Like flies in jam
Blocking the process of sperm liquefaction will become a new method of contraception
Maria Azarova, Naked Science
When they talk about birth control, the first thing they remember is pills for women. Meanwhile, scientists continue to work on similar remedies for men. One of the possible options is blocking the process of sperm transition from a gel—like mass to a more liquid state, in which it is easier for spermatozoa to move, pass the cervix and reach the egg. This method of non—hormonal contraception - including for women — was proposed by a research group from Washington State University and the University of Missouri in Kansas City (USA). The results of the work are published in the journal Biology of Reproduction (Anamthathmakula et al., Blocking serine protease activity prevents Semenogelin degradation leading to Hyperviscous seeds in humans).
According to scientists, contraceptives dispensed today without a prescription — condoms and spermicides (substances that destroy sperm) — do not work on average in 13-21% of cases. Intrauterine hormonal contraception and birth control pills are more effective, but they can cause undesirable side effects and are not always affordable. Partly because of this, the rate of unwanted pregnancies in the world is estimated at 48%. As a result, unsafe abortions and about 47 thousand episodes of maternal mortality annually.
The authors of the new article have been working on their method of contraception since 2015, when during another study it turned out that some female mice could not get pregnant. The fact was that the sperm of the males remained viscous. Subsequently, the scientists tried to block the liquefaction process: with the help of a nonspecific protease inhibitor called AEBSF, they managed to disrupt the movement of sperm and reduce fertility in the subjects.
Now the researchers have tried to reproduce the results on human samples. As it turned out, AEBSF does have a contraceptive effect, but the question remained whether this was due to the toxicity of the drug. The specialists decided to use the antibody to target an organ—specific protein - prostatic specific antigen (PSA), which acts as a chymotrypsin-type protease and is necessary for dilution of the ejaculate. It is secreted by the prostate gland in humans, but not in mice, and enters sperm, prostate secretions and blood in small quantities.
A control sample of human sperm (left) compared to a sample treated with AEBSF to block sperm dilution (right). A drawing from the press release Trapping sperm in semen's natural gel could lead to new contraceptive.
After ejaculation, PSA acts on semenohelin, a protein of human sperm coagulate. "Semyonogelins create a gel-like network with proteins that "catches" sperm. The PSA splits this mesh and the sperm becomes free," explains Prashant Anamtatmakula from the University of Missouri-Kansas City. "Due to the PSA—antibody inhibitor, we have shown that we can block this dilution." As a result, the sperm, fresh samples of which were collected from healthy men, managed to remain viscous and thereby detain most of the sperm.
Now the team wants to identify more specific low molecular weight inhibitors that can effectively prevent PSA's ability to dilute sperm without harmful side effects. The goal is to create an affordable contraceptive that can be used along with condoms to exclude fertilization.
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