Gregoraszczuk E L, Skalka M
Department of Animal Physiology, Jagiellonian University, Kraków, Poland.
Reprod Fertil Dev. 1996;8(6):961-7. doi: 10.1071/rd9960961.
To characterize thyroid hormone action in the ovary, the direct effect of triiodothyronine (T3) was investigated in vitro using a culture system of porcine theca cells (Tcs) and granulosa cells (Gcs) in mono- and co-culture (GT), the latter resembling follicles in vivo. The cells were cultured in the absence or presence of human chorionic gonadotrophin (hCG) with or without T3 (10(-7), 10(-9) or 10(-11) M). Follicular cells were obtained from follicles of different size (small, medium and large), and steroid secretion into the culture medium was detected by radioimmunoassay. T3 alone did not influence steroid secretion by Tcs and Gcs isolated from follicles that were small and medium in size. In preovulatory follicles, an increase in basal androgen secretion and a simultaneous decrease in oestradiol secretion were observed with Tcs and Gcs in both mono- and co-culture. T3 together with hCG decreased hCG-stimulated androgen secretion in Tcs isolated from medium-sized follicles and had a simultaneous stimulatory effect on hCG-stimulated oestradiol secretion by Gcs. In cultures of follicular cells obtained from large follicles, T3 decreased hCG-stimulated secretion of both androgen and oestrogen by Tcs and simultaneously stimulated oestradiol secretion in GT co-cultures. Thus, the interaction of T3 with gonadotrophin hormone modulated follicular steroidogenesis, depending on follicle size and cell type used in culture. The observed T3-induced increase in basal androgen secretion by Tcs could account for the atresia of follicles, since it is accompanied by a decrease in oestradiol secretion in GT co-culture. In its co-activity with hCG, an adequate level of T3 prevents excessive androgen production by Tcs, probably influencing aromatization processes in the follicle. An increase in hCG-stimulated oestradiol secretion in GT co-cultures is then observed. Further investigations are required to clarify whether this is linked with an effect on the aromatization processes occurring in the follicle.
为了描述甲状腺激素在卵巢中的作用，我们使用猪卵泡膜细胞（Tcs）和颗粒细胞（Gcs）的单培养和共培养（GT）体系进行体外研究，以探究三碘甲状腺原氨酸（T3）的直接作用，后者类似于体内的卵泡。细胞在无或有人类绒毛膜促性腺激素（hCG）以及有或无T3（10^(-7)、10^(-9)或10^(-11) M）的情况下进行培养。卵泡细胞取自不同大小（小、中、大）的卵泡，通过放射免疫测定法检测培养基中的类固醇分泌。单独的T3并不影响从小卵泡和中卵泡分离出的Tcs和Gcs的类固醇分泌。在排卵前卵泡中，无论是单培养还是共培养，Tcs和Gcs的基础雄激素分泌增加，同时雌二醇分泌减少。T3与hCG共同作用时，可降低从中等大小卵泡分离出的Tcs中hCG刺激的雄激素分泌，并同时对Gcs中hCG刺激的雌二醇分泌产生刺激作用。在从大卵泡获得的卵泡细胞培养物中，T3可降低Tcs中hCG刺激的雄激素和雌激素分泌，并同时刺激GT共培养物中的雌二醇分泌。因此，T3与促性腺激素的相互作用调节卵泡类固醇生成，这取决于培养中使用的卵泡大小和细胞类型。观察到的Tcs中T3诱导的基础雄激素分泌增加可能是卵泡闭锁的原因，因为在GT共培养中它伴随着雌二醇分泌的减少。在与hCG的协同作用中，适当水平的T3可防止Tcs过度产生雄激素，这可能影响卵泡中的芳香化过程。随后在GT共培养中观察到hCG刺激的雌二醇分泌增加。需要进一步研究以阐明这是否与对卵泡中发生的芳香化过程的影响有关。
