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 64 h 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. PTGS2 gene expression increased significantly 2 h 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 12 h), whereas PGE concentration significantly decreased during structural luteolysis. The FP receptor mRNA decreased significantly at 2 h and again at 12 h after PGF. In contrast, EP4 receptor mRNA increased significantly just after the PGF application (0.5 h). The immunostaining of PGES and PTGS2 on day 15–17 shows 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.

Prostaglandins as local regulators of ovarian physiology in ruminants

“…In a F I G U R E 2 Schematic presentation of concentration profile of prostaglandin F2 alpha (PGF) and prostaglandin E2 (PGE) in corpus luteum (CL) classes during oestrous cycle at days: 1-2, 3-4, 5-7, 8-12, 13-17 and >18 (after luteolysis) in the cow (adapted from Berisha et al, 2018). previously published experimental paper, we documented specific expression patterns of prostaglandin system members (responsible enzymes, ligands and their receptors) in CL groups collected before and after PGF injection in cows (Berisha et al, 2022). The increase in PGF concentration (Figure 3) immediately after the start of luteolysis (after 2 h) correlates well with the enzyme responsible for its production (PGFS) and with the increased expression of its specific receptor (PGFR), documented before (Berisha et al, 2022).…”

“…Among the prostaglandin receptors studied in ovarian tissue, the PGE receptors (specifically EP2 and EP4) signal through Gs-mediated increases in cAMP (cyclic adenosine 3′,5′-monophosphate), whereas the PGF receptor (FP) signals through Gq-mediated increases in intracellular calcium, mechanisms which then activate ovarian cells to stimulate the induction of specific genes related to different functions of the ovary (Cha et al, 2006;Chen et al, 2001;Davis et al, 1987;Hatae et al, 2002). Because PGE and PGF have different actions, multiple signalling pathways are involved in the regulation of various endocrine-paracrine factors (chemokine and cytokine) that could lead to local modulation of the final biological actions (Berisha et al, 2022;Plewes et al, 2023;Xu et al, 2015).…”

“…Recognizing the undoubted importance of above-mentioned mediators in reproduction processes, our research group focused on the main phases of ovarian function, using different experimental models and analytical methods (Berisha et al, 2019(Berisha et al, , 2020(Berisha et al, , 2022Livak & Schmittgen, 2001;Mueller et al, 2004).…”

“…Prostaglandins, and other endocrine and intraluteal factors discussed in this study also regulate the luteal regression process (luteolysis), the necessary functional phase of the CL, that enables the beginning of the next oestrous cycle. concentration profile of prostaglandin F2 alpha (PGF) and prostaglandin E2 (PGE) in corpus luteum (CL) classes after experimentally induced luteolysis (hours): 0, 0.5, 2, 4, 12, 24, 48 and 64 h in the cow (adapted from Berisha et al, 2022).…”

“…Here, we can mention the essential role of prostaglandins during the ovarian cycle, endometrial receptivity, embryo implantation, pregnancy, parturition and postpartum stage (Weems et al, 2006). Recognizing the undoubted importance of above‐mentioned mediators in reproduction processes, our research group focused on the main phases of ovarian function, using different experimental models and analytical methods (Berisha et al, 2019, 2020, 2022; Livak & Schmittgen, 2001; Mueller et al, 2004).…”