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.

Developmental potential of sheep oocytes cultured in different maturation media: effects of epidermal growth factor, insulin-like growth factor I, and cysteamine

“…These results are in agreement with other reports showing that supplementation with Cys during IVM did not influence the rate of cleavage (40,41) but enhanced embryo development (9,10,17,42). Several studies have shown that Cys increases cytoplasmic glutathione levels in bovine and ovine oocytes (17,20,43,44) and that Cys has a positive influence on embryo development (44). It is likely that the enhanced glutathione concentration promotes early embryo development by facilitating the completion of oocyte cytoplasmic maturation (10,41,42).…”

“…Gasparrini et al (41) showed that supplementation with Cys during IVM of buffalo oocytes significantly enhanced cytoplasmic glutathione content after maturation and subsequently improved embryo development. A study by de Matos et al (44) showed a positive effect of Cys in IVM on blastocyst development in adult mice, but this effect was not observed in oocytes recovered from prepubertal mice. Furthermore, Abeydeera et al (7) and Brad et al (47) reported no significant difference between the rate of nuclear maturation of porcine oocytes matured in UDMM (medium containing follicular fluid) versus those matured in DMM supplemented with Cys and EGF.…”

“…It is likely that the enhanced glutathione concentration promotes early embryo development by facilitating the completion of oocyte cytoplasmic maturation (10,41,42). In ewes, 200 mmol/L Cys in the maturation medium increased blastocyst production (44), and in goats, the addition of 100-200 200 mmol/ L Cys during IVM improved cleavage and the embryo development rate (45,46). Gasparrini et al (41) showed that supplementation with Cys during IVM of buffalo oocytes significantly enhanced cytoplasmic glutathione content after maturation and subsequently improved embryo development.…”

Glutathione Content of In Vivo and In Vitro Matured Canine Oocytes Collected from Different Reproductive Stages

“…cattle [8], pigs [1], mice [9]. In the present study, β-mercaptoethanol significantly increased GSH content in follicular and luteal oocytes during IVM.…”

Effects of in vitro maturation of monkey oocytes on their developmental capacity

“…In cattle and pigs, oocytes from prepubertal donors display poor meiotic maturation and embryo development compared to oocytes from adult females (Marchal et al, 2001;Salamone et al, 2001;de Matos et al, 2003;Grupen et al, 2003;Sherrer et al, 2004). Consistent with their lesser meiotic and developmental potential, oocytes from sexually immature females display morphological, biochemical and physiologic alternations or anomalies that could partially account for their reduced competence.…”