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- BRECKENRIDGE, CO (Reuters
Health) - Food, sex, and illicit drugs appear to share brain pathways that
spell ''reward,'' which may explain why it is possible to become addicted
to these things. At the 33rd annual Winter Conference on Brain Research,
a panel of experts discussed animal studies that show ``a degree of interchangeability
between eating food, engaging in mating, and self-administering drugs.''
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- ``Common neurochemicals mediate food and drug response,''
said Dr. Marilyn Carroll of the University of Minnesota. Neurochemicals
are substances in the brain. ``In animal studies, sweet and fat preferences
predict alcohol self-administration. Giving preferred foods blocks drug
self-administration. In humans, cigarette abstinence results in weight
gain and ethanol abstinence is associated with eating more sweets.''
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- Carroll's research showed that monkeys on food-restrictive
diets use more cocaine than monkeys given ample food. Giving monkeys glucose
solution instead of plain water also reduces their cocaine use. Relapse
after withdrawal is greater in food-restricted animals. She concluded that
in animals, food and sweets decrease first-time drug use by 40% to 50%.
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- ``We're trying very hard to find medications that help
in drug addiction,'' said Carroll. ``Some medications work a little, but
none work very well. A combination of food and medication decreases drug
use 80% to 90% in animals. Medicine combined with other rewards works best
in humans.''
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- Dr. Philippe DeWitte of the University of Lourain in
Belgium studied the effect of exercise on alcohol use. A substance called
taurine, which regulates calcium efflux and influx, increases after running.
Runners have higher levels of taurine after a marathon or a 100-kilometer
run.
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- ``Heavily alcoholized rats have increased taurine,''
said DeWitte. ``As do extreme runners. We can use aerobic exercise to increase
taurine and reduce alcohol use,'' he added.
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- Dr. Elaine Hull, from the State University of New York
at Buffalo, has studied the effect of the neurotransmitters dopamine and
serotonin on sexual behavior in male rats. Her research shows that dopamine
facilitates and serotonin inhibits sex in male rats. She noted that studies
in humans show that drugs that affect serotonin levels also affect sexual
function. ''Anti-depressants like Prozac or Zoloft cause a decrease in
libido and the ability to have orgasms,'' Hull pointed out. ''It's a side
effect of serotonin.''
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- Dr. Sara Leibowitz of the Rockefeller University studied
the effect of the peptide galanin on fat intake. ``There is a positive
feedback loop,'' she said. ``Galanin shifts our preference to more fat
intake. A high-fat diet in turn stimulates galanin release.''
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- ``If we found a small molecule to bind the galanin active
site, then we could reduce fat intake,'' Leibowitz added. ``In women at
puberty, a high-fat diet stimulates estrogen and progesterone production.
These steroids in turn stimulate galanin release, which then stimulate
more steroids.''
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- Understanding the similarities and the differences involved
in the pathways of the brain that control eating, mating and drug taking
will help in the development of therapies aimed at treating different types
of addiction, the panel concluded.
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