Pterostilbene exerts a protective effect via regulating tunicamycin-induced endoplasmic reticulum stress in mouse preimplantation embryos

The Beneficial Effects of Pterostilbene on Post-Thawed Bovine Spermatozoa

Reactive Oxygen Species (ROS), primarily produced by cellular metabolism, are highly reactive molecules that modify cellular compounds. During sperm preparation in Assisted Reproductive Techniques (ARTs), intrinsic and extrinsic sources of ROS can impact spermatozoa's oxidative status. The modification of the media with compounds that enhance sperm quality characteristics is of great significance. The current study investigated the effect of pterostilbene, a phenolic compound, on bovine sperm quality. Cryopreserved spermatozoa from six bulls were thawed, supplemented with pterostilbene (0, 10 μΜ, 25 μΜ) and incubated for 60 min and 240 min. Spermatozoa were analyzed in terms of motility, viability, acrosomal status and intracellular concentration of superoxide anion in each time point. The incubation of spermatozoa with 25 μΜ pterostilbene resulted in the preservation of quality parameters through superoxide anion mitigation, while its presence in capacitating conditions resulted in higher percentage of acrosome-reacted spermatozoa. The results of the present study indicate that the addition of pterostilbene prevents oxidative insult to spermatozoa and preserves the sperm quality parameters.

Apigetrin ameliorates streptozotocin-induced pancreatic β-cell damages via attenuating endoplasmic reticulum stress

The pathogenesis of diabetes is associated with dysfunction of pancreatic β-cells. To ameliorate the β-cell dysfunction, it has propelled great interest to search pharmacological agents from natural plants. This study explored the protective effect of apigetrin, a flavonoid present in natural plants, against streptozotocin (STZ)-induced cell damages in RINm5F cells and the potential mechanisms. Apigetrin was found to inhibit the elevation of intracellular reactive oxygen species levels, restore the impairment of antioxidant enzymes, and recover the disruption of redox homeostasis in the STZ-treated pancreatic β-cells. Moreover, treatment of apigetrin significantly suppressed the STZ-induced apoptosis in the analysis of apoptotic sub-G₁ population and the protein expressions of cleaved poly(ADP-ribose) polymerase and caspase-3. Furthermore, apigetrin attenuated STZ-induced endoplasmic reticulum (ER) stress, indicated by the reduction of ER stress biomarkers, including overloading of mitochondrial calcium, increase in glucose-regulated protein 78, phosphorylation of protein kinase RNA-like ER kinase and its downstream eukaryotic initiation factor 2α, cleavage of activating transcription factor 6 and caspase-12, up-regulation of CCAAT/enhancer binding protein homologous protein, and induction of spliced X-box binding protein 1. Additionally, pretreatment with 4-phenylbutyric acid, a classic ER stress inhibitor, augmented these beneficial effects of apigetrin. In conclusion, these results demonstrated that apigetrin could improve the STZ-induced pancreatic β-cell damages via mitigation of oxidative stress and ER stress and supported the application of apigetrin to developing the novel therapeutics of diabetes.

Effect of pterostilbene on development, equatorial lipid accumulation and reactive oxygen species production of in vitro-produced bovine embryos

The pterostilbene (PT) molecule is a phytoalexin with a reducing effect on reactive oxygen species (ROS) and with a capacity to block lipogenesis. However, the potential reducing effects of PT on equatorial lipid accumulation and ROS have not yet been elucidated for in vitro-derived bovine embryos. The present study evaluated the effects of concentrations of 3, 1, 0.33, 0.11 μM PT, and a vehicle group on the percentage of cleaved embryos, embryos with more than 6 cells, percentage of blastocyst on Day 7 and 8, percentage of transferable embryos on Day 7, the cell count and relative concentration of lipids. In the second experiment, the effects of 0.33 μM PT and a vehicle group within two different O₂ environments (5% and 20%) were evaluated for ROS generation and the percentage of Day 8 blastocysts. In the first experiment, no significant differences were found between the treatments with PT and the vehicle group (p > .05) concerning the percentage of cleaved embryos and embryos with more than 6 cells. Lipid reduction was observed in the groups treated with PT versus the vehicle group (p < .05). The vehicle group showed a higher rate of blastocyst production on Days 7 and 8 (p < .05) and an increase in the percentage of transferable embryos on Day 7 compared to the PT treatment groups (p < .05). Cell counts were not significantly different between treatments with PT and the vehicle group (p > .05). In the second experiment, the O₂ concentration did not significantly affect ROS generation (p > .05); however, the groups treated with PT (0.33 μM) had a reduction in ROS (p < .05). The O₂ concentration also did not significantly affect the rate of blastocyst production on Day 8 (p = .7696). Future research should be conducted to ascertain whether the reduction of lipids could enhance the cryopreservation and post-thaw viability of PT-treated embryos.

Tauroursodeoxycholic acid (TUDCA) enhanced intracytoplasmic sperm injection (ICSI) embryo developmental competence by ameliorating endoplasmic reticulum (ER) stress and inhibiting apoptosis

PURPOSE

The objective of this study was to examine the effect of tauroursodeoxycholic acid (TUDCA) on intracytoplasmic sperm injection (ICSI) embryos by evaluating endoplasmic reticulum (ER) stress, apoptosis, and embryo developmental competence in vitro and in vivo.

METHODS

ER stress-associated genes and apoptosis-associated genes were measured and apoptosis index was analyzed. Embryo developmental competence was assessed in vitro and in vivo via the inner cell mass (ICM)/trophectoderm (TE) index, pregnancy and implantation rates, and birth rate.

RESULTS

The relative mRNA and protein expression of binding immunoglobulin protein (BIP) was significantly higher in the ICSI embryo group without TUDCA treatment (ICSI-C) than in the in vitro fertilization (IVF) group and in the ICSI embryo group with TUDCA treatment (200 μM) (ICSI-T), while TUDCA ameliorated ER stress in ICSI embryos. Embryos in the ICSI-C group showed a higher apoptosis index than those in the IVF group and ICSI-T group, and there was no significant difference between the IVF group and ICSI-T group. TUDCA can significantly improve ICSI embryo developmental competence in vitro and in vivo based on the ICM/TE index, pregnancy and implantation rates, and birth rate.

CONCLUSION

ICSI embryos manifested high ER stress and high apoptosis, while TUDCA ameliorated ER stress and reduced apoptosis in ICSI embryos. TUDCA can significantly improve the developmental competence of ICSI embryos in vitro and in vivo. This study provides a new idea for improving the efficiency of ICSI, and it will also have a positive effect on the development of assisted reproduction technologies for humans and other animals.