Mirtilo (Vaccinium ashei reade) melhora o dano ovariano induzido pela exposição sub-crônica ao cádmio em camundongos

Abstract

Cadmium is one of the most toxic pollutants which is widely distributed in the environment. Non-occupational human exposure to cadmium predominantly results from cigarette smoke, air pollution and consumption of cadmium contaminated foods and water. This metal presents a low rate of excretion from the body and a long biological half-life and for this reason cadmium accumulates over time in blood, kidney, and liver as well as in the reproductive organs, including the placenta, testis, and ovaries. Cadmium exposure is strongly associated with reproductive toxicity in both animal and human populations culminating in infertility and cancers in reproductive tissues. The pathogenesis of ovarian damage and reduction of follicle viability following cadmium exposure is generally ascribed to oxidative damage. Thus, antioxidant compounds could be an alternative therapy against cadmium toxicity. Emergent evidences suggest that eating more fruits and vegetables with antioxidant properties could help in preventing of several diseases. The blueberry (Vaccinium ashei Reade) fruit is one of the richest sources of antioxidant phytochemicals among fruits and vegetables. This way, we verified the in vitro antioxidant potential of the blueberry extract, which demonstrated a significant DPPH radical and reactive species (RS) scavenger activities. This extract showed high total polyphenol content (558.27 μg GAE/mL). After, this study evaluated the protective role of hydro-alcoholic extract of blueberry on the follicular viability and ovarian oxidative damage induced by sub-chronic cadmium exposure in mice. Mice received CdCl2 (2.5 mg / kg) subcutaneously and blueberry extract (2.5 mg/ kg) orally for 3 weeks (5 days weekly). Animals were euthanized after 24 hours the last administration, and ovaries were removed to determinate the glutathione peroxidase (GPx), glutathione-S-transferase (GST), δ-aminolevulinate dehydratase (δ-ALA-D) and 17 β-dehydrogenase hydroxysteroide (17β-HSD) enzymatic activities, RS levels, cadmium content and the follicles viability. The results demonstrated that animals cadmium-exposed presented a enhance of 2-folds on reactive species levels, reduction in δ-ALA-D and 17β-HSD activities (30 and 39% of reduction, respectively) as well as a decrease around 69% on follicular viability when compared with control group. No alteration was observed on ovarian GPx and GST activities. The therapy was effective in restoring RS levels, δ-ALA-D activity and partially improves the follicles viability altered by sub-chronic cadmium exposure. However, this therapy was not able to restore 17β-HSD activity, which suggest that the protective effect of blueberry is not related to hormonal activity. Thus, we verified that cadmium accumulates in mice ovary after sub-chronic exposure causing damage on this tissue and blueberry hydro-alcoholic extract presents antioxidant properties that could protect, at least in part, ovarian tissue from cadmium toxic effect.