Roles for prostaglandins in the steroidogenic response of human granulosa cells to high-density lipoproteins

Seasonal expressions of COX-1, COX-2, and EP4 in the scent glands of muskrats (Ondatra zibethicus)

Prostaglandins (PGs) serve as signaling molecules that regulate various physiological processes, including inflammation, immune response, blood clotting, and reproduction. The aim of this study was to investigate the immunolocalizations and expression patterns of prostaglandin-E2 (PGE2), cyclooxygenase (COX)-1, and COX-2, as well as its receptor subtypes 4 (EP4) in the scent glands of muskrats (Ondatra zibethicus) during the breeding and nonbreeding periods. There were significant seasonal differences in the scent glandular mass, with higher values in the breeding season and relatively low in the nonbreeding season. PGE2, EP4, COX-1, and COX-2 have been immunolocalized in the scent glandular and epithelial cells in both breeding and nonbreeding seasons, whereas no immunostaining was observed in the interstitial cells. The protein and mRNA expression levels of EP4, COX-1, and COX-2 were higher in the scent glands of the breeding season than those of the nonbreeding season. The mean mRNA levels of EP4, COX-1, and COX-2 were positively correlated with the scent glandular weights. The circulating follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T), and PGE2, as well as scent glandular PGE2 and dihydrotestosterone (DHT) concentrations, were also significantly higher in the breeding season. In addition, the transcriptomic study in the scent glands identified that differentially expressed genes might be related to fatty carboxylic monocarboxylic acid, steroidogenic-related pathways, and prostanoid metabolic processes. These findings suggested that prostaglandin-E2 might play an essential autocrine or paracrine role in regulating seasonal changes in the scent glandular functions of the muskrats.

Untargeted foodomics reveals molecular mechanism of magnetic field effect on Feng-flavor Baijiu ageing

Ageing is a time-consuming step in Baijiu manufacture, stimulating an urgent requirement of optimization. Variation of artificial aged Feng-flavor Baijiu by inhomogeneous alternating magnetic field was investigated through quantitative foodomics combined with confirmed ultra high performance liquid chromatography quadrupole-orbitaltrap high resolution mass spectrometry (UHPLC-Q-Orbitrap). A total of 153 substances were identified with significant variables (p < 0.05, VIP > 1) and 16 metabolic pathways related to Feng-flavor Baijiu functions were obtained. The method showed good accuracy with recovery values between 80.4% and 117.4% and precision lower than 9.8% for all characteristic substances. Limit of detection (LOD) was ranging between 1.6 and 10.0 μg/L with R² ≥ 0.99. Factor analysis demonstrated that ageing degree of magnetized samples increased with rise of magnetic field intensity and the maximum effect was equivalent to 12.81 years of natural ageing. The results of stoichiometric analysis revealed that regulation of magnetic field on proportion in Baijiu was mainly performed through entropy and the hydrogen bond strength of Baijiu molecules. Sensory evaluation illustrated that score of Baijiu samples reached the highest at 150 mT, demonstrating that magnetic field treatment can be considered as an optimized ageing means for Feng-flavor Baijiu.

17β-Estradiol is critical for the preovulatory induction of prostaglandin E(2) synthesis in mice

Aromatase-deficient (ArKO) mice are totally anovulatory due to insufficient estrogen production. However, sequential administrations of high doses of 17β-estradiol (E2) and gonadotropins were found to induce ovulation in these mice. Here, we examined how the ovulatory stimulation for ArKO mice alters the expressions of genes related to prostaglandin (PG) E(2) metabolism and ovarian contents of PGE(2), as PGE(2) is one of the critical mediators of ovulatory induction. The ovulatory stimulation significantly increased mRNA expressions of prostaglandin-endoperoxide synthase 2, PGE(2) receptor type 4 and sulfotransferase family 1E, member 1, in preovulatory ArKO ovaries. In contrast, it suppressed the mRNA expression of 15-hydroxyprostaglandin dehydrogenase. Furthermore, significant elevation in the PGE(2) contents was detected in the preovulatory ovaries of ArKO mice after stimulation with E2 plus ovulatory doses of gonadotropins. Thus, these analyses demonstrate a requirement of E2 for the preovulatory enhancement of PGE(2) synthesis, leading to future success in ovulation.

Effects of omega-3 and -6 polyunsaturated fatty acids on ovine follicular cell steroidogenesis, embryo development and molecular markers of fatty acid metabolism

We previously reported increased follicular fluid progesterone (P(4)) concentrations in ewes fed an n-3 compared to an n-6 polyunsaturated fatty acid (PUFA)-enriched diet, but detected no differential effect of n-3 and n-6 PUFA-enriched high-density lipoproteins (HDL) on granulosa cell (GC) steroidogenesis in vitro. Moreover, net n-6 PUFA-enriched HDL reduced early embryo development, but in the absence of a net uptake of FA. Consequently, we hypothesised that a) effects of n-3 PUFA on ovarian steroidogenesis are mediated by theca rather than GCs and b) during embryo culture lipids are acquired solely from the albumin fraction of serum, so that albumin-delivered n-3 and n-6 PUFA exert a greater differential effect on embryo development than either low-density lipoprotein (LDL)- or HDL-delivered PUFA. Data confirmed that n-3 PUFA increases P(4) production solely in theca cells and that this is associated with an increase in STAR transcript expression. Furthermore, LDL- and HDL-delivered n-3 PUFA are equally efficacious in this regard during the first 96 h of culture, but thereafter only HDL-delivered n-3 PUFA induces this effect in partially luteinised theca cells. We also demonstrate that albumin is the sole serum fraction that leads to a net uptake of FA during embryo culture. PUFA-enriched serum and albumin increased the yield of morphologically poorer quality blastocysts with increased transcript expression for the antioxidant enzyme SOD1. Important differential effects of n-3 and n-6 PUFA on ovarian steroidogenesis acting solely on theca cells are identified, but differential effects of PUFA on embryo development are less apparent.

Follicular fluid high-density lipoprotein-associated sphingosine 1-phosphate (S1P) promotes human granulosa lutein cell migration via S1P receptor type 3 and small G-protein RAC1

Coordinated migration and progesterone production by granulosa cells is critical to the development of the corpus luteum, but the underlying mechanisms remain obscure. Sphingosine 1-phosphate (S1P), which is associated with follicular fluid high-density lipoprotein (FF-HDL), was previously shown to regulate ovarian angiogenesis. We herein examined the effects of S1P and FF-HDL on the function of granulosa lutein cells. Both FF-HDL and S1P induced migration of primary human granulosa lutein cells (hGCs) and the granulosa lutein cell line HGL5. In addition, FF-HDL but not S1P promoted progesterone synthesis, and neither of the two compounds stimulated proliferation of granulosa lutein cells. Polymerase chain reaction and Western blot experiments demonstrated the expression of S1P receptor type 1 (S1PR1), S1PR2, S1PR3, and S1PR5 but not S1PR4 in hGCs and HGL5 cells. The FF-HDL- and S1P-induced granulosa lutein cell migration was emulated by FTY720, an agonist of S1PR1, S1PR3, S1PR4, and S1PR5, and by VPC24191, an agonist of S1PR1 and S1PR3, but not by SEW2871 and phytosphingosine 1-phosphate, agonists of S1PR1 and S1PR4, respectively. In addition, blockade of S1PR3 with CAY1044, suramine, or pertussis toxin inhibited hGC and HGL5 cell migration toward FF-HDL or S1P, while blockade of S1PR1 and S1PR2 with W146 and JTE013, respectively, had no effect. Both FF-HDL and S1P triggered activation of small G-protein RAC1 and actin polymerization in granulosa cells, and RAC1 inhibition with Clostridium difficile toxin B or NSC23766 abolished FF-HDL- and S1P-induced migration. The FF-HDL-associated S1P promotes granulosa lutein cell migration via S1PR3 and RAC1 activation. This may represent a novel mechanism contributing to the development of the corpus luteum.

Molecular mechanisms of ovulation: co-ordination through the cumulus complex

Successful ovulation requires that developmentally competent oocytes are released with appropriate timing from the ovarian follicle. Somatic cells of the follicle sense the ovulatory stimulus and guide resumption of meiosis and release of the oocyte, as well as structural remodelling and luteinization of the follicle. Complex intercellular communication co-ordinates critical stages of oocyte maturation and links this process with release from the follicle. To achieve these outcomes, ovulation is controlled through multiple inputs, including endocrine hormones, immune and metabolic signals, as well as intrafollicular paracrine factors from the theca, mural and cumulus granulosa cells and the oocyte itself. This review focuses on the recent advances in understanding of molecular mechanisms that commence after the gonadotrophin surge and culminate with release of the oocyte. These mechanisms include intracellular signalling, gene regulation and remodelling of tissue structure in each of the distinct ovarian compartments. Most critical ovulatory mediators exert effects through the cumulus cell complex that surrounds and connects with the oocyte. The convergence of ovulatory signals through the cumulus complex co-ordinates the key mechanistic processes that mediate and control oocyte maturation and ovulation.

Follicular fluid high density lipoprotein-associated sphingosine 1-phosphate is a novel mediator of ovarian angiogenesis

Angiogenesis plays an important role in the development of the ovarian follicle and its subsequent transition into the corpus luteum. Accordingly, follicular fluid is a rich source of mitogenic and angiogenic factors such as basic fibroblast growth factor and vascular endothelial growth factor secreted by granulosa cells. In the present study, we show that follicular fluid deprived of basic fibroblast growth factor or vascular endothelial growth factor by means of thermal denaturation or antibody neutralization retains its capacity to stimulate endothelial proliferation and angiogenesis. Mass spectrometric analysis of chromatographic fractions stimulating endothelial growth obtained from follicular fluid revealed that the heat-stable mitogenic activity is identical with the subfraction alpha of high density lipoproteins purified from follicular fluid (FF-HDL). Further investigations demonstrated that sphingosine 1-phosphate (S1P), one of the lysophospholipids associated with HDL, accounts for the capacity of this lipoprotein to stimulate endothelial growth and the formation of new vessels. Activation of mitogen-activated protein kinase (p42/44(ERK1/2)), protein kinase C, and protein kinase Akt represent signaling pathways utilized by FF-HDL and S1P to induce endothelial proliferation and angiogenesis. We conclude that FF-HDL represents a novel mitogenic and angiogenic factor present in follicular fluid and that S1P is one of the FF-HDL lipid components accounting for this activity.