In brief–

Research news and discovery

THE appetite-suppressing side

effect of ecstasy may reveal why

people with anorexia nervosa

can lose the physical urge to eat,

despite really needing the energy.

Valerie Compan at the national

centre for scientific research in

Montpelier, France, and her

colleagues wondered if the brain’s

reward centre – the nucleus

accumbens (NAcc), which is

stimulated by ecstasy – might

found. And when mice genetically

engineered to lack serotonin-4

receptors were given ecstasy, they

ate normally, suggesting ecstasy

affects appetite through these

receptors (Proceedings of the

National Academy of Sciences,

DOI: 10.1073/pnas0701471104).

Compan says the research

emphasises that anorexia is more

than psychological, and may point

to drug targets for its treatment.

also play a role in anorexia.

They stimulated serotonin-4

receptors in the NAcc of mice,

which reduced their urge to eat,

but also boosted levels of a peptide

called CART in the animals’ brains.

CART levels are also higher in the

blood of anorexic women , and

drugs like ecstasy are also known

to raise CART levels in people.

Blocking the production of

CART increased appetite, the team

MOST babies can detect the

difference between sounds like

“bih” and “dih” by the age of

17 months. Not so children raised

in bilingual households, it seems.

Christopher Fennell’s team at

the University of Ottawa in Canada

and his colleagues monitored

infants aged 14, 17 and 20 months

as they watched a video of two

characters: “bih”, a plasticine

crown, and “dih”, a plastic

molecule. Later, the babies saw

another video, but this time the

crown was named “dih”. Babies

who spent significantly longer

looking at the crown were judged

to have noticed the difference.

While monolingual babies

can detect such differences by

17 months, bilingual babies were

20 months old before they noticed

it (Child Development, vol 78, p

1510). Fennell thinks the demands

of learning two languages mean

babies don’t notice differences

until later – although there is no

difference in age at first word.

Bilingual blur

WHAT caused a fleeting but highly

powerful burst of radio waves that

originated beyond the Milky Way?

Suspects so far include the merger

of neutron stars and the complete

evaporation of a black hole.

The burst was discovered by

David Narkevic, a student at West

Virginia University in Morgantown,

while searching data from the

Parkes radio dish in Australia.

Finding more such events could

help detect ripples in space-time –

which should occur when neutron

stars merge. These ripples are

predicted by general relativity

but have never been observed.

In 5 milliseconds the burst

released as much energy as the

sun puts out in a month. Black

holes are supposed to spew out

a burst of energy when they die,

so that is one possible scenario.

The last gasp of a

dying black hole?

TEA drinkers beware. Too much of the wrong kind can add

significantly to the amount of fluoride you consume, with

the tea in just four cups supplying up to one-third of the

maximum safe daily amount.

In places where people ingest too little fluoride, it is

added to water supplies to strengthen tooth enamel and

prevent cavities. But some 200 million people worldwide –

mainly in hot countries where deep wells are bored into

fluoride-rich rocks, and people drink lots of water – take in

too much, and as a result are affected by fluorosis, which

makes their teeth brittle and discoloured. In some parts of Sri

Lanka drinking water contains up to five times the maximum

fluoride recommended by the World Health Organization,

and some 98 per cent of people are affected by fluorosis.

Rohaha Chandrajith and colleagues at the University of

Peradeniya in Sri Lanka point out that no one has ever

assessed the risk of tea, even though tea plants accumulate

fluoride from the soil and some Sri Lankan people drink it

instead of water. The team found that every grade of local

tea yielded a drink with more fluoride than the water it

was made with (Environmental and Geochemical Health,

vol 29, p 429). Just four cups of tea a day would contain

1.36 milligrams of fluoride over and above what was in the

water. The WHO’s recommended maximum is 4 milligrams.

CHR

IS S

TOW

ERS/

PAN

OS

www.newscientist.com 6 October 2007 | NewScientist | 21

Pick your tea with care, or you risk fluoride poisoning

Ecstasy may inspire drugs to treat anorexia

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