Title
The neural consequences of repeated cocaine exposure revealed by functional MRI in awake rats
GSBS Program
Neuroscience
UMMS Affiliation
Department of Psychiatry, Center for Comparative NeuroImaging
Date
1-8-2005
Document Type
Article
Medical Subject Headings
Animals; Biogenic Monoamines; Brain; Brain Chemistry; Carbon Dioxide; Cocaine; Hemoglobins; Injections, Intraventricular; Magnetic Resonance Imaging; Male; Oxygen; Oxygen Consumption; Rats; Rats, Sprague-Dawley
Disciplines
Life Sciences | Medicine and Health Sciences | Neuroscience and Neurobiology
Abstract
The use of functional magnetic resonance imaging (fMRI) in animal models of cocaine addiction is an invaluable tool for investigating the neuroadaptations that lead to this psychiatric disorder. We used blood-oxygen-level-dependent (BOLD) MRI in awake rats to identify the neuronal circuits affected by repeated cocaine administration. Rats were given an injection of cocaine (15 mg/kg, i.p.) or its vehicle for 7 days, abstained from injections for 1 week, and challenged with an intracerebroventricular cocaine injection during functional imaging. Acute cocaine produced robust positive BOLD responses across well-known monoamine-enriched brain regions, such as the prefrontal cortex, nucleus accumbens, dorsal striatum, sensory cortex, hippocampus, thalamus, and midbrain areas. However, repeated cocaine administration resulted in lower BOLD responses in the prefrontal cortex, agranular insular cortex, nucleus accumbens, ventral pallidum, and dorsomedial thalamus, among other brain regions. Reductions in BOLD intensity were not associated with variations in cerebrovascular reactivity between drug naive rats and those repeatedly exposed to cocaine. Therefore, the lower metabolic activation in response to cocaine could reflect a reduced neuronal and/or synaptic activity upon repeated administration.
Rights and Permissions
Citation: Neuropsychopharmacology. 2005 May;30(5):936-43. Link to article on publisher's site