Murdoch W J
Department of Animal Science, University of Wyoming, Laramie 82071, USA.
Biol Reprod. 1996 May;54(5):1135-40. doi: 10.1095/biolreprod54.5.1135.
Indirect immunofluorescence light microscopy was used to monitor temporal perturbations in the microtubular (tubulin) system of granulosa/lutein cells in paraffin-embedded sections of periovulatory follicles and corpora lutea of sheep. Estrogen-active granulosa cells of preovulatory follicles not yet exposed to the gonadotropin surge immunostained intensely for tubulin. Immunostaining of the microtubular matrix diminished after the onset of the surge and coincident with an abrupt fall in follicular estradiol production. A transient period of microtubular retraction was characterized by low-level steroid hormone output. Microtubules reappeared with the approach of ovulation and increase in follicular progesterone biosynthesis (luteinization). Treatment of animals during the preovulatory period with colchicine, a drug that binds specifically with tubulin and interferes with microtubular assembly, obstructed the follicular shift toward progesterone. Microtubular dynamics (polymerization<->depolymerization) evidently underpin fundamental mechanisms of follicular steroidogenesis. Finally, corpora lutea were isolated from ewes on Day 10 of the estrous cycle before (0 h) and after administration of prostaglandin (PG) F2 alpha. There was a small augmentation in luteal concentrations of progesterone at 2 h, followed by a sharp decrease from 4 to 16 h. Luteal weights were reduced (structural regression) at 24 h. Sections of large (PG-sensitive) steroidogenic cells of control corpora lutea typically displayed a radiating microtubular network. After administration of PGF2 alpha, tubular matrices of large cells were scant; mitochondrial clustering was evident in transmission electron micrographs. Affixed disassembly of the cytoskeleton of large luteal cells may be a heretofore unrecognized event in the biomechanics of functional luteolysis--perhaps uncoupling cholesterol translocation to mitochondrial cytochrome P450 side-chain cleavage.
采用间接免疫荧光光学显微镜，监测绵羊排卵前卵泡和黄体石蜡包埋切片中颗粒/黄体细胞微管（微管蛋白）系统的时间扰动。尚未受到促性腺激素激增影响的排卵前卵泡中具有雌激素活性的颗粒细胞，其微管蛋白免疫染色强烈。促性腺激素激增开始后，微管基质的免疫染色减弱，同时卵泡雌二醇分泌量急剧下降。微管短暂收缩期的特征是类固醇激素分泌水平较低。随着排卵临近和卵泡孕酮生物合成增加（黄体化），微管重新出现。在排卵前期用秋水仙碱处理动物，秋水仙碱是一种与微管蛋白特异性结合并干扰微管组装的药物，它阻碍了卵泡向孕酮的转变。微管动力学（聚合<->解聚）显然是卵泡类固醇生成基本机制的基础。最后，在发情周期第10天，在给予前列腺素（PG）F2α之前（0小时）和之后，从母羊中分离黄体。黄体孕酮浓度在2小时时有小幅升高，随后在4至16小时急剧下降。24小时时黄体重量减轻（结构退化）。对照黄体中大型（对PG敏感）类固醇生成细胞的切片通常显示出放射状微管网络。给予PGF2α后，大型细胞的微管基质稀少；在透射电子显微镜照片中，线粒体聚集明显。大型黄体细胞细胞骨架的固定拆卸可能是功能性黄体溶解生物力学中迄今未被认识的事件——也许是将胆固醇转运至线粒体细胞色素P450侧链裂解的解偶联。
