RESUMO
The striatum plays a fundamental role in motor learning and reward-related behaviors that are synergistically shaped by populations of D1 dopamine receptor (D1R)- and D2 dopamine receptor (D2R)-expressing medium spiny neurons (MSNs). How various neurotransmitter inputs converging on common intracellular pathways are parsed out to regulate distinct behavioral outcomes in a neuron-specific manner is poorly understood. Here, we reveal that distinct contributions of D1R-MSNs and D2R-MSNs towards reward and motor behaviors are delineated by the multifaceted signaling protein neurofibromin 1 (NF1). Using genetic mouse models, we show that NF1 in D1R-MSN modulates opioid reward, whereas loss of NF1 in D2R-MSNs delays motor learning by impeding the formation and consolidation of repetitive motor sequences. We found that motor learning deficits upon NF1 loss were associated with the disruption in dopamine signaling to cAMP in D2R-MSN. Restoration of cAMP levels pharmacologically or chemogenetically rescued the motor learning deficits seen upon NF1 loss in D2R-MSN. Our findings illustrate that multiplex signaling capabilities of MSNs are deployed at the level of intracellular pathways to achieve cell-specific control over behavioral outcomes.
Assuntos
Corpo Estriado/fisiologia , Neurofibromina 1/metabolismo , Neurônios/fisiologia , Animais , AMP Cíclico/metabolismo , Dopamina/metabolismo , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Modelos Animais , Atividade Motora/fisiologia , Neurônios/metabolismo , Receptores de Dopamina D1/metabolismo , Receptores de Dopamina D2/metabolismo , Recompensa , Transdução de SinaisRESUMO
Stress profoundly affects physiological properties of neurons across brain circuits and thereby increases the risk for depression. However, the molecular and cellular mechanisms mediating these effects are poorly understood. In this study, we report that chronic physical restraint stress in mice decreases excitability specifically in layer 2/3 of pyramidal neurons within the prelimbic subarea of the prefrontal cortex (PFC) accompanied by the induction of depressive-like behavioral states. We found that a complex between G protein-coupled receptor (GPCR) 158 (GPR158) and regulator of G protein signaling 7 (RGS7), a regulatory GPCR signaling node recently discovered to be a key modulator of affective behaviors, plays a key role in controlling stress-induced changes in excitability in this neuronal population. Deletion of GPR158 or RGS7 enhanced excitability of layer 2/3 PFC neurons and prevented the impact of stress. Investigation of the underlying molecular mechanisms revealed that the A-type potassium channel Kv4.2 subunit is a molecular target of the GPR158-RGS7 complex. We further report that GPR158 physically associates with Kv4.2 channel and promotes its function by suppressing inhibitory modulation by cAMP-protein kinase A (PKA)-mediated phosphorylation. Taken together, our observations reveal a critical mechanism that adjusts neuronal excitability in L2/3 pyramidal neurons of the PFC and may thereby modulate the effects of stress on depression.
Assuntos
Canais de Potássio de Abertura Dependente da Tensão da Membrana/metabolismo , Córtex Pré-Frontal/metabolismo , Células Piramidais/metabolismo , Proteínas RGS/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais , Animais , Células Cultivadas , Feminino , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas RGS/deficiência , Receptores Acoplados a Proteínas G/deficiênciaRESUMO
In the striatum, medium spiny neurons (MSNs) are heavily involved in controlling movement and reward. MSNs form two distinct populations expressing either dopamine receptor 1 (D1-MSN) or dopamine receptor 2 (D2-MSN), which differ in their projection targets and neurochemical composition. The activity of both types of MSNs is shaped by multiple neuromodulatory inputs processed by GPCRs that fundamentally impact their synaptic properties biasing behavioral outcomes. How these GPCR signaling cascades are regulated and what downstream targets they recruit in D1-MSN and D2-MSN populations are incompletely understood. In this study, we examined the cellular and molecular mechanisms underlying the action of RGS9-2, a key GPCR regulator in MSNs implicated in both movement control and actions of addictive drugs. Imaging cultured striatal neurons, we found that ablation of RGS9-2 significantly reduced calcium influx through NMDARs. Electrophysiological recordings in slices confirmed inhibition of NMDAR function in MSNs, resulting in enhanced AMPAR/NMDAR ratio. Accordingly, male mice lacking RGS9-2 displayed behavioral hypersensitivity to NMDAR blockade by MK-801 or ketamine. Recordings from genetically identified populations of striatal neurons revealed that these changes were selective to D2-MSNs. Surprisingly, we found that these postsynaptic effects resulted in remodeling of presynaptic inputs to D2-MSNs increasing the frequency of mEPSC and inhibiting paired-pulse ratio. Pharmacological dissection revealed that these adaptations were mediated by the NMDAR-dependent inhibition of retrograde endocannabinoid signaling from D2-MSNs to CB1 receptor on presynaptic terminals. Together, these data demonstrate a novel mechanism for pathway selective regulation of synaptic plasticity in MSNs controlled by GPCR signaling.SIGNIFICANCE STATEMENT This study identifies a role for a major G-protein regulator in controlling synaptic properties of striatal neurons in a pathway selective fashion.
Assuntos
Corpo Estriado/fisiologia , Neurônios Dopaminérgicos/fisiologia , Proteínas RGS/fisiologia , Transmissão Sináptica/fisiologia , Animais , Sinalização do Cálcio , Células Cultivadas , Corpo Estriado/citologia , Neurônios Dopaminérgicos/química , Neurônios Dopaminérgicos/classificação , Neurônios Dopaminérgicos/efeitos dos fármacos , Endocanabinoides/fisiologia , Comportamento Exploratório , Feminino , Genes Reporter , Ácido Glutâmico/metabolismo , Masculino , Camundongos , Camundongos Knockout , Técnicas de Patch-Clamp , Terminações Pré-Sinápticas/metabolismo , Proteínas RGS/deficiência , Proteínas RGS/genética , Receptor CB1 de Canabinoide/antagonistas & inibidores , Receptor CB1 de Canabinoide/fisiologia , Receptores de Dopamina D2/análise , Receptores de Dopamina D2/genética , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Receptores de N-Metil-D-Aspartato/fisiologia , Teste de Desempenho do Rota-Rod , Sinapses/fisiologiaRESUMO
The dopamine D2 receptor (D2DR) regulates Akt and may also target the Wnt pathway, two signalling cascades that inhibit glycogen synthase kinase-3 (GSK-3). This study examined whether the Wnt pathway is regulated by D2DR and the role of Akt and dishevelled-3 (Dvl-3) in regulating GSK-3 and the transcription factor ß-catenin in the rat brain. Western blotting showed that subchronic treatment of raclopride (D2DR antagonist) increase phosphorylated Akt, Dvl-3, GSK-3, phosphorylated GSK-3 and ß-catenin, whereas subchronic treatment of quinpirole (D2DR agonist) induced the opposite response. Co-immunopreciptations revealed an association between GSK-3 and the D2DR complex that was altered following raclopride and quinpirole, albeit in opposite directions. SCH23390 (D1DR antagonist) and nafadotride (D3DR antagonist) were also used to determine if the response was specific to the D2DR. Neither subchronic treatment affected Dvl-3, GSK-3, Akt nor ß-catenin protein levels, although nafadotride altered the phosphorylation state of Akt and GSK-3. In addition, in-vitro experiments were conducted to manipulate Akt and Dvl-3 activity in SH-SY5Y cells to elucidate how the pattern of change observed following manipulation of D2DR developed. Results indicate that Akt affects the phosphorylation state of GSK-3 but has no effect on ß-catenin levels. However, altering Dvl-3 levels resulted in changes in Akt and the Wnt pathway similar to what was observed following raclopride or quinpirole treatment. Collectively, the data suggests that the D2DR very specifically regulates Wnt and Akt signalling via Dvl-3.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Quinase 3 da Glicogênio Sintase/metabolismo , Proteína Oncogênica v-akt/metabolismo , Fosfoproteínas/metabolismo , Córtex Pré-Frontal/metabolismo , Receptores de Dopamina D2/metabolismo , Androstadienos/farmacologia , Animais , Linhagem Celular Tumoral , Proteínas Desgrenhadas , Dopaminérgicos/farmacologia , Inibidores Enzimáticos/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Imunoprecipitação , Masculino , Neuroblastoma/patologia , Fosforilação/efeitos dos fármacos , Fosforilação/genética , Córtex Pré-Frontal/efeitos dos fármacos , RNA Interferente Pequeno/metabolismo , RNA Interferente Pequeno/farmacologia , Ratos , Ratos Sprague-Dawley , Receptores de Dopamina D2/genética , Transdução de Sinais/efeitos dos fármacos , Transfecção , Wortmanina , beta Catenina/metabolismoRESUMO
GPR158 is an orphan G protein-coupled receptor (GPCR) that is broadly expressed in the brain and displays unique structural characteristics and signaling mechanisms. GPR158 is a binding partner for the regulator of G protein signaling 7 (RGS7) and augments its expression, subcellular localization, and catalytic activity. Recent cryo-electron microscopy (cryo-EM) studies have revealed the structure of GPR158 alone and in complex with RGS7. The GPR158-RGS7 complex is shown to be regulated by chronic stress exposure and is a modulator of stress-induced depression. This review highlights the signaling mechanism and function of GPR158-RGS7 and provides a context for the unique formation of GPCR-RGS complexes.
Assuntos
Proteínas RGS , Humanos , Microscopia Crioeletrônica , Proteínas RGS/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais , Membrana Celular/metabolismo , Encéfalo/metabolismoRESUMO
Metabotropic glutamate receptors 2/3 (mGlu(2/3)) have been implicated in schizophrenia and as a novel treatment target for schizophrenia. The current study examined whether mGlu(2/3) regulates Akt (protein kinase B) and Wnt (Wingless/Int-1) signaling, two cascades associated with schizophrenia and modified by antipsychotics. Western blotting revealed increases in phosphorylated Akt (pAkt) and phosphorylated glycogen synthase kinase-3 (pGSK-3) following acute and repeated treatment of LY379268 (mGlu(2/3) agonist), whereas increases in dishevelled-2 (Dvl-2), dishevelled-3 (Dvl-3), GSK-3 and ß-catenin were only observed following repeated treatment. LY341495 (mGlu(2/3) antagonist) induced the opposite response compared with LY379268. Co-immunoprecipitation experiments showed an association between the mGlu(2/3) complex and Dvl-2 providing a possible mechanism to explain how the mGlu(2/3) can mediate changes in Wnt signaling. However, there was no association between the mGlu(2/3) complex and Akt suggesting that changes in Akt signaling following LY341495 and LY379268 treatments may not be directly mediated by the mGlu(2/3) . Finally, an increase in locomotor activity induced by LY341495 treatment correlated with increased pAkt and pGSK-3 levels and was attenuated by the administration of the GSK-3 inhibitor, SB216763. Overall, the results suggest that mGlu(2/3) regulates Akt and Wnt signaling and LY379268 treatment has overlapping effects with D(2) dopamine receptor antagonists (antipsychotic drugs).
Assuntos
Aminoácidos/farmacologia , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Proteínas Proto-Oncogênicas c-akt/fisiologia , Receptores de Glutamato Metabotrópico/agonistas , Receptores de Glutamato Metabotrópico/antagonistas & inibidores , Proteínas Wnt/fisiologia , Xantenos/farmacologia , Animais , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/fisiologia , Quinase 3 da Glicogênio Sintase/antagonistas & inibidores , Masculino , Atividade Motora/efeitos dos fármacos , Córtex Pré-Frontal/efeitos dos fármacos , Córtex Pré-Frontal/fisiologia , Ratos , Ratos Sprague-Dawley , Transdução de SinaisRESUMO
The striatum plays a key role in both reward-related and affective behaviors and disruptions to this circuit contributes to depression and drug addiction. However, our understanding of the molecular factors that facilitate and modify these processes are incomplete. Striatal function is modulated by G-protein-coupled receptors (GPCRs) that process vast neuromodulatory inputs. GPCR signaling is negatively regulated by regulator of G-protein signaling (Rgs) proteins. In this study, we examine the role of striatal Rgs proteins in depressive-like and reward-related behaviors in male mice. Using a genetic mouse model with specific elimination of Rgs7 in striatal neurons we found that these mice exhibit an anxiolytic-like and antidepressant-like phenotype. In contrast, knock-out of Rgs9, an abundant Rgs protein in the same neuronal population did not affect the behavioral outcome in the depressive-like tests. Mice lacking striatal Rgs7 did not show significant differences in cocaine-induced psychomotor activation, sensitization or conditional place preference (CPP). Interestingly, loss of Rgs7 in the striatum made mice resilient to stress-induced but not drug-induced reinstatement of cocaine CPP. Analysis of striatal proteome revealed that loss of Rgs7 selectively affected expression of several networks, most prominently including proteins involved in translation and vesicular exocytosis. Together, these findings begin to demonstrate the specific contribution of Rgs7 acting in the striatum toward depression as it relates to stress-induced reinstatement of drug use.
Assuntos
Cocaína , Proteínas RGS , Animais , Cocaína/farmacologia , Corpo Estriado/metabolismo , Depressão , Masculino , Camundongos , Proteínas RGS/genética , Transdução de SinaisRESUMO
The G protein alpha subunit o (Gαo) is one of the most abundant proteins in the nervous system, and pathogenic mutations in its gene (GNAO1) cause movement disorder. However, the function of Gαo is ill defined mechanistically. Here, we show that Gαo dictates neuromodulatory responsiveness of striatal neurons and is required for movement control. Using in vivo optical sensors and enzymatic assays, we determine that Gαo provides a separate transduction channel that modulates coupling of both inhibitory and stimulatory dopamine receptors to the cyclic AMP (cAMP)-generating enzyme adenylyl cyclase. Through a combination of cell-based assays and rodent models, we demonstrate that GNAO1-associated mutations alter Gαo function in a neuron-type-specific fashion via a combination of a dominant-negative and loss-of-function mechanisms. Overall, our findings suggest that Gαo and its pathological variants function in specific circuits to regulate neuromodulatory signals essential for executing motor programs.
Assuntos
AMP Cíclico/metabolismo , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/metabolismo , Transtornos dos Movimentos/genética , Animais , Humanos , CamundongosRESUMO
Affective disorders arise from abnormal responses of the brain to prolonged exposure to challenging environmental stimuli. Recent work identified the orphan receptor GPR158 as a molecular link between chronic stress and depression. Here we reveal a non-canonical mechanism by which GPR158 exerts its effects on stress-induced depression by the complex formation with Regulator of G protein Signaling 7 (RGS7). Chronic stress promotes membrane recruitment of RGS7 via GPR158 in the medial prefrontal cortex (mPFC). The resultant complex suppresses homeostatic regulation of cAMP by inhibitory GPCRs in the region. Accordingly, RGS7 loss in mice induces an antidepressant-like phenotype and resiliency to stress, whereas its restoration within the mPFC is sufficient to rescue this phenotype in a GPR158-dependent way. These findings mechanistically link the unusual orphan receptor-RGS complex to a major stress mediator, the cAMP system and suggest new avenues for pharmacological interventions in affective disorders.
Assuntos
Comportamento Animal/fisiologia , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Depressão/metabolismo , Homeostase/fisiologia , Córtex Pré-Frontal/metabolismo , Proteínas RGS/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Estresse Psicológico/metabolismo , Animais , Depressão/etiologia , Modelos Animais de Doenças , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Proteínas RGS/deficiência , Estresse Psicológico/complicaçõesRESUMO
Stress can be a motivational force for decisive action and adapting to novel environment; whereas, exposure to chronic stress contributes to the development of depression and anxiety. However, the molecular mechanisms underlying stress-responsive behaviors are not fully understood. Here, we identified the orphan receptor GPR158 as a novel regulator operating in the prefrontal cortex (PFC) that links chronic stress to depression. GPR158 is highly upregulated in the PFC of human subjects with major depressive disorder. Exposure of mice to chronic stress also increased GPR158 protein levels in the PFC in a glucocorticoid-dependent manner. Viral overexpression of GPR158 in the PFC induced depressive-like behaviors. In contrast GPR158 ablation, led to a prominent antidepressant-like phenotype and stress resiliency. We found that GPR158 exerts its effects via modulating synaptic strength altering AMPA receptor activity. Taken together, our findings identify a new player in mood regulation and introduce a pharmacological target for managing depression.
Assuntos
Depressão/fisiopatologia , Regulação da Expressão Gênica , Córtex Pré-Frontal/fisiologia , Receptores Acoplados a Proteínas G/metabolismo , Estresse Psicológico , Animais , Humanos , CamundongosRESUMO
BACKGROUND: Morphine mediates its euphoric and analgesic effects by acting on the µ-opioid receptor (MOR). MOR belongs to the family of G-protein coupled receptors whose signaling efficiency is controlled by the regulator of G-protein signaling (RGS) proteins. Our understanding of the molecular diversity of RGS proteins that control MOR signaling, their circuit specific actions, and underlying cellular mechanisms is very limited. METHODS: We used genetic approaches to ablate regulator of G-protein signaling 7 (RGS7) both globally and in specific neuronal populations. We used conditioned place preference and self-administration paradigms to examine reward-related behavior and a battery of tests to assess analgesia, tolerance, and physical dependence to morphine. Electrophysiology approaches were applied to investigate the impact of RGS7 on morphine-induced alterations in neuronal excitability and plasticity of glutamatergic synapses. At least three animals were used for each assessment. RESULTS: Elimination of RGS7 enhanced reward, increased analgesia, delayed tolerance, and heightened withdrawal in response to morphine administration. RGS7 in striatal neurons was selectively responsible for determining the sensitivity of rewarding and reinforcing behaviors to morphine without affecting analgesia, tolerance, and withdrawal. In contrast, deletion of RGS7 in dopaminergic neurons did not influence morphine reward. RGS7 exerted its effects by controlling morphine-induced changes in excitability of medium spiny neurons in nucleus accumbens and gating the compositional plasticity of α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid and N-methyl-D-aspartate receptors. CONCLUSIONS: This study identifies RGS7 as a novel regulator of MOR signaling by dissecting its circuit specific actions and pinpointing its role in regulating morphine reward by controlling the activity of nucleus accumbens neurons.
Assuntos
Corpo Estriado/fisiologia , Morfina/farmacologia , Proteínas RGS/metabolismo , Recompensa , Transdução de Sinais/efeitos dos fármacos , Animais , Condicionamento Psicológico , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Neurônios Dopaminérgicos/metabolismo , Neurônios Dopaminérgicos/fisiologia , Tolerância a Medicamentos/fisiologia , Feminino , Ácido Glutâmico/fisiologia , Masculino , Camundongos , Camundongos Knockout , Neurônios/fisiologia , Núcleo Accumbens/fisiologia , Medição da Dor/efeitos dos fármacos , Proteínas RGS/genética , Proteínas RGS/fisiologia , Autoadministração , Síndrome de Abstinência a Substâncias/fisiopatologiaRESUMO
It is well recognized that G-protein-coupled receptors (GPCRs) can activate Ras-regulated kinase pathways to produce lasting changes in neuronal function. Mechanisms by which GPCRs transduce these signals and their relevance to brain disorders are not well understood. Here, we identify a major Ras regulator, neurofibromin 1 (NF1), as a direct effector of GPCR signaling via Gßγ subunits in the striatum. We find that binding of Gßγ to NF1 inhibits its ability to inactivate Ras. Deletion of NF1 in striatal neurons prevents the opioid-receptor-induced activation of Ras and eliminates its coupling to Akt-mTOR-signaling pathway. By acting in the striatal medium spiny neurons of the direct pathway, NF1 regulates opioid-induced changes in Ras activity, thereby sensitizing mice to psychomotor and rewarding effects of morphine. These results delineate a novel mechanism of GPCR signaling to Ras pathways and establish a critical role of NF1 in opioid addiction.
Assuntos
Analgésicos Opioides/metabolismo , Neurofibromina 1/genética , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais , Proteínas ras/metabolismo , Animais , Feminino , Masculino , Camundongos , Neostriado/metabolismo , Neurofibromina 1/metabolismo , Neurônios/metabolismo , Ligação ProteicaRESUMO
The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that is involved in neuronal adaptions that underlie cocaine-induced sensitization and reward. mTOR exists in two functionally distinct multi-component complexes known as mTORC1 and mTORC2. In this study, we show that increased mTORC1 activity induced by cocaine is mediated by the dopamine D1 receptor (D1R). Specifically, cocaine treatment increased the phosphorylation on residues Thr2446 and Ser2481 but not on Ser2448 in the nucleus accumbens (NAc) and that this increase in phosphorylated mTOR levels was also apparent when complexed with its binding partner Raptor. Furthermore, the increase in phosphorylated mTOR levels, as well as phosphorylated 4E-BP1 and S6K, downstream targets of mTORC1 were blocked with SCH23390 treatment. Similar results were also observed in the dopamine-transporter knockout mice as the increase in phosphorylated mTOR Thr2446 and Ser2481 was blocked by SCH23390 but not with raclopride. To further validate D1R role in mTORC1 signaling, decrease in phosphorylated mTOR levels were observed in D1R knockout mice, whereas administration of SKF81297 elevated phosphorylated mTOR in the NAc. Lastly deletion of mTOR or Raptor in D1R expressing neurons reduced cocaine-induced locomotor activity. Together, our data supports a mechanism whereby mTORC1 signaling is activated by cocaine administration through the stimulation of D1R.
Assuntos
Cocaína/farmacologia , Inibidores da Captação de Dopamina/farmacologia , Complexos Multiproteicos/metabolismo , Núcleo Accumbens/efeitos dos fármacos , Núcleo Accumbens/metabolismo , Receptores de Dopamina D1/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Benzazepinas/farmacologia , Dopaminérgicos/farmacologia , Proteínas da Membrana Plasmática de Transporte de Dopamina/genética , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Masculino , Alvo Mecanístico do Complexo 1 de Rapamicina , Camundongos Endogâmicos C57BL , Camundongos Knockout , Atividade Motora/efeitos dos fármacos , Atividade Motora/fisiologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Fosforilação/efeitos dos fármacos , Racloprida/farmacologia , Receptores de Dopamina D1/agonistas , Receptores de Dopamina D1/antagonistas & inibidores , Proteína Regulatória Associada a mTOR , Transdução de Sinais/efeitos dos fármacosRESUMO
Protein kinase B (Akt), glycogen synthase kinase-3 (GSK-3) and members of the Wnt signal transduction pathway were recently found to be altered in schizophrenia and targeted by antipsychotic drugs. In the current study, selected Wnt signalling proteins were investigated to determine if they are altered by the antipsychotics clozapine or haloperidol in the rat prefrontal cortex. Pheochromocytoma (PC12) and neuroblastoma (SH-SY5Y) cells were also used to elucidate how antipsychotics generated the pattern of changes observed in vivo. Western blotting (WB) revealed that treatment with haloperidol or clozapine caused an up-regulation of Wnt-5a, dishevelled-3, Axin, total and phosphorylated GSK-3 and beta-catenin protein levels. Treatment of PC12 and SH-SY5Y cells with a variety of pharmacological agents as well as the over-expression of several Wnt related proteins failed to mimic the pattern observed in vivo following antipsychotic treatment. However, the over-expression of dishevelled-3 nearly perfectly duplicated the changes observed in vivo. Immunoprecipitations (IP) conducted using protein isolated from the rat prefrontal cortex indicated that dishevelled-3 is associated with the D2 dopamine receptor thereby suggesting that antipsychotics may act on dishevelled-3 via D2 dopamine receptors to initiate a cascade of downstream changes involving Axin, GSK-3 and beta-catenin that may help to alleviate psychosis in schizophrenic patients.