Ilona Kowalczyk-Zieba

Diverse Effects of Phytoestrogens on the Reproductive Performance: Cow as a Model

Phytoestrogens, polyphenolic compounds derived from plants, are more and more common constituents of human and animal diets. In most of the cases, these chemicals are much less potent than endogenous estrogens but exert their biological effects via similar mechanisms of action. The most common source of phytoestrogen exposure to humans as well as ruminants is soybean-derived foods that are rich in the isoflavones genistein and daidzein being metabolized in the digestive tract to even more potent metabolites—para-ethyl-phenol and equol. Phytoestrogens have recently come into considerable interest due to the increasing information on their adverse effects in human and animal reproduction, increasing the number of people substituting animal proteins with plant-derived proteins. Finally, the soybean becomes the main source of protein in animal fodder because of an absolute prohibition of bone meal use for animal feeding in 1995 in Europe. The review describes how exposure of soybean-derived phytoestrogens can have adverse effects on reproductive performance in female adults.

The effect of lysophosphatidic acid during in vitro maturation of bovine cumulus–oocyte complexes: cumulus expansion, glucose metabolism and expression of genes involved in the ovulatory cascade, oocyte and blastocyst competence

BackgroundIn the cow, lysophosphatidic acid (LPA) acts as an auto-/paracrine factor, through its receptors LPAR1-4, on oocytes and cumulus cells during in vitro maturation (IVM). The aim of the present work was to determine the effect of LPA during IVM of bovine oocytes on: 1) oocyte maturation; 2) apoptosis of COCs; 3) expression of genes involved in developmental competence and apoptosis in bovine oocytes and subsequent blastocysts; 4) cumulus expansion and expression of genes involved in the ovulatory cascade in cumulus cells; 5) glucose metabolism and expression of genes involved in glucose utilization in cumulus cells; 6) cleavage and blastocyst rates on Day 2 and Day 7 of in vitro culture, respectively.MethodsCumulus-oocyte complexes (COCs) were matured in vitro in the presence or absence of LPA (10−5M) for 24h. Following maturation, we determined: oocyte maturation stage, cumulus expansion, COCs apoptosis and glucose and lactate levels in the maturation medium. Moreover, COCs were either used for gene expression analysis or fertilized in vitro. The embryos were cultured until Day 7 to assess cleavage and blastocyst rates. Oocytes, cumulus cells and blastocysts were used for gene expression analysis.ResultsSupplementation of the maturation medium with LPA enhanced oocyte maturation rates and stimulated the expression of developmental competence-related factors (OCT4, SOX2, IGF2R) in oocytes and subsequent blastocysts. Moreover, LPA reduced the occurrence of apoptosis in COCs and promoted an antiapoptotic balance in the transcription of genes involved in apoptosis (BAX and BCL2) either in oocytes or blastocysts. LPA increased glucose uptake by COCs via augmentation of GLUT1 expression in cumulus cells as well as stimulating lactate production via the enhancement of PFKP expression in cumulus cells. LPA did not affect cumulus expansion as visually assessed, however, it stimulated upstream genes of cumulus expansion cascade, AREG and EREG.ConclusionsSupplementation of the maturation medium with LPA improves oocyte maturation rates, decreases extent of apoptosis in COCs and sustains the expression of developmental competence related factors during oocyte maturation and subsequently affects gene expression profile at the blastocyst stage. We also demonstrate that LPA directs glucose metabolism toward the glycolytic pathway during IVM.

Lysophosphatidic Acid Signaling in Late Cleavage and Blastocyst Stage Bovine Embryos

Lysophosphatidic acid (LPA) is a known cell signaling lipid mediator in reproductive tissues. In the cow, LPA is involved in luteal and early pregnancy maintenance. Here, we evaluated the presence and role of LPA in bovine early embryonic development. In relevant aspects, bovine embryos reflect more closely the scenario occurring in human embryos than the mouse model. Transcription of mRNA and protein expression of enzymes involved in LPA synthesis (ATX and cPLA2) and of LPA receptors (LPAR1–4) were detected in Days 5 and 8 in vitro produced embryos. Embryonic LPA production into culture medium was also detected at both stages of development. Supplementation of culture medium with LPA (10−5 M) between Days 2 and 8 had no effect on embryo yield and quality and on blastocyst relative mRNA abundance of genes involved in prostaglandin synthesis (PTGS2, PGES, and PGFS) and steroidogenesis (3β HSD). However, LPA treatment affected transcription levels of embryo quality markers, decreasing BAX (apoptotic) and increasing BCL2 (antiapoptotic) and IGF2R (growth marker) gene transcription levels. Blastocyst transcription of OCT4 (pluripotency marker) was not affected by LPA stimulation. In conclusion, LPA is an early bovine embryonic autocrine/paracrine signaling mediator, and LPA action may be relevant in early embryo-maternal interactions leading to embryonic survival.

The Effect of Lysophosphatidic Acid during In Vitro Maturation of Bovine Oocytes: Embryonic Development and mRNA Abundances of Genes Involved in Apoptosis and Oocyte Competence

In the present study we examined whether LPA can be synthesized and act during in vitro maturation of bovine cumulus oocyte complexes (COCs). We found transcription of genes coding for enzymes of LPA synthesis pathway (ATX and PLA2) and of LPA receptors (LPAR 1–4) in bovine oocytes and cumulus cells, following in vitro maturation. COCs were matured in vitro in presence or absence of LPA (10−5 M) for 24 h. Supplementation of maturation medium with LPA increased mRNA abundance of FST and GDF9 in oocytes and decreased mRNA abundance of CTSs in cumulus cells. Additionally, oocytes stimulated with LPA had higher transcription levels of BCL2 and lower transcription levels of BAX resulting in the significantly lower BAX/BCL2 ratio. Blastocyst rates on day 7 were similar in the control and the LPA-stimulated COCs. Our study demonstrates for the first time that bovine COCs are a potential source and target of LPA action. We postulate that LPA exerts an autocrine and/or paracrine signaling, through several LPARs, between the oocyte and cumulus cells. LPA supplementation of maturation medium improves COC quality, and although this was not translated into an enhanced in vitro development until the blastocyst stage, improved oocyte competence may be relevant for subsequent in vivo survival.

Influence of lysophosphatidic acid on estradiol production and follicle stimulating hormone action in bovine granulosa cells.

The objective of the study was to examine the effect of lysophosphatidic acid (LPA) on 17β-estradiol (E2) synthesis and follicle stimulating hormone (FSH) action in bovine granulosa cells. We found that granulosa cells in the bovine antral follicle, in addition to the uterus and the CL, are also the site of LPA synthesis and the target for LPA action in the bovine reproductive tract. Our findings suggest that LPA stimulates E2 synthesis, probably via increased expression of FSHR and 17β-HSD genes.

Which bovine endometrial cells are the source of and target for lysophosphatidic acid

The objective of the study was to examine which cultured endometrial cells are the source and which are the target for lysophosphatidic acid (LPA) in the bovine uterus. LPA concentration as well as mRNA and protein expressions of the enzymes responsible for LPA synthesis (phospholipase A2: PLA2, autotaxin: AX) were greater in epithelial than in stromal cells (P<0.05). In turn, mRNA and protein expression of LPA receptor (LPAR1) was lower in epithelial than in stromal cells (P<0.05). We suggest that LPA in bovine endometrium is produced mainly by epithelial cells and affects mostly stromal cells acting via LPAR1.

Lysophosphatidic Acid (LPA) Signaling in Human and Ruminant Reproductive Tract

Lysophosphatidic acid (LPA) through activating its G protein-coupled receptors (LPAR 1–6) exerts diverse cellular effects that in turn influence several physiological processes including reproductive function of the female. Studies in various species of animals and also in humans have identified important roles for the receptor-mediated LPA signaling in multiple aspects of human and animal reproductive tract function. These aspects range from ovarian and uterine function, estrous cycle regulation, early embryo development, embryo implantation, decidualization to pregnancy maintenance and parturition. LPA signaling can also have pathological consequences, influencing aspects of endometriosis and reproductive tissue associated tumors. The review describes recent progress in LPA signaling research relevant to human and ruminant reproduction, pointing at the cow as a relevant model to study LPA influence on the human reproductive performance.

Lysophosphatidic acid expression in theca cells depends on the type of bovine ovarian follicle

Lysophosphatidic acid (LPA) exerts various actions on the mammalian reproductive system. In cows, LPA stimulates the synthesis and secretion of luteotropic factors in the ovary, which affects the growth and development of ovarian follicles. The role of LPA in granulosa cells, oocyte and oocyte-cumulus complex (COC) has previously been investigated; but its role in the theca layer, which is an important structural and functional component of the ovarian follicle, is still unclear. The goal of this study was to investigate the expression of LPA in theca cells originating from different bovine ovarian follicle types. Theca cells were separated from healthy, transitional and atretic ovarian follicles, based on intrafollicular estradiol: progesterone ratios. LPA concentration in the follicular fluid (FF) in different follicle types was measured, and expression of the enzymes responsible for LPA synthesis (autotaxin [AX], phospholipase A2 [PLA2]) and receptors for LPA (LPAR1-4) were determined. The obtained results confirmed the follicle-type dependent presence of LPA in the FF of the bovine ovarian follicles. The highest concentration of LPA was detected in follicles classified as healthy and dominant. LPAR1-4, PLA2 and AX expression in theca cells in all of the types of follicles examined were detected at mRNA and protein level. These results suggest that theca cells can be a source of LPA synthesis other than granulosa cells and COCs, as well as the target for its action in the bovine ovarian follicle, with PLA2 and LPAR4 playing major roles in LPA synthesis and action.

Influence of Lysophosphatidic Acid on Nitric Oxide-Induced Luteolysis in Steroidogenic Luteal Cells in Cows

ABSTRACT Lysophosphatidic acid (LPA) together with its active G protein-coupled receptors are present in the corpus luteum (CL) of the cow. Under in vivo conditions, LPA stimulated P4 and PGE2 secretion during the luteal phase of the estrous cycle in heifers. Furthermore, LPA maintained P4 synthesis and actions in the bovine CL in vitro. However, the effect of this phospholipid on nitric oxide (NO)-induced functional and structural luteolysis has not been investigated. The aim of the present work was to determine the effects of LPA on 1) NO-induced functional luteolysis, 2) NO-dependent PG synthesis, and 3) NO-induced structural luteolysis in cultured steroidogenic luteal cells. We documented that LPA reversed the inhibitory effect of NONOate, an NO donor, on P4 synthesis and PGE2/PGF2alpha ratio in cultured steroidogenic luteal cells. Additionally, LPA inhibited NO-induced apoptosis in cultured steroidogenic luteal cells via abrogation of the NO-dependent stimulatory influence on proapoptotic TNFalpha/TNFR1 and Fas/FasL expression, Caspase 3 activity, and the Bax/Bcl2 ratio during luteal regression in the bovine CL. In conclusion, this study proves that in the presence of LPA, NO cannot induce luteolytic capacity acquisition, leading to functional and structural luteolysis of bovine luteal cells.

Effects of lysophopatidic acid on tumor necrosis factor α and interferon γ action in the bovine corpus luteum.

We examined the effects of LPA on TNFα and IFNγ - induced decrease of P4 synthesis and on the cytokine - induced apoptosis of the cultured luteal cells. In the steroidogenic luteal cells LPA reversed the inhibitory effect of TNFα and IFNγ on P4 synthesis and also inhibited the stimulatory effects of TNFα and IFNγ on the expression of Bax, TNFR1, Fas and FasL as well as caspase 3 activity. These results suggest that TNFα and IFNγ cannot induce apoptosis in the presence of LPA, which orientates the steroidogenic luteal cells towards the survival state. In conclusion our results indicate that LPA supports P4 synthesis and action in the bovine CL.