The quality of oocytes is altered by endometriosis in a mouse model

WETTEN P.A.; MICHAUT, M.A.; KLINSKY LAHOZ O.G.; SAGEGH F.; CASAIS M.

Congreso; XXXI Reunión Anual Virtual Sociedad Chilena de Reproducción y Desarrollo; 2020

Endometriosis is an estrogen-dependent inflammatory condition that affects women in their reproductive period causing infertility and pelvic pain. It is a chronic disease characterized by the presence of endometrial-like tissue outside the uterine cavity. The mechanisms of endometriosis-related infertility remain largely unknown. Approximately 10% of women in reproductive age are affected by endometriosis-associated infertility and, although causes like anatomical alterations or implantation problems have been evaluated, there is still no consensus on whether endometriosis affects the oocyte quality. Therefore, the aim of this work was to analyze the effect of endometriosis on the oocyte quality using a mouse model. CF-1 female mice of 8- 12 weeks were used to develop the endometriosis model through an autologous surgical induction. After 4 weeks of development, endometriotic and control females were hormonally stimulated to obtain mature oocytes. Because endometriosis generates a pro-inflammatory environment that possibly alters cellular energetic pathways, we first examined the mitochondrial function since it is responsible for cellular metabolism. We evaluated the mitochondrial membrane potential (MMP) and ATP levels in live mature oocytes using fluorescent probes. No differences were found in the MMP level; however, the ATP level was significantly reduced in endometriotic oocytes. Since the cortical actin cytoskeleton undergoes dynamic changes during meiotic progression of the oocytes and of mouseactivation, we analyzed cortical actin using a fluorescent marker. Results showed that cortical actin was thickened in endometriotic oocytes compared to control cells. This led us to hypothesize that cortical granule exocytosis (CGE), a secretory process that avoids polyspermy, might be altered. We analyzed CGE through a functional assay in which oocytes were parthenogenetically activated by strontium. Results showed that endometriotic oocytes were not able to respond to the activator when compared with control oocytes. Altogether, these results show that endometriosis alters the oocyte quality.