Research progress on the role of prostaglandin E₂ in ovulation and its mechanism

Prostaglandin E₂ (PGE₂) is mainly synthesized by granulosa cells and is a key intrafollicular mediator of ovulation in many mammalian species. In ovulation process, luteinizing hormone (LH) sharply increases and induces granulosa cells to synthesize PGE₂ via cyclooxygenase-2 (COX-2) and prostaglandin E synthase (PGES). After released to extracellular space, PGE₂ combines to the receptor 2 (PTGER2) and PTGER4 on cumulus cells and induces mitogen activated protein kinase (MAPK) phosphorylation, increases the intracellular cAMP level and activates the protein kinase B (PKB) and MAPK pathway, so as to promote the occurrence of ovulation. The abnormal regulation of PGE₂ is associated with a variety of ovulatory disorders, such as polycystic ovary syndrome (PCOS) and luteinized unruptured follicle syndrome (LUFS).