The effect of metformin on murine and bovine sperm motility parameters

Sperm motility is one of the most relevant parameters related to the fertilizing capability of the spermatozoa. Understanding the anatomy and physiology of sperm flagellum allows for the use of diverse molecules for improving sperm motility, such as metformin. Metformin is a molecule known to stimulate the capability of the cell to uptake and metabolize its energy substrate, acting as an activator of AMP kinase. Its activation leads to the phosphorylation of several substrates implicated in the hyperactivation of the flagellum, as a previous step for the appropriate fertility of the spermatozoa. This paper presents the results of experiments testing the effect of metformin in bull and murine spermatozoa, and reviews aspects related to the use of energy substrate by the spermatozoa, and the molecular mechanisms implicated in metformin role on sperm motility. Since semen analysis is always performed in Eppendorf tubes, whereas the capacitation of sperm cells for in vitro fertilization is performed in drops, we evaluated if there were differences in CASA parameters between sperm cells evaluated in Eppendorf tubes versus drops.