Endocrine and paracrine control of follicular development and ovulation rate in farm species

Periovulatory anticoagulant therapy enhances embryo recovery rates in superovulated mares

Although protocols for superovulation have been described in horses, this technique has been discouraged due to the low embryo recovery rates in superovulated mares. The reason for these poor results is poorly understood, but the formation of a blood clot in the ovulation fossa following ovulations has been hypothesized. Therefore, this study aimed to assess the safety and effect of periovulatory anticoagulant therapy on embryo recovery of superovulated mares. In experiment 1, five mares were assigned to receive five anticoagulant treatments in a crossover design: intravenous injections of 150 (H1), 300 (H2), 400 (H3), 450 (H4), 600 (H5) IU/kg of unfractionated heparin (UFH, heparin sodium); and had blood samples sequentially collected for up to 48 h post-treatment to test Prothrombin (PT) and activated partial thromboplastin time (aPTT). In experiment 2, four mares were treated in a crossover design with intravenous injection of 450 IU/kg of UFH and 1 mg/kg of low molecular weight heparin (LMWH, enoxaparin) and had blood collected as previously for analysis of plasma anti-Xa activity. In experiment 3, eleven mares had four cycles randomly assigned to four groups. In the control group, mares did not receive any treatment. In contrast, in groups G1, G2, and G3, mares were superovulated with equine pituitary extract and treated 34 h after the induction of ovulation with a placebo (NaCl 0.9 %, G1), 450 IU/kg of UFH (G2), or 1 mg/kg of LMWH. Mares in all groups had ovulation induced with hCG plus histrelin acetate and were bred with fresh semen from one stallion. Embryo flushing was performed nine days post-ovulation. In experiment 1, only mares in groups H4 and H5 had increased aPTT and PT for up to 12 h, and in all groups, aPTT and PT values returned to baselines at 24 h post-treatment. In experiment 2, plasma anti-Xa activity was increased by both therapies for up to 12 h after treatment and was at baseline levels 24 h post-treatment. In experiment 3, periovulatory therapy with anticoagulants increased embryo recovery rates per cycle (G2, 250 %; G3, 260 %) compared to control-assigned cycles (60 %; P < 0.05), whereas G1-assigned cycles (160 %) had intermediate embryo recovery. In conclusion, periovulatory anticoagulant therapies may be an alternative to improve embryo recovery in superovulated mares.

Combined analyses of mRNA and miRNA transcriptome reveal the molecular mechanisms of theca cells physiological differences in geese follicular selection stage

In avian, follicular selection is a key molecular event that can determine avian egg production. Theca cells (TC) are the main components of follicles, the molecular mechanisms about TCs physiological differences during follicle selection stage are still unclear. This study revealed significant differences in proliferation, apoptosis, lipid synthesis, and steroid secretion levels between prehierarchical theca cells (phTC) and hierarchical theca cells (hTC) of Tianfu meat-type geese. A total of 1,559 differentially expressed genes (DEG) and 71 differentially expressed miRNAs (DEM) were identified between phTCs and hTCs, respectively. Functional enrichment analysis results showed that 143 DEGs were enriched in the pathways related to cell proliferation/apoptosis and lipid/steroid metabolism. Protein-protein interaction (PPI) network results indicated the 143 DEGs have functional interactions. Additionally, the predicted target genes of 71 DEMs were jointly analyzed with the above 143 DEGs, and the results showed that 15 DEMs and 17 DEGs with targeted relationships were found. Among them, miR-202-5p was significantly down-regulated both in hTCs and hierarchical theca layers, and target prediction results showed that miR-202-5p may affect TCs proliferation/apoptosis by targeting CHPT1 to regulate the expression levels of CCN1/FOXO3; meanwhile, may affect TCs lipid/steroid metabolism and proliferation/apoptosis by targeting CHPT1 to regulate the expression levels of p53/ABCA1/SREBP-2. This study provides new insights into the regulatory mechanisms of TCs physiological differences during goose follicle selection.

Pleomorphic adenoma gene1 in reproduction and implication for embryonic survival in cattle: a review

The pleomorphic adenoma gene1 (PLAG1) encodes a DNA-binding, C2H2 zinc-finger protein which acts as a transcription factor that regulates the expression of diverse genes across different organs and tissues; hence, the name pleomorphic. Rearrangements of the PLAG1 gene, and/or overexpression, are associated with benign tumors and cancers in a variety of tissues. This is best described for pleomorphic adenoma of the salivary glands in humans. The most notable expression of PLAG1 occurs during embryonic and fetal development, with lesser expression after birth. Evidence has accumulated of a role for PLAG1 protein in normal early embryonic development and placentation in mammals. PLAG1 protein influences the expression of the ike growth factor 2 (IGF2) gene and production of IGF2 protein. IGF2 is an important mitogen in ovarian follicles/oocytes, embryos, and fetuses. The PLAG1-IGF2 axis, therefore, provides one pathway whereby PLAG1 protein can influence embryonic survival and pregnancy. PLAG1 also influences over 1,000 other genes in embryos including those associated with ribosomal assembly and proteins. Brahman (Bos indicus) heifers homozygous for the PLAG1 variant, rs109815800 (G > T), show greater fertility than contemporary heifers with either one, or no copy, of the variant. Greater fertility in heifers homozygous for rs109815800 could be the result of early puberty and/or greater embryonic survival. The present review first looks at the broader roles of the PLAG1 gene and PLAG1 protein and then focuses on the emerging role of PLAG1/PLAG1 in embryonic development and pregnancy. A deeper understanding of factors which influence embryonic development is required for the next transformational increase in embryonic survival and successful pregnancy for both in vivo and in vitro derived embryos in cattle.

Prostaglandins as local regulators of ovarian physiology in ruminants

Prostaglandins are synthesized from arachidonic acid through the catalytic activities of cyclooxygenase, while the production of different prostaglandin types, prostaglandin F2 alpha (PGF) and prostaglandin E2 (PGE), are regulated by specific prostaglandin synthases (PGFS and PGES). Prostaglandin ligands (PGF and PGE) bind to specific high-affinity receptors and initiate biologically distinct signalling pathways. In the ovaries, prostaglandins are known to be important endocrine regulators of female reproduction, in addition to maintaining local function through autocrine and/or paracrine effect. Many research groups in different animal species have already identified a variety of factors and molecular mechanisms that are responsible for the regulation of prostaglandin functions. In addition, prostaglandins stimulate their intrafollicular and intraluteal production via the pathway of prostaglandin self-regulation in the ovary. Therefore, the objective of the review article is to discuss recent findings about local regulation patterns of prostaglandin ligands PGF and PGE during different physiological stages of ovarian function in domestic ruminants, especially in bovine. In conclusion, the discussed local regulation mechanisms of prostaglandins in the ovary may stimulate further research activities in different methodological approaches, especially during final follicle maturation and ovulation, as well as corpus luteum formation and function.

Miracle Tree (Moringa oleifera) Attuned GFAP and Synaptophysin Levels, Oxidative Stress and Biomarkers in Cerebellar Fluorosis of Pregnant Rats

<b>Background and Objective:</b> Cerebellar fluorosis is a health issue associated with excessive exposure to fluoride (F) either in direct or indirect ways as pesticides, drinking water and caries preventing prescriptions. It is characterized by elevation in oxidative stress, inflammation, demyelination and Purkinje cell loss. <i>Moringa oleifera</i> (M), is a widely cultivated plant used as a health-booster agent in modulating various disorders because of its high content of vitamins and minerals. The beneficial effect of moringa against fluoride-induced cerebellar toxicity in pregnant rats was investigated in this study. <b>Materials and Methods:</b> Twenty pregnant rats were administered daily 300 mg kg¹ <i>M. oleifera</i> aqueous extract incorporated with 10 mg kg¹ of F intoxication from the 1st day of gestation until the 20th day. Following the termination of the trial, sera were collected and cerebellar tissue was removed for further examinations, along with the assessment of maternity. <b>Results:</b> The <i>M. oleifera</i> significantly normalized serum FSH, LH, progesterone, dopamine and serotonin levels of F-intoxicated mothers. Additionally, <i>M. oleifera</i> markedly prevented the lipid peroxidation and DNA fragmentation indicated by the tail length and moment in comet assay (-34.4 and -75.3%, respectively, when compared to the fluoride intoxicated group), while sustaining the levels of SOD and CAT revealing its antioxidant activity. The <i>M. oleifera</i> regressed the cerebellar α-amylase (-25.4%) and acetylcholinesterase activity (-40.6%), also attenuated GFAP (-73.4%, p<0.0001), synaptophysin level (216.6%, p<0.0001) and IL-6 expression (-91.2%) comparing to fluoride only treated mothers. <b>Conclusion:</b> Histological and ultrastructural examinations confirmed the recuperating effects of <i>M. oleifera</i> on mothers' cerebellar tissue intoxicated with fluoride indicated by intact folia and restored Purkinje cells number and architecture. The maternal study emphasized the anti-abortifacient activity of moringa against fluoride induced-fetotoxicity.

The impact of non-caloric artificial sweetener aspartame on female reproductive system in mice model

BACKGROUND

Artificial sweeteners, used as sugar substitutes have found their ways into almost all the food items due to the notion that they are non-caloric. Aspartame is used in numerous food products throughout the world. The primary users of aspartame include diabetics and calorie conscious people who intend to limit their calorie intake.

METHODS

Female Swiss albino mice were divided into three groups (12 mice each) for the duration of 30 and 60 days consecutively. The treatment groups received 40 mg/kg b. w. aspartame orally. Hormone assays using ELISA and tissue histopathology have been performed along with the fertility assay to access the treatment outcomeon the fertility of treated mice in comparison to controls.

RESULTS

Present study reports that female mice treated with aspartame for 30 and 60 days showed significant reduction in body weight, relative organ weight of (liver and kidney) and gonadosomatic index. These changes were more significantly recorded in 60 days treatment group. Aspartame treated animals for 30 and 60 days showed duration-dependent decrease gonandotropins (follicle stimulating hormone and luteinizing hormone), and steroids (estradiol and progesterone). Moreover, severe histopathological changes, reduction in number of growing follicles, degenerative changes in follicular structure, corona radiata and zonagranulosa were also observed. Besides, histomorphological changes were also observed in the uterine structure including atrophic uterine endometrial glands, contracted endometrial lining, disruption of the endometrial structure and the shapes of blood vessels were also altered.

CONCLUSION

Non-nutritive artificial sweeteners including aspartame negatively impact the function of ovaries and feedback mechanism of reproductive hormones by affecting the hypothalamic-pituitary-gonadal axis. In light of present findings the aspartame negatively impacted the reproductive system of female mice. More studies are required to identify the molecular mechanism and the pathways involved.

Follicle development in pigs: State of the art

Understanding the factors and pathways involved with recruitment, atresia, and selection of follicles in the pig, may provide insight into approaches to limit fertility failures. Antral follicles depend upon FSH to the 2-3 mm stage, become codependent upon LH at 4-5 mm, and rely on LH when >5 mm. Within the follicle, gonadotropin binding, steroids, growth factors, and inhibin interact to determine the fate of the follicle. Continuous recruitment appears likely for follicles, and once >1 mm, they may have a limited period for survival, before selection or atresia. If true, then the number of healthy follicles that can respond to a hormone signal for selection, could vary by size and development stage. Which follicles are selected may depend upon their age, numbers of capillaries, granulosa and thecal cells, and FSH and LH receptors. This might also suggest that factors such as management, nutrition, and stress in prior weeks, could affect different cohorts of follicles to determine which of those from the ovarian population will be selected.

IVM Advances for Early Antral Follicle-Enclosed Oocytes Coupling Reproductive Tissue Engineering to Inductive Influences of Human Chorionic Gonadotropin and Ovarian Surface Epithelium Coculture

In vitro maturation (IVM) is not a routine assisted reproductive technology (ART) for oocytes collected from early antral (EA) follicles, a large source of potentially available gametes. Despite substantial improvements in IVM in the past decade, the outcomes remain low for EA-derived oocytes due to their reduced developmental competences. To optimize IVM for ovine EA-derived oocytes, a three-dimensional (3D) scaffold-mediated follicle-enclosed oocytes (FEO) system was compared with a validated cumulus-oocyte complex (COC) protocol. Gonadotropin stimulation (eCG and/or hCG) and/or somatic cell coculture (ovarian vs. extraovarian-cell source) were supplied to both systems. The maturation rate and parthenogenetic activation were significantly improved by combining hCG stimulation with ovarian surface epithelium (OSE) cells coculture exclusively on the FEO system. Based on the data, the paracrine factors released specifically from OSE enhanced the hCG-triggering of oocyte maturation mechanisms by acting through the mural compartment (positive effect on FEO and not on COC) by stimulating the EGFR signaling. Overall, the FEO system performed on a developed reproductive scaffold proved feasible and reliable in promoting a synergic cytoplasmatic and nuclear maturation, offering a novel cultural strategy to widen the availability of mature gametes for ART.

Effect of Sodium Fluoride on Reproductive Function Through Regulating Reproductive Hormone Level and Circulating SIRT1 in Female Rats

Fluorosis causes female reproductive dysfunction with reduced fertility without established pathogenesis. To clarify the mechanism, Sprague-Dawley female rats were selected with drinking water containing 0, 50 (low), 100 (moderate), and 150 mg/L (high) sodium fluoride (NaF) for a short (2 months), medium (4 months), and long term (6 months). The water consumption and body weight of female rats were recorded daily. The effect of NaF on the estrous cycle was examined by vaginal smears and recorded in different term treatments. Female and male rats were mated in a 2:1 ratio for 1 week at 2-, 4-, and 6-month treatment time for mating performance and fertility rate. Selected female rats were executed for tissue and blood collection at different treatment terms. Twenty-four-hour urine sample from each female rat was collected using the metabolic cage. The levels of steroid hormones and silent information regulator 2 homolog 1 (SIRT1) in serum were measured by appropriate ELISA kits. Body weight of the high NaF group was significantly less during short-term treatment than that of other treatment groups or control group. Urinary fluoride concentration was increased linearly with treatment time. Treatment of NaF significantly decreased steroid hormone level while increased SIRT1 level in the serum. In addition, NaF treatment significantly decreased pregnancy rate. It is concluded that NaF inhibits the secretion of hormone and estradiol (E₂) release from the ovary, thereby reducing the rate of pregnant. SIRT1 may be involved in this NaF-induced reproductive dysfunction in female rats through regulating reproductive hormone, FSH, and LH secretion.

Transcriptome analysis reveals mRNAs and long non-coding RNAs associated with fecundity in the hypothalamus of high-and low-fecundity goat

As an important organ that coordinates the neuroendocrine system, the hypothalamus synthesizes and secretes reproductive hormones that act on the goat organism, thereby precisely regulating follicular development and reproductive processes in goats. However, it is still elusive to explore the mechanism of hypothalamic effects on goat fertility alone. Therefore, RNA-seq was used to analyze the gene expression in hypothalamic tissues of goats in high fertility group (HFG: litter size per litter ≥2) and low fertility group (LFG: litter size per litter = 1), and identified the differential lncRNAs and mRNAs and their associated pathways related to their fertility. The results showed that a total of 23 lncRNAs and 57 mRNAs were differentially expressed in the hypothalamic tissue of high and low fertility goats. GO terms and KEGG functional annotation suggest that DE lncRNAs and DE mRNAs were significantly enriched in hormone-related pathways regulating ovarian development, hormone synthesis and secretion, regulation of reproductive processes, Estrogen signaling pathway, Oxytocin signaling pathway and GnRH signaling pathway. And we constructed a co-expression network of lncRNAs and target genes, and identified reproduction-related genes such as NMUR2, FEZF1, and WT1. The sequencing results of the hypothalamic transcriptome have broadened our understanding of lncRNA and mRNA in goat hypothalamic tissue and provided some new insights into the molecular mechanisms of follicle development and regulation of its fertility in goats.

GnRH agonists: Updating fixed-time artificial insemination protocols in sows

Protocols for fixed-time artificial insemination (FTAI) in swine reproduction can help increase genetic improvement and production efficiency. Different gonadotropin-releasing hormone (GnRH) agonists have been developed to gain better control of follicular development, timing, and ovulation quality; therefore, they have been extensively used in FTAI protocols. This literature review resumes the most important characteristics of the physiology of follicular development and ovulation in sows, followed by a discussion about the hormonal alternatives available to induce ovulation (human chorionic gonadotropin, hCG; porcine luteinizing hormone, LH and GnRH agonists). Also, ovulation induction failures with GnRH agonists are described. Finally, current FTAI protocols with GnRH agonists are resumed and discussed. FTAI with GnRH agonists has proven to be an efficient, successful reproductive protocol that can be implemented in pig farms due to better knowledge of an endocrine system that regulates follicular development and ovulation and increased availability of several GnRH agonists that allow more efficient reproductive swine programs.

The effect of progesterone injection combined with prostaglandineF2α, GnRH and hCG administrations on the pregnancy and lambing rate of lactating and non-lactating fat-tailed ewes during the breeding season

The objective was to compare the effect of human chorionic gonadotropin (hCG) and gonadotropin-releasing hormone (GnRH) on the pregnancy and lambing rate of treated ewes with a short-term progesterone (P4) injection during the breeding season. In Exp 1, non-lactating ewes (n = 158) were used and received P₄ , three times every 48 h and received PGF_2α along with the last dose of P4. Ewe received hCG (n = 79, 3PHCG, IM) or GnRH (n = 79, 3PGnRH, IM) 24 h after the last dose of P4 treatment. In the Exp 2, lactating ewes (n = 62) received P4 and hCG (n = 24, 3PHCG) or GnRH (n = 24, 3PGnRH) similar to Exp 1, or considered as control (n = 14) and received PGF2α 48 h before ram release. Rams were released into the studied ewe's flock 24 h after the hCG or GnRH administration, and pregnancy diagnosis was performed on day 50 after ram release. In Exp 1, all reproductive indices were not significant between groups except twin lambing rate, that was higher in the 3PHCG (11.3%) compared with the 3PGnRH (1.9%) group (p = .05). There were no significant differences in overall pregnancy and lambing rates between 3PHCG (70.9% and 67.1%) and 3PGnRH (69.6% and 68.4%) groups (p > .05). In Exp 2, all reproductive parameters were not significant between 3PHCG and 3PGnRH groups (p > .05). There was significant difference in overall oestrous rate between control (35.7%) and treatment (3PHCG, 70.9% and 3PGnRH, 79.2%) groups. To conclude, administration of GnRH can be a good alternative to hCG injection under field conditions.

Optimization of recovery and maturation methods for cumulus-oocyte complexes in jennies

Embryo production in donkeys is inefficient compared with that in other livestock. Obtaining a sufficient number of MII oocytes is the first step to solving this problem. In this study, the number, morphology and maturation rates of cumulus-oocyte complexes (COCs) obtained from abattoir-derived ovaries or live jennies were compared. The diameter of follicles from abattoir-derived ovaries was measured and divided into group 1 (2-6 mm), group 2 (6-10 mm), group 3 (10-20 mm), group 4 (20-28 mm) and group 5 (>28 mm). The results showed that the number of follicles per ovary in group 2 (3.6 ± 0.28) and 3 (4.2 ± 0.90) was higher than that in the other groups (p < .05). The recovery rate in group 3 was higher than group 1 (48.8% vs. 26.8%, p = .00), but lower than group 5 (48.8% vs. 76.5%, p = .025). The percentage of grade A COCs in group 3 was higher than group 2 (59.3% vs. 39.5%, p = .00) and group 1 (59.3% vs. 26.7%, p = .00). Moreover, the percentage of grade A COCs in group 4 (55.0%, p = .710) and group 5 (46.2%, p = .351) was reduced compared with that in group 3. From the above results, the developing follicles (group ovum pick-up [OPU], 10-20 mm) and preovulation follicles (group OPU-Preov, >35 mm) were aspirated from live jennies using OPU. Although there was no difference in the recovery rates of COCs between group 3 and OPU (48.8% vs. 43.0%, p = .184), the percentage of grades A COCs in group OPU was higher than group 3 (72.5% vs. 59.3%, p = .036). There was no difference in the maturation rate between group 3 and OPU (60.3% vs. 69.3%, p = .171) after the COCs matured in vitro. The rates of recovery (72.2%) and maturation (92.3%) in group OPU-Preov were higher than those in other groups (p < .05). Moreover, the effects of maturation time and serum type on maturation rates were evaluated in groups B44 (44 h, FBS), B36 (36 h, FBS) and D44 (44 h, foetal donkey serum, FDS). These results indicated that the maturation rate in group B36 was lower than group B44 (13.1% vs. 47.0%, p = .00) and group D44 (13.1% vs. 53.3%, p = .00). In conclusion, the quality of donkey COCs from OPU was higher than that from abattoir-derived ovaries, the suitable time of donkey in vitro maturation (IVM) was 44 h, and FBS could be replaced with FDS in donkey IVM medium.

Effect of Angelica Sinensis extract on the angiogenesis of preovulatory follicles (F1-F3) in late-phase laying hens

In order to form follicles and ovulate normally, there must be abundant blood vessels. Angelica sinensis (Oliv.) Diels (AS), as a traditional Chinese medicinal herb, has the effects of tonifying the blood and activating the blood circulation. However, the effect of AS on angiogenesis in hen-follicles remains to be discovered. In this study, we identified vascular richness, granulosa layer thickness, expression of platelet endothelial cell adhesion molecule-1 (CD31) and the content of vascular endothelial growth factor A (VEGFA) in granulosa layers to elucidate the effect of AS extract on angiogenesis in preovulatory follicles (F1-F3) of late-phase laying hens (75 wk). Based on network pharmacology, we predicted beta-sitosterol, ferulic acid, and caffeic acid as the main active components of AS, and hypoxia-inducible factor-1α (HIF1α), vascular endothelial growth factor receptor 2 (VEGFR2) as hub targets of AS in angiogenesis. The intersection targets were enriched by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, and the hub targets were verified by immunofluorescence and western blot. Molecular docking of active components with hub targets was performed and verified in vitro. The results showed that AS extract promoted angiogenesis in preovulatory follicles and increased granulosa cell layer thickness, CD31 expression and content of VEGFA. Experiments in vitro and in vivo demonstrated that AS extract promoted the expression of HIF1α and VEGFA, up-regulated the phosphorylation levels of VEGFR2. These results further demonstrated the reliability of molecular docking and network pharmacology findings. In summary, AS extract can promote angiogenesis in the preovulatory follicles in late-phase laying hens.

A Novel SNP in the Promoter Region of IGF1 Associated With Yunshang Black Goat Kidding Number via Promoting Transcription Activity by SP1

IGF1, a member of the insulin-like growth factor (IGF) superfamily, is also known as the growth-promoting factor (somatomedin C). IGF1 is involved in vertebrate growth and development, immunity, cell metabolism, reproduction, and breeding. However, there are relatively few studies on the relationship between IGF1 and goat reproduction. In this study, a new transcription factor SP1 bound to the IGF1 g. 64943050T>C promoted granulosa cell (GC) proliferation. A mutation g.64943050T>C located in the promoter region of IGF1 was identified. Association analysis revealed that the kidding number in the first and second litters and the average number of first three litters of the CC genotype (2.206 ± 0.044, 2.254 ± 0.056, and 2.251 ± 0.031) were significantly higher than those in the TC genotype (1.832 ± 0.049, 1.982 ± 0.06, and 1.921 ± 0.034) and TT genotype (1.860 ± 0.090, 1.968 ± 0.117, and 1.924 ± 0.062) (p < 0.05). The kidding number in the third litter of the CC genotype (2.355 ± 0.057) was significantly higher than that in the TT genotype (2.000 ± 0.107) (p < 0.05). Then, the function of this mutation was validated by the dual-luciferase reporter assay and EMSA. The results showed that the luciferase activity of IGF1-mutant-C was significantly higher than that of IGF1-Wild-T (p < 0.05). The EMSA also showed that the binding ability of IGF1-mutant-C was higher than that of IGF1-Wild-T (p < 0.05). Subsequently, the transcription factor SP1 was predicted to bind to the mutation of IGF1 (g.64943050T>C). Overexpression of SP1 promotes the expression of IGF1 in the primary granulosa cells (GCs). The results of the CCK-8 assay and the expression of GC proliferation factors (CDK4, cyclin D1, and cyclin D2) demonstrated that SP1 promoted GC proliferation by regulating IGF1 expression. Our results suggested that the IGF1 g.64943050T>C was significantly associated with the kidding number of Yunshang black goats, and SP1 as a transcription factor of IGF1 binding to the mutation T>C regulated the expression of IGF1. Furthermore, SP1 promoted goat GC proliferation by regulating the expression of IGF1, which provides a new insight for the goat fertility trait.

Pleiotropic Effects of IGF1 on the Oocyte

A woman’s endocrine system plays a crucial role in orchestrating cellular interactions throughout her life. The growth hormone (GH) and insulin-like growth factor (IGF) system appears to impact crucial reproductive events and cell types of the ovary, such as granulosa cells, theca cells, and oocytes. Further, IGF1 is a cornerstone during embryonic development and influences predominantly developing and pre-antral follicles. In this commentary, we will emphasize the pleiotropic effects of IGF1 on physiological processes inside the egg. Herein, we will provide a brief overview on IGF1 related cell signal transduction pathways during the maturation and aging of oocytes. We aim to elucidate from a molecular and biochemical point of view if IGF1 in women with metabolic imbalances such as obesity or diabetes could be used in clinics as a novel, reliable estimator for the developmental competence of an oocyte.

Differential expression of FSHR and LHR genes and proteins during development of rabbit ovarian follicles

The development of an ovarian follicle is a complex process at the cellular and molecular level that is mainly regulated by follicle-stimulating hormone receptor (FSHR) and luteinizing hormone receptor (LHR). To elucidate the contribution of these receptors to ovarian follicle development, it is necessary to determine their expression profiles during this biological process. Therefore, this study aimed to investigate the relationship between ovarian development pattern and the differential ovarian expression pattern of FSHR and LHR genes as well as proteins at different developmental stages. Ovaries were collected from 30 New Zealand rabbits at day 0 (birth), week 2 (neonate), week 4 (cub), week 16 (maturity), and day 18 pregnancy. Ovarian histology, and gene as well as protein expression were determined using light microscopy, real-time PCR and western blotting, respectively. The results showed that the expression levels of FSHR mRNA and protein increased coincidently with age and the growth of ovarian follicles. The levels of LHR mRNA and protein remained low from the day of birth until week 4 and became significantly higher by week 16 coinciding with appearance of growing and antral follicles, which have a defined thecal layer. FSHR gene and protein expression decreased with pregnancy, whereas LHR increased, reaching a peak level during pregnancy. It can be concluded that changes in FSHR and LHR gene and protein expression could be related to the growth and development of follicles, indicating the regulatory role for these receptors in rabbit folliculogenesis.

miRNA expression analysis of the sheep follicle during the prerecruitment, dominant, and mature stages of development under FSH stimulation

Follicle stimulating hormone (FSH) has been widely reported to influence ovarian follicular development, and miRNAs play a significant role in mammalian follicular development by regulating their target genes. Therefore, it is of interest to explore the roles of miRNAs in sheep follicular development during FSH stimulation. In the current study, we constructed miRNA expression profiles of small follicles (SFs, prerecruitment stage), medium follicles (MFs, dominance stage), and large follicles (LFs, maturation stage). Three and 50 significant differentially expressed miRNAs (DEMs) were identified in the MF vs. SF and LF vs. SF comparisons, respectively, and none were identified in the LF vs. MF comparison. Oar-miR-10a was significantly downregulated in MFs compared with SFs. In LFs compared with SFs, miR-212-3p, miR-212-5p and miR-202-5p were significantly upregulated, and miR-27a-3p, miR-181a-5p, miR-204-5p, and miR-182-5p were significantly downregulated. Furthermore, we predicted the target genes of significant DEMs and performed functional enrichment analyses of these target genes. Analyses of KEGG pathways and GO terms showed that the putative target genes were significantly enriched in ovarian steroidogenesis, glutathione metabolism, positive regulation of cell differentiation, positive regulation of cell development, and cellular response to oxygen-containing compounds. Analyses of miRNA-gene regulatory networks suggested that miR-181a-5p-CYP11A1, (miR-27a-3p and miR-129-5p)-LDLR, (miR-212-3p and miR-212-5p)-EFNA5, (miR-181a-5p, miR-182-5p, and miR-27a-3p)-INHBA, and miR-182-5p-SOD2 might be involved in follicular development. The present study provides basic data and suggests research directions for further exploration of the roles of miRNAs in sheep follicular development under FSH stimulation.

Effects of P4 Antagonist RU486 on VEGF and Its Receptors' Signaling during the In Vivo Transition from the Preovulatory to Periovulatory Phase of Ovarian Follicles

The development of an adequate blood vessel network is crucial for the accomplishment of ovarian follicle growth and ovulation, which is necessary to support the proliferative and endocrine functions of the follicular cells. Although the Vascular Endothelial Growth Factor (VEGF) through gonadotropins guides ovarian angiogenesis, the role exerted by the switch on of Progesterone (P4) during the periovulatory phase remains to be clarified. The present research aimed to investigate in vivo VEGF-mediated mechanisms by inducing the development of periovulatory follicles using a pharmacologically validated synchronization treatment carried out in presence or absence of P4 receptor antagonist RU486. Spatio-temporal expression profiles of VEGF, FLT1, and FLK1 receptors and the two major MAPK/ERKs and PI3K/AKT downstream pathways were analyzed on granulosa and on theca compartment. For the first time, the results demonstrated that in vivo administration of P4 antagonist RU486 inhibits follicular VEGF receptors' signaling mainly acting on the theca layer by downregulating the activation of ERKs and AKTs. Under the effect of RU486, periovulatory follicles' microarchitecture did not move towards the periovulatory stage. The present evidence provides new insights on P4 in vivo biological effects in driving vascular and tissue remodeling during the periovulatory phase.

Fatty Acid Profile of Blood Plasma at Mating and Early Gestation in Rabbit

The aim of this study was to analyse the fatty acid (FA) profile of blood plasma at mating and 72 hpm by gas chromatography. Moreover, the correlation between FA and ovulation rate, normal embryos and compacted morulae was estimated. Palmitic, linoleic, oleic and stearic were the highest FA concentrations at mating and 72 hpm. Most long chain saturated and PUFA were higher at 72 hpm than at mating, while MUFA were higher at mating. SFA, MUFA and PUFA were high and positively correlated. Correlation was 0.643 between MUFA at mating and ovulation rate, and 0.781 between MUFA and normal embryos, respectively. Compacted morulae were slightly correlated with SFA at mating (0.465). In conclusion, the FA profile of plasma varies depending on the reproductive cycle of the rabbit female, adapting to energetic requirements at mating and early gestation. Moreover, positive correlations are found between fatty acids and ovulation rate and embryo development and quality.

Effects of bone morphogenetic protein 4, gremlin, and connective tissue growth factor on estradiol and progesterone production by bovine granulosa cells

Bone morphogenetic proteins (BMPs) are members of the transforming growth factor-β family of proteins that have been implicated in the paracrine regulation of granulosa cell (GC) function, but whether responses to BMPs change with follicular size or interact with connective tissue growth factor (CTGF) or BMP antagonists (e.g., gremlin [GREM]) to directly affect GC function of cattle is unknown. Therefore, to determine the effects of BMP4 on proliferation and steroidogenesis of GCs and its interaction with GREM or CTGF, experiments were conducted using bovine GC cultures. In vitro, BMP4 (30 ng/mL) inhibited (P < 0.05) follicle-stimulating hormone (FSH) plus insulin-like growth factor 1 (IGF1)-induced progesterone and estradiol production by large- and small-follicle GCs, but the inhibitory effect of BMP4 on estradiol production was much more pronounced in large-follicle GCs. In small-follicle GCs, BMP4 had no effect (P > 0.10) on IGF1-induced proliferation, but GREM inhibited (P < 0.05) cell proliferation and estradiol and progesterone production in IGF1 plus FSH-treated GCs. In large-follicle GCs, BMP4 (10 to 30 ng/mL) increased (P < 0.05) GC numbers and GREM (100 ng/mL) blocked this effect. In large-follicle GCs, CTGF inhibited (P < 0.05) FSH plus IGF1-induced progesterone and estradiol production, and CTGF blocked the stimulatory effect of BMP4 on GC proliferation. These results indicate that BMP4, GREM, and CTGF inhibit GC aromatase activity and progesterone production. Also, the stimulatory effect of BMP4 on GC proliferation and the inhibitory effects of BMP4 on GC steroidogenesis are more pronounced in large vs. small follicles.

Effects of in vitro exposure of sheep ovarian tissue to zearalenone and matairesinol on preantral follicles

The aim of this study was to evaluate the effect of 1 µmol/l zearalenone (ZEN) and 1 µmol/l matairesinol (MAT), alone or in combination, on the morphology of in vitro-cultured ovarian preantral follicles. Ovaries from four adult sheep were collected at a local slaughterhouse and fragmented, and the ovarian pieces were submitted to in vitro culture for 3 days in the presence or absence of the test compounds. The morphology of primordial and primary follicles was impaired by ZEN. The plant lignan MAT alone did not maintain the morphology of the ovarian follicles; its combination with ZEN counteracted the negative effects observed when follicles were cultured in the presence of the mycotoxin alone. However, MAT was not able to promote the in vitro development of the ovarian follicles.

Bone Marrow-Derived Mesenchymal Stem Cells Reverse Radiotherapy-Induced Premature Ovarian Failure: Emphasis on Signal Integration of TGF-β, Wnt/β-Catenin and Hippo Pathways

Radiotherapy is an indispensable cancer treatment approach. However, it is associated with hazardous consequences on multiple organs characterized by insidious worsening severity over time. This study aimed to examine the potential therapeutic effects of bone marrow mesenchymal stem cells (BM-MSCs) in radiation-induced premature ovarian failure (POF). Exposing female rats to 3.2 Gy whole-body ϒ-rays successfully induced POF. One week later, a single intravenous injection of BM-MSCs (2*106) cells was administered. BM-MSCs perfectly home to the damaged ovaries, enhanced ovarian follicle pool, and preserved the ovarian function manifested by restoring serum estradiol and follicle stimulating hormone levels, besides, rescuing the fertility outcomes of irradiated rats. These events have been associated with inhibiting ovarian apoptosis (Bax/Bcl2, caspase 3) and enhancing proliferation (PCNA). Interestingly, BM-MSCs reversed the inhibition of ovarian FOXO3 expression induced by radiation which resulted in increased primordial follicles stock. Moreover, BM-MSCs recovered the suppressed folliculogenesis process induced by radiation through upregulating FOXO1, GDF-9, and Fst genes expression accompanied by downregulating TGF-β which enhanced granulosa cells proliferation and secondary follicle development. Mechanistically, BM-MSCs miRNAs epigenetically upregulate Wnt/β-catenin and Hippo signaling pathways which are implicated in ovarian follicles growth and maturation. Therefore, BM-MSCs presented a ray of hope in the treatment of radiation-associated POF through genetic and epigenetic modulation of the integrated TGF-β, Wnt/β-catenin, and Hippo pathways which control apoptosis, proliferation, and differentiation of ovarian follicles.

Pluripotency and Growth Factors in Early Embryonic Development of Mammals: A Comparative Approach

The regulation of early events in mammalian embryonic development is a complex process. In the early stages, pluripotency, cellular differentiation, and growth should occur at specific times and these events are regulated by different genes that are expressed at specific times and locations. The genes related to pluripotency and cellular differentiation, and growth factors that determine successful embryonic development are different (or differentially expressed) among mammalian species. Some genes are fundamental for controlling pluripotency in some species but less fundamental in others, for example, Oct4 is particularly relevant in bovine early embryonic development, whereas Oct4 inhibition does not affect ovine early embryonic development. In addition, some mechanisms that regulate cellular differentiation do not seem to be clear or evolutionarily conserved. After cellular differentiation, growth factors are relevant in early development, and their effects also differ among species, for example, insulin-like growth factor improves the blastocyst development rate in some species but does not have the same effect in mice. Some growth factors influence genes related to pluripotency, and therefore, their role in early embryo development is not limited to cell growth but could also involve the earliest stages of development. In this review, we summarize the differences among mammalian species regarding the regulation of pluripotency, cellular differentiation, and growth factors in the early stages of embryonic development.

Transcriptome analysis of sheep follicular development during prerecruitment, dominant, and mature stages after FSH superstimulation

Sheep is usually a monovular animal; superovulation technology is used to increase the number of offspring per individual and shorten generation intervals. To date, mature FSH superstimulatory treatments have been successfully used in sheep breeding, but much remains unknown about genes, pathways, and biological functions involved in follicular development. Therefore, in this study, we performed transcriptome profiling of small follicles (SFs; 2-2.5 mm), medium follicles (MFs; 3.5-4.5 mm), and large follicles (LFs; > 6 mm) in Mongolian ewes after FSH superstimulation. Furthermore, we identified differentially expressed genes and performed Kyoto Encyclopedia of Genes and Genomes pathway and Gene Ontology enrichment analyses in 3 separate pairwise comparisons. We found that ovarian steroidogenesis was significantly enriched in the SFs versus MFs analysis; the associated genes, cytochrome P450 family 19 (CYP19) and Hydroxy-delta-5-steroid dehydrogenase 3 beta- and steroid delta-isomerase 1 (HSD3B1), were significantly upregulated. Moreover, proline metabolism, glutathione metabolism, and PPAR signaling pathways were significantly enriched in the LFs versus SFs analysis; the associated genes, glutamate-cysteine ligase modifier subunit (GCLM) and cystathionine gamma-lyase (CTH), were significantly upregulated, whereas peroxisome proliferator-activated receptor gamma (PPARγ) was significantly downregulated. In summary, our study provides basic data and possible biological direction to further explore the molecular mechanism of sheep follicular development after FSH superstimulation.

Weaned Sows with Small Ovarian Follicles Respond Poorly to the GnRH Agonist Buserelin

Simple Summary

This study evaluated the influence of mean ovarian follicle size and the season of weaning on the effectiveness of administering the GnRH agonist buserelin to synchronize ovulation in weaned sows. The results from 352 sows demonstrated that sows with small follicles (<0.5 cm in diameter) at treatment are poor responders, a condition more frequent among sows weaned in summer–autumn than in those weaned in winter–spring.

Abstract

The GnRH agonist buserelin (GnRH), used to synchronize ovulation in weaned sows, attains only 70–80% effectivity, owing to several reasons of ovarian origin. This study evaluated in particular whether mean ovarian follicle size at treatment and the season of weaning are among those influencing GnRH responsiveness. The experiment was carried out in a temperate-region farm with 352 sows of 1–6 parities weaned either in winter–spring (WS, 174 sows) or in summer–autumn (SA, 178 sows). The sows were randomized into two groups: GnRH (10 µg of buserelin acetate at 86 h after weaning, 172 sows) and control (180 sows). The ovaries were transrectally scanned from weaning to ovulation and the sows clustered according to their mean follicular size at treatment time: small (<0.5 cm in diameter), medium (0.5 to 0.64 cm) and large (0.65 to 1.09 cm). In total, 88.33% of the GnRH-treated sows ovulated, with 82% of them within the expected time window (120–132 h after weaning). In contrast, 95.45% of the unresponsive sows had small follicles at the time of treatment and were mostly weaned in SA (20.45%) than in WS (4.76%). In conclusion, the conspicuous presence of sows having small ovarian follicles at treatment time compromises the efficiency of the GnRH agonist buserelin to synchronize ovulation in weaned sows, which occurs more frequently in summer–autumn weaning.

[Equine chorionic gonadotrophin: Biology and veterinary use]

The pituitary gonadotrophins follicle-stimulating hormone (FSH) and luteinizing hormone (LH) play a prominent role in the control of gonadal functions. Therefore, their use in the treatment of fertility disorders (e. g. anovulatory anestrus) as well as in biotechnology (e. g. superovulation, hormone programs for cycle synchronization) is of substantial interest. Preparations of FSH or LH are relatively expensive due to the laborious extraction from pituitary tissue and are therefore reserved for special indications. In primates and equids, the chorionic epithelium expresses an LH-like molecule (chorionic gonadotrophin, CG). Equine CG (eCG) selectively binds to LH receptors in equids. In all other domestic mammalian species, equine CG (eCG) shows an extraordinarily high FSH activity in addition to its LH activity ("dual activity"). Since its market launch, this has therefore gained considerable importance as a comparatively inexpensive FSH analogue, mainly for use in ruminants and pigs. In contrast to the human CG (hCG), which may be isolated non-invasively from the urine of pregnant women and is widely used as LH analogue, eCG must be extracted from the blood of pregnant donor mares, as eCG concentrations in urine are only minimal. Following reports of deaths and suffering of donor mares associated with eCG collection in South American settings, the current practice of eCG production has given rise to increasing public criticism. This has recently led to calls for a general production ban. Primary aim of this review is therefore to summarize the current state of knowledge concerning the properties and biology of this molecule, which is also highly interesting from the point of view of basic science.

Selection of fewer dominant follicles in Trio carriers given GnRH antagonist and luteinizing hormone action replaced by nonpulsatile human chorionic gonadotropin†

Studying selection of multiple dominant follicles (DFs) in monovulatory species can advance our understanding of mechanisms regulating selection of single or multiple DFs. Carriers of the bovine high fecundity Trio allele select multiple DFs, whereas half-sib noncarriers select a single DF. This study compared follicle selection during endogenous gonadotropin pulses versus during ablation of pulses with Acyline (GnRH antagonist) and luteinizing hormone (LH) action replaced with nonpulsatile human chorionic gonadotropin (hCG) treatment in Trio carriers (n = 28) versus noncarriers (n = 32). On Day 1.5 (Day 0 = ovulation), heifers were randomized: (1) Control, untreated; (2) Acyline, two i.m. doses (Days 1.5 and D3) of 3 μg/kg; (3) hCG, single i.m. dose of 50 IU hCG on Day 1.5 followed by daily doses of 100 IU; and (4) Acyline + hCG. Treatments with nonpulsatile hCG were designed to replace LH action in heifers treated with Acyline. Acyline treatment resulted in cessation of follicle growth on Day 3 with smaller (P < 0.0001) maximum follicle diameter in Trio carriers (6.6 ± 0.2 mm) than noncarriers (8.7 ± 0.4 mm). Replacement of LH action (hCG) reestablished follicle diameter deviation and maximum diameter of DFs in both genotypes (8.9 ± 0.3 mm and 13.1 ± 0.5 mm; P < 0.0001). Circulating follicle stimulating hormone (FSH) was greater in Acyline-treated than in controls. Finally, Acyline + hCG decreased (P < 0.0001) the number of DFs from 2.7 ± 0.2 to 1.3 ± 0.2 in Trio carriers, with most heifers having only one DF. This demonstrates the necessity for LH in acquisition of dominance in Trio carriers (~6.5 mm) and noncarriers (~8.5 mm) and provides evidence for a role of GnRH-induced FSH/LH pulses in selection of multiple DFs in Trio carriers and possibly other physiologic situations with increased ovulation rate.

Functional response of systemic and intrafollicular placental growth factor in cycling mares

The aim of the study was to assess the physiological reference values for systemic and intrafollicular placental growth factor (PlGF) concentrations in different categories of follicular sizes in cycling mares, according to progesterone (P4) and oestradiol (E2) patterns. Sixty ovaries were taken after slaughter from 30 clinically healthy mares. Regarding their size, the follicles were classified into three different categories, i.e. small (20-30 mm), medium-sized (31-40 mm) and large (≥41 mm), and follicular fluid (FF) was sampled from each single follicle. Intrafollicular PlGF concentrations were significantly increased in larger and medium-sized follicles compared to small follicles, and their values were 1.48 and 1.36 times higher than the systemic values, respectively. On the other hand, systemic PlGF concentrations were 1.3 times higher than those in the FF of follicles of small size. Intrafollicular P4 concentrations were significantly higher in larger follicles than in small ones, and their concentrations were 6.74 and 3.42 times higher than the systemic values, respectively. Intrafollicular E2 concentrations were significantly higher in large and medium-sized follicles than in follicles of small size, and their concentrations were 21.1, 15.4 and 8.35 times higher than the systemic values, respectively. Intrafollicular and systemic PlGF concentrations were strongly and positively correlated; nevertheless, no correlations between intrafollicular and systemic steroid hormones, PlGF and follicle diameters, PlGF and E2, or PlGF and P4 were observed. This represents the first study to characterise systemic and intrafollicular PlGF concentrations in cycling normal mares, providing evidence that the bioavailability of this factor in follicles of medium and large sizes was higher than in small follicles, independently of steroid hormone concentrations. Further studies are needed to assess the presumable implications of PlGF in follicular angiogenesis in mares, similar to those already observed in women and primates.

The potential function of endometrial-secreted factors for endometrium remodeling during the estrous cycle

Uterine has a pivotal role in implantation and conceptus development. To prepare a conducive uterine condition for possibly new gestation during the estrous cycle, uterine endometrium undergoes dramatic remodeling. In addition, angiogenesis is an indispensable biological process of endometrium remodeling. Furthermore, essential protein expressions related to important biological processes of endometrium remodeling, which are vascular endothelial growth factor (VEGF), myoglobin (MYG), collagen type IV (COL4), fucosyltransferase IV (FUT4), and cysteine-rich protein 2 (CRP2), were detected in the endometrial tissue reported in many previous studies and recently discovered in histotroph substrates during the estrous cycle. Those proteins, which are liable for provoking new vessel development, cell proliferation, cell adhesion, and cell migration, were expressed higher in the histotroph during the luteal phase than follicular phase. Histotroph proteins considerably contribute to endometrium remodeling during the estrous cycle. To that end, the following review will discuss and highlight the relevant information and evidence of the uterine fluid proteins as endometrial-secreted factors that adequately indicate the potential role of the uterine secretions to be involved in the endometrial remodeling process.

Comparison of the sequences and expression levels of genes related to follicular development and atresia between prolific and nonprolific goat breeds

This study investigated the variations of the nucleotide sequences and ovarian expression levels of genes related to follicular development and atresia in prolific Jintang black goats and nonprolific Tibetan goats. Eight genes, FSHB, LHB, FSHR, LHCGR, ESR2, B4GANT2, BCL2 and BAX, were examined using reverse transcription‐polymerase chain reaction and quantitative real‐time PCR. The results showed that the nucleotide and deduced amino acid sequences of the LHB and BAX genes were not different, but there was one base change in the FSHR genes between the two breeds. There was one base change in the FSHB gene, which resulted in one amino acid substitution; there were nine base changes in the LHCGR gene, which resulted in five amino acid substitutions; and there were six base changes in the B4GANT2 gene, which resulted in four amino acid substitutions. The expression levels of the FSHR, LHCGR, ESR2, B4GANT2, BCL2 and BAX genes in the ovaries were not different between the two breeds. The plasma concentrations of FSH were not different, but the plasma concentrations of LH, P₄ and E₂ were lower in prolific Jintang black goats than in nonprolific Tibetan goats (P ˂ 0.05) at 40 hr after removal of the Controlled Internal Drug Release Devices. These results provide some foundations elucidating the endocrine and molecular mechanisms controlling ovulation rate in goats, but these need to be further verified.

Proteomic Analysis of Porcine Pre-ovulatory Follicle Differentiation Into Corpus Luteum

The luteinization of the follicular cells, following a LH surge, causes extensive molecular and structural changes in preovulatory follicles (POF) that lead to ovulation and ultimate formation of the corpus luteum (CL). The objective of this study was to identify proteins expressed in porcine POF before the LH surge and a new CL formed, 2-3 days after ovulation, and evaluate proteome changes associated with formation of the CL from a follicle. We used 2D-gel electrophoresis-based proteomics and tandem mass spectrometry followed by a functional analysis using Ingenuity Pathway analysis (IPA) to evaluate functional pathways associated with the luteinization process. Protein lysates were prepared from isolated POFs and from the newly formed CL. A total of 422 protein spots were identified in both structures. A total of 15 and 48 proteins or their proteoforms were detected only in the POFs and CL, respectively. An IPA analysis of a POF proteome showed that most of the follicular proteins were involved in cellular infiltration, endoplasmic stress responses, and the protein ubiquitination pathway. Most of the early luteal proteins were associated with steroid metabolism, cell death and survival, free radical scavenging, and the protein ubiquitination pathway. A comparison of a follicular proteome with that of an early luteal proteome revealed that 167 identified proteins or their proteoforms were differentially regulated between POFs and the newly formed CL (p < 0.05 and a fold change of >1.8). Proteins that were significantly more abundant in follicles included cAMP-dependent protein kinase, histone binding protein RBBP4, reticulocalbin, vimentin, and calumenin; more abundant luteal proteins included albumin, farnesyl diphosphate synthase, serine protease inhibitors, elongation factor-1, glutaredoxin, and selenium-binding protein. Proteins that were significantly altered with luteal formation were found to be associated with cholesterol biosynthesis, cell death and survival, and acute phase response. Moreover, upstream regulators of differentially abundant proteins in CL were identified that included insulin growth factor-1, sterol regulatory element-binding transcription factor-1, and nuclear factor erythroid-derived 2. We have identified novel proteins that advance our understanding of (1) processes associated with differentiation of POFs into the CL, (2) possible mechanisms of luteal cell survival, and (3) pathways regulating steroidogenesis in the newly formed CL.

Insulin promotes preantral follicle growth and antrum formation through temporal expression of genes regulating steroidogenesis and water transport in the cat

The aims of the present study were to determine the effects of insulin, invitro, on: (1) the viability and growth of domestic cat ovarian follicles; (2) mRNA expression of genes regulating steroidogenesis (cytochrome P450 family 17 subfamily, A polypeptide 1 (Cyp17a1), cytochrome P450 family 19 subfamily, A polypeptide 1 (Cyp19a1) and steroidogenic acute regulatory protein (Star)) and water transport (aquaporins (AQPs) Aqp1, Aqp3, Aqp7, Aqp9); and (3) steroid production (17β-oestradiol (E2), progesterone (P4), androstenedione (A4)). Cat secondary follicles were isolated from ovarian cortices and cultured in 0 (Control), 1 or 10µgmL-1 insulin for 14 days (Day 0=culture onset). Follicle and oocyte viability (based on neutral red staining), diameter and antrum formation were assessed every 72h and at the end of incubation (Day 14). Expression of steroidogenic and water transport genes was evaluated on Days 0, 6 and 12, and E2, P4 and A4 concentrations in the culture medium were determined on Day 12. By Day 14, 1 and 10µgmL-1 insulin had significantly promoted (P<0.05) both antrum formation in a mean (±s.e.m.) 26.9±9.0% and 78.0±10.0% of follicles respectively, and follicle growth (diameter 151.4±4.5 and 169.9±10.5µm respectively) compared with Control (antrum formation in 3.3±3.3% of follicles and follicle diameter 129.1±6.6µm). High insulin (10µgmL-1) treatment increased follicle viability compared with Control (86.0±9.8% vs 38.1±10.9% respectively; P<0.05). However, insulin had no beneficial effect (P>0.05) on oocyte diameter. Cyp17a1 expression on Days 6 and 12 was higher (P<0.05) in follicles cultured in the low (1µgmL-1) compared with high (10µgmL-1) insulin treatment, with no significant difference between low or high insulin vs Control groups. Star expression was higher (P<0.01) in the low insulin compared with Control group on Day 6, but Star was undetectable in the high insulin group by Day 12. Compared with high insulin, low insulin increased (P<0.05) Aqp1 expression on Day 6, but there were no significant differences between these two groups on Day 12. In contrast, high insulin decreased (P<0.05) Aqp9 transcript levels compared with Control. Only P4 production was affected by insulin, with P4 concentrations in the medium being higher (P<0.05) in the low compared with high insulin and Control groups. In summary, the findings indicate that insulin promotes cat ovarian follicle growth and survival invitro, including enhanced antrum formation, with the likely mechanism involving temporal expression of Cyp17a1, Star and Aqp9 genes.

Detection of the effects and potential interactions of FSH, VEGFA, and 2-methoxyestradiol in follicular angiogenesis, growth, and atresia in mouse ovaries

Ovarian follicular development is a complex process that requires codevelopment of the perifollicular vascular network, which is closely regulated by angiogenic factors, gonadotropins, sex steroids, and their metabolites. To detect the effects of vascular endothelial growth factor 120 (VEGF120), follicle-stimulating hormone (FSH), and 2-methoxyestradiol (2ME2) on follicular angiogenesis during development and atresia, we treated sexually immature and mature female mice with VEGF120, FSH, 2ME2, and FSH receptor (FSHR) antagonist singly or in combination via intraperitoneal injection. The number of follicles and their perifollicular angiogenesis and atresia rates at different developmental stages were examined in paraffin sections after hematoxylin and eosin staining. The results showed that the exogenous factors have specific and precise effects on developmental, angiogenesis, and atresia processes in follicles of different sizes in mature and immature mice. Perifollicular angiogenesis was regulated by VEGFA and closely related to follicular development and atresia. 2ME2 affected angiogenesis through VEGFA and might regulate atresia directly. FSH might control VEGFA function via both transcriptional and posttranscriptional mechanisms because FSHR was required for achieving VEGFA functions at all the follicular development stages. The present study presents insights into the mechanisms of FSH, 2ME2, and VEGFA in follicular development and disorders and provides a foundation for the development of new therapeutic strategies.

Effects of plane of nutrition and arginine on ovarian follicles in non-pregnant sheep: Cell proliferation, and expression of endothelial nitric oxide and its receptor

The aim of this study was to investigate the role of the nitric oxide (NO) system in ovarian function, by determining if arginine (Arg) supplementation impacts follicle number, cell proliferation, and expression of the NO system members in nutritionally compromised ewes. Ewes were randomly assigned into maintenance (C, 100% requirements), excess (O; 2xC), or restricted (U; 0.6xC) diets 8 weeks prior to Arg treatment. Ewes were individually fed twice daily with pelleted diets. Ewes from each nutritional group were randomly assigned to one of two treatments: saline or Arg, which was initiated on day 0 of the estrous cycle and administered 3 times per day. Ovaries were collected at the early-luteal, mid-luteal and late-luteal/follicular phases of the estrous cycle to determine 1) the number of surface follicles, 2) follicle cell proliferation marked by Ki67 protein expression, and 3) expression of endothelial nitric oxide (eNOS; NOS3) and soluble guanylyl cyclase beta (sGC; GUCY1B3) protein and mRNA in granulosa (G) and theca (T) layers using immunohistochemistry followed by image analysis and qPCR, respectively. During nutritional treatment, C maintained body weight, O gained 6±1.2 kg, and U lost 14±1.3 kg. Our data show that: 1) Ki67 was expressed in all ovarian compartments, eNOS protein was detected in blood vessels of T and stroma, and sGC protein was detected in T cells, and blood vessels of T layer and other ovarian compartments; 2) plane of nutrition affected the number of surface follicles, and thus folliculogenesis, cell proliferation in the T layer, eNOS and sGC protein expression in T, and NOS3 and GUCY1B3 mRNA expression in G; 3) Arg treatment affected cell proliferation in G and T, eNOS and sGC protein expression in T, mRNA expression of NOS3 in T in all groups, and GUCY1B3 in G depending on the stage of the estrous cycle; and 4) G and T cell proliferation, and expression of eNOS and sGC protein in T was affected by the stage of the estrous cycle. Our data demonstrated that plane of nutrition and Arg are involved in the regulation of follicular functions in non-pregnant sheep.

Human amnion-derived mesenchymal stem cell (hAD-MSC) transplantation improves ovarian function in rats with premature ovarian insufficiency (POI) at least partly through a paracrine mechanism

Background

Chemotherapy can induce premature ovarian insufficiency (POI) and reduce fertility in young female patients. Currently, there is no effective therapy for POI. Human amnion-derived mesenchymal stem cells (hAD-MSCs) may be a promising seed cell for regenerative medicine. This study investigated the effects and mechanisms of hAD-MSC transplantation on chemotherapy-induced POI in rats.

Methods

Chemotherapy-induced POI rat models were established by intraperitoneal injection of cyclophosphamide. Seventy-two female SD rats were randomly divided into control, POI, and hAD-MSC-treated groups. hAD-MSCs were labeled with PKH26 and injected into the tail veins of POI rats. To examine the underlying mechanisms, the differentiation of transplanted hAD-MSCs in the POI ovaries was analyzed by immunofluorescent staining. The in vitro expression of growth factors secreted by hAD-MSCs in hAD-MSC-conditioned media (hAD-MSC-CM) was analyzed by ELISA. Sixty female SD rats were divided into control, POI, and hAD-MSC-CM-treated groups, and hAD-MSC-CM was injected into the bilateral ovaries of POI rats. After hAD-MSC transplantation or hAD-MSC-CM injection, serum sex hormone levels, estrous cycles, ovarian pathological changes, follicle counts, granulosa cell (GC) apoptosis, and Bcl-2, Bax, and VEGF expression in ovaries were examined.

Results

PKH26-labeled hAD-MSCs mainly homed to ovaries after transplantation.

hAD-MSC transplantation reduced ovarian injury and improved ovarian function in rats with POI. Transplanted hAD-MSCs were only located in the interstitium of ovaries, rather than in follicles, and did not express the typical markers of oocytes and GCs, which are ZP3 and FSHR, respectively. hAD-MSCs secreted FGF2, IGF-1, HGF, and VEGF, and those growth factors were detected in the hAD-MSC-CM. hAD-MSC-CM injection improved the local microenvironment of POI ovaries, leading to a decrease in Bax expression and an increase in Bcl-2 and endogenous VEGF expression in ovarian cells, which inhibited chemotherapy-induced GC apoptosis, promoted angiogenesis and regulated follicular development, thus partly reducing ovarian injury and improving ovarian function in rats with POI.

Conclusions

hAD-MSC transplantation can improve ovarian function in rats with chemotherapy-induced POI at least partly through a paracrine mechanism. The presence of a paracrine mechanism accounting for hAD-MSC-mediated recovery of ovarian function might be attributed to the growth factors secreted by hAD-MSCs.

Ovarian extracellular MicroRNAs as the potential non-invasive biomarkers: An update

Through the reproductive system, it has been realized that the microRNAs (miRNAs) have emerged as one of the principal post-transcriptional gene regulators of the diverse developmental processes. The ovary, as a dynamic organ, co-ordinates follicle recruitment, selection, and ovulation, in which miRNAs play the central role almost in its all functions. Deregulation of these developmental procedures in ovary could lead to the ovarian dysfunction, infertility, decrease in the assisted reproductive treatment (ART) outcome, and death in some patients with ovarian cancer. In recent years, detection of ovarian extracellular miRNAs in body fluids such as follicular fluid and serum/plasma has opened a new era in the biomarker discovery field. Here through the present review, different aspects of the potential and proposed involvement of the extracellular miRNAs in both physiologic and pathologic contexts of the ovary have been discussed. Moreover, the researchers have addressed the relevant findings, challenges, and issues which associated with the extracellular miRNAs in the ovarian microenvironments to provide the better insight into understanding the molecular mechanisms which were involved in the pathophysiologic conditions. Finally, a comprehensive survey of the gaps has been discussed to hopefully shed new light and perspective on the development of the novel diagnostic and therapeutic platforms in the clinic.

GDF9-β promotes folliculogenesis in sheep ovarian transplantation onto the chick embryo chorioallantoic membrane (CAM) in cryopreservation programs

PURPOSE

Ovarian tissue (OT) cryopreservation is a treatment option for fertility preservation among young cancer patients. However, the procedure may involve a reduction in the GDF9-β expression and a delay in follicular growth after thawing and transplantation. The aim of this study was to evaluate whether supplementation of GDF9-β can compensate the reduction of this factor during the cryopresevation process and promote folliculogenesis after transplantation of thawed sheep ovarian tissue.

METHODS

Sheep OT was cryopreserved using two methods of vitrification and slow freezing. Fresh and thawed OTs were then transplanted onto chick embryo chorioallantoic membrane (CAM) and then divided into two groups based on the addition of GDF9-β to the grafted tissue. After 5 days of culture, both histological and immunohistological (Ki-67) assessments were performed to evaluate follicular structure, development, and proliferation. The fibrotic and necrotic areas were measured using MICROVISIBLE software.

RESULTS

Folliculogenesis took place in all culture groups, but was significantly improved only in the +GDF9-β cultured group. Also, better follicular structure was preserved in the aforementioned group (p < 0.05). When GDF9-β was supplemented to the culture medium, more neovascularization (p < 0.05) and better transplantation (p > 0.05) was observed. Furthermore, the areas of fibrosis and necrosis were lower in this group rather than the controls. Follicular proliferative activity was significantly higher only in the slow freezing +GDF9-β cultured group.

CONCLUSIONS

GDF9-β, as a stimulatory factor, not only promoted the folliculogenesis in the fresh ovarian transplant, but also compensated for its reduction during the cryopreservation process.

Active 3'-5' cyclic nucleotide phosphodiesterases are present in detergent-resistant membranes of mural granulosa cells

Lipids rafts are specialised membrane microdomains involved in cell signalling that can be isolated as detergent-resistant membranes (DRMs). The second messenger cyclic AMP (cAMP) has a central role in cell signalling in the ovary and its degradation is carried out by the phosphodiesterase (PDE) enzyme family. We hypothesised that PDEs could be functionally present in the lipid rafts of porcine mural granulosa cell membranes. PDE6C, PDE8A and PDE11A were detected by dot blot in the DRMs and the Triton-soluble fraction of the mural granulosa cells membrane and the cytosol. As shown by immunocytochemistry, PDEs showed clear immunostaining in mural granulosa cell membranes and the cytosol. Interestingly, cAMP-PDE activity was 18 times higher in the DRMs than in the Triton-soluble fraction of cell membranes and was 7.7 times higher in the cytosol than in the DRMs. cAMP-PDE activity in mural granulosa cells was mainly contributed by the PDE8 and PDE11 families. This study shows that PDEs from the PDE8 and PDE11 families are present in mural granulosa cells and that the cAMP-PDE activity is mainly contributed by the cytosol. In the cell membrane, the cAMP-PDE activity is mainly contributed by the DRMs. In addition, receptors for prostaglandin E2 and LH, two G-protein-coupled receptors, are present in lipid rafts and absent from the non-raft fraction of the granulosa cell membrane. These results suggest that in these cells, the lipid rafts exist as a cell-signalling platform and PDEs are one of the key enzyme families present in the raft.

Identification of Differentially Expressed Genes in Porcine Ovaries at Proestrus and Estrus Stages Using RNA-Seq Technique

Estrus is an important factor for the fecundity of sows, and it is involved in ovulation and hormone secretion in ovaries. To better understand the molecular mechanisms of porcine estrus, the expression patterns of ovarian mRNA at proestrus and estrus stages were analyzed using RNA sequencing technology. A total of 2,167 differentially expressed genes (DEGs) were identified (P ≤ 0.05, |log2  Ratio| ≥ 1), of which 784 were upregulated and 1,383 were downregulated in the estrus compared with the proestrus group. Gene Ontology (GO) enrichment indicated that these DEGs were mainly involved in the cellular process, single-organism process, cell and cell part, and binding and metabolic process. In addition, a pathway analysis showed that these DEGs were significantly enriched in 33 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including cell adhesion molecules, ECM-receptor interaction, and cytokine-cytokine receptor interaction. Quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) confirmed the differential expression of 10 selected DEGs. Many of the novel candidate genes identified in this study will be valuable for understanding the molecular mechanisms of the sow estrous cycle.

Placental Growth Factor Is Required for Ovulation, Luteinization, and Angiogenesis in Primate Ovulatory Follicles

Placental growth factor (PGF) is member of the vascular endothelial growth factor (VEGF) family of angiogenesis regulators. VEGFA is an established regulator of ovulation and formation of the corpus luteum. To determine whether PGF also mediates aspects of ovulation and luteinization, macaques received gonadotropins to stimulate multiple follicular development. Ovarian biopsies and whole ovaries were collected before (0 hours) and up to 36 hours after human chorionic gonadotropin (hCG) administration to span the ovulatory interval. PGF and VEGFA were expressed by both granulosa cells and theca cells. In follicular fluid, PGF and VEGFA levels were lowest before hCG. PGF levels remained low until 36 hours after hCG administration, when PGF increased sevenfold to reach peak levels. Follicular fluid VEGFA increased threefold to reach peak levels at 12 hours after hCG, then dropped to intermediate levels. To explore the roles of PGF and VEGFA in ovulation, luteinization, and follicular angiogenesis in vivo, antibodies were injected into the follicular fluid of naturally developed monkey follicles; ovariectomy was performed 48 hours after hCG, with ovulation expected about 40 hours after hCG. Intrafollicular injection of control immunoglobulin G resulted in no retained oocytes, follicle rupture, and structural luteinization, including granulosa cell hypertrophy and capillary formation in the granulosa cell layer. PGF antibody injection resulted in oocyte retention, abnormal rupture, and incomplete luteinization, with limited and disorganized angiogenesis. Injection of a VEGFA antibody resulted in oocyte retention and very limited follicle rupture or structural luteinization. These studies demonstrate that PGF, in addition to VEGFA, is required for ovulation, luteinization, and follicular angiogenesis in primates.

Characteristic of factors influencing the proper course of folliculogenesis in mammals

Folliculogenesis is the process of ovarian follicle formation,, taking presence during foetal period. During the follicular development, oogoniums undergo meiosis and oocytes are formed. In the ovaries of new born sows, primary and secondary follicles are present and, 90 days after birth, tertiary follicles appear. During development in the ovarian follicles growth of granulosa cells and differentiation of the thecal cells can be observed. A cavity filled with follicular fluid appears. Granulosa cells are divided into: mural cells and corona radiata, which together with the oocyte form the cumulus oophorus. Corona radiata cells, mural layers and oolemma contact each other by a network of gap junctions. Secreted from the pituitary gland, FSH and LH gonadotropin hormones act on receptors located in granular and follicular cells. In the postnatal life tertiary follicles and Graafian follicles are formed. When the follicle reaches a diameter of 1 mm, further growth depends on the secretion of gonadotropins. Mature ovarian follicles produce: progestins, androgens and oestrogens. The growth, differentiation and steroidogenic activity of ovarian follicles, in addition to FSH and LH, is also affected by prolactin, oxytocin, steroid and protein hormones, numerous proteins from the cytokine and interleukin family, metabolic hormones like insulin, glucocorticoids, leptin, thyroid hormones and growth hormones. Despite numerous studies, many processes related to folliculogenesis have not been discovered Learning the mechanisms regulating reproductive processes would allow to easily distinguish pathological processes and discover more and more genes and mechanisms of their expression in cells that build ovarian follicles.

Exposure to high ambient temperatures alters embryology in rabbits

High ambient temperatures are a determining factor in the deterioration of embryo quality and survival in mammals. The aim of this study was to evaluate the effect of heat stress on embryo development, embryonic size and size of the embryonic coats in rabbits. A total of 310 embryos from 33 females in thermal comfort zone and 264 embryos of 28 females in heat stress conditions were used in the experiment. The traits studied were ovulation rate, percentage of total embryos, percentage of normal embryos, embryo area, zona pellucida thickness and mucin coat thickness. Traits were measured at 24 and 48 h post-coitum (hpc); mucin coat thickness was only measured at 48 hpc. The embryos were classified as zygotes or two-cell embryos at 24 hpc, and 16-cells or early morulae at 48 hpc. The ovulation rate was one oocyte lower in heat stress conditions than in thermal comfort. Percentage of normal embryos was lower in heat stress conditions at 24 hpc (17.2%) and 48 hpc (13.2%). No differences in percentage of zygotes or two-cell embryos were found at 24 hpc. The embryo development and area was affected by heat stress at 48 hpc (10% higher percentage of 16-cells and 883 μm² smaller, respectively). Zona pellucida was thicker under thermal stress at 24 hpc (1.2 μm) and 48 hpc (1.5 μm). No differences in mucin coat thickness were found. In conclusion, heat stress appears to alter embryology in rabbits.

Genome-Wide SNP Signal Intensity Scanning Revealed Genes Differentiating Cows with Ovarian Pathologies from Healthy Cows

Hypoplasia and ovarian cysts are the most common ovarian pathologies in cattle. In this genome-wide study we analyzed the signal intensity of 648,315 Single Nucleotide Polymorphisms (SNPs) and identified 1338 genes differentiating cows with ovarian pathologies from healthy cows. The sample consisted of six cows presenting an ovarian pathology and six healthy cows. SNP signal intensities were measured with a genotyping process using the Axiom Genome-Wide BOS 1 SNPchip. Statistical tests for equality of variance and mean were applied to SNP intensities, and significance p-values were obtained. A Benjamini-Hochberg multiple testing correction reveled significant SNPs. Corresponding genes were identified using the Bovine Genome UMD 3.1 annotation. Principal Components Analysis (PCA) confirmed differentiation. An analysis of Copy Number Variations (CNVs), obtained from signal intensities, revealed no evidence of association between ovarian pathologies and CNVs. In addition, a haplotype frequency analysis showed no association with ovarian pathologies. Results show that SNP signal intensity, which captures not only information for base-pair genotypes elucidation, but the amount of fluorescence nucleotide synthetization produced in an enzymatic reaction, is a rich source of information that, by itself or in combination with base-pair genotypes, might be used to implement differentiation, prediction and diagnostic procedures, increasing the scope of applications for Genotyping Microarrays.