Capacity of adult and prepubertal mouse oocytes to undergo embryo development in the presence of cysteamine.
ABSTRACT The present study was carried out to study de novo glutathione (GSH) synthesis and to evaluate the effect of stimulating GSH synthesis during in vitro maturation (IVM) of adult and prepubertal mouse oocytes on the embryo developmental rate. Adult (8 weeks old) and prepubertal mice (24-26 days old) were primed with 5 IU of PMSG and oocytes were retrieved from the ovary 48 hr later for IVM. After IVM (18 hr) Cumulus oocyte complexes (COC) were in vitro fertilized (IVF) and in vitro culture (IVC) in order to observe embryo development. The IVM medium was supplemented with: 0, 25, 50, 100, or 200 microM of cysteamine. To study the novo GSH synthesis, 5 mM BSO was added during IVM of adult or prepubertal oocyte. Developmental rates up to blastocyst were recorded for each group. Experiments also included a group of ovulated oocytes (in vivo matured) after priming with PMSG and HCG. After IVM of adult mice oocytes, an improvement was observed on embryo development in all the supplemented groups when compared with the untreated group (P < 0.05). No differences were observed in blastocyst rate among IVM oocytes with cysteamine and ovulated oocytes. Prepubertal IVM mouse oocytes had a lower cleavage rate compared with ovulated oocytes (P < 0.05). Cysteamine failed to improve prepubertal oocytes developmental rates (P > 0,05). 2-cell embryos, coming from IVM prepubertal oocytes and ovulated oocytes had the same preimplantation developmental rate up to the blastocyst stage. In prepubertal, and adult oocytes an inhibition of embryo development was observed when buthionine sulfoximide (BSO), a specific inhibitor of the gamma-glutamylcysteine synthetase, was added during oocyte maturation (P < 0.01). In conclusion, an improvement in mouse embryo development was observed when cysteamine was added to the IVM medium of adult mice oocytes. In prepubertal oocytes cysteamine addition during oocyte maturation failed to improve embryo developmental rates. The presence of BSO lowered or completely blocked blastocyst development. This proves that, de novo GSH synthesis during oocyte maturation of adult and prepubertal oocytes undoubtedly plays an important role in embryo development. The improvement on oocyte competence observed in adult mice oocytes is probably related to intracellular GSH synthesis stimulated by cysteamine. Nevertheless the reason why cysteamine failed to improve prepubertal oocytes competence remains as an open question.
Article: Effect of dietary protein level and origin on the redox status in the digestive tract of mice.[show abstract] [hide abstract]
ABSTRACT: The present study was undertaken to evaluate the effects of high protein (soybean protein or casein) on the balance between production of free radicals and antioxidant level in digestive organs of mice. For this purpose, male (C57BL/6J) mice were adapted to experimental diets containing soybean protein or casein with 20% (normal protein diets, NPDs) or 60% (high protein diets, HPDs), and HPDs supplemented with 0.06 g/kg cysteamine. After two weeks of feeding, oxidative and antioxidative parameters in duodenum, liver and pancreas were measured. The results show that ingestion of high protein markedly increased contents of superoxide anion and malondialdehyde (MDA), decreased activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) and Na(+) K(+)-ATPase, and content of reduced glutathione (GSH) in digestive organs of mice (P<0.05). Levels of oxidative parameters were lower and antioxidant capacity of both enzyme and non-enzyme was higher in mice fed with soybean protein than those fed with casein. In groups fed HPDs supplemented with cysteamine, oxidative stress was mitigated. However, oxidative parameter levels were still higher than those of NPD-fed groups. The present study indicates that ingestion of high protein diets could result in an imbalance between oxidant and antioxidant, and thus induce oxidative stress in digestive organs of mice. The oxidative damage was smaller in mice fed with high level of soy protein in comparison with casein.International Journal of Molecular Sciences 05/2008; 9(4):464-75. · 2.60 Impact Factor