In vitro activation of primordial follicles is becoming more essential in assisted reproductive technologies. Vasoactive intestinal peptide (VIP) is one of the members of the neurotrophin family which has demonstrated to have an impact on follicle development in recent years. This study aims to investigate the effect of VIP on the activation of primordial follicles in neonatal rat in an in vitro culture system and to determine the relevant molecular mechanism of their activation. Ovaries of 4-day-old rats were examined for the expression of VIP receptors and were cultured in mediums containing VIP with or without inhibitors of the ERK–mTOR signalling pathway. They were then collected for histological analysis or measurement of the molecular expression of this pathway. The receptors of VIP were found in granular cells and oocytes of primordial and early-growing follicles in neonatal ovary. The ratio of growing follicle increased in the presence VIP at different concentrations, with the highest level of increase being observed in the 10−7 mol/L VIP-treated group. The ratio of PCNA-positive granular cells was also increased, while that of the apoptotic oocytes were decreased, and protein analysis showed increased phosphorylation of ERK1/2, mTOR and RPS6 in the VIP-treated group. However, the effect of VIP on the activation of primordial follicle became insignificant with the addition of MEK inhibitor (U0126) or mTORC1 inhibitor (rapamycin). This study indicated that VIP could activate neonatal rat primordial follicle through the ERK-mTOR signalling pathway, suggesting a strategy for in vitro primordial follicle recruitment.
Song Li, Qi Fan, Yanqiu Xie, Haiyan Lin, Qi Qiu, Yihua Liang, and Qingxue Zhang
Qi Li, Na Li, Hengwei Liu, Yu Du, Haitang He, Ling Zhang, and Yi Liu
Endometriosis (EMs) is an estrogen (E2)-dependent inflammatory disorder. Although EMs is considered a benign disease, it presents with malignant characteristics, such as migration and invasion. An increasing number of studies have shown that aberrantly expressed circular RNAs (circRNAs) play an essential role in disease development and progression. However, the mechanisms by which circRNAs exert their pathological effects in EMs remain unclear. Hsa_circ_0001649, a novel cancer-associated circRNA, has been previously reported to be downregulated in several cancer types and related to cell migration and invasion. In the present study, real-time PCR (qRT-PCR) was carried out to measure hsa_circ_0001649 levels in human tissues, human primary endometrial stromal cells (ESCs) and a human endometrial stromal cell line (ThESCs). Matrix metalloproteinase 9 (MMP9) levels in ESCs and ThESCs were assessed by qRT-PCR and Western blotting, and the migration and invasion capacities of ThESCs were evaluated by transwell assay. As a result, hsa_circ_0001649 expression was significantly decreased in ectopic and eutopic endometrial samples compared with that in normal endometrial samples. E2 decreased hsa_circ_0001649 expression but increased MMP9 expression in ESCs and ThESCs. Furthermore, ThESCs were more invasive under E2 stimulation. However, these effects disappeared when ICI or hsa_circ_0001649 transfection was used. Collectively, our findings reveal that decreased hsa_circ_0001649 expression plays a role in E2-increased MMP9 expression through E2 receptors (ERs), which have critical functions in EMs.
Hai-Yan Hou, Xi Wang, Qi Yu, Hong-Yi Li, Shao-Jie Li, Rui-Yi Tang, Zai-Xin Guo, Ya-Qiong Chen, Chun-Xiu Hu, Zhi-Juan Yang, Wen-ke Zhang, and Yan Qin
Decline in successful conception decreases more rapidly after 38 years of age owing to follicular depletion and decreased oocyte quality. However, limited information is available regarding the underlying mechanism and the useful treatment. This study aimed to evaluate the effects of growth hormone supplementation on oocyte maturation in vivo in aged and young mice and to determine its effect on mitochondrial function. The influence of three different doses of recombinant human growth hormone (rhGH) (0.4, 0.8 and 1.6 mg/kg/day) for 8 weeks before ovarian stimulation was analyzed. Superovulated oocytes were released from the oviduct of 12-week-old and 40-week-old female C57BL/6J mice 14–16 h after administration of human chorionic gonadotropin. Ovarian follicle and morphological analysis and oocyte maturation parameters were then evaluated. This study is the first, to our knowledge, to report that medium- and high-dose rhGH significantly increases antral follicles in aged mice but anti-Müllerian hormone (AMH) levels. Furthermore, derived oocytes, MII-stage oocyte rate, ATP levels, mitochondrial membrane potential and frequencies of homogeneous mitochondrial distribution increased. In contrast, in both aged and young mice, the mtDNA copy numbers per oocyte were similar before rhGH administration, and upon saline administration, they did not differ significantly. We conclude that medium-dose rhGH supplementation before standard ovarian stimulation regimens improves oocyte quality in aged mice, probably by enhancing mitochondrial functionality.