http://today.reuters.com/news/articl...1-ArticlePage2

Puzzle of antipsychotic drug weight gain solved
By Will Dunham


WASHINGTON (Reuters) - Researchers said on Monday they have pinpointed the reason some drugs used to treat mental illnesses like schizophrenia cause patients to gain a lot of weight, raising hope for developing drugs without this side effect.

Antipsychotic medications such as Zyprexa, made by Eli Lilly and Co., increase the activity of an enzyme called AMPK in cells in the part of the brain that regulates eating behavior, according to research in mice led by scientists at Johns Hopkins University in Baltimore.

"It's a big increase and it occurs with very little doses of the drug," Dr. Solomon Snyder, professor of neuroscience at Johns Hopkins School of Medicine, said in an interview.

The study was published in the Proceedings of the National Academy of Sciences.

.......

"Unfortunately, Zyprexa, which everybody agrees is the best therapeutic agent, gives the worst weight gain, along with clozapine, the parent drug in the class. And it was sort of a puzzle," Snyder added.

The researchers also showed that AMPK's increase was because the antipsychotic drugs were interfering with the important protein histamine, which is involved in allergy symptoms and long has been suspected for a role in weight control.

Snyder said the findings point to the possibility of developing a new generation of antipsychotic drugs that are effective but do not cause weight gain.