Effects Of Metformin On Boar Sperm At Room Temperature Storage And Its Mechanism

The method of liquid storage of semen at room temperature for a certain time in vitro greatly promotes the popularization and utilization of artificial insemination technology.However,the integrity of sperm structure(such as the integrity of plasma membrane and acrosome)is undermined by adverse effect of various physical and chemical factors during storage,which contributes to the disorder of cellular energy metabolism system of sperm as well as motility and fertility decline.Therefore,it is necessary to investigate agents that can maintain the quality of semen.Metformin,as a therapeutic drug for type 2 diabetes,can improve metabolic flexibility and increase capability of cellular glucose uptake,but the effects of metformin on boar sperm are not well-defined.This study investigates the effects of metformin on boar spermatozoa quality at room temperature(17~?)and verifies whether metformin affects the energy metabolism of sperm by the possible role of AMP-activated kinase(AMPK)in vitro.We estimate sperm motility parameters,membrane integrity,acrosome integrity,mitochondrial membrane potential,cellular ATP content,glucose uptake,lactate excretion and activity of lactate dehydrogenase to clarify the effects of metformin on boar sperm in vitro.The results are showed below:Metformin improved the boar spermatozoa quality at 17~?.Different concentrations of metformin were added to the semen extender and we found that sample added with metformin(200?mol/L)displayed significantly higher sperm motility,plasma membrane integrity,mitochondrial membrane potential,cellular ATP content than control(P<0.05).Metformin improved sperm quality and energy metabolism by activating AMPK.Phosphorylation AMPK localized to the equatorial segment and whole sperm tail.Metformin promoted AMPK phosphorylation of Thr-172 in 17~? and 37~?(P<0.05)as well as glucose uptake and metabolism(Glycolysis)in boar sperm(P<0.05).AMPK inhibitor(Compound C)decreased boar sperm AMPK phosphorylation and when treated with Compound C,metformin could not improve sperm motility,membrane integrity and glucose uptake as well as maintain mitochondrial membrane potential,cellular ATP content,lactate excretion and lactate dehydrogenase(P>0.05).In conclusion,metformin is able to facilitate the glucose uptake as well as glucose metabolism(glycolysis)of boar spermatozoa and maintain sperm motility and structure integrity in vitro.Meantime,metformin could improve sperm quality and alleviate the time-dependent deterioration of boar spermatozoa when storage in 17~?.