Name: 【TED】John Amory: How a male contraceptive pill could work (How a male contraceptive pill could work | John Amory)
Uploaded: 2018-05-22T21:14:29.000Z
Duration: 6 min 24 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

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

the response usually varies along gender lines.

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

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

And those three million unintended pregnancies

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

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

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

One approach that's finally becoming a real possibility

We have over a dozen methods of contraception for women:

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

both of which have significant drawbacks,

men currently account for 30 percent of all contraceptive use,

with 10 percent of couples relying on vasectomy

Why are 20 percent of couples relying on condoms for contraception

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

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

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

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

The first approach is to try and interfere

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

This approach turns out to be really difficult,

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

and have it still work inside the female reproductive tract.

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

which is turning off sperm production entirely.

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

you need to get that level of sperm production

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

Testosterone and progesterone, when administered together,

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

sperm production after three to four months will stop.

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

For the last several years, my colleagues and I

have been taking a different approach to male contraceptive development,

one that doesn't involve the administration of hormones.

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

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

Animals who are deprived of vitamin A in their diet

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

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

One of these enzymes is found only in the testes.

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

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

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

Obviously, the impact of such a male contraceptive

would go well beyond reproductive biology.

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

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

two groups have introduced home sperm-testing devices

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

the man and his partner would feel very comfortable