ABSTRACT
Advanced glycation end products (AGEs) are the final products of the Maillard reaction, formed through the interaction of carbohydrates and proteins. Reactive dicarbonyl compounds such as methylglyoxal (MGO) serve as precursors for AGEs formation. Elevated levels of MGO/AGEs are observed in conditions like obesity, polycystic ovarian syndrome (PCOS), and diabetes, negatively impacting oocyte development. Previous studies have shown that hydrogen sulfide, a gasotransmitter with anti-AGEs effects, is produced in a process influenced by vitamin B6. R-α-lipoic acid (ALA) inhibits protein glycation and AGEs formation while stimulating glutathione (GSH) production. Taurine mitigates oxidative stress and acts as an anti-glycation compound, preventing in vitro glycation and AGEs accumulation. This study aimed to explore the ameliorative effects of a micronutrient support (Taurine, ALA and B6: TAB) on mouse oocytes challenged with MGO. Our results indicate that MGO reduces oocyte developmental competence, while TAB supplementation improves maturation, fertilization, and blastocyst formation rates. TAB also restores cell lineage allocation, redox balance and mitigates mitochondrial dysfunction in MGO-challenged oocytes. Furthermore, cumulus cells express key enzymes in the transsulfuration pathway, and TAB enhances their mRNA expression. However, TAB does not rescue MGO-induced damage in denuded oocytes, emphasizing the supportive role of cumulus cells. Overall, these findings suggest that TAB interventions may have significant implications for addressing reproductive dysfunctions associated with elevated MGO/AGEs levels. This study highlights the potential of TAB supplementation in preserving the developmental competence of COCs exposed to MGO stress, providing insights into mitigating the impact of dicarbonyl stress on oocyte quality and reproductive outcomes.
Subject(s)
Oocytes , Pyruvaldehyde , Taurine , Thioctic Acid , Vitamin B 6 , Animals , Taurine/pharmacology , Pyruvaldehyde/pharmacology , Pyruvaldehyde/metabolism , Oocytes/drug effects , Oocytes/metabolism , Mice , Thioctic Acid/pharmacology , Female , Vitamin B 6/pharmacology , Vitamin B 6/metabolism , Glycation End Products, Advanced/metabolism , Oxidative Stress/drug effects , Mitochondria/metabolism , Mitochondria/drug effectsABSTRACT
Apoptosis is a programed cell death that is vital for tissue homeostasis. However, embryo apoptosis had been known to be related to embryo fragmentation which should be avoided in in vitro fertilization (IVF). The purpose of this study was to evaluate the relationship of embryo apoptosis with the grade of immature oocytes and cleavage stage of in vitro produced (IVP) cattle embryos. This study consisted of 345 oocytes collected through ovary slicing. Immature oocytes were graded as A, B and C. This grading was based on cumulus cell thickness and compactness. All oocytes then underwent an in vitro maturation (IVM) procedure. An IVF was done 24 h after IVM culture. Prior to staining, stage of cleaved embryos was determined and classified as either 2, 4, 8 or >8-cell embryo stage. Apoptosis status of cleaved IVP embryos was determined by using annexin V-FITC staining technique at 48 and 72 h post insemination (hpi). Apoptosis status for each embryo was classified as either early or late. The result showed that there was no significant difference (p > 0.05) of apoptosis status among grade A, B and C embryos. All grades of oocytes showed embryo apoptosis where 1.5% late apoptosis for grade A, 4.5% and 10.4% of early and late apoptosis for grade B and grade C. Early apoptosis was not seen in grade A embryo. We also noted no significant difference (p > 0.05) of apoptosis status between 2, 4, 8 and >8-cell embryo stage. Early apoptosis was also not seen in >8-cell stage. Even though there were no differences in apoptosis expression between the three classes, the cleavage rate of grade A oocytes was significantly higher (p < 0.01) than grade B and grade C. In conclusion, the apoptosis expression in the embryo can occur regardless of the oocyte quality and the cleavage stage of the embryo produced.
ABSTRACT
Purpose: Improving in vitro maturation could increase the rate of pregnancy from oocytes matured in vitro. Consequently, patients will be prevented from using gonadotropin with its related side effects. In this study, the maturation medium was enriched by platelet lysate (PL), then maturation and subsequent developments were monitored. Methods: Oocytes at germinal vesicle stage with cumulus cells (cumulus-oocyte complex) and without cumulus cells (denuded oocytes) were obtained from mature female mice. The maturation medium was enriched by 5 and 10 % PL and 5 % PL + 5 % fetal bovine serum (FBS) as experimental groups; the control groups' media consisted of 5 and 10 % FBS. After 18 h, the matured oocytes were collected and, after fertilization, subsequent development was monitored. Results: The rates of maturation, fertilization and 2-cell embryo development for the denuded oocyte groups in experimental media 5 % PL and 5 % PL + 5 % FBS were significantly higher than those of the control groups (P < 0.05), while the results for the cumulus-oocyte complex groups were similar between the experimental groups and control groups. Conclusions: The results of this study indicated that platelet lysate could improve the maturation rate in the absence of granulosa cells compared to media with FBS. This extract also had positive effects on fertilization and embryo development.
ABSTRACT
The aim of the present study was to clarify interactions between oocytes and cumulus cells (CCs) on the level of cumulus expansion and oocyte maturation during IVM of cumulus-oocyte complexes (COCs) in a chemically defined medium using a system that allows individual tracking of oocytes. Especially, the influence of oocyte-secreted factors was investigated by the aid of addition of denuded oocytes (DOs) as a possible approach to improve the IVM system. The basic maturation medium was porcine oocyte medium with addition of gonadotropins only during the first 20 hours of IVM. During IVM, COCs were kept fixed to the bottom of culture dish by adhesive Cell-Tak coating, which enabled individual tracking of COCs during IVM. Size changes in COCs during IVM were measured by digital image analysis. Cumulus expansion in a porcine oocyte medium of intact COCs increased in a typical manner until 20 hours and decreased in size subsequently until 48 hours of IVM (P < 0.05). Removal of oocytes from COCs by oocytectomy allowed the expansion of CCs to some extent, although their expansion ability was lower than that of COCs (P < 0.05). Addition of DOs (COCs to DOs ratio of 9:16) did not improve cumulus expansion and oocyte maturation rates of intact COCs (P > 0.05) but did enhance cumulus expansion of oocytectomized complexes (P < 0.05). Furthermore, removal of CCs before IVM increased oocyte maturation rates compared with COCs (52.3% and 32.9%, respectively) (P < 0.05) and a similar effect was observed in COCs when the gap junction inhibitor carbenoxolone was added to the IVM medium: carbenoxolone repressed the expansion of COCs at 20 hours of IVM. In conclusion, the porcine oocyte enhances cumulus expansion both by gap junctional communications and presumably by oocyte-secreted factor production. Nevertheless, the presence of oocytes is not a prerequisite for this process. In return, CCs maintain meiotic arrest in cumulus-enclosed oocytes during the initial culture through gap junctions. On the basis of these findings, future research could investigate if coculture with DOs during IVM is beneficial for fertilization and embryo development.
Subject(s)
Culture Media/chemistry , Cumulus Cells/physiology , In Vitro Oocyte Maturation Techniques/veterinary , Oocytes/physiology , Swine/physiology , Animals , Cell Culture Techniques/methods , Cell Culture Techniques/veterinary , Coculture Techniques/methods , Coculture Techniques/veterinary , Culture Media/pharmacology , Cumulus Cells/cytology , Oocytes/cytologyABSTRACT
Objective Potential roles of the C-ERBB_(2) protooncogene in mouse oocyte maturation and in conducting Epidermal Growth Factor(EGF) promoteing mouse oocyte maturation in vitro were investigated.Methods This research used mouse oocyte culture model and RT-PCR method to study the effects of both(C-ERBB_(2) and EGF(on mouse) oocyte maturation in vitro,and the potential role of the C-ERBB_(2)protooncogene on EGF effect.Results(C-ERBB_(2) ASODN inhibited germinal vesical breakdown(GVBD) and the first polar(PBⅠ) extrusion of denuded(oocytes(DOs) in a dose-dependent and time-dependent way,and delayed their maturation significantly.C-ERBB_(2) ASODN also inhibited the effect of EGF on oocyte maturation in a time-dependent way.In GVBD oocytes,RT-PCR showed that C-ERBB_(2) mRNA was expressed in oocytes and the level of (C-ERBB_(2) mRNA) was the highest in(EGF treated) group,midst in EGF+c-erbB_2ASODN treated group,and lowest in C-ERBB_(2) ASODN treated group.Conclusion C-ERBB_(2) exists in the oocyte and has promoting effect on oocyte maturation in vitro.EGF plays a rolein inducing denuded oocyte maturation through up-regulating C-ERBB_(2)expression of oocyte.Interfering C-ERBB_(2) expression can reduce the effect of EGF on oocyte maturation.