Validation of dopamine receptor DRD1 and DRD2 antibodies using receptor deficient mice

Environmental enrichment enhances ethanol preference over social reward in male swiss mice: Involvement of oxytocin-dopamine interactions

The impact of environmental enrichment (EE) on natural rewards, including social and appetitive rewards, was investigated in male Swiss mice. EE, known for providing animals with various stimuli, was assessed for its effects on conditioned place preference (CPP) associated with ethanol and social stimuli. We previously demonstrated that EE increased the levels of the prosocial neuropeptide oxytocin (OT) in the hypothalamus and enhanced ethanol rewarding effects via an oxytocinergic mechanism. This study also investigated the impact of EE on social dominance and motivation for rewards, measured OT-mediated phospholipase C (PLC) activity in striatal membranes, and assessed OT expression in the hypothalamus. The role of dopamine in motivating rewards was considered, along with the interaction between OT and D1 receptors (DR) in the nucleus accumbens (NAc). Results showed that EE mice exhibited a preference for ethanol reward over social reward, a pattern replicated by the OT analogue Carbetocin. EE mice demonstrated increased social dominance and reduced motivation for appetitive taste stimuli. Higher OT mRNA levels in the hypothalamus were followed by diminished OT receptor (OTR) signaling activity in the striatum of EE mice. Additionally, EE mice displayed elevated D1R expression, which was attenuated by the OTR antagonist (L-368-889). The findings underscore the reinforcing effect of EE on ethanol and social rewards through an oxytocinergic mechanism. Nonetheless, they suggest that mechanisms other than the prosocial effect of EE may contribute to the ethanol pro-rewarding effect of EE and Carbetocin. They also point towards an OT-dopamine interaction potentially underlying some of these effects.

In need of a specific antibody against the oxytocin receptor for neuropsychiatric research: A KO validation study

Antibodies are one of the most utilized tools in biomedical research. However, few of them are rigorously evaluated, as there are no accepted guidelines or standardized methods for determining their validity before commercialization. Often, an antibody is considered validated if it detects a band by Western blot of the expected molecular weight and, in some cases, if blocking peptides result in loss of staining. Neither of these approaches are unquestionable proof of target specificity. Since the oxytocin receptor has recently become a popular target in neuropsychiatric research, the need for specific antibodies to be used in brain has arisen. In this work, we have tested the specificity of six commercially available oxytocin receptor antibodies, indicated by the manufacturers to be suitable for Western blot and with an available image showing the correct size band (45-55 KDa). Antibodies were first tested by Western blot in brain lysates of wild-type and oxytocin receptor knockout mice. Uterus tissue was also tested as control for putative differential tissue specificity. In brain, the six tested antibodies lacked target specificity, as both wild-type and receptor knockout samples resulted in a similar staining pattern, including the expected 45-55 KDa band. Five of the six antibodies detected a selective band in uterus (which disappeared in knockout tissue). These five specific antibodies were also tested for immunohistochemistry in uterus, where only one was specific. However, when the uterine-specific antibody was tested in brain tissue, it lacked specificity. In conclusion, none of the six tested commercial antibodies are suitable to detect oxytocin receptor in brain by either Western blot or immunohistochemistry, although some do specifically detect it in uterus. The present work highlights the need to develop standardized antibody validation methods, including a proper negative control, in order to grant quality and reproducibility of the generated data.

Parvalbumin interneuron deficiency in the prefrontal and motor cortices of spontaneously hypertensive rats: an attention-deficit hyperactivity disorder animal model insight

Background

Attention deficit hyperactivity disorder (ADHD) is characterized by impairments in developmental-behavioral inhibition, resulting in impulsivity and hyperactivity. Recent research has underscored cortical inhibition deficiencies in ADHD via the gamma-aminobutyric acid (GABA)ergic system, which is crucial for maintaining excitatory-inhibitory balance in the brain. This study explored postnatal changes in parvalbumin (PV) immunoreactivity, indicating GABAergic interneuron types, in the prefrontal (PFC) and motor (MC) cortices of spontaneously hypertensive rats (SHRs), an ADHD animal model.

Methods

Examining PV- positive (PV+) cells associated with dopamine D2 receptors (D2) and the impact of dopamine on GABA synthesis, we also investigated changes in the immunoreactivity of D2 and tyrosine hydroxylase (TH). Brain sections from 4- to 10-week-old SHRs and Wistar Kyoto rats (WKYs) were immunohistochemically analyzed, comparing PV+, D2+ cells, and TH+ fiber densities across age-matched SHRs and WKYs in specific PFC/MC regions.

Results

The results revealed significantly reduced PV+ cell density in SHRs: prelimbic (~20% less), anterior cingulate (~15% less), primary (~15% less), and secondary motor (~17% less) cortices. PV+ deficits coincided with the upregulation of D2 in prepubertal SHRs and the downregulation of TH predominantly in pubertal/postpubertal SHRs.

Conclusion

Reduced PV+ cells in various PFC regions could contribute to inattention/behavioral alterations in ADHD, while MC deficits could manifest as motor hyperactivity. D2 upregulation and TH deficits may impact GABA synthesis, exacerbating behavioral deficits in ADHD. These findings not only shed new light on ADHD pathophysiology but also pave the way for future research endeavors.

Effect of antipsychotic drugs on group II metabotropic glutamate receptor expression and epigenetic control in postmortem brains of schizophrenia subjects

Antipsychotic-induced low availability of group II metabotropic glutamate receptors (including mGlu2R and mGlu3R) in brains of schizophrenia patients may explain the limited efficacy of mGlu2/3R ligands in clinical trials. Studies evaluating mGlu2/3R levels in well-designed, large postmortem brain cohorts are needed to address this issue. Postmortem samples from the dorsolateral prefrontal cortex of 96 schizophrenia subjects and matched controls were collected. Toxicological analyses identified cases who were (AP+) or were not (AP-) receiving antipsychotic treatment near the time of death. Protein and mRNA levels of mGlu2R and mGlu3R, as well as GRM2 and GRM3 promoter-attached histone posttranslational modifications, were quantified. Experimental animal models were used to compare with data obtained in human tissues. Compared to matched controls, schizophrenia cortical samples had lower mGlu2R protein amounts, regardless of antipsychotic medication. Downregulation of mGlu3R was observed in AP- schizophrenia subjects only. Greater predicted occupancy values of dopamine D2 and serotonin 5HT2A receptors correlated with higher density of mGlu3R, but not mGlu2R. Clozapine treatment and maternal immune activation in rodents mimicked the mGlu2R, but not mGlu3R regulation observed in schizophrenia brains. mGlu2R and mGlu3R mRNA levels, and the epigenetic control mechanisms did not parallel the alterations at the protein level, and in some groups correlated inversely. Insufficient cortical availability of mGlu2R and mGlu3R may be associated with schizophrenia. Antipsychotic treatment may normalize mGlu3R, but not mGlu2R protein levels. A model in which epigenetic feedback mechanisms controlling mGlu3R expression are activated to counterbalance mGluR loss of function is described.

Subcutaneous adipose tissue dopamine D2 receptor is increased in prediabetes and T2D

PURPOSE

To evaluate the dopaminergic signaling in human adipose tissue in the context of obesity and type 2 diabetes (T2D) and potential direct implications in adipose tissue metabolism.

METHODS

mRNA and protein expression of dopamine receptors D1 and D2 (DRD1 and DRD2) were determined in subcutaneous adipose tissue from subjects without or with T2D and with different body weight, and correlated with markers of obesity, hyperglycemia, and insulin resistance. Glucose uptake and lipolysis were measured in adipocytes ex vivo following short-term exposure to dopamine, DRD1 receptor agonist (SKF81297), or DRD2 receptor agonist (bromocriptine).

RESULTS

DRD1 and DRD2 gene expression in subcutaneous adipose tissue correlated positively with clinical markers of insulin resistance (e.g. HOMA-IR, insulin, and triglycerides) and central obesity in subjects without T2D. Protein expression of DRD2 in subcutaneous adipose tissue, but not DRD1, is higher in subjects with impaired fasting glucose and T2D and correlated positively with hyperglycemia, HbA1c, and glucose AUC, independent of obesity status. DRD1 and DRD2 proteins were mainly expressed in adipocytes, compared to stromal vascular cells. Dopamine and dopaminergic agonists did not affect adipocyte glucose uptake ex vivo, but DRD1 and DRD2 agonist treatment inhibited isoproterenol-stimulated lipolysis.

CONCLUSION

The results suggest that protein expression of DRD2 in subcutaneous adipose tissue is up-regulated with hyperglycemia and T2D. Whether DRD2 protein levels contribute to T2D development or occur as a secondary compensatory mechanism needs further investigation. Additionally, dopamine receptor agonists inhibit adipocyte beta-adrenergic stimulation of lipolysis, which might contribute to the beneficial effects in lipid metabolism as observed in patients taking bromocriptine.

Boolean analysis shows a high proportion of dopamine D2 receptors interacting with adenosine A2A receptors in striatal medium spiny neurons of mouse and non-human primate models of Parkinson's disease

The antagonistic effect of adenosine on dopaminergic transmission in the basal ganglia indirect motor control pathway is mediated by dopamine D2 (D2R) and adenosine A2A (A2AR) receptors co-expressed on medium spiny striatal neurons. The pathway is unbalanced in Parkinson's disease (PD) and an A2AR blocker has been approved for use with levodopa in the therapy of the disease. However, it is not known whether the therapy is acting on individually expressed receptors or in receptors forming A2A-D2 receptor heteromers, whose functionality is unique. For two proteins prone to interact, a very recently developed technique, MolBoolean, allows to determine the number of proteins that are either non-interacting or interacting. After checking the feasibility of the technique and reliability of data in transfected cells and in striatal primary neurons, the Boolean analysis of receptors in the striatum of rats and monkeys showed a high percentage of D2 receptors interacting with the adenosine receptor, while, on the contrary, a significant proportion of A2A receptors do not interact with dopamine receptors. The number of interacting receptors increased when rats and monkeys were lesioned to become a PD model. The use of a tracer of the indirect pathway in monkeys confirmed that the data was restricted to the population of striatal neurons projecting to the GPe. The results are not only relevant for being the first study quantifying individual versus interacting G protein-coupled receptors, but also for showing that the D2R in these specific neurons, in both control and PD animals, is under the control of the A2AR. The tight adenosine/dopamine receptor coupling suggest benefits of early antiparkinsonian treatment with adenosine receptor blockers.

Dopamine receptors D1 and D2 show prognostic significance and potential therapeutic applications for endometrial cancer patients

OBJECTIVE

Catecholaminergic signaling has been a target for therapy in different type of cancers. In this work, we characterized the ADRβ2, DRD1 and DRD2 expression in healthy tissue and endometrial tumors to evaluate their prognostic significance in endometrial cancer (EC), unraveling their possible application as an antitumor therapy.

METHODS

109 EC patients were included. The expression of the ADRβ2, DRD1 and DRD2 proteins was evaluated by immunohistochemistry and univariate and multivariate analysis to assess their association with clinic-pathological and outcome variables. Finally, HEC1A and AN3CA EC cell lines were exposed to different concentrations of selective dopaminergic agents alone or in combination to study their effects on cellular viability.

RESULTS

ADRβ2 protein expression was not associated with clinico-pathological parameters or prognosis. DRD1 protein expression was reduced in tumors samples but showed a significant inverse association with tumor size and stage. DRD2 protein expression was significantly associated with non-endometrioid EC, high grade tumors, tumor size, worse disease-free survival (HR = 3.47 (95%CI:1.35-8.88)) and overall survival (HR = 2.98 (95%CI:1.40-6.34)). The DRD1 agonist fenoldopam showed a reduction of cellular viability in HEC1A and AN3CA cells. The exposure to domperidone, a DRD2 antagonist, significantly reduced cell viability compared to the control. Finally, DRD1 agonism and DRD2 antagonism combination induced a significant reduction in cell viability of the AN3CA cells compared to monotherapy, close to being an additive response than a synergistic effect (CI of 1.1 at 0.5% Fa).

CONCLUSION

DRD1 and DRD2 expression levels showed a significant association with clinico-pathological parameters. Both the combined activation of DRD1 and blockage of DRD2 may form an innovative strategy to inhibit tumor growth in EC.

Sexual satiety modifies methamphetamine-induced locomotor and rewarding effects and dopamine-related protein levels in the striatum of male rats

RATIONALE

Drug and natural rewarding stimuli activate the mesolimbic dopaminergic system. Both methamphetamine (Meth) and copulation to satiety importantly increase dopamine (DA) release in the nucleus accumbens (NAc), but with differences in magnitude. This paper analyzes the interaction between Meth administration and the intense sexual activity associated with sexual satiety.

OBJECTIVES

To evaluate possible changes in Meth-induced behavioral effects and striatal DA-related protein expression due to sexual satiety.

METHODS

Meth-induced locomotor activity and conditioned place preference (CPP) were tested in sexually experienced male rats that copulated to satiety (S-S) or ejaculated once (1E) the day before or displayed no sexual activity (control group; C). DA receptors and DA transporter expression were determined by western blot in the striatum of animals of all sexual conditions treated with specific Meth doses.

RESULTS

Meth's locomotor and rewarding effects were exacerbated in S-S animals, while in 1E rats, only locomotor effects were enhanced. Sexual activity, by itself, modified DA-related protein expression in the NAc core and in the caudate-putamen (CPu), while Meth treatment alone changed their expression only in the NAc shell. Meth-induced changes in the NAc shell turned in the opposite direction when animals had sexual activity, and additional changes appeared in the NAc core and CPu of S-S rats.

CONCLUSION

Sexual satiety sensitizes rats to Meth's behavioral effects and the Meth-induced striatal DA-related protein adaptations are modified by sexual activity, evidencing cross-sensitization between both stimuli.

Preservation of dendritic D2 receptor transmission in substantia nigra dopamine neurons with age

Substantia nigra pars compacta (SNc) dopamine neurons are required for voluntary movement and reward learning, and advanced age is associated with motor and cognitive decline. In the midbrain, D2-type dopamine receptors located at dendrodendritic synapses between dopamine neurons control cell firing through G protein-activated potassium (GIRK) channels. We previously showed that aging disrupts dopamine neuron pacemaker firing in mice, but only in males. Here we show that the amplitude of D2-receptor inhibitory postsynaptic currents (D2-IPSCs) are moderately reduced in aged male mice. Local application of dopamine revealed a reduction in the amplitude of the D2-receptor currents in old males compared to young, pointing to a postsynaptic mechanism. Further experiments indicated that reduced D2 receptor signaling was not due to a general reduction in GIRK channel currents or degeneration of the dendritic arbor. Kinetic analysis showed no differences in D2-IPSC shape in old versus young mice or between sexes. Potentiation of D2-IPSCs by corticotropin releasing factor (CRF) was also not affected by age, indicating preservation of one mechanism of plasticity. These findings have implications for understanding dopamine transmission in aging, and reduced D2 receptor inhibition could contribute to increased susceptibility of males to SNc dopamine neuron degeneration in Parkinson's disease.

Astrocytes mediate long-lasting synaptic regulation of ventral tegmental area dopamine neurons

The plasticity of glutamatergic transmission in the ventral tegmental area (VTA) represents a fundamental mechanism in the modulation of dopamine neuron burst firing and phasic dopamine release at target regions. These processes encode basic behavioral responses, including locomotor activity, learning and motivated behaviors. Here we describe a hitherto unidentified mechanism of long-term synaptic plasticity in mouse VTA. We found that the burst firing in individual dopamine neurons induces a long-lasting potentiation of excitatory synapses on adjacent dopamine neurons that crucially depends on Ca²⁺ elevations in astrocytes, mediated by endocannabinoid CB1 and dopamine D2 receptors co-localized at the same astrocytic process, and activation of pre-synaptic metabotropic glutamate receptors. Consistent with these findings, selective in vivo activation of astrocytes increases the burst firing of dopamine neurons in the VTA and induces locomotor hyperactivity. Astrocytes play, therefore, a key role in the modulation of VTA dopamine neuron functional activity.

Inverse Salt Sensitivity of Blood Pressure Is Associated with an Increased Renin-Angiotensin System Activity

High and low sodium diets are associated with increased blood pressure and cardiovascular morbidity and mortality. The paradoxical response of elevated BP in low salt diets, aka inverse salt sensitivity (ISS), is an understudied vulnerable 11% of the adult population with yet undiscovered etiology. A linear relationship between the number of single nucleotide polymorphisms (SNPs) in the dopamine D₂ receptor (DRD2, rs6276 and 6277), and the sodium myo-inositol cotransporter 2 (SLC5A11, rs11074656), as well as decreased expression of these two genes in urine-derived renal proximal tubule cells (uRPTCs) isolated from clinical study participants suggest involvement of these cells in ISS. Insight into this newly discovered paradoxical response to sodium is found by incubating cells in low sodium (LS) conditions that unveil cell physiologic differences that are then reversed by mir-485-5p miRNA blocker transfection and bypassing the genetic defect by DRD2 re-expression. The renin-angiotensin system (RAS) is an important counter-regulatory mechanism to prevent hyponatremia under LS conditions. Oversensitive RAS under LS conditions could partially explain the increased mortality in ISS. Angiotensin-II (AngII, 10 nmol/L) increased sodium transport in uRPTCs to a greater extent in individuals with ISS than SR. Downstream signaling of AngII is verified by identifying lowered expression of nuclear factor erythroid 2-related factor 2 (NRF2), CCCTC-binding factor (CTCF), and manganese-dependent mitochondrial superoxide dismutase (SOD2) only in ISS-derived uRPTCs and not SR-derived uRPTCs when incubated in LS conditions. We conclude that DRD2 and SLC5A11 variants in ISS may cause an increased low sodium sensitivity to AngII and renal sodium reabsorption which can contribute to inverse salt-sensitive hypertension.

DOPAMAP, high-resolution images of dopamine 1 and 2 receptor expression in developing and adult mouse brains

The dopaminergic system undergoes major reorganization during development, a period especially vulnerable to mental disorders. Forebrain neurons expressing dopamine 1 and 2 receptors (D1R and D2R, respectively) play a key role in this system. However, neuroanatomical information about the typical development of these neurons is sparse and scattered across publications investigating one or a few brain regions. We here present a public online collection of microscopic images of immunohistochemically stained serial sections from male and female mice at five stages of development (postnatal day 17 (P17), P25, P35, P49, and adult), showing the distribution of D1R and D2R expressing neurons across the forebrain. All images from adult brains are registered to the Allen Mouse brain Common Coordinate Framework, while images from P17-P35 age groups are registered to spatially modified atlas versions matching the morphology of young brains. This online resource provides microscopic visualization of the developing dopaminergic system in mice, which is suitable as a benchmark reference for performing new experiments and building computational models of the brain.

Measurement(s)	mRNA expression
Technology Type(s)	transgenic Mouse • immunohistochemistry staining method
Sample Characteristic - Organism	Mus musculus

Olfactory regulation by dopamine and DRD2 receptor in the nose

Despite the identification of neural circuits and circulating hormones in olfactory regulation, the peripheral targets for olfactory modulation remain relatively unexplored. Here we show that dopamine D2 receptor (DRD2) is expressed in the cilia and somata of mature olfactory sensory neurons (OSNs), while nasal dopamine (DA) is mainly released from the sympathetic nerve terminals, which innervate the mouse olfactory mucosa (OM). We further demonstrate that DA-DRD2 signaling in the nose plays important roles in regulating olfactory function using genetic and pharmacological approaches. Moreover, the local DA synthesis in mouse OM is reduced during hunger, which contributes to starvation-induced olfactory enhancement. Altogether, we demonstrate that nasal DA and DRD2 receptor can serve as the potential peripheral targets for olfactory modulation.

Olfactory behavior is important for animal survival, and olfactory dysfunction is a common feature of several diseases. Despite the identification of neural circuits and circulating hormones in olfactory regulation, the peripheral targets for olfactory modulation remain relatively unexplored. In analyzing the single-cell RNA sequencing data from mouse and human olfactory mucosa (OM), we found that the mature olfactory sensory neurons (OSNs) express high levels of dopamine D2 receptor (Drd2) rather than other dopamine receptor subtypes. The DRD2 receptor is expressed in the cilia and somata of mature OSNs, while nasal dopamine is mainly released from the sympathetic nerve terminals, which innervate the mouse OM. Intriguingly, genetic ablation of Drd2 in mature OSNs or intranasal application with DRD2 antagonist significantly increased the OSN response to odorants and enhanced the olfactory sensitivity in mice. Mechanistic studies indicated that dopamine, acting through DRD2 receptor, could inhibit odor-induced cAMP signaling of olfactory receptors. Interestingly, the local dopamine synthesis in mouse OM is down-regulated during starvation, which leads to hunger-induced olfactory enhancement. Moreover, pharmacological inhibition of local dopamine synthesis in mouse OM is sufficient to enhance olfactory abilities. Altogether, these results reveal nasal dopamine and DRD2 receptor as the potential peripheral targets for olfactory modulation.

An Increase in Peripheral Temperature following Cocaine Administration Is Mediated through Activation of Dopamine D2 Receptor in Rats

Drug addiction has become a worldwide problem, affecting millions of people across the globe. While the majority of mechanistic studies on drug addiction have been focused on the central nervous system, including the mesolimbic dopamine system, the peripheral actions of drugs of abuse remain largely unknown. Our preliminary study found that the systemic injection of cocaine increased peripheral skin temperature. This led us to our present study, which investigated the mechanisms underlying the increase in peripheral temperature following cocaine injection. Male Sprague Dawley rats were anesthetized with pentobarbital sodium, and peripheral skin temperature measurements were taken using a thermocouple needle microprobe and an infrared thermal camera. Cocaine injection caused an acute rise in peripheral body temperature, but not core body temperature, about 10 min after injection, and the temperature increases were occluded by systemic injection of dopamine D2 receptor antagonist L741,626, but not D1 receptor antagonist SCH23390. In addition, systemic administration of bromocriptine, a dopamine D2 receptor agonist, significantly increased peripheral temperature. Infrared thermal imaging showed that the thermal increases following cocaine injection were predominantly in the distal areas of the forelimbs and hindlimbs, relative to core body temperature. Treatment with cocaine or bromocriptine decreased the size of skin blood vessels without affecting the expression of dopamine D2 receptors. These results suggest that increased peripheral temperature in skin following cocaine injection is associated with the activation of the dopamine D2 receptor.

Functionally Antagonistic Transcription Factors IRF1 and IRF2 Regulate the Transcription of the Dopamine Receptor D2 Gene Associated with Aggressive Behavior of Weaned Pigs

Aggressive behavior has negative effects on animal welfare and growth performance in pigs. The dopamine receptor D2 (DRD2) has a critical neuromodulator role in the dopamine signal pathway within the brain to control behavior. A functional single-nucleotide polymorphism (SNP), rs1110730503, in the promoter region of the porcine DRD2 gene was identified, which affects aggressive behavior in pigs. A chromatin immunoprecipitation (ChIP) assay was used to identify the interactions between interferon regulatory factor 1 (IRF1) and IRF2 with the DRD2 gene. The overexpression or knockdown of these two transcription factors in porcine kidney-15 (PK15) and porcine neuronal cells (PNCs) indicate that the binding of IRF1 to DRD2 promotes the transcription of the DRD2 gene, but the binding of IRF2 to the DRD2 gene inhibits its transcription. Furthermore, IRF1 and IRF2 are functionally antagonistic to each other. The downregulation of DRD2 or upregulation of IRF2 increased the apoptosis rate of porcine neuroglial cells. Taken together, we found that transcriptional factors IRF1 and IRF2 have vital roles in regulating the transcription of the DRD2 gene, and rs1110730503 (−915A/T) is a functional SNP that influences IRF2 binding to the promoter of the DRD2 gene. These findings will provide further insight towards controlling aggressive behavior in pigs.

Dose Effects of Histone Deacetylase Inhibitor Tacedinaline (CI-994) on Antipsychotic Haloperidol-Induced Motor and Memory Side Effects in Aged Mice

Background: Elderly patients treated with antipsychotic drugs often experience increased severity and frequency of side effects, yet the mechanisms are not well understood. Studies from our group indicate age-related histone modifications at drug targeted receptor gene promoters may contribute to the increased side effects, and histone deacetylase (HDAC) inhibitors entinostat (MS-275) and valproic acid (VPA) could reverse typical antipsychotic haloperidol (HAL) induced motor-side effects. However, whether such effects could be dose dependent and whether HDAC inhibitors could improve memory function in aged mice is unknown. Methods: We co-treated selective class 1 HDAC inhibitor tacedinaline (CI-994) at different doses (10, 20, and 30 mg/kg) with HAL (0.05 mg/kg) in young (3 months) and aged (21 months) mice for 14 consecutive days, then motor and memory behavioral tests were conducted, followed by biochemical measurements. Results: CI-994 at doses of 10 and 20 mg/kg could decrease HAL-induced cataleptic episodes but only 20 mg/kg was sufficient to improve motor coordination in aged mice. Additionally, CI-994 at 10 and 20 mg/kg mitigate HAL-induced memory impairment in aged mice. Biochemical analyses showed increased acetylation of histone marks H3K27ac and H3K18ac at the dopamine 2 receptor (D2R) gene (Drd2) promoter and increased expression of the Drd2 mRNA and D2R protein in the striatum of aged mice after administration of CI-994 at 20 mg/kg. Conclusions: Our results suggest CI-994 can reduce HAL-induced motor and memory side effects in aged mice. These effects may act through an increase of acetylation at the Drd2 promoter, thereby restoring D2R expression and improving antipsychotic drug action.

FFAR1/GPR40 Contributes to the Regulation of Striatal Monoamine Releases and Facilitation of Cocaine-Induced Locomotor Activity in Mice

The free fatty acid receptor 1 (FFAR1) is suggested to function as a G protein-coupled receptor (GPR40) for medium-to-long-chain free fatty acids. Previous studies on the expression of FFAR1 revealed that the nigrostriatal region is one of the areas which express abundant FFAR1 mRNA/protein in the central nervous system (CNS). However, the role of FFAR1 in the CNS has been still largely unclarified. Here, we examined a possible functional role of FFAR1 in the control of extracellular concentrations of striatal monoamines and cocaine-induced locomotor activity. Microdialysis analysis revealed that the basal level of extracellular dopamine (DA) was significantly elevated, while the basal serotonin (5-HT) level tended to be reduced in the striatum of FFAR1 knockout (-/-) mice. Interestingly, local application of a FFAR1 agonist, GW9508, markedly augmented the striatal 5-HT release in FFAR1 wild-type (+/+) mice, whereas topical application of a FFAR1 antagonist, GW1100, significantly reduced the 5-HT release. However, the enhanced 5-HT release was completely lost in -/- mice. Although acute administration of cocaine enhanced the locomotor activity in both +/+ and -/- mice, the magnitude of the enhancement was significantly reduced in -/- mice. In addition, intraperitoneal injection of GW1100 significantly decreased the cocaine-induced locomotor enhancement. These results suggest that FFAR1 has a facilitatory role in striatal 5-HT release, and the evoked 5-HT release might contribute to enhance cocaine-induced locomotor activity.

The difficulty to model Huntington's disease in vitro using striatal medium spiny neurons differentiated from human induced pluripotent stem cells

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by an expanded polyglutamine repeat in the huntingtin gene. The neuropathology of HD is characterized by the decline of a specific neuronal population within the brain, the striatal medium spiny neurons (MSNs). The origins of this extreme vulnerability remain unknown. Human induced pluripotent stem cell (hiPS cell)-derived MSNs represent a powerful tool to study this genetic disease. However, the differentiation protocols published so far show a high heterogeneity of neuronal populations in vitro. Here, we compared two previously published protocols to obtain hiPS cell-derived striatal neurons from both healthy donors and HD patients. Patch-clamp experiments, immunostaining and RT-qPCR were performed to characterize the neurons in culture. While the neurons were mature enough to fire action potentials, a majority failed to express markers typical for MSNs. Voltage-clamp experiments on voltage-gated sodium (Nav) channels revealed a large variability between the two differentiation protocols. Action potential analysis did not reveal changes induced by the HD mutation. This study attempts to demonstrate the current challenges in reproducing data of previously published differentiation protocols and in generating hiPS cell-derived striatal MSNs to model a genetic neurodegenerative disorder in vitro.

Activation of the basal ganglia and indirect pathway neurons during frontal lobe seizures

There are no detailed descriptions of neuronal circuit active during frontal lobe motor seizures. Using activity reporter mice, local field potential recordings, tissue clearing, viral tracing, and super-resolution microscopy, we found neuronal activation after focal motor to bilateral tonic-clonic seizures in the striatum, globus pallidus externus, subthalamic nucleus, substantia nigra pars reticulata and neurons of the indirect pathway. Seizures preferentially activated dopamine D2 receptor-expressing neurons over D1 in the striatum, which have different projections. Furthermore, the D2 receptor agonist infused into the striatum exerted an anticonvulsant effect. Seizures activate structures via short and long latency loops, and anatomical connections of the seizure focus determine the seizure circuit. These studies, for the first time, show activation of neurons in the striatum, globus pallidus, subthalamic nucleus, and substantia nigra during frontal lobe motor seizures on the cellular level, revealing a complex neuronal activation circuit subject to modulation by the basal ganglia.

Nicotine abolishes memory-related synaptic strengthening and promotes synaptic depression in the neurogenic dentate gyrus of miR-132/212 knockout mice

Micro-RNAs (miRNAs) are highly evolutionarily conserved short-length/noncoding RNA molecules that modulate a wide range of cellular functions in many cell types by regulating the expression of a variety of targeted genes. miRNAs have also recently emerged as key regulators of neuronal genes mediating the effects of psychostimulant drugs and memory-related neuroplasticity processes. Smoking is a predominant addictive behaviour associated with millions of deaths worldwide, and nicotine is a potent natural psychoactive agonist of cholinergic receptors, highly abundant in cigarettes. The influence of miRNAs modulation on cholinergic signalling in the nervous system remains however poorly explored. Using miRNA knockout mice and biochemical, electrophysiological and pharmacological approaches, we examined the effects of miR-132/212 gene disruption on the levels of hippocampal nicotinic acetylcholine receptors, total ERK and phosphorylated ERK (pERK) and MeCP2 protein levels, and studied the impact of nicotine stimulation on hippocampal synaptic transmission and synaptic depression and strengthening. miR-132/212 deletion significantly altered α7-nAChR and pERK protein levels, but not total ERK or MeCP2, and resulted in both exacerbated synaptic depression and virtually abolished memory-related synaptic strengthening upon nicotine stimulation. These observations reveal a functional miRNAs/nicotinergic signalling interplay critical for nicotinic-receptor expression and neuroplasticity in brain structures relevant for drug addiction and learning and memory functions.

Dopamine receptor D1- and D2-agonists do not spark brown adipose tissue thermogenesis in mice

Brown adipose tissue (BAT) thermogenesis is considered a potential target for treatment of obesity and diabetes. In vitro data suggest dopamine receptor signaling as a promising approach; however, the biological relevance of dopamine receptors in the direct activation of BAT thermogenesis in vivo remains unclear. We investigated BAT thermogenesis in vivo in mice using peripheral administration of D1-agonist SKF38393 or D2-agonist Sumanirole, infrared thermography, and in-depth molecular analyses of potential target tissues; and ex vivo in BAT explants to identify direct effects on key thermogenic markers. Acute in vivo treatment with the D1- or D2-agonist caused a short spike or brief decrease in BAT temperature, respectively. However, repeated daily administration did not induce lasting effects on BAT thermogenesis. Likewise, neither agonist directly affected Ucp1 or Dio2 mRNA expression in BAT explants. Taken together, the investigated agonists do not seem to exert lasting and physiologically relevant effects on BAT thermogenesis after peripheral administration, demonstrating that D1- and D2-receptors in iBAT are unlikely to constitute targets for obesity treatment via BAT activation.

Molecular repertoire of Deinococcus radiodurans after 1 year of exposure outside the International Space Station within the Tanpopo mission

BACKGROUND

The extraordinarily resistant bacterium Deinococcus radiodurans withstands harsh environmental conditions present in outer space. Deinococcus radiodurans was exposed for 1 year outside the International Space Station within Tanpopo orbital mission to investigate microbial survival and space travel. In addition, a ground-based simulation experiment with conditions, mirroring those from low Earth orbit, was performed.

METHODS

We monitored Deinococcus radiodurans cells during early stage of recovery after low Earth orbit exposure using electron microscopy tools. Furthermore, proteomic, transcriptomic and metabolomic analyses were performed to identify molecular mechanisms responsible for the survival of Deinococcus radiodurans in low Earth orbit.

RESULTS

D. radiodurans cells exposed to low Earth orbit conditions do not exhibit any morphological damage. However, an accumulation of numerous outer-membrane-associated vesicles was observed. On levels of proteins and transcripts, a multi-faceted response was detected to alleviate cell stress. The UvrABC endonuclease excision repair mechanism was triggered to cope with DNA damage. Defense against reactive oxygen species is mirrored by the increased abundance of catalases and is accompanied by the increased abundance of putrescine, which works as reactive oxygen species scavenging molecule. In addition, several proteins and mRNAs, responsible for regulatory and transporting functions showed increased abundances. The decrease in primary metabolites indicates alternations in the energy status, which is needed to repair damaged molecules.

CONCLUSION

Low Earth orbit induced molecular rearrangements trigger multiple components of metabolic stress response and regulatory networks in exposed microbial cells. Presented results show that the non-sporulating bacterium Deinococcus radiodurans survived long-term low Earth orbit exposure if wavelength below 200 nm are not present, which mirrors the UV spectrum of Mars, where CO₂ effectively provides a shield below 190 nm. These results should be considered in the context of planetary protection concerns and the development of new sterilization techniques for future space missions. Video Abstract.

Selective Effects of Thioridazine on Self-Renewal of Basal-Like Breast Cancer Cells

Several recent publications demonstrated that DRD2-targeting antipsychotics such as thioridazine induce proliferation arrest and apoptosis in diverse cancer cell types including those derived from brain, lung, colon, and breast. While most studies show that 10–20 µM thioridazine leads to reduced proliferation or increased apoptosis, here we show that lower doses of thioridazine (1–2 µM) target the self-renewal of basal-like breast cancer cells, but not breast cancer cells of other subtypes. We also show that all breast cancer cell lines tested express DRD2 mRNA and protein, regardless of thioridazine sensitivity. Further, DRD2 stimulation with quinpirole, a DRD2 agonist, promotes self-renewal, even in cell lines in which thioridazine does not inhibit self-renewal. This suggests that DRD2 is capable of promoting self-renewal in these cell lines, but that it is not active. Further, we show that dopamine can be detected in human and mouse breast tumor samples. This observation suggests that dopamine receptors may be activated in breast cancers, and is the first time to our knowledge that dopamine has been directly detected in human breast tumors, which could inform future investigation into DRD2 as a therapeutic target for breast cancer.

Dosage sensitivity intolerance of VIPR2 microduplication is disease causative to manifest schizophrenia-like phenotypes in a novel BAC transgenic mouse model

Recent genome-wide association studies (GWAS) have identified copy number variations (CNVs) at chromosomal locus 7q36.3 that significantly contribute to the risk of schizophrenia, with all of the microduplications occurring within a single gene: vasoactive intestinal peptide receptor 2 (VIPR2). To confirm disease causality and translate such a genetic vulnerability into mechanistic and pathophysiological insights, we have developed a series of conditional VIPR2 bacterial artificial chromosome (BAC) transgenic mouse models of VIPR2 CNV. VIPR2 CNV mouse model recapitulates gene expression and signaling deficits seen in human CNV carriers. VIPR2 microduplication in mice elicits prominent dorsal striatal dopamine dysfunction, cognitive, sensorimotor gating, and social behavioral deficits preceded by an increase of striatal cAMP/PKA signaling and the disrupted early postnatal striatal development. Genetic removal of VIPR2 transgene expression via crossing with Drd1a-Cre BAC transgenic mice rescued the dopamine D2 receptor abnormality and multiple behavioral deficits, implicating a pathogenic role of VIPR2 overexpression in dopaminoceptive neurons. Thus, our results provide further evidence to support the GWAS studies that the dosage sensitivity intolerance of VIPR2 is disease causative to manifest schizophrenia-like dopamine, cognitive, and social behavioral deficits in mice. The conditional BAC transgenesis offers a novel strategy to model CNVs with a gain-of -copies and facilitate the genetic dissection of when/where/how the genetic vulnerabilities affect development, structure, and function of neural circuits. Our findings have important implications for therapeutic development, and the etiology-relevant mouse model provides a useful preclinical platform for drug discovery.

Cancer and the Dopamine D2 Receptor: A Pharmacological Perspective

The dopamine D₂ receptor (D₂R) family is upregulated in many cancers and tied to stemness. Reduced cancer risk has been correlated with disorders such as schizophrenia and Parkinson's disease, in which dopaminergic drugs are used. D₂R antagonists are reported to have anticancer efficacy in cell culture and animal models where they have reduced tumor growth, induced autophagy, affected lipid metabolism, and caused apoptosis, among other effects. This has led to several hypotheses, the most prevalent being that D₂R ligands may be a novel approach to cancer chemotherapy. This hypothesis is appealing because of the large number of approved and experimental drugs of this class that could be repurposed. We review the current state of the literature and the evidence for and against this hypothesis. When the existing literature is evaluated from a pharmacological context, one of the striking findings is that the concentrations needed for cytotoxic effects of D₂R antagonists are orders of magnitude higher than their affinity for this receptor. Although additional definitive studies will provide further clarity, our hypothesis is that targeting D₂-like dopamine receptors may only yield useful ligands for cancer chemotherapy in rare cases.

Spheroid glioblastoma culture conditions as antigen source for dendritic cell-based immunotherapy: spheroid proteins are survival-relevant targets but can impair immunogenic interferon γ production

BACKGROUND

Glioblastoma is the most aggressive type of brain cancer. Dendritic cell (DC)-based immunotherapy against glioblastoma depends on the effectiveness of loaded antigens. Sphere-inducing culture conditions are being studied by many as a potential antigen source. Here, we investigated two different in vitro conditions (spheroid culture versus adherent culture) in relation to DC immunotherapy: (1) We studied the specific spheroid-culture proteome and assessed the clinical importance of spheroid proteins. (2) We evaluated the immunogenicity of spheroid lysate - both compared to adherent conditions.

METHODS

We used seven spheroid culture systems, three of them patient-derived. Stemness-related markers were studied in those three via immunofluorescence. Spheroid-specific protein expression was measured via quantitative proteomics. The Cancer Genome Atlas (TCGA) survival data was used to investigate the clinical impact of spheroid proteins. Immunogenicity of spheroid versus adherent cell lysate was explored in autologous ELISPOT systems (DCs and T cells from the three patients).

RESULTS

(1) The differential proteome of spheroid versus adherent glioblastoma culture conditions could successfully be established. The top 10 identified spheroid-specific proteins were associated with significantly decreased overall survival (TCGA MIT/Harvard cohort; n = 350, P = 0.014). (2) In exploratory experiments, immunogenicity of spheroid lysate vis-á-vis interferon (IFN)γ production was lower than that of adherent cell lysate (IFNγ ELISPOT; P = 0.034).

CONCLUSIONS

Spheroid culture proteins seem to represent survival-relevant targets, supporting the use of spheroid culture conditions as an antigen source for DC immunotherapy. However, immunogenicity enhancement should be considered for future research. Transferability of our findings in terms of clinical impact and regarding different spheroid-generation techniques needs further validation.

Genetic labeling reveals temporal and spatial expression pattern of D2 dopamine receptor in rat forebrain

The D2 dopamine receptor (Drd2) is implicated in several brain disorders such as schizophrenia, Parkinson’s disease, and drug addiction. Drd2 is also the primary target of both antipsychotics and Parkinson’s disease medications. Although the expression pattern of Drd2 is relatively well known in mouse brain, the temporal and spatial distribution of Drd2 is lesser clear in rat brain due to the lack of Drd2 reporter rat lines. Here, we used CRISPR/Cas9 techniques to generate two knockin rat lines: Drd2::Cre and Rosa26::loxp-stop-loxp-tdTomato. By crossing these two lines, we produced Drd2 reporter rats expressing the fluorescence protein tdTomato under the control of the endogenous Drd2 promoter. Using fluorescence imaging and unbiased stereology, we revealed the cellular expression pattern of Drd2 in adult and postnatal rat forebrain. Strikingly, the Drd2 expression pattern differs between Drd2 reporter rats and Drd2 reporter mice generated by BAC transgene in prefrontal cortex and hippocampus. These results provide fundamental information needed for the study of Drd2 function in rat forebrain. The Drd2::Cre rats generated here may represent a useful tool to study the function of neuronal populations expressing Drd2.

A proteotranscriptomic study of silk-producing glands from the orb-weaving spiders

A proteotranscriptomic approach provides a biochemical basis for understanding the intricate spinning process and complex structural features of spider silk proteins.

A fresh look at cortical dopamine D2 receptor expressing neurons

The dopamine D2 receptor (DRD2) remains the principal target of antipsychotic drugs used for the management of schizophrenia and other psychotic disorders. This receptor is highly expressed within the basal ganglia, more specifically the striatal caudate nucleus and the nucleus accumbens. The general functions, signaling and behavioral contributions of striatal DRD2 are well understood. However, the study of cortical DRD2 expression and functions has for the most part been restricted to a subset of pyramidal neurons and interneurons (e.g. parvalbumine positive) of the pre frontal cortex where DRD2 regulated local circuits are believed to contribute to the regulation of emotional and cognitive functions. The further investigations of cortical DRD2 functions have been hindered by relatively low receptor expression and the sensitivity of detection methods. Here we report recent findings by our group using high sensitivity approaches to map cortical DRD2 expression. Results from these investigations revealed different scales of heterogeneity within DRD2 expressing neurons. These variations affected the types of neurons expressing DRD2 as well as the co-expression of DRD2 with other receptors across several cortical regions. Furthermore several cortical regions showing higher clusters of DRD2 expressing neurons are involved in the regulation of emotional, cognitive and sensory functions that can be involved in the expression of psychotic symptoms. These findings underscore the need for a reexamination of cortical DRD2 mediated synaptic plasticity in the context of schizophrenia and other psychotic disorders.

Thioridazine inhibits self-renewal in breast cancer cells via DRD2-dependent STAT3 inhibition, but induces a G1 arrest independent of DRD2

Thioridazine is an antipsychotic that has been shown to induce cell death and inhibit self-renewal in a broad spectrum of cancer cells. The mechanisms by which these effects are mediated are currently unknown but are presumed to result from the inhibition of dopamine receptor 2 (DRD2). Here we show that the self-renewal of several, but not all, triple-negative breast cancer cell lines is inhibited by thioridazine. The inhibition of self-renewal by thioridazine in these cells is mediated by DRD2 inhibition. Further, we demonstrate that DRD2 promotes self-renewal in these cells via a STAT3- and IL-6-dependent mechanism. We also show that thioridazine induces a G1 arrest and a loss in cell viability in all tested cell lines. However, the reduction in proliferation and cell viability is independent of DRD2 and STAT3. Our results indicate that although there are cell types in which DRD2 inhibition results in inhibition of STAT3 and self-renewal, the dramatic block in cancer cell proliferation across many cell lines caused by thioridazine treatment is independent of DRD2 inhibition.

Transgenerational transmission of hedonic behaviors and metabolic phenotypes induced by maternal overnutrition

Maternal overnutrition has been associated with increased susceptibility to develop obesity and neurological disorders later in life. Most epidemiological as well as experimental studies have focused on the metabolic consequences across generations following an early developmental nutritional insult. Recently, it has been shown that maternal high-fat diet (HFD) affects third-generation female body mass via the paternal lineage. We showed here that the offspring born to HFD ancestors displayed addictive-like behaviors as well as obesity and insulin resistance up to the third generation in the absence of any further exposure to HFD. These findings, implicate that the male germ line is a major player in transferring phenotypic traits. These behavioral and physiological alterations were paralleled by reduced striatal dopamine levels and increased dopamine 2 receptor density. Interestingly, by the third generation a clear gender segregation emerged, where females showed addictive-like behaviors while male HFD offspring showed an obesogenic phenotype. However, methylome profiling of F1 and F2 sperm revealed no significant difference between the offspring groups, suggesting that the sperm methylome might not be the major carrier for the transmission of the phenotypes observed in our mouse model. Together, our study for the first time demonstrates that maternal HFD insult causes sustained alterations of the mesolimbic dopaminergic system suggestive of a predisposition to develop obesity and addictive-like behaviors across multiple generations.

Proteomic Studies on the Swim Bladder of the European Eel (Anguilla anguilla)

The swim bladder of a fish is a vital organ that with gas gland cells in the swim bladder wall enables key physiological functions including buoyancy regulation in the face of different hydrostatic pressures. Specific gas gland cells produce and secrete acidic metabolites into the blood in order to reduce the physical solubility of gases and blood gas transport capacity for regulating the volume of the swim bladder. Transcriptomic analyses have provided evidence at the RNA level but no specific studies at the protein level have been carried out so far. Herein, it was the aim of the study to show swim bladder proteins of the yellow stage European eel by label-free LCMS (Q-Exactive Plus) that resulted in the identification of 6223 protein groups. Neurotransmitter receptors and transporters were enriched in the membrane fraction and enzymes for acid production were observed. The list of identified proteins may represent a useful tool for further proteomics experiments on this organ. All MS proteomics data are available at the PRIDE repository with the dataset identifier PXD007850.

Dopamine receptors in the rat entopeduncular nucleus

Dopamine is critical for the normal functioning of the basal ganglia, modulating both input and output nuclei of this system. The distribution and function of each of the five dopamine receptor subtypes have been studied extensively in the striatum. However, the role of extrastriatal dopamine receptors in basal ganglia information processing is less clear. Here, we studied the anatomical distribution of dopamine receptors in one of the output nuclei of the rodent basal ganglia, the entopeduncular nucleus (EP). The presence of all dopamine receptor subtypes was verified in the EP using immunostaining. We detected co-localization of dopamine receptors with VGAT, which suggests presynaptic expression on GABAergic terminals. D1R and D2R were strongly colocalized with VGAT, whereas DR3-5 showed only sparse co-localization. We further labeled striatal or pallidal neurons with GFP and showed that only D1 receptors were co-localized with striatal terminals, while only D2R and D3R were co-localized with pallidal terminals. Dopamine receptors were also strongly co-localized with MAP2, indicating postsynaptic expression. Overall, these findings suggest that the dopaminergic system modulates activity in the EP both directly via postsynaptic receptors, and indirectly via GABAergic synapses stemming from the direct and indirect pathways.

α1b-Adrenergic Receptor Localization and Relationship to the D1-Dopamine Receptor in the Rat Nucleus Accumbens

The α1-adrenergic receptors (α1ARs) have been implicated in numerous actions of the brain, including attention and wakefulness. Additionally, they have been identified as contributing to disorders of the brain, such as drug addiction, and recent work has shown a role of these receptors in relapse to psychostimulants. While some functionality is known, the actual subcellular localization of the subtypes of the α1ARs remains to be elucidated. Further, their anatomical relationship to receptors for other neurotransmitters, such as dopamine (DA), remains unclear. Therefore, using immunohistochemistry and electron microscopy techniques, this study describes the subcellular localization of the α1b-adrenergic receptor (α1bAR), the subtype most tied to relapse behaviors, as well as its relationship to the D1-dopamine receptor (D1R) in both the shell and core of the rat nucleus accumbens (NAc). Overall, α1bARs were found in unmyelinated axons and axon terminals with some labeling in dendrites. In accordance with other studies of the striatum, the D1R was found mainly in dendrites and spines; therefore, colocalization of the D1R with the α1bAR was rare postsynaptically. However, in the NAc shell, when the receptors were co-expressed in the same neuronal elements there was a trend for both receptors to be found on the plasma membrane, as opposed to the intracellular compartment. This study provides valuable anatomical information about the α1bAR and its relationship to the D1R and the regulation of DA and norepinephrine (NE) neurotransmission in the brain which have been examined previously.

Quantitative Proteomics of Synaptosomal Fractions in a Rat Overexpressing Human DISC1 Gene Indicates Profound Synaptic Dysregulation in the Dorsal Striatum

Disrupted-in-schizophrenia 1 (DISC1) is a key protein involved in behavioral processes and various mental disorders, including schizophrenia and major depression. A transgenic rat overexpressing non-mutant human DISC1, modeling aberrant proteostasis of the DISC1 protein, displays behavioral, biochemical and anatomical deficits consistent with aspects of mental disorders, including changes in the dorsal striatum, an anatomical region critical in the development of behavioral disorders. Herein, dorsal striatum of 10 transgenic DISC1 (tgDISC1) and 10 wild type (WT) littermate control rats was used for synaptosomal preparations and for performing liquid chromatography-tandem mass spectrometry (LC-MS)-based quantitative proteomics, using isobaric labeling (TMT10plex). Functional enrichment analysis was generated from proteins with level changes. The increase in DISC1 expression leads to changes in proteins and synaptic-associated processes including membrane trafficking, ion transport, synaptic organization and neurodevelopment. Canonical pathway analysis assigned proteins with level changes to actin cytoskeleton, Gαq, Rho family GTPase and Rho GDI, axonal guidance, ephrin receptor and dopamine-DARPP32 feedback in cAMP signaling. DISC1-regulated proteins proposed in the current study are also highly associated with neurodevelopmental and mental disorders. Bioinformatics analyses from the current study predicted that the following biological processes may be activated by overexpression of DISC1, i.e., regulation of cell quantities, neuronal and axonal extension and long term potentiation. Our findings demonstrate that the effects of overexpression of non-mutant DISC1 or its misassembly has profound consequences on protein networks essential for behavioral control. These results are also relevant for the interpretation of previous as well as for the design of future studies on DISC1.