Reproduction Abstracts

The role of cumulus cells during in vitro maturation is essential for proper oocyte maturation and acquisition of its developmental competence. During development of ovarian follicle, cumulus cells undergo expansion, leading to extracellular matrix production (mainly hyaluronic acid), regulated by various intracellular signaling cascades. Moreover, cumulus cells metabolize glucose to pyruvate or lactate, substrates used by oocyte for its growth and maturation. We demonstrated before that lysophosphatidic acid (LPA) improved cumulus–oocyte complexes (COCs) quality via the influence on oocyte quality markers expression. Thus, the objective of the present study was to examine the effect of LPA on cumulus expansion, glucose uptake and expression of genes involved in cumulus expansion and glucose metabolism (AREG, EREG, BTC, ADAM, EGFR, TNFAIP6, PTGS2, PTX3, HAS2, GFPT, PFK, and LDH).

COCs were obtained by aspiration from subordinate ovarian follicles and matured in vitro in presence or absence of LPA (10⁻⁵ M) for 24 h. Following maturation, cumulus expansion was visually assessed, cumulus cells were separated from oocytes and used for gene expression analysis (real-time PCR). Glucose, lactate and lactate dehydrogenase (LDH) levels were determined in the maturation medium.

Although, cumulus expansion was similar in the control and the LPA-treated COCs, LPA simulated mRNA expression of genes critical for cumulus expansion from the epidermal growth factor (EGF)-like family: amphiregulin (AREG) and epiregulin (EREG). Moreover, LPA stimulated glucose uptake, lactate production and LDH concentration in COCs. These results suggest that LPA stimulates cumulus expansion by enhancement of glucose metabolism and controlling the expansion-related genes: AREG and EREG in cumulus cells.