THIS IS YOUR BRAIN ON DRUGS... AND SEX AND FOOD

BRECKENRIDGE, CO, Jan 27 (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.''

``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.''

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%.

``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.''

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.

``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.

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.''

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.''

``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.''

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.