A compound that renders sperm motionless has proven promise as a reversible type of contraception in mice.

The alternatives of contraception for males are restricted to utilizing condoms or having a vasectomy. “We undoubtedly want extra choices,” says Martin Matzuk at Baylor School of Drugs in Texas.

Now, he and his colleagues have recognized a possible new goal — a protein expressed by the gene STK33 that’s present in excessive concentrations within the testes of mice and males.

“Within the absence of the STK33 protein, mice and human sperm wind up having very irregular sperm tails, which causes motility defects,” says Matzuk. Research have additionally proven that mice and men that lack or have a mutated version of the STK33 gene are infertile as a consequence of having malformed sperm.

To establish a compound that might bind to and inhibit the exercise of the STK33 protein, the workforce combed by way of a library containing billions of chemical substances, searching for an acceptable molecule. Ultimately, they discovered a candidate referred to as CDD-2807.

Subsequent, the workforce injected six male mice with CDD-2807 twice a day for 21 days and one other seven male mice as soon as a day for a similar period of time. After these three weeks, they housed all of the male mice with females, whereas persevering with the remedy for round one other 40 days.

Just one mouse throughout each teams had impregnated a feminine by the tip of the 40 days. That mouse solely sired one pup, whereas mice litters sometimes have as much as six pups, an indication that the remedy nonetheless decreased its fertility. No unwanted effects had been recorded. Three weeks after stopping the remedy, the researchers discovered that the mice’s infertility reversed they usually had been in a position to reproduce as regular.

Matzuk says they now hope to check an oral model of the remedy in primates.

Jochen Buck at Cornell College in New York says the paper is “very strong”, however {that a} not-yet-approved gel referred to as NES/T, containing artificial progesterone and testosterone, may fit sooner than concentrating on STK33 in individuals. The identical would most likely even be true for a contraceptive that targeted a protein known as retinoic acid receptor alpha, which is concerned in sperm manufacturing, he says.