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Dopamine and cyclic AMP-regulated phosphoprotein-32 phosphorylation pattern in cocaine and morphine-sensitized rats

Scheggi, Simona and Rauggi, Riccardo and Gambarana, Carla and Tagliamonte, Alessandro and De Montis, Maria Graziella (2004) Dopamine and cyclic AMP-regulated phosphoprotein-32 phosphorylation pattern in cocaine and morphine-sensitized rats. Journal of Neurochemistry, Vol. 90 (4), p. 792-799. eISSN 1471-4159. Article.

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DOI: 10.1111/j.1471-4159.2004.02510.x

Abstract

This study reports some of the modifications in dopaminergic signalling that accompany cocaine and morphine behavioural sensitization. Cocaine-sensitized rats showed increased phosphorylation of dopamine- and cyclic AMP-regulated phosphoprotein Mr 32 kDa (DARPP-32) at threonine-75 (Thr75) and decreased DARPP-32 phosphorylation at Thr34, in the caudate–putamen (CPu) and nucleus accumbens (NAc) 7 days after sensitization assessment. Conversely, in morphine-sensitized rats, no apparent modifications in DARPP-32 phosphorylation pattern were observed. Morphine-sensitized rats have increased binding and coupling of µ-opioid receptors and increased dopaminergic transmission in striatal areas and, upon morphine challenge, exhibit dopamine D1 receptor-dependent stereotypies. Thus, the DARPP-32 phosphorylation pattern was studied in morphine-sensitized rats at different times after morphine challenge. Morphine challenge increased levels of phospho-Thr75 DARPP-32 and decreased levels of phospho-Thr34 DARPP-32 in a time-dependent manner in the CPu and NAc. In order to assess whether these modifications were related to modified cyclic AMP-dependent protein kinase (PKA) activity, the phosphorylation levels of two other PKA substrates were examined, the GluR1 and NR1 subunits of α-amino-3-hydroxy-5-methylisoxazole-4-propionate and NMDA receptors respectively. The phosphorylation levels of GluR1 and NR1 subunits decreased in parallel with those of phospho-Thr-34 DARPP-32, supporting the hypothesis that morphine challenge elicited a decrease in PKA activity in morphine-sensitized rats.

Item Type:Article
ID Code:1339
Status:Published
Refereed:Yes
Uncontrolled Keywords:Caudate–putamen, dopaminergic D1 receptors, drugs of abuse, nucleus accumbens, protein kinase A activity
Subjects:Area 05 - Scienze biologiche > BIO/14 Farmacologia
Divisions:001 Università di Sassari > 01 Dipartimenti > Scienze del farmaco
Publisher:Blackwell / Wiley
eISSN:1471-4159
Copyright Holders:© 2004 International Society for Neurochemistry
Deposited On:18 Aug 2009 10:04

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