Determination of the target cells of activins and the mechanisms of FSH secretion stimulated by activins

本研究的目的是阐明激活素在脑垂体中的作用机制。激活素刺激卵泡刺激素分泌，但对黄体生成素分泌没有任何影响。但是激活素的作用机制是如何刺激卵泡刺激素分泌的还不清楚。本研究利用流式细胞仪和荧光显微镜系统阐明激活素复杂作用的机制。研究结果可能对生殖医学有重要意义。激活素A、AB、B的靶细胞在[Ca^<2+>]_i中对每一种下丘脑释放激素产生应答。其中50-70%的靶细胞为CHRH， 40- 7%为trh应答细胞。用细胞分选器和激光处理纯化细胞的结果相似。此外，一些激活反应细胞对GHRH和TRH都有反应。然后我们试图确定PRL分泌细胞、trh应答细胞和促性腺激素之间的关系。斑点印迹分析结果显示，LH和FSH分泌细胞在PRL分泌细胞中的占比分别为6.23%和5.91%，PRL分泌细胞在LH和FSH分泌细胞中的占比分别为18.4%和15.5%。RHPA测定PRL分泌细胞中GnRH和TRH升高[Ca^<2+1>]_i。这些数据表明，在激活素的刺激下，转化为fsh分泌细胞的靶细胞属于生长激素或prl分泌细胞的一个亚群。由于这些细胞的数量很少，因此这些细胞的转化过程尚不清楚。

The purpose of the study is to clarify the mechanisms of the action of activin in the pituitary gland. Activin stimulates FSH secretion without eny effect on LH secretion. But the mechaanisms of the action how activin stimulates FSH secretion specifically is unknown. This sutdy was performed to clarify the mechanisms of the complicated effect of activin using FACS and fluorescence microscope system. The results of the study may have a important roles in reproductive medicine.The target cells of the activin A,AB,B were characterized by their responses in [Ca^<2+>]_i to each Hyopothalamic releasing hormone. 50-70% of the target cells of them were proved to be CHRH,and 40-7-%, TRH-respondirig cells. The results using purified cells by cell sorter and laser treatment were similar. Moreover some of tie activin-responding cells have response to both GHRH and TRH.Then we tired to determine the relationship between PRL secreting cells, TRH-responding cells, and gonadotrophs. The results of dot bloting assey revealed the populations of the LH and FSH secreting cells in the PRL secreting cells were 6.23% and 5.91% respectively, while the populations of the PRL secreting cells in the LH and FSH secreting cell were 18.4% and 15.5% respectively. GnRH as well as TRH increased [Ca^<2+1>]_i in the PRL secreting cells as determined by RHPA.These data suggests theat the target cells which transform itself to FSH-secretinng cells stimulated by the activin are in a subpopulation of GH or PRL-secreting cells. The process of the transformation of these cells was not clarified becaouse of the small population of these cells.