Regulatory changes of local produced prostaglandins in corpus luteum after experimentally induced luteolysis in the cow.

Abstract

The objective of the study was to evaluate the expression patterns of prostaglandin F2alpha (PGF), prostaglandin E2 (PGE), PGF receptor (FP), PGE receptors (EP2 and EP4), prostaglandin-endoperoxide synthase 2 (PTGS2) and prostaglandin synthases (PGFS and PGES) in corpora lutea (CL) during experimentally induced luteolysis in cow. The Fleckvieh cows in the mid-luteal phase (days 8-12, control group) were injected with cloprostenol (PGF analogue), and CL were collected by transvaginal ovariectomy before (days 8-12, control group) and at 0.5, 2, 4, 12, 24, 48 and 64h after PGF application (n=5 per group). The mRNA expression was determined by RT-qPCR, the hormone concentrations by enzyme immunoassay and localization by immunohistochemistry. PTGS2gene expression increased significantly 2h after PGF application, followed by continuous and significant downregulation afterwards. The PGF tissue concentration increased significantly just after PGF injection and again during structural luteolysis (after 12h), whereas PGE concentration significantly decreased during structural luteolysis. The FP receptor mRNA decreased significantly at 2h and again at 12h after PGF. In contrast, EP4 receptor mRNA increased significantly just after the PGF application (0.5h). The immunostaining of PGES and PTGS2 on day 15-17shows numerous positive luteal cells, followed by lower activity afterwards on day 18 (luteolysis). In conclusion, the changes of examined prostaglandin family members in CL tissue after PGF application may be key components of the local mechanisms regulating the cascade of actions leading to functional and subsequent structural luteolysis in the bovine ovary.