In another breakthrough discovery, scientists have identified a new protein found in male sperm, the findings were published in Science earlier this week.
Researchers further found that when they exhausted that specific protein in mice, the males became infertile while still capable of having sex. This breakthrough could actually lead to the invention of a male contraceptive in the future.
Birth control pills have been one of the widely used female contraceptives since its inception decades ago. But there has never been a male equivalent.
Previous studies have found that the protein called calcineurin - which helps activate immune cells - also plays a vital role in male fertility. But because there are several kinds of protein - called isoforms - in the testes, it has been troublesome to identify the actual function of each one.
According to IFL Science:
"But recently, researchers found evidence that calcineurin isoforms that contain a catalytic subunit called PPP3CC and a regulatory sub unit called PPP3R2 are only found in cells that form sperm. PPP3CC joins up with PPP3R2 to form the calcineurin complex during sperm production.
"So, Osaka University's Masahito Ikawa and colleagues examined these sperm-specific calcineurin subunits in more detail. When they knocked out the gene for PPP3CC in male mice, this created a mutation in calcineurin that made the males infertile - though they were still able to copulate."
Sperms that were deprived of the PPP3CC subunit weren't able to swim as well, in addition to failing to penetrate the membrane that surrounds the egg. Additionally, they couldn't fertilize eggs using in-vitro fertilization as well.
After examining sperm motility with the use of computer-assisted sperm analysis, it was found that "the midpiece that connects the head with the tail of sperm lacking PPP3CC don't bend the way normal sperm do during a process called hyperactivation," which is basically necessary for it to penetrate the egg membrane.
There are at least two kinds of immunosuppressant drugs - commonly used for post-organ transplants - are known to inhibit the protein.
Apparently, those treated with these drugs for at least four or five days also made males infertile with inflexible midpieces of sperm. Turns out, the protein is vital for sperm that is still developing, but not for those that have matured.
The fertility, sperm motility, and midpiece flexibility in the drugged male mice recovered a week after the researchers stopped administering the drug.
