Scientists develop a nonhormonal method that temporarily stops sperm production, offering hope for new male contraception
A new study brings male contraception closer to reality, showing that sperm production can be safely paused and later restored in mice.
The nonhormonal compound JQ1 blocked sperm formation without lasting effects, and fertility returned after treatment. Experts say this could provide a reliable option beyond condoms and vasectomies.
The findings are published in the Proceedings of the National Academy of Sciences.
Cornell study shows targeting meiosis can safely and reversibly halt sperm production in mice
Cornell scientists conducted a six-year proof-of-principle mouse study and found that interrupting a key step in meiosis, which produces sex cells, temporarily halted sperm production.
The scientists used JQ1, a small molecule inhibitor developed to study cancer and inflammation. Although JQ1 is unsuitable for treatment due to neurological side effects, it disrupts prophase 1 of meiosis (when chromosomes pair and exchange genetic material). This enabled researchers to show that targeting meiosis can safely and reversibly halt sperm production.
“We’re practically the only the group that’s pushing the idea that contraception targets in the testis are a feasible way to stop sperm production,” said Paula Cohen, professor of genetics and director of the Cornell Reproductive Sciences Center.
“Our study shows that mostly we recover normal meiosis and complete sperm function, and more importantly, that the offspring are completely normal,” Cohen said.
Developing a non-hormonal male contraception
Current male contraception options are limited to condoms and vasectomies. Vasectomies are seen as long-term, so many men avoid the procedure despite its reversibility.
To address these limitations, Cohen and her research team focused on meiosis to ensure that sperm production could be fully stopped while still allowing recovery later, thus preserving overall reproductive health.
“We didn’t want to impact the spermatogonial stem cells, because if you kill those, a man will never become fertile again,” Cohen said. Also, once sperm entered spermiogenesis, there was a risk that viable sperm would leak out and fertilise an egg.
JQ1 disrupts meiosis, the process of cell division that produces sperm, during proposal 1, leading to cell death at this stage. It also blocks the gene activity required for future steps in sperm development.
Male mice received JQ1 for three weeks, and sperm production stopped completely. Once the treatment had ended, recovery began, and healthy sperm production returned within six weeks. The mice were confirmed to be fertile. The researchers bred the mice, and their offspring were healthy and able to reproduce.
“It shows that we recover complete meiosis, complete sperm function, and more importantly, that the offspring are completely normal,” Cohen said.
The researchers emphasised that if JQ1 were developed for human use, this type of male conception could be delivered as an injection every 3 months or, potentially, as a patch to maintain its effectiveness.
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