The pFSH dose affects the efficiency of in vivo embryo production in Santa Inês ewes

This study compared the follicular growth, superovulatory response, and in vivo embryo production after administering two doses of porcine follicle-stimulating hormone (pFSH) in Santa Inês ewes. The estrous cycle of 36 multiparous ewes was synchronized with the Day 0 protocol and superovulated with 133 mg (G133, n=18) or 200 mg (G200, n=18) of pFSH. Ultrasonographic evaluations of the ovaries were performed, ewes were mated and submitted to non-surgical embryo recovery. Viable blastocysts were stained with Nile Red and Hoechst. The G200 had a greater number of medium and large follicles, as well as a larger size of the third largest follicle. A total of 97.2% (35/36) of the ewes came into estrus and it was possible to transpose cervix in 80.6% (29/36). There were no effects of treatments in the response to superovulation, the proportion of ewes in which was possible to transpose the cervix, the number of corpora lutea, the number of anovulatory follicles, the proportion of ewes flushed with at least one recovered structure, number of recovered structures, number of viable embryos, viability rate, and recovery rate. The G200 ewes were in estrus for a longer period of time than the G133 ewes (54.0 ± 4.5 h vs. 40.3 ± 3.6 h) and produced more freezable embryos (6.5 ± 1.6 vs. 2.3 ± 0.7) than G133. Both doses promoted an efficient superovulatory response and did not affect embryonic lipid accumulation. The dose of 200 mg of pFSH showed greater potential to increase the superovulatory response, as it increased follicular recruitment and the recovery of freezable embryos.

Nonlinear relationship between gonadotropin total dose applied and live birth rates in non-PCOS patients: a retrospective cohort study

The purpose of this article is to explore the relationship between the total dose of follicle-stimulating hormone (FSH) applied during controlled ovulation stimulation and the live birth rates (LBRs) in non-PCOS population. Many studies have found no difference between the dose of FSH application and pregnancy outcomes such as clinical pregnancy rates after fresh embryo transfer. However, a recent large retrospective analysis found a negative correlation between live birth rates and increasing dose of FSH. It is still controversial about the association between FSH dose and LBRs. In addition, no studies have yet explored the nonlinear relationship between FSH and LBRs. This cohort study included a total of 11,645 patients who had accepted IVF/intracytoplasmic sperm injection (ICSI) at the second hospital of Hebei medical university between December 2014 to December 2019. PCOS was identified by Rotterdam PCOS criteria. We researched the association between FSH total dose and live birth rates (LBRs) using multivariate regression analysis. In addition, a model for nonlinear relationships based on a two-part linear regression was applied. The analysis of threshold effects indicated that LBR increased with every 1000 IU FSH when the concentration of FSH was lower than 1410 IU (OR 1.55, 95% CI [1.05, 2.28]); however, a negative association between FSH dose and LBR (OR 0.94, 95% CI [0.89, 0.99]) was found when the FSH total dose was higher than 1410 IU. It is worth noting that the relationship between LBR and FSH dose varied among patients of different ages (OR 0.92 vs 1.06, P for interaction < 0.05).

E2/ER signaling mediates the meiotic arrest of goat intrafollicular oocytes induced by follicle-stimulating hormone

The increased production of high-quality oocytes lies at the heart of the search to accelerate the reproduction of high-quality breeding livestock using assisted reproductive technology. Follicle-stimulating hormone (FSH) maintains the arrest of oocyte meiosis during early follicular development in vivo and promotes the synchronous maturation of nucleus and cytoplasm to improve oocyte quality. However, the mechanism by which FSH maintains meiotic arrest in oocytes is still not fully understood. Oocytes spontaneously resume meiosis once released from the arrested state. In this study, we isolated goat antral follicles with a diameter of 2.0-4.0 mm, cultured them in vitro either with or without added FSH, and finally collected the oocytes to observe their meiotic state. The results showed that FSH effectively inhibited the meiotic recovery of oocytes in follicles [4 h: control (n = 84) vs. with FSH (n = 86), P = .0115; 6 h: control (n = 86) vs. FSH (n = 85), P = 0.0308; and 8 h: control (n = 95) vs. FSH (n = 101), P = 0.0039]. FSH significantly inhibited the downregulation of natriuretic peptide receptor 2 (NPR2) expression and cyclic guanosine monophosphate (cGMP) synthesis during follicular culture in vitro (P < 0.05). Further exploration found that FSH promoted the synthesis of 17β-estradiol (E2) (P = .0249 at 4 h and P = .0039 at 8 h) and maintained the expression of the estrogen nuclear receptor ERβ, but not the estrogen nuclear receptor ERα during follicle culture in vitro (P = .0190 at 2 h, and P = .0100 at 4 h). In addition, E2/ER (estrogen nuclear receptors ERα and ERβ) mediated the inhibitory effect of FSH on the downregulation of NPR2 expression and cGMP synthesis, ultimately preventing the meiotic recovery of oocytes (P < .05). In summary, our study showed that FSH-induced estrogen production in goat follicles, and the E2/ER signaling pathway, both mediated meiotic arrest in FSH-induced goat oocytes.

High initial FSH dosage reduces the number of available cleavage-stage embryos in a GnRH-antagonist protocol: Real-world data of 8,772 IVF cycles from China

To evaluate the relationship between the initial follicle stimulating hormone (FSH) dose and the number of available cleavage-stage embryos in in vitro fertilization (IVF) cycles.We included 8772 fresh IVF cycles using a GnRH antagonist protocol at the Genetic and Reproductive Institution of Chongqing, P. R. China, from January 2016 to June 2021.Univariate linear regression was used to evaluate the associations between the initial FSH dosage (≤ 150, 187.5-200, 225, 250, or 300 IU) with the number of available cleavage-stage embryos on day 3. A two-factor linear regression model was applied to calculate the threshold effect of the initial FSH dosage on the number of available cleavage-stage embryos based on a smoothing plot. The initial FSH dose was negatively correlated with the number of available cleavage-stage embryos, independent of female age, body mass index, infertility factors, duration of infertility, anti-Müllerian hormone and basal FSH levels, antral follicle count and the proportions of patients with poor ovarian response or polycystic ovarian syndrome. Using a two-factor linear regression model, we calculated the inflection point to be 200 IU of FSH. The relationship between the initial FSH dose and the number of available cleavage-stage embryos was nonlinear. The initial FSH dose was negatively associated with the number of available cleavage-stage embryos when the initial FSH dose was > 200 IU. Therefore, clinicians should try to avoid unnecessarily increasing the initial FSH dose.

Single-cell DNA methylation sequencing reveals epigenetic alterations in mouse oocytes superovulated with different dosages of gonadotropins

BACKGROUND

Epigenetic abnormalities caused by superovulation have recently attracted increasing attention. Superovulation with exogenous hormones may prevent oocytes from establishing an appropriate epigenetic state, and this effect may extend to the methylation programming in preimplantation embryos, as de novo DNA methylation is a function of developmental stage of follicles and oocyte size. Follicle-stimulating hormone (FSH) and human menopausal gonadotropin (hMG) are common gonadotropins used for superovulation, and appropriate concentrations of these gonadotropins might be necessary. However, no systematic study on the effects of DNA methylation alterations in oocytes associated with superovulation with different dosages of FSH/hMG at the single-cell level has yet been reported. In the current study, different dosages of FSH/hMG combined with human chorionic gonadotropin (hCG) were used in female mice to generate experimental groups, while naturally matured oocytes and oocytes superovulated with only hCG were respectively used as controls. Single-cell level DNA methylation sequencing was carried out on all these matured oocytes.

RESULTS

In this study, we revealed that the genome-wide methylation pattern and CG methylation level of the maternal imprinting control regions of all mature oocytes were globally conserved and stable. However, methylation alterations associated with superovulation were found at a specific set of loci, and the differentially methylated regions (DMRs) mainly occurred in regions other than promoters. Furthermore, some of the annotated genes in the DMRs were involved in biological processes such as glucose metabolism, nervous system development, cell cycle, cell proliferation, and embryo implantation and were altered in all dosages of FSH/hMG group (for example, Gfod2 and SYF2). Other genes were impaired only after high gonadotropin dosages (for instance, Sox17 and Phactr4).

CONCLUSIONS

In conclusion, the current study addressed the effects of superovulation on DNA methylation from the perspective of different dosages of gonadotropins at the single-cell level. We found that the genome-wide DNA methylation landscape was globally preserved irrespective of superovulation or of the kind and dosage of gonadotropins used, whereas the methylation alterations associated with superovulation occurred at a specific set of loci. These observed effects reflect that superovulation recruits oocytes that would not normally be ovulated or that have not undergone complete epigenetic maturation. Our results provide an important reference for the safety assessment of superovulation with different dosages of gonadotropins. However, it should be noted that this study has some limitations, as the sample number and library coverage of analyzed oocytes were relatively low. Future studies with larger sample sizes and high-coverage libraries that examine the effects of superovulation on embryo development and offspring health as well as the underlying mechanisms are still needed.

Quality of common marmoset (Callithrix jacchus) oocytes collected after ovarian stimulation

The common marmoset (Callithrix jacchus) is an experimental animal that is considered suitable for the creation of next-generation human disease models. It has recently been used in the reproductive technology field. Oocytes can be effectively collected from female marmosets via ovarian stimulation with injections of follicle-stimulating hormone (FSH) and human chorionic gonadotropin (hCG). The oocytes, collected about 28 h after the hCG injection, include both premature oocytes and postmature (in vivo matured; IVO) oocytes, and the premature oocytes can be matured by in vitro culture (in vitro matured; IVM). Although IVM and IVO oocytes are equivalent in appearance at the MII stage, it remains unclear whether there are differences in their properties. Therefore, we investigated their in vitro fertilization and developmental capacities and cytoskeletal statuses. Our findings revealed that the IVM and IVO oocytes had similar fertilization rates but that no IVO oocytes could develop to the blastocyst stage. Additionally, IVO oocytes showed abnormal cytoskeletal formation. It is concluded that IVM oocytes maintain normal function, whereas IVO oocytes would be affected by aging and other factors when they remain for a long time in the ovary.

Subcutaneous ovarian tissue transplantation in nonhuman primates: duration of endocrine function and normalcy of subsequent offspring as demonstrated by reproductive competence, oocyte production, and telomere length

PURPOSE

The main purposes of the study were to investigate the endocrine function of ovarian tissue transplanted to heterotopic subcutaneous sites and the reproductive competence and telomere length of a nonhuman primate originating from transplanted tissue.

METHODS

Ovarian cortex pieces were transplanted into the original rhesus macaques in the arm subcutaneously, in the abdomen next to muscles, or in the kidney. Serum estradiol (E2) and progesterone (P4) concentrations were measured weekly for up to 8 years following tissue transplantation. A monkey derived from an oocyte in transplanted ovarian tissue entered time-mated breeding and underwent controlled ovarian stimulation. Pregnancy and offspring were evaluated. Telomere lengths and oocytes obtained following controlled ovarian stimulation were assessed.

RESULTS

Monkeys with transplants in the arm and abdomen had cyclic E2 of 100 pg/ml, while an animal with arm transplants had E2 of 50 pg/ml. One monkey with transplants in the abdomen and kidney had ovulatory cycles for 3 years. A monkey derived from an oocyte in transplanted tissue conceived and had a normal gestation until intrapartum fetal demise. She conceived again and delivered a healthy offspring at term. Controlled ovarian stimulations of this monkey yielded mature oocytes comparable to controls. Her telomere length was long relative to controls.

CONCLUSIONS

Heterotopic ovarian tissue transplants yielded long-term endocrine function in macaques. A monkey derived from an oocyte in transplanted tissue was reproductively competent. Her telomere length did not show epigenetically induced premature cellular aging. Ovarian tissue transplantation to heterotopic sites for fertility preservation should move forward cautiously, yet optimistically.

Activin Decoy Receptor ActRIIB:Fc Lowers FSH and Therapeutically Restores Oocyte Yield, Prevents Oocyte Chromosome Misalignments and Spindle Aberrations, and Increases Fertility in Midlife Female SAMP8 Mice

Women of advanced maternal age (AMA) (age ≥ 35) have increased rates of infertility, miscarriages, and trisomic pregnancies. Collectively these conditions are called "egg infertility." A root cause of egg infertility is increased rates of oocyte aneuploidy with age. AMA women often have elevated endogenous FSH. Female senescence-accelerated mouse-prone-8 (SAMP8) has increased rates of oocyte spindle aberrations, diminished fertility, and rising endogenous FSH with age. We hypothesize that elevated FSH during the oocyte's FSH-responsive growth period is a cause of abnormalities in the meiotic spindle. We report that eggs from SAMP8 mice treated with equine chorionic gonadotropin (eCG) for the period of oocyte growth have increased chromosome and spindle misalignments. Activin is a molecule that raises FSH, and ActRIIB:Fc is an activin decoy receptor that binds and sequesters activin. We report that ActRIIB:Fc treatment of midlife SAMP8 mice for the duration of oocyte growth lowers FSH, prevents egg chromosome and spindle misalignments, and increases litter sizes. AMA patients can also have poor responsiveness to FSH stimulation. We report that although eCG lowers yields of viable oocytes, ActRIIB:Fc increases yields of viable oocytes. ActRIIB:Fc and eCG cotreatment markedly reduces yields of viable oocytes. These data are consistent with the hypothesis that elevated FSH contributes to egg aneuploidy, declining fertility, and poor ovarian response and that ActRIIB:Fc can prevent egg aneuploidy, increase fertility, and improve ovarian response. Future studies will continue to examine whether ActRIIB:Fc works via FSH and/or other pathways and whether ActRIIB:Fc can prevent aneuploidy, increase fertility, and improve stimulation responsiveness in AMA women.

Role of Sirt3 in mitochondrial biogenesis and developmental competence of human in vitro matured oocytes

STUDY QUESTION

Does Sirt3 dysfunction result in poor developmental outcomes for human oocytes after in vitro maturation (IVM)?

SUMMARY ANSWER

Inefficient Sirt3 expression induced decreased mitochondrial DNA copy number and biogenesis, and therefore impaired the developmental competence of human IVM oocytes.

WHAT IS KNOWN ALREADY

Cytoplasmic immaturity in IVM oocytes may lead to reduced developmental competence. Mitochondrial dysfunction results in the accumulation of free radicals and leads to DNA mutations, protein damage, telomere shortening and apoptosis. SIRT3 (in the Sirtuin protein family) has emerged as a mitochondrial fidelity protein that directs energy generation and regulates reactive oxygen species scavenging proteins.

STUDY DESIGN, SIZE, DURATION

In vivo matured metaphase II (IVO-MII) oocytes and IVM-MII oocytes were donated by 324 infertile patients undergoing assisted reproductive technology cycles (12 patients for 60 IVO oocytes, and 312 patients for 403 IVM oocytes). Five oocytes each in the germinal vesicle (GV), IVM and IVO groups were compared with respect to mRNA levels for Sirt1-7 mRNA, and five samples at each developmental stage were analysed for Sirt3 mRNA. IVM-MII oocytes were injected with in vitro transcribed mRNA (n = 59) or small interfering RNA (siRNA) (n = 78). In human and mouse, IVM, mRNA-injection IVM, and siRNA-injection IVM groups (n = 5 each) were analysed for mitochondrial DNA copy number and abundance of Sirt3 and Pgc1α (an inducer of mitochondrial biogenesis) mRNAs. Human blastocysts in the IVO (n = 12), IVM (n = 9), mRNA-injection IVM (n = 13) and siRNA-injection IVM (n = 6) groups were used to generate embryonic stem cells (ESCs). In addition, 587 IVO-MII and 1737 IVM-MII oocytes from 83 mice were collected to compare the preliminary human oocyte data with another species.

PARTICIPANTS/MATERIALS, SETTING, METHODS

mRNA abundance was analysed by single-cell real-time PCR. Karyotyping of human embryos was performed with an array comparative genomic hybridization method, and that of ESCs by cytogenetic analysis. The function of the Sirt3 gene was investigated using siRNA and in vitro transcribed mRNA injection. Markers of ESCs were identified using immunofluorescence.

MAIN RESULTS AND THE ROLE OF CHANCE

A retrospective analysis revealed a higher spontaneous abortion rate (P < 0.01) and decrease in high quality embryo rate (P < 0.01) in patients with IVM versus controlled ovarian stimulation (COS) cycles. A decrease in abundance of Sirt3 mRNA (P < 0.01) and mitochondrial biogenesis (P < 0.05) were identified in human IVM compared with IVO oocytes. The developmental potential of human IVM-MII oocytes to the blastocyst stage was significantly reduced when Sirt3 mRNA was inhibited by siRNA (P < 0.05 versus IVM-MII group) but could be up-regulated by injection of Sirt3 mRNAs. Compared with IVO-MII group, comparable generation efficiency of human ESCs can be obtained using blastocysts from IVM-MII oocytes with Sirt3 mRNA injection. Sirt3 mRNA was significantly increased in mouse zygotes after IVF (P < 0.001 versus MII oocytes) but gradually declined until the blastocyst stage. In mice, lower Sirt3 mRNA levels were observed IVM-MII oocytes and preimplantation embryos compared with in vivo controls, and mitochondrial biogenesis and the developmental efficiency from oocytes to blastocyst were affected by the abundance of Sirt3 mRNA in accordance with human. Therefore a similar role for Sirt3 mRNA in IVM-MII oocytes was observed in mouse and human.

LIMITATIONS, REASONS FOR CAUTION

The couples in the study had a variety of different simple and complex factors causing infertility. Additional studies with a larger number of oocytes are required to confirm the present results owing to the limited number of human oocytes in the present study.

WIDER IMPLICATIONS OF THE FINDINGS

To our knowledge, this is the first study investigating a role of the Sirt3 gene in mitochondrial biogenesis and the developmental competence of human IVM-MII oocytes. The observation may help to improve clinical application of the IVM procedure.

STUDY FUNDING/COMPETING INTERESTS

This work was supported in part by the National Natural Science Foundation of Key Program (31230047), Ministry of Science and Technology of China Grants (973 program; 2014CB943203), the National Natural Science Foundation of General Program (31371521 and 81571400), Beijing Nova Program (xxjh2015011), and Specialized Research Fund for the Doctoral Program of Higher Education (20120001130008) and the National Natural Science Foundation of Young Scholar (31501201). The authors have declared that no conflict of interest exists.

Impaired oocyte quality induced by dehydroepiandrosterone is partially rescued by metformin treatment

The present study evaluated the influence of hyperandrogenism on oocyte quality using a murine PCOS model induced by dehydroepiandrosterone (DHEA) and further explored the effect of metformin treatment. Female BALB/c mice were treated with a vehicle control or DHEA (6 mg /100 g body weight) or DHEA plus metformin (50 mg /100 g body weight) for 20 consecutive days. DHEA-induced mice resembled some characters of human PCOS, such as irregular sexual cycles and polycystic ovaries. After the model validation was completed, metaphase II (MII) oocytes were retrieved and subsequent analyses of oocyte quality were performed. DHEA-treated mice yielded fewer MII oocytes, which displayed decreased mtDNA copy number, ATP content, inner mitochondrial membrane potential, excessive oxidative stress and impaired embryo development competence compared with those in control mice. Metformin treatment partially attenuated those damages, as evidenced by the increased fertilization and blastocyst rate, ATP content, GSH concentration and GSH/GSSG ratio, and decreased reactive oxygen species levels. No significant difference in normal spindle assembly was observed among the three groups. During in vitro maturation (IVM), the periods of germinal vesicle breakdown (GVBD) and the first polar body (PB1) extrusion were extended and the maturation rate of GVBD oocytes was decreased in DHEA mice compared with controls. Metformin treatment decreased the time elapsed of GVBD while had no effect on PB1 extrusion. These results indicated that excessive androgen is detrimental to oocyte quality while metformin treatment is, directly or indirectly, beneficial for oocyte quality improvement.

Endocrine disrupting effects of dichlorodiphenyltrichloroethane analogues on gonadotropin hormones in pituitary gonadotrope cells

It has been shown that exposure to dichlorodiphenyltrichloroethane (DDT) analogues leads to disharmony of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). However, the effects and mechanisms of DDT analogues on the expression of gonadotropin genes (FSHβ, LHβ and Cgα), which is the rate-limiting step of FSH and LH biosynthesis, remain unknown. In this study, we assessed the effects of p,p'-DDT, o,p'-DDT, p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and methoxychlor (MXC) on gonadotropin genes expression and hormones synthesis in gonadotrope cells. p,p'-DDT and MXC at test concentrations ranging from 10(-9) to 10(-7)mol/L, stimulated gonadotropin genes expression and hormones synthesis in a dose-dependent manner. The activation of extracellular signal-regulated kinase (ERK) was required for the induction of gonadotropin genes expression and hormones synthesis by p,p'-DDT or MXC exposure. This study showed for the first time that p,p'-DDT and MXC regulated gonadotropin genes expression and hormones synthesis through ERK pathway in gonadotrope cells.

Aberrant epigenetic modification in murine brain tissues of offspring from preimplantation genetic diagnosis blastomere biopsies

Preimplantation genetic diagnosis (PGD) has been prevalent in the field of assisted reproductive technology, yet the long-term risks of PGD to offspring remain unknown. In the present study, the early development of PGD embryos, postimplantation characteristics, and birth rate following PGD were determined. Moreover, the behavior of the offspring conceived from the biopsied embryos was evaluated with the Morris water maze and pole climbing tests. Finally, the epigenetic modification of the global genome and methylation patterns for the H19, Igf2, and Snrpn imprinted genes were identified. The results indicated a significant delay in the blastocoel formation of PGD embryos and a decrease in the implantation ability of these embryos, which was related to the decreased number of cells in the PGD blastocysts. The PGD mice spent more time on both the nontrained quadrant of the water maze and climbing down the pole. Furthermore, the 5-hydroxymethylcytosine content in the brain tissues of PGD mice was significantly increased, but no difference was found in 5-methylcytosine content. The differentially methylated regions of H19/Igf2 exhibited decreased methylation patterns, but that of Snrpn was normal, compared to the control group. Quantitative RT-PCR indicated that Igf2 mRNA expression was significantly decreased but that H19 and Snrpn mRNAs were expressed normally. In conclusion, blastomere biopsies in PGD procedures carry potential risks to embryo development and the behavior of resulting offspring; these risks may arise from aberrant epigenetic modification and methylation patterns in brain tissues. Further studies are needed to better understand the risks associated with PGD.