Male Contraceptive for Mice: Humans Next?

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Hey ladies, in the future you might be able to toss out your birth-control pills and hand over the daily responsibility to the guys.

Male mice lacking a certain protein — one that has a human counterpart — had reduced fertility, a new study found.

Sperm malfunction

The research team, led by Yildiz Yildiz of the University of Texas Southwestern Medical Center, generated mice lacking the GBA2 protein, called knockout mice.

They collected sperm from mice with and without the GBA2 protein and incubated the sperm with unfertilized eggs. Large bundles of sperm from normal mice bounded to the eggs, while the knockout sperm did not.

About 30 percent of the eggs fertilized by normal sperm developed into blastocysts, embryos that haven’t yet implanted to the uterus lining. The knockout sperm didn’t result in any blastocysts.

Looking under a microscope, the researchers found the sperm of knockout mice had abnormally large, round heads, were fewer in number and moved more slowly than sperm from normal mice.

Male pill

Prior to this study, scientists assumed the GBA2 protein worked like another protein in the same family called GBA1, which breaks down bile acid. “From what we could tell, the enzyme does little or nothing in bile acid metabolism,” said research team member David Russell, also of the University of Texas Southwestern Medical Center.

Humans lacking GBA1 develop symptoms of Gaucher’s disease — enlarged internal organs and neurological defects. One treatment for the disease has rendered many male patients infertile, an effect scientists assumed was linked to GBA1. But the new findings suggest the treatment is actually inhibiting the GBA2 protein.

Since the two proteins work individually, the scientists suggest a disruption of GBA2 could lead to a male contraceptive that would have no effect on bile acid metabolism. “If you could make a very selective inhibitor of GBA2 then you would cause the malformed sperm, you would render that individual infertile,” Russell told LiveScience.

Jeanna Bryner
Managing editor, Scientific American

Jeanna Bryner is managing editor of Scientific American. Previously she was editor in chief of Live Science and, prior to that, an editor at Scholastic's Science World magazine. Bryner has an English degree from Salisbury University, a master's degree in biogeochemistry and environmental sciences from the University of Maryland and a graduate science journalism degree from New York University. She has worked as a biologist in Florida, where she monitored wetlands and did field surveys for endangered species, including the gorgeous Florida Scrub Jay. She also received an ocean sciences journalism fellowship from the Woods Hole Oceanographic Institution. She is a firm believer that science is for everyone and that just about everything can be viewed through the lens of science.