Adenosine Triphosphate Production by Bovine Spermatozoa and Its Relationship to Semen Fertilizing Ability

Abstract

This article's objectives are to investigate the relationship between adenosine triphosphate (ATP) production (oxidative phosphorylation and glycolysis) and fertility of bovine spermatozoa, determine the proportion of oxygen consumption devoted to proton leak and that due to nonmitochondrial processes, and discover whether freeze/thawing affects sperm oxygen consumption. Oxygen consumption of bovine spermatozoa was measured using a standard Clark electrode and, for the first time, in an Oxygen Biosensor System (OBS). Total ATP formation by bovine spermatozoa was calculated from the oxygen consumption and lactate production (glycolysis) by the same spermatozoa sample. ATP production varied from 1.99 to 8.09 mmol ATP per 10 8 spermatozoa per hour; glycolysis accounted for 16% to 38% of ATP. Nonmitochondrial oxygen consumption could not be detected in bovine spermatozoa using these methods. A significant proportion (16%-43%) of oxygen consumption was insensitive to oligomycin and was due to ''proton leak.'' There was no significant difference between oxygen consumption of frozen/thawed and fresh spermatozoa for 2 of the 3 bulls tested. However, oxygen consumption of frozen/thawed spermatozoa was significantly higher (P , .05) than fresh spermatozoa for the third bull. When ZO 2 of frozen/thawed spermatozoa from 20 bulls was compared with their 49 day nonreturn rates (NRRs), oxygen consumption was correlated positively with NRR (ie, fresh spermatozoa with a higher ZO 2 were more fertile). Moreover, total ATP production correlated with NNR better than ZO 2 . Bulls with a lower NRR produce spermatozoa that are susceptible to damage during the freeze/thawing process, causing an increase in ZO 2 , possibly due to mitochondrial membrane damage resulting in more energy being expended in maintaining the proton gradient, or capacitation-like changes causing hyperactivation. Oxygen consumption measured in the OBS may be useful in assessing bovine sperm fertility.Key words: Fertility, semen analysis, sperm, oxygen consumption. J Androl 2008;29:449-458A rtificial insemination (AI) accounts for approximately 80% of breedings in the United Kingdom dairy herd. However, the efficiency of AI is highly variable, with an average of 1.7 doses of semen being required per cow to establish a pregnancy. There is a continuing need for more reliable markers of sperm fertilizing ability. A simple, relatively inexpensive method that correlates with nonreturn rate (NRR; sperm fertility measured by the percentage of cows that do not require reinsemination) could reduce the number of low-fertility bulls that enter the costly proofing program of a stud. These could then be replaced with bulls of higher fertility. The test could also be used routinely to assess the fertility of semen before and/or after it is processed for AI. Current methods to evaluate semen quality include tests of motility, morphology, membrane integrity and membrane strength (osmotic resistance test), chromatin structure, and gamete interactions (Rodriguez-Martinez,...

Effects of Some Respiratory and Glycolytic Inhibitors on Mitochondrial Functionality in Bovine Semen

“…Uprating of m in motile sperm of 3/4 bulls was seen in post-thaw semen. This was consistent with the results of Garrett et al, [21] who observed higher oxygen consumption rate in post-thaw semen. Whereas, semen washed in Ruthin medium: m has been increased with increase in incubation time in all bulls of fresh sperm and 2/6 bulls of post-thaw sperm respectively.…”

Evidence for Compromised Metabolic Function and Limited Glucose Uptake in Spermatozoa from the Teratospermic Domestic Cat (Felis catus) and Cheetah (Acinonyx jubatus)1

“…Examination of stoichiometric ratios revealed that 60%-70% of produced lactate could have been explained on the basis of pyruvate uptake and reduction (in contrast to only 0%-40% generated from exogenous glucose catabolism). These are important observations given that lactate production (measured by enzyme-linked fluorescence) has been used as an indicator of glycolytic metabolism for other species [25,30,31]. Ongoing research in our laboratory supports this mechanism of lactate production in felid spermatozoa.…”

“…It is known that spermatozoa are capable of generating energy in the form of ATP through glycolysis and/or oxidative phosphorylation. However, the relative importance of each pathway to sperm functions, such as motility and capacitation, varies among species [18][19][20][21][22][23][24][25]. Oxidative phosphorylation is 18 times more efficient than anaerobic glycolysis and provides a significant proportion of the ATP supply in spermatozoa of most species [21].…”

Evidence for Rapid Oxidative Phosphorylation and Lactate Fermentation in Motile Human Sperm by Hyperpolarized 13C Magnetic Resonance Spectroscopy

“…Pyruvate Dehydrogenase; PDH) 5 . The generation of adenosine triphosphate (ATP) is essential for sperm motility 11 and the two main energy pathways are: (a) glycolysis within the cytosol; and (b) Oxidative Phosphorylation (OxPhos) by the mitochondria. There have been numerous studies in the literature examining the relative importance of glycolysis and OxPhos (reviewed by du Plessis 4 and Ferramosca) 12 .…”