Volume 89, Issue 4 p. 853-860
Free Access

Cortical acetylcholine release is increased and γ-aminobutyric acid outflow is reduced during morphine withdrawal

T. Antonelli

T. Antonelli

Department of Pharmacology, University of Ferrara, Via Fossato di Mortara, 23, 44100 Ferrara, Italy

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L. Beani

Corresponding Author

L. Beani

Department of Pharmacology, University of Ferrara, Via Fossato di Mortara, 23, 44100 Ferrara, Italy

Department of Pharmacology, University of Ferrara, Via Fossato di Mortara, 23, 44100 Ferrara, ItalySearch for more papers by this author
C. Bianchi

C. Bianchi

Department of Pharmacology, University of Ferrara, Via Fossato di Mortara, 23, 44100 Ferrara, Italy

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S. Rando

S. Rando

Department of Pharmacology, University of Ferrara, Via Fossato di Mortara, 23, 44100 Ferrara, Italy

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M. Simonato

M. Simonato

Department of Pharmacology, University of Ferrara, Via Fossato di Mortara, 23, 44100 Ferrara, Italy

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S. Tanganelli

S. Tanganelli

Department of Pharmacology, University of Ferrara, Via Fossato di Mortara, 23, 44100 Ferrara, Italy

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First published: December 1986
Citations: 24

Abstract

  • 1

    The effects of naloxone on acetylcholine (ACh) and γ-aminobutyric acid (GABA) outflow from the cerebral cortex of freely moving, morphine-dependent guinea-pigs was studied.

  • 2

    The cortical efflux of ACh in chronically-treated guinea-pigs was about half of that of normal animals. GABA efflux was unaffected.

  • 3

    During opioid withdrawal precipitated by naloxone (0.1–10 mg kg−1, i.p.) the guinea-pigs showed jumping, hyperactivity and wet dog shakes, the intensity of which was directly related to the dose of naloxone. The withdrawal syndrome was accompanied by a dose-dependent increase in ACh release and reduction in GABA outflow; ACh release was increased by naloxone at doses lower (0.1–3 mg kg−1) than those acting on GABA efflux (1–10 mg kg−1). Atropine (10 mg kg−1) and diazepam (5 mg kg−1) did not prevent GABA and ACh changes.