Cold storage of sperm of rainbow trout (oncorhynchus mykiss): Effect on motility, intracellular superoxide, plasma membrane integrity and mitochondrial membrane potential

Abstract

In teleostei, as opposed to what happens in mammals, most of the studies that evaluate the quality storages of semen are oriented toward the exposure of spermatozoa to some reactive oxygen species (ROS), the utilization of antioxidants in the diet, or the incorporation of these in seminal plasma. There is no available the literature covering the presence of superoxide ions (O₂^._), or the function of these on the interior of the spermatozoa that have been stored. In this study, we evaluated the effect of storage on intracellular O₂^._, motility, plasmatic membrane integrity, and mitochondrial membrane potential (ΔΨ^Mit) of spermatozoa of rainbow trout (oncorhynchus mykiss). Semen was extracted and put into storage for 12 days at 4 ºC. Spermatozoa motility, (ΔΨ^Mit), plasmatic membrane integrity were evaluated every 4 days, and intracellular O₂^._ was detected. It was found that 82.59% of the cells were positive for the staining of O₂^._ on the day of sample extraction, while sperm motility, ΔΨ^Mit and plasmatic membrane integrity only showed deterioration after the eighth day of storage. Only ΔΨ^Mit is correlated negatively with O₂^._ starting from the eighth day of storage (r = -0.56 P < 0.05). Regarding motility and plasmatic membrane integrity, these were not affected by intracellular O₂^._, although the deterioration observed in these last two indicators, could have been caused by the prolonged contact of the spermatozoa with contaminating agents that were not evaluated in this study.