Reducing sperm’s swimming ability could be key to male contraceptive pill

Updated: Oct 07, 2012, 13:04 PM IST

Sydney: Australian researchers may have come closer to developing a male contraceptive pill.

They have discovered a way to cut off the fuel supply to the “motor” that drives human sperm, greatly reducing their swimming ability and opening a new avenue to developing a male pill.

The finding also throws new light on the little-understood reasons for infertility in men, the Sydney Morning Herald reported.

Led by Moira O’Bryan, of Monash University’s school of biomedical sciences, the research used mice in laboratory tests with scientists engineering mutation in a gene called RABL2 that delivers protein fuel to the engine in a sperm’s tail.

The mutation resulted in sperm tails that were 17 per cent shorter than normal and a 50 per cent reduction in sperm production.

The most striking result was that all mice with the mutated gene were rendered infertile and their sperm incapable of swimming.

“They weren’t wriggling or going anywhere, they were just twitching. With this mutation, we get motors that don’t work properly.

To be fertile, sperm need motility … or swimming ability,” the Sydney Morning Herald quoted Professor O’Bryan as saying.

For the research Professor O’Bryan collaborated with scientists from the University of Newcastle, John Curtin School of Medical Research, Garvan Institute of Medical Research and the University of Cambridge in Britain.

She said a future male pill might work to inhibit the RABL2 gene rather than change it permanently.

“The challenge with developing the male pill isn’t rendering the sperm infertile but turning them back on again,” she noted.

However, as RABL2 is also found, although in lower concentrations, in other tissues such as the brain, kidneys and liver, an inhibitor specific to the testes would need to be developed.

The discovery has been published in the journal PLoS Genetics.