Abstract
Drugs of abuse share the ability to enhance dopaminergic neurotransmission in the dorsal and ventral striatum. The action of dopamine is modulated by additional neurotransmitters, including glutamate, serotonin and adenosine. All these neurotransmitters regulate the phosphorylation state of Dopaminal serine/threonine protein phosphatase, PP-1. Phosphorylatine- and cAMP-regulated phosphoprotein, Mr 32 kDa (DARPP-32). Phosphorylation at Thr34 by protein kinase A converts DARPP-32 into a potent inhibitor of the multifunctioon at Thr75 by Cdk5 converts DARPP-32 into an inhibitor of protein kinase A. The state of phosphorylation of DARPP-32 at Thr34 also depends on the phosphorylation state of Ser97 and Ser130, which are phosphorylated by CK2 and CK1, respectively. By virtue of regulation of these 4 phosphorylation sites, and through its ability to modulate the activity of PP-1 and protein kinase A, DARPP-32 plays a key role in integrating a variety of biochemical, electrophysiological, and behavioral responses controlled by dopamine and other neurotransmitters. Importantly, there is now alarge body of evidence that supports a key role for DARPP-32-dependent signaling in mediating the actions of multiple drugs of abuse including cocaine, amphetamine, nicotine, caffeine, LSD, PCP, ethanol and morphine.
Keywords: protein phosphorylation, psychostimulants, dopamine, striatum
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References
- 1.Walaas SI, Aswad DW, Greengard P. A dopamine- and cyclic AMP-regulated phosphoprotein enriched in dopamine-innervated brain regions. Nature. 1983;301:69–71. doi: 10.1038/301069a0. [DOI] [PubMed] [Google Scholar]
- 2.Hemmings HC, Greengard P, Tung HY, Cohen P. DARPP-32, a dopamine-regulated neuronal phosphoprotein, is a potent inhibitor of protein phosphatase-1. Nature. 1984;310(5977):503–505. doi: 10.1038/310503a0. [DOI] [PubMed] [Google Scholar]
- 3.Ouimet CC, Langley-Gullion KC, Greengard P. Quantitative immunocytochemistry of DARPP-32-expressing neurons in the rat caudatoputamen. Brain Res. 1998;808:8–12. doi: 10.1016/S0006-8993(98)00724-0. [DOI] [PubMed] [Google Scholar]
- 4.Cruz e Silva EF, Fox CA, Ouimet CC, Gustafson E, Watson SJ, Greengard P. Differential expression of protein phosphatase 1 isoforms in mammalian brain. J Neurosci. 1995;15:3375–3389. doi: 10.1523/JNEUROSCI.15-05-03375.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Girault JA, Hemmings HC, Williams KR, Nairn AC, Greengard P. Phosphorylation of DARPP-32, a dopamine- and cAMP-regulated phosphoprotein, by casein kinase II. J Biol Chem. 1989;264:21748–21759. [PubMed] [Google Scholar]
- 6.Desouits F, Cohen D, Nairn AC, Greengard P, Girault JA. Phosphorylation of DARPP-32, a dopamine- and cAMP-regulated phosphoprotein, by casein kinase I in vitro and in vivo. J Biol Chem. 1995;270:8772–8778. doi: 10.1074/jbc.270.15.8772. [DOI] [PubMed] [Google Scholar]
- 7.Desdouits F, Siciliano JC, Greengard P, Girault JA. Dopamine- and cAMP-regulated phosphoprotein DARPP-32: phosphorylation of Ser-137 by casein kinase I inhibits dephosphorylation of Thr-34 by calcineurin. Proc Natl Acad Sci USA. 1995;92:2682–2685. doi: 10.1073/pnas.92.7.2682. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Bibb JA, Snyder GL, Nishi A, et al. Phosphorylation of DARPP-32 by Cdk5 modulates dopamine signalling in neurons. Nature. 1999;402:669–671. doi: 10.1038/45251. [DOI] [PubMed] [Google Scholar]
- 9.Ouimet CC, Miller PE, Hemmings HC, Walaas SI, Greengard P. DARPP-32, a dopamine- and adenosine 3′:5′-monophosphate-regulated phosphoprotein enriched in dopamine-innervated brain regions. III Immunocytochemical localization. J Neurosci. 1984;4:111–124. doi: 10.1523/JNEUROSCI.04-01-00111.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Yoshida M, Precht W. Monosynaptic inhibition of neurons of the substantia nigra by caudato-nigral fibers. Brain Res. 1971;32:225–228. doi: 10.1016/0006-8993(71)90170-3. [DOI] [PubMed] [Google Scholar]
- 11.Beckstead RM, Cruz CJ. Striatal axons to the globus pallidus, entopeduncular nucleus and substantia nigra come mainly from separate cell populations in cat. Neuroscience. 1986;19:147–158. doi: 10.1016/0306-4522(86)90012-6. [DOI] [PubMed] [Google Scholar]
- 12.Gerfen CR, Young WS. Distribution of striatonigral and striatopallidal peptidergic neurons in both patch and matrix compartments: an in situ hybridization histochemistry and fluorescent retrograde tracing study. Brain Res. 1988;460:161–167. doi: 10.1016/0006-8993(88)91217-6. [DOI] [PubMed] [Google Scholar]
- 13.Kawaguchi Y, Wilson CJ, Emson PC. Projection subtypes of rat neostriatal matrix cells revealed by intracellular injection of biocytin. J Neurosci. 1990;10:3421–3438. doi: 10.1523/JNEUROSCI.10-10-03421.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Anderson KD, Reiner A. Immunohistochemical localization of DARPP-32 in striatal projection neurons and striatal interneurons: implications for the localization of D1-like dopamine receptors on different types of striatal neurons. Brain Res. 1991;568:235–243. doi: 10.1016/0006-8993(91)91403-N. [DOI] [PubMed] [Google Scholar]
- 15.Ouimet CC, Greengard P. Distribution of DARPP-32 in the basal ganglia: an electron microscopic study. J Neurocytol. 1990;19:39–52. doi: 10.1007/BF01188438. [DOI] [PubMed] [Google Scholar]
- 16.Carboni E, Imperato A, Perezzani L, Chiara G. Amphetamine, cocaine, phencyclidine and nomifensive increase extracellular dopamine concentrations preferentially in the nucleus accumbens of freely moving rats. Neuroscience. 1989;28:653–661. doi: 10.1016/0306-4522(89)90012-2. [DOI] [PubMed] [Google Scholar]
- 17.Parsons LH, Koob GF, Weiss F. Serotonin dysfunction in the nucleus accumbens of rats during withdrawal after unlimited access to intravenous cocaine. J Pharmacol Exp Ther. 1995;274:1182–1191. [PubMed] [Google Scholar]
- 18.Svenningsson P, Nishi A, Fisone G, Girault JA, Nairn AC, Greengard P. DARPP-32: an integrator of neurotransmission. Annu Rev Pharmacol Toxicol. 2004;44:269–296. doi: 10.1146/annurev.pharmtox.44.101802.121415. [DOI] [PubMed] [Google Scholar]
- 19.Stoof JC, Kebabian JW. Opposing roles for D-1 and D-2 dopamine receptors in efflux of cyclic AMP from rat neostriatum. Nature. 1981;294:366–368. doi: 10.1038/294366a0. [DOI] [PubMed] [Google Scholar]
- 20.Bergson C, Levenson R, Goldman-Rakic PS, Lidow MS. Dopamine receptor-interacting proteins: the Ca(2+) connection in dopamine signaling. Trends Pharmacol Sci. 2003;24:486–492. doi: 10.1016/S0165-6147(03)00232-3. [DOI] [PubMed] [Google Scholar]
- 21.Nishi A, Snyder GL, Greengard P. Bidirectional regulation of DARPP-32 phosphorylation by dopamine. J Neurosci. 1997;17:8147–8155. doi: 10.1523/JNEUROSCI.17-21-08147.1997. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Gerfen CR, Engber TM, Mahan LC, et al. D1 and D2 dopamine receptor-regulated gene expression of striatonigral and striatopallidal neurons. Science. 1990;250:1429–1432. doi: 10.1126/science.2147780. [DOI] [PubMed] [Google Scholar]
- 23.Surmeier DJ, Song WJ, Yan Z. Coordinated expression of dopamine receptors in neostriatal medium spiny neurons. J Neurosci. 1996;16:6579–6591. doi: 10.1523/JNEUROSCI.16-20-06579.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Aizman O, Brismar H, Uhlen P, et al. Anatomical and physiological evidence for D1 and D2 dopamine receptor colocalization in neostriatal neurons. Nat Neurosci. 2000;3:226–230. doi: 10.1038/72929. [DOI] [PubMed] [Google Scholar]
- 25.Svenningsson P, Lindskog M, Ledent C, et al. Regulation of the phosphorylation of the dopamine- and cAMP-regulated phosphoprotein of 32 kDa in vivo by dopamine D1, dopamine D2, and adenosine A2A receptors. Proc Natl Acad Sci USA. 2000;97:1856–1860. doi: 10.1073/pnas.97.4.1856. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Lindskog M, Svenningsson P, Fredholm BB, Greengard P, Fisone G. Activation of dopamine D2 receptors decreases DARPP-32 phosphorylation in striatonigral and striatopallidal projection neurons via different mechanisms. Neuroscience. 1999;88:1005–1008. doi: 10.1016/S0306-4522(98)00411-4. [DOI] [PubMed] [Google Scholar]
- 27.Nishi A, Bibb JA, Snyder GL, Higashi H, Nairn AC, Greengard P. Amplification of dopaminergic signaling by a positive feedback loop. Proc Natl Acad Sci USA. 2000;97:12840–12845. doi: 10.1073/pnas.220410397. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Halpain S, Girault JA, Greengard P. Activation of NMDA receptors induces dephosphorylation of DARPP-32 in rat striatal slices. Nature. 1990;343:369–372. doi: 10.1038/343369a0. [DOI] [PubMed] [Google Scholar]
- 29.Nishi A, Bibb JA, Matsuyama S, et al. Regulation of DARPP-32 dephosphorylation at PKA- and Cdk5-sites by NMDA and AMPA receptors: distinct roles of calcineurin and protein phosphatase-2A. J Neurochem. 2002;81:832–841. doi: 10.1046/j.1471-4159.2002.00876.x. [DOI] [PubMed] [Google Scholar]
- 30.Schoepp DD, Jane DE, Monn JA. Pharmacological agents acting at subtypes of metabotropic glutamate receptors. Neuropharmacology. 1999;38:1431–1476. doi: 10.1016/S0028-3908(99)00092-1. [DOI] [PubMed] [Google Scholar]
- 31.Tallaksen-Greene SJ, Kaatz KW, Romano C, Albin RL. Localization of mGluR1a-like immunoreactivity and mGluR5-like immunoreactivity in identified populations of striatal neurons. Brain Res. 1998;780:210–217. doi: 10.1016/S0006-8993(97)01141-4. [DOI] [PubMed] [Google Scholar]
- 32.Testa CM, Friberg IK, Weiss SW, Standaert DG. Immunohistochemical localization of metabotropic glutamate receptors mGluR1a and mGluR2/3 in the rat basal ganglia. J Comp Neurol. 1998;390:5–19. doi: 10.1002/(SICI)1096-9861(19980105)390:1<5::AID-CNE2>3.0.CO;2-6. [DOI] [PubMed] [Google Scholar]
- 33.Nishi A, Liu F, Matsuyama S, et al. Metabotropic mGlu5 receptors regulate adenosine A2A receptor signaling. Proc Natl Acad Sci USA. 2003;100:1322–1327. doi: 10.1073/pnas.0237126100. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 34.Liu F, Ma XH, Ule J, et al. Regulation of cyclin-dependent kinase 5 and casein kinase 1 by metabotropic glutamate receptors. Proc Natl Acad Sci USA. 2001;98:11062–11068. doi: 10.1073/pnas.191353898. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 35.Liu F, Virshup DM, Nairn AC, Greengard P. Mechanism of regulation of casein kinase I activity by group I metabotropic glutamate receptors. J Biol Chem. 2002;277:45393–45399. doi: 10.1074/jbc.M204499200. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 36.Nishi A, Watanabe Y, Higashi H, Tanaka M, Nairn AC, Greengard P. Glutamate regulation of DARPP-32 phosphorylation in neostriatal neurons involves activation of multiple signaling cascades. Proc Natl Acad Sci USA. 2005;102:1199–1204. doi: 10.1073/pnas.0409138102. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 37.Barnes NM, Sharp T. A review of central 5-HT receptors and their function. Neuropharmacology. 1999;38:1083–1152. doi: 10.1016/S0028-3908(99)00010-6. [DOI] [PubMed] [Google Scholar]
- 38.Svenningsson P, Tzavara ET, Liu F, Fienberg AA, Nomikos GG, Greengard P. DARPP-32 mediates serotonergic neurotransmission in the forebrain. Proc Natl Acad Sci USA. 2002;99:3188–3193. doi: 10.1073/pnas.052712699. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 39.Schiffmann SN, Jacobs O, Vanderhaeghen JJ. Striatal restricted adenosine A2 receptor (RDC8) is expressed by enkephalin but not by substance P neurons: an in situ hybridization histochemistry study. J Neurochem. 1991;57:1062–1067. doi: 10.1111/j.1471-4159.1991.tb08257.x. [DOI] [PubMed] [Google Scholar]
- 40.Svenningsson P, Lindskog M, Rognoni F, Fredholm BB, Greengard P, Fisone G. Activation of adenosine A2A and dopamine D1 receptors stimulates cyclic AMP-dependent phosphorylation of DARPP-32 in distinct populations of striatal projection neurons. Neuroscience. 1998;84:223–228. doi: 10.1016/S0306-4522(97)00510-1. [DOI] [PubMed] [Google Scholar]
- 41.Lindskog M, Svenningsson P, Pozzi L, et al. Involvement of DARPP-32 phosphorylation in the stimulant action of caffeine. Nature. 2002;418:774–778. doi: 10.1038/nature00817. [DOI] [PubMed] [Google Scholar]
- 42.Hyman SE, Malenka RC. Addiction and the brain: the neurobiology of compulsion and its persistence. Nat Rev Neurosci. 2001;2:695–703. doi: 10.1038/35094560. [DOI] [PubMed] [Google Scholar]
- 43.Nestler EJ. Molecular basis of long-term plasticity underlying addiction. Nat Rev Neurosci. 2001;2:119–128. doi: 10.1038/35053570. [DOI] [PubMed] [Google Scholar]
- 44.Fienberg AA, Hiroi N, Mermelstein PG, et al. DARPP-32: regulator of the efficacy of dopaminergic neurotransmission. Science. 1998;281:838–842. doi: 10.1126/science.281.5378.838. [DOI] [PubMed] [Google Scholar]
- 45.Svenningsson P, Tzavara ET, Carruthers R, et al. Diverse psychotomimetics act through a common on signaling pathway. Science. 2003;302:1412–1415. doi: 10.1126/science.1089681. [DOI] [PubMed] [Google Scholar]
- 46.Fienberg AA, Greengard P. The DARPP-32 knockout mouse. Brain Res Brain Res Rev. 2000;31:313–319. doi: 10.1016/S0165-0173(99)00047-8. [DOI] [PubMed] [Google Scholar]
- 47.Nairn AC, Svenningsson P, Nishi A, Fisone G, Girault JA, Greengard P. The role of DARPP-32 in the actions of drugs of abuse. Neuropharmacology. 2004;47:14–23. doi: 10.1016/j.neuropharm.2004.05.010. [DOI] [PubMed] [Google Scholar]
- 48.Valjent E, Pascoli V, Svenningsson P, et al. Regulation of a protein phosphatase cascade allows convergent dopamine and glutamate signals to activate ERK in the striatum. Proc Natl Acad Sci USA. 2005;102:491–496. doi: 10.1073/pnas.0408305102. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 49.Bibb JA, Chen J, Taylor JR, et al. Effects of chronic exposure to cocaine are regulated by the neuronal protein Cdk5. Nature. 2001;410:376–380. doi: 10.1038/35066591. [DOI] [PubMed] [Google Scholar]
- 50.Liu FC, Graybiel AM. Spatiotemporal dynamics of CREB phosphorylation: transient versus sustained phosphorylation in the developing striatum. Neuron. 1996;17:1133–1144. doi: 10.1016/S0896-6273(00)80245-7. [DOI] [PubMed] [Google Scholar]
- 51.Hagiwara M, Alberts A, Brindle P, et al. Transcriptional attenuation following cAMP induction requires PP-1-mediated dephosphorylation of CREB. Cell. 1992;70:105–113. doi: 10.1016/0092-8674(92)90537-M. [DOI] [PubMed] [Google Scholar]
- 52.Yan Z, Feng J, Fienberg AA, Greengard P. D(2) dopamine receptors induce mitogen-activated protein kinase and cAMP response element-binding protein phosphorylation in neurons. Proc Natl Acad Sci USA. 1999;96:11607–11612. doi: 10.1073/pnas.96.20.11607. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 53.Svenningsson P, Fienberg AA, Allen PB, et al. Dopamine D(1) receptor-induced gene transcription is modulated by DARPP-32. J Neurochem. 2000;75:248–257. doi: 10.1046/j.1471-4159.2000.0750248.x. [DOI] [PubMed] [Google Scholar]
- 54.Hiroi N, Fienberg AA, Haile CN, et al. Neuronal and behavioral abnormalities in striatal function in DARPP-32-mutant mice. Eur J Neurosci. 1999;11:1114–1118. doi: 10.1046/j.1460-9568.1999.00570.x. [DOI] [PubMed] [Google Scholar]
- 55.Zachariou V, Benoit-Marand M, Allen PB, et al. Reduction of cocaine place preference in mice lacking the protein phosphatase 1 inhibitors DARPP32 or Inhibitor 1. Biol Psychiatry. 2002;51:612–620. doi: 10.1016/S0006-3223(01)01318-X. [DOI] [PubMed] [Google Scholar]
- 56.Heyser CJ, Fienberg AA, Greengard P, Gold LH. DARPP-32 knockout mice exhibit impaired reversal learning in a discriminated operant task. Brain Res. 2000;867:122–130. doi: 10.1016/S0006-8993(00)02272-1. [DOI] [PubMed] [Google Scholar]
- 57.Schoffelmeer AN, Hansen HA, Stoof JC, Mulder AH. Blockade of D-2 dopamine receptors trongly enhances the potency of enkephalins to inhibit dopamine-sensitive adenylate cyclase in rat neostriatum: involvement of delta- and mu-opioid receptors. J Neurosci. 1986;6:2235–2239. doi: 10.1523/JNEUROSCI.06-08-02235.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 58.Georges F, Stinus L, Bloch B, Moine C. Chronic morphine exposure and spontaneous withdrawal are associated with modifications of dopamine receptor and neuropeptide gene expression in the rat striatum. Eur J Neurosci. 1999;11:481–490. doi: 10.1046/j.1460-9568.1999.00462.x. [DOI] [PubMed] [Google Scholar]
- 59.Lindskog M, Svenningsson P, Fredholm B, Greengard P, Fisone G. Mu- and delta-opioid receptor agonists inhibit DARPP-32 phosphorylation in distinct populations of striatal projection neurons. Eur J Neurosci. 1999;11:2182–2186. doi: 10.1046/j.1460-9568.1999.00597.x. [DOI] [PubMed] [Google Scholar]
- 60.Role LW, Berg DK. Nicotinic receptors in the development and modulation of CNS synapses. Neuron. 1996;16:1077–1085. doi: 10.1016/S0896-6273(00)80134-8. [DOI] [PubMed] [Google Scholar]
- 61.Wonnacott S. Presynaptic nicotinic ACh receptors. Trends Neurosci. 1997;20:92–98. doi: 10.1016/S0166-2236(96)10073-4. [DOI] [PubMed] [Google Scholar]
- 62.Ramirez-Latorre J, Crabtree G, Turner J, Role L. Molecular composition and biophysical characteristics of nicotinic receptors. In: Arneric SP, Brioni JD, editors. Neuronal nicotinic receptors: pharmacology and therapeutic opportunities. New York: Wiley-Liss, Inc; 1999. pp. 43–64. [Google Scholar]
- 63.Zoli M, Moretti M, Zanardi A, McIntosh JM, Clementi F, Gotti C. Identification of the nicotinic receptor subtypes expressed on dopaminergic terminals in the rat striatum. J Neurosci. 2002;22:8785–8789. doi: 10.1523/JNEUROSCI.22-20-08785.2002. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 64.Nomikos GG, Schilstrom B, Hildebrand BE, Panagis G, Grenhoff J, Svensson TH. Role of alpha7 nicotinic receptors in nicotine dependence and implications for psychiatric illness. Behav Brain Res. 2000;113:97–103. doi: 10.1016/S0166-4328(00)00204-7. [DOI] [PubMed] [Google Scholar]
- 65.Hamada M, Higashi H, Nairn AC, Greengard P, Nishi A. Differential regulation of dopamine D1 and D2 signaling by nicotine in neostriatal neurons. J Neurochem. 2004;90:1094–1103. doi: 10.1111/j.1471-4159.2004.02574.x. [DOI] [PubMed] [Google Scholar]
- 66.Aghajanian GK, Marek GJ. Serotonin and hallucinogens. Neuropsychopharmacology. 1999;21:16S–23S. doi: 10.1016/S0893-133X(98)00135-3. [DOI] [PubMed] [Google Scholar]
- 67.Grailhe R, Waeber C, Dulawa SC, et al. Increased exploratory activity and altered response to LSD in mice lacking the 5-HT(5A) receptor. Neuron. 1999;22:581–591. doi: 10.1016/S0896-6273(00)80712-6. [DOI] [PubMed] [Google Scholar]
- 68.Glennon RA, Titeler M, McKenney JD. Evidence for 5-HT2 involvement in the mechanism of action of hallucinogenic agents. Life Sci. 1984;35:2505–2511. doi: 10.1016/0024-3205(84)90436-3. [DOI] [PubMed] [Google Scholar]
- 69.Sawa A, Snyder SH. Schizophrenia: diverse approaches to a complex disease. Science. 2002;296:692–695. doi: 10.1126/science.1070532. [DOI] [PubMed] [Google Scholar]
- 70.Carlezon WA, Wise RA. Rewarding actions of phencyclidine and related drugs in nucleus accumbens shell and frontal cortex. J Neurosci. 1996;16:3112–3122. doi: 10.1523/JNEUROSCI.16-09-03112.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 71.Druhan JP, Rajabi H, Stewart J. MK-801 increases locomotor activity without elevating extracellular dopamine levels in the nucleus accumbens. Synapse. 1996;24:135–146. doi: 10.1002/(SICI)1098-2396(199610)24:2<135::AID-SYN5>3.0.CO;2-G. [DOI] [PubMed] [Google Scholar]
- 72.Pierce RC, Meil WM, Kalivas PW. The NMDA antagonist, dizocilpine, enhances cocaine reinforcement without influencing mesoaccumbens dopamine transmission. Psychopharmacology (Berl). 1997;133:188–195. doi: 10.1007/s002130050390. [DOI] [PubMed] [Google Scholar]
- 73.Svenningsson P, Moine C, Fisone G, Fredholm BB. Distribution, biochemistry and function of striatal adenosine A2A receptors. Prog Neurobiol. 1999;59:355–396. doi: 10.1016/S0301-0082(99)00011-8. [DOI] [PubMed] [Google Scholar]
- 74.Ledent C, Vaugeois JM, Schiffmann SN, et al. Aggressiveness, hypoalgesia and high blood pressure in mice lacking the adenosine A2a receptor. Nature. 1997;388:674–678. doi: 10.1038/41771. [DOI] [PubMed] [Google Scholar]
- 75.Risinger FO, Freeman PA, Greengard P, Fienberg AA. Motivational effects of ethanol in DARPP-32 knock-out mice. J Neurosci. 2001;21:340–348. doi: 10.1523/JNEUROSCI.21-01-00340.2001. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 76.Maldve RE, Zhang TA, Ferrani-Kile K, et al. DARPP-32 and regulation of the ethanol sensitivity of NMDA receptors in the nucleus accumbens. Nat Neurosci. 2002;5:641–648. doi: 10.1038/nn877. [DOI] [PubMed] [Google Scholar]