Etossulfato de fenazina na maturação in vitro de oócitos bovinos

Abstract

The objective was to evaluate different doses of phenazine ethosulfate (PES) during in vitro maturation of bovine oocytes and their consequences until thawing in vitrified embryos. The concentrations 0; 0.16; 0.4 and 1.0 µM were evaluated on embryo production, hatching and expansion rates, lipid content and morphological characteristics. Refrigerator oocytes (n = 2,232) were matured for 24 hours, part was subjected to fluorescence analysis, the others were cultured to D7, of which the grade I embryos were vitrified, then heated and cultured for 48 hours. A minimum of 550 CCOs per treatment were matured in 13 replicates resulting in 400 vitrified embryos. Data were analyzed by SAS® statistical package. The rate of embryos produced for the Control (C = 41.5 ± 1.8, n = 237) was higher (P <0.01) compared to PES0.16 (32.5 ± 1.7, n = 182). ) and PES1 (32.6 ± 1.7, n = 186), but did not differ from PES0.4 (35.6 ± 1.7% n = 210). The treated groups did not differ from each other. The hatching rate (P = 0.10) tended to be higher for PES1 (34.3 ± 5.6, n = 32) and PES0.4 (32.4 ± 5.6, n = 38) in Control (27.2 ± 5.7, n = 13) and PES0.16 (22.4 ± 5.8, n = 17). The expansion rate after 48 hours of cultivation was the same (P <0.05) for the Control (27.1 ± 5.2, n = 20), PES0.16 (24.3 ± 5.6, n = 20) and PES1 (10.3 ± 2.0, n = 12). The groups PES0,4 (17,7 ± 3,5, n = 10) and PES1 did not differ from each other. Higher proportion of PES1 oocytes (P <0.01) reached advanced meiosis stages (> 90%) than Control (50%). There was no treatment effect on the amount of apoptotic cells or MCI. In D9 there was an increase in apoptotic cells (P <0.01) and a reduction in the number of total cells (P <0.01) and MCI (P <0.01) in blastocysts. Lipid concentration (triglycerides, phospholipids and cholesterol) in oocytes was lower (P <0.01) in treated groups compared to Control. PES1 and PES0.4 triglycerides did not differ from Control during cultivation; in PES0.16 were higher (P = 0.01) than Control. The phospholipid and cholesterol concentrations of PES0.4 and PES0.16 were higher (P <0.01) than in Control and PES1. Blastocysts that survived and hatched 48 hours after thawing were 77% of PES0.4, 72% of PES1, versus 44% of PES0.16 and 25% of Control indicating a positive treatment effect. Lipid concentration was decreased by PES in oocytes, but apparently there was a compensatory effect in the culture phase, so PES used only during IVM may lead to lipid increase in embryos.