A new type of human contraceptive is on the horizon. Recently, a compound that immobilizes sperm has shown promise in successful trials on mice, offering a reversible method of contraception. The related study was published in "Science."
The movement ability of sperm plays a crucial role in male fertility. Image Source: Shutterstock
Male contraception options are currently limited to condoms or vasectomy. "We really do need more choices," says Martin Matzuk from Baylor College of Medicine in the United States.
Matzuk and his colleagues have now identified a potential new target - a protein expressed by the STK33 gene, which is highly abundant in the testes of mice and men.
"In the absence of the STK33 protein, mice and human sperm end up with highly abnormal tails, leading to motility defects," Matzuk explains. Research also indicates that mice and men lacking or carrying mutated versions of the STK33 gene are infertile due to sperm abnormalities.
To identify a compound that can bind to and inhibit the activity of the STK33 protein, the research team screened billions of chemical compounds to find the right molecule. Eventually, they found a candidate called CDD-2807.
Next, the research team injected CDD-2807 into 6 male mice twice a day for 21 days, while another 7 male mice were injected once a day for the same duration. After three weeks, all male and female mice were placed together and the treatment continued for about 40 days.
At the end of the 40 days, only one mouse from the two groups impregnated a female. This mouse gave birth to only one pup, whereas a typical litter of mice consists of 6 pups, indicating that the treatment still reduced the fertility of the mice with no recorded side effects. Three weeks after stopping the treatment, researchers found that the infertility in mice had been reversed, and they were able to reproduce normally.
Matzuk mentioned that they now hope to test this therapy on primates.
Jochen Buck from Cornell University in the United States stated that this paper is "very reliable," but an unapproved gel called NES/T, containing synthetic progestin and testosterone, may act faster in the human body than targeting STK33. He also suggested that a contraceptive targeting a protein called retinoic acid receptor alpha, which is related to sperm production, might be effective.
For more information, refer to the related paper: https://doi.org/10.1126/science.adl2688
