Enhanced glutathione production protects against zearalenone-induced oxidative stress and ferroptosis in female reproductive system.

Zearalenone (ZEN, a widespread fusarium mycotoxin) causes evoked oxidative stress in reproductive system, but little is known about whether this is involved in ferroptosis. Melatonin, a well-known antioxidant, has demonstrated unique anti-antioxidant properties in several studies. Here, this study was aimed to investigate whether ZEN-induced oxidative stress in female pig's reproductive system was involved in ferroptosis, and melatonin was then supplemented to protect against ZEN-induced abnormalities in vitro cell models [human granulosa cell (KGN) and mouse endometrial stromal cell (mEC)] and in vivo mouse model. According to the results from female pig's reproductive organs, ZEN-induced abnormalities in vulvar swelling, inflammatory invasion and pathological mitochondria, were closely linked with evoked oxidative stress. Using RNA-seq analysis, we further revealed that ZEN-induced reproductive toxicity was due to activated ferroptosis. Mechanistically, by using in vitro cell models (KGN and mEC) and in vivo mouse model, we observed that ZEN exposure resulted in oxidative stress and ferroptosis in a glutathione-dependent manner. Notably, these ZEN-induced abnormalities above were alleviated by melatonin supplementation through enhanced productions of glutathione peroxidase 4 and glutathione. Herein, the present results suggest that potential strategies to improve glutathione production protect against ZEN-induced reproductive toxicity, including oxidative stress and ferroptosis.

Selenium supplementation during in vitro maturation enhances meiosis and developmental capacity of yak oocytes.

The objectives of the present study were to investigate the effects of selenium (Se) supplementation during in vitro maturation (IVM) on the developmental capacity of yak (Bos grunniens) oocytes. Nuclear maturation, DNA integrity, glutathione peroxidase (GSH-Px) activity, subsequent embryonic development, and gene expression after in vitro fertilization (IVF) were evaluated. The Se concentrations in yak plasma and follicular fluid were 0.142 and 0.069 µg/mL, respectively. The DNA damage in cumulus cells decreased significantly with 2 and 4 µg/mL supplementation of sodium selenite to IVM medium (P < 0.05). Total GSH-Px activity in oocytes increased in all Se supplementation groups, and the 2 and 4 µg/mL groups were significantly higher than the control group (0 µg/mL). However, the cleavage rate was not significantly different after Se supplementation (P > 0.05). The IVF blastocyst formation rates of 0, 1 and 4 µg/mL sodium selenite groups were 47.7%, 51.2% and 58.9%, respectively. The 2 µg/mL sodium selenite group had the highest blastocyst formation rate (60.5%). Gene expression analysis revealed that the quantity of transcripts associated with selenoprotein and protein synthesis were high in the 2 and 4 µg/mL groups. In conclusion, both GSH-Px activity of oocytes and DNA integrity of cumulus cells significantly increased with supplemental Se during oocyte IVM. Considering that embryonic development is responsive to Se supplementation, we inferred that appropriate Se concentrations during IVM were beneficial for yak oocyte maturation and subsequent development.

Effects of Zinc Supplementation During In Vitro Maturation on Meiotic Maturation of Oocytes and Developmental Capacity in Yak.

Zinc (Zn) is an essential trace element that is required during mammalian developmental processes. The objective of this study was to investigate the effects of Zn supplementation during in vitro maturation (IVM) on the developmental capacity of yak (Bos grunniens) oocytes. Cumulus expansion, nuclear maturation, intracellular glutathione (GSH), reactive oxygen species (ROS) levels, superoxide dismutase (SOD) activity, subsequent embryonic development, and the expression of Zn transporters (ZnTs) and Zrt and Irt-like proteins (ZiPs) were evaluated. The Zn concentrations in yak plasma and follicular fluid were 0.740 ± 0.012 and 0.382 ± 0.009 µg/mL, respectively. The cumulus expansion did not show significant differences in COCs after matured with or without Zn supplementation (P > 0.05). The intracellular GSH was higher in oocytes matured with 1 or 2 mg/L Zn than in control group (0 mg/L) (P < 0.05). However, ROS levels of oocytes matured with 1 or 2 mg/L Zn were reduced significantly compared with the control and 0.5 mg/L groups (P < 0.05). The SOD activity was increased significantly after Zn supplementation. The cleavage rate was not significantly different after Zn supplementation (P > 0.05). Percentages of matured oocytes that developed into the blastocyst stage after IVF were 47.9, 50.5, 60.4, and 58.9% for 0, 0.5, 1, and 2 mg/L Zn groups, respectively. Gene expression analysis revealed that the expression patterns associated with Zn were changed after Zn supplementation. In conclusion, Zn supplementation to IVM improved yak oocyte maturation and subsequent development by increasing GSH and SOD activity, decreasing ROS in oocytes.