Doctors have invented a method of reliable male oral contraception
Reliable, masculine
Such promises are made by Australian doctors who have achieved complete loss of fertility, so far – on the example of rodents. "The search for viable means of male contraception for many years has remained a difficult task for medicine for many years," says Sabatino Ventura from Monash University (Australia), author of an article in the journal Proceedings of the National Academy of Sciences describing a fundamentally new method of contraception (White et al., Male contraception via simultaneous knockout of alfa1A-adrenoceptors and P2X1-purinoceptors in mice).
Unlike the tasks of female contraception, in which scientists try to block one egg by various methods, the situation is more complicated with men: it is necessary to stop (or immobilize) each of the fifteen hundred sperm cells produced every second in the male body.
Experiments with hormonal drugs have shown their low effectiveness and an abundance of side effects. Experiments with drugs designed to reduce the production of spermatozoa from a special epithelium in the convoluted tubules of the testicles did not bring reliable results either – the so-called hemato-testicular barrier interferes, which does not allow spermatozoa to contact with blood, and therefore protects them from the penetration of drugs.
"Previously, strategies focused on hormonal targets or mechanisms that cause non–viable sperm to be produced, but they often affected male sexual activity and caused long-term irreversible effects in the ability to conceive," Ventura explained.
In addition, the problem is that the method of effective male contraception that has not yet been found should be reversible and not lead to long-term damage to the germ cells in case a man suddenly wants to have children. Instead of killing or immobilizing spermatozoa, Australian scientists suggested simply not letting them go where these cells are so eager to get to.
The spermatozoa formed in the testicles are contained in the epididymis – a long narrow duct. At the moment of ejaculation, the muscles push the germ cells from this duct into the vas deferens in the direction of the urethra.
Signals that cause muscles to contract are received by two receptors on the surface of these muscles – alfa1A-adrenoreceptor and P2X1-purinoreceptor. To deprive mice of the ability to reproduce, Ventura and colleagues bred animals in which the work of these receptors was suppressed.
It turned out that mice with non-functioning receptors continued to produce viable sperm, continued to mate at least as often as normal mice, but the males became completely infertile. In the absence of receptors, the muscles carrying sperm simply stopped contracting, but this did not affect the sexual behavior and activity of rodents in any way.
"We have shown that the simultaneous destruction of two proteins controlling sperm removal at the moment of ejaculation causes complete infertility, but does not lead to loss of sperm viability, problems with sexuality or health," Ventura believes.
Two blocked receptors play a role in the functioning of the cardiovascular system, which is probably why a slight decrease in pressure was noted in the bred mice, which may become a side effect.
The fact that the vas deferens are located outside the hemato-testicular barrier allows us to hope that these receptors can be affected by oral contraceptives. By the way, there are already medications that block the alfa1A-adrenoreceptor for the treatment of benign prostate tumors. According to the authors of the discovery, in any case, the appearance of effective contraceptives based on this effect will be preceded by years of clinical trials. "The next step is the development of male oral contraceptives, effective, safe, with rapid reversibility," Ventura is sure.
Portal "Eternal youth" http://vechnayamolodost.ru04.12.2013