Senescence in placental cells impacts physiological functions and contributes to pathology. Therefore, we examined biochemical markers of cellular senescence—p38, P-p38, p21, and p53—during pregnancy, at parturition, and in cases of retained fetal membranes. Placentomes were collected from pregnant cows (2nd, 4th, and 5th months of gestation) and parturient cows undergoing cesarean section, categorized as NR or RFM. Samples were separated into maternal and fetal parts and analyzed via WB and ELISA. WB confirmed protein presence, while ELISA showed a significant increase in the concentrations of both p38 and P-p38 in the fetal part in the 5th month of gestation as compared to earlier months. No significant differences were observed in the maternal part across pregnancy and parturition. These findings suggest p38 and P-p38 may be important molecules regulating the normal development of the bovine placenta during middle pregnancy. Further studies are needed to elucidate the mechanisms of their action.

Post-translational modifications (phosphorylation and glutathionylation) not only assure protein diversity but are also responsible for the controlling of the biological activity of selected proteins in health and disease. The aim of the study was to monitor the profile of changes in molecular weight of proteins undergoing selected post-translational modifications by measurement of the intensity of phosphorylation and glutathionylation within the pregnancy course and parturition in cows with and without the retention of foetal membranes. The intensity of selected post-translational modifications was measured in bovine placental tissues collected during pregnancy (2nd, 4th, 5th, and 7th month, n = 4 per month) and parturition (not-retained foetal membranes (NRFM, n = 6) and retained foetal membranes (RFM, n = 6). Placental tissues were homogenised and used for the Phosphoprotein Phosphate Estimation Assay Kit and Western blotting analyses with adequate antibodies. The content of phosphorylated proteins was significantly higher (p < 0.05) in the 2nd month as compared to other months, both in the maternal and foetal parts of the placenta. Moreover, no significant differences were observed between NRFM and RFM samples. The results of Western blotting showed the shift in molecular weight and indirect content of phosphorylated selected amino acids. Further research on the role of post-translational modifications in pregnancy and parturition may give new insight into their biochemical regulation.

The placenta is indispensable for the maintenance of pregnancy. It is responsible for the metabolism of the foetus and the mother and their connection. The enzymes that catalyse the metabolic reactions involved not only in biochemical pathways but also in the synthesis and breakdown of biologically active substances are widely distributed in placental cells and tissues. Their presence assures the physiological course of pregnancy and changes in their activity may cause pregnancy disorders. The present review summarizes the knowledge on the enzymes in the bovine placenta, shedding light on their multifaceted functions and importance. It focuses on enzymes with a key role in antioxidant defence mechanisms, protecting both the foetus and the mother from the harmful effects of free radicals, on enzymes involved in the synthesis of sex steroids, a key aspect of hormonal regulation during pregnancy, and on enzymes responsible for prostaglandin metabolism that affect various physiological processes. It also defines the enzymes involved in the metabolism of connective tissue, which contribute to the structural integrity of this important organ and ensure its continued functionality throughout pregnancy. Finally, it provides information on enzymes related to DNA damage and on indicatory enzymes. By presenting placental enzymes, we hope to provide insights into the biochemical processes that underlie the maintenance of a healthy pregnancy and placental development and maturation and to describe the potential implications of problems with the enzymes, e.g. the retention of foetal membranes (RFM).