Nettles might put sting into sperm

Stinging nettles could be the source of an oral male contraceptive.

A study published in the online science journal PLOS ONE has found that extract from the leaves of stinging nettle (Urtica dioica) blocks a crucial protein in sperm transport. The nettle extract also inhibited fertility in male mice.

The researchers, who are based at Monash University, had previously found two proteins that together are essential to the transport of sperm, called α1A-adrenoceptor and P2X1-purinoceptor. Knocking out these proteins reduced fertility in mice, without affecting their sperm viability or any other “male characteristics.”

They suspected that stinging nettle extract could block one of these proteins: P2X-purinoceptor.

“In this study we were able to conclude that stinging nettle leaf extract reduces contractility of urinary and genital smooth muscle by acting as a P2X1-purinoceptor antagonist,” says lead researcher Dr Sab Ventura, from the Monash Institute of Pharmaceutical Sciences.

The researchers found that the extract inhibited the fertility of mice when fed to them, without affecting their behaviour or any other health indicators. It wasn’t completely effective: mouse fertility was only reduced by 53% compared to a control.

Read more: Male contraceptive effective in mice

Next, the researchers plan to find out which compound, or compounds, in the stinging nettle extract are inhibiting the protein. They think it could be a useful starting point for an oral male contraceptive.

“Unfortunately, there has been a widespread perception that birth control is a women’s problem rather than a men’s problem,” says Ventura.

“However research led by the Male Contraceptive Initiative shows that the majority of men are willing to take control over contraception – we just need to give them the opportunity to do so.”

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