The potential protective effect of reduced glutathione (GSH) and trolox (TRX), an analogue of vitamin E, supplementation during in vitro culture (2h, 39°C) of electroejaculated frozen/thawed red deer sperm was investigated. Cryopreserved sperm were thawed and incubated with no additive (Control) and 1mM or 5mM of each antioxidant to find out whether these supplementations can maintain the sperm quality, considering the use of thawed samples for in vitro techniques such as in vitro fertilisation (IVF), sperm sex sorting or refreezing. The effect of GSH on sperm motility was positive compared to TRX which was negative (P<0.001). After 2h of incubation at 39°C, use of GSH improved motility while TRX supplementation reduced sperm motility compared with Control samples without antioxidant. Use of TRX at both concentrations (1 and 5mM; TRX1 and TRX5) resulted in lesser percentages of apoptotic sperm (12.4±1.1% and 11.7±0.9%) than GSH1, GSH5 (15.2±1% and 14.6±1.1%) and Control samples (16.9±1.2%) (P<0.001). Use of GSH at both concentrations (1 and 5mM) resulted in greater mitochondrial activity as compared with findings for the Control, TRX1 and TRX5 groups. Results of this study indicate that GSH is a suitable supplement for electroejaculated red deer sperm. It would be necessary to conduct fertility trials (in vivo and in vitro), to assess whether GSH supplementation of thawed red deer sperm could improve fertility rates.
Keywords: Antioxidant; Cryopreservation; Red deer; Reduced glutathione; Sperm; Trolox.
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