Restoring ovarian antioxidant balance to combat female reproductive aging

To determine the effects of antioxidant treatment on reproductive function in a mouse model of advanced maternal age. Female outbred CF-1 mice were naturally aged for 9 months prior to an 8-week antioxidant regimen of 45 mg daily acai berry pulp (total polyphenol content of 6,618 mg Gallic acid equivalent/100 g). Control aged mice (11 months) and young mice (8-12 weeks) received the same standard diet without acai. Superovulated mice from each group underwent uterine flushing for in vivo-developed blastocysts on D4 of pregnancy. Expanded blastocysts were transferred into pseudopregnant aged mice with implantation rates determined on D8. Oocytes were collected for enzyme analysis (n=4 per group), and serum ferric-reducing antioxidant power (FRAP) was measured (n=9 aged, 10 acai-treated aged). Continuous data were compared using the Kruskal-Wallis test with Dunn’s multiple comparisons when overall P < 0.05. Categorical data were analyzed using Fisher’s exact test with Koopman asymptotic score to determine relative risk (RR). Of the aged mice that plugged after breeding, only 52.9% had in vivo-developed D4 embryos, compared to 100% of young mice (P < 0.01) and 83.3% of acai-treated aged mice (P < 0.05). D4 embryos from aged mice were of poorer quality with less expanded blastocysts than young (1.3 ± 0.4 vs. 17.2 ± 3.5; P < 0.0001) or acai-treated aged mice (4.5 ± 1.4; P < 0.05). Embryos from aged donors were less likely to implant in recipient aged mice compared to embryos from young (42.9 vs. 89.3%; RR 2.08; P < 0.01) or acai-treated aged donors (76.5%; RR 1.78; P = 0.075). Less oocytes were retrieved from aged and acai-treated aged mice compared to young mice (P < 0.05), but the two aged groups were not different (P > 0.99). Thus, the estimated rate of blastocyst formation per oocyte ovulated was higher in acai-treated vs. control aged mice (51.8 vs. 17.4%, respectively). Compared to young oocytes, aged oocyte enzyme expression of the E3 ubiquitin ligase Parkin (PRKN) was reduced (1.1 ± 0.9 vs. 0.2 ± 0.04), but acai-treated oocyte PRKN was not reduced (1.4 ± 1.0). Phosphorylated PRKN was elevated in aged oocytes (1.2 ± 0.5 vs. 2.0 ± 0.5) but not in acai-treated oocytes (1.1 ± 0.2); these data did not reach significance (overall P = 0.37 and 0.38, respectively). Antioxidant power trended higher in serum from acai-treated aged mice compared to aged mice (4.0 ± 0.6 vs. 2.9 ± 0.1; P = 0.094). Antioxidant supplementation in aged mice was sufficient to counteract the typical aging-related reduction in oocyte quality, as evidenced by increased blastocyst development and quality, as well as improved embryo implantation potential. The molecular basis for these improved outcomes could involve restoration of redox balance, ovarian mitochondrial activity, and/or endoplasmic reticulum function. Ongoing studies will look at ovarian cell-type specific effects of systemic antioxidant treatment.