Date of Award

Spring 5-1-2025

Document Type

Honors Project

Degree Name

Bachelor of Science

Department

Biological Sciences

Department Chair or Program Director

Baker, Dianne

First Advisor

Baker, Dianne

Second Advisor

Waters, Robert Parrish

Third Advisor

O'Dell, Deborah

Major or Concentration

Biology

Abstract

Per- and polyfluoroalkyl substances (PFAS) are a group of environmental contaminants that cause disruptions to the nervous and endocrine systems. Perfluorooctanesulfonate (PFOS) is considered one of the most disruptive PFAS to the nervous system, and may disrupt neurodevelopment of the dopaminergic system, which has been linked to neurodevelopmental disorders like Attention Deficit/Hyperactivity Disorder (ADHD) in humans. I hypothesized that early life PFOS exposure disrupts the development of the dopaminergic system. To test this hypothesis, I exposed zebrafish to 0.05, 0.5, and 5.0 mg/L PFOS through 5 days of embryonic and larval development. To assess acute effects of PFOS on the dopaminergic system, I measured transcript levels of genes that are crucial to the transport, synthesis, degradation, and signaling of dopamine in samples collected at 5 days post-fertilization. To test for long-term effects of PFOS exposure, treated fish were transferred to system water and reared until 60 days post-fertilization. I then dissected their brains and performed a gene expression analysis. The highest concentration of PFOS (5 mg/L) significantly upregulated tyrosine hydroxylase, the gene encoding the rate limiting enzyme of dopamine synthesis, in samples collected at 5 days post fertilization (p < 0.001). These data suggest that PFOS acutely disrupts the dopaminergic system.

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