mGluR5 Spells Hope For Autism

Mark Bear, director of the Picower Institute and Picower Professor of Neuroscience (right), and Gül Dölen, a graduate student at Brown University,
report the correction of fragile X syndrome in mice. Photo / Donna Coveney

MIT News

Parents of autistic children have been preyed upon by purveyors of unproven treatments for their children's autism. But today there is hope, real hope, for autistic persons and the family members who care about their autistic children. Hope for an effective medical autism treatment is no longer something peddled by charlatans. We can now see it. We can even spell it. Hope for autism is spelled mGluR5.

mGluR5 is the shorthand for a metabotropic glutamate receptor. It was featured in the study led by Mark F. Bear, director of the Picower Institute and Picower Professor of Neuroscience at MIT published in the December 20 2007 edition of Neuron. The study by Professor's Bear's team supports the theory that many of FXS's (Fragile X's) psychiatric and neurological symptoms--learning disabilities, autistic behavior, childhood epilepsy--stem from too much activation of one of the brain's chief network managers, the metabotropic glutamate receptor mGluR5. As reported in MIT News:

Bear and colleagues study how genes and environment interact to refine connections in the brain. Synapses are the brain's connectors and their modifications are the basis for all learning and memory. There's a growing consensus among researchers that developmental brain disorders such as FXS, autism and schizophrenia should be considered "synapsopathies"--diseases of synaptic development and plasticity (the ability to change in response to experience).

Dendritic spines--little nubs on neurons' branchlike projections--receive many of the synaptic inputs from other neurons. Abnormal spines have long been associated with various forms of human mental retardation. In FXS, spines are more numerous, longer and more spindly than they should be. Thin spines tend to form weak connections.

The research team found that a 50 percent reduction in mGluR5 fixed multiple defects in the fragile X mice. In addition to correcting dendritic spines, reduced mGluR5 improved altered brain development and memory, restored normal body growth and reduced seizures--many of the symptoms experienced by humans with FXS.

The researchers used genetic engineering to reduce mGluR5, but a drug could accomplish the same thing. Although not yet approved by the FDA, mGluR5 blockers are entering into human clinical trials. "Insights gained by this study suggest novel therapeutic approaches, not only for fragile X but also for autism and mental retardation of unknown origin," Bear said.

As Christmas approaches families with autistic children may already have received our most wondrous gift of all - the knowledge necessary to provide an effective medical treatment for autism.

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