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A single exposure to morphine induces long-lasting hyporeactivity of rat caudate putamen dopaminergic nerve terminals
- Source :
- Annals of the New York Academy of Sciences. 1025
- Publication Year :
- 2004
-
Abstract
- The long-lasting effects of exposure to drugs of abuse on the brain is a central theme in drug addiction research. This study was designed to evaluate whether enduring neurochemical adaptations within caudate putamen can be evoked by a single injection of a high dose of morphine. Rats were pretreated once with 10 mg/kg morphine. Seven days later the effect of another injection of 10 mg/kg morphine on total levels of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanilic acid (HVA) in caudate putamen was assessed in half the pretreated animals. An irreversible mu-opioid receptor antagonist, cloccinamox (C-CAM; 0.1 mg/kg), significantly antagonized the elevation of the HVA/DA ratio, but not the elevation of the DOPAC/DA ratio induced by morphine in the caudate putamen from drug-naive animals. Pretreatment with morphine blunted changes in the HVA/DA ratio induced by another morphine challenge, but it had no effect on the DOPAC/DA ratio within the caudate putamen. Therefore, a single dose of 10 mg/kg morphine hampered nigrostriatal DA release and extraneuronal metabolism, mu-opioid receptor mediated, on another 10 mg/kg morphine challenge. This confirms that the first exposure to morphine does not go without long-lasting neurochemical adaptations.
- Subjects :
- Male
medicine.medical_specialty
Time Factors
medicine.drug_class
Dopamine
Presynaptic Terminals
Hyperkinesis
General Biochemistry, Genetics and Molecular Biology
Neurochemical
History and Philosophy of Science
Internal medicine
medicine
Animals
Rats, Wistar
Morphine
Chemistry
General Neuroscience
Dopaminergic
Putamen
Metabolism
Single injection
Receptor antagonist
Caudate putamen
Rats
Endocrinology
nervous system
Caudate Nucleus
medicine.drug
Subjects
Details
- ISSN :
- 00778923
- Volume :
- 1025
- Database :
- OpenAIRE
- Journal :
- Annals of the New York Academy of Sciences
- Accession number :
- edsair.doi.dedup.....9cb9556efd065a952a465ab043e50e5d