Expression Of EGFR,IGF-Ⅰand IGF-Ⅰ R In Bovine Preimplantation Embryo And Effect Of EGF,IGF-Ⅰ On Muturation Of Bovine Oocyte In Vitro

EGF (epidermal growth factor) and IGF- I (insulin-like growth factor-I) are important growth factors to the development of preimplantation embryo ,muturation of oocyte and development of preimplantion embryo are regulated by EGF and IGF- I systems in direct or indirect manner. The aim of this study was to illuminate the expression of proteins of the EGFR, IGF- I and IGF- I R in preimplantation bovine embryos by using indirect immunofluorescence and laser scanning confocal microscopy. Furthermore,Bovine follicular oocytes were matured in vitro and for 22 h in TCM-199 (tissue culture medium-199) without or with EGF (1,10,50 ng/ml), IGF-I (10,50,100 ng/ml). At the end of the culture period,the nuclear muturation rates were observed. This study was carried out to identify the possible effects of EGF and IGF-I to nuclear maturation in bovine oocytes matured in vitro and optimistic concentration that added in muturation medium.(1) There is not existing EGF protein in bovine preimplantation embryo ,but EGFR protein could be detected in this period. It was found EGFR protein existed in every stage(from two cell to blastula )and located on cell membrane. The protein expression intensity increasd with embryo development. There are experiments demonstrated EGF protein exists in uterus and oviduct during the bovine preimplantation embryo developmental period, it indicated that EGFcould effect preimplantation embryo development by paracrine manner. (2)Immunofluorescence result demonstrate that IGF- I system have expressed in preimplantation embryo deveopmental period. The proteins expression intensity also increasd with embryo development. IGF- I can be detected in the cell membrance and cell plasma, IGF- I R was located in cell membrance. The results indicated that IGF- I system have biological action to bovine embryo development. (3)EGF concentrated in Ing/ml, 10ng/ml, 50ng/ml,100ng/ml,200ng/ml and IGF-I concentrated in 10ng/ml, 50ng/ml, 100ng/ml,150ng/ml,200ng/ml were added in muturation medinm, then the nuclear muturation rates after cultured 22 hours were evaluated. The rates of nuclear maturation supplemented with EGF were 36.73%,42.18%,56.18%,53.67%,56.5% respectively,were all higher than the rate of contrast(34.04%).The rates of nuclear maturation supplemented with IGF- I were 38.46%,46.94%,58.73%,55%,58.7% respectively, 50ng/ml,100ng/ml,150ng/ml,200ng/ml IGF- I werer higher than contrast(38.60%). The muturation rate was 75% when 50ng/ml EGF plus 100ng/ml IGF- I were added in muturation medium, and significantly higher than that of constrast(36.54%, P<0.01). The result demonstrated EGF, IGF-I could increase the bovine oocyte nuclear muturation rate and the effect were saturable (concentration=50ng/mlEGF,100ng/mlIGF- I ) .