Arachidonic acid regulation of the cytosolic phospholipase A2α/cyclooxygenase-2 pathway in mouse endometrial stromal cells

Objective: To investigate the role of arachidonic acid (AA) in mouse endometrial stromal cells. Design: Experimental animal study. Setting: University research laboratory. Animal(s): Sexually mature female CD1-strain mice. Intervention(s): Primary culture of endometrial stromal cells. Main Outcome Measure(s): Western blot and real-time polymerase chain reaction for gene expression and/or phophorylation analysis. Luciferase assay for Cox-2 promoter analysis. Result(s): AA-derived prostaglandins play important roles during embryo implantation and decidualization. However, the function of AA itself in reproduction is largely unknown. In this study, exogenous AA stimulated cPLA(2 alpha) phosphorylation and COX-2 expression, mainly through ERK1/2 in mouse endometrial stromal cells, and p38 inhibitor modestly inhibited cPLA(2 alpha) phosphorylation induced by AA. The induction of COX-2 by AA was diminished by short interfering RNA against C/EBP beta and inhibitory C/EBP beta (LIP). C/EBPb binding site at -872- -864 of Cox-2 promoter contributes to Cox-2 promoter activation induced by C/EBPb transfection. The expression of C/EBPb protein induced by AA was inhibited by p38 inhibitor, and the phosphorylation of C/EBP beta induced by AA was inhibited by p38 inhibitor and ERK1/2 inhibitor. A nonmetabolized analogue of AA (ETYA) also enhanced cPLA(2 alpha) phosphorylation and COX-2 expression. The activation of cPLA(2 alpha)/COX-2 by AA was not inhibited by COX inhibitor indomethacin. Conclusion(s): AA can induce cPLA(2 alpha)/COX-2 pathway activation in mouse endometrial stromal cells. (Fertil Steril (R) 2012;97:1199-1205. (C) 2012 by American Society for Reproductive Medicine.)