The effect of antioxidants on sperm motility activation in the Booroolong frog

•Vitamin C and E were added to sperm samples and sperm motility activation assessed.•Vitamin C supplementation at all concentrations was detrimental to sperm motility.•Vitamin E supplementation had no effect on sperm motility.•Further investigation of the endogenous antioxidant system in anuran sperm is required.•Alternative antioxidants may be more suitable at improving sperm motility duration in vitro. Motile sperm can generate high levels of reactive oxygen species (ROS) post activation, and ROS can quickly accumulate to levels that impair motility and fertilising ability. The addition of antioxidants to sperm suspensions has been suggested as a means of reducing oxidative stress and enhancing sperm motility during and after sperm storage. Despite this, very few studies have attempted to experimentally test the effects of antioxidants on sperm motility activation in animals that use an external mode of fertilisation, espcially in amphibians. The present study aimed to investigate the effect of vitamin C and vitamin E on sperm motility activation in the Booroolong frog. Spermatozoa were activated in media containing either vitamin C (0, 0.05, 0.10, 0.15, 0.20, 0.25μgμL−1) or vitamin E (0, 0.25, 0.50, 0.75, 1.0, 1.25 1.50, 1.75μgμL−1). Sperm performance parameters (percent motility and velocity) were assessed using CASA at 0, 1, 2, 3, 4, 5 and 6h post-activation. Contrary to expectations, vitamin C supplementation was detrimental to sperm motility across all tested concentrations, while vitamin E had no effect. Further investigation on the endogenous antioxidant system of anuran sperm is required to ascertain whether alternative antioxidants may be more suitable at reducing ROS produced during sperm activation and improving sperm motility activation in vitro.