Effect of serum and cumulus cell expansion on marker gene transcripts in bovine cumulus-oocyte complexes during maturation in vitro

Objective: To determine the distribution of transcripts encoding the FSH receptor (FSHr), LH receptor (LHr), connexin 43 (Cx43), cyclooxygenase-2 (COX-2), and prostaglandin E-2 receptors 2 and 3 (EP2 and EP3) within bovine cumulus-oocyte complexes (COCs) and denuded oocytes and investigate the influence of gonadotropins, serum, and cumulus cell expansion on the abundance of transcripts encoding these genes. Design: Prospective controlled animal study. Setting: University research laboratory. Patient(s): Animal models for human studies. Intervention(s): Cumulus-oocyte complexes were treated in culture with serum and gonadotropin-supplemented media to examine the effects to mRNA transcript levels. Main Outcome Measure(s): Variation in mRNA transcript levels. Result(s): Luteinizing hormone receptor, FSHr, and EP3 mRNAs were detected in intact COCs and not in cumulus cell-denuded oocytes, whereas Cx43, COX-2, and EP2 mRNAs were found in both COCs and oocytes. The relative abundance of marker gene mRNAs did not vary in media containing no additives or FSH alone, independent of whether the media induced cumulus cell expansion. However, the presence of serum in maturation media significantly decreased expression of all mRNAs except LHr. Conclusion(s): The relative abundance of COC mRNAs is altered by serum in the maturation inedium, which may si.-nifv Ion-term consequences for embryonic development.