Next-Generation Treatments for Fragile X Syndrome

Findings from a new study in Biological Psychiatry

Philadelphia, PA, November 29, 2012 – A potential new therapeutic strategy for treating Fragile X syndrome is detailed in a new report appearing in the current issue of Biological Psychiatry, from researchers led by Dr. Lucia Ciranna at University of Catania in Italy.

Fragile X syndrome (FXS), the most common heritable form of autism and intellectual disability, is one of the most exciting areas in brain research at the moment.

A decade ago, Dr. Mark Bear and his colleagues discovered that an animal model for FXS was associated with a distinctive alteration in brain function, enhanced long-term depression, which was mediated by a specific mechanism, enhanced signaling via the metabotropic glutamate receptor 5 (mGluR5). Dr. Bear and his colleagues proceeded to show that blocking mGluR5 showed promise in animal models as the first treatment for FXS. A recent preliminary study of the drug fenobam, an mGluR5 blocker, provided hints of some beneficial effects in adults with FXS.

mGluR5 blockers are likely to be the first examples of several therapeutic mechanisms that will emerge in upcoming years. Now, Ciranna and colleagues have identified another potential therapeutic mechanism for FXS.

Using a mouse model of FXS, they demonstrate that blockade of the serotonin 7 (5-HT7) receptor, like mGluR5 blockade, reduces long-term depression mediated by mGlu receptors. In neuroscience, long-term depression is the term used to describe a reduction or decrease in the effectiveness of neuronal synapses, meaning that the ability of nerve cells to communicate is diminished.

The effect that they detected occurred in the hippocampus, one of the brain structures most crucially involved in learning and memory.

“This result opens new perspectives in the therapy of Fragile X Syndrome, suggesting that selective agonists for 5-HT7 receptors might become useful pharmacological tools,” said Ciranna.

This led them to study the effects of LP-211, a new compound with a high affinity and selectivity for 5-HT7 receptors. The data showed that LP-211 behaves as an agonist of 5-HT7 receptors and therefore, may be used as a potential treatment for Fragile X syndrome, although much more work would be necessary before it could be tested in humans.

“This study illustrates a critical issue in the development of new treatments for psychiatric disorders. It is uncommon that all patients with a particular disorder will tolerate or respond to a single treatment. Thus, we need multiple approaches to treatment,” commented Dr. John Krystal, Editor of Biological Psychiatry. “Further, this study illustrates how a single insight into the biology of an illness, in this case enhanced mGluR5 signaling, yields multiple novel mechanisms that might be explored to develop novel treatments.”

The article is “Activation of 5-HT7 Serotonin Receptors Reverses Metabotropic Glutamate Receptor-Mediated Synaptic Plasticity in Wild-Type and Fmr1 Knockout Mice, a Model of Fragile X Syndrome” by Lara Costa, Michela Spatuzza, Simona D'Antoni, Carmela M. Bonaccorso, Chiara Trovato, Sebastiano A. Musumeci, Marcello Leopoldo, Enza Lacivita, Maria V. Catania, and Lucia Ciranna (doi: 10.1016/j.biopsych.2012.06.008). The article appears in Biological Psychiatry, Volume 72, Issue 11 (December 1, 2012), published by Elsevier.

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Notes for editors
Full text of the article is available to credentialed journalists upon request; contact Rhiannon Bugno at +1 214 648 0880 or Biol.Psych@utsouthwestern.edu. Journalists wishing to interview the authors may contact Lucia Ciranna at +39 095 738 4111 or ciranna@unict.it.

The authors’ affiliations, and disclosures of financial and conflicts of interests are available in the article.

John H. Krystal, M.D., is Chairman of the Department of Psychiatry at the Yale University School of Medicine and a research psychiatrist at the VA Connecticut Healthcare System. His disclosures of financial and conflicts of interests are available here.

About Biological Psychiatry
Biological Psychiatry is the official journal of the Society of Biological Psychiatry, whose purpose is to promote excellence in scientific research and education in fields that investigate the nature, causes, mechanisms and treatments of disorders of thought, emotion, or behavior. In accord with this mission, this peer-reviewed, rapid-publication, international journal publishes both basic and clinical contributions from all disciplines and research areas relevant to the pathophysiology and treatment of major psychiatric disorders.

The journal publishes novel results of original research which represent an important new lead or significant impact on the field, particularly those addressing genetic and environmental risk factors, neural circuitry and neurochemistry, and important new therapeutic approaches. Reviews and commentaries that focus on topics of current research and interest are also encouraged.

Biological Psychiatry is one of the most selective and highly cited journals in the field of psychiatric neuroscience. It is ranked 5th out of 129 Psychiatry titles and 16th out of 243 Neurosciences titles in the Journal Citations Reports® published by Thomson Reuters. The 2011 Impact Factor score for Biological Psychiatry is 8.283.

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