How a male contraceptive pill could work | John Amory

譯者: Lilian Chiu 審譯者: SF Huang

When I tell people

當我跟別人說，

that I'm trying to develop a contraceptive pill for men,

我正試著研發男性用避孕藥時，

the response usually varies along gender lines.

他們的反應通常會因性別而異。

Women say something like,

女性會說：

"Fantastic. It's about time. When?"

「好極了！也該是時候了。 何時會完成？」

(Laughter)

（笑聲）

Men have one of two responses.

男性則有兩種反應。

They either love the idea,

他們要嘛會喜歡這個點子，

or they look at me a little warily

不然就是有點謹慎地看著我，

and wonder what exactly I have in store for their testicles.

納悶我想對他們的睪丸做什麼？

(Laughter)

（笑聲）

So why does the world need a male pill?

所以，為什麼世界 需要男性避孕藥丸？

Well, what if I told you

嗯，如果我跟你說，

that of the six million pregnancies annually in the United States,

美國每年六百萬個懷孕案例當中，

three million of them are unintended?

有三百萬個都是不小心 發生的，你怎麼想？

That's half.

那佔了一半。

That's a really surprising number.

這個數字很驚人。

And those three million unintended pregnancies

而那三百萬個不小心懷孕的案例

account for the vast majority of the more than one million abortions

是美國每年超過一百萬個

annually performed in the United States.

墮胎案例的主要原因。

Happily, the rate of unintended pregnancy has fallen in the last few years

值得高興的是，最近幾年， 不小心懷孕的比率

by about 10 percent.

下降了約 10%。

This is because more women are using effective, long-acting,

這是因為有更多女性 會使用有效、長效

reversible forms of contraception.

且可逆式的避孕方式。

But we still have a long way to go.

但我們還有很長的路要走。

One approach that's finally becoming a real possibility

有一個快要實現的方法

is better contraceptive options for men.

就是提供男性更好的避孕工具。

Think about it.

試想看看。

We have over a dozen methods of contraception for women:

我們有十多種給女性的避孕方法：

pills, patches, IUDs, shots, sponges, rings, etc.

藥物、貼布、子宮內避孕器、 注射、海棉、避孕環等等。

For men, we've had the same two options

對男性而言，

超過一百年來，都只有兩種選擇：

for more than a hundred years:

condoms and vasectomy.

保險套和輸精管切除術。

Despite having only two options,

儘管只有兩種選擇，

both of which have significant drawbacks,

兩者都有明顯的缺點，

men currently account for 30 percent of all contraceptive use,

目前所有避孕工具的使用中， 有 30% 是由男方來做避孕，

with 10 percent of couples relying on vasectomy

其中 10% 用輸精管切除術，

and 20 percent of couples using condoms.

20% 使用保險套。

Why are 20 percent of couples relying on condoms for contraception

為什麼明明保險套的 一年失效率超過 15%，

when condoms have a one-year failure rate of over 15 percent?

卻有 20% 的伴侶選擇靠它來避孕？

It's because many women can't either safely take

那是因為，許多女性 無法安全地採用

currently available female contraceptives, for reasons such as blood clots,

現今的女性避孕工具， 理由包括血栓，

or they can't tolerate the side effects.

或是她們無法忍受副作用。

So if we think a male contraceptive would be useful, the next question is:

如果我們認為男性的避孕工具 會很有用，下一個問題就是：

How do we go about developing one?

我們要如何著手開發它？

Well, there's two general approaches.

嗯，有兩種常用的方法。

The first approach is to try and interfere

第一種是嘗試阻擾

with the way the sperm swim towards or bind to the egg.

精子游向卵子或和卵子結合。

This approach turns out to be really difficult,

結果發現這種方法很困難，

because it's hard to get enough medication in the small volume of the ejaculate

因為一次射精的量很小， 使其很難達到足夠的藥物劑量

and have it still work inside the female reproductive tract.

在女性的產道中能持續發揮功效。

This is why there's been a lot more work done on the second approach,

這就是為什麼比較多人 致力於第二種方法，

which is turning off sperm production entirely.

就是完全關閉精子的生產。

This is also challenging.

這也很有挑戰性。

Why? Turns out that men make a lot of sperm.

為什麼？結果發現 男性會製造很多精子。

(Laughter)

（笑聲）

Men make a thousand sperm every second

男性每秒鐘會製造一千個精子，

and to have an effective contraceptive,

若要達到避孕的效果，

you need to get that level of sperm production

必須要把精子產量降低

down to one percent of its normal value.

到正常值的 1%。

The good news is, this is possible,

好消息是，這的確有可能辦到，

almost.

幾乎有可能。

The most studied approach has been to use hormones to suppress sperm production.

最多人研究的方法， 是用荷爾蒙來抑制精子的製造。

Testosterone and progesterone, when administered together,

如果同時施用睪丸素和黃體酮，

will suppress the signals from the brain to the testes to make sperm,

就能夠抑制從大腦發送到睪丸 要求製造精子的訊號，

and in about 90 percent of men,

在大約 90% 的男性身上，

sperm production after three to four months will stop.

三到四個月後精子製造就會停止。

Unfortunately, 10 percent of men don't respond to these hormonal regimens

不幸的是，10% 的男性 對這類荷爾蒙方案沒有反應，

for reasons that aren't understood.

目前原因還不明。

For the last several years, my colleagues and I

過去數年間，我同事和我

have been taking a different approach to male contraceptive development,

採用了一個不同的方法 來開發男性避孕工具，

one that doesn't involve the administration of hormones.

我們的方法不需要用到荷爾蒙。

Specifically, we are looking to block the function of vitamin A in the testes.

明確來說，我們想做的是 阻擋睪丸中維生素 A 的功能。

Why? Well, for over 90 years it's been known

為什麼？過去九十年間 我們一直都知道

that you need vitamin A to make sperm.

需要維生素 A 才能製造精子。

Animals who are deprived of vitamin A in their diet

動物的飲食若去除維生素 A，

stop making sperm

牠們就會停止製造精子，

and restart making sperm again when the vitamin A is reintroduced.

再度提供維生素 A 時， 才又會重新開始製造。

The vitamin A that we ingest

我們攝取的維生素 A

is converted by a family of enzymes to something called retinoic acid.

會由某些酶轉換成為 所謂的維生素 A 酸。

One of these enzymes is found only in the testes.

在這些酶當中， 就只有一種酶存在於睪丸中。

It's this enzyme that we are attempting to block.

我們打算阻擋的就是這種酶。

The blockade of this enzyme should deprive the testes of retinoic acid

若能阻擋這種酶，就能讓 睪丸中不再有維生素 A 酸，

and stop sperm production

進而阻止精子產生，

without affecting vitamin A's functions elsewhere in the body.

且不會影響維生素 A 在身體其他地方的功能。

We're testing this approach in animals

此方法正在進行動物測試，

and hope to move to human testing soon.

希望很快可以進入人體實驗階段。

Obviously, the impact of such a male contraceptive

很顯然，這種男性避孕工具的影響

would go well beyond reproductive biology.

會遠遠超過生殖生物學的範圍。

It's interesting to speculate about the effect that it would have

可以來推測看看 它對於男女之間的關係

on relationships between men and women.

有什麼影響，應該很有趣。

One intriguing possibility

挺有吸引力的一點

is that a man could monitor his contraceptive status over time.

是男性可以隨時監控他的避孕狀態。

In the last several years,

在過去數年間，

two groups have introduced home sperm-testing devices

有兩個團體都推出了 居家型精子測試機，

that are iPhone-based

以 iPhone 為基礎，

and that are easy to use.

很容易使用。

A man could test his sperm count and share the result with his partner.

男性可以測出他的精子數量， 和他的另一半分享結果。

If the man's sperm count were zero,

如果他的精子數量是零，

the man and his partner would feel very comfortable

他和他的另一半就可以非常放心地

relying on his contraceptive.

仰賴他的避孕工具。

A tool like this, coupled with a male contraceptive,

像這樣的工具， 再搭配上男性避孕工具，

could greatly increase the role for men in preventing unintended pregnancy.

就能讓男性在預防意外懷孕上 扮演更重要的角色。

The researchers who are working on male contraception

致力於男性避孕的研究者

are trying to create a better future for couples,

正在試圖為伴侶們 創造更美好的未來，

a future where contraception is no longer considered just "a woman's issue,"

一個避孕不再只是 「女人的事」的未來，

rather an issue for couples to decide together.

而是伴侶雙方要一起決定的議題。

So why does the world need a male pill?

所以，為什麼世界 需要男性避孕藥丸？

Well, I believe that a male pill

我相信，男性避孕藥丸

will help reduce the stubbornly high rates of unintended pregnancy and abortion

能協助減少一直居高不下的 意外懷孕比率以及墮胎率，

and allow men to equally participate

並讓男性有平等的機會參與

in contraception.

避孕工作。

Thank you.

謝謝。

(Applause)

（掌聲）