Auditory Dysfunction in Fragile X Syndrome in a Mouse Model of Fragile X

Elizabeth MCullough and Achim Klug

With a $90,000 grant from FRAXA, Dr. McCullagh and Dr. Achem Klug at the University of Colorado investigated whether auditory neural circuits are altered in Fragile X mice. They saw minor differences in these mice compared to B6 (control) mice in several measures of auditory acuity. Fmr1 mice had increased latency to the startle response for almost all conditions compared to B6 mice, suggesting altered timing to acoustic cues. These experiments show that, consistent with patient reports and anatomical/physiological data, the auditory system is altered in a mouse model of FXS, though with some potential compensation leading to a subtle behavioral impact.

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GABAergic Inhibitory Function in Fragile X Syndrome

With a $100,000 grant from FRAXA Research Foundation, Drs. Joshua Corbin and Molly Huntsman from the Children’s National Medical Center examined the role of a particular class of brain cells (inhibitory interneurons) that dampen excessive activity in the “emotional center of the brain” (the amydala). This inhibition is deficient in Fragile X, and so they are looking for ways to remedy this. This is particularly interesting to parents of children who are overly anxious and emotional. They worked with Dr. Walter Kaufmann, a clinician at Kennedy Krieger Institute in Maryland.

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The miRNA Pathway in Fragile X Syndrome

With a $120,000 grant from FRAXA Research Foundation over 2008-2009, Drs. Oostra and deVrij at Erasmus University studied miRNA and Fragile X. miRNAs are RNAs that can repress the translation of target mRNAs – therefore they can play a role in protein synthesis within the neuron. Preliminary results showed large differences in miRNA expression in the Fragile X mouse brain compared to the wild type. This lab investigated the effect of mGluR5 antagonists on the levels of these specific miRNAs.

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