Effects Of Ghrelin On The Early Ovine Embryo Development

Ghrelin is a brain-gut peptide containing28amino acid residues which was found in the gastric tissue of rat by a Japanese scientist Kojima with the method of immunohistochemistry in1999. It is the endogenic ligand of Growth hormone secretagogue receptor(GHS-R). Recently, more and more evidence shows Ghrelin has significant adjust function for the reproductive activity of mammal animals with the discoveries of Ghrelin in the uterus, fallopian tube, cervix, reproductive tract, oocytes and early embryos of mammal animals, and with the in depth study of relative mechanical of Ghrelin.Study found Ghrelin has significant function for the development of embryo though there is only a few reports about the effects of Ghrelin on the embryo development to now. In order to investigate the relationship between Ghrelin and the development of early ovine embryo, the early ovine embryo were cultured in4kinds of embryo developmental solution adding Ghrelin, addingD-Lys3-GHRP-6, adding both Ghrelin and D-Lys3-GHRP-6,control group,13concentration gradient groups. The embryo development situation were observed, the embryo cleavage rate were statisticed. It is found that exogenous Ghrelin adding has no significant auxo-action for embryo development. But adding D-Lys3-GHRP-6, block the Ghrelin receptor, the cleavage rate of the4-cells^8-cells embryo will decrease significantly by. And it is released that the dose of endogenous Ghrelin is enough for embryo development at the early stage of ovine embryo.Base on the results, the signal pathway MAPK is introduced to investigate the possible function mechanical of Ghrelin on the development of early ovine embryo,The relative expression of key adjust protein ERK1, ERK2and P90rsk of MAPK were tested in the blocked2-cells,4-cells,8-cells and16-cells embryos by Q-PCR. And the2scale genes Bcl-2and Bax which are used to evaluate the happening of cell apoptosis were tested,too. We get the following conclusions:Ghrelin can promote the mRNA expression of the ERK1, ERK2, p90rsk, and this function can be block by D-Lys3-GHRP-6,200ng/mL is the best dose. It revealed that Ghrelin mainly cascade activate ERK1, ERK2kinase through MAPK pathway, then promoing the activity of p90rsk, and the activated p90rsk can bring the signal into the nuclear to start a series of nuclear transcript factores. Ultimately realized the mechanism of promoting early ovine embryonic development.In addition,Ghrelin realized the promote function on early ovine embryo development by adjusting the expression of cell apoptosis gene in tow directions inhibit the expression of Bax gene and promote the expression of Bcl-2gene. And it can be antagonistic by adding D-Lys3-GHRP-6, or block the expression of GHS-R. No expression of Bcl-2mRNA in the groups which have no expression of GHS-R mRNA. It suggest Ghrelin has significant function for the expression of Bcl-2mRNA at the early ovine embryos. And it further proved Ghrelin has significant function of anti-apoptosis on the development of early ovine embryos.