The behavioural and neurological effects of excessive sucrose intake overlap with those of abused drugs, suggesting that sucrose bingeing should be categorized with addictive disorders. Behaviorally, a primary characteristic of drug addiction is compulsive responding, manifested as an inability to inhibit drug intake despite negative consequences. We examined whether excessive sucrose self-administration produces these behavioural patterns using a validated rat model of sucrose bingeing (Avena et al., 2008) and investigated potential neurophysiological correlates with brain slice electrophysiology. Rats (n = 8-16 per group) received 12 or 24 hour access to a 10% sucrose solution and food, while control groups received food only or a 0.1% saccharin solution with food, each day for 28 days. Sucrose/saccharin/food consumption and weight were recorded daily. Compulsive responding for sucrose was assessed one or 28 days after the final self-administration session using a conditioned suppression paradigm. Persistent responding in the presence of a cue (tone) predicting a negative outcome (0.5 mA footshock) was used as a measure of compulsive responding. Only rats given 12-hour access to sucrose developed a binge pattern of intake, in which solution consumption increased dramatically during the first hour of each session. This group also developed compulsive responding for sucrose, exhibiting a reduced conditioned suppression effect following both one day and 28 days of abstinence. At a neural level, there was a switch in direction (from reduction to enhancement) in dopaminergic (DA) modulation of GABA synaptic transmission in the oval bed nucleus of the stria terminalis (ovBNST) of rats that developed a binge pattern of sucrose intake. This switch was similar to that recently observed in rats displaying enhanced motivation to self-administer cocaine. Therefore, excessive intermittent sucrose consumption produces compulsive responding and this shift from controlled to compulsive intake may involve the same neural mechanisms that underlie excessive cocaine self-administration. / Thesis (Master, Psychology) -- Queen's University, 2012-09-28 09:28:10.705
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OKQ.1974/7537 |
| Date | 28 September 2012 |
| Creators | Maracle, AMANDA |
| Contributors | Queen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.)) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. |
| Relation | Canadian theses |
Page generated in 0.002 seconds