SENSITIZATION OF THE LOCOMOTOR RESPONSE TO PSYCHOSTIMULANTS AFTER REPEATED OPIATE EXPOSURE - ROLE OF THE NUCLEUS-ACCUMBENS

Citation
St. Cunningham et al., SENSITIZATION OF THE LOCOMOTOR RESPONSE TO PSYCHOSTIMULANTS AFTER REPEATED OPIATE EXPOSURE - ROLE OF THE NUCLEUS-ACCUMBENS, Neuropsychopharmacology, 16(2), 1997, pp. 147-155
Citations number
46
Categorie Soggetti
Neurosciences,Psychiatry,"Pharmacology & Pharmacy
Journal title
Neuropsychopharmacology
ISSN journal
0893133X → ACNP
Volume
16
Issue
2
Year of publication
1997
Pages
147 - 155
Database
ISI
SICI code
0893-133X(1997)16:2<147:SOTLRT>2.0.ZU;2-O
Abstract
The following experiments were performed to ascertain the role of the nucleus accumbens in opiate-dopamine interactions using measures of lo comotor activity. Three separate experiments were carried out. In Expe riment 1, rats received systemic morphine (10 mg/kg IP) or saline (1 m l/kg IP) every other day for 5 days, followed by systemic amphetamine (1.5 mg/kg) 48 hours following the fifth injection. Animals in the mor phine pretreatment group exhibited a sensitized locomotor response to amphetamine. In Experiment 2, animals received the same systemic pretr eatment and were subsequently given intraaccumbens saline, amphetamine (2.5 mu g/0.5 mu l) or cocaine (7 mu g/0.5 mu l), each separated by 4 8 hours. Morphine-pretreated animals showed enhanced motor activity in response to intraaccumbens microinfusion of the psychostimulant drugs . Finally, in Experiment 3, multiple microinjections of morphine (0.5 mu g/0.5 mu l) directly into the nucleus accumbens resulted in a poten tiated locomotor response to intraaccumbens amphetamine (2.5 mu g/0.5 mu l). These data indicate that the nucleus accumbens may contribute t o both the development and expression of opiate-stimulant cross-sensit ization. The neural basis of this sensitization is hypothesized to be a common intracellular pathway affected by both classes of drugs, such as the cyclic adenosine monophosphate (AMP) system. (C) 1997 American College of Neuropsychopharmacology [Neuropsychopharmacology 16:147-15 5, 1997]