Mendis-Handagama S M, Watkins P A, Gelber S J, Scallen T J
Department of Animal Science, University of Tennessee College of Veterinary Medicine, Knoxville 37996, USA.
Tissue Cell. 1998 Feb;30(1):64-73. doi: 10.1016/s0040-8166(98)80007-4.
We investigated the chronic effects of luteinizing hormone (LH) treatment on adult rat Leydig cell structure and function. Two groups of sexually mature male Sprague-Dawley rats were used; controls and rats implanted subdermally with LH-filled Alzet miniosmotic pumps (delivers 24 micrograms of LH per day). After 2 weeks of LH treatment, testes of these rats were fixed by 2.5% glutaraldehyde in cacodylate buffer and processed and embedded in epon-araldite for light and electron microscopy and electron microscopic immunocytochemistry. Using light microscopic stereology, Leydig cell volume density, number of Leydig cells per testis, and the average volume of a Leydig cell were determined. Additionally, the organelle volumes per Leydig cells were quantified by electron microscopic stereology. Sterol carrier protein-2 (SCP2) and catalase in Leydig cells were immunolocalized via the Protein A gold method. Isolated and purified Leydig cells were used to determine the LH-stimulated (100 ng/ml) testosterone secretory capacity per Leydig cell in vitro and to compare the SCP2 and catalase content in equal numbers of Leydig cells using immunoblot analysis. After 2 weeks of LH-treatment, Leydig cell number per testis and the average volume showed a two-fold increase. All organelles tested, except the lipid droplets, were significantly (P < 0.05) increased two-fold in volume per Leydig cell. Testosterone secretory capacity per Leydig cell was increased approximately six-fold in the LH-treated group. Immunolabeling studies showed that the intraperoxisomal SCP2 content was significantly greater (P < 0.05) and the catalase content was significantly lower (P < 0.05) in LH-treated rats compared to to controls. Immunoblots showed that the total SCP2 content per cell is greater and the catalase content per cell is similar in Leydig cells of LH-treated rats compared to controls. In summary, chronic LH treatment produced hyperplasia, hypertrophy and increased testosterone secretory capacity in leydig cells of adult rats. However, the increase in the testosterone secretory capacity per Leydig cell exceeds the degree of Leydig cell hypertrophy, which cannot be explained by a generalized increase in volumes of all Leydig cell organelles in the LH-treated rats. These results also suggested that chronic LH treatment induces differential synthesis of peroxisomal proteins, i.e. an increase in SCP2 synthesis and no change in catalase synthesis. This resulted in peroxisomes rich in SCP2 and lower in catalase. Significance of these effects in relation to the increased steroidogenic capacity of Leydig cells remains to be determined.
我们研究了促黄体生成素（LH）治疗对成年大鼠睾丸间质细胞结构和功能的慢性影响。使用了两组性成熟的雄性斯普拉格-道利大鼠；一组为对照组，另一组大鼠皮下植入填充LH的Alzet微型渗透泵（每天释放24微克LH）。LH治疗2周后，将这些大鼠的睾丸用2.5%戊二醛在二甲胂酸钠缓冲液中固定，然后进行处理并包埋在环氧树脂-阿拉地特中，用于光镜和电镜以及电镜免疫细胞化学观察。使用光镜体视学方法，测定了睾丸间质细胞体积密度、每个睾丸的间质细胞数量以及一个间质细胞的平均体积。此外，通过电镜体视学方法对每个间质细胞的细胞器体积进行了量化。通过蛋白A金标法对间质细胞中的固醇载体蛋白-2（SCP2）和过氧化氢酶进行免疫定位。分离纯化的间质细胞用于测定体外每个间质细胞对LH刺激（100 ng/ml）的睾酮分泌能力，并使用免疫印迹分析比较等量间质细胞中SCP2和过氧化氢酶的含量。LH治疗2周后，每个睾丸的间质细胞数量和平均体积增加了两倍。除脂滴外，所有测试的细胞器每个间质细胞的体积均显著（P < 0.05）增加了两倍。LH治疗组中每个间质细胞的睾酮分泌能力增加了约六倍。免疫标记研究表明，与对照组相比，LH治疗的大鼠过氧化物酶体内SCP2含量显著更高（P < 0.05），而过氧化氢酶含量显著更低（P < 0.05）。免疫印迹显示，与对照组相比，LH治疗的大鼠间质细胞中每个细胞的总SCP2含量更高，而每个细胞的过氧化氢酶含量相似。总之，慢性LH治疗导致成年大鼠睾丸间质细胞增生、肥大并增加了睾酮分泌能力。然而，每个间质细胞睾酮分泌能力的增加超过了间质细胞肥大的程度，这无法用LH治疗大鼠所有间质细胞细胞器体积的普遍增加来解释。这些结果还表明，慢性LH治疗诱导过氧化物酶体蛋白的差异合成，即SCP2合成增加而过氧化氢酶合成无变化。这导致过氧化物酶体富含SCP2而过氧化氢酶含量降低。这些影响与间质细胞类固醇生成能力增加的关系的意义仍有待确定。
