評(píng)論
打印
Men make a thousand sperm every second and to have an effective contraceptive,
每秒中，男性可生產(chǎn)出一千個(gè)精子，所以有效的避孕藥
you need to get that level of sperm production down to one percent of its normal value.
必須把這個(gè)精子生產(chǎn)率降到正常值的1%。
The good news is, this is possible, almost.
好消息是，這是可以做到的，幾乎可以。
The most studied approach has been to use hormones to suppress sperm production.
被研究最多的方法是用激素抑制精子生產(chǎn)。
Testosterone and progesterone, when administered together,
睪丸酮和黃體酮，當(dāng)一起被服用的時(shí)候，
will suppress the signals from the brain to the testes to make sperm,
會(huì)抑制大腦發(fā)射的讓睪丸生產(chǎn)精子的信號(hào)，
and in about 90 percent of men, sperm production after three to four months will stop.
在90%左右的男性中，這個(gè)方法能使精子的產(chǎn)生在三四個(gè)月后停止。
Unfortunately, 10 percent of men don't respond to these hormonal regimens for reasons that aren't understood.
不過很遺憾，還有10%的男性不會(huì)對(duì)這些激素療法做出反應(yīng)，原因我們目前還不了解。
For the last several years, my colleagues and I have been taking a different approach to male contraceptive development,
過去幾年里，我和我的同事采用了另一種解決男性避孕問題的方法，
one that doesn't involve the administration of hormones.
一個(gè)不需要激素療程的方法。
Specifically, we are looking to block the function of vitamin A in the testes.
具體來說，我們?cè)谘芯咳绾巫柚共G丸中維生素A的活動(dòng)。
Why? Well, for over 90 years it's been known that you need vitamin A to make sperm.
為什么這么做呢？90多年來，我們一直都知道你需要維生素A來生產(chǎn)精子。
Animals who are deprived of vitamin A in their diet stop making sperm
飲食中缺乏維生素A的動(dòng)物會(huì)停止生產(chǎn)精子，
and restart making sperm again when the vitamin A is reintroduced.
當(dāng)維生素A被重新引進(jìn)飲食后，它們又會(huì)重新開始精子的生產(chǎn)。
The vitamin A that we ingest is converted by a family of enzymes to something called retinoic acid.
我們攝入的維生素A會(huì)被一個(gè)類別的酶轉(zhuǎn)化成視黃酸。
One of these enzymes is found only in the testes.
其中一種酶只在睪丸才有。
It's this enzyme that we are attempting to block.
我們?cè)噲D限制的就是這種酶。
The blockade of this enzyme should deprive the testes of retinoic acid
阻斷這個(gè)酶應(yīng)該可以使精子喪失視黃酸，
and stop sperm production without affecting vitamin A's functions elsewhere in the body
從而停止精子生產(chǎn)，同時(shí)并不影響維生素A在身體其他部分的功能。
We're testing this approach in animals and hope to move to human testing soon.
我們正在動(dòng)物體內(nèi)測(cè)試這個(gè)方法，希望不久后可以在人體內(nèi)測(cè)試。
