Metformin improves fish sperm quality by regulating glucose uptake capacity during in vitro storage.

Generally, what matters most to fish sperm is a good storage condition in vitro that can both ensure its high motility after fresh water activation and avoid the damage of the nonactivated state. An appropriate additive can provide suitable storage conditions for sperm. Therefore, a suitable additive of fish sperm is necessary for fish to promote effective artificial reproduction. In this study, we evaluated the effects of different concentrations of metformin (Met) on fish sperm under storage in vitro. Compared with the control group, Met was more effective at improving the quality and fertilization capacity of fish by increasing the adenosine triphosphate (ATP) content within the sperm. Further study found that Met stabilized the ATP level by enhancing the glucose uptake in fish sperm, and this effect might be associated with the activation of AMP-activated protein kinase (AMPK) in sperm. The beneficial effects of Met on fish sperm suggest that Met may hold great promise for the practice of storing fish in future vitro storage.