1. The effects of glutathione ethyl ester in in vitro maturation on the developmental ability of oocytes derived from cattle with liver abnormalities
Borjigin Sarentonglaga, Shiori Ashibe, Taiki Kato, Khurchabiling Atchalalt, Rika Fukumori, Yoshikazu Nagao Theriogenology. 2021 Aug;170:85-90. doi: 10.1016/j.theriogenology.2021.05.003. Epub 2021 May 6.
The main objectives of this study was to identify the effects of a relationship of hyper-concentration of Gamma-glutamyltransferase (γ-GTP) in follicle fluid (FF) on the levels of glutathione (GSH)/reactive oxygen species (ROS) in oocytes and subsequent embryo development in cattle with abnormal livers. Furthermore, we investigated the effect of supplementing in vitro maturation medium with glutathione ethyl ester (GSH-OEt) on the subsequent developmental potential of oocytes from such cattle. We used a control group of cattle (with normal livers) and a liver disorder (LD) group, in which the liver was diagnosed as being abnormal. In experiment 1, the LD group was divided to two subgroups according to the concentration of γ-GTP in FF: a low group (≤50 IU/L; the low LD group), and a high group (>50 IU/L: the high LD group). Cumulus oocyte-complexes (COCs) were matured and fertilized in vitro and then cultured to the blastocyst stage. The levels of GSH and ROS in the matured oocytes after IVM were then assessed in each group. On day 7 after fertilization, embryo cleavage and development were assessed. We found that the rate of development to the blastocyst stage was significantly lower in the high LD group than in the control group and the low LD group. The levels of GSH in matured oocytes were significantly lower in the high LD group than in the control group and low LD group. The levels of ROS in matured oocytes was significantly higher in the high LD group than in the control group and the low LD group. In experiment 2, COCs from cattle in the high LD group were matured in m-199 supplemented with 5 mM GSH-OEt, then IVF and IVC was performed for 7 days. The GSH levels were determined in some COCs after IVM. The supplementation of media with GSH-OEt during IVM increased the levels of GSH in mature oocytes and improved the rate of blastocyst development compared with the control group. In conclusion, GSH-OEt supplementation to media during IVM can improve the developmental potential of oocytes in liver-diseased cattle with high γ-GTP concentrations in the FF by increasing intracellular GSH synthesis and scavenging ROS.
2. Glutathione ethyl ester improved the age-induced decline in the developmental competence of bovine oocytes
F Magata, A Ideta, F Matsuda, M Urakawa, Y Oono Theriogenology. 2021 Jun;167:37-43. doi: 10.1016/j.theriogenology.2021.03.004. Epub 2021 Mar 10.
The aberrant redox regulation and anti-oxidative defense is one of the main causes of age-induced decline in oocytes quality and embryo development in mammals. The present study aimed to elucidate the effect of glutathione ethyl ester (GSH-OEt), a cell-permeable glutathione (GSH) donor, on the developmental competence of oocytes in cows with advanced reproductive age. Oocytes were collected from cows aged 30-50 months or >120 months, which were defined as young or aged, respectively, and subjected to in vitro maturation (IVM) in the presence of 5 mM of GSH-OEt. In aged cows, the GSH level in follicular fluid was lower, and the intracellular levels of reactive oxygen species (ROS) in post-IVM oocytes was higher than those in young cows. GSH-OEt supplementation during IVM reduced the ROS contents of oocyte in aged cows but not in young cows. GSH-OEt treatment promoted the meiotic progression and increased the proportion of oocytes with mature cytoplasm containing evenly dispersed cortical granules in aged cows. After in vitro fertilization, the normal fertilization and development to the blastocyst stage were enhanced by GSH-OEt in aged cows to levels comparable to those in young cows. Further, oocyte maturation in the presence of GSH-OEt increased the proportion of diploid blastocyst in aged cows. In contrast, GSH-OEt failed to enhance the oocyte maturation, fertilization, and embryo development in young cows. Taken together, the exogenous supplementation of GSH-OEt during IVM modulated the age-related oxidative damage of bovine oocytes and improved the developmental competence of oocytes in aged cows. Oocytes presented a distinct response to GSH-OEt treatment depending on the donor age. GSH-OEt supplementation during IVM could be of practical value through the efficiency improvement of chromosomally normal embryo production in aged cows.
3. Glutathione ethyl ester supplementation prevents airway hyper-responsiveness in mice
Qiaoyun Wang, Aimin Li, Yiqiong Zheng, Shu Zhang, Ping Wang Ann Transl Med. 2020 Nov;8(22):1519. doi: 10.21037/atm-20-7114.
Background: Oxidative stress plays an important role in the pathogenesis of asthma. Glutathione (GSH) is considered to be one of the most important antioxidants. Our study systematically investigated the effect of the GSH alternative, glutathione ethyl ester (GSH-EE), on airway hyper-responsiveness (AHR) in mice. Methods: Sixty-three male specific pathogen-free mice were used. Asthma was induced using a single dose of ovalbumin (OVA). The normal group (n=15) received vehicle only [Al(OH)3 in saline]. Then, 48 mice were divided into two groups, including a control group who received sodium phosphate buffer (pH =7.4), and the GSH-EE group who received 0.1% GSH-EE. AHR was measured 2, 6, and 12 hours after exposure to nebulized OVA (0.01%). The animals were then sacrificed, and lung tissue and the bronchi-alveolar lavage fluid (BALF) were harvested. Factors involved in the antioxidant response to asthma were then measured in these tissues, including thiol content (from GSH and protein), γ-glutamylcysteine synthetase (γ-GCS) activity and expression, and nuclear factor-erythroid-2-related factor (Nrf2) expression. Results: The GSH-EE group showed a significant attenuation of AHR (P0.05) between the GSH-EE group and the control group. Conclusions: GSH-EE supplementation can prevent AHR in asthmatic mice during the early stages. It may function by serving as a precursor for GSH biosynthesis and by protecting sulfhydryl groups from oxidation.
