uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Locomotor adaptation and elevated expression of reward-relevant genes following free-choice high-fat diet exposure
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Functional Pharmacology.
Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, University of Gothenburg, Addiction Biology Unit, Gothenburg.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Functional Pharmacology.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. (Neuropharmacology, Addiction and Behaviour)
Show others and affiliations
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Obesity may be induced in rodents by long-term access to dietary fat. Such treatment has been reported to have behavioural effects including reduced anxiety-like behaviour and diminished operant responding for psychostimulants. It is unclear whether such effects are secondary to metabolic changes due to excess body weight, or to the extended access to palatable food reward. The aim of this study was to investigate the effects of a short palatable diet exposure (10 days) on performance in the open field test of novelty-induced locomotion and anxiety-like behaviour in rats. We subjected rats to a free-choice high-fat or high-sugar diet, or both, for a period of 10 days. Increased caloric intake was observed in all groups but body weight at Day 10 did not differ from chow-fed controls. We report that consumption of the free-choice high-fat diets was associated with higher novelty-induced activity and reduced anxiety-like behaviour in the open field test. In addition, we used RT-PCR to show that the high-fat group had 39% higher expression of mu opioid receptor in the lateral hypothalamus, and that tyrosine hydroxylase expression was elevated more than two-fold in the ventral tegmental area of rats with access to both high-fat and high-sugar. In conclusion, these results show that subchronic exposure to a free-choice high-fat diet induces behavioural adaptations such as elevated locomotor activity and attenuated experimental anxiety. The changes observed in gene expression related to reward after high-fat diet exposure indicate that these behavioural adaptations are related to reward function.

National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-119489OAI: oai:DiVA.org:uu-119489DiVA: diva2:300940
Available from: 2010-03-01 Created: 2010-02-25 Last updated: 2013-01-08
In thesis
1. From Food Preference to Craving: Behavioural Traits and Molecular Mechanisms
Open this publication in new window or tab >>From Food Preference to Craving: Behavioural Traits and Molecular Mechanisms
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Preference for palatable and energy-dense foods may be a risk factor for body weight gain and has both genetic and environmental components. Once obesity develops in an individual, weight loss is difficult to achieve. Indeed, obesity is often characterized by repeated attempts to reduce the overconsumption of energy-dense foods, followed by food craving and relapse to overconsumption. Relapse and loss of control over intake are observed also in drug addicts, and it has been shown that obesity and drug addiction not only share behavioural features but also neural circuitry, e.g. the mesolimbic dopamine pathway. In this thesis, we sought to investigate the mechanisms related to food preferences and craving using animal models previously used in addiction research.

The risk of gaining weight may implicate behavioural traits and emotional states. We showed in rats that a risk-taking behavioural profile was associated both with increased preference for a high-fat (HF) diet and with increased motivational response to a palatable high-sucrose (HS) diet. Hypothalamic urocortin 2 expression was associated with the preference for the HF diet. We also tested the hypothesis that consumption of HS and HF diets separately or provided simultaneously (HFHS) affect anxiety-like behaviour and locomotion.

Furthermore, we showed that withdrawal from HFHS food affects diet-induced obesity-prone (OP) and obesity-resistant (OR) animals differently. OP animals had increased motivation (craving) for HS food pellets as measured by the operant self-administration technique during withdrawal. Dopamine receptor expression in the striatum differed between OP and OR animals both at access to HFHS and during withdrawal. This strongly implicates dopaminergic signaling in the OP phenotype.

In humans, food preferences may be monitored using questionnaires. We analyzed food preference data from parents of preschool children, and identified an inverse association of parental preference for high-fat high-protein food and overweight in children.

In conclusion, we have employed animal models previously used in the addiction field to identify molecular mechanisms related both to food preference and vulnerability to obesity, and to food craving associated with withdrawal from palatable food. These findings add to our current understanding of obesity.


Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2010. 93 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 526
Obesity, Reward, Food preferences, Dietary fats, Dietary carbohydrates, Anxiety, Dopamine, Craving, Operant self-administration
National Category
Pharmacology and Toxicology
Research subject
urn:nbn:se:uu:diva-119779 (URN)978-91-554-7734-9 (ISBN)
Public defence
2010-04-10, B42, BMC, Husargatan 3, Uppsala, 09:00 (English)
Available from: 2010-03-19 Created: 2010-03-01 Last updated: 2010-03-19Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Roman, Erika
By organisation
Functional PharmacologyDepartment of Pharmaceutical Biosciences
Medical and Health Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 229 hits
ReferencesLink to record
Permanent link

Direct link