Study of lysophosphatidic acid receptors (LPARs) in buffalo uterus demonstrated upregulation of LPAR1 and LPAR6 in early pregnancy

Lysophosphatidic acid (LPA) is an important factor involved in embryo implantation and pregnancy establishment in humans and domestic livestock. LPA exerts its action through six G-protein-coupled receptors (LPA1-LPA6). We investigated the types of LPA receptors expressed in buffalo uterus and also their differential expression in the nonpregnant, and early-pregnant endometrium. The nonpregnant, and early-pregnant (<42 days) uteri were collected from the local slaughterhouse. RT-PCR experiments detected mRNAs of all the six LPA receptors (LPAR1-LPAR6) in both nonpregnant, and early-pregnant endometrial tissues. Their comparative profiling by real-time PCR revealed that the early pregnant endometrium expressed more mRNAs of LPAR1 and LPAR6. All the mRNA fragments were sequenced and submitted to Genbank, NCBI. Western blot studies also showed a similar expression pattern of these two receptor proteins, including higher expression of both LPA1 and LPA6 proteins during early pregnancy. And between these two receptors, LPA6 upregulation was more pronounced than LPA1. In immunohistochemistry, these receptors were found to be localized in the endometrial glandular epithelial cells of both types of uterus. Level of LPA was also higher in early pregnant endometrial tissues. In summary, our study demonstrated expression of all the six LPAR mRNAs in buffalo uterus, wherein the early-pregnant uterus did express comparatively higher mRNA as well as protein of LPA1 and LPA6, indicating their role in pregnancy. The more pronounced expression of LPA6 possibly indicates its greater contribution to mediating LPA signaling in early pregnancy (29-42 days) of buffalo.