Date of Award

Spring 5-2013

Degree Type

Honors College Thesis

Department

Psychology

First Advisor

David Echevarria

Advisor Department

Psychology

Abstract

Stress affects how we function in all aspects of our lives. It is our physiological response to a threat. In fact, its origins were very adaptive. Stress can cause an animal to flee a predator and avoid being eaten. In today’s society, stress can prompt us to work harder to achieve a good education or promotion at work so that we can afford food, shelter, and entertainment. But stress can also impair performance at work, on tests, and even can cause long-term bodily harm. In order to fully understand the deleterious effects of stress and thereby properly treat it, it is useful to better understand the accompanying changes in behavior. This experiment is designed to evaluate the effects of an acute stressor’s ability to induce behavioral changes indicative of the stress response in zebrafish. This experiment will measure the baselines of three paradigms, and subsequently assess any behavioral changes that are the result of acute exposure to a novel stressor.

Zebrafish are an up and coming model organism, but there are many unknowns in the literature about their behavior. Since the 1980s, the use of the zebrafish as an animal model in neuroscience research has steadily increased.

The three paradigms reported here are open field, light/dark discrimination, and novel tank dive. Stable performance baselines will serve as control measurements and should replicate what has been reported in the literature. The treatment condition (for all three experiments) will consist of a 15-minute pretest exposure to an acute stressor.

The acute stressor, known as a “beaker stressor”, places the fish in a 250 ml beaker containing 100 ml of water, away from its companions. The effects of confinement and isolation have been shown to increase the production and release of cortisol, a stress hormone (Speedie & Gerlai, 2007, Champagne, Hoefnagels, Kloet & Richardson, 2010). Once the zebrafish have been exposed to the stressor for 15 minutes, they will be placed in one of three apparatuses to assess any associated behavior change.

Since zebrafish have a hypothalamic-pituitary-interrenal (HPI) axis similar to the HPA axis in humans, they are ideal experimental subjects for this area of research (Champagne, et al., 2010). Previous studies report that the activation of the HPI and HPA result in a biochemical cascade (Barton, 2002, Tsigos, 2002). Cortisol is one of the chemical messengers released during this cascade, a chemical associated with the physiological components of stress (Champagne, et al., 2010). This study should provide more information for human comparisons of reactions to stress as well as expand what we know about the zebrafish model.

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