The Role of Peroxisome Proliferator-Activated Receptors in PGF2α-Induced Luteolysis in the Bovine Corpus Luteum

Abstract

The participation of peroxisome proliferator-activated receptors (PPARs) in ovarian function in cattle is still not fully understood. The aim of this in vitro study was to determine: (i) the immunolocalization, mRNA expression and tissue concentration of PPARα, PPARδ and PPARγ in the bovine corpus luteum (CL) (n = 40) throughout the estrous cycle, and (ii) the involvement of PPAR in PGF2α-induced processes related to luteolysis. CL (n = 9) explants were cultured in the presence of PPAR antagonists (10−5 M) in combination with or without PGF2α receptor antagonist (10−5 M) and PGF2α (10−6 M). The mRNA and protein expression of PPARs was evaluated through qPCR, IHC, and ELISA, respectively. The results showed that PPAR mRNA and protein expression differed according to the luteal stages. PGF2α upregulated PPARδ and PPARγ mRNA expression in the bovine CL in vitro, whereas PPARγ increased the inhibitory effect of PGF2α by decreasing progesterone secretion and the mRNA expression of hydroxy-delta-5-steroid dehydrogenase, 3 β- and steroid delta-isomerase 1 (HSD3B1) in the CL explants; mRNA transcription of tumor necrosis factor α (TNFα) and inducible nitric oxide synthase (iNOS) was increased. The obtained results indicate that the mRNA and protein expression of PPARs changes in the bovine CL throughout the estrous cycle and under the influence of PGF2α. We suggest that isoform γ, among all examined PPARs, could be a factor involved in the regulation of PGF2α-induced processes related to luteolysis in the bovine CL. Further studies are needed to understand the role of PPAR in luteal regression in the CL of cattle.

Local Expression Dynamics of Various Adipokines during Induced Luteal Regression (Luteolysis) in the Bovine Corpus Luteum

“…Moreover, CL regression also includes the activation of various apoptotic pathways within the CL and a decrease in blood supply to the CL as a result of both vasoconstriction due to PGF2α and changes in the expression of local growth factors like angiogenic, luteolytic, and extracellular matrix remodeling factors [21,[48][49][50]. These gene expression changes are responsible for reducing P4 levels and increasing pro-apoptotic gene activity.…”

Nitric oxide synthase and its function in animal reproduction: an update

“…However, in canines, expression of eNOS and iNOS was lowest on the day of ovulation, whereas eNOS expression increased significantly towards day 20. On days 20 and 30, iNOS, endothelins exerted their vascular endothelin A receptor-and endothelin receptor B during CL rapid development-mediated effects and then activate the nitric oxide (NO) pathway (Tavares Pereira et al, 2019;Socha et al, 2022). Exogenous melatonin increased the CL diameter and colored area, accompanied by decreased NO from the serum until days 6 and 14, which may be involved in activating eNOS in heat-stressed cows (Kantar et al, 2015;Abdelnaby and Abo El-Matty, 2021).…”

Prostaglandins as local regulators of ovarian physiology in ruminants

“…Decreased progesterone levels during the luteolysis process result in the apoptotic demise of luteal cells (Rueda et al, 2000; Socha et al, 2022). This phenomenon exhibits variations in different species (Sugino & Okuda, 2007).…”