The Effect of Roscovitine on Meiosis of Sheep Oocyte

Abstract

Improved in vitro methods are required to synchronize meiotic resumption and to<br><br>allow all collected oocytes to complete nuclear maturation without affecting oocyte<br><br>quality in order to maximize embryo production. The use of physiological or<br><br>pharmacological inhibitors can thus be envisaged. Roscovitine (ROS), as a selective<br><br>cdc2 inhibitor, has been reported to inhibit MPF and MAP kinase activity and<br><br>maintains the oocyte at Germinal Vesicle (GV) stage. The aim of the present study<br><br>was to investigate the effects of ROS on nuclear maturation of sheep oocytes. So,<br><br>different concentrations of ROS (6.25, 12.5 and 25 lM) added to maturation medium.<br><br>After 26 h exposition to ROS, the results indicated that the percentage of oocytes at<br><br>GV stage was 2.41, 2.29 and 8.39% for 6.25, 12.5 and 25 lM Roscovitine<br><br>concentration, respectively. Also, percentage of oocytes at MII stage was<br><br>significantly (p,0.05) higher in control group oocytes (75.3%) than in oocytes<br><br>exposed to 12.5 and 25 lM ROS (30.77 and 7.5 respectively). To evaluate if this<br><br>effect was reversible and if a retardation or inhibition had occurred in the progression<br><br>from GV to MII, oocytes were cultured in presence of the same concentrations of<br><br>ROS for 26 h followed by culture for an additional 24 h in medium without ROS.<br><br>After 50 h, the results showed that the oocytes can promote to MII. According to<br><br>these results, roscovitine can postpone meiosis of sheep oocyte and it may improve<br><br>cytoplasmic maturation and subsequently embryo production.