Fuel clock drives feeding

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Hi All. Here is another take on a story previously posted about.

Cheers, Al.

http://www.nature.com/nsu/021104/021104-2.html

Florida, November, 2002

Fuel clock drives feeding

Metabolic clock mutants give up food and siestas.

04 November 2002

HELEN PEARSON

Researchers have created a

mouse that lacks the drive to

eat or siesta. The findings

hint at the existence of a

controversial body clock

driven by metabolism.

Night and day are thought to

keep our bodies ticking to a

24-hour beat. But

McKnight, of the University of

Texas Southwestern Medical

Center in Dallas, and his

group have evidence that a

second, fuel-driven timer

may be just as critical.

Mice that are modified to

lack a gene in the proposed

metabolic clock simply starve

to death when their

mealtimes are altered, he

told the Society for

Neuroscience meeting 2002,

this week in Orlando, Florida. Rodents normally feed at night,

but change their activity if food is only available during

daylight.

The mutant mice also stopped taking naps. Normally, rodents

rest from nocturnal wheel-running after a seven-hour stint;

mutants strode on for nine hours. " It suggests a nap is

genetically programmed, " says McKnight.

The confused mice lack a gene called NPAS2. In normal mice,

this gene is switched on at night when the brain is alert and

chemical energy is abundant in the cell, McKnight's team

found last year1,2. NPAS2 switches other genes on and off,

and is chiefly active in the front of the brain, where senses

and emotions are processed.

Researchers agree that there are different clocks running in

different parts of the body - these are generally thought to be

synchronized with the light clock in the brain region called the

suprachiasmatic nucleus.

McKnight argues that, at least when mealtimes are altered,

the metabolic clock takes charge instead. Mice without NPAS2

are unable to reset their mealtimes. " They are slaves to

light, " says McKnight. The two timekeepers normally strike a

balance, he adds.

NPAS2 may influence the motivation centre that drives

animals to seek food, suggests perception researcher

Berson of Brown University in Rhode Island. " I'd be surprised

if that wasn't part of the story. "

References

1.Reick, M., , J.A., Dudley, C. & McKnight, S.L. NPAS2: an

analog of clock operative in the mammalian forebrain. Science,

293, 506 - 509, (2001). |Homepage|

2.Rutter, J., Reick, M., Wu, L.C. & McKnight, S.L. Regulation of

clock and NPAS2 DNA binding by the redox state of NAD

cofactors. Science, 293, 510 - 514, (2001). |Homepage|

© Nature News Service

Alan Pater, Ph.D.; Faculty of Medicine; Memorial University; St. 's, NL

A1B 3V6 Canada; Tel. No.: (709) 777-6488; Fax No.: (709) 777-7010; email:

apater@...