Author ORCID Identifier

https://orcid.org/0000-0002-6648-2757

Date Available

7-17-2023

Year of Publication

2023

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Arts and Sciences

Department/School/Program

Psychology

First Advisor

Dr. Joshua Beckmann

Abstract

Globally, food addiction (FA) is a growing area of research and is largely attributed to the availability of foods that are both energy dense and high in fats and sugars. Further, it has been suggested, that sugar and fat, when consumed frequently, have properties similar to drugs of abuse. While the validity of FA is questioned, researchers have drawn parallels between substance use disorder (SUD) and FA. For example, sugar binge models emphasize craving, withdrawal and binging as primary components of FA, which are also hallmarks of SUD. Additionally, both natural rewards, like sugars, and drug rewards act on the dopamine (DA) system, which is implicated in SUD. Currently, research on FA has largely focused on demonstrating the similarities between FA and SUD, but few studies have assessed preclinical decision-making processes when animals are exposed to extended sugar access. Substance abuse research has highlighted the importance of including non-drug alternatives to mimic real-world scenarios in which many competing alternatives are available, but similar experiments have not been implemented for FA. The current experiment implemented a controlled reinforcement ratio (CRR) task in which rats were presented with the choice between fructose and another non-drug alternative, intracranial self-stimulation (ICSS), to assess choice behavior following a fructose self-administration paradigm. Additionally, the use of ICSS in this manner challenges the rate-dependent threshold procedure that currently dominates the literature. Baseline measures of exchange rate for both fructose and saccharin as well as measures for fructose and ICSS threshold were compared to measures following fructose self-administration. Rats were assigned to a short-access (1-hr) fructose condition or long-access (6-hr) fructose condition. While 6-hr rats did not show escalation of intake, results showed that both groups exhibited a decrease in demand intensity for fructose and an increase for ICSS following fructose self-administration. Additionally, the 6-hr group exhibited an increase in ICSS demand elasticity following self-administration, but the same was not noted for the 1-hr group. Finally, a global parameter for both fructose and saccharin exchange rate provided the best model fit for these data meaning there was no difference between pre- and post- self-administration or between access groups. These results provide support for relative value theory and highlight the importance of using concurrent choice models as opposed to single schedule models when conducting SUD and FA studies.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2023.288

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