Tadpole experiment shows drug may cause autism

Providence, RI – Brown University recently published a study in the Journal of Neuroscience that links autism’s cause to the epilepsy drug valporic acid (VPA) taken during pregnancy.

“We can use this to identify biological targets that we can potentially manipulate to effect a rescue,”

Lead study author and Brown University graduate student Eric James told Medical Xpress.

“We can use this to potentially identify the mechanism by which valporic acid causes neurodevelopmental disorders.”

The study was conducted by Carlos Aizenman, an associate professor of neuroscience at Brown whose team raised tadpoles. During the tadpoles development of the optic tectum, a crucial part of their brains, VPA was injected into half of the population. The other half were left alone to develop normally as a control group.

The team then compared the two groups in how they swam together, avoided collisions, and handled loud noises. What they found was astonishing. The VPA group didn’t swim well with others, failed to avoid the projected images at the bottom of their petri dishes, and didn’t get used to startling noises. They also experienced short but frequent seizures, something often shown to go hand-in-hand with autism.

In addition to these factors the team also found that the VPA tadpoles also had malformed optic tectums. Usually neurons in optic tectums form treelike structures called axons and dendrites. As these grow “branches” are appropriately trimmed, but with brains exposed to the drug, there is no trimming with branches growing widely.

“That’s what you see in an immature brain across different species and different experiments,” James told Medical Xpress. “That goes along with this idea of neurodevelopmental disorders where there is a lack of pruning.”

Eric James will continue to study the effects of VPA.

Contributed by Audrey L. Hollingshead

Source: Medical Xpress website: Tadpole model links drug exposure to autism-like effects