Honors Theses
Date of Award
Spring 5-9-2024
Document Type
Undergraduate Thesis
Department
Biomolecular Sciences
First Advisor
Gregg Roman
Second Advisor
Nicole Ashpole
Third Advisor
Bradley Jones
Relational Format
Dissertation/Thesis
Abstract
Functional alcohol tolerance is an adaptation made by the nervous system to high doses of alcohol, and is seen by a significant reduction in sensitivity to this drug. This tolerance is a significant contributing factor in the progression to Alcohol Use Disorders. A major goal of alcohol research is to understand how alcohol induces this tolerance. Dunc13 is a presynaptic active zone protein essential in synaptic vesicle docking and priming. Alcohol binds to the C1 domain of Dunc13 at physiological concentrations, which inhibits Dunc13 from binding Diacylglycerol. This inhibition is predicted to reduce Dunc13 activity and presynaptic activity. Yet, genetically reducing Dunc13 activity results in a tolerant-like state, including reduced behavioral and synaptic sensitivity to alcohol and increased alcohol self-administration. Our overarching hypothesis is that alcohol binding to Dunc13 inhibits synaptic activity, triggering tolerance formation. The goal of this thesis is to investigate the roles specific Dunc13 isoforms have in affecting the behavioral sensitivity to alcohol. Dunc13 has two principle isoforms, Dunc13A & Dunc13B, which are distinct in active zone localization and function. The independent roles these isoforms play in alcohol sensitivity, however, are not well understood. We used isoform-specific mutants and RNAi to reduce mRNA levels to explore the specific role of each isoform in ethanol sensitivity and sedation. We then used the FlyBar assay to expose them to a vapor of 50% ethanol and measured the time for 50% to appear sedated. When compared to control genotypes for resistance to the sedative effects of alcohol, Dunc13A-Null mutants showed an increase in sensitivity, while Dunc13B-Null mutants did not show a significant difference. When Dunc13B expression was reduced using RNAi, however, we observed a significant decrease in sensitivity. These results suggest that the two Dunc13 isoforms have distinct functions in the behavioral responsiveness to alcohol. In the future, we will study the effects of each isoform, and their genetic interactions, on the formation of tolerance and increased alcohol self-administration in Drosophila.
Recommended Citation
Havard, Makenzie, "Role of Dunc-13 Isoforms in Alcohol Sensitivity in Drosophila" (2024). Honors Theses. 3129.
https://egrove.olemiss.edu/hon_thesis/3129
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