The effect of docetaxel on survival, fertilization rate and apoptosis-related genes mRNA expression in mouse metaphase II oocytes following vitrification

Background: Docetaxel is beneficial in oocyte cryopreservation. Aims: The effect of docetaxel, on the survival, fertilization rate and mRNA expression of apoptosis-related genes of vitrified mature oocytes was investigated. Methods: Mature oocytes were divided into eight experimental groups, including I) control, II) docetaxel, III) docetaxel + cryoprotectant agent 1 (CPA1), IV) docetaxel + CPA2, V) docetaxel + vitrification 1 (Vit1), VI) docetaxel + Vit2, VII) Vit1, and VIII) Vit2. The survival and fertilization rates, and the mRNA expression level of Bcl-xl, Bax and caspase-3 as apoptosis-related genes were evaluated. Results: The survival rates in Vit1, and Vit2 groups were significantly lower than in the control group (P<0.05). The fertilization rates in docetaxel + Vit1, docetaxel + Vit2, Vit1, and Vit2 were significantly lower than the control, docetaxel, and related groups using docetaxel and CPAs. Bax expression was significantly increased in groups which oocytes vitrified. Also, its expression in the Vit2 group increased significantly in comparison to the docetaxel + Vit2 group. The expression of the Bcl-xl gene was downregulated in docetaxel + CPA2, docetaxel + Vit2 and Vit2 compared to docetaxel group. The Bax/Bcl-xl ratio significantly increased in docetaxel + CPA2, docetaxel + Vit1, docetaxel + Vit2, Vit1 and Vit2 groups compared to control, docetaxel and the docetaxel + CPA1 group. Caspase-3 expression significantly increased in all six groups in comparison to the control, and docetaxel groups. Its expression significantly increased in the Vit1 and Vit2 groups in comparison with docetaxel + Vit1, and docetaxel + Vit2, respectively. Conclusion: Docetaxel ameliorates the damages to oocytes during vitrification by altering the expression of apoptosis-related genes and its effects are dependent on the vitrification solution used in cryopreservation of oocytes.