A reversible male contraceptive effectively, safely and reversibly stopped sperm production in mice.
Alternatives to condoms and vasectomies are increasingly gaining momentum. The next generation of male contraceptives is already in phase 2 clinical trials in humans and now, after years of work in mice, scientists at Cornell University discovered how block sperm formation in the testicles at a critical point.
The progress was announced in a study recently in Proceedings of the National Academy of Sciences.
The contraceptive drug now tested proved to be effective, safe and reversible in male mice.
Within six weeks of stopping the injections, normal sperm production resumed, and two generations of abnormally-free offspring were born.
“We are practically the only group to defend the idea that contraceptive targets in the testicle are a viable way to interrupt sperm production”, says the corresponding author of the study and geneticist. Paula Cohen.
The team targets a crucial process called meiosiswhich takes place in the testicles of mammals, details the aforementioned magazine.
Meiosis occurs after mitosis — when stem cells become precursors to sperm — and involves a cell with two complete sets of chromosomes dividing into four new cells with half the chromosomes needed to form life. Each of these matures and becomes a sperm.
“Meiosis represents a natural checkpoint in sperm production where transient inhibition could allow precise and reversible control of fertility,” argue Cohen and his colleagues.
A The key is to avoid eliminating self-renewing stem cells before mitosis occurs, as this may lead to irreversible infertility.
However, after these stem cells have proliferated and differentiated, there is a possibility that they will escape from the testicle in the form of sperm and fertilize an egg.
Miraculous (wait for it) JQ1
O JQ1 drug acts at the perfect time. It was originally developed to prevent the proliferation of cancerous tumors, but now it also appears to be effective at prevent sperm stem cells from entering meiosis.
However, future safety assessments will now be needed before research can begin in humans. One of the concerns is that contraception comes with dangerous or unpleasant side effects.
However, Cohen’s team is confident that their study provides “a model for developing new contraceptive approaches that act in a way safe and selective in the germline”.
“We want to create something that stops sperm production without affecting male libido and secondary sexual characteristics,” adds Cohen.
A male contraceptive called , which entered a phase 2 clinical trial last year, and which ZAP had already reported interrupts sperm precursors before meiosis. It could hit the market sooner, says Science Alert.
In preclinical tests with male laboratory rats, this drug triggered a reversible infertility within four weeks after use, revealing a 99% effective in preventing pregnancy in the female rats with which the treated males mated.
