鼠睾丸生殖细胞死亡中可能起作用。
