Lysophosphatidic acid action in the bovine corpus luteum -an in vitro study

We examined whether the CL is a site for lysophosphatidic acid (LPA) synthesis and/or a target for LPA action in the bovine reproductive tract. LPA concentrations in the CL tissue increased towards the end of the cycle and were stable during early pregnancy. No changes in the expression of LPA receptors (LPARs) occurred during the estrous cycle. The expressions of LPAR2 and LPAR4 on days 17-19 of pregnancy were higher than those on the respective days of the estrous cycle and higher than those on days 8-10 of pregnancy. LPA stimulated P4 synthesis via 3βHSD stimulation but did not modulate the interferon-tau (IFNτ) influence on P4 synthesis in steroidogenic cells. Moreover, we found LPA-dependent stimulation of IFNτ action on 2,5'-oligoadenylate synthase (OAS1) and ubiquitin-like IFN-stimulated gene 15-kDa protein (ISG15) expression. The present study demonstrated that the CL might be a site of LPA synthesis and target of LPA action in the bovine reproductive tract. We postulate that during the estrous cycle and early pregnancy, LPA exerts autocrine and paracrine effects on the CL mainly via LPAR2 and LPAR4. The stimulatory effect of LPA on P4 synthesis via 3βHSD stimulation and LPA-dependent stimulation of IFNτ action on OAS1 and ISG15 expression suggest that LPA is an additional auxiliary luteosupportive factor in steroidogenic cells.