Posted June 6, 2012
A team of Idaho State University researchers have discovered that fish show autism-like gene expression after exposure to water containing psychoactive pharmaceuticals, according to research published June 6 in the open access journal PLoS ONE.
The results may suggest an environmental trigger for autism, although this finding may only apply to genetically predisposed individuals.
"The psychoactive pharmaceuticals were tested at concentrations similar to those found in aquatic systems," said Michael Thomas, ISU associate professor of biological sciences and the lead researcher in the project. "This discovery implies that these drugs might be involved in the increase in autism in the past 30 years."
Thomas said that although these findings are significant, it is too early to draw firm conclusions about the study.
"We've really proposed a new question, but not any new answers," he said. "But asking a new question is the first step towards learning something new, and in many ways, it's the most important step. It is our hope that this new question will useful for the autism research community, and eventually lead to fruitful new answers. It is important to remember that much more research on this topic is needed – it's not time to draw any conclusions, yet."
The team discovered that certain psychoactive pharmaceuticals induced gene expression patterns in a fish model that mimic expression patterns in humans with autism. The gene expression patterns are associated with neurological development and growth.
The fish exposed to pharmaceuticals also displayed behavioral characteristics that indicate anxiety-like symptoms. This shows that gene expression induced by drugs had a broader impact on the fish.
The drugs studied include an anti-seizure drug carbamazepine and two anti-depression drugs, fluoxetine and venlafaxine. These represent some of the most frequently prescribed pharmaceuticals. The introduction of fluoxetine and venlafaxine correspond to periods of rapid increase in the prevalence of autism, Thomas said.
This raises the possibility that pregnant women who drink water containing trace concentrations of these drugs will pass them along to the fetus, according to Thomas. The fetus has a leaky blood-brain-barrier, which allows drugs to pass directly into the developing brain.
"The drugs affect activity of serotonin and other neurotransmitters, which are important in the development of neurological networks and, basically, affect how the brain is wired," Thomas said.
Again, Thomas emphasized that his study is early-stage work and more study is needed – at this time there is no reason for pregnant women to be concerned about results of the study.
The journal PLoS ONE is published by the Public Library of Science and is among the top tier of research journals and is noted for publishing work that is both cutting-edge and potentially transformative. This study can be viewed online at http://dx.plos.org/10.1371/journal.pone.0032917.
The ISU research team involved with this project included Loubin Yang, biological sciences research assistant professor, and ISU graduate students Parag Joshi, Victor Ezike and Gauray Kaushik. For the project, Thomas also collaborated with Rebecca Klaper at the University of Wisconsin – Milwaukee School for Freshwater Sciences.
The title of the study is "Psychoactive pharmaceuticals induce fish gene expression profiles associated with human idiopathic autism."
"This project is an exciting contribution to the biomedical sciences from Idaho State University, and creates interesting opportunities for students to become involved in cutting-edge research in ways that are not possible at larger institutions," Yang said.
Richard Jacobsen, ISU executive director for the Office of Research and Technology Transfer commented on team's research.
"This is great research because if focuses on the potential effects of pharmaceuticals in drinking water and the results may be useful for additional applications beyond fish," Jacobsen said. "It is also an excellent example of cooperative research with other universities, in particular, the University of Wisconsin – Milwaukee's School of Freshwater Sciences.