Research Paper Volume 10, Issue 12 pp 4093—4106

Putrescine delays postovulatory aging of mouse oocytes by upregulating PDK4 expression and improving mitochondrial activity

Figure 5. Effects of putrescine on PDK4 expression, oxidative stress, and apoptosis in the oocytes during postovulatory aging. (A) The effect of putrescine on PDK4 expression was tested by immunofluorescence, qPCR and Western blot. Putrescine rescued the downregulation of PDK4 at both the mRNA and protein levels in the aging oocytes. (B) The effects of putrescine on the ROS level and mitochondrial distribution in the aging oocytes. Putrescine significantly reduced the ROS level and the number of aggregated mitochondria in the aging oocytes. If PDK4 expression was downregulated by siRNA, the above effects of putrescine were significantly weakened. (C) The effect of putrescine on the MMP was related to mitochondrial activity. Putrescine significantly raised the MMP in the aging oocytes. However, this effect was blocked by siRNA-PDK4. (D) The effect of putrescine on the cleaved caspase 3 was related to apoptosis in the aging oocytes. Putrescine significantly inhibited the increased level of cleaved caspase 3 in the oocytes during postovulatory aging. This effect of putrescine was partially blocked by the downregulation of PDK4. *p<0.05, ** p<0.01.