14 DAY TRIAL // Researchers at University of Texas Southwestern Medical Center have identified in mice a protein, which has a human counterpart, and - if missing - renders the males sterile. The finding could lead to the development of an oral male non-hormonal contraceptive pill, unlike female contraceptive pills which are hormonal.
Individuals lacking the protein, named GBA2, were called knockout mice. Scientists collected sperm from healthy and from knockout mice and put in contact with unfertilized eggs. A large number of sperm cells from healthy mice attached to the eggs, while the knockout sperm did not.
About 30 % of the eggs fertilized by normal sperm passed into blastocysts, starting embryonic development. The knockout sperm didn't lead to any blastocysts. At a microscopical view, the scientists discovered that sperm cells of the knockout mice had abnormally large, round heads, and were less and slower than normal sperm cells.
Previously, scientists supposed that GBA2 functioned similarly to another protein in the same group 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.
In humans, the lack of GBA1 develops Gaucher's disease: enlarged internal organs and neurological defects. One of the treatments for Gaucher's disease has rendered many male patients infertile, an effect now linked to inhibiting GBA2 and not especially due to GBA1. As the two proteins work separately, this would mean that targeting GBA2 could 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.