Oxidative stress and tumor necrosis factor-α-induced alterations in metaphase II mouse oocyte spindle structure

Objective(s): To examine the effect of exogenous exposure to hydrogen peroxide (H2O2) and tumor necrosis factor (TNF)-alpha on mouse metaphase II (MII) oocyte spindle structure and to examine the potential benefits of supplementing the culture media with vitamin C. Design: Prospective study. Setting: Research laboratory in a tertiary hospital. Intervention(S): None. Main Outcome Measure(s): Microtubule changes and alterations in chromosomal alignment. Result(s): Both concentration- and time-dependent alterations were seen in spindle structure after exposure to H2O2. An H2O2 concentration as low as 12.5 AM increased the odds of an oocyte with altered microtubule and chromosome alignment (score 3) by 93%. Significantly increased damage was seen with increasing period of incubation. Higher scores were seen after exposure to both TNF-alpha alone and in combination with H2O2 compared with controls. Changes in chromosomal alignment were comparable among the three groups. Oocytes coincubated with H2O, and vitamin C at 200 AM demonstrated less damage compared with those with H2O2 alone. Conclusion(s): Oxidative stress results in concentration and time-dependent alterations in the spindle structure and augments the effects induced by TNF-a. Proper oocyte handling in vitro may help reduce oxidative insult, thus improving the oocyte quality. Antioxidants may have a protective effect and need to be further evaluated