Elevated follicular fluid angiotensin II and pregnancy outcome

Trehalosemodulates OVRAS to improve oxidative stress and apoptosis in KGN cells and ovaries of PCOS mice

The etiology of polycystic ovary syndrome (PCOS) is complex and variable, and there is no exact cause or good treatment method. Most of the methods of hormones are used to temporarily meet the needs of patients. Experimental evidence has shown that trehalose has, anti-apoptotic, anti-oxidative, glucose-lowering, and insulin resistance effects. However, whether trehalose has a therapeutic effect on PCOS is unknown. It has been reported that the ovarian renin-angiotensin system (OVRAS) is involved in the development of PCOS, but it has not been fully elucidated. This study aims to explore the effect of trehalose on PCOS and elucidate the related OVRAS mechanism. We first observed that body weight, estrous cycle, ovarian follicles at all levels, glucose tolerance, serum hormones, and insulin resistance were improved by trehalose treatment in the PCOS mouse model. Moreover, trehalose treatment also ameliorated ovarian oxidative stress and apoptosis in PCOS mice, as determined by TUNNEL apoptosis staining, total SOD in ovarian homogenate, and WB assay. OVRAS mainly involves two classic pathways, namely the ACE/AngII/AT1R/AT2R, and ACE2 / Ang1-7/ MASR, Which play different functions. In PCOS mouse ovaries, we found that ACE/AngII/AT1R was up-regulated and ACE2/Ang1-7/MASR and AT2R were down-regulated by PCR and WB experiments, However, trehalose treatment changed its direction. In addition, we also found that trehalose ameliorated DHEA-induced oxidative stress and apoptosis in KGN by PCR and WB experiments, mainly by down-regulating ACE/AngII/AT1R. Our study shows that trehalose improves symptoms of PCOS mainly by down-regulating ACE/AngII/AT1R, revealing a potential therapeutic target for PCOS.

Progesterone-Induced Sperm Release from the Oviduct Sperm Reservoir

In mammalian females, after sperm are deposited in the reproductive tract, a fraction of sperm migrates to the lower oviduct (isthmus) and forms a sperm storage site known as the functional sperm reservoir. The interactions between sperm membrane proteins and oviduct epithelial cells facilitate sperm binding to the oviductal epithelium and retention in the reservoir. Sperm are bound by glycans that contain specific motifs present on isthmic epithelial cells. Capacitated sperm are released from the reservoir and travel further in the oviduct to the ampulla where fertilization occurs. For decades, researchers have been studying the molecules and mechanisms of sperm release from the oviductal sperm reservoir. However, it is still not clear if the release of sperm is triggered by changes in sperm, oviduct cells, oviduct fluid, or a combination of these. While there is a possibility that more than one of these events are involved in the release of sperm from the reservoir, one activator of sperm release has the largest accumulation of supporting evidence. This mechanism involves the steroid hormone, progesterone, as a signal that induces the release of sperm from the reservoir. This review gathers and synthesizes evidence for the role of progesterone in inducing sperm release from the oviduct functional sperm reservoir.

Localization of angiotensin-II type 1(AT1) receptors on buffalo spermatozoa: AT1 receptor activation during capacitation triggers rise in cyclic AMP and calcium

The purpose of this study was to determine the role of Ang-II in buffalo spermatozoa; localize angiotensin type 1 (AT1) receptors on the sperm surface and understand the signaling mechanisms involved therein. Immunoblotting and immunocytochemistry using polyclonal Rabbit anti-AT1 (N-10) IgG were performed to confirm the presence of AT1 receptors. Intracellular levels of cyclic adenosine monophosphate (cAMP) were determined by non-radioactive enzyme immunoassay, while that of Calcium [Ca(2+)] were estimated by fluorimetry using Fura2AM dye. The results obtained showed that AT1 receptors were found on the post-acrosomal region, neck and tail regions. Immunoblotting revealed a single protein band with molecular weight of 40 kDa. Ang-II treated cells produced significantly higher level of cAMP compared to untreated cells (22.66 ± 2.4 vs. 10.8 ± 0.98 pmol/10(8) cells, p < 0.01). The mean levels of Ca(2+) were also higher in Ang-II treated cells compared to control (117.4 ± 6.1 vs. 61.15 ± 4.2 nmol/10(8) cells; p < 0.01). The stimulatory effect of Ang-II in both the cases was significantly inhibited in the presence of Losartan (AT1 antagonist; p < 0.05) indicating the involvement of AT1 receptors. Further, presence of neomycin (protein kinase C inhibitor) inhibited significantly the Ang-II mediated rise in Ca(2+) indicating the involvement of PKC pathway. These findings confirm the presence of AT1 receptors in buffalo spermatozoa and that Ang-II mediates its actions via the activation of these receptors. Ang-II stimulates the rise in intracellular levels of cAMP and Ca(2+) during capacitation.

The classical progesterone receptor mediates the rapid reduction of fallopian tube ciliary beat frequency by progesterone

BACKGROUND

The transport of gametes as well as the zygote is facilitated by motile cilia lining the inside of the fallopian tube. Progesterone reduces the ciliary beat frequency within 30 minutes in both cows and mice. This rapid reduction suggest the involvement of a non-genomic signaling mechanism, although it is not known which receptors that are involved. Here we investigated the possible involvement of the classical progesterone receptor in this process.

METHOD

The ciliary beat frequency of mice fallopian tube was measured ex vivo using an inverted bright field microscope and a high speed camera. The effects of the agonists progesterone and promegestone and an antagonist, mifeprestone, were investigated in wildtype mice. The effect of progesterone was also investigated in mice lacking the classical progesterone receptor.

RESULTS

Progesterone, as well as the more specific PR agonist promegestone, significantly reduced the CBF at concentrations of 10-100 nanomolar within 10-30 minutes. In the absence of progesterone, the PR antagonist mifeprestone had no effect on the ciliary beat frequency at a concentration of 1 micromolar. When ciliated cells were pre-incubated with 1 micromolar mifeprestone, addition of progesterone did not reduce the ciliary beat frequency. Accordingly, in ciliated cells from mice not expressing the classical progesterone receptor, exposure to 100 nanomolar progesterone did not reduce the ciliary beat frequency.

CONCLUSIONS

This is the first study to provide comprehensive evidence that the classical progesterone receptor mediates the rapid reduction of the tubal ciliary beat frequency by progesterone.

Metabolite Profiling in the Pursuit of Biomarkers for IVF Outcome: The Case for Metabolomics Studies

Background. This paper presents the literature on biomarkers of in vitro fertilisation (IVF) outcome, demonstrating the progression of these studies towards metabolite profiling, specifically metabolomics. The need for more, and improved, metabolomics studies in the field of assisted conception is discussed. Methods. Searches were performed on ISI Web of Knowledge SM for literature associated with biomarkers of oocyte and embryo quality, and biomarkers of IVF outcome in embryo culture medium, follicular fluid (FF), and blood plasma in female mammals. Results. Metabolomics in the field of female reproduction is still in its infancy. Metabolomics investigations of embryo culture medium for embryo selection have been the most common, but only within the last five years. Only in 2012 has the first metabolomics investigation of FF for biomarkers of oocyte quality been reported. The only metabolomics studies of human blood plasma in this context have been aimed at identifying women with polycystic ovary syndrome (PCOS). Conclusions. Metabolomics is becoming more established in the field of assisted conception, but the studies performed so far have been preliminary and not all potential applications have yet been explored. With further improved metabolomics studies, the possibility of identifying a method for predicting IVF outcome may become a reality.

Bovine sperm acrosome reaction induced by G-protein-coupled receptor agonists is mediated by epidermal growth factor receptor transactivation

We have previously demonstrated the presence of active epidermal growth factor receptor (EGFR) and its involvement in sperm capacitation and the acrosome reaction; however, the mechanism of EGFR activation was not clear. We show here that the sperm EGFR can be transactivated by angiotensin II or by lysophosphatydic acid, two ligands which activate specific G-protein-coupled receptors (GPCR), or by directly activating protein kinase A using 8Br-cAMP. This transactivation occurs in noncapacitated sperm and is mediated by PKA, SRC and a metalloproteinase. We also show that the EGFR is activated in sperm incubated under in vitro capacitation conditions, without any added ligand, but not in bicarbonate-deficient medium or when PKA is blocked. Despite the fact that EGFR is activated in capacitated sperm, this state is not sufficient to induce the acrosome reaction. We conclude that the EGFR is stimulated during capacitation via PKA activation, while further activation of the EGFR in capacitated sperm is required in order to induce the acrosome reaction. The acrosome reaction can be induced by GPCR via the transactivation of the EGFR by a signaling pathway involving PKA, SRC and metalloproteinase and the EGFR down-stream effectors PI3K, PLC and PKC.

Follicular fluid content and oocyte quality: from single biochemical markers to metabolomics

The assessment of oocyte quality in human in vitro fertilization (IVF) is getting increasing attention from embryologists. Oocyte selection and the identification of the best oocytes, in fact, would help to limit embryo overproduction and to improve the results of oocyte cryostorage programs. Follicular fluid (FF) is easily available during oocyte pick-up and theorically represents an optimal source on non-invasive biochemical predictors of oocyte quality. Unfortunately, however, the studies aiming to find a good molecular predictor of oocyte quality in FF were not able to identify substances that could be used as reliable markers of oocyte competence to fertilization, embryo development and pregnancy. In the last years, a well definite trend toward passing from the research of single molecular markers to more complex techniques that study all metabolites of FF has been observed. The metabolomic approach is a powerful tool to study biochemical predictors of oocyte quality in FF, but its application in this area is still at the beginning. This review provides an overview of the current knowledge about the biochemical predictors of oocyte quality in FF, describing both the results coming from studies on single biochemical markers and those deriving from the most recent studies of metabolomics.

Effect of angiotensin converting enzyme (ACE) and angiotensins on human sperm functions

The presence of components of the renin angiotensin system (RAS) and specific receptors of angiotensin II in the female and male reproductive tract supports the hypothesis that reproductive functions may be controlled by RAS. Therefore, the present study investigated the influence of ACE and angiotensins on sperm functions and the sperm-egg interaction. The experiments did not indicate direct effects of ACE on the capacitation process or acrosome reaction. Release of ACE from human spermatozoa during capacitation was not related to their ability to undergo acrosome reaction after stimulation with ionophore. Therefore, ACE release does not seem to be a useful clinical marker for human sperm capacitation. However, decreased binding of human spermatozoa to the oolemma of zonafree hamster oocytes after inhibition of ACE by captopril indicates that kininase II is involved in sperm-egg interactions. In contrast to other studies, incubation with captopril had no influence on sperm binding to the zona pellucida. Because effects of ACE on sperm-egg interactions but not on capacitation or acrosome reaction were observed, several experiments were performed to study the influence of substrates and products on the acrosome reaction. Angiotensin II induced the acrosome reaction dose-dependently, whereas angiotensin I had no effect on the acrosome reaction. The effect of angiotensin II on acrosome reaction seems to be calcium-dependent and mediated by protein kinases. Since a specific type 2 angiotensin II receptor inhibits the acrosome reaction induced by angiotensin II, this subtype of receptors may be present at the surface of sperm heads. Another clue for the presence of type 2 receptors on human spermatozoa is the finding that pertussis toxin did not inhibit the angiotensin II induced acrosome reaction. In contrast to type 1 angiotensin II receptors, type 2 receptors are known to be G-protein independent.

Angiotensin II induces acrosomal exocytosis in bovine spermatozoa

Ejaculated mammalian spermatozoa must reside in the female genital tract for some time before gaining the ability to fertilize the egg. During this time, spermatozoa undergo some physiological changes that collectively are called capacitation. Capacitation of mammalian spermatozoa is a prerequisite for acrosome reaction, which is an exocytotic event occurring before fertilization. The specific biophysical and biochemical changes that accompany sperm capacitation and the agonists inducing acrosome reaction are not fully understood. Using SDS-gel electrophoresis and immunoblotting, we demonstrate the existence of a class of angiotensin receptors (AT1) in bovine spermatozoa. In capacitated sperm, we show that angiotensin II (ANG II) AT1 receptors are localized in the head and tail, whereas in noncapacitated cells the receptors are localized in the tail only. We find that ANG II markedly stimulates acrosomal exocytosis of capacitated bovine spermatozoa in vitro in a concentration range of 0.1-10 nM. No effect of ANG II was found in noncapacitated cells. The ability of ANG II to stimulate the acrosome reaction depends on the presence of calcium ions in the incubation medium. The ANG II-induced acrosome reaction was markedly inhibited by a selective AT1 receptor antagonist, losartan (DUP 753). PD-123319, a selective antagonist of the ANG II AT2 receptor, had no effect on the ANG II-induced acrosome reaction. Thus ANG II via activation of AT1 receptors may play a regulatory role in the induction of the acrosome reaction.