1. ¹Department of Psychiatry and Center for Basic Neuroscience, The University of Texas Southwestern Medical Center, Dallas, TX, USA
2. ²Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, NY, USA
3. ³Department of Basic Sciences, University of Crete, Heraklion, Crete, Greece
4. ⁴Intra-Cellular Therapies, Inc., New York, NY, USA
5. ⁵Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA

Correspondence: Professor EJ Nestler, Department of Psychiatry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9070, USA. Tel: +1 214 648 1111; Fax: +1 214 648 4947; E-mail: eric.nestler@utsouthwestern.edu

⁶These authors contributed equally to this study.

⁷Current address: INSERM U704, Dynamique des réseaux neuronaux, Joseph Fourier University of Grenoble, 2280 rue de la Piscine, BP53, Grenoble, 38041, France.

Received 10 February 2005; Revised 1 June 2005; Accepted 3 June 2005; Published online 3 August 2005.

Abstract

Mice lacking DARPP-32, a striatal-enriched phosphoprotein, show abnormal behavioral and biochemical responses to cocaine, but the role of individual phosphorylation sites in DARPP-32 in these responses is unknown. We show here that mutation of Thr-34 in DARPP-32 mimicked the behavioral phenotype of the constitutive DARPP-32 knockout in cocaine-induced place conditioning, locomotor activity, and sensitization paradigms. In contrast, mutations of Thr75 did not affect conditioned place preference or the acute locomotor response to cocaine, but DARPP-32 Thr-75 mutants showed no locomotor sensitization in response to repeated cocaine administration. Consistent with these behavioral findings, we found that cocaine regulation of gene expression in striatum, including the acute induction of the immediate early genes c-fos and arc (activity-regulated cytoskeletal-associated gene), was abolished in DARPP-32 Thr-34 mutants, but not in Thr-75 mutants. Similarly, induction of the transcription factor FosB in the ventral striatum (nucleus accumbens) by chronic cocaine was diminished by the Thr-34, but not the Thr-75, mutation. These findings highlight distinct roles of the Thr-34 and Thr-75 phosphorylation sites of DARPP-32 in mediating short- and long-term behavioral and biochemical actions of cocaine.