Date Approved

5-7-2026

Graduate Degree Type

Thesis

Degree Name

Biomedical Sciences (M.H.S.)

Degree Program

Biomedical Sciences

First Advisor

Daniel Bergman, PhD

Second Advisor

Zeni Shabani, PhD

Third Advisor

David Kurjiaka, PhD

Academic Year

2025/2026

Abstract

Pharmaceuticals are increasingly recognized as contaminants of concern in aquatic ecosystems, often entering waterways due to incomplete removal by wastewater treatment plants. Despite frequent detection, the effects of these compounds on non-target, neurochemically sensitive organisms such as crayfish remains underexplored. Gabapentin, an anticonvulsant that binds to presynaptic voltage-gated calcium channels and reduces excitatory neurotransmitter release, is one such emerging contaminant. Given crayfish’s ecological importance and sensitivity to neuroactive substances, exposure to gabapentin may disrupt key behaviors such as locomotion. To place gabapentin’s effects in context, we also examined escitalopram (Lexapro), a selective serotonin reuptake inhibitor that elevates synaptic 5-HT, and carbamazepine (Tegretol), which primarily blocks voltage-gated sodium channels and modulates GABAergic transmission. Each alters neuronal excitability through distinct mechanisms, allowing for differential behavioral effects to be observed. We assessed locomotor behavior in a Y-maze under simulated current conditions by measuring time spent moving, both before and after injection with saline (control), gabapentin, escitalopram, or carbamazepine. Comparisons across treatments suggest drug-specific patterns of behavioral change. These findings offer insight into how commonly prescribed neuroactive pharmaceuticals may affect freshwater species and suggest that crayfish could serve as useful model for evaluating sublethal ecological impacts of aquatic pharmaceutical pollution.

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