From io9:
A male birth control pill that causes a temporary vasectomy By George Dvorsky
It's the 21st century and men still don't have a birth control pill to call their own. But now, scientists from Britain and Australia have figured out a way to prevent sperm from escaping during the moment of ejaculation — and without affecting sexual function.
To date, most attempts at creating a male birth control pill have focused on the development of sperm or hormonal techniques to produce dysfunctional sperm. Problem is, those approaches tend to create various health problems for men, including reduced libido or permanent alterations to the way the body produces sperm. Worst of all, some methods even cause males to transmit detrimental changes to future offspring.
But the new technique, which is described in a recent edition of PNAS, targets the autonomic nervous system. It doesn't affect the long-term viability of sperm, nor the health of males. In fact, men would keep on producing sperm as per usual, it just wouldn't join the ejaculate. It's like a vasectomy in a pill, but one that's easily reversible.
Working with mice, the researchers disabled two specific components in the nervous system (specifically, the P2X1-purinoceptor and α1A-adrenoceptor) that prevent sperm from leaving the vas deferens (a kind of holding area in the testes just prior to ejaculation). Basically, they produced mice that couldn't squeeze the sperm out of their vas deferens.
After the treatment, these mice were 100% infertile and no deleterious effects to their sexual behavior or function could be detected. The sperm looked completely normal and the mice were able to produce healthy offspring. Well, to be completely accurate, the mice did experience a slight drop in blood pressure — a side-effect that has the researchers slightly worried about potential human applications. That said, it's being seen as an important find.
"[This provides] conclusive proof of concept that pharmacological antagonism of the P2X1-purinoceptor and α1A-adrenoceptor provides a safe and effective therapeutic target for a nonhormonal, readily reversible male contraceptive," write the authors in the study.
The next step will be to find a pair of drugs that work in humans. One may already exist in the form of a drug that treats benign prostate enlargement, but the other will have to be made from scratch — a process the researchers say could take another ten years.
Read the entire study at PNAS: "Male contraception via simultaneous knockout of α1A-adrenoceptors and P2X1-purinoceptors in mice".