SYNERGISTIC EFFECT OF ETHANOL AND CYCLOHEXIMIDE ON ACTIVATION OF FRESHLY MATURED BOVINE OOCYTES

Bovine follicular oocytes were collected from ovarian antral follicles (2 to 7 mm in diameter) from slaughtered cattle. They were matured in vitro (IVM) for 23 to 24 h and then activated. In Experiment 1, 4 concentrations of ethanol were compared. The activation rates of oocytes were 4, 12, 36 and 27%, respectively, following exposure for 7 min to 0, 5, 7 and 10% ethanol. In Experiment 2, 7% ethanol was tested with exposure times of 0, 5, 7.5 and 10 min, and 6, 32, 27 and 33% of the oocytes were activated, respectively. In Experiment 3 the synergistic effect of ethanol and electric pulse was compared within 4 treatments: A) 7% ethanol alone, B) electric pulse alone, C) ethanol first and then electric pulse treatment, and D) electric pulse first followed by ethanol exposure. Of the oocytes activated, 37, 31, 28 and 51%, respectively, were from Treatments A through D. In Experiments 4 and 5 the possible synergistic effect of ethanol and a protein synthesis inhibitor, cycloheximide, was studied within 4 treatments: A) parthenogenetic control with no activation treatment, B) ethanol alone, C) cycloheximide alone, and D) ethanol treatment followed by cycloheximide. The oocyte activation rates in Experiment 4 in Treatments A through D, respectively, were 9, 44, 43 and 84%. Corresponding values for development of oocytes to the 2 to 8-cell stage after culture for 3 d (Experiment 5) were 9, 20, 14 and 45%, respectively (P<0.05). exposure to 7% ethanol for 5 min followed by incubation with cycloheximide was the best activation treatment for bovine IVM oocytes.