Sonic Hedgehog promotes in vitro oocyte maturation and term development of embryos in Taiwan native goats

Anethole supplementation during in vitro maturation increases in vitro goat embryo production in a concentration-dependent manner

During in vitro maturation (IVM) cumulus-oocyte complexes (COCs) are exposed to conditions that can trigger oxidative stress, thus, reducing oocyte maturation and viability. Aiming to mitigate these detrimental conditions, the effects of IVM medium supplementation with anethole have been tested. Anethole, also known as trans-anethole (1-methoxy-4 [1-propenyl]-benzene), is a naturally occurring phenylpropanoid with various pharmacological properties, including antioxidant effects. However, no study has examined anethole effect on goat COCs during IVM. Thus, the aim of this study was to evaluate the effects of different anethole concentrations on oocyte maturation, oxidative stress, and in vitro development of caprine embryos after parthenogenetic activation. Goat COCs were selected and randomly distributed into the following treatments: TCM-199+ medium (control), or TCM-199+ medium supplemented with 30 μg/mL (AN30); 300 μg/mL (AN300) or 2000 μg/mL (AN2000) of anethole. After IVM, part of the COCs was chosen for oocyte viability and chromatin configuration, intracellular reactive oxygen species levels, and mitochondrial membrane potential assessment. Another part of COCs was parthenogenetically activated, and presumptive zygotes were cultured for 7 days. Results demonstrated that anethole at 30 μg/mL increased oocyte maturation and cleavage rates when compared to the other treatments (P < 0.05), as well as oocyte viability and in vitro embryo production when compared to the control treatment (P < 0.05). Additionally, treatment with anethole at 2000 μg/mL decreased oocyte nuclear maturation and cleavage rates when compared to other treatments (P < 0.05) and embryo production if compared to control and AN30 treatments (P < 0.05). Moreover, anethole at 2000 μg/mL increased mitochondrial membrane potential when compared to the other treatments (P < 0.05). In conclusion, anethole exerts a concentration-dependent effect during goat COCs IVM. For a more desirable outcome of oocyte viability and maturation, and in vitro embryo production, the use of anethole at 30 μg/mL is recommended.

In vitro embryo production in small ruminants: what is still missing?

In vitro embryo production (IVEP) is an extremely important tool for genetic improvement in livestock and it is the biotechnology that has grown the most recently. However, multiple ovulation followed by embryo transfer is still considered the leading biotechnology for embryo production in small ruminants. This review aimed to identify what is still missing for more efficient diffusion of IVEP in small ruminants, going through the IVEP steps and highlighting the main factors affecting the outcomes. Oocyte quality is essential for the success of IVEP and an aspect to be considered in small ruminants is their reproductive seasonality and strategies to mitigate the effect of season. The logistics for oocyte collection from live females is more complex than in cattle, and tools to simplify this collection system and/or to promote an alternative way of recovering oocytes may be an important point in this scenario. The heterogeneity of oocytes collected from growing follicles in live females or from ovaries collected from abattoirs remains a challenge, and there is a demand to standardize/homogenize the hormonal stimulatory protocols and IVM protocols for each source of oocytes. The use of sexed semen is technically possible, however the low market demand associated with the high costs of the sexing process prevents the routine use of this technique, but its higher availability is an important aspect aiming for greater dissemination of IVEP. New noninvasive approaches for embryo selection are key factors since the selection for transfer or cryopreservation is another difficulty faced among laboratories. Embryo selection is based on morphological traits, although these are not necessarily reliable in predicting pregnancy. Several issues described in this review must be considered by researchers in other to promote the diffusion of IVEP in small ruminants.

Restoration of Developmental Competence in Low-Quality Porcine Cumulus–Oocyte Complexes through the Supplementation of Sonic Hedgehog Protein during In Vitro Maturation

The sonic hedgehog (SHH) pathway is an important signaling pathway for mammalian ovarian folliculogenesis and oocyte maturation. A previous study demonstrated that low-quality porcine cumulus–oocyte complexes (COCs) have low developmental competence, with lower SHH signaling protein expression before and after in vitro maturation (IVM) than high-quality COCs. However, there is no reported evidence on the restorative effects of SHH protein supplementation during the IVM of low-quality porcine COCs. Therefore, this study investigated the effects of SHH protein supplementation on the IVM of low-quality porcine COCs, as assessed by brilliant cresyl blue (BCB) staining. To examine this, we designed four groups: (i) BCB− (low-quality), (ii) BCB− + SHH, (iii) BCB+ (high-quality), and (iv) BCB+ + SHH. While the supplementation of SHH protein with high-quality COCs had no effect, supplementation with low-quality COCs significantly improved cumulus cell expansion, metaphase II rate, and subsequent embryo development following parthenogenetic activation. Our results provide the first evidence that the low developmental competence of low-quality porcine COCs can be improved by supplementation with the SHH protein. These results indicate that an active SHH signaling pathway is required for the acquisition of developmental competence in porcine COCs.

Anethole improves the developmental competence of porcine embryos by reducing oxidative stress via the sonic hedgehog signaling pathway

BACKGROUND

Anethole (AN) is an organic antioxidant compound with a benzene ring and is expected to have a positive impact on early embryogenesis in mammals. However, no study has examined the effect of AN on porcine embryonic development. Therefore, we investigated the effect of AN on the development of porcine embryos and the underlying mechanism.

RESULTS

We cultured porcine in vitro-fertilized embryos in medium with AN (0, 0.3, 0.5, and 1 mg/mL) for 6 d. AN at 0.5 mg/mL significantly increased the blastocyst formation rate, trophectoderm cell number, and cellular survival rate compared to the control. AN-supplemented embryos exhibited significantly lower reactive oxygen species levels and higher glutathione levels than the control. Moreover, AN significantly improved the quantity of mitochondria and mitochondrial membrane potential, and increased the lipid droplet, fatty acid, and ATP levels. Interestingly, the levels of proteins and genes related to the sonic hedgehog (SHH) signaling pathway were significantly increased by AN.

CONCLUSIONS

These results revealed that AN improved the developmental competence of porcine preimplantation embryos by activating SHH signaling against oxidative stress and could be used for large-scale production of high-quality porcine embryos.

GIMAP7 induces oxidative stress and apoptosis of ovarian granulosa cells in polycystic ovary syndrome by inhibiting sonic hedgehog signalling pathway

Polycystic ovary syndrome (PCOS) is a gynaecological endocrine disease. The objective of the present study was to investigate the role of GTPase immunity-associated protein (GIMAP) 7 in PCOS. A PCOS rat model was established using dehydroepiandrosterone injection. The data showed that GIMAP7 was mainly located in granulosa cells and was abundantly expressed in the ovarian granulosa cells of PCOS rats. GIMAP7 silencing decreased blood glucose levels, HOMA-IR scores, and number of cystic follicles. In addition, GIMAP7 silencing corrected erratic oestrous cycles, inhibited apoptosis and reduced c-caspase-3 protein expression in the ovarian tissues of PCOS rats. GIMAP7 silencing reduced malondialdehyde (MDA) but increased glutathione (GSH) and superoxide dismutase (SOD) levels in the serum and ovarian tissues of PCOS rats. The effects of GIMAP7 were further investigated in human ovarian granulosa KGN cells. GIMAP7 silencing increased the viability, promoted proliferation, and increased the percentage of S-phase KGN cells. The apoptosis rate was significantly decreased by GIMAP7 silencing. GIMAP7 also inhibited oxidative stress in KGN cells, resulting in decreased levels of reactive oxygen species (ROS) and MDA and increased levels of GSH and SOD. Notably, GIMAP7 inhibited the sonic hedgehog (SHH) signalling pathway, and GIMAP7 silencing increased the expression of the SHH signalling pathway downstream genes SHH, SMO, and Gli1. Inhibition of the SHH signalling pathway using cyclopamine reduced the effect of GIMAP7 silencing on KGN cells. This study proved that GIMAP7 promotes oxidative stress and apoptosis in ovarian granulosa cells in PCOS by inhibiting the SHH signalling pathway.

In vitro production of small ruminant embryos: latest improvements and further research

This review presents the latest advances in and main obstacles to the application of invitro embryo production (IVEP) systems in small ruminants. This biotechnology is an extremely important tool for genetic improvement for livestock and is essential for the establishment of other biotechnologies, such as cloning and transgenesis. At present, the IVEP market is almost non-existent for small ruminants, in contrast with the trends observed in cattle. This is probably related to the lower added value of small ruminants, lower commercial demand and fewer qualified professionals interested in this area. Moreover, there are fewer research groups working on small ruminant IVEP than those working with cattle and pigs. The heterogeneity of oocytes collected from growing follicles in live females or from ovaries collected from abattoirs remains a challenge for IVEP dissemination in goats and sheep. Of note, although the logistics of oocyte collection from live small ruminant females are more complex than in the bovine, in general the IVEP outcomes, in terms of blastocyst production, are similar. We anticipate that after appropriate training and repeatable results, the commercial demand for small ruminant invitro -produced embryos may increase.

Baicalin improves the in vitro developmental capacity of pig embryos by inhibiting apoptosis, regulating mitochondrial activity and activating sonic hedgehog signaling

Baicalin, a traditional Chinese medicinal monomer whose chemical structure is known, can be used to treat female infertility. However, the effect of baicalin on embryonic development is unknown. This study investigated the effects of baicalin on in vitro development of parthenogenetically activated (PA) and in vitro fertilized (IVF) pig embryos and the underlying mechanisms involved. Treatment with 0.1 μg/ml baicalin significantly improved (P < 0.05) the in vitro developmental capacity of PA pig embryos by reducing the reactive oxygen species (ROS) levels and apoptosis and increasing the mitochondrial membrane potential (ΔΨm) and ATP level. mRNA and protein expression of sonic hedgehog (SHH) and GLI1, which are related to the SHH signaling pathway, in PA pig embryos at the 2-cell stage, were significantly higher in the baicalin-treated group than in the control group. To confirm that the SHH signaling pathway is involved in the mechanism by which baicalin improves embryonic development, we treated embryos with baicalin in the absence or presence of cyclopamine (Cy), an inhibitor of this pathway. Cy abolished the effects of baicalin on in vitro embryonic development. In conclusion, baicalin improves the in vitro developmental capacity of PA and IVF pig embryos by inhibiting ROS production and apoptosis, regulating mitochondrial activity and activating SHH signaling.

Effect of Oocyte Quality Assessed by Brilliant Cresyl Blue (BCB) Staining on Cumulus Cell Expansion and Sonic Hedgehog Signaling in Porcine during In Vitro Maturation

Brilliant cresyl blue (BCB) staining is used to select developmentally competent cumulus-oocyte complexes (COCs) for in vitro maturation (IVM). However, limited attention has been paid to what drives the higher developmental competence of BCB+ COCs. Sonic hedgehog signaling (SHH) is an important signaling pathway for ovarian follicular development and oocyte maturation. Therefore, this study investigated the effect of oocyte quality assessed by BCB staining on cumulus cell expansion, oocyte nuclear maturation, subsequent embryo development, apoptosis levels, and SHH signaling protein expression, in porcine COCs. After IVM, BCB+ COCs exhibited a significantly higher proportion of complete cumulus cell expansion and metaphase II rate in oocytes than BCB- COCs. After in vitro fertilization, the BCB+ group showed a significantly higher monospermy rate, fertilization efficiency, percentage of cleavage and blastocyst formation, with a higher total cell number and a lower apoptosis in blastocysts as compared with the BCB- group. Furthermore, significantly lower apoptosis levels and a higher expression of SHH-signaling proteins in COCs were observed, before and after IVM. In conclusion, high-quality oocytes had a greater potential to expand their surrounding cumulus cells with active SHH signaling and a lower apoptosis. This could provide COCs with a proper environment for maturation, thereby leading to a better subsequent embryo development.

Hedgehog pathway inhibition causes primary follicle atresia and decreases female germline stem cell proliferation capacity or stemness

Background

Follicle depletion is one of the causes of premature ovarian failure (POF) and primary ovarian insufficiency (POI). Hence, maintenance of a certain number of female germline stem cells (FGSCs) is optimal to produce oocytes and replenish the primordial follicle pool. The mechanism that regulates proliferation or stemness of FGSCs could contribute to restoring ovarian function, but it remains uncharacterized in postnatal mammalian ovaries. This study aims to investigate the mechanism by which inhibiting the activity of the hedgehog (Hh) signaling pathway regulates follicle development and FGSC proliferation.

Methods and results

To understand the role of the Hh pathway in ovarian aging, we measured Hh signaling activity at different reproductive ages and the correlation between them in physiological and pathological mice. Furthermore, we evaluated the follicle number and development and the changes in FGSC proliferation or stemness after blocking the Hh pathway in vitro and in vivo. In addition, we aimed to explain one of the mechanisms for the FGSC phenotype changes induced by treatment with the Hh pathway-specific inhibitor GANT61 via oxidative stress and apoptosis. The results show that the activity of Hh signaling is decreased in the ovaries in physiological aging and POF models, which is consistent with the trend of expression levels of the germline stem cell markers Mvh and Oct4. In vitro, blocking the Hh pathway causes follicular developmental disorders and depletes ovarian germ cells and FGSCs after treating ovaries with GANT61. The proliferation or stemness of cultured primary FGSCs is reduced when Hh activity is blocked. Our results show that the antioxidative enzyme level and the ratio of Bcl-2/Bax decrease, the expression level of caspase 3 increases, the mitochondrial membrane potential is abnormal, and ROS accumulate in this system.

Conclusions

We observed that the inhibition of the Hh signaling pathway with GANT61 could reduce primordial follicle number and decrease FGSC reproductive capacity or stemness through oxidative damage and apoptosis.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1299-5) contains supplementary material, which is available to authorized users.