American researchers may have found an effective and hormone-free birth control pill for men. A study in the journal Cell shows that a small molecule makes male mice reversibly infertile without putting a damper on their sex drive. When the animals stop taking this new form of birth control, their sperm rebound and they are again able to sire perfectly healthy offspring.
"This compound produces a rapid and reversible decrease in sperm count and motility with profound effects on fertility," said lead author James Bradner of the Dana-Farber Cancer Institute.
A male birth control pill hasn't been easy to come by in large part because of the challenge of getting any drug across the blood:testis barrier, where it can reach the sperm-generating cells. Known as JQ1, the compound targets a testis-specific protein called BRDT that is essential for fertility. When mice are given the BRDT-inhibiting molecule, they begin producing fewer sperm and those sperm they do produce don't swim as well.
There are no apparent adverse effects on the males' future offspring. "We envision that our discoveries can be completely translated to men, providing a novel and efficacious strategy for a male contraceptive," the researchers wrote.
However, not everyone is convinced. “They’ve found a nice system for studying spermatogenesis, but it would be a stretch to say that there’s a human application in the near future,” Mark Gill, of the Novartis Research Foundation in Switzerland, told Nature. He points out that there could have been developmental abnormalities unnoticed by the researchers or problems which develop later in life. Drug companies have stopped working on male contraceptives because it is too risky.