Rosiglitazone in the thawing medium improves mitochondrial function in stallion spermatozoa through Akt phosphorylation and reduction of caspase 3

ABSTRACT Background The population of stallion spermatozoa surviving thawing, experience, among other changes, compromised mitochondrial functionality and accelerated senescence. It is known that the stallion spermatozoa show very active oxidative phosphorylation that may accelerate sperm senescence through increased production of reactive oxygen species. Rosiglitazone has proven to enhance the glycolytic capability of stallion spermatozoa maintained in refrigeration. Objectives Thus, we hypothesized that thawed sperm may also benefit from rosiglitazone supplementation. Material and Methods Thawed sperm doses were washed and re-suspended in Tyrodes media, split sampled and supplemented with 0 or 75 μM rosiglitazone. After 1 and two hours of incubation, mitochondrial functionality, Akt phosphorylation and caspase 3 activity were evaluated. Further samples were incubated in presence of the Akt1/2 inhibitor, compound C (AMPK inhibitor) and GW9662 (antagonist of the PPARγ receptor). Results Rosiglitazone maintained Akt phosphorylated and reduced caspase 3 activation (p<0.01) that was prevented by incubation in presence of the three inhibitors. Rosiglitazone also enhanced mitochondrial functionality (p<0.01). Conclusion We provide, for the first time, evidences that the functionality of frozen stallion spermatozoa can be potentially improved after thawing through the activation pro survival pathways, opening new clues to improve current sperm biotechnologies.