American scientists are one step closer to successfully developing a male contraceptive. Laboratory studies show that the contraceptive causes temporary infertility without harming sexual desire. One of the challenges is to develop a successful contraceptive that can pass from the blood into the testes, explained the research team at the Dana Farber Institute in Boston. Scientists are testing the drug JQ1. It targets a protein that exists only in the testicles and is essential for sperm production. What happens during use? Experts observe a decrease in the quality of sperm, which accordingly has an effect on fertility. The action of the tablet causes the testicles to shrink due to reduced sperm production. They are also less mobile, scientists note. NEWS_MORE_BOX The effect is also found to be reversible. When the medication is discontinued, fertility returns. The tested compound leads to a rapid and reversible reduction in sperm count and motility, and has a strong impact on fertility, explains Dr. James Bradner of the research team. The scientists are about to move on to the next stage of trials to prove the safety and effectiveness of the medication in humans. The study was published in the journal Cell.