Thymoquinone reduces intracytoplasmic oxidative stress and improves epigenetic modification in polycystic ovary syndrome mice oocytes, during in‐vitro maturation

Abstract

Although in‐vitro maturation (IVM) of oocytes has been presented as an alternative treatment to traditional stimulated in‐vitro fertilization, the culture condition can be improved by natural antioxidants. Thus, we investigated the protective effect of Thymoquinone (TQ) during IVM in the polycystic ovary syndrome (PCOS) mice model. The induction of PCOS was made by dehydroepiandrosterone via subcutaneous injection, in prepubertal female B6D2F1‐mice. After 21 days later, germinal vesicle (GV)‐stage‐oocytes were extracted and incubated in IVM media containing 0, 1.0, 10.0, and 100.0 μM of TQ. To assess fertilization and blastulation rates, after 22–24 hr, the treated oocytes were fertilized in‐vitro with epididymal spermatozoa. Some other oocytes were evaluated for maturation, epigenetic, and oxidative stress markers. Similarly, the mRNA expression of epigenetic enzymes genes (Dnmt1 and Hdac1), three maternally derived genes (Mapk, CyclinB, and Cdk1) and apoptosis‐related genes (Bax and Bcl2) were assessed. Our results showed that the maturation, fertilization, and blastulation rates were significantly higher in the 10.0 μM TQ‐treated group compared with the untreated group and likewise with in‐vivo matured oocytes. The Bax expression was reduced in 10.0 μM TQ matured oocytes, but Bcl2, Dnmt1, Hdac1, Cdk1, and Mapk were upregulated in this group compared to other groups. Furthermore, dimethylation of histone‐3 at lysine‐9 (H3K9m2) and DNA methylation were significantly increased whereas H4K12 acetylation (H4K12ac) was decreased in the 10.0 μM TQ‐treated group in comparison with control and in‐vivo matured oocytes. Therefore, our results are suggesting that 10.0 μM TQ may enhance the developmental competence of PCOS oocytes via the modulation of oxidative stress and epigenetic alterations.

Coping with DNA Double-Strand Breaks via ATM Signaling Pathway in Bovine Oocytes

“…H1foo, a unique sub-type, can only be found in oocytes of different organisms [16,17]. Cyclin B, a maternally derived gene, is involved in cell cycle regulation and plays an important role during oocyte maturation [18,19]. Our results showed that GDF-9 and BMP-15 were downregulated in immature oocytes under the action of KU-55933, compared with the control, while their trend was contrary to that of H1foo.…”

“…Besides oocyte shape, the cytoplasm and its contents, perivitelline space, zona pellucida, the morphology of the PBI (the first polar body), spindle morphology, follicular fluid, and cumulus cells are the main terms considered [1][2][3][4][5][6][7][8]. In addition, some molecular-level detection indicators may also reflect the quality of oocytes, such as GDF9 (growth and differentiation factor 9), BMP15 (bone morphogenetic protein 15) [9][10][11][12][13], FSHR (follicle-stimulating hormone receptor) [14,15], H1foo (oocyte-specific histone 1) [16,17], cyclin B [18,19], and so on.…”

2,3,5,4′-Tetrahydroxystilbene-2-O-β-D-Glucoside improves female ovarian aging

“…Cumulus oocyte complexes (COCs) were physically retrieved from antral follicles in a HEPES-buffered tissue culture medium using a pair of 27-G needles under a stereomicroscope (Nikon, SMZ645, Tokyo, Japan) ( Liu and Keefe, 2002 ). After washing 3-times with tissue culture medium, oocytes were then collected from young mice groups (8- to 36-week-old mice) and aged mice groups (28- to 40-week-old mice), only the MII oocytes that have extruded were collected in DMEM/F12 medium containing 10% fetal bovine serum ( Eini et al, 2019 ).…”

Posttranslational modifications in pathogenesis of PCOS

“…Existing studies proposed that PCOS is related to histone acetylation. In DHEA-induced PCOS mice, excessive reactive oxygen species (ROS) production increased acetylation of histone H4K12 leading to excessive abnormal oocyte morphology and reduced polar body extrusion rate (54). Deacetylation of histones by HDAC enzymes is one of the characteristics of chromosome condensation, which is associated with transcriptional repression during oocyte maturation.…”