Growth hormone treatment improves the development of follicles and oocytes in prepubertal lambs

Lactational high weight loss impairs follicular development by causing mitochondrial dysfunction of ovarian cells in sows and mitigated by butyrate supplement

INTRODUCTION

In modern sows, lactational high weight loss (HWL), caused by the large litter size and inadequate feed intake, has a negative effect on follicular development after weaning, resulting in poor reproductive performance in the subsequent parity. However, the underlying mechanism remains unclear.

OBJECTIVES

This research aimed to explore the mechanism that sows HWL during lactation damages follicular development and attempt to improve the reproductive function by treating with butyrate.

METHOD

Four multiparous sister sows were chosen to build a HWL model for lactating sows through feed restriction during the final week of a 21-day lactation. Spatially transcriptomics (ST) and tissue immunofluorescent staining were then utilized for the antral follicles in the ovarian surface to search for differentially expressed genes and proteins among different cell types. Subsequently, the mouse assay, including immunofluorescent staining, transmission electron microscopy, hormone detection and western blot, were conducted to verify the findings in sows and investigate the effect of butyrate on the follicular development in HWL mice.

RESULTS

Based on the transcriptomic analysis, differentially expressed genes in granulosa cells, theca cells, and ovarian stromal cells were examined. The findings revealed that HWL disturbs the mitochondrial electron transport chain and steroidogenesis in all three cell types by downregulating the expression of NDUFB3, SDHB, CYCS, COX8A and CYP19A1, as well as upregulating the expression of STAR, CYP11A1 and CYP17A1. Furthermore, results from mouse assays demonstrated that HWL causes apoptosis and alters sex hormone secretion by impairing mitochondrial function and disordering the expression of steroidogenesis key enzymes in ovarian cells, while these effects were partially mitigated by butyrate treatment.

CONCLUSION

The mitochondrial dysfunction and abnormal steroidogenesis induced by HWL during lactation in ovarian cells harm the follicular development of weaning sows, which could be alleviated by butyrate treatment.

The relationship between psychological stress and ovulatory disorders and its molecular mechanisms: a narrative review

This narrative review explores the relationship between psychological stress and ovulatory disorders, focusing on the molecular mechanisms involved. Ovulation is regulated by the hypothalamus-pituitary-ovarian (HPO) axis, and disruptions in this axis can lead to ovulatory dysfunction. Chronic psychological stress affects the HPO axis, resulting in abnormalities in hypothalamus hormone secretion, pituitary hormone release, and ovarian function. These disruptions cause ovulation disorders and menstrual irregularities. The mechanisms by which psychological stress affects ovulation involve alterations in neuropeptides and hormones, activation of the hypothalamic-pituitary-adrenal (HPA) axis, impairment of follicular development, generation of oxidative stress, and the decline in ovarian reserve function. Understanding these mechanisms is crucial for developing interventions to restore reproductive health. Psychological interventions, such as cognitive-behavioral therapy, have shown promise in improving ovulation and pregnancy rates in women with ovulatory disorders. Further research is needed to explore the specific mechanisms of these interventions and optimize treatment strategies. Addressing psychological factors is essential in managing reproductive health and ovulatory disorders.

Effect of different growth hormone pretreatment times in assisted reproductive therapy for patients with diminished ovarian reserve: A retrospective pilot cohort study

This study aimed to evaluate the effect of different growth hormone (GH) pretreatment times in assisted reproductive therapy in patients with diminished ovarian reserve (DOR). A retrospective pilot cohort analysis was performed on patients with DOR receiving GH pretreatment in the Assisted Reproduction Unit of Sir Run Run Shaw Hospital. A total of 1459 patients met the criteria and were divided into four groups according to GH pretreatment time as follows: 53 were in the 2-month pretreatment group (GH1), 400 were in the 1-month pretreatment group (GH2), 414 were in the ovulation induction period pretreatment group (GH3), and 592 were in the non-GH pretreatment group (control group). In addition, GH1, GH2, and GH3 were combined in the GH pretreatment group. Baseline characteristics and treatment outcomes were compared between the groups. The number of oocytes retrieved in the GH pretreatment, GH1, GH2, and GH3 groups was significantly higher than that in the control group (all P < .01). The numbers of oocytes retrieved in the GH1 and GH2 groups were similar but were nominally higher than those in the GH3 group. Estradiol concentrations in the GH pretreatment, GH2, and GH3 groups were significantly higher than those in the control group on the day of human chorionic gonadotropin injection (all P < .01). In the GH1 group, 22 patients had >1 assisted reproductive therapy cycle (non-GH pretreatment) before GH pretreatment, and the number of oocytes retrieved in the GH pretreatment cycle was higher than that in the non-GH pretreatment cycle, but this was not significant. These findings suggest that the GH pretreatment time was appropriately prolonged, and the number of oocytes retrieved nominally increased. In patients with DOR, GH pretreatment improved treatment outcomes. More than 1 month of GH pretreatment did not increase the number of oocytes retrieved.

Use of assisted reproductive technologies (ARTs) to shorten the generational interval in ruminants: current status and perspectives

The challenges posed by climate change and increasing world population are stimulating renewed efforts for improving the sustainability of animal production. To meet such challenges, the contribution of genomic selection approaches, in combination with assisted reproductive technologies (ARTs), to spreading and preserving animal genetics is essential. The largest increase in genetic gain can be achieved by shortening the generation interval. This review provides an overview of the current status and progress of advanced ARTs that could be applied to reduce the generation time in both female and male of domestic ruminants. In females, the use of juvenile in vitro embryo transfer (JIVET) enables to generate offspring after the transfer of in vitro produced embryos derived from oocytes of prepubertal genetically superior donors reducing the generational interval and acceleration genetic gain. The current challenge is increasing in vitro embryo production (IVEP) from prepubertal derived oocytes which is still low and variable. The two main factors limiting IVEP success are the intrinsic quality of prepubertal oocytes and the culture systems for in vitro maturation (IVM). In males, advancements in ARTs are providing new strategies to in vitro propagate spermatogonia and differentiate them into mature sperm or even to recapitulate the whole process of spermatogenesis from embryonic stem cells. Moreover, the successful use of immature cells, such as round spermatids, for intracytoplasmic injection (ROSI) and IVEP could allow to complete the entire process in few months. However, these approaches have been successfully applied to human and mouse whereas only a few studies have been published in ruminants and results are still controversial. This is also dependent on the efficiency of ROSI that is limited by the current isolation and selection protocols of round spermatids. In conclusion, the current efforts for improving these reproductive methodologies could lead toward a significant reduction of the generational interval in livestock animals that could have a considerable impact on agriculture sustainability.

Analysis of Transcriptomic Differences in the Ovaries of High- and Low-Laying Ducks

The egg-laying performance of Shan Ma ducks (Anas Platyrhynchos) is a crucial economic trait. Nevertheless, limited research has been conducted on the egg-laying performance of this species. We examined routine blood indicators and observed higher levels of metabolic and immune-related factors in the high-egg-production group compared with the low-egg-production group. Furthermore, we explored the ovarian transcriptome of both high- and low-egg-production groups of Shan Ma ducks using Illumina NovaSeq 6000 sequencing. A total of 1357 differentially expressed genes (DEGs) were identified, with 686 down-regulated and 671 up-regulated in the high-egg-production (HEP) ducks and low-egg-production (LEP) ducks. Several genes involved in the regulation of ovarian development, including neuropeptide Y (NPY), cell cycle protein-dependent kinase 1 (CDK1), and transcription factor 1 (E2F1), exhibited significant differential expressions at varying stages of egg production. Pathway functional analysis revealed that the DEGs were primarily associated with the steroid biosynthesis pathway, and the neuroactive ligand-receptor interaction pathway exhibited higher activity in the HEP group compared to the LEP group. This study offers valuable information about and novel insights into high egg production.

Mito-TEMPO Improves the Meiosis Resumption and Mitochondrial Function of Vitrified Sheep Oocytes via the Recovery of Respiratory Chain Activity

Vitrification is a crucial method for preserving animal germ cells. Considering the increased oxidative stress and organelle damage incurred, it is still necessary to make the process more efficient for oocytes. As the energy source of oocytes, mitochondria are the most abundant organelle in oocytes and play a crucial role in their maturation. Here, we found that Mito-TEMPO, a mitochondria-targeted antioxidant, could efficaciously improve the oxidative stress injury of vitrified oocytes by recovering mitochondrial function via the mitochondrial respiratory chain. It was observed that Mito-TEMPO not only improves oocyte viability and meiosis but also maintains spindle structure. A subsequent study indicated that Mito-TEMPO effectively rescued mitochondrial dysfunction and attenuated vitrification-induced oxidative stress. Further investigation revealed that Mito-TEMPO regulates vitrified oocytes' intracellular Ca2+ homeostasis and ATP content and provides strong antioxidant properties. Additionally, an analysis of the transcriptome at the single-cell level revealed that the respiratory chain mediates the beneficial effect of Mito-TEMPO on vitrified oocytes. Overall, our findings indicate that supplementing oocytes with Mito-TEMPO is an effective method to shield them from the damage caused by vitrification. In addition, the beneficial effects of Mito-TEMPO on vitrified sheep oocytes could inspire further investigations of the principles underlying oocyte cryobiology in other animals.