Effects of Preservation of Porcine Oocytes by Dibutyryl Cyclic AMP on in vitro Maturation, Fertilization and Development

In this study, the effects of dibutyryl cyclic AMP (dbcAMP) on the preservation of porcine oocytes were investigated. Oocytes were preserved for 24 h or 48 h in modified NCSU37 supplemented with or without 1 mM dbcAMP. After the preservation, 98.3% and 95.2% of oocytes incubated with dbcAMP for 24 h and 48 h, respectively, were at the germinal vesicle stage, whereas about a half of the oocytes incubated without dbcAMP underwent germinal vesicle break down. These preserved oocytes were cultured for 46 h. The in vitro maturation (IVM) rates of oocytes preserved with dbcAMP for 24 h (84.0%) and 48 h (55.3%) were significantly higher than those of oocytes preserved without dbcAMP (48.0% and 21.6%, respectively). IVM oocytes with a visible first polar body were selected, fertilized in vitro (IVF), and cultured for five days. The rate of oocytes preserved for 24 h with dbcAMP and developed to the blastocyst stage after IVF was 21.4% and did not differ from that of oocytes without preservation (23.8%); however, the blastocyst development rate significantly decreased for oocytes preserved with dbcAMP for 48 h (5.2%). These results indicate that dbcAMP is effective for the preservation of porcine oocytes for 24 h without decreasing their developmental ability after IVF.