title: Cocaine self-administration leads to alterations in temporal responses to cocaine challenge in limbic and motor circuitry.
abstract: Chronic use of cocaine is associated with lasting alterations in brain metabolism, circuitry, and receptor properties. We used neuroimaging with pharmacological magnetic resonance imaging to assess alterations in response to cocaine (0.5 mg/kg) in animals trained to self-administer cocaine on a fixed-ratio 5 schedule of reinforcement, as well as saline-yoked controls, after 28 days of cocaine abstinence. We fitted the cerebral blood volume (CBV) curves for full-width half-maximum (FWHM) as well as peak CBV response. There were significant increases in the FWHM of the response curves in the cocaine self-administering (SA) animals as compared with saline-yoked controls in the medial prefrontal cortex (mPFC) and the caudate/putamen (CPu), and increases in peak CBV in the M1 motor cortex, CPu, and pedunculopontine tegmental nucleus. Functional connectivity analysis showed increased correlations in the cocaine SA rats upon acute cocaine challenge, especially in the S1, mPFC, and thalamus. As D3 receptor expression is postulated to increase following chronic cocaine administration, we also examined the response to 0.2 mg/kg of the D3-preferring agonist 7-hydroxy-N,N-di-n-propyl-2-aminotetralin (7-OHDPAT). Cocaine SA animals showed a decreased overall CBV response to this drug, except in the globus pallidus. The hypothalamus showed a negative CBV change in response to cocaine challenge, similar to that noted with the D3 agonist, and showed a smaller response in the cocaine SA animals than in the controls. Given the good coupling of cerebral hemodynamics with dopamine dynamics previously observed with pharmacological magnetic resonance imaging, these data suggest that increased persistence of dopamine in the prefrontal cortex may be responsible for some of the behavioral alterations observed subsequent to chronic cocaine use.
authors: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA. iris@nmr.mgh.harvard.edu
authors: Y Iris
authors: YI
authors: Chen
authors: K
authors: K
authors: Famous
authors: H
authors: H
authors: Xu
authors: J-K
authors: JK
authors: Choi
authors: Joseph B
authors: JB
authors: Mandeville
authors: H D
authors: HD
authors: Schmidt
authors: R Christopher
authors: RC
authors: Pierce
authors: Bruce G
authors: BG
authors: Jenkins
mesh_terms: D000818:Animals; D001921:Brain / Q000033:anatomy & histology* / Q000187:drug effects* / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000187:drug effects; D003042:Cocaine / Q000008:administration & dosage* / Q000494:pharmacology*; D018491:Dopamine Agonists / Q000494:pharmacology; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D006801:Humans; D008032:Limbic System / Q000033:anatomy & histology* / Q000187:drug effects* / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000187:drug effects; D012054:Reinforcement, Psychology; D012646:Self Administration; D013764:Tetrahydronaphthalenes / Q000494:pharmacology
chemical_list: D018491:Dopamine Agonists; D018765:Dopamine Uptake Inhibitors; D013764:Tetrahydronaphthalenes; D003042:Cocaine; C031349:7-hydroxy-2-N,N-dipropylaminotetralin