Mitochondria-Targeted Antioxidant MitoQ Improves In Vitro Maturation and Subsequent Embryonic Development from Culled Cows

Abstract

The purpose of this study was to investigate the effects and mechanisms of MitoQ on the IVM of culled bovine oocytes and subsequent embryonic development. The results revealed that in comparison to the control group (0 µmol/L), the IVM rate (p < 0.05) and subsequent blastocyst rate (p < 0.05) of the low-concentration 1 and 5 µmol/L MitoQ treatment group were increased. The level of ROS (p < 0.05) in the MitoQ treatment group was decreased in comparison to the control group. Additionally, the level of GSH, MMP, ATP, and mt-DNA in the MitoQ treatment group was increased (p < 0.05) in comparison to the control group. The expression level of BAX was decreased (p < 0.05) in the MitoQ treatment group, and the BCL2, DNM1, Mfn2, SOD, and CAT were increased (p < 0.05). In conclusion, MitoQ improved mitochondrial dysfunction, increased mitochondrial activity during IVM, and reduced oxidative stress, resulting in increased IVM rates and subsequent embryonic development from culled cows.

Keywords: IVM; MitoQ; antioxidant; bovine oocytes; mitochondria; oxidative stress.

Figure 1

Influences of MitoQ on subsequent embryonic development and quality. Representative images of blastocyst development on day 7 for control group and (1, 5, 10 µmol/L) MitoQ treatment groups. Scale bar: 200 µm.

Figure 2

Influences of MitoQ on the ROS level in matured bovine oocytes. (A) Representative images of ROS (green) staining of oocytes in control group and MitoQ treatment group. Scale bar: 200 µm. (B) Analysis of ROS fluorescent intensity data. All experiments were performed in at least three replications, and the data statistics were represented by mean ± SEM. Values (a, b) with different superscripts in the columns are significantly different (p < 0.05).

Figure 3

Influences of MitoQ on the GSH level in matured bovine oocytes. (A) Representative images of GSH (blue) staining of oocytes in control group and MitoQ treatment group. Scale bar: 200 µm. (B) Analysis of GSH fluorescent intensity data. All experiments were performed in at least three replications, and the data statistics were represented by mean ± SEM. Values (a, b) with different superscripts in the columns are significantly different (p < 0.05).

Figure 4

Influences of MitoQ on the MMP level in matured bovine oocytes. (A) Representative images of MMP (red) staining of oocytes in control group and MitoQ treatment group. Scale bar: 200 µm. (B) Analysis of MMP fluorescent intensity data. All experiments were performed in at least three replications, and the data statistics were represented by mean ± SEM. Values (a, b) with different superscripts in the columns are significantly different (p < 0.05).

Figure 5

Influences of MitoQ on mitochondrial function in matured bovine oocytes. (A) Quantitative analysis of ATP content level. (B) Quantitative analysis of mt-DNA copies number level. All experiments were performed in at least three replications, and the data statistics were represented by mean ± SEM. Values (a, b) with different superscripts in the columns are significantly different (p < 0.05).

Figure 6

Influences of MitoQ on antioxidant-related and mitochondria-related genes in matured bovine oocytes. qPCR quantitative analysis of mRNA expression of apoptosis-related genes (BAX, BCL2), antioxidant-related genes (CAT, SOD), and mitochondria-related genes (DNM1, MFN2). All experiments were performed in three replications, and the data statistics were represented by mean ± SEM. Values (a, b) with different superscripts in the columns are significantly different (p < 0.05).