Luteinizing hormone and ovarian steroids affect in vitro prostaglandin production in the equine myometrium and endometrium.

Abstract Prostaglandins (PGs) play crucial roles in the regulation of the oestrus cycle and establishment of pregnancy in animals. Luteinizing hormone (LH) and ovarian steroids are involved in regulating endometrial PG production in many species. Their effects on PG production and associated pathways in the mare myometrium and endometrium are the subjects of our interest. This study aimed to evaluate the specific effects of LH and ovarian steroids on equine myometrial and endometrial tissues on (i) PGE2 and PGF2α secretion and (ii) transcription of genes encoding specific enzymes responsible for PG synthesis, such as prostaglandin–endoperoxide synthase (PTGS2), PGE2 synthases (PGES), PGF2α synthases (PGFS), and PGI2 synthases (PGIS), using equine myometrial and endometrial explants. Equine myometrial and endometrial tissues were collected at the mid-luteal (n = 6) and follicular (n = 6) phases of the oestrus cycle and were exposed to: (1) vehicle (control), (2) arachidonic acid (AA, 50 ng/mL, positive control), (3) LH (10 ng/mL), (4) progesterone (P4, 10−7M) and (5) 17-β oestradiol (E2, 10−9M) for 24 h. After exposure, PGF2α and PGE2 concentrations were determined using direct enzyme immunoassays. Alterations in PG synthase mRNA expression were determined using RT-qPCR. After 24 h, LH and P4 increased PGE2 and PGF2α secretion by myometrial tissues at the mid-luteal phase (P