Glycolysis Produces the Power for Sperm Motility

Researchers studying male infertility have found that the enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPD), a key component of the glycolysis pathway, is required to produce the energy needed by sperm cells to migrate towards the awaiting eggs.

Investigators at the University of North Carolina Medical School (Chapel Hill, NC, USA) genetically engineered a line of mice lacking the gene for GAPDS, the form of the enzyme found in mouse sperm cells. They reported in the November 16, 2004, online edition of the Proceedings of the [U.S.] National Academy of Sciences that while these animals mated normally with receptive female mice, they were infertile. Examination of their sperm under the microscope revealed that the sperm showed only a slight side-to-side movement, but were incapable of moving forward.

At the biochemical level it was found that although mitochondrial oxygen consumption was unchanged, sperm from these mice had adenosine triphosphate (ATP) levels that were only 10.4% of those in sperm from control mice. Thus, most of the energy required for sperm motility was generated by glycolysis rather than oxidative phosphorylation.

"We were very surprised at this finding,” said senior author Dr. Deborah O'Brien, associate professor of cell and developmental biology at the University of North Carolina School of Medicine. "It turned out that almost all of the sperm's motility and ATP production depended on this enzyme.”

Since a form of GAPD is present in human sperm, the authors suggested that it might be a good target for contraceptive agents, and that environmental agents that affect its activity may be related to male infertility in humans.




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