Role of WNT/BETA-CATENIN signal transduction pathway in rat follicular development and luteal function

MARTA TESONE

Oxford

Congreso; Society for Reproduction and Fertility Annual Conference; 2015

ROLE OF SUVIVAL AND ANGIOGENIC FACTORS IN FOLLICLE AND CORPUS LUTEUM DEVELOPMENTMARTA TESONEINSTITUTO DE BIOLOGIA Y MEDICINA EXPERIMENTAL (IBYME-CONICET)Ovarian follicular development and regression is a continuous and cyclic process that depends on a number of endocrine, paracrine and autocrine signals. The cyclic recruitment and selection of follicles eventually leads to the formation of one or more preovulatory follicles, whose number varies in each species. In the first days of the female ovarian cycle, the circulating levels of FSH increase and, as a consequence, a group of antral follicles escapes the process of programmed cell death (apoptosis) that would lead them to follicular degeneration (atresia). It is postulated that the dominant follicle possesses a higher sensitivity to FSH, leading to higher production of estradiol, inhibin and local growth factors, as compared with the regressing follicles. Estrogens exert a positive feedback mechanism on the pituitary gland that triggers the preovulatory discharge of LH. These processes, involving a number of locally- produced factors, result in the selection and maturation of the dominant follicles that finally ovulate. After ovulation, the corpus luteum (CL) is the transient endocrine gland that forms from the remaining wall of the ovarian follicle. The CL?s main function is to secrete the steroid hormone progesterone (P), which is essential for implantation of the blastocyst and maintenance of pregnancy in mammals. However, if pregnancy does not occur or when it is no longer required for maintenance of pregnancy, the CL ceases to produce progesterone and regresses in a process called luteolysis. Prostaglandin F2 alpha (PGF2-alpha) is a uterine-derived factor that initiates luteolysis in most nonprimate species. During luteolysis the death of luteal cells is preceded by a loss of their capacity to synthesize and secrete P. All these processes (follicular growth and regression; CL development and luteolysis) require dynamic changes in the ovarian vascular network. Angiogenesis is the process of blood vessel formation in which new vessels sprout and mature from a pre-existing vasculature. We have demonstrated that ovarian angiogenic factors (VEGF-A and angiopoietins) have a protective role on rat follicular atresia mediated by the inhibition of apoptotic process. In addition, we have described that the Notch signaling pathway also has an important role on follicular and corpus luteum development. (Financial Support: CONICET, ANPCYT and UBA).