Date of Award

12-2014

Degree Name

Doctor of Philosophy

Department

Psychology

First Advisor

Dr. Lisa E. Baker

Second Advisor

Dr. Cynthia Pietras

Third Advisor

Dr. Alan Poling

Fourth Advisor

Dr. Charles Ide

Keywords

Atrazine, behavior, toxicology, motor coordination, dopamine, striatum

Abstract

The adverse health risks of exposure to the herbicide, atrazine, in humans are not fully understood. Although numerous studies have demonstrated atrazine to be an endocrine disrupter, the neurobehavioral consequences of atrazine exposure have not been thoroughly examined. The aim of this study was to investigate the effects of environmentally-relevant levels

of gestational followed by continued chronic atrazine exposure on motor function, learning and memory, anxiety, and striatal dopamine content in rodents. Pregnant Sprague Dawley rats were treated by gavage with 100 µg/kg atrazine (ATZ low), 10 me/kg atrazine (ATZ high), or vehicle on

gestational day l through postnatal day (PND) 21 (weaning). Upon weaning, offspring continued daily vehicle or atrazine gavage treatments for an additional six months. Rats were subjected to a series of behavioral assays, including locomotor activity assessments, a walking beam task, an operant spatial discrimination reversal task, a Morris Water Maze task, and a light-dark box test. Twenty-four hours after the last treatment, animals were euthanized, and tissue samples from the striatum, nucleus accumbens, and median eminence were analyzed for dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC). Results revealed ATZ low males

displayed increased locomotor activity at 1 month of age, while ATZ high males displayed decreased locomotor activity at 6 and 7 months of age. Both ATZ low and ATZ high males and females had impairments in walking beam performance on PND 37-46 and at 22 weeks of age. No differences were observed in learning and memory while ATZ high males had increased anxiety-like behavior at 7 months of age. Neurochemical assays revealed decreased striatal DA and DOPAC in ATZ high males and females and in ATZ low males. ATZ low females had decreased striatal Dn and increased DA turnover. These results suggest environmentally relevant exposures to atrazine have the potential to disrupt brain regions and behaviors associated with motor functioning. Further investigation of the potential impact of atrazine exposure on neurological development in humans and increased risk for Parkinson disease may be warranted.

Access Setting

Dissertation-Open Access

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