Goldfish on Prozac

by Tyler Shendruk

Published: 9/15/10

The problem
WHEN YOU THINK of pollution, what jumps to mind? Heavy metals, BP oil spill, carbon tax? What about the words antibiotics, the pill, nicotine, or Prozac? These so-called pharmaceutical pollutants are seeping out of our medicine cabinets and into our rivers and lakes.
Drugs are only partially metabolized in your body; the rest of them are flushed down the toilet. To make matters worse, traditional sewage treatment plants fail to cleanse the water of these chemicals, allowing them to flow right into rivers and lakes.
Last year Canadians filled 483 million prescriptions (that’s 14 prescriptions per person and doesn’t count the large amounts of antibiotics given to livestock).
So what happens when all the fish in the pond are on Prozac?

The researcher
Vance Trudeau is a neuroendocrinologist at the U of O and the Centre for Advanced Research in Environmental Genomics. He studies how hormones control brain function and how, in turn, the brain regulates sexual development.

The project
Fluoxetine, the trade name for Prozac, can be found in the brain and liver tissues in wild fish, and, just like in people, increases fishes’ serotonin levels. To understand how the drug upsets sex hormone levels in wild fish populations, Trudeau studies normal goldfish whose food intake, seasonal growth rates, and reproduction have been previously well studied.

The key
When Trudeau’s research group studied female goldfish injected with flouxetine, they found that multiple genes in the brain were affected, causing a decrease in estrogen levels in the blood. Some of these genes are known to have an impact on the reproductive and social behavior of fish. To make matters worse, fluoxetine has an impact on the secretion of growth hormones, causing the fish to feed less and to become underweight.
To simulate the levels of Prozac detected in the environment, another test was done where fluoxetine was added directly to the tanks of male goldfish. Trudeau’s team then added potent female sex pheromones to the water. This should have stimulated the healthy, normal males to release their sperm and fertilize the eggs. However, male goldfish that had been exposed to the fluoxetine completely fail to release their sperm.
Poor goldfish.