Maternal hypertensive condition alters adipose tissue function and blood pressure sensitivity in offspring

Preeclampsia (PE) is characterized by hypertension, proteinuria, and fetal growth restriction during pregnancy, suggesting that the preeclamptic intrauterine environment may affect the growth and health of the offspring. This study aimed to how maternal hypertension affects male offspring growth, focusing on lipid metabolism and blood pressure in mice. Female mice were infused with angiotensin II (Ang II) on gestational day 12. Dysregulation and accumulation of lipid were observed in the placenta of Ang II-induced maternal hypertensive dams, associating with fetal growth restriction. Ang II-offspring showed lower birth weight than in the control-offspring. Isolated and differentiated adipocyte from neonatal mice of Ang II-dams showed higher Pparγ mRNA expression compared with the control group. Lower body weight tendency had continued in Ang II-offspring during long period, body weight of Ang II-offspring caught up the control-offspring at 16 weeks of age. The adipose tissue of Ang II-offspring in adult also showed higher Pparγ mRNA expression with the accumulation of neutrophils and inflammatory monocytes than in those control. In addition, Ang II-offspring had higher basal blood pressure and higher sensitivity to hypertensive stimuli than in the control-offspring. Taken together, maternal hypertension induced by Ang II changes placental function, causing a lower birth weight. These changes in the intrauterine environment may affect adipocyte function and blood pressure of offspring after growth.

Effect of paternal aging and vitrification on mitochondrial DNA copy number and telomere length of mouse blastocysts

In this study, we examined the effects of paternal aging on the mitochondrial DNA copy number (mt-cn), telomere length (TL), and gene expression in mouse embryos. The effects of vitrification on the mt-cn and TL of the embryos derived from young and aged male parents (YF and AF, respectively) were examined. C57BL/6N male mice were used for embryo production at 13-23 and 50-55 weeks of age. Two-cell stage embryos were collected from the oviducts of superovulated female mice (8-15 weeks old) and cultured for 24 h until the 8-cell stage, followed by embryo vitrification. Fresh and vitrified-warmed embryos were incubated for 2 days until the blastocyst stage, and mt-cn and TL were investigated. The cell-free mitochondrial DNA copy number (cf-mt-cn) in the spent culture medium (SCM) of the embryos was then investigated. RNA sequencing of blastocysts revealed that metabolic pathways, including oxidative phosphorylation and mTOR pathways, were enriched in differentially expressed genes. The mt-cn and TL of AF-derived blastocysts were lower and shorter, respectively, than those of YF-derived blastocysts. Paternal aging did not affect the blastocyst rate after vitrification. Vitrification of the 8-cell stage embryos did not affect the mt-cn of the blastocysts. However, it increased the cf-mt-cn (cell-free mt-cn) in the SCM of both YF- and AF-derived embryos. Vitrification did not affect the TL of either YF- or AF-derived embryos. Thus, paternal aging affected the mt-cn and TL of the embryos, but vitrification did not affect these parameters in either age groups.

Gasdermin D regulates soluble fms-like tyrosine kinase 1 release in macrophages

Preeclampsia (PE) is a serious complication, and soluble fms-like tyrosine kinase (sFLT1) released from the placenta is one of the causes of PE pathology. Trophoblasts are the primary source of sFLT1; however, monocytes/macrophages exist enough in the placenta can also secrete sFLT1. Sterile inflammatory responses, especially NLRP3 inflammasome and its downstream gasdermin D (GSDMD)-regulated pyroptosis, may be involved in the development of PE pathology. In this study, we investigated whether human monocyte/macrophage cell line THP-1 cells secrete sFLT1 depending on the NLRP3 inflammasome and GSDMD. To differentiate THP-1 monocytes into macrophages, treatment with phorbol 12-myristate 13-acetate (PMA) induced sFLT1 with interleukin (IL)- 1β, but did not induce cell lytic death. IL-1β secretion induced by PMA inhibited by deletion of NLRP3 and inhibitors of NLRP3 and caspase-1, but deletion of NLRP3 and these inhibitors did not affect sFLT1 secretion in THP-1 cells. Both gene deletion and inhibition of GSDMD dramatically decreased IL-1β and sFLT1 secretion from THP-1 cells. Treatment with CA074-ME (a cathepsin B inhibitor) also reduced the secretion of both sFLT1 and IL-1β in THP-1 cells. In conclusion, THP-1 macrophages release sFLT1 in a GSDMD-dependent manner, but not in the NLRP3 inflammasome-dependent manner, and this sFLT1 release may be associated with the non-lytic role of GSDMD. In addition, sFLT1 levels induced by PMA are associated with lysosomal cathepsin B in THP-1 macrophages. We suggest that sFLT1 synthesis regulated by GSDMD are involved in the pathology of PE.

microRNAs associated with the quality of follicular fluids affect oocyte and early embryonic development

Purpose

Oocyte and embryo quality differs significantly among individuals. Follicular fluid (FF) is a solo environment of oocyte maturation and may flux into the oviduct. Supplementation of in vitro maturation (IVM) and culture (IVC) medium with extracellular vesicles of FFs supports oocyte maturation and embryonic development. We addressed a hypothesis that miRNA profiles in FFs are crucial background of oocyte maturation and embryonic development.

Methods

FFs were collected from the ovaries of individual cows, and the FFs were classified into Good or Poor FF based on the developmental rate to the blastocyst stage of enclosed oocytes. miRNAs associated with the Good FFs were explored using small RNA sequencing. In addition, FFs were classified using the concentration of Good-FF-associated miRNAs. These classified FFs or miRNA were added to the IVM or IVC mediums.

Results

Supplementation of IVM and IVC medium with Good FF improved embryonic development. Good FFs contained miR-151-3p and miR-425-5p at a high concentration compared with those in Poor FFs. FFs selected by the concentration of miR-151-3p and miR-425-5p improved oocyte maturation and embryonic development. Supplementation of IVM or IVC medium with either miR-151-3p or miR-425-5p improved embryonic development to the blastocyst stage.

Conclusion

miRNAs were associated with the Good FFs determined oocyte maturation and embryonic development.

Effect of a low ethanol concentration during in vitro maturation of bovine oocytes and subsequent embryo development

The present study investigated the effects of low ethanol exposure on bovine oocytes. Cumulus-oocyte complexes (COCs) were aspirated for the antral follicles of slaughterhouse-derived ovaries. These COCs were incubated in maturation medium containing 0, 0.1, and 0.2% ethanol for 21 h and subjected to fertilization and in vitro development, and then the rates of nuclear maturation, mitochondrial DNA copy number (Mt-cn) and protein (TOMM40), ATP content and lipid content in oocyte, fertilization, and blastulation were examined. Furthermore, COCs were incubated with 0 or 0.1% ethanol and then mitochondrial membrane potential (MMP) and the glucose consumption of COCs was determined. In addition, gene expression in oocytes was examined by RNA sequencing. Ethanol (0.1 and 0.2%) increased Mt-cn and Mt-protein levels whereas 0.2% ethanol increased the blastulation rate and ATP content in oocytes and decreased lipid content in oocytes. Ethanol (0.1%) increased MMP in oocytes and decreased glucose consumption of COCs. Eight stage embryos derived from 0.1% ethanol treated oocytes had higher levels of trimethyl-H3K9 compared with that of nontreated counterpart. RNA sequencing revealed that differentially expressed genes were associated with glycolysis/gluconeogenesis, carbon metabolism, sphingolipid metabolism, amino acid metabolism, and fatty acid degradation pathways. In conclusion, even 0.1% concentrations of ethanol during in vitro maturation considerably affects oocyte metabolism and histone configuration of embryos.

Beneficial Effect of Polysaccharide Gel Made of Xanthan Gum and Locust Bean Gum on Bovine Oocytes

The present study examined the effect of polysaccharides gels made of xanthan gum and locust bean gum (gel culture system) on oocyte maturation and explored the molecules causing the beneficial effect of the gel culture system. Oocytes and cumulus cells complexes were collected from slaughterhouse-derived ovaries and cultured on a plastic plate or gel. The gel culture system improved the rate of development to the blastocyst stage. The oocytes that matured on the gel contained high lipid contents and F-actin formation, and the resultant 8-cell stage embryos had low DNA methylation levels compared to their plate counterparts. RNA sequencing of the oocytes and embryos revealed the differentially expressed genes between the gel and plate culture systems, and upstream regulator analysis revealed estradiol and TGFB1 as top activated upstream molecules. The medium of the gel culture system contained higher concentrations of estradiol and TGFB1 than that of the plate cultures system. Supplementation of the maturation medium with either estradiol or TGFB1 resulted in high lipid content in oocytes. In addition, TGFB1 improved the developmental ability of the oocytes and increased F-actin content while reducing DNA methylation levels in the 8-cell stage embryos. In conclusion, the gel culture system is useful for embryo production, potentially through the upregulation of TGFB1.

Severe maternal stress alters placental function, resulting in adipose tissue and liver dysfunction in offspring of mice

The developmental origins of health and disease (DOHaD) hypothesis is that future lifestyle diseases in offspring are associated with intrauterine origins in the mother; stress during pregnancy is a risk factor for these diseases in offspring. This study aimed to clarify association of maternal stress with placental dysfunction and offspring development in mice. We applied water stress for 24 h during late pregnancy to explore the metabolic response of offspring to a normal diet (ND) and high-fat diet (HFD). Placental functions were altered by maternal stress, reducing the birth weight of the offspring. In the later life of offspring fed with ND, maternal stress impaired systemic glucose tolerance and altered adipokine secretion in adipose tissue and/or liver. The female offspring of stress-induced dams were light in body weight with lower adipose tissue and smaller adipocytes in both the ND and HFD groups. Abnormal situations, such as dysregulation of plasma glucose levels and fatty liver despite and lower increases in body weight, were observed in the female offspring of stress-induced dams, especially in the HFD-treated group. These findings suggest that long-lasting abnormal conditions and responses to metabolic challenges in maternal stress-induced offspring are linked to placental dysregulation and fetal programming.

Paternal aging impacts mitochondrial DNA content and telomere length in mouse embryos

Mitochondrial DNA (mtDNA) copy number and telomere length (TL) in blastocysts derived from the same male mice at young (10-19-week-old) and aged (40-49-week-old) time points and mtDNA and TL in the hearts of offspring derived from young and aged male mice were examined. Paternal aging correlated with reduced mtDNA and TL in blastocysts. mtDNA and TL were significantly correlated, which was also observed in bovine blastocysts. Moreover, mtDNA in the heart of offspring was reduced in male mice with paternal aging. In conclusion, paternal aging affects embryonic mtDNA and TL, potentially impacting their offspring.

Predicting of molecules mediating an interaction between bovine embryos and uterine epithelial cells

Embryo-maternal reproductive tract interactions are pivotal for successful pregnancy. The present study predicted the molecules modulating embryo-uterine communication by comparing two sets of differentially expressed genes (DEGs): DEGs in uterine epithelial cells (UECs) collected from the uterus with and without blastocysts and DEGs between blastocysts developed in vivo and in vitro. Cows were subjected to super ovulation (SOV), followed by insemination or non-insemination at estrus (SOV + AI and SOV cows). Seven days after estrus, the uterus was flushed to collect UECs, and the presence of blastocysts in the uterus was confirmed. UECs were subjected to RNA-Sequencing (RNA-Seq) to identify DEGs. Publicly available RNA-Seq data of in vivo and in vitro developed bovine blastocysts were used to determine DEGs. Then, using ingenuity pathway analysis, activated- and inhibited-upstream regulators (USRs) for UECs in blastocysts were compared with those for blastocysts developed in vivo. RNA-Seq of UECs revealed that the DEGs were associated with immune response and cell adhesion pathways. The activated and inhibited USRs of UECs derived from SOV+ AI cows overlapped with the activated and inhibited USRs of blastocysts developed in vivo. Overlapping activated USRs include leukemia inhibitory factor, interleukin 6, fibroblast growth factor-2, transforming growth factor beta-1, and epidermal growth factor. In conclusion, the present study predicted the molecules that potentially mediate communication between the developing embryo and the uterus in vivo and prepare the uterus for pregnancy.

miR-17-5p in bovine oviductal fluid affects embryo development

This study identified microRNAs (miRNAs) in bovine oviductal fluids (OFs) and examined the effect of miR-17-5p in OFs on embryonic development to the blastocyst stage. Small RNA-seq of extracellular vesicles of OFs revealed 242 miRNAs. Additionally, analyzing expressions of randomly selected OF-miRNAs with RT-qPCR in the culture medium of oviductal epithelial cells indicated that the abundance of miRNAs in OFs increased during the luteal phase. miR-17-5p mimic-treated eight-cell-stage zona pellucida-free embryos showed improved embryonic development to the blastocyst stage. The effect of the miR-17-5p mimic was confirmed using a dual-luciferase assay and immunostaining. In addition, RNA-seq of the miR-17-5p mimic- or control-treated embryos revealed differentially expressed genes (DEGs), suggesting possible pathways that overlapped with the in silico-predicted pathways for miR-17-5p targeting genes. Furthermore, ingenuity pathway analysis of DEG predicted miR-17 to be a significant upstream regulator. Our results suggest that miR-17-5p in OFs regulates embryonic development in bovines.

NLRP3 inflammasome is involved in testicular inflammation induced by lipopolysaccharide in mice

PROBLEM

Systemic inflammation induced by infection, which is associated with testicular inflammation, predisposes males to subfertility. Recently, the nucleotide-binding oligomerization domain, leucine-rich repeat-, and pyrin domain-containing 3 (NLRP3) inflammasome was identified as a key mediator of inflammation, and excessive activation of the NLRP3 inflammasome was shown to contribute to the pathogenesis of a wide variety of diseases. However, the mechanisms underlying infectious inflammation in the testis remain unclear. We investigated the effect of lipopolysaccharide (LPS)-induced systemic inflammation on the role of the NLRP3 inflammasome in murine testes.

METHOD OF STUDY

We performed in vivo and in vitro studies using an LPS-induced model of NLRP3 inflammasome activation and testicular inflammation.

RESULTS

Intraperitoneal administration of LPS significantly impaired sperm motility in the epididymis of wild type (WT) and NLRP3-knockout (KO) mice. LPS administration stimulated interleukin (IL)-1β production and secretion in the testes of WT mice, and these adverse effects were improved in the testes of NLRP3-KO mice. LPS administration also stimulated neutrophil infiltration as well as its chemoattractant C-C motif chemokine ligand 2 (CCL2) in WT testes, which were suppressed in NLRP3-KO testes. In in vitro cell culture, treatment with LPS and NLRP3 inflammasome activation significantly induced IL-1β and CCL2 secretion from WT but not NLRP3-KO testicular cells.

CONCLUSIONS

Taken together, our results suggest that testicular cells have the potential to secrete IL-1β and CCL2 in an NLRP3 inflammasome-dependent manner and that these cytokines from the testis may further exacerbate testicular function, resulting in subfertility during infectious diseases.

Elevated S100A9 in preeclampsia induces soluble endoglin and IL-1β secretion and hypertension via the NLRP3 inflammasome

OBJECTIVES

Maternal systemic and placental inflammatory responses participate in the pathogenesis of hypertensive disorders of pregnancy including preeclampsia, a pregnancy-specific syndrome, although the role of inflammation remains unclear. The NLRP3 inflammasome has been implicated in the control of sterile inflammation involved in preeclampsia. In the present study, we hypothesized that S100A9, as major alarmin, are associated with the pathogenesis of preeclampsia and induction of a preeclampsia-like phenotype in pregnant mice.

METHODS

Plasma were taken from normal pregnant women and preeclampsia patients. Human placental tissues, trophoblast cell line Sw.71 cells, and human umbilical vein endothelial cells (HUVEC) were treated with S100A9 with or without inhibitors associated with NLRP3 inflammasome. Pregnant mice were administered S100A9.

RESULTS

S100A9 was elevated in plasma and released from placentas of preeclampsia patients. S100A9 activated the NLRP3 inflammasome, resulting in IL-1β secretion, by human placental tissues and trophoblasts. In addition, secretion of soluble endoglin, a main contributor to the pathogenesis of preeclampsia, is regulated via S100A9-stimulated NLRP3 inflammasome activation in the human placenta and HUVECs. S100A9 administration significantly elevated maternal blood pressure and neutrophil accumulation within the placentas of pregnant mice, and both were significantly decreased in Nlrp3-knock out pregnant mice.

CONCLUSION

The results of this study demonstrated that S100A9 acts as a danger signal to activate the NLRP3 inflammasome in the placenta, associating with hypertension during pregnancy.

β-hydroxybutyrate suppresses NLRP3 inflammasome-mediated placental inflammation and lipopolysaccharide-induced fetal absorption

The immune system contributes to the regulation of pregnancy, and the disruption of well-controlled immune functions leads to pregnancy complications. Recently, the nucleotide-binding oligomerization domain, leucine-rich repeat-, and pyrin domain-containing 3 (NLRP3) inflammasome mechanisms [(a protein complex of NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), and caspase-1)] have been reported to play roles in controlling placental inflammation involved in pregnancy pathologies. The ketone body β-hydroxybutyrate (BHB) can suppress NLRP3 inflammasome activation and improve various inflammatory diseases. Therefore, we hypothesized that BHB could suppress activation of the NLRP3 inflammasome in the placenta, resulting in the improvement of pregnancy complications. In human placental tissue culture, treatment with BHB suppressed the secretion levels of inflammatory cytokines, such as interleukin (IL)-1β, IL-6, and IL-8, but did not affect the mRNA expression levels of NLRP3 inflammasome-associated factors. Treatment with BHB reduced IL-1β secretion and the amount of mature IL-1β protein induced by lipopolysaccharide (LPS) stimulation in the placenta. In human trophoblast cells, BHB reduced ASC and activated-caspase-1 expression, resulting in the inhibition of IL-1β secretion. To investigate the effect of BHB during pregnancy, we used an animal model of LPS (100 μg/kg intraperitoneally [i.p.] on gestational day 14)-induced pregnancy complications. Administration of BHB (100 mg/kg i.p.) clearly suppressed the absorption rate and IL-1β production in the placenta induced by LPS in pregnant mice. Moreover, LPS-induced pregnancy abnormalities were improved in NLRP3-deficient mice. These findings suggest that BHB play a role in reducing placental inflammation and pregnancy complications via inhibition of NLRP3 inflammasome activation.

Effect of docosahexaenoic acid on in vitro growth of bovine oocytes

PURPOSE

The present study investigated the effects of docosahexaenoic acid (DHA) on the growth of bovine oocytes.

METHODS

Oocytes and granulosa cell complexes (OGCs) were collected from early antral follicles (0.4-0.7 mm) on the surface of ovaries harvested from a slaughterhouse. The OGCs were cultured with 0, 1, and 10 μmol/L docosahexanoic acid (DHA) for 16 days.

RESULTS

Antrum formation of the OGCs and the number of granulosa cells (GCs) surrounding the oocytes were comparable among groups, whereas supplementation of 0.1 μmol/L of DHA significantly improved oocyte growth. Oocytes grown with DHA had a higher fertilization rate, acetylation levels of H4K12, and ATP contents, as well as a lower lipid content compared with those grown without DHA. In addition, GCs surrounding OGCs grown with DHA had low lipid content compared with vehicle counterparts. Furthermore, when GCs were cultured in vitro, DHA increased ATP production, mitochondrial membrane potential, and reduced lipid content and levels of reactive oxygen species. RNA-seq of GCs revealed that DHA increased CPT1A expression levels and affect genes associated with focal adhesion, oxidative phosphorylation, and PI3K-AKT etc.

CONCLUSION

The results suggest that DHA supplementation affects granulosa cell characteristics and supports oocyte growth in vitro.

Advanced maternal age induces fetal growth restriction through decreased placental inflammatory cytokine expression and immune cell accumulation in mice

Advanced maternal age is a risk factor for female infertility, and placental dysfunction is considered one of the causes of pregnancy complications. We investigated the effects of advanced maternal aging on pregnancy outcomes and placental senescence. Female pregnant mice were separated into three groups: young (3 months old), middle (8–9 months old), and aged (11–13 months old). Although the body weights of young and middle dams gradually increased during pregnancy, the body weight of aged dams only increased slightly. The placental weight and resorption rate were significantly higher, and live fetal weights were reduced in a maternal age-dependent manner. Although mRNA expression of senescence regulatory factors (p16 and p21) increased in the spleen of aged dams, mRNA expression of p16 did not change and that of p21 was reduced in the placenta of aged dams. Using a cytokine array of proteins extracted from placental tissues, the expression of various types of senescence-associated secretory phenotype (SASP) factors was decreased in aged dams compared with young and middle dams. The aged maternal placenta showed reduced immune cell accumulation compared with the young placenta. Our present results suggest that models using pregnant mice older than 8 months are more suitable for verifying older human pregnancies. These findings suggest that general cellular senescence programs may not be included in the placenta and that placental functions, including SASP production and immune cell accumulation, gradually decrease in a maternal age-dependent manner, resulting in a higher rate of pregnancy complications.

Effects of a gel culture system made of polysaccharides (xanthan gum and locust bean gum) on in vitro bovine oocyte development and gene expression of the granulosa cells

Xanthan gum (XG) and locust bean gum (LBG) are nontoxic polysaccharides that produce culture substrates. The present study examined the effect of XG-LBG gel on in vitro bovine oocyte growth and gene expression in granulosa cells. Oocytes and granulosa cell complexes (OGCs) were cultured in vitro on plastic culture plate (Plate) or XG-LBG gel for 16 days. OGCs formed a dome-like cavity surrounding the oocytes on plate but formed a spherical follicle structure on XG-LBG gel. The total granulosa cell numbers of the OGCs and their survival rate was greater for OGCs cultured on XG-LBG gel than for those cultured on plate. Oocytes grown on XG-LBG gels had higher lipid and mitochondrial content, as well as a larger diameter, than their plate counterparts. When oocytes grown in vitro were subjected to in vitro maturation and fertilization, the normal fertilization rate was significantly higher for oocytes developed on XG-LBG gel than that of oocytes cultured on the plate counterpart. RNAseq of the granulosa cells revealed that genes associated with focal adhesion, phosphatidylinositol 3'-kinase-Akt and Hippo signaling, and regulation of actin cytoskeleton were upregulated in granulosa cells of OGCs cultured on XG-LBG gel compared with those cultured on plate.

Effect of maternal aging and vitrification on mitochondrial DNA copy number in embryos and spent culture medium

Maternal aging and vitrification affect mitochondrial quality and quantity in embryos. The present study investigated the effects of maternal aging on mitochondrial DNA (mtDNA) copy number in embryos, and the amount of cell-free mtDNA (cf-mtDNA) in spent culture medium (SCM) of embryos. Moreover, we examined the effects of vitrification on mtDNA copy number in embryos of young and aged cows, and on cf-mtDNA abundance in SCM. Oocytes collected from ovaries of young (20-40 months old) and aged cows (> 140 months old) were used to produce early stage embryos (8-12 cell-stage, 48 h after insemination). These embryos were individually cultured for 5 days, and mtDNA copy number in blastocysts and cf-mtDNA content in SCM, were evaluated by real-time PCR. At 48 h post-insemination, mtDNA copy number in embryos was greater for young cows compared with that of aged cows, whereas no significant difference was observed in cf-mtDNA in the SCM. Next, we addressed whether zona pellucida (ZP) may mask the difference in cf-mtDNA content in SCM. Using ZP-free embryos, we found significantly greater cf-mtDNA content in the SCM of blastocysts derived from aged cows. Furthermore, when embryos were vitrified and warmed, mtDNA copy number in blastocysts derived from young cows was lower, whereas cf-mtDNA content in SCM was greater than in those derived from aged cows. In conclusion, maternal aging affects mitochondrial kinetics and copy number in embryos following vitrification.

Mitochondrial reactive oxygen species regulate mitochondrial biogenesis in porcine embryos

The number of mitochondria in blastocysts is a potential marker of embryo quality. However, the molecular mechanisms governing the mitochondrial number in embryos are unclear. This study was conducted to investigate the effect of reduced mitochondrial reactive oxygen species (ROS) levels on mitochondrial biogenesis in porcine embryos. Oocytes were collected from gilt ovaries and activated to generate over 4 cell-stage embryos at day 2 after activation. These embryos were cultured in media containing either 0.1 μM MitoTEMPOL (MitoT), 0.5 μM Mitoquinol (MitoQ), or vehicle (ethanol) for 5 days to determine the rate of development to the blastocyst stage. The mitochondrial number in blastocysts was evaluated by real-time polymerase chain reaction (PCR). Five days after activation, the embryos (early morula stage) were subjected to immunostaining to determine the expression levels of NRF2 in the nucleus. In addition, the expression levels of PGC1α and TFAM in the embryos were examined by reverse transcription PCR. One day of incubation with the antioxidants reduced the ROS content in the embryos but did not affect the rate of development to the blastocyst stage. Blastocysts developed in medium containing MitoT had lower mitochondrial DNA copy numbers and ATP content, whereas MitoQ showed similar but insignificantly trends. Treatment of embryos with either MitoT or MitoQ decreased the expression levels of NRF2 in the nucleus and levels of PGC1α and TFAM. These findings indicate that reductions in mitochondrial ROS levels are associated with low mitochondrial biogenesis in embryos.

Metabolomic profiles of plasma and uterine luminal fluids from healthy and repeat breeder Holstein cows

Background

Repeat breeding is a critical reproductive disorder in cattle. The problem of repeat breeder cattle remains largely unmanageable due to a lack of informative biomarkers. Here, we utilized metabolomic profiling in an attempt to identify metabolites in the blood plasma and uterine luminal fluids. We collected blood and uterine fluid from repeat breeder and healthy cows on day 7 of the estrous cycle.

Results

Metabolomic analysis identified 17 plasma metabolites detected at concentrations that distinguished between the two groups, including decreased various bile acids among the repeat breeders. However, no metabolites that varied significantly were detected in the uterine luminal fluids between two groups. Among the plasma samples, kynurenine was identified as undergoing the most significant variation. Kynurenine is a metabolite produced from tryptophan via the actions of indoleamine 2,3-dioxygenase (IDO). As IDO is key for maternal immune tolerance and induced in response to interferon tau (IFNT, ruminant maternal recognition of pregnancy factor), we examined the responsiveness to IFNT on peripheral blood mononuclear cells (PBMC) isolated from healthy and repeat breeder cows. The mRNA expression of IFNT-response makers (ISG15 and MX2) were significantly increased by IFNT treatment in a dose-dependent manner in both groups. Although treatment with IFNT promoted the expression of IDO in PBMCs from both groups, it did so at a substantially reduced rate among the repeat breeder cows, suggesting that decreased levels of kynurenine may relate to the reduced IDO expression in repeat breeder cows.

Conclusions

These findings provide valuable information towards the identification of critical biomarkers for repeat breeding syndrome in cattle.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-02755-7.

Deficiency of the RIβ subunit of protein kinase A causes body tremor and impaired fear conditioning memory in rats

The RIβ subunit of cAMP-dependent protein kinase (PKA), encoded by Prkar1b, is a neuronal isoform of the type I regulatory subunit of PKA. Mice lacking the RIβ subunit exhibit normal long-term potentiation (LTP) in the Schaffer collateral pathway of the hippocampus and normal behavior in the open-field and fear conditioning tests. Here, we combined genetic, electrophysiological, and behavioral approaches to demonstrate that the RIβ subunit was involved in body tremor, LTP in the Schaffer collateral pathway, and fear conditioning memory in rats. Genetic analysis of WTC-furue, a mutant strain with spontaneous tremors, revealed a deletion in the Prkar1b gene of the WTC-furue genome. Prkar1b-deficient rats created by the CRISPR/Cas9 system exhibited body tremor. Hippocampal slices from mutant rats showed deficient LTP in the Schaffer collateral-CA1 synapse. Mutant rats also exhibited decreased freezing time following contextual and cued fear conditioning, as well as increased exploratory behavior in the open field. These findings indicate the roles of the RIβ subunit in tremor pathogenesis and contextual and cued fear memory, and suggest that the hippocampal and amygdala roles of this subunit differ between mice and rats and that rats are therefore beneficial for exploring RIβ function.

Comparative analysis of cell-free DNA content in culture medium and mitochondrial DNA copy number in porcine parthenogenetically activated embryos

We examined the effect of ploidy on mitochondrial DNA (mtDNA) copy number in embryos and the amount of cell-free mitochondrial and nucleic DNA content (cf-mtDNA and cf-nDNA) in spent culture medium (SCM). Oocytes collected from the ovaries were matured, activated, incubated in medium containing cycloheximide (CHX) or CHX and cytochalasin B (CB) for 4.5 h to produce haploid or diploid embryos (H-group and D-group embryos). These embryos were cultured for 7 days, and the blastocysts and SCM were examined. The amount of mtDNA and nDNA was determined by real-time PCR. The rate of development to the blastocyst stage was higher for the D-group than for the H-group. Moreover, D-group blastocysts had less mtDNA compared to the H-group blastocysts. After activation, the mitochondrial content was constant before the blastocyst stage in D-group embryos, but increased earlier in H-group embryos. The amount of cf-mtDNA in the SCM of D-group blastocysts was greater than that of H-group blastocysts. However, when the cf-mtDNA in the SCM of 2 cell-stage embryos (day 2 post-activation) was examined, the amount of cf-mtDNA was greater in the H-group than in the D-group embryos. When D-group embryos were cultured for 7 days, a significant correlation was observed between the total cell number of blastocysts and cf-nDNA content in the SCM. Hence, although careful consideration is needed regarding the time point for evaluating mtDNA content in the embryos and SCM, this study demonstrates that mtDNA in the embryos and SCM was affected by the ploidy of the embryos.

IL1B triggers inflammatory cytokine production in bovine oviduct epithelial cells and induces neutrophil accumulation via CCL2

PROBLEM

The oviduct is essential for reproduction. We previously showed that oviduct epithelial cells (OECs) isolated from aged cows expressed higher levels of inflammatory cytokines, including interleukin (IL) 1A and IL1B. In addition, aging is associated with tissue dysfunction and cellular senescence via a senescence-associated secretory phenotype (SASP) and immune cell accumulation. We investigated whether IL1A or IL1B causes SASP production, cellular senescence, and inflammatory responses in bovine OECs.

METHOD OF STUDY

The OECs were isolated from bovine oviducts from young (mean 50.3 months) and aged cows (mean 157.0 months) and cultured.

RESULTS

Treatment with IL1A or IL1B induced SASP production (IL8, IL6, TNFA, and CCL2) and mRNA expression of cell adhesion molecules in bovine OECs, but both IL1s did not induce cellular senescence in OECs and migration of polymorphonuclear neutrophils (PMNs). Cultured medium of OECs treated with IL1s, especially IL1B, dramatically induced PMN migration. Treatment with the CCL2 inhibitor, but not IL8 or its receptor CXCR2 inhibitors, significantly reduced immune cell migration in IL1B-treated OEC-cultured medium. Treatment with IL1B increased PMN adhesion to OECs, resulting in further SASP production in OECs due to a PMN-OEC interaction.

CONCLUSION

We suggest that senescence-associated IL1s cause SASP production in bovine OECs and CCL2 induced by IL1B is essential for the migration of immune cells to OECs. Specifically, IL1B regulates PMN migration and adhesion to bovine OECs, and PMNs accelerate inflammatory cytokine production from bovine OECs via a direct interaction. These phenomena may contribute to chronic oviductal inflammation, resulting in subfertility.

Effect of aging on mitochondria and metabolism of bovine granulosa cells

This study investigated the effect of aging on mitochondria in granulosa cells (GCs) collected from the antral follicles of young and aged cows (25–50 months and over 140 months in age, respectively). When GCs were cultured under 20% O₂ for 4 days, mitochondrial DNA copy number (Mt-number), determined by real-time PCR, increased throughout the culture period, and the extent of increase was greater in the GCs of young cows than in those of old cows. In a second experiment, GCs were cultured under 20% O₂ for 24 h. Protein levels of TOMM20 and TFAM in GCs were lower in aged cows than in young cows, and the amount of reactive oxygen species and the mitochondrial membrane potential were higher, whereas ATP content and proliferation activity were lower, respectively. Glucose consumption and lactate production were higher in the GCs of aged cows than in those of young cows. When GCs were cultured under 5% or 20% O₂ for 24 h, low O₂ decreased ATP content and increased glucose consumption in GCs of both age groups compared with high O₂; however, low O₂ decreased the Mt-number only in the GCs of young cows. In conclusion, we show that aging affects mitochondrial quantity, function, and response to differential O₂ tensions in GCs.

Abundance of cell-free mitochondrial DNA in spent culture medium associated with morphokinetics and blastocyst collapse of expanded blastocysts

Purpose

This retrospective observational study investigated relationships between the abundance of cell‐free mitochondrial DNA (cf‐mtDNA) in spent culture medium (SCM) of human‐expanded blastocysts and their morphokinetics to address the question of whether the abundance of cf‐mtDNA in SCM could predict the quality of blastocysts.

Methods

Embryos (n = 53) were individually cultured in a time‐lapse incubator until they reached the expanded blastocyst stage (5 or 6 days), following which copy numbers of cf‐mtDNA in SCM (20 μL) of expanded blastocysts were determined using real‐time PCR.

Results

The duration between start of blastulation to expanded blastocyst (tEB–tSB) and between that of the blastocyst stage to expanded blastocyst (tEB–tB) significantly and positively correlated with the abundance of cf‐mtDNA in the SCM (tEB–tSB: r = .46; P < .01; tEB–tB: r = .47; P < .01). The abundance of cf‐mtDNA in the SCM was significantly greater in blastocysts with blastocyst collapse (BC), than without BC, and significantly and positively correlated with the number of BC.

Conclusions

The abundance of cf‐mtDNA in the SCM was associated with expansion duration and BC. Thus, cf‐mtDNA abundance in the SCM serves as a marker to predict the quality of expanded blastocysts.

Prediction of major microRNAs in follicular fluid regulating porcine oocyte development

PURPOSE

The aim of the present study was to identify key microRNAs (miRNAs) in porcine follicular fluid (FF) that regulate oocyte growth.

METHODS

miRNAs contained in FF were determined by small RNA-seq of exosome RNA. Upstream regulator miRNA was determined by ingenuity pathway analysis using differentially expressed genes in granulosa cells (GCs) between small follicles (1-2 mm in diameter) and large follicles (3-5 mm), and between follicles containing oocytes of high developmental ability and follicles containing oocytes of low developmental ability. The candidate miRNAs overlapping among the three miRNAs group were determined. Lastly, the effect of supplementation with FF, exosome-depleted FFs, or each miRNA on in vitro oocyte growth was examined.

RESULTS

The miRNAs determined were miR-17, -27, -92a, and -145. These miRNAs were found in the spent culture medium of oocytes and granulosa cells complexes and serum by small RNA sequencing. Culturing of oocytes and granulosa cells complexes collected from porcine early antral follicles (0.5-0.7 mm in diameter) with FF for 14 days improved oocyte growth; depletion of exosomes from the FFs neutralized the beneficial effect observed. miR-92a mimic increased the antrum formation and diameter, together with acetylated levels of H4K12 in oocytes. In addition, supplementation of miRNA mimics miR-17b, -92a, and -145b improved the rate of chromatin configuration, and miR-17b and -92a mimics improved the developmental ability of oocytes to the blastocyst stage.

CONCLUSION

miR-17, -92a, and -145 are major miRNA candidates in follicular fluids regulating oocyte growth.

Xanthan gum and locust bean gum substrate improves bovine embryo development

One of the major difference between the in vivo and in vitro embryonic environments is the stiffness of the culture substrate. Xanthan gum (XG) and locust bean gum (LBG) are natural materials that are safe, inexpensive and easy to handle. In this study, we investigated the effects of using a polysaccharide culture substrate made from 1% XG and 1% LBG (XG-LBG gel) on bovine embryonic development. Oocytes collected from bovine ovaries were subjected to maturation, and fertilization to generate embryos at an early developmental stage (>4 cell stage). Cleaved embryos were further cultured in a well of 96-well cell culture plate coated with or without XG-LBG gel for 5 days. While the developmental rate up to the blastocyst stage did not differ between the two culture systems (control, 38.0 vs. gel, 38.6%), blastocysts developed on the XG-LBG gel produced significantly high cell numbers and ATP content. Embryos cultured on XG-LBG gels for 24 hr had high expression levels of F-actin and a highly even distribution of E-cadherin. In addition, embryos developed on XG-LBG gel demonstrated increased translocation of YAP to the nucleus and increased connective tissue growth factor (CTGF) protein levels (downstream of Hippo signalling). These findings suggest that soft culture substrates improve embryonic development by enhancing mechanotransduction, including YAP-CTGF signalling.

Palmitic acid activates NLRP3 inflammasome and induces placental inflammation during pregnancy in mice

Maternal obesity is one of the major risk factors for pregnancy complications and is associated with low-grade chronic systemic inflammation due to higher levels of pro-inflammatory cytokines such as interleukin (IL)-1β. Pregnant women with obesity have abnormal lipid profiles, characterized by higher levels of free fatty acids, especially palmitic acid (PA). Previously, we reported that PA stimulated IL-1β secretion via activation of NLRP3 inflammasome in human placental cells. These observations led us to hypothesize that higher levels of PA induce NLRP3 inflammasome activation and placental inflammation, resulting in pregnancy complications. However, the effects of PA on NLRP3 inflammasome during pregnancy in vivo remain unclear. Therefore, PA solutions were administered intravenously into pregnant mice on day 12 of gestation. Maternal body weight was significantly decreased and absorption rates were significantly higher in PA-injected mice. The administration of PA significantly increased IL-1β protein and the mRNA expression of NLRP3 inflammasome components (NLRP3, ASC, and caspase-1) within the placenta. In murine placental cell culture, PA significantly stimulated IL-1β secretion, and this secretion was suppressed by a specific NLRP3 inhibitor (MCC950). Simultaneously, the number of macrophages/monocytes and neutrophils, together with the mRNA expression of these chemokines increased significantly in the placentas of PA-treated mice. Treatment with PA induced ASC assembling and IL-1β secretion in macrophages, and this PA-induced IL-1β secretion was significantly suppressed in NLRP3-knockdown macrophages. These results indicate that transient higher levels of PA exposure in pregnant mice activates NLRP3 inflammasome and induces placental inflammation, resulting in the incidence of absorption.

Roadmap to pregnancy in the first 7 days post-insemination in the cow: Immune crosstalk in the corpus luteum, oviduct, and uterus

The first 7 days post-insemination are critical for establishment of pregnancy. The pre-ovulatory luteinizing hormone (LH) surge induces ovulation through disruption of the follicle structure that elucidates pro-inflammatory (Th1) responses. Various types of immune cells are recruited into the corpus luteum (CL) to regulate luteal angiogenesis and progesterone (P4) secretion into the circulation to establish pregnancy. The active sperm-uterine crosstalk also induces Th1 responses, mainly via Toll-like receptor (TLR) 2/4 signaling pathway in vitro. The endometrial glands serve as sensors for sperm signals, which trigger Th1 responses. Conversely, the sperm-oviduct binding generates anti-inflammatory (Th2) responses to support sperm survival until fertilization. It is well-established that embryo-maternal crosstalk starts after the embryo hatches out from the zona pellucida (ZP). However most recently, it was shown that the 16-cell stage bovine embryo starts to secrete interferon-tau (IFNT) that induces Th2 immune responses in the oviduct. Once developing embryos descend into the uterine horn, they induce Th2 responses with interferon-stimulated genes (ISGs) expression in the uterine epithelium and local immune cells mainly via IFNT release. Likewise, multiple embryos in the uterus of superovulated donor cows on D7 post-insemination induce Th2 immune responses with ISGs expressions in circulating immune cells. These findings strongly suggest that the maternal immune system reacts to the embryo during the first 7 days post-insemination to induce fetal tolerance. It became evident that the innate immunity of the developing CL, oviduct, and uterus works together to provide optimal conditions for fertilization and early embryonic development during the first 7 days post-insemination.

Adverse reproductive effects of S100A9 on bovine sperm and early embryonic development in vitro

The phenomenon of aging arises from multiple, complex interactions causing dysfunction in cells and organs. In particular, fertility drastically decreases with age. Previously, we have demonstrated that the functional characteristics of the bovine oviduct and uterus change with the age-dependent upregulation of inflammation and noted that S100A9 triggers inflammatory responses in oviduct epithelial cells. In the present study, we investigated the hypothesis that S100A9 affects reproductive events to aspect such as sperm function, fertilization, and the development of the embryo in cows. To investigate the effect of S100A9 on bovine sperm, we incubated sperms in vitro with S100A9 for 5 h and observed significantly decreased sperm motility and viability. During in vitro fertilization, S100A9 treatment for 5 h did not affect the rate of fertilization, time of first division of embryos, or embryo development to blastocyst stage. Treatment of 2-cell stage embryos with S100A9 for 5 h significantly reduced the proportion of cells undergoing normal division (4-8 cell embryos) and embryo development to the blastocyst stage. In experiment involving 24 h treatment of 2-cell embryos, the development of all embryos stopped at the 2-cell stage in the S100A9-treated group. In blastocyst-stage embryos, S100A9 treatment significantly stimulated the expression of endoplasmic reticulum (ER) and the mRNA expression of ER stress markers, and activated caspase-3 with subsequent nuclear fragmentation. Pre-treatment with an ER stress inhibitor significantly suppressed caspase-3 activation by the S100A9 treatment, suggesting that S100A9 induces blastocyst dysfunction by apoptosis (via caspase-3 activation) depending on ER stress. These results indicate that direct exposure to S100A9 exerted adverse effects on sperm function and embryo development. These findings suggest that excessive dose of S100A9 may have an adverse effect to the reproductive machinery by inducing inflammation and tissue dysfunction.

Role of the NLRP3 Inflammasome in Preeclampsia

Reproduction involves tightly regulated series of events and the immune system is involved in an array of reproductive processes. Disruption of well-controlled immune functions leads to infertility, placental inflammation, and numerous pregnancy complications, including preeclampsia (PE). Inflammasomes are involved in the process of pathogen clearance and sterile inflammation. They are large multi-protein complexes that are located in the cytosol and play key roles in the production of the pivotal inflammatory cytokines, interleukin (IL)-1β and IL-18, and pyroptosis. The nucleotide-binding oligomerization domain, leucine-rich repeat-, and pyrin domain-containing 3 (NLRP3) inflammasome is a key mediator of sterile inflammation induced by various types of damage-associated molecular patterns (DAMPs). Recent evidence indicates that the NLRP3 inflammasome is involved in pregnancy dysfunction, including PE. Many DAMPs (uric acid, palmitic acid, high-mobility group box 1, advanced glycation end products, extracellular vesicles, cell-free DNA, and free fatty acids) are increased and associated with pregnancy complications, especially PE. This review focuses on the role of the NLRP3 inflammasome in the pathophysiology of PE.

Effect of cryopreservation on the ability of granulosa cells to support in vitro development of oocytes derived from porcine early antral follicles

Granulosa cells (GCs) contribute to oocyte development. The present study addressed the effect of cryopreservation on the ability of GCs to support oocyte development. GCs were collected from antral follicles. Oocyte granulosa cell complexes (OGCs) derived from early antral follicles were cultured with additional fresh-GCs or frozen-thawed-GCs for 14 days, and the developmental ability and characteristics of the oocytes grown in vitro were examined. Furthermore, fresh- or frozen-thawed-GCs were cultured for two days, and the effects of cryopreservation on the characteristics of GCs were examined. The developmental ability of blastocysts and the acetylation levels of H4K12 in oocytes grown in vitro did not significantly differ among the three culture conditions: OGCs cultured with additional fresh-GCs, frozen-thawed-GCs, or without additional GCs. Although both fresh- and frozen-thawed-GCs exhibited increased ATP content compared with that in oocytes developed without additional GCs, only fresh-GCs showed significantly increased lipid content in oocytes grown in vitro. ATP content, reactive oxygen content, mitochondrial membrane potential, and mitochondrial DNA copy number were greater in cultured frozen-thawed-GCs compared with fresh-GCs. In contrast, lipid content of cultured frozen-thawed-GCs was lower than that of fresh-GCs. Both fresh- and frozen-GCs support oocyte growth, but cryopreservation changes the properties of GCs in a manner that affects the energy status of oocytes grown in vitro.

Difficulty of predicting early-onset super-imposed preeclampsia in pregnant women with hemodialysis due to diabetic nephropathy by serum levels of sFlt-1, PlGF, and sEng

There are few case reports in which circulating levels of soluble fms-like tyrosine kinase 1 (sFlt-1), placental growth factor (PlGF), and soluble endoglin (sEng) were measured before the onset of super-imposed preeclampsia in women with hemodialysis. A 40-year-old Japanese nulliparous women with hemodialysis due to diabetic nephropathy became pregnant by frozen embryo transfer. Intensive hemodialysis was started at 5 weeks of gestation. Her blood pressure (BP) in the first trimester was around 130/80 mmHg. At 20⁺³ weeks, she was admitted for close monitoring; her BP was 137/75 mmHg. Her BP increased to 157/88 mmHg at 31⁺² weeks, and nifedipine at 20 mg/day was started at 31⁺⁶ weeks. However, the serial longitudinal measurements of sFlt-1, PlGF, and sEng did not predict the onset of super-imposed preeclampsia. Cesarean section was performed at 33⁺⁶ weeks due to uncontrollable hypertension. A healthy female infant weighing 2138 g was delivered. As for the changes of biomarkers between just before and just after hemodialysis, sFlt-1 was significantly higher just after compared with just before hemodialysis (5774 ± 1875 pg/mL vs. 2960 ± 905 pg/mL, respectively, p < 0.001). PlGF was also significantly higher just after compared with just before hemodialysis (2227 ± 1038 pg/mL vs. 1377 ± 614 pg/mL, respectively, p < 0.001). However, the sFlt-1/PlGF ratio and sEng levels were not significantly different between just before and just after hemodialysis (p = 0.115, p = 0.672, respectively). In conclusion, prediction of early-onset super-imposed preeclampsia using angiogenic and anti-angiogenic markers in pregnant women with hemodialysis might be difficult.

Xanthan gum and Locust bean gum gel supports in vitro development of porcine oocytes derived from early antral follicles

Early antral follicle (EAF)-derived porcine oocytes develop more readily on polyacrylamide-gel (PAG) than on plastic plates. Xanthan gum (XG) and locust bean gum (LBG) are edible polysaccharides. We investigated XG-LBG gel supports in the development of EAF-derived porcine oocytes. XG and LBG were mixed in a 1:1 ratio to form a substrate. We cultured oocyte granulosa cell complexes (OGCs) from the EAFs on XG-LBG gels of various concentrations. The oocyte diameters were comparable among the 0.3, 0.5, and 1.0% gels; granulosa cell proliferation was greater on the 1.0% gel. The proliferation and survival rates of the granulosa cells, and the histone H4 at lysine 12 acetylation levels were higher in OGCs cultured on 1.0% XG-LBG than those grown on 0.3% PAG. Development to the blastocyst stage was 13.8% for the XG-LBG gels and 9.4% for PAG. In conclusion, XG-LBG are safe and efficient substrates for in vitro culture of oocytes.

Modification of the medium volume and gel substrate under in vitro culture conditions improves growth of porcine oocytes derived from early antral follicles

This study compared the effects of different volumes of culture medium for the in vitro growth of oocytes derived from porcine early antral follicles (EAFs). Oocyte granulosa cell complexes (OGCs) were collected from EAFs (0.5–0.7 mm in diameter) and individually cultured for 14 days. When OGCs were cultured in 1 ml of medium with or without polyacrylamide gel (PAG), the presence of PAG supported granulosa cell (GC) proliferation and oocyte growth. When OGCs were cultured in 0.2 or 1 ml of medium on PAG, the number of GC in the OGC culture and the developmental ability of the oocytes cultured in vitro were significantly higher for the 1 ml of culture medium group than for the 0.2 ml group. In conclusion, a combination of a large volume of culture medium with PAG improved the growth and developmental ability of the oocytes cultured in vitro, which were comparable to the oocytes collected from large antral follicles.

The transfer of parthenogenetic embryos following artificial insemination in cows can enhance pregnancy recognition via the secretion of interferon tau

Repeat breeding is a reproductive disorder in cattle. Embryo transfer following artificial insemination (AI) improves pregnancy rate by replenishing interferon tau (IFNT), but it results in a notably higher rate of twin occurrence. This study hypothesized that parthenogenetic (PA) embryo transfer following AI (AI + PA) could improve the conception rate because that PA embryo become as a supplemental source of IFNT without twins. PA embryos showed higher IFNT mRNA expression than in vitro fertilization (IVF) embryos. An examination of the effect of the cultured conditioned media (CM) of PA or IVF embryos on Madin-Darby bovine kidney cells with stably introduced promoter-reporter constructs of interferon-stimulated gene 15 (ISG15, marker of IFN response) showed higher stimulation levels of ISG15 promoter activity with PA than with IVF embryo. We investigated in vivo the effect of AI + PA on healthy Japanese Black cattle. Cattle transferred with PA embryo alone were non-fertile, but those that underwent AI + PA showed a pregnancy rate of 53.3%, the similar as that with AI alone (60%). In pregnant cattle in AI + PA group, adding the PA embryo upregulated the expression of ISGs and plasma progesterone concentration. No twin were generated in AI only and AI + PA groups. Using repeat breeding Holstein cows that did not become pregnant with 4-9 times of AI, transfer of PA embryo following AI resulted in a higher pregnancy rate than that of control (AI only). We suggest that AI + PA may be beneficial for improving maternal pregnancy recognition in repeat breeder cattle while avoiding twin generation.

Palmitic acid induces ceramide accumulation, mitochondrial protein hyperacetylation, and mitochondrial dysfunction in porcine oocytes

Low oocyte quality is a possible causal factor of obesity-induced infertility. High palmitic acid (PA) concentration in follicular fluid is a crucial feature noted in obese women. This study examined how high PA concentration reduced mitochondrial quality in oocytes and investigated a possible countermeasure against mitochondrial dysfunction. Cumulus cell-oocyte complexes were obtained from the ovaries of gilts, and incubated in medium containing PA (0.5 mM) or vehicle (BSA) for 44 h. Culturing oocytes at high PA concentration induced mitochondrial dysfunction determined by high reactive oxygen species and low ATP content in oocytes. Furthermore, high PA levels increased mitochondrial acetylation levels determined by a high degree of co-localization of TOMM20 and acetylated-lysine. In addition, high PA levels reduced the expression of Sirtuin 3 (SIRT3) and phosphorylated AMP-activated protein kinase (AMPK), while the AMPK activator, AICAR, restored mitochondrial function as well as oocyte ability and reduced the acetylation of mitochondrial protein. Supplementation of culture medium with dorsomorphin dihydrochloride (an AMPK inhibitor) reduced mitochondrial function and increased mitochondrial protein acetylation. Treatment of oocytes with LB100 (an inhibitor of AMPK dephosphorylation) reduced mitochondrial acetylation levels and restored mitochondrial function. Furthermore, high PA levels increased ceramide accumulation in oocytes, and addition of ceramide to the culture medium also induced mitochondrial dysfunction and increased mitochondrial acetylation. This detrimental effect of ceramide was diminished by AICAR treatment of oocytes. Our results indicated that PA induces ceramide accumulation and downregulates the AMPK/SIRT3 pathway causing mitochondrial protein hyperacetylation and dysfunction in oocytes.

S100A8, which increases with age, induces cellular senescence-like changes in bovine oviduct epithelial cells

PROBLEM

The oviduct is an essential component in reproduction and oviduct epithelial cells (OECs) secrete various types of cytokine. However, mechanisms of aging and inflammation of OECs are unknown. We previously reported the age-dependent functional changes of bovine OECs such that aged OECs expressed higher levels of inflammatory cytokines. We selected S100A8 and S100A9 as molecules expressed more highly in aged OECs, as candidates to induce age-related changes, and investigated using bovine OECs.

METHOD OF STUDY

The OECs were isolated from bovine oviductal tissues (Aged, more than 120 months; Young, between 30 and 50 months) and cultured.

RESULTS

Aged OECs exhibited higher senescence-associated (SA)-β-gal staining (a biomarker of cellular senescence) and mRNA expression of SA-inflammatory cytokines than young OECs. Cellular senescence occurred in both young and aged OECs upon passaging the cells. Treatment with S100A8, but not S100A9, resulted in the induction of cellular senescence in bovine OECs. Both S100A8 and S100A9 stimulated the secretion of the inflammatory cytokine IL-8 from bovine OECs. S100A8-induced IL-8 secretion was dependent on receptor RAGE, AP-1 activation, and reactive oxygen species production. In addition, S100A8 reduced the content of collagen while inducing the expression of matrix metalloproteinases, suggesting the induction of dysregulation of the extracellular matrix in OECs.

CONCLUSION

We suggest that bovine OECs recognize an excessive increase in age-associated DAMPs, such as S100A8 and S100A9, and that these signals may contribute to chronic oviductal inflammation, resulting in infertility associated with oviductal dysfunction.

Follicular factors determining the developmental competence of porcine oocyte

PURPOSE

This study aimed to examine the relationship between granulosa cells (GCs), number of follicles, and the ability of follicular fluid to support in vitro growth of oocytes.

METHODS

The culture medium was supplemented with follicular fluid (FF) collected from GC-rich ovaries and GC-poor ovaries, and its effect on in vitro growth and quality of oocytes derived from early antral follicles (EAFs) was assessed.

RESULTS

GC-rich FF treatment enhanced oocyte growth and augmented changes in the chromatin configuration and lipid content of oocytes when compared to oocytes treated with GC-poor FF. Moreover, oocytes treated with GC-rich FF had a higher ability to progress to the blastocyst stage, than oocytes derived from large antral follicles (3-5 mm in diameter). In addition, supplementation of the culture medium with either GC-rich or GC-poor FF enhanced histone acetylation in oocytes grown in vitro.

CONCLUSION

GC-rich FF contains key factors that support in vitro oocyte growth; hence, oocytes grown in GC-rich FF medium had high developmental competence, which was comparative to the oocytes grown in vivo.

Cell-free DNA in medium is associated with the maturation ability of in vitro cultured oocytes

Follicular fluid contains cell-free DNA (cfDNA), which may serve as a useful biomarker of oocyte ability. The present study evaluates whether nuclear and mitochondrial cfDNAs in conditioned oocyte growth medium determine the quality of oocytes cultured in vitro. Oocyte and granulosa cell complexes (OGCs) derived from early antral follicles of gilt ovaries were cultured for 14 days and the amount of cfDNA and lactate concentration in the conditioned culture medium were measured and compared to evaluate oocyte maturation ability. The amount of nuclear cfDNA, but not mitochondrial cfDNA, strongly correlated with the number of dead cells in OGCs. Furthermore, low mitochondrial cfDNA content and high lactate concentration in the medium was associated with high maturation ability of oocytes cultured in vitro. In conclusion, the amounts of nuclear and mitochondrial cfDNAs differentially reflect the conditions of OGCs, and low mitochondrial cfDNA, low glucose content, and high lactate concentration in the medium are associated with the proper maturation of oocytes.