Expression of Heat Shock Protein (HSP A1A) and MnSOD Genes Following Vitrification of Mouse MII Oocytes with Cryotop Method

Objective: the aim of this study was to investigate the effects of two vitrification protocolson mouse metaphase stage ii (mii) oocytes and evaluate their effects on the expressionof heat shock protein a1a (hsp a1a) and mnsod genes.materials and methods: groups of approximately 15 oocytes without cumulus complexeswere collected and vitrified with 10% (v/v) ethylene glycol (eg) + 10% (v/v) dimethylsulphoxide(dmso) + 0.5m sucrose in group a (vsi) and 14.5% (v/v) eg + 14.5% proh+ 0.5m sucrose in group b (vsii), respectively. thawing after vitrification was performdby placing the oocytes into 1m sucrose for 1 minute and two diluted solutions, each for3 minutes. after thawing, the oocytes were fertilized and cultured in vitro to develop intothe pronuclear stage. the survival rate of vitrified-warmed oocytes and rate of fertilizationwere evaluated. in addition, gene expressions (hsp a1a, mnsod and β actin) of vitrifiedwarmedoocytes were also examined by reverse transcription polymerase chain reaction(rt-pcr).results: survival rates of each group were separately compared to the control. the resultshowed significant differences between each experimental group compared to the control(p≤ 0.001). the survival rate of oocytes after warming was higher in vsi (91.2% ± 1.7)compared to vsii (89.2% ± 1.5) but there were no significant differences between the twogroups. the rate of fertilization was significantly (p≤0.05) reduced in vitrified-warmed (vsi:39% ± 5.8; vsii: 34% ± 5.7) oocytes compared to the control (88.36% ± 2.3). the expressionof mnsod increased in the vitrified-warmed oocytes when compared to controloocytes. we also detected hsp a1a only in the control and vsi group.conclusion: vitrification of oocytes by cryotop resulted in high survival rate; low developmentalcompetence and fertilization rate of vitrified-warmed oocytes which may be a resultof changing expression of important genes after thawing