The role of growth factors in the regulation of porcine oocyte maturation in vitro
1998
Sirotkin, A. | Makarevic, A. | Pivko, J. (Research Institute of Animal Production, Nitra (Slovak Republic)) | Dukesova, J. | Kubek, A. (Slovak Agricultural Univ., Nitra (Slovak Republic))
The aim of our in-vitro experiments was to study the action of exogenous insulin-like growth factor - I (IGF-1), IGF-2 and epidermal growth factor (EGF) (10 ng/ml medium) on nuclear maturation (meiosis) and production of protein kinase A (PKA), possible messenger of growth factor action, on cultured porcine oocytes. Nuclear maturation was assessed immunocytochemically according to the structure of meiotic chromosomes stained with Giemza dye. Intracellular level of PKA was evaluated immunocytochemically using antisera against cathalytic and regulatory subunits of this enzyme. It was observed that oocytes surrounded by developed Cumulus oophorus showed significantly higher rate of reinitiation and completion of meiosis than oocytes without cumulus investment. IGF-1, IGF-2 and EGF increased the proportion of both cumulus-enclosed and cumulus-free oocytes reinitiated and completed meiosis in vitro. IGF-1 was the most potent stimulator of oocyte nuclear maturation. Furthermore, it was demonstrated that IGF-1 and, in a lesser extent, IGF-2 increased the proportion of cumulus-enclosed oocytes contained visible immunoreactive cathalytic and regulatory subunits of PKA. EGF did not influence PKA content in the oocytes. Our observations suggest that (1) Cumulus oophorus supports the nuclear maturation of porcine oocytes, (2) the growth factors IGF-(, IGF-2 and EGF are stimulators of oocyte nuclear maturation, (3) effect of growth factors on oocyte is not mediated by cumulus investment, and (4) both cathalytic and regulatory subunits of PKA arc possible mediators of IGF-1, IGF-2, but not of EGF action on porcine oocytes
显示更多 [+] 显示较少 [-]