Scientists who have discovered a cell pathway, or switch, that prevents sperm from being able to swim say that an on-demand, non-hormonal male contraceptive pill may actually be a possibility.
According to studies done on mice, it keeps sperm stunned for at least a few hours, which is enough time for them to stop moving toward the egg.
It is intended to conduct many more tests, first on rabbits and then on humans.
The concept is that users could take a pill an hour prior to having sex and watch the time to see when it wears off.
It doesn't use hormones like the female contraceptive pill does.
One benefit of the strategy under investigation, according to scientists, is that it won't deplete testosterone or have any adverse effects associated with male hormone deficiency.
Instead, they are focusing on soluble adenylyl cyclase, also known as sAC, a cellular signaling protein, as the "sperm-swim" switch. The experimental male enhancement drug reduces or stops sAC.
The drug, known as TDI-11861, immobilized sperm before, during, and after mating in the early mouse study, which was supported by the US National Institutes of Health and published in the journal Nature Communications.
About three hours passed before the effect faded. It seemed to have disappeared completely after 24 hours.
Dr. Melanie Balbach from Weill Cornell Medicine in New York, one of the scientists, said it had potential as a reversible, simple-to-use contraceptive.
If it ultimately proves effective in humans, men might be able to take it only as often as necessary. They could decide on a daily basis how fertile they would be.
But experts caution that it would not offer protection against STDs. For that, condoms would be required.
"There is a pressing need for an effective, reversible oral contraceptive for men, and although many different approaches have been tested over the years, none has yet reached the market," said Prof. Allan Pacey, professor of andrology at the University of Sheffield.
"Knocking out a key enzyme in sperm that is essential for sperm movement using the method described here is a really novel concept. It is actually quite exciting that it can act and reverse so quickly.
"This could very well be the male contraceptive method we have been looking for if the trials on mice can be replicated in humans with the same degree of efficacy. ".
By blocking a protein on the surface of sperm, other researchers have been investigating a slightly different pathway to stop sperm swimming.
