Effect of Cryopreservation on Atp Content of Ovulated Rabbit Oocytes

Oocytes cryopreservation represents a very promising tool for medicine and preservation of animal genetic resources. Assessment of oocytes viability after cryopreservation is often based on structural and developmental criteria whereas metabolism of thawed oocytes is not frequently studied. The aim of this study was to evaluate the impact of slow freezing and vitrification methods on the ATP concentration in ovulated rabbit oocytes. ATP contents of oocytes were evaluated by measurement of light emission intensity during the ATP-dependent oxidation of luciferin by luciferase. ATP levels were compared between frozen and vitrified oocytes after 2 hours of in vitro culture and fresh oocytes as a control. Independently of the cryopreservation method used, ATP content per cell was significantly (P<0.001) lower for cryopreserved oocytes as compared to fresh ones (6.34±0.39 pmol of ATP per fresh oocyte). Frozen oocytes showed a significantly (P<0.001) lower ATP metabolism than the vitrified ones (2.93±0.23 and 4.88±0.21 pmol of ATP per frozen and vitrified oocyte respectively). In conclusion, this study shows that ATP assay is an attractive tool to evaluate the viability of cryopreserved oocytes. Moreover, according to these results, vitrification seems to be a more suitable method than slow freezing to cryopreserve ovulated rabbit oocytes.