FSH,EGF,胰岛素促进小鼠卵母细胞体外减数分裂恢复机制的研究

FSH、EGF和胰岛素均对体外培养的小鼠卵母细胞的减数分裂的恢复起促进作用,而FSH的促进作用滞后,但作用后使卵丘细胞扩散。三者的促进作用似受卵巢颗粒细胞内游离钙和cAMP的调节。EGF和胰岛素可使培养的颗粒细胞内的cAMP水平降低;同时FSH使单个卵丘细胞内的游离Ca~(2 )水平降低,而胰岛素无影响。所以FSH、EGF和胰岛素诱发卵母细胞成熟的机制不同:EGF通过细胞内Ca~(2 )的升高和cAMP水平的下降促使卵母细胞的减数分裂恢复;FSH降低卵丘细胞内Ca~(2 )的水平,但由于卵丘细胞与卵母细胞之间的联系被打断,最终使GVBD发生;而胰岛素的作用只涉及胞内cAMP的变化。

A PRELIMINARY STUDY ON THE MECHANISM OF EGF,FSH,INSULIN'S EFFECT ON THE MEIOTIC DIVISION OF MOUSE OOCYTES

Mouse oocyte arrested GV stage were used to study the action of FSH, EGF and Insulin. on ihe meiotic resumption. FSH, EGF, and insulin could trigger the GVBD of mouse oocyte in vitro. Bnt the accclerating effect of FSH lagged behind other two faciors, while cumulus cells adhering to oocyte expanded after being exposed to FSH. Their action seem to be modu-lated by cytosolic free Ca2 or cAMP Ievel in granulosa cells. EGF and insulin decreased the cAMP level in granulusa cells. The cytosolic free Ca2 in single cumulus cell dropped below to normai Ievel when it was exposed to FSH, while insulin had no effect on the Ca2 level in cumulus cell. So the mechanisms of FSH, EGF and insulin inducing the maturation of oocytes were diferenti EGF induced GVBD through both cAMP descent and Ca2 increase pathways. Despite of the decreasing of the Ca2 level in cumulus cells, the relation between cumulus cells and oocyte was blockcd because of the expanding of cumulus cells, GVBD could also occur after long exposure to FSH. But the effect of FSH was not so great as that of EGF and insulin. While the effect of insulin was only related with cAMP pathway in granulosa cell and cumulus cell.