AUTHOR=Zhu Zhendong , Zhang Weijing , Li Rongnan , Zeng Wenxian 

TITLE=Reducing the Glucose Level in Pre-treatment Solution Improves Post-thaw Boar Sperm Quality

JOURNAL=Frontiers in Veterinary Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.856536

DOI=10.3389/fvets.2022.856536

ISSN=2297-1769

ABSTRACT=Frozen-thawed boar sperm was not widely used in pig artificial insemination as the sperm quality damaged by biochemical and physical modifications during the cryopreservation process. The aim of this study was to investigate whether reduction of the glucose level in diluted medium could protect the post-thaw boar sperm or not. Boar sperm was diluted with the medium with different doses of glucose (153, 122.4, 91.8, 61.2, 30.6 and 0 mM) during the cooling process. The sperm motility patterns and glycolysis were evaluated during cooling process, meanwhile the post-thaw sperm quality, ATP level, mitochondrial function as well as the apoptosis were also measured. It was observed that 153 mM glucose treatment showed the highest glycolysis in boar sperm as the activities of hexokinase, fructose-bisphosphate aldolase A (ALDOA) and lactate dehydrogenase (LDH) is the highest as well as the lactate level, and reduction of the glucose level from 153 mM to 30.6 mM suppressed the sperm glycolysis. In addition, 153 mM glucose treatment made sperm with circle-like movement along with high value of curvilinear velocity (VCL) and amplitude of the lateral head (ALH), while decreasing the glucose level reduced those patterns in the cooling process. Moreover, reduction of the glucose level also significantly increased the post-thaw sperm total motility, progressive motility, straight-linear velocity (VSL), membrane integrity and acrosome integrity, and the 30.6 mM glucose treatment showed the highest value among the treatments. Furthermore, post-thaw sperm succinate dehydrogenase (SDH) activity, malate dehydrogenase (MDH) activity, mitochondrial membrane potential as well as ATP level were increased by reducing the glucose level from the 153 mM to 30.6 mM. Interestingly, the 30.6 mM glucose treatment showed the lowest apoptosis of post-thaw sperm among the treatments. Those observations suggest that reduction of the glucose level in diluted medium increased the post-thaw boar sperm quality via decreasing the glycolytic metabolism. These findings provide novel insights that reduction of boar sperm activity via decreasing sperm glycolysis during the cooling process helps to improve the post-thaw sperm quality during cryopreservation.