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Exposure of mouse oocytes to saturated fatty acids (FAs) such as palmitic acid (PA) has been shown to increase lipid content and cause an endoplasmic reticulum (ER) stress response and changes in the mitochondrial redox state. PA can also disrupt Ca²⁺ stores in other cell types. The links between these intracellular changes, or whether they are prevented by mono-unsaturated FAs such as oleic acid (OA), is unclear. Here, we have investigated the effects of FAs on mouse oocytes, that are maturated in vitro, using coherent anti-Stokes Raman scattering and two-photon fluorescence microscopy. When oocytes were matured in the presence of PA, there were changes in the aggregation pattern and size of lipid droplets that were mitigated by co-incubation in OA. Maturation in PA alone also caused a distinctive disruption of the ER structure. This effect was prevented by incubation of OA with PA. In contrast, maturation of mouse oocytes in medium containing PA was not associated with any significant change in the redox state of mitochondria or the Ca²⁺ content of intracellular stores. These data suggest that a primary effect of saturated FAs such as PA on oocytes is to disrupt the structure of the ER and this is not due to an effect on the mitochondria or Ca²⁺ stores.

Inappropriate corpus luteum (CL) regression can produce pregnancy loss. An experimental model was utilized to investigate regression of accessory CL during pregnancy in dairy cows. Cows were bred (day 0) and treated with gonadotrophin-releasing hormone 6 days later to form accessory CL. Transrectal ultrasound (every other days) and blood samples for progesterone (P4; daily) were performed until day 56 of pregnancy. On day 28, 13 cows were confirmed pregnant, and accessory CL were found contralateral (n = 9) or ipsilateral (n = 4) to previous ovulation. On day 18, CL biopsy was performed to analyze mRNA expression for interferon-stimulated genes (ISGs). Luteolysis occurred more frequently in cows that had contralateral accessory CL (88.9% (8/9)) than in cows with ipsilateral accessory CL (0% (0/4)). Luteolysis of contralateral accessory CL occurred either earlier (days 19–23; 2/8) or later (days 48–53; 6/8) in pregnancy and occurred rapidly (24 h), based on daily P4. After onset of earlier or later accessory CL regression, circulating P4 decreased by 41.2%. There was no difference in luteal tissue mRNA expression for ISGs on day 18 between accessory and original CL and between CL that subsequently regressed or did not regress. On day 56, an oxytocin challenge dramatically increased prostaglandin F2α metabolite (PGFM) in all cows but produced no pregnancy losses, although cows with previous accessory CL regression had greater PGFM. In summary, ipsilateral accessory CL did not regress during pregnancy, whereas most contralateral CL regressed by 63 days of pregnancy, providing evidence for local mechanisms in regression of accessory CL and protection of CL during pregnancy.

The objective of this study was to evaluate the effect of accessory corpus luteum (CL) induction on fertility in dairy cows. On day 5 after artificial insemination (AI), lactating Holstein cows were assigned unequally to receive gonadotrophin-releasing hormone treatment (GnRH) (n = 641) or no treatment (control; n  = 289). Cows had their blood sampled for progesterone (P4), and ovaries were scanned by ultrasound on days 5, 12, 19, 26, 33, 47, and 61 after AI. Pregnancy diagnosis was performed on days 26, 33, 47, and 61. On day 12, cows treated with GnRH were allocated to ipsilateral (n = 239) or contralateral (n = 241) groups based on the side of accessory CL formation relative to previous ovulation. Accessory CL cows had greater P4 than controls. In total, 52.7% (78/148) of pregnant cows in contralateral group had accessory CL regression earlier (<day 33; 30.8%) or later (days 33–61; 69.2%) in pregnancy with coincident decrease in P4. No cows with ipsilateral accessory CL underwent regression. There was no difference in pregnancy/AI among groups. Cows with contralateral accessory CL that underwent early regression had greater pregnancy loss (30%) than controls (10%), or cows with ipsilateral CL (3%) or contralateral CL with either later or no regression (12%). Cows with ipsilateral accessory CL had lower pregnancy loss than controls. In conclusion, elevating circulating P4 by the induction of accessory CL, particularly ipsilateral CL, increases P4 and reduces pregnancy loss. However, contralateral accessory CL that undergoes regression before day 33 of pregnancy has increased pregnancy loss, possibly due to an abrupt decrease in P4 at a pivotal period of pregnancy (days 26–33).

The number of children born after assisted reproductive technology (ART) is accumulating rapidly, and the health problems of the children are extensively concerned. This study aims to evaluate whether ART procedures alter behaviours in male offspring. Mouse models were utilized to establish three groups of offspring conceived by natural conception (NC), in vitro fertilization and embryo transfer (IVF-ET), and frozen-thawed embryo transfer (IVF-FET), respectively. A battery of behaviour experiments for evaluating anxiety and depression levels, including the open field test (OFT), elevated plus maze (EPM) test, light/dark transition test (L/DTT), tail suspension test (TST), forced swimming test (FST), and sucrose preference test (SPT) was carried out. Aged (18 months old), but not young (3 months old), male offspring in the IVF-ET and IVF-FET groups, compared with those in the NC group, exhibited increased anxiety and depression-like behaviours. The protein expression levels of three neurotrophins in PFC or hippocampus in aged male offspring from the IVF-ET and IVF-FET groups reduced at different extent, in comparison to NC group. RNA sequencing (RNA-Seq) was performed in the hippocampus of 18 months old offspring to further explore the gene expression profile changes in the three groups. KEGG analyses revealed the coexisted pathways, such as PI3K-Akt signalling pathway, which potentially reflected the similarity and divergence in anxiety and depression between the offspring conceived by IVF-ET and IVF-FET. Our research suggested the adverse effects of advanced age on the psychological health of children born after ART should be highlighted in the future.

The incidence of polycystic ovary syndrome (PCOS) due to high-fat diet (HFD) consumption has been increasing significantly. However, the mechanism by which a HFD contributes to the pathogenesis of PCOS has not been elucidated. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a key protein that regulates cholesterol metabolism. Our previous study revealed abnormally high PCSK9 levels in serum from patients with PCOS and in serum and hepatic and ovarian tissues from PCOS model mice, suggesting that PCSK9 is involved in the pathogenesis of PCOS. However, the factor that induces high PCSK9 expression in PCOS remains unclear. In this study, Pcsk9 knockout mice were used to further explore the role of PCSK9 in PCOS. We also studied the effects of a HFD on the expression of PCSK9 and sterol regulatory element-binding protein 2 (SREBP2), a regulator of cholesterol homeostasis and a key transcription factor that regulates the expression of PCSK9, and the roles of these proteins in PCOS pathology. Our results indicated HFD may play an important role by inducing abnormally high PCSK9 expression via SREBP2 upregulation. We further investigated the effects of an effective SREBP inhibitor, fatostain, and found that it could reduce HFD-induced PCSK9 expression, ameliorate hyperlipidemia and improve follicular development in PCOS model mice. Our study thus further elucidates the important role of an HFD in the pathogenesis of PCOS and provides a new clue in the prevention and treatment of this disorder.

Obesity, an established risk factor for male subfertility or infertility, is primarily due to genetic and environmental causes. Our earlier studies have shown differential effects of high-fat diet-induced- (DIO) and genetically inherited- (GIO) obesity on DNA methylation in male germline and its subsequent effect on fertility. Here, we hypothesized that the effects of DIO and GIO on histone modifications in male germline could also contribute to fertility defects. We observed that DIO affected both active (H3K4me3, H3ac, and H4ac) and repressive (H3K9me3 and H3K27me3) histone marks in testis and their cell types, whereas GIO solely altered acetylated histones. This correlated with the deregulation of histone-modifying enzymes in the testis of both obese groups. Further, we also observed a decrease in chromatin remodelers in the testis of the DIO group, which were increased in the GIO group. Besides, there was an increase in core histones and a decrease in histone marks along with protamine deficiency in spermatozoa of the DIO group, whereas only H3K4me3 levels were increased in spermatozoa of the GIO group. Moreover, we observed alterations in the expression and enrichment patterns of a few developmental genes harbored by the active histone mark in resorbed embryos and spermatozoa of DIO rats. Together these epigenetic defects in the male germline could alter sperm quality and cause fertility defects in these obese groups. Differential changes in two obese groups could also be attributed to differences in their pathophysiological variations. Our study highlights epigenetic differences between DIO and GIO in the male germline and their subsequent impact on male fertility.

A growing body of research suggests that alterations to the human microbiome are associated with disease states, including obesity and diabetes. During pregnancy, these disease states are associated with maternal microbial dysbiosis. This review discusses the current literature regarding the typical maternal and offspring microbiome as well as alterations to the microbiome in the context of obesity, type 2 diabetes mellitus, and gestational diabetes mellitus. Furthermore, this review outlines the proposed mechanisms linking associations between the maternal microbiome in the aforementioned disease states and offspring microbiome. Additionally, this review highlights associations between alterations in offspring microbiome and postnatal health outcomes.

Lipid droplets (LDs) consist of a core of neutral lipids such as triacylglycerols and cholesteryl esters covered by a phospholipid monolayer. Recent studies have shown that LDs not only store neutral lipids but are also associated with various physiological functions. LDs are found in most eukaryotic cells and vary in size and quantity. It has long been known that mammalian oocytes contain LDs. Porcine and bovine oocytes contain substantial amounts of LDs, which cause their cytoplasm to darken, whereas mouse and human oocytes are translucent due to their low LD content. A sufficient amount of LDs in mammalian oocytes has been thought to be associated with oocyte maturation and early embryonic development, but the necessity of LDs has been questioned because embryonic development proceeds normally even when LDs are removed. However, recent studies have revealed that LDs play a crucial role during implantation and that maintaining an appropriate amount of LDs is important for early embryonic development, even in mammalian species with low amounts of LDs in their oocytes. This suggests that a fine-tuned balance of LD content is essential for successful mammalian embryonic development. In this review, we discuss the physiological importance of LDs in mammalian oocytes and preimplantation embryos based on recent findings on LD biology.

Polycystic ovarian syndrome (PCOS) is the main cause of infertility in women. It is frequently associated with reduced progesterone production by human luteinised granulosa cells (hlGCs). However, the molecular mechanisms involved in these steroidogenesis alterations in PCOS patients are unclear. In a dihydrotestosterone-induced PCOS mouse model, steroid production is maintained in the setting of chemokine-like receptor 1 (Cmklr1) knockout. Thus, chemerin and chemerin receptors in terms of expression and progesterone regulation could be different in control and PCOS hlGCs. We first confirmed that progesterone levels in both plasma (P  < 0.0001) and follicular fluid (FF) (P  < 0.0001) were significantly reduced in PCOS normal weight women compared to control women. These data were associated with a lower STAR mRNA expression in both in vivo (P  < 0.0001) and in vitro (P  < 0.0001) hlGCs from PCOS women. Secondly, chemerin FF levels (P  < 0.0001) and RARRES2 (P  < 0.05) and CMKLR1 (P  < 0.0001) mRNA levels in GCs were higher in PCOS normal weight patients. Thirdly, treatment of hlGCs with a specific nanobody (the VHH CA4910) targeting the human receptor for CMKLR1 leading to its inactivation abolished chemerin-induced progesterone inhibition, suggesting the involvement of CMKLR1 in this process. Furthermore, the inhibition of progesterone secretion induced by chemerin was two-fold higher in PCOS hlGCs (P  < 0.05). Moreover, the VHH CA4910 reinstated a normal progesterone secretion with lower concentrations in PCOS hlGCs, suggesting a different chemerin sensitivity between PCOS and control hlGCs. Thus, chemerin, through CMKLR1, could be involved in the steroidogenesis alterations in PCOS hlGCs.

The nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome plays a critical role in various inflammatory diseases. We sought to investigate the role of NLRP3 inflammasome in uterine activation for labor at term and preterm. We found that NLRP3 inflammasome was activated in the myometrium tissues obtained from the pregnant women undergoing labor at term (TL) compared with those not undergoing labor (TNL) at term. NLRP3 inflammasome was also activated in amnion and chorion-deciduas in TL and preterm labor (PTL) groups. In the mouse model, uterine NLRP3 inflammasome and nuclear factor kappaB (NF-κB) were activated toward term and during labor. Treatment of pregnant mice with lipopolysaccharide (LPS) and RU38486 induced preterm birth (PTB) and also promoted uterine NLRP3 inflammasome and NF-κB activation. Treatment of pregnant mice with NLRP3 inflammasome inhibitor BAY11-7082 and MCC950 delayed the onset of labor and suppressed NLRP3 inflammasome and NF-κB activation in uterus. MCC950 postponed labor onset of the mice with LPS and RU38486 treatment and inhibited NLRP3 inflammasome activation in uterus. Our data provide the evidence that NLRP3 inflammasome is involved in uterine activation for labor onset in term and PTB in humans and mouse model.