New Male Contraceptive Could Put A Speed Limit On Sperm

Scientists hope it would mean less sperm all together – with the few survivors being "abnormal" shapes.
Peter Dazeley via Getty Images

Scientists think they’ve found a new way to offer contraception to men – and this time, they’re going straight for the sperm.

More than 60 years after the female contraceptive pill was first sold in the UK (yes, you read that correctly), scientists think they’ve made a breakthrough in creating a suitable alternative for men.

A study, published in Nature Communications, honed in on mouse sperm. Scientists were able to identify a gene (called Arrdc5) which, when temporarily switched off, made the males infertile.

Male mice without that gene produced 28% less sperm that travelled at a third of the speed of those in normal mice, with 98% of their sperm coming out in abnormal shapes.

The gene in question creates an essential protein which helps form sperm. This then means sperm can’t push themselves forward, affecting their famous swimming ability to reach an egg in the uterus to fertilise it.

Scientists found that temporarily de-activating this gene did not appear to affect the mice in any other ways.

The best bit? This gene acts in the testicles of humans, too.

Scientists are now looking for a drug molecule that might be able to block the protein Arrdc5 produces for a short period of time in humans.

Dr Jon Oatley from Washington State University is the senior author of the study, and he described it as a “once-in-a-decade discovery”.

Don’t get too excited just yet, though.

Plenty more needs to be done before scientists can fully understand the Arrdc5 protein and its relationship with sperm, but it’s an optimistic start and human trials have already begun.

If it were to be successful, it would mean scientists wouldn’t have to look at interfering with testosterone levels. Previous efforts to use hormonal birth control pills for men have been criticised for triggering mood disorders and shrinking testicles.

However, Professor Richard Anderson of the University of Edinburgh – who was not part of the study – said there was still “a long way to go to make it a male contraceptive” and that it could also be a “potential cause of infertility”.

It’s not the only promising effort to tackle male fertility. Others are looking at a molecule which could target a particular enzyme which stops sperm from swimming or maturing.

When tested on mice who then did the deed, there were no impregnations and all effects of the experiment wore off after 24 hours.

Professor Jochen Buck from Weill Cornell Medicine said: “Our dream is a pill the man takes half an hour before and it would keep him essentially infertile and protected for the next 16 hours.”

Others have looked at Nesterone which needs a daily application of gel across the shoulders. It uses hormones to halt sperm production when it’s used, but the production returns when use is halted. Human trials for this have begun.