Abstract
Prostaglandins (PGs) are involved in many reproductive activities including luteolysis, maternal recognition of pregnancy, endometrial gene expression, conceptus development, and parturition in domestic animals. However, mechanisms by which PGE2 and PGF2alpha are modulated in the uterine endometrium and expression of ABCC4 and SLCO2A1, responsible for efficient transport of PGs across the cell membrane, in the endometrium during the estrous cycle and pregnancy are not fully understood in pigs. Therefore, we determined expression of ABCC4 and SLCO2A1, genes involved in transport of PGE2 and PGF2alpha in the uterine endometrium during the estrous cycle and pregnancy in pigs. ABCC4 and SLCO2A1 mRNAs were expressed in the uterine endometrium, most abundantly on Day 12 of pregnancy and during late pregnancy. Expression of ABCC4 mRNA and protein was localized mainly to uterine luminal epithelial (LE) and glandular epithelial (GE) cells, and expression of SLCO2A1 mRNA and protein was expressed primarily in uterine LE and blood vessels. Expression of ABCC4 and SLCO2A1 mRNAs was also detected in conceptuses during early pregnancy. In addition, explant culture experiments showed that increasing doses of interleukin 1B (IL1B) with estrogen and progesterone increased levels of ABCC4 and SLCO2A1 mRNAs in the uterine endometrium. These results indicate that expression of genes responsible for transport of PGE2 and PGF2alpha are dynamically regulated in the uterine endometrium during pregnancy and that ABCC4 and SLCO2A1 play critical roles in supporting the establishment and maintenance of pregnancy by regulating PG transport at the maternal-fetal interface in pigs.