Effects of Roscovitine in maintaining meiotic arrest in equine oocytes and subsequent maturation rates after inhibition

摘要

Oocyte maturation involves a series of distinct and interdependent changes that occur in the nucleus and cytoplasm of oocytes. Recently, more attention has been paid to establishing systems that would favor the ideal synchronicity between nucleus and cytoplasmic maturation. The concept of allowing cytoplasmic maturation, while nuclear maturation is blocked, has been successfully tested with protein synthesis inhibitors [1,2] and phosphorylation inhibitors [3,4]. These agents are effective and fully reversible but blastocyst formation is affected. Among the specific kinase inhibitors, Roscovitine and Butyrolactone-1 were capable of inhibiting germinal vesicle breakdown (GVBD) in bovine oocytes for 24 h without compromising further developmental competence [5,6]. Roscovitine has not yet been proved to be effective in the equine (Hinrichs, personal communication). Other meiotic inhibitors such as DMAP and cycloheximide were determined to be effective in the horse [7,8] and similarly to other species, such as the bovine, have low reversibility with potential influence in further development after withdrawal. The objective of Experiment 1 was to determine the effective dose of Roscovitine to inhibit progression of meiotic maturation in equine oocytes, and of Experiment 2, to evaluate the reversibility of this block after 24 or 32 h of incubation with the inhibitor.