15-Hydroxyprostaglandin dehydrogenase in the bovine endometrium during the oestrous cycle and early pregnancy

Prostaglandins (PG) are primary regulators of reproductive function. In ruminants, the relative production of PGE2 and PGF2alpha determines the return to a new oestrous cycle or to the establishment of pregnancy in response to a viable embryo. PG action depends on biosynthesis, transport and interaction with their receptors, which are all expressed differentially during the oestrous cycle. PGs are, however, local mediators and thus the onsite degradation by enzymes such as 15-hydroxyprostaglandin dehydrogenase (HPGD), also known as 15-PGDH, is another factor to consider in the regulation of physiological action. Little information is available on PG catabolism in the endometrium during the oestrous cycle or early pregnancy. The purpose of this study was to clone the bovine 15-PGDH, produce the recombinant protein and generate a specific antibody to study its activity and its expression in the endometrium during the oestrous cycle. We have found that the bovine 15-PGDH is highly homologous to the rat and human isoforms. 15-PGDH is localized principally in the glandular epithelium and to a lesser extent in stromal and luminal epithelial cells. The enzyme expression is regulated during the oestrous cycle and it reaches its maximal level on days 16-18. Transient expression is observed in luminal epithelial and trophoblast cells on day 21 of pregnancy. The mRNA is expressed at a constant high level throughout the cycle. The activity of the recombinant 15-PGDH was also tested and was found comparable for PGF2alpha and PGE2. These data suggest that 15-PGDH contributes to the tight regulation of PG action in the endometrium especially at the critical period of recognition of pregnancy.