Ação da miricetina na maturação in vitro de oócitos bovinos

Abstract

In the in vitro embryo production systems (PIVE), culture maturation (IVM) is one of the limiting steps, specially due to the action of EROs produced in the system. Myricetin is one of the natural flavonoids, known for its antioxidant potential, which may improve the PIVE, being supplemented in the medium of IVM. In order to test the effects of myricetin on bovine IVM, oocytes were matured for 24 h in the presence (1, 5 and 10 μM) or in the absence (control group) of myricetin. The oocytes were stained with Hoechst and visualized under a fluorescence microscope for nuclear evaluation. The percentage of nuclear maturation did not differ between the control group (64.5%), and treatments 1 μM (66.9%) and 5 μM (70.8%), but treatment with 10 μM (42.7%) was damaging for oocytes. Regarding the evaluation of the embryonic development, the oocytes were fertilized and cultured in vitro, being the embryonic development rates determined after 7 days of culture. In the embryo production phase, only myricetin 1 μM was used. Relative to embryonic development rates, there was not difference (P > 0.05) between control group (47.2%) and treatment 1 μM (33.3%). The embryos were stained by the TUNEL technique, in order to evaluate cell apoptosis signs, revealing that the myricetin 1 μM treatment resulted in a lower rate of apoptotic blastomers (27%) when compared to the control group (41.2%) (P < 0.05). It was concluded that the IVM supplementation with 10 μM myricetin interferes in oocyte maturation rate, however, 1 μM myricetin does not interfere in the rate of blastocyst production and decreases the number of apoptotic blastomers.