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Lab Notes: Diets Sabotaged in the Brain
By MedPage Today Staff
Published: June 24, 2011



Battle of the Bulge Rages in the Brain

Concerted, but unsuccessful, efforts to lose weight might indicate that
the brain has thrown up a neurochemical roadblock, according to a study
involving obese mice.

After a 24-hour fast, lean mice lost 18% of their body weight, whereas
their roly-poly counterparts lost only 5%. Laboratory studies showed
that the obese animals did not exhibit downregulation of genes that
activate the interleukin-1 system and associated anti-inflammatory
cytokines, as reported in Obesity.

"Our data show that fasting induces an anti-inflammatory effect on a
lean animal's neuroimmune system, and that effect is inhibited by a
high-fat diet," Gregory G. Freund, MD, of the University of Illinois in
Urbana, said in a statement. "Some of the brain-based chemical changes
that occur in a lean animal simply don't occur in an obese animal."

On the basis of the findings, Freund cautioned against beginning a
weight-loss effort with a fast or "cleansing day," as that may trigger
alterations in the immune system preventing weight loss.

Investigators also found that fasting adversely affected obese animals'
activity level and behavior. As compared with lean animals, the fat ones
moved around less, had altered burrowing activity, and generally
exhibited signs of anxiety and depression, possibly reflecting another
alteration in brain chemistry and providing another reason for caution
about beginning weight loss with a fast.

-- C.B.



Atkins Diet for Alzheimer's?

In the 1920s, the ketogenic diet was a popular way to relieve epileptic
seizures. While drugs have mostly replaced the therapeutic diet, it is
still used for those refractory to drugs. Now, researchers say they've
figured out why it works and also how it may help in neurodegenerative
diseases.

According to a report in the July issue of the Journal of Clinical
Investigation, mouse experiments showed that the diet increased
activation of adenosine A1 receptors, which helped to suppress seizures.

Previous research had suggested the diet could be beneficial in other
neurodegenerative disorders including Alzheimer's disease and
Parkinson's disease.

"There is evidence that adenosine deficiency might also be a
pathological hallmark of Alzheimer's. Adenosine deficiency can lead to
both seizures [and] cognitive impairment," senior author Detlev Boison,
PhD, of the Legacy Research Institute in Portland, Ore., told MedPage Today.

"Interestingly, seizures are a comorbidity of Alzheimer's and cognitive
deficiency is a comorbidity of epilepsy. Based on this rationale and the
fact that a ketogenic diet augments adenosine signaling in the brain, a
ketogenic diet should be effective in Alzheimer's disease as well," said
Boison.

-- C.K.