Steketee JD, Beyer CE. Injections of baclofen into the ventral medial prefrontal cortex block the initiation, but not the expression, of cocaine sensitization in rats.
Psychopharmacology (Berl) 2005;
180:352-8. [PMID:
15696327 DOI:
10.1007/s00213-005-2149-y]
[Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2004] [Accepted: 12/06/2004] [Indexed: 11/27/2022]
Abstract
RATIONALE
Increased excitatory output from the medial prefrontal cortex (mPFC) is thought to play a key role in the development of sensitization to cocaine. Gamma-aminobutyric acid (GABA) inhibits this excitatory output.
OBJECTIVES
The present studies were designed to determine the effects of intra-mPFC injections of the GABA(B) agonist baclofen on cocaine-induced motor activity and on the development of sensitization to cocaine.
METHODS
Rats received bilateral cannula implants above the ventral mPFC. Initial studies examined the dose-response effects of injection of baclofen (0.05-0.5 nmol/side) into the mPFC on the acute motor-stimulant response to cocaine (15 mg/kg, i.p.). Additional studies determined whether coadministration of intra-mPFC baclofen (0.5 nmol/side) and systemic cocaine (15 mg/kg, i.p.) could alter the initiation and/or expression of cocaine-induced behavioral sensitization.
RESULTS
Intra-mPFC baclofen dose-dependently blocked cocaine-induced motor activity. In sensitization studies, intra-mPFC baclofen was able to prevent the initiation, but not the expression of cocaine-induced sensitization.
CONCLUSIONS
The data suggest that the ability of GABA to modulate excitatory output from the mPFC may be attenuated in animals sensitized to cocaine.
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