The effect of Unithiol on the viability of Sus scrofa domesticus oocytes in an in vitro culture system

Oxidative stress during in vitro maturation of porcine oocytes is one of the factors that reduce viability and exit of competent to insemination female gametes. Exogenous antioxidants, which includes unithiol, reduce production of active oxygen forms in cells. In the present study, pig’s cumulus-oocyte complexes (COC) were cultivated for 44h with and without single-agent at concentrations of 0,42 mg/ml and 0,84 mg/ml. After 22 h was found an increasing (by 21%, p<0,01) of the proportion of COC reinitiated meiosis in oocyte groups cultivated with 0,42 or 0,84 mg/ml of unithiol in comparison with control. After 44h all gametes in experimental groups reinitiated meiosis (85, 83 and 90%). After 44 h, in oocyte group cultivated with 0,42 mg/ ml of unithiol there was a decreasing (by 28%) in proportion of mature cells (p><0,001), and introduction of 0,84 mg/ml of unithiol into environment resulted in a decrease of 31% (p 0,001) in level of cells having completed meiosis compared to control. After 22 h of cultivation, proportion of degenerated cells in a group cultivated with 0,42 mg/ml of unithiol was above control by 14% (p><0,05), and with a concentration of 0,84 mg/ml - by 34% (p><0,001). After 44 h of cultivation, unithiol in concentrations of 0,42 and 0,84 mg/ml continued to initiate degenerative changes in oocytes. Proportion of cells with degeneration was 25 and 32% higher compared to control, p><0,01). Introduction of unithiol in concentrations of 0,84 and 0,42 mg/ml into cultural media caused a decreasing percentage of mature oocytes and increasing level of female gametes with degenerated chromatin. Observed effects of unithiol in studied dosages on meiotic maturation of pig’s in vitro donor oocytes do not allow to recommend it as an exogenous antioxidant for reducing oxidative stress in pig oocytes under in vitro maturation. > < 0,01) of the proportion of COC reinitiated meiosis in oocyte groups cultivated with 0,42 or 0,84 mg/ml of unithiol in comparison with control. After 44h all gametes in experimental groups reinitiated meiosis (85, 83 and 90%). After 44 h, in oocyte group cultivated with 0,42 mg/ ml of unithiol there was a decreasing (by 28%) in proportion of mature cells (p < 0,001), and introduction of 0,84 mg/ml of unithiol into environment resulted in a decrease of 31% (p 0,001) in level of cells having completed meiosis compared to control. After 22 h of cultivation, proportion of degenerated cells in a group cultivated with 0,42 mg/ml of unithiol was above control by 14% (p < 0,05), and with a concentration of 0,84 mg/ml - by 34% (p < 0,001). After 44 h of cultivation, unithiol in concentrations of 0,42 and 0,84 mg/ml continued to initiate degenerative changes in oocytes. Proportion of cells with degeneration was 25 and 32% higher compared to control, p < 0,01). Introduction of unithiol in concentrations of 0,84 and 0,42 mg/ml into cultural media caused a decreasing percentage of mature oocytes and increasing level of female gametes with degenerated chromatin. Observed effects of unithiol in studied dosages on meiotic maturation of pig’s in vitro donor oocytes do not allow to recommend it as an exogenous antioxidant for reducing oxidative stress in pig oocytes under in vitro maturation.

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