Investigation Of Sperm Glucose Metabolism During Lliquid Storage Pig Semen

Liquid semen storage is of great importance for the application of pig artificial insemination. The technique for liquid storage of pig semen is hindered, however, by problems such as complicated extender composition, limited duration and unstable outcome. Although it is accepted that energy supply and prevention of oxidative stress are the two major issues for extended liquid semen storage, research are few on sperm glucose metabolism under such conditions. Furthermore, the existence of the ppp pathway and need for the Krebs cycle in sperm of different species has yet to be confirmed. Studies on sperm glucose metabolism during liquid storage of pig semen are thus important not only for understanding sperm energy metabolism but also for improving the technique of liquid semen storage. The objective of this project is to study sperm glucose metabolism during liquid semen storage. To this end, boar semen will be preserved at different temperatures in the basic PBS extender that does not contain any energy substrates but supplemented with glucose, intermediate metabolism of glucose and/or inhibition of glucolysis, PPP or mitochondria electron transport. At different times of preservation, sperm motility, viability and other parameters will be evaluated. Data obtained will also be used to formulate an optimal system that provided the best energy for extended liquid storage of boar semen.The result of this study indicate that:1) Motility and viability of boar sperm were the highest, compared to5℃and25℃, when semen was stored at15℃, and an over30%of sperm motility was maintained for4days. We have established an efficient semen storage system, which is simple and chemically defined, for sugar metabolism research.2) Motility and viability of boar sperm were decreased when the semen was diluted by PBS supplied with Ca2+and Mg2+at15℃.3) Motility and viability of boar sperm were high when semen was diluted by PBS supplied with3mM glucose storaged at15℃, and an over30%of sperm motility was maintained for5days.4) Motility and viability of boar sperm were high when semen was diluted by PBS supplied with5mM sodium pyruvate stored at15℃, and an over30%of sperm motility was maintained for5days.5) Motility of boar sperm extendered in PBS containing3mM glucose supplied with iodoacetae, inhibitor of glycolysis, was lower significantly than the control group which was without iodoacetate, in the meanwhile the time of boar sperm motility of exceeding30%maintained was declined significantly.6) Motility of boar sperm extendered in PBS containing3mM glucose supplied with6-AN, inhibitor of pentose phosphate pathway, was lower significantly than the control group which was without6-AN, in the meanwhile the time of boar sperm motility of exceeding30%maintained was declined significantly.7) Motility of boar sperm extendered in PBS containing3mM glucose supplied with rotenone, inhibitor of pentose phosphate pathway, was lower significantly than the control group which didn’t contain rotenone. Meanwhile the time of boar sperm motility of exceeding30%maintained was declined significantly.In conclusions:1) It is favourable for sperm survival when the semen is stored at15℃, compared to5℃and25℃.2) It is unfavourable for sperm’s survival when the extender is supplementted with Ca2+and Mg2+during liquid storage.3) Motility and viability of boar sperm were higher significantly when the semen was stored in PBS supplied with3mM glucose at15℃. However, the motlity and viability of boar sperm were decreased when the concentration of glucose exceeding3mM.4) Pyruvate could be utilized by boar sperm except glucose.5) It seem that boar sperm metabolizes glucose to maintain motility not by pentose phosphate pathway but by aerobic glycolysis and oxidative phosphorylation pathways during liquid storaged at15℃.