Background/Objectives: Cellular oxidative stress is crucial for GV stage oocyte vitrification quality. PI3K and the aquaporin family have been shown to facilitate various cellular processes related to redox homeostasis and energy balance; yet, the mechanisms underlying the involvement of aquaporin 7 (AQP7) in vitrified oocyte oxidative stress remain unclear. The purpose of the present investigation was to evaluate the role of AQP7 in vitrified oocytes and the mechanisms involved. Methods: AQP7 inhibitors were employed to investigate the effect of AQP7 on oxidative stress in mouse-vitrified oocytes, whereas PI3K activators were harnessed to ascertain whether AQP7 serves as a functional molecule involved in this process. Results: Our results indicate that AQP7 inhibition in vitrified oocytes results in a significant decrease in glutathione (GSH) levels associated with cellular oxidation and an elevation in H₂O₂ levels. This was accompanied by exacerbated mitochondrial dysfunction, weakened cytoskeletal proteins, accelerated early apoptosis. Consequently, both survival and maturation rates were markedly reduced. Interestingly, PI3K/AKT activation increased AQP7 expression, restored abnormal mitochondrial distribution, as well as calcium homeostasis, and rescued the oocyte survival/maturation rate. Conclusions: Our results provide new insights indicating that PI3K/AKT/AQP7 decreases oxidative stress by regulating mitochondrial morphology, function, and distribution, thereby rescuing oocyte maturation in vitrification.

The cryopreservation of Chengde polled goat semen plays a critical role in conserving genetic resources, enhancing the utilization efficiency of superior breeding bucks, and advancing artificial insemination techniques. However, spermatozoa are vulnerable to oxidative stress during the freezing process, which can significantly compromise sperm motility. In this study, pooled ejaculates from multiple bucks were divided into six groups, including a control group cryopreserved with conventional extender and five treatment groups supplemented with sericin at concentrations of 0.2%, 0.4%, 0.6%, 0.8%, and 1.0% (w/v). The results demonstrated that supplementation of the semen cryoprotectant with 0.6% sericin significantly improved post-thaw sperm viability to 65.25% in Chengde hornless goats, while concurrently reducing both the sperm abnormality rate (p < 0.05) and intracellular ROS levels (p < 0.05). Integrated TMT proteomics and LC/MS metabolomics further compared the 0.6% sericin group with the frozen control group and identified 162 differentially expressed proteins and 109 differential metabolites between the sericin supplementation and frozen control groups. Functional analysis revealed the significant enrichment of differential metabolites, such as glutamine, in the alanine, aspartate, and glutamate metabolism pathway, concomitant with the marked upregulation of antioxidant proteins including LRP8, GSTM3, and SIRT2. Thus, 0.6% sericin enhances cryotolerance primarily by improving sperm viability, reducing oxidative damage, and sustaining energy metabolism. These findings indicate that sericin enhances cryotolerance by reducing oxidative damage and supporting metabolic function, providing preliminary molecular insights for improving goat semen cryopreservation.

Oocyte vitrification imposes oxidative stress that compromises maturation competence. Aquaporin-7 (AQP7) has been implicated in cellular redox regulation, but its specific role in cryopreserved oocytes remains unclear. Here, germinal vesicle (GV) stage oocytes were vitrified and warmed with AQP7 inhibitor Z433927330 (0.5, 5, 50 μM). AQP7 inhibition disrupted redox balance, compromised mitochondrial function. Consequently, it severely compromised developmental competence, leading to significantly reduced cleavage (39.90% ± 6.17 vs. 52.93% ± 3.37) and blastocyst formation rates (1.67% ± 2.89 vs. 5.17% ± 2.49) in vitro. To confirm, we performed microinjection-mediated AQP7 knockdown and overexpression and assessed their effects on maturation. AQP7 knockdown further reduced the maturation rate of vitrified oocytes (20.22% ± 3.14 vs. 36.31% ± 2.10), whereas overexpression partially restored it (43.98% ± 4.71 vs. 33.74% ± 2.21). The mitochondrial-targeted antioxidant MitoQ partially rescued the maturation rate (53.13% ± 2.75 vs. 43.52% ± 2.71). Thus, AQP7 is essential for the maturation of vitrified sheep oocytes by safeguarding intracellular redox homeostasis, thereby preventing mitochondrial dysfunction and cytoskeletal damage, and loss of embryonic developmental potential.