Induction of Oxidative Stress and Mitochondrial Dysfunction by Juglone Affects the Development of Bovine Oocytes

Expression and significance of pin1 in the wound healing

The aim of this study is to delineate the expression patterns of prolyl cis-trans isomerase NIMA-interacting protein 1 (Pin1), Glial cell-derived neurotrophic factor (GDNF), and Angiotensin II (ANG II) during the process of wound repair, and to ascertain the effects of Pin1, GDNF, and ANG II on the healing of wounds in a rat model. A total of 18 rats were allocated into three groups-sham (control), DMSO (vehicle control), and Pin1 inhibitor (treatment with juglone)-with six animals in each group. An animal model of wound healing was established, followed by the intraperitoneal administration of juglone. Tissue samples from the wounds were subsequently collected for histopathological evaluation. Expression levels of Pin1, GDNF, and Ang II were quantified. In addition, an in vitro model of wound healing was created using human umbilical vein endothelial cells (HUVEC), to assess cell proliferation, migration, and tube formation under conditions of juglone pre-treatment. The expression levels of Pin1, GDNF, and ANG II were notably elevated on 7-, and 10- days post-wound compared to those measured on 3-day. Contrastingly, pre-treatment with juglone significantly inhibited the expression of these molecules. Histological analyses, including HE (Hematoxylin and Eosin), Masson's trichrome, and EVG (Elastic van Gieson) staining, demonstrated that vascular angiogenesis, as well as collagen and elastin deposition, were substantially reduced in the juglone pre-treated group when compared to the normal group. Further, immunohistochemical analysis revealed a considerable decrease in CD31 expression in the juglone pre-treatment group relative to the normal control group. Pin1 serves as a pivotal facilitator of wound repair. The findings indicate that the modulation of Pin1, GDNF, and ANG II expression impacts the wound healing process in rats, suggesting potential targets for therapeutic intervention in human wound repair.

Attenuation of Oxidative Stress and Regulation of AKT Signaling by Vanillic Acid during Bovine Pre-Implantation Embryo Development

Vanillic acid (VA) has shown antioxidant and anti-inflammatory activities in different cell types, but its biological effects in the context of early embryo development have not yet been clarified. In the current study, the impact of VA supplementation during in vitro maturation (IVM) and/or post-fertilization (in vitro culture; IVC) on redox homeostasis, mitochondrial function, AKT signaling, developmental competence, and the quality of bovine pre-implantation embryos was investigated. The results showed that dual exposure to VA during IVM and late embryo culture (IVC3) significantly improved the blastocyst development rate, reduced oxidative stress, and promoted fatty acid oxidation as well as mitochondrial activity. Additionally, the total numbers of cells and trophectoderm cells per blastocyst were higher in the VA-treated group compared to control (p < 0.05). The RT-qPCR results showed down-regulation of the mRNA of the apoptosis-specific markers and up-regulation of AKT2 and the redox homeostasis-related gene TXN in the treated group. Additionally, the immunofluorescence analysis showed high levels of pAKT-Ser473 and the fatty acid metabolism marker CPT1A in embryos developed following VA treatment. In conclusion, the study reports, for the first time, the embryotrophic effects of VA, and the potential linkage to AKT signaling pathway that could be used as an efficacious protocol in assisted reproductive technologies (ART) to improve human fertility.

Modulation of Apoptosis and Autophagy by Melatonin in Juglone-Exposed Bovine Oocytes

Melatonin, an antioxidant hormone secreted by the pineal gland, has been recognized as a regulator for numerous biological events. The deleterious effects of juglone, a polyphenolic extract of walnut trees, on embryo development has been previously reported. In the current study, we aimed to display the impact of melatonin administrated during in vitro oocyte maturation (IVM) on juglone-treated oocytes. Thus, in vitro matured oocytes were collected after 24 h post incubation with juglone in the presence or absence of melatonin. Reactive oxygen species (ROS), glutathione (GSH) content, mitochondrial distribution, and the relative abundance of mRNA transcription levels were assessed in oocytes, in addition, oocytes were in vitro fertilized to check the competency levels of oocytes to generate embryos. We found that administration of melatonin during the maturation of oocytes under juglone stress significantly improved the cleavage rate, 8-16 cell-stage embryos and day-8 blastocysts when compared to the sole juglone treatment. In addition, the fluorescence intensity of ROS increased, whereas the GSH decreased in juglone-treated oocytes compared to melatonin-juglone co-treated and untreated ones. Additionally, a significant increase in the mitochondrial aberrant pattern, the pattern that was normalized following melatonin supplementation, was observed following juglone administration. The mRNA analysis using RT-qPCR revealed a significant upregulation of autophagy and oxidative-stress-specific markers in the juglone-treated group compared to the co-treatment and control. In conclusion, the study reveals, for the first time, a protective effect of melatonin against the oxidative stress initiated following juglone treatment during the in vitro maturation of oocytes.

Treatments of Porcine Nuclear Recipient Oocytes and Somatic Cell Nuclear Transfer-Generated Embryos with Various Reactive Oxygen Species Scavengers Lead to Improvements of Their Quality Parameters and Developmental Competences by Mitigating Oxidative Stress-Related Impacts

This study investigated the antioxidant effects of β-cryptoxanthin (BCX), hesperetin (HES), and icariin (ICA), and their effects on in vitro maturation of porcine oocytes and subsequent embryonic development of somatic cell nuclear transfer (SCNT). Treatment with 1 μM BCX (BCX-1) increased the developmental rate of porcine oocytes more than treatment with 100 μM HES (HES-100) or 5 μM ICA (ICA-5). The glutathione level and mRNA expression of antioxidant genes (NFE2L2, SOD1, and SOD2) were more increased in the BCX-1 group than in the HES-100 and ICA-5 groups, while the reactive oxygen species level was more decreased. Moreover, BCX improved the developmental capacity and quality of SCNT embryos. The total cell number, apoptotic cell rate, and development-related gene expression were modulated in the BCX-1 group to enhance embryonic development of SCNT. These results show that the antioxidant effects of BCX enhance in vitro maturation of porcine oocytes and subsequent embryonic development of SCNT.

Downregulation of PI3K/AKT/mTOR Pathway in Juglone-Treated Bovine Oocytes

We have previously reported that juglone, a natural compound found in Juglandaceae with a wide range of biological activities, can reduces the developmental competence of bovine oocytes. In the current study, we investigated the possible mechanisms behind the toxicity of juglone and the relationship with PI3K/AKT/mTOR signaling during the in vitro maturation (IVM) of oocytes. Results show that oocyte exposure to juglone was associated with a significant decrease in filamentous actin (F-actin) accumulation. The RT-qPCR showed downregulation of the meiosis progression indicator GSK-3A, oocyte development marker BMP15, mitochondria fusion controlling MFN1, oxidative stress-related OGG1, and histone methylation-related EZH1, EZH2, SUZ12, G9a, and SUV39H2 genes in juglone-treated oocytes. In addition, glycolysis- (PFK1 and GLUT1), ATP synthesis- (ATPase8 and ATP5F1B), and OXPHOS-specific markers (SDHA and SDHD), as well as the oocyte survival regulators (SOD2, VEGF, and MAPK1) significantly decreased upon juglone treatment. Moreover, lower expression of PI3K, AKT, and mTOR was observed at the transcriptional and/or translational level(s). The autophagy markers LC3B and beclin-1 as well as the DNA damage-specific marker 8-OxoG displayed overexpression in juglone-exposed oocytes. Taken together, our results show that administration of juglone during the IVM can reduce the quality and developmental health of bovine oocytes through downregulation of the PI3K/AKT/mTOR pathway and its downstream signaling cascades.

Rotenone causes mitochondrial dysfunction and prevents maturation in porcine oocytes

Rotenone is a commonly used insecticidal chemical in agriculture and it is an inhibitor of mitochondrial complex Ⅰ. Previous studies have found that rotenone induces the production of reactive oxygen species (ROS) by inhibiting electron transport in the mitochondria of somatic and germ cells. However, there is little precise information on the effects of rotenone exposure in porcine oocytes during in vitro maturation, and the mechanisms underlying these effects have not been determined. The Cumulus-oocyte complexes were supplemented with different concentrations of rotenone to elucidate the effects of rotenone exposure on the meiotic maturation of porcine oocytes during in vitro maturation for about 48 hours. First, we found that the maturation rate and expansion of cumulus cells were significantly reduced in the 3 and 5 μM rotenone-treated groups. Subsequently, the concentration of rotenone was determined to be 3 μM. Also, immunofluorescence, western blotting, and image quantification analyses were performed to test the rotenone exposure on the meiotic maturation, total and mitochondrial ROS, mitochondrial function and biogenesis, mitophagy and apoptosis in porcine oocytes. Further experiments showed that rotenone treatment induced mitochondrial dysfunction and failure of mitochondrial biogenesis by repressing the level of SIRT1 during in vitro maturation of porcine oocytes. In addition, rotenone treatment reduced the ratio of active mitochondria to total mitochondria, increased ROS production, and decreased ATP production. The levels of LC3 and active-caspase 3 were significantly increased by rotenone treatment, indicating that mitochondrial dysfunction induced by rotenone increased mitophagy but eventually led to apoptosis. Collectively, these results suggest that rotenone interferes with porcine oocyte maturation by inhibiting mitochondrial function.

Acute and sub-acute oral toxicity assessment of 5-hydroxy-1,4-naphthoquinone in mice

5-hydroxy-1,4-naphthoquinone (5NQ) or juglone is a bioactive molecule found in walnuts and has shown therapeutic effects in various disease models. Limited information is available regarding the toxicity of 5NQ, thereby limiting the clinical development of this drug. In the present study, oral acute (50, 300 and 2000 mg/kg) and sub-acute toxicity (5, 15 and 50 mg/kg) was assessed in mice to evaluate the safety of 5NQ. The acute toxicity study identified 118 mg/kg as the point-of-departure dose (POD) for single oral administration of 5NQ using benchmark dose modeling (BMD). Repeated administration of 5NQ at doses of 15 and 50 mg/kg/day caused reduction in food consumption and body weight of mice along with alterations in liver and renal function. Histopathological assessment revealed significant damage to hepatic and renal tissues at all doses in the acute toxicity study, and at higher doses of 15 and 50 mg/kg in the sub-acute toxicity study. We observed dose dependent mortality in sub-acute toxicity study and the no observed adverse effect level (NOAEL) was established as < 5 mg/kg/day. Modeling the survival response in sub-acute toxicity study identified 1.74 mg/kg/day as the POD for repeated administration of 5NQ. Serum levels of aspartate aminotransferase (AST) were most sensitive to 5NQ administration with a lower limit of BMD interval (BMDL) of 1.1 × 10-3 mg/kg/day. The benchmark doses reported in the study can be further used to determine a reference dose of 5NQ for human risk assessment.

Oroxin A reduces oxidative stress, apoptosis, and autophagy and improves the developmental competence of porcine embryos in vitro

Oroxin A (OA) is a flavonoid isolated from Oroxylum indicum (L.) Kurz that has various biological activities, including antioxidant activities. This study aimed to examine the viability of using OA in an in vitro culture (IVC) medium for its antioxidant effects and related molecular mechanisms on porcine blastocyst development. In this study, we investigated the effects of OA on early porcine embryo development via terminal deoxynucleotidyl transferase dUTP nick-end labeling, 5-ethynyl-2'-deoxyuridine labeling, quantitative reverse transcription PCR, and immunocytochemistry. Embryos cultured in the IVC medium supplemented with 2.5 μM of OA had an increased blastocyst formation rate, total cell number, and proliferation capacity, along with a low apoptosis rate. OA supplementation decreased reactive oxygen species levels, while increasing glutathione levels. OA-treated embryos exhibited an improved intracellular mitochondrial membrane potential and reduced autophagy. Moreover, levels of pluripotency- and antioxidant-related genes were upregulated, whereas those of apoptosis- and autophagy-related genes were downregulated by OA addition. In conclusion, OA improves preimplantation embryonic development by reducing oxidative stress and enhancing mitochondrial function.

PIN1 Protects Hair Cells and Auditory HEI-OC1 Cells against Senescence by Inhibiting the PI3K/Akt/mTOR Pathway

A growing amount of evidence has confirmed the crucial role of the prolyl isomerase PIN1 in aging and age-related diseases. However, the mechanism of PIN1 in age-related hearing loss (ARHL) remains unclear. Pathologically, ARHL is primarily due to the loss and dysfunction of hair cells (HCs) and spiral ganglion cells (SGCs) in the cochlea. Therefore, in this study, we aimed to investigate the role of PIN1 in protecting hair cells and auditory HEI-OC1 cells from senescence. Enzyme-linked immunosorbent assays, immunohistochemistry, and immunofluorescence were used to detect the PIN1 protein level in the serum of ARHL patients and C57BL/6 mice in different groups, and in the SGCs and HCs of young and aged C57BL/6 mice. In addition, a model of HEI-OC1 cell senescence induced by H2O2 was used. Adult C57BL/6 mice were treated with juglone, or juglone and NAC, for 4 weeks. Interestingly, we found that the PIN1 protein expression decreased in the serum of patients with ARHL, in senescent HEI-OC1 cells, and in the cochlea of aged mice. Moreover, under H2O2 and juglone treatment, a large amount of ROS was produced, and phosphorylation of p53 was induced. Importantly, PIN1 expression was significantly increased by treatment with the p53 inhibitor pifithrin-α. Overexpression of PIN1 reversed the increased level of p-p53 and rescued HEI-OC1 cells from senescence. Furthermore, PIN1 mediated cellular senescence by the PI3K/Akt/mTOR signaling pathway. In vivo data from C57BL/6 mice showed that treatment with juglone led to hearing loss. Taken together, these findings demonstrated that PIN1 may act as a vital modulator in hair cell and HEI-OC1 cell senescence.