The Effect Of Growth Hormone On The Expressions Of VEGF, LIF, Integrinα_vβ₃, MMP-9 And TIMP-1 During Secretory Period And Implantation Window Phase In Mouse Endometrium

Background and ObjectiveSuccessful implantation includes steps of recognition, location, adhesion, penetrating, and finally implanted into endometrial matrix. During this process, both embryo and endometrium undergo synergeticadaptation in time and space. The result is that on one side, embryos gradually develop, mature, and get into an "invasive state"; on the other side, the endometrium turns into "receptive state". Thus, the synergetic adaptation is crucial for successful implantation. Moreover, it is also a target site by which the implantation is regulated. The recent study shows that except for the fine regulation of estrogen and progesterone on embryo and endometrium, both embryo and endometrium themselves can secrete many kinds of protein factors, such as vascular endothelial growth factor (VEGF), leukaemia inhibitory factory (LIF ) , epidermal growth factor (EGF) , integrins, matrix metalloproteinases (MMPs) , and et al. These protein factors act as autocrine or paracrine manner to co-regulate the specific physiological state of pragnance. It is indicated that the expression and secretion levels of certain kinds of protein factors are closely related to the growth, development, and implantation capability. Thus, the levels of implantation-related factors may be a practical functional marker in evaluating the developmental state, implantation capability, as well as the receptivity of endometrium. Growth hormone(GH) is an important hormone which regulates growth and development. The recent study shows that GH also take part in reproduction of female animals and it has roles in reproductive function. It is required for sexual differentiation, pubertal maturation and it participates in gonadal steroidogenesis, gametogenesis, sexual differentiation and secretion and action of luteinizing hormone (LH) and follicule-stimulating hormone(FSH). GH may facilitate ovulation by increasing sensitivity to gonadotrophins and by reducing the incidence of apoptosis in preovulatory ovarian follicles. GH, directly or indirectly via IGF-I, regulates reproductive function and GH administration can increases the clinical rate of pregnancy by improving the quality of occyot and the endometrial receptivity.There are few studies about the effect of GH on endometrium. The purpose of my research is to study the effect of GH on the expressions of VEGF, LIF, integrinsαvβ₃, MMP-9 and tissue inhibitor of metalloproteinase-1 (TIMP-1) in endometrium of mouse during secretory period and implantation window phase, and to find the strategies to improve the endometrial receptivity, and increasing the clinical pregnancy rate.Materials and MethodsOne hundred mice were divided into four groups randomly: Normal saline(NS) group of secretory period, NS group of implantation window phase, GH group of secretory period and GH group of implantation window phase. The expressions of VEGF, LIF, integrinavp3, MMP-9 and TIMP-1 in mouse endometrium of the four groups were examined by immunohistochemistry techniques and semi-quantified H-SCORE assay. The data were analysed by SPSS 11.5 for windows. Comparison of the average in two groups was performed by t-test(α=0.05).Results(1) VEGF LIF integrinαvβ₃ MMP-9 and TIMP-1 all located in endometrial luminal epithelial cells and glandular epithelial cells;(2) The expressions of VEGF LIF integrinαvβ₃ MMP-9 and TIMP-1 of mouse endometrium during implantation window phase of pregnant mice were stronger than that of secretory period of non-pregnant mice, the difference between them were significant (P<0.01). The value of the expression of MMP-9/TIMP-1 are markedly more significant in the normal implantation phase endometrium of pregnant mice than that in secretory period of non-pregnant mice (P<0.01) ;(3) In secretory period of non-pregnant mice, the expressions of VEGF LIF integrinα_vβ₃, MMP-9 and TIMP-1 in NS group were lower than that in GH group, the difference between them were significant(P<0.05), while no difference was found in the values of the expression of MMP-9/TIMP-1 in the two groups (P>0.05);(4) The endometrial VEGF, LIF, MMP-9 and TIMP-1 were present in cytoplasm during the window of implantation. The immunostaining intensities of luminal epithelial were stronger than that of glandular. More stronger expressions of VEGF, LIF, MMP-9 and TIMP-1 were found in GH group than those in NS group of implantation window phase of pregnant mice, the difference between them were significant(P<0.05).While no difference was found in the values of the expression of MMP-9/TIMP-1 in the two groups (P>0.05), Both values are close to 1.Conclusions(1) The immunostains of VEGF, LIF, integrinα_vβ₃, MMP-9 and TIMP-1 in endometrium of mouse during implantation window phase were positve which maybe one of the important factors that affect on the endometrial receptivity and early blastocyst implantation;(2) The expression of MMP-9/TIMP-1 in implantation phase endometrium of pregnant mice was higher than that in secretory period of non-pregnant mice. This was probably helpful to the embryonic nidation. In implantation window phase of normal endometrium, both values of the expression of MMP-9/TIMP-1 in GH group and NS group were close to 1. That suggests there is a mobile banlance of MMP-9 and TIMP-1 in implantation window endometrium, which is benefit to the maintenance of early pregnancy;(3) GH could inhance the expressions of VEGF LIF, integrinα_vβ₃ MMP-9 and TIMP-1 in endometrium of mouse during secretory period and implantation window phase. Using GH may improve the endometrial receptrivity and clinic pregnancy rate.