Fish exposed to SSRIs exhibit abnormal behavior, study finds

March 6, 2012

Fish exhibit abnormal behavior and lower levels of anxiety when exposed to Selective Serotonin Reuptake Inhibitors (SSRI), which are common drugs used to treat depression, among other disorders. The study, by Baylor University researchers and online in the journal Environmental Science & Technology, also found that human data for drug activity can be used to predict surface water concentrations of these substances that negatively impact fish behavior.

The Baylor research, which builds on their previous study of pharmaceuticals found in downstream of a wastewater treatment plant, has implications not only for the environment but for communities planning to begin wastewater reuse programs.

"This research is an important step in determining the long-term consequences of drugs taken up by fish in the environment and has direct implications for both survival and fitness of fish," said Bryan Brooks, Ph.D., professor of and biomedical studies and director of environmental health science in Baylor's College of Arts & Sciences. He and former Baylor student Theodore W. Valenti, Jr., Ph.D., now a National Research Council post-doctoral fellow with the Environmental Protection Agency in Duluth, Minn., co-authored the article as part of Valenti's dissertation research.

"This helps our understanding of the potential impact of pharmaceuticals in the environment which are accumulating in fish," Brooks said.

In the current study, the shelter-seeking behavior of fathead minnows was monitored under laboratory conditions for 28 days using digital tracking software to diagnose while they were exposed to the SSRI sertraline, which is used to treat , panic attacks and other disorders. Sertraline concentrations and lighting conditions significantly affected the time that the minnows spent in a sheltered area.

During dark conditions, sertraline-exposed fish spent approximately 67 to 78 percent of the time that control fish spent in the shelter. During light intervals, fish exposed to sertraline spent between 18 and 42 percent less time in the shelters.

"The shelter was the only dark area during light conditions in the observation tanks; therefore, control fish apparently retreated to the shelter to reduce anxiety, whereas fish exposed to sertraline appeared to display reduced anxiety and did not exhibit this behavior," Brooks said.

"Based on our observations, we hypothesize that fish exposed to sertraline displayed reduced and consequently were more willing to explore outside of their shelters during both light and dark conditions. Fish willing to spend more time away from shelters face greater predation risk, and their overall survival rate may be reduced," he said.

Valenti noted that another very interesting aspect of the study was the accuracy of a quantitative model the Baylor researchers used to predict internal fish plasma concentrations when pH of the water was considered. These findings emphasize the importance of accounting for the pH of rivers and lakes during surface water quality assessments of pharmaceuticals and other weak acid and weak base contaminants.

"Improving our understanding of these relationships is paramount for reducing uncertainty during ecological risk assessments and is vital to addressing potential hazards associated with human population growth and urbanization in the future," Valenti said.

"Conservation and water reuse strategies will become paramount to meet water resource needs of future generations. Understanding emerging risks to water quality, from pharmaceuticals and other contaminants present at trace levels, is equally important to support responsible management decisions and meet environmental protection goals," Brooks added.

A previous study by Baylor researchers in the journal Environmental Toxicology and Chemistry, initially found residues of sertraline and fluoxetine, another SSRI, and their metabolites in three different types of fish living in the Pecan Creek in North Texas. A follow-up study by Baylor researchers in Pecan Creek, which appeared in the journal Analytical Chemistry, observed three additional human medications in fish. They were diphenhydramine, an over-the-counter antihistamine also commonly used as a sedative in non-prescription sleep aids and motion sickness; diltiazem, a for high blood pressure; and carbamazepine, a treatment for epilepsy and bipolar disorder.

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not rated yet Mar 06, 2012
That's a really happy-touchy-feely analysis of the results. How about looking at it like "we totally messed with the fear centre of the fish and caused them to take abnormal risks that would generally result in them being preyed upon and eaten in the wild".

Reminds me of studies that look into whether or not SSRIs and others cause suicidal and other violent behaviour.

Ah, sorry to rain on the parade.
1 / 5 (1) Mar 08, 2012
This reminds me of studies that propose visual input is responsible for dominance status in cichlids and sex changes in the blue wrasse that are much more clearly linked to chemosensory cues in the water (e.g., in a recent study from Russ Fernald's lab at Stanford). There is, of course, no animal model for how visual input would directly effect the required neuroendocrinological changes. And this work supports a model in which pheromones drive the changes associated with gonadotropin releasing hormone pulse frequency, which is also influenced by pharmaceuticals in waste water and other endocrine disruptors. Does anyone else perceive a need for the "right" model of how sensory input from the enviroment effects hormones that affect behavior. The visual model is not the "right" model in any species of vertebrate; there's no direct effect on gene activation!

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