Increase of extracellular dopamine in the medial prefrontal cortex during spontaneous and naloxone-precipitated opiate abstinence

Abstinence from chronic morphine has been shown to reduce extracellular dopamine in the nucleus accumbens as measured by brain microdialysis (Acquas et al. 1991). In the present study, we investigated if similar changes take place in the prefrontal cortex. Withdrawal from a schedule of increasing do...

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Bibliographic Details
Published in:Psychopharmacologia 1995-11, Vol.122 (2), p.202-205
Main Authors: BASSAREO, V, TANDA, G, DI CHIARA, G
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Dopamine - metabolism
Drug toxicity and drugs side effects treatment
Extracellular Space - drug effects
Extracellular Space - metabolism
Male
Medical sciences
Microdialysis
Miscellaneous (drug allergy, mutagens, teratogens...)
Morphine Dependence - metabolism
Naloxone - pharmacology
Narcotic Antagonists - pharmacology
Pharmacology. Drug treatments
Prefrontal Cortex - metabolism
Rats
Rats, Sprague-Dawley
Substance Withdrawal Syndrome - metabolism
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Summary:Abstinence from chronic morphine has been shown to reduce extracellular dopamine in the nucleus accumbens as measured by brain microdialysis (Acquas et al. 1991). In the present study, we investigated if similar changes take place in the prefrontal cortex. Withdrawal from a schedule of increasing doses of morphine administered intraperitoneally twice a day for 9 days up to a daily dose of 60 mg/kg resulted in doubling of basal extracellular concentrations of dopamine in the prefrontal cortex and in a mild withdrawal syndrome (ptosis, piloerection, hunched-back posture). Administration of a low dose of naloxone (0.5 mg/kg SC) to rats withdrawn from chronic morphine resulted in a full withdrawal syndrome with wet dog shakes and diarrhoea and an increase of extracellular dopamine that peaked at 40 min and returned to the pre-naloxone values by 80 min. The results show that dopamine neurotransmission in the medial prefrontal cortex responds to opiate withdrawal in a manner opposite to dopamine transmission in the nucleus accumbens and indicate that the dopamine system is affected by abstinence in a topographically specific manner, consistent with a different functional role of mesocortical as compared to mesolimbic dopamine systems.
ISSN:0033-3158
1432-2072
DOI:10.1007/BF02246097