A molecule that inhibits a neurotransmitter receptor reverses many of the symptoms in a mouse model of fragile X syndrome, the most common form of inherited mental retardation. The disorder is caused by mutations in the FMR1 gene that result in overactivity of the mGlu5 receptor.

Lothar Lindemann at F. Hoffmann-La Roche in Basel, Switzerland, Mark Bear at the Massachusetts Institute of Technology in Cambridge and their colleagues treated young adult mice engineered to have fragile X syndrome with a new long-acting mGlu5 inhibitor, CTEP, for up to four months. The treatment reversed a range of defects, including hyperactivity, impaired learning and memory, and abnormal neuronal shape. CTEP also corrected the elevated rate of protein synthesis in the brain's hippocampal region, which is characteristic of the disease.

Several drug companies are testing mGlu5 inhibitors in clinical trials.

Neuron 74, 49–56 (2012)