Researchers identify drugs that reverse cause of autism  

New York, March 10: A new method of screening fruit flies has helped researchers identify several drugs and small molecules that reverse the features of fragile X (FX) syndrome - a leading cause of autism.

'Our discovery of glutamate toxicity in the Drosophila (fruit flies) model of FX syndrome allowed us to develop this new screen for potential drug targets,' said lead researcher Stephen Warren of Emory University, Atlanta.

Findings of the study have been published in the online edition of the journal Nature Chemical Biology.

'We believe this is the first chemical genetic screen for FX syndrome, and it highlights the general potential of Drosophila screens for drug development,' Warren said.

Autism is caused by the functional loss of the FX mental retardation protein (FMRP). There is no known drug therapy for the FX syndrome.

Scientists believe FMRP affects learning and memory through regulation of protein synthesis at synapses in the brain.

One of the leading views, proposed by Warren and colleagues, suggests that over-stimulation of neurons by neurotransmitter glutamate is partly responsible for brain dysfunction resulting from the loss of FMRP.

In their current experiment, Emory scientists used a Drosophila model lacking the FMR1 gene. These fruit flies have abnormalities in brain architecture and behaviour that parallel abnormalities in the human form of fragile X syndrome.

When FMR1-deficient fly embryos were fed food rich in glutamate, they died during development, which is consistent with the theory that the loss of FMR1 results in excess glutamate signalling.

The scientists placed the FMR1-deficient fly embryos in thousands of tiny wells containing food with glutamate. In addition, each well contained one compound from a library of 2,000 drugs and small molecules. Using this screening method, the scientists uncovered nine molecules that reversed the lethal effects of glutamate.

'Most importantly, it identifies several small molecules that significantly reverse multiple abnormal characteristics of FMR1 deficiency. These findings open the door to development of effective new therapies for fragile X syndrome,' said Warren.