Thesis Format

Integrated Article

Sex Differences in Sucrose Sensitization

Author

Vangel Matic, Western UniversityFollow

Degree

Master of Science

Program

Neuroscience

Supervisor

Ossenkopp, Klaus-Peter

2nd Supervisor

Kavaliers, Martin

Co-Supervisor

Abstract

Women have a greater prevalence of eating-related disorders than men and are thought to experience stronger cravings for sweet foods. In rodents, female-biased sex differences have been identified in the preference and motivation for highly palatable sweet foods. Investigations using a paradigm of locomotor sensitization – a behavioural index of addiction-related neuroadaptations – have mainly focused on male subjects in the evaluation of highly palatable sweet foods. The present thesis explored sex differences and context- related effects of sucrose sensitization (0.3 M) and cross-sensitization with the D2/D3 agonist, quinpirole (0.5 mg/kg). Sucrose sensitization was identified in adult female rats but not adult male rats. Pre-exposure to sucrose enhanced quinpirole sensitization in both female and male rats. In female rats, context-related enhancements of sensitization were observed for quinpirole sensitization but not sucrose sensitization. Future investigations of sucrose sensitization should explore dose-related effects, concurrent cross-sensitization paradigms, water-restriction confounds, and context-pairing consistency.

Summary for Lay Audience

Highly palatable foods like sugar and fat activate the same brain pathway as addictive drugs – the mesolimbic dopamine pathway. Drug-induced activation of this pathway is thought to be involved in the experience of drug craving in addiction. While ‘food addiction’ is not currently considered a mental health disorder like drug addiction, the similarities between highly palatable foods and addictive drugs has led to certain foods being considered addictive. Compared to men, women have been found to have a greater prevalence of eating- related disorders and preference for sweet foods and experience more intense food cravings. Similarly, in animal models, female rats show a greater preference for and motivation to obtain sweet solutions than do males – suggesting that sex differences in sweet food preferences and cravings in humans may be biologically-based. An experimental paradigm for investigating drug-related craving in animals is locomotor sensitization – drug-induced activation of the mesolimbic dopamine pathway is thought to underlie the increase in locomotor activity that occurs with repeated drug administration. Highly palatable foods have been shown to enhance the effect of drug-induced sensitization, however sex differences in this effect have not been evaluated. The first experiment of the present thesis evaluated sex differences in the effect of locomotor sensitization induced by sucrose (table sugar) and its enhancement of sensitization induced by a dopaminergic agonist similar to common drugs of abuse. It was found that females displayed a greater effect of sucrose sensitization than males, suggesting that a sex difference may exist in the response of the mesolimbic pathway to highly palatable foods and perhaps underlie the sex differences observed in humans. The second experiment of the thesis explored the role of the drug administration environment in moderating sucrose sensitization in female rats. The results of the second experiment did not reproduce the same findings as the first experiment and showed a relatively weak environmental moderation of sensitization which may be attributable to specific elements of the experimental procedure. Together, the present thesis contributed to a better understanding of the interaction of highly palatable foods and addictive drugs and described sex differences therein.

Recommended Citation

Matic, Vangel, "Sex Differences in Sucrose Sensitization" (2024). Electronic Thesis and Dissertation Repository. 10243.
https://ir.lib.uwo.ca/etd/10243

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