Preventing unwanted pregnancy is a shared responsibility between both sexes, but what if men had the same contraceptive options as women?

New research in male mice expands this possibility by examining a drug that halts sperm production, a development that may give rise to an oral contraceptive for men one day.

Featured in the journal Endocrinology, the experiments reveal that a specific compound — called BMS 189453 — successfully blocks the retinoic acid receptors needed to metabolize vitamin A. The vitamin assists with the division and maintenance of sperm cells. Rather than using hormones, as seen in female contraceptives, the drug used by the research team targets the production of vitamin A, which acts as a growth factor in testes.

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Despite the role vitamin A plays in maintaining good vision, researchers say it uses a different pathway for sperm production and the drug would not negatively affect men's vision.

In the study, researchers gave mice a range of daily doses of the compound for different time frames. They found that the drug interrupted sperm production and caused sterility between two and four weeks' time. Unlike permanently altering a mouse's genes to make it sterile, the compound created temporary effects and did not seem to prevent mice from producing healthy offspring months after the drug wore off.

Previous research on male contraceptives has fallen short because of possible side effects and lack of consistency across men. Hormonal treatments run the risk of reducing libido and can even increase prostate growth. It's also difficult to create hormone options that could be administered orally rather than as an injection.

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The authors, from Columbia University, believe their results may lead to the development of an oral contraceptive for men without the side effects and dosage issues of hormone treatments. But scientists need to measure the long-term effects of the drug before moving forward. Also, it's unclear whether the drug will maintain its reversibility over longer periods of time.

Giving men more options to prevent unwanted pregnancies is a move in the right direction, but using oral contraceptives doesn't reduce people's chances of acquiring sexually transmitted infections. Practicing safe sex is still important, according to the U.S. National Library of Medicine.

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