Aqueous cigarette smoke extract reduces mitochondrial potential and increases nuclear degeneration in bovine oocytes...

This study investigated the cytotoxicity of different concentrations of aqueous extract of cigarette smoke (AECS) during in vitro maturation (IVM) of bovine oocytes, evaluating the potential synergy among its various compounds, including nicotine. The AECS was evaluated by liquid chromatography to identify nicotine amount and by atomic force microscopy (AFM) to analyze the morphology of particles. To IVM, bovine ovaries (n = 30) were collected in local slaughterhouse and submitted to slicing. Only oocytes that exhibited homogeneous cytoplasm, diameter higher than 110 µm, and surrounded by, at least, two layers of compact cumulus cells were selected. Cumulus-oocyte complex (COCs) were matured in groups under mineral oil in TCM-199 + alone (CTRL) or TCM-199 + supplemented with 1, 2.5 or 5 % of AECS, at 38,5°C in a humidified atmosphere containing 5 % CO2 in air for 24 h. After IVM period, oocytes were denuded and evaluated to chromatin configuration by Hoechst, and ROS and mitochondrial potential by H2DCFDA and JC-1, respectively. The data distribution was assessed using the Shapiro-Wilk test for homogeneity and ANOVA One-way with post hoc of Tukey considering P < 0.05. The results revelated high nicotine levels (158.40 µg/mL) in the AECS and nanoparticles with 14,66 ± 4,08 nm of diameter. Regardless of AECS concentration used, high chromatin degenerated rates of oocytes after IVM, and an increase of ROS levels and a reduction of mitochondrial (P < 0,05) was observed. Thus, it can be concluded that AECS exhibits significant cytotoxic properties towards bovine oocytes, particularly due to the presence of elevated concentrations of nicotine.