Animal Model Of Schizophrenia Research Articles

Simultaneous activation of muscarinic and GABAB receptors as a bidirectional target for novel antipsychotics

Recent preclinical studies point to muscarinic and GABAB receptors as novel therapeutic targets for the treatment of schizophrenia. This study was aimed to assess the role of muscarinic and GABAB receptor interactions in animal models of schizophrenia, using positive allosteric modulators (PAMs) of GABAB receptor (GS39783), muscarinic M4 (VU0152100) and M5 (VU0238429) receptor, and partial allosteric agonist of M1 receptor (VU0357017).DOI-induced head twitches, social interaction and novel object recognition tests were used as the models of schizophrenia. Analyses of DOI-induced increases in sEPSCs (spontaneous excitatory postsynaptic currents) were performed as complementary experiments to the DOI-induced head twitch studies. Haloperidol-induced catalepsy and the rotarod test were used to examine the adverse effects of the drugs.All three activators of muscarinic receptors were active in DOI-induced head twitches. When administered together with GS39783 in subeffective doses, only the co-administration of VU0152100 and GS39783 was effective. The combination also reduced the frequency but not the amplitude of DOI-induced sEPSCs. Neither VU0357017 nor VU0238429 were active in social interaction test when given alone, and also the combination of VU0152100 and GS39783 failed to reverse MK-801-induced deficits observed in this test. All muscarinic activators when administered alone or in combination with GS39783 reversed the MK-801-induced disruption of memory in the novel object recognition test, and their actions were blocked by specific antagonists. None of the tested compounds or their combinations influenced the motor coordination of the animals. The compounds had no effect on haloperidol-induced catalepsy and did not induce catalepsy when administered alone. Pharmacokinetic analysis confirmed lack of possible drug-drug interactions after combined administration of GS39783 with VU0357017 or VU0152100; however, when the drug was co-administered with VU0238429 its ability to pass the blood-brain barrier slightly decreased, suggesting potential drug-drug interactions.Our data show that modulation of cholinergic and GABAergic systems can potentially be beneficial in the treatment of the positive and cognitive symptoms of schizophrenia without inducing the adverse effects typical for presently used antipsychotics.

Negative Allosteric Modulators of mGlu7 Receptor as Putative Antipsychotic Drugs.

The data concerning antipsychotic-like activity of negative allosteric modulators (NAMs)/antagonists of mGlu7 receptors are limited. The only available ligands for this receptor are MMPIP and ADX71743. In the present studies, we used stable cell line expressing mGlu7 receptor and it was shown that both compounds dose-dependently potentiated forskolin elevated cAMP concentration in the T-REx 293 cells, showing their inverse agonist properties. Subsequently, pharmacokinetic studies were performed. Both compounds were given intraperitoneally (i.p.) at the dose of 10 mg/kg and reached Cmax 0.25–0.5 h after administration, and then they declined rapidly, ADX71743 being almost undetectable 2 h after administration, while the concentration of MMPIP was still observed, suggesting that the concentration of MMPIP was more stable. Finally, we investigated the role of both mGlu7 receptor NAMs in animal models of schizophrenia. Behavioral tests commonly used in antipsychotic drug discovery were conducted. Both tested compounds dose-dependently inhibited MK-801-induced hyperactivity (MMPIP at 15 mg/kg; ADX at 5 and 15 mg/kg) and DOI-induced head twitches (MMPIP at 5, 10, 15 mg/kg; ADX at 2.5, 5, 10 mg/kg). Moreover, the same effects were noticed in novel object recognition test, where MMPIP (5, 10, 15 mg/kg) and ADX71743 (1, 5, 15 mg/kg) reversed MK-801-induced disturbances. In the social interaction test, antipsychotic activity was observed only for ADX71743 (5, 15 mg/kg). ADX71743 at the dose 2.5 mg/kg reversed MK-801-induced disruption in prepulse inhibition while MMPIP at 10 mg/kg reversed MK-801-induced disruption in spatial delayed alternation. The present studies showed that mGlu7 receptor may be considered as a putative target for antipsychotic drugs, though more studies are needed due to limited number of available ligands.

Dissociated features of social cognition altered in mouse models of schizophrenia: Focus on social dominance and acoustic communication

Social and communication impairments are common features of psychiatric disorders. Animal models of schizophrenia display various social deficits due to difference in tests, mouse strains and drugs. Moreover, communication deficits have not been studied. Our objectives were to assess and compare three major features of social cognition in different mouse models of schizophrenia: interest for a social stimulus, organization and acceptance of social contact, and acoustic communication to question whether mouse models for schizophrenia with social dysfunction also exhibit vocal communication defects.To achieve these aims we treated acutely C57BL/6J mice either with MK-801 or ketamine and tested WT and microtubule-associated protein 6 -MAP6- KO mice in two complementary social tasks: the 3-chamber test which measures social motivation and the social interaction task –SIT- which relies on prefrontal cortex activity and measures the ability to organize and respond to a real interaction, and which promotes ultrasonic vocalizations.Our results reveal that schizophrenia models have intact interest for a social stimulus in the 3-chamber test. However, thanks to principal component analyses of social interaction data, we demonstrate that social motivation and the ability to act socially rely on distinct mechanisms in revealing a decrease in dominance and communication in pharmacological schizophrenia models along with social withdraw, classically observed in schizophrenia, in MK-801 model. In this latter model, some social parameters can be significantly improved by aripiprazole, an atypical antipsychotic. Our social protocol, combined with fine-tuned analysis, is expected to provide an innovative framework for testing future treatments in preclinical models.This article is part of the Special Issue entitled ‘The neuropharmacology of social behavior: from bench to bedside’.

Behavioral and Neural Changes in Early Visual Processing in an Animal Model of Schizophrenia

Behavioral and Neural Changes in Early Visual Processing in an Animal Model of Schizophrenia

CAMP Response Element-Binding Protein (CREB): A Possible Signaling Molecule Link in the Pathophysiology of Schizophrenia.

Dopamine is a brain neurotransmitter involved in the pathology of schizophrenia. The dopamine hypothesis states that, in schizophrenia, dopaminergic signal transduction is hyperactive. The cAMP-response element binding protein (CREB) is an intracellular protein that regulates the expression of genes that are important in dopaminergic neurons. Dopamine affects the phosphorylation of CREB via G protein-coupled receptors. Neurotrophins, such as brain derived growth factor (BDNF), are critical regulators during neurodevelopment and synaptic plasticity. The CREB is one of the major regulators of neurotrophin responses since phosphorylated CREB binds to a specific sequence in the promoter of BDNF and regulates its transcription. Moreover, susceptibility genes associated with schizophrenia also target and stimulate the activity of CREB. Abnormalities of CREB expression is observed in the brain of individuals suffering from schizophrenia, and two variants (-933T to C and -413G to A) were found only in schizophrenic patients. The CREB was also involved in the therapy of animal models of schizophrenia. Collectively, these findings suggest a link between CREB and the pathophysiology of schizophrenia. This review provides an overview of CREB structure, expression, and biological functions in the brain and its interaction with dopamine signaling, neurotrophins, and susceptibility genes for schizophrenia. Animal models in which CREB function is modulated, by either overexpression of the protein or knocked down through gene deletion/mutation, implicating CREB in schizophrenia and antipsychotic drugs efficacy are also discussed. Targeting research and drug development on CREB could potentially accelerate the development of novel medications against schizophrenia.

Maternal immune activation in mid-late gestation alters amphetamine sensitivity and object recognition, but not other schizophrenia-related behaviours in adult rats

Maternal immune activation induced by Poly(I:C) administration is one of the most commonly used animal models of schizophrenia at present. Previous work from our team has demonstrated that some, but not all of the features often reported for maternal immune activation exposure in rodents can be observed in rats exposed to maternal immune activation at mid or late gestation. To determine whether previous findings in our laboratory were due to these time points simply being less sensitive neurodevelopmental periods for rats with regard to maternal immune activation effects, we aimed to investigate whether maternal immune activation at an often-reported sensitive period (mid-late gestation, day 14) resulted in more behavioural features reflective of face validity for schizophrenia. We examined the behavioural outcomes of mid-late maternal immune activation on a battery of behavioural tests aimed at assessing validity for positive, negative and cognitive symptoms of schizophrenia. We found that rats exposed to maternal immune activation, compared to controls, exhibited enhanced sensitivity to the locomotor-stimulating effects of amphetamine and reduced exploration of novel objects. These findings present a unique profile of effects, different to what has already been established for the same time point in rats, and different to what we had found at earlier and later time points. This work, among others in the literature, highlights the varying nature of models of maternal immune activation and we submit that it is essential for laboratories to characterise their models of maternal immune activation on behaviour rather than assuming that the effects from one laboratory apply in their own.

Cannabidiol Administered During Peri-Adolescence Prevents Behavioral Abnormalities in an Animal Model of Schizophrenia.

Schizophrenia is considered a debilitating neurodevelopmental psychiatric disorder and its pharmacotherapy remains problematic without recent major advances. The development of interventions able to prevent the emergence of schizophrenia would therefore represent an enormous progress. Here, we investigated whether treatment with cannabidiol (CBD – a compound of Cannabis sativa that presents an antipsychotic profile in animals and humans) during peri-adolescence would prevent schizophrenia-like behavioral abnormalities in an animal model of schizophrenia: the spontaneously hypertensive rat (SHR) strain. Wistar rats and SHRs were treated with vehicle or CBD from 30 to 60 post-natal days. In experiment 1, schizophrenia-like behaviors (locomotor activity, social interaction, prepulse inhibition of startle and contextual fear conditioning) were assessed on post-natal day 90. Side effects commonly associated with antipsychotic treatment were also evaluated: body weight gain and catalepsy throughout the treatment, and oral dyskinesia 48 h after treatment interruption and on post-natal day 90. In experiment 2, serum levels of triglycerides and glycemia were assessed on post-natal day 61. In experiment 3, levels of BDNF, monoamines, and their metabolites were evaluated on post-natal days 61 and 90 in the prefrontal cortex and striatum. Treatment with CBD prevented the emergence of SHRs’ hyperlocomotor activity (a model for the positive symptoms of schizophrenia) and deficits in prepulse inhibition of startle and contextual fear conditioning (cognitive impairments). CBD did not induce any of the potential motor or metabolic side effects evaluated. Treatment with CBD increased the prefrontal cortex 5-HIAA/serotonin ratio and the levels of 5-HIAA on post-natal days 61 and 90, respectively. Our data provide pre-clinical evidence for a safe and beneficial effect of peripubertal and treatment with CBD on preventing positive and cognitive symptoms of schizophrenia, and suggest the involvement of the serotoninergic system on this effect.

Adenosine Promotes the Recovery of Mice from the Cuprizone-Induced Behavioral and Morphological Changes while Effecting on Microglia and Inflammatory Cytokines in the Brain.

Recent studies have shown that multiple sclerosis (MS) and schizophrenia share similarities in some respects, including white matter damage and neuroinflammation. On the other hand, adenosine was reported to promote oligodendrocyte precursor maturation and remyelinating while influencing microglia activation. The aim of the present study was to examine possible beneficial effects of adenosine on the recovery of cuprizone (CPZ)-exposed mouse which has been used as an animal model of MS and schizophrenia as the CPZ-exposed mouse presents demyelination, oligodendrocyte loss, microglia accumulation, as well as behavioral changes. As reported previously, C57BL/6 mice, after fed CPZ for 5weeks, showed salient demyelination and oligodendrocyte loss in the cerebral cortex (CTX) and hippocampus, in addition to displaying anxiety-like behavior, spatial working memory deficit, and social interaction impairment. Administration of adenosine for 7days during the recovery period after CPZ withdrawal promoted the behavioral recovery of CPZ-exposed mice and accelerated the remyelinating process in the brains of mice after CPZ withdrawal in a dose-dependent manner. In addition, the effective dose (10mg/kg) of adenosine inhibited microglia activation and suppressed abnormal elevation of the pro-inflammatory cytokines IL-1β and TNF-α in CTX and hippocampus, but increased levels of the anti-inflammatory cytokines IL-4 or IL-10 in the same brain regions during the remyelinating process. These results provided an evidence-based rationale for the application of adenosine or its analogues as add-on therapy for schizophrenia.

Albizia zygia root extract exhibits antipsychotic-like properties in murine models of schizophrenia

BackgroundThe root extract of Albizia zygia (DC.) J.F. Macbr. (Leguminosae) is used to manage mental disorders in African traditional medicine. However, its value, particularly, against negative and cognitive symptoms of schizophrenia have not been evaluated. AimThe aim of this study was to evaluate the antipsychotic properties of the hydroethanolic root extract of Albizia zygia (AZE) against positive, negative and cognitive symptoms of schizophrenia in animal models. Materials and methodsThe effects of AZE (30–300 mg kg−1) were evaluated against apomorphine-induced cage climbing as well as ketamine -induced hyperlocomotion, -enhanced immobility, -impaired social interaction and novel object recognition. The propensity of AZE to induce catalepsy and to attenuate haloperidol-induced catalepsy were also investigated. ResultsAZE 30–300 mg kg−1 significantly reduced apomorphine-induced climbing behaviour as well as ketamine-induced hyperlocomotion, immobility and object recognition deficits (at least P < 0.05). Moreover, the extract showed no cataleptic effect but significantly inhibited haloperidol-induced catalepsy at a dose of 30 mg kg−1 (P < 0.05). ConclusionThe root extract of Albizia zygia exhibited an antipsychotic-like activity in mice with potential to alleviate positive, negative and cognitive symptoms of schizophrenia.

Corrigendum: Chronic MK-801 Application in Adolescence and Early Adulthood: A Spatial Working Memory Deficit in Adult Long-Evans Rats But No Changes in the Hippocampal NMDA Receptor Subunits

[This corrects the article on p. 42 in vol. 9, PMID: 29487522.].

Dopamine D2 Receptor Supersensitivity as a Spectrum of Neurotoxicity and Status in Psychiatric Disorders.

Abnormality of dopamine D2 receptor (D2R) function, often observed as D2R supersensitivity (D2RSS), is a commonality of schizophrenia and related psychiatric disorders in humans. Moreover, virtually all psychotherapeutic agents for schizophrenia target D2R in brain. Permanent D2RSS as a feature of a new animal model of schizophrenia was first reported in 1991, and then behaviorally and biochemically characterized over the next 15-20 years. In this model of schizophrenia characterized by production of D2RSS in ontogeny, there are demonstrated alterations of signaling processes, as well as functional links between the biologic template of the animal model and ability of pharmacotherapeutics to modulate or reverse biologic and behavioral modalities toward normality. Another such animal model, featuring knockout of trace amine-associated receptor 1 (TAAR1), demonstrates D2RSS with an increase in the proportion of D2R in the high-affinity state. Currently, TAAR1 agonists are being explored as a therapeutic option for schizophrenia. There is likewise an overlay of D2RSS with substance use disorder. The aspect of adenosine A2A-D2 heteroreceptor complexes in substance use disorder is highlighted, and the association of adenosine A2A receptor antagonists in discriminative and rewarding effects of psychostimulants is outlined. In summary, these new animal models of schizophrenia have face, construct, and predictive validity, and distinct advantages over earlier models. While the review summarizes elements of D2RSS in schizophrenia per se, and its interplay with substance use disorder, a major focus is on presumed new molecular targets attending D2RSS in schizophrenia and related clinical entities.

Changes in behavioural parameters, oxidative stress and neurotrophins in the brain of adult offspring induced to an animal model of schizophrenia: The effects of FA deficient or FA supplemented diet during the neurodevelopmental phase

A deficiency of maternal folic acid (FA) can compromise the function and development of the brain, and may produce a susceptibility to diseases such as schizophrenia (SZ) in the later life of offspring. The aim of this study was to evaluate the effects of both FA deficient and FA supplemented diets during gestation and lactation on behavioural parameters, the markers of oxidative stress and neurotrophic factors in adult offspring which had been subjected to an animal model of SZ. Female mother rats (Dam's) were separated into experimental maternal groups, which began receiving a special diet (food) consisting of the AIN-93 diet, a control diet, or an FA deficient diet during the periods of pregnancy and lactation. Dam's receiving the control diet were further subdivided into four groups: one group received only control diet, while three groups to receive supplementation with FA at different doses (5, 10 and 50 mg/kg). Adult offspring bred from the Dam's were divided into ten groups for induction of the animal model of SZ through the administration of ketamine (Ket) (25 mg/kg). After the last administration of the drug, the animals were subjected to the behavioural tests and were then euthanized. The frontal cortex (FC) and hippocampus (Hip) were then dissected for later biochemical analysis. Our data demonstrates that Ket induced the model of SZ by altering the behavioural parameters (e.g. hyperlocomotion, social impairment, deficits in the sensory-motor profile and memory damage in the adult animals); and also caused changes in the parameters of oxidative stress (lipid hydroperoxide – LPO; 8-isoprostane – 8-ISO; 4-hydroxynonenal – 4-HNE; protein carbonyl content; superoxide dismutase – SOD and catalase – CAT) as well as in the levels of neurotrophic factors (brain-derived neurotrophic factor – BDNF and nerve growth factor – NGF) particularly within the FC of adult offspring. A deficiency in maternal FA, alone or in combination with ket, was able to induce hyperlocomotion and social impairment in the offspring with increased levels of lipid and protein damage (LPO, 8-ISO, 4-HNE, carbonylation of protein) within the FC, increased activity of antioxidant enzymes (SOD and CAT) in both of the brain structures studied, and also reduced the levels of neurotrophins (BDNF and NGF), particularly within the Hip of the adult offspring. Supplementation of FA (5, 10 and 50 mg/kg) to the Dam's was mostly able to prevent the cognitive damage which was induced by Ket in the adult animals. FA (10 and 50 mg/kg) attenuated the action of Ket in the animals in relation to the biochemical parameters, proving the possible neuroprotective effect of FA in the adulthood of offspring that were subjected to the animal model of SZ. Our study indicates that the intake of maternal FA during pregnancy and lactation plays an important role, particularly in the regulation of markers of oxidative stress and neurotrophins.

Impaired pupillary control in "schizophrenia-like" WISKET rats.

Patients with schizophrenia show impairments in autonomic regulation, including pupillomotor control. The aim of this study was to explore the changes of pupillary light reflex in a new substrain (WISKET) with several schizophrenia-like alterations. Male WISKET rats housed individually (for four weeks) and treated with ketamine (for 3 × 5 days) after weaning and naive group-housed Wistar rats (controls) were involved in the study. The pupillary light reflex was studied in two series after sedation (diazepam) or anesthesia (chloral hydrate). Video recordings were evaluated with custom made video analyzer software. Several significant changes were observed between the two groups: the initial and minimum pupil diameters were greater, the degree of the constriction was lower, and the flatness of the curve and the total duration of constriction were shorter in the sedated WISKET rats. No other pupillary parameters (latency, amplitude and redilation) showed significant alterations. Chloral hydrate anesthesia prolonged the constriction and redilation processes compared to the sedated animals, and diminished the differences between the groups. In conclusion, WISKET rats showed disturbances in the pupillary light reflex, suggesting a general shift of autonomic balance towards a sympathetic predominance. The results provide further evidence to support the validity of WISKET rats as a complex, chronic animal model of schizophrenia.

MORRIS WATER MAZE – A BENCH MARK TEST FOR LEARNING AND MEMORY DISORDERS IN ANIMAL MODELS: A REVIEW

The morris water maze (MWM) was developed by morris as a device to investigate spatial learning and memory in laboratory rats. MWM has become one of the most frequently used laboratory tools in behavioral neuroscience. The MWM task has been often used in the validation of rodent models for neurocognitive disorders (e.g., Parkinson, Alzheimer, Epilepsy, and Schizophrenia), and the evaluation of possible neurocognitive treatments. It is also being used to assess the properties of established potential antipsychotics in animal models of Schizophrenia. The MWM task requires rats to find a hidden platform in a large, circular pool of water that is colored opaque with powdered non-fat milk (or) non-toxic tempera paint where they must swim to the hidden platform. Because they are in the opaque water, the animals cannot see the platform and cannot rely on scent to find the escape route. Instead, they must rely on extra-maze cues. The behavior of rat can be evaluated by analyzing the different parameters such as escape latency, swim speed, and path length, and probe trail. The purpose of this review is to briefly describe procedural aspects, interpretational difficulties of data and advantages of MWM. This paradigm has become a benchmark test for learning and memory difficulties in animal models and preclinical research in general.

70. Toward Understanding a Mouse Model of Schizophrenia: From Cellular and Behavioral Phenotypes to a Biomarker of Pathophysiology

Animal models of schizophrenia that present not only pathophysiology but also a wide array of symptoms affected in the patients are in an urgent need. Mounting evidence from human genetics studies indicate an involvement of gene networks related to NMDA receptor/CaMKIIa signaling. Recently, we generated a mouse line constitutively lacking CaMKIIa gene and reported a cellular feature, immature dentate gyrus (iDG), characterized by increased number of immature neuronal progenitors and a concomitant decrease in mature neurons in hippocampus. More importantly, iDG was detected in postmortem brains of a subset of schizophrenia and bipolar, raising a possibility that this cellular phenotype may present underlying pathophysiology of schizophrenia.

The 5α-reductase inhibitor finasteride increases suicide-related aggressive behaviors and blocks clozapine-induced beneficial effects in an animal model of schizophrenia

Death by suicide is 5 times higher among schizophrenia patients than in the general population. There is now compelling evidence suggesting that the pathophysiology of suicide in schizophrenia does not involve central serotonergic neurotransmission disturbances, as has been shown in other contexts. We recently developed and characterized a murine Two-Hit Model of Suicide-related behavior in a schizophrenia-like context (THMS) (gestational inflammation with polyI:C at gestational day 12 followed by post-weaning social isolation). In this THMS model, we have recently shown that the atypical antipsychotic clozapine normalized the prepulse inhibition (PPI) deficits as well suicide-related, impulsive aggressive and anxiety-like behaviors. While the mechanisms underlying the suicide-reducing benefits of clozapine in schizophrenic patients are not well understood, previous works have revealed that clozapine alters brain levels of neurosteroids, such as allopregnanolone. In the present study, we thus investigated the role of endogenous neurosteroids in clozapine action by evaluating whether the 5α-reductase inhibitor finasteride could overturn the ability of clozapine to reduce suicide-related behaviors. We found that clozapine significantly improved the PPI deficits in THMS mice, which could not be reversed by finasteride treatment. However, finasteride counteracted the ability of clozapine to decrease the exploratory behaviors in the open-field test. In the resident-intruder test, THMS mice showed exacerbated aggressiveness and impulsivity following finasteride alone. In this resident-intruder paradigm, clozapine alone effectively blocked the finasteride-enhanced effects on aggression and impulsivity. Altogether, these findings support the existence of a complex interaction between clozapine and neurosteroids in THMS mice. Further investigations are now required to clarify the details of the molecular mechanisms involved.

Olfactory deficit as a result of clozapine withdrawal syndrome in an animal model of schizophrenia: preliminary results.

Clozapine is an antipsychotic that produces serious withdrawal effects in schizophrenic patients. Olfactory deficits are well known as part of negative symptoms, but it is not known whether antipsychotic use and/or withdrawal are implicated. Then, we tested clozapine withdrawal in association with two widely used schizophrenia models: Neonatal immune challenge by Polycitidilic-polyinosinic acid (polyI:C) and ketamine. PolyI:C (or saline) was injected subcutaneously in neonatal period, dose of 5 mg/kg from 2 to 6 Post Natal Days, and ketamine or saline at the dose 25mg/kg intraperitoneally (i.p.), daily for 7 days from 53 to 60 post natal day. Clozapine 10mg/kg (or saline) was administered i.p. from 46 to 60 post natal day. Olfactory discrimination test (sensorial and cognitive deficit) was performed at 61 post natal day, 24h after the last injections. The association of PolyI:C, ketamine and clozapine disrupted Olfactory Discrimination, equating time in familiar and non-familiar compartments. PolyI:C plus ketamine increased crossings between compartments. It was produced, for the first time, an olfactory deficit induced by clozapine withdrawal in Wistar rats subjected to schizophrenia animal models.

27.1 TRANSLATIONAL EVIDENCE OF DOPAMINE-RELATED ALTERATIONS OF BASAL GANGLIA AND THALAMO-CORTICAL NEUROCIRCUITRY IN SCHIZOPHRENIA: A FULL CLINIC-TO-BENCH-TO-CLINIC BACK-TRANSLATION

BackgroundRecent work with a dopamine 2 receptor (D2R) over-expressing (D2R-OE) mouse has suggested that this receptor over-expression leads to a highly plastic increase in bridging collaterals from the associative striatum (AST) to the external segment of the globus pallidus (GPe). Because of the densely interconnected nature of basal ganglia-thalamo-cortical signaling circuitry, we hypothesized and demonstrated in a recent publication that the resting state functional connectivity (RSFC) of AST to multiple cortical and thalamic subregions is broadly disrupted in unmedicated patients with schizophrenia. In this talk, I will present novel simultaneous multi-slice (aka “multiband”) fMRI data that provides the spatial resolution necessary to image smaller basal ganglia substructures (such as the GPe/GPi), and show that unmedicated patients with schizophrenia exhibit specifically disrupted AST-GPe connectivity, as predicted directly from the D2R-OE mouse model findings.In addition, recent work with a 22q11 deletion mouse, which models a similar syndrome in humans that is strongly associated with schizophrenia, has shown that these mice exhibit a D2R-mediated reduction in the strength of excitatory post-synaptic potentials in primary auditory cortex in response to stimulation of the medial geniculate nucleus (MGN) of the thalamus. Consistent with this finding, I will present multiband fMRI data that employs both RSFC and an audio-visual localizer task to demonstrate a specific reduction in RSFC between the MGN and primary auditory cortex, consistent with these findings in the 22q11 mouse.MethodsPartially-overlapping samples of 19 and 14 unmedicated patients with schizophrenia and 15 and 16 matched healthy participants participated in two sets of studies. For both studies, multiband fMRI images were acquired on a GE MR 750 system at the New York State Psychiatric Institute, with a multiband acceleration factor of 6, 2 mm isotropic voxel resolution, and 850 ms TR. Thirty minutes of RSFC data was collected in each participant, and participants in the auditory study also completed a 15 minute audio-visual localizer task that employed sparse temporal sampling with either auditory (9 seconds of a randomized and rapidly-varying musical stimulus) or visual (7.5 Hz alternating checkerboard) stimulation between each acquisition cluster. Basal ganglia subregions were identified via manual drawings conducted by an experienced rater, and the MGN and LGN were identified using the audio-visual localizer task.ResultsUnmedicated patients with schizophrenia showed a significant reduction in RSFC strength between the dorsal caudate and GPe (Cohen’s d = 0.87, P = 0.017), but no other striatal or pallidal subregion pairs, consistent with a specific alteration in anatomical projections between these two regions. In addition, patients with schizophrenia showed a reduction in RSFC between the MGN and primary auditory cortex, as well as between the LGN and primary visual cortex (P < 0.05, alphasim corrected for whole-brain analysis).DiscussionThese findings provide initial support for the existence of D2R-mediated alterations in functional neuroanatomy, first observed in animal models of schizophrenia, in a clinical sample of unmedicated patients. In addition to providing early evidence for potential mechanisms of psychotic phenomena, this work suggests that the use of non-invasive multiband RSFC is a promising approach to translating basic neuroscience findings in animal models back into a clinical setting. Altered circuitry was shown in the D2OE mice to underlie motivational deficits, and we propose that they may have a similar functional impact in patients.

T197. A DRD2 CO-EXPRESSION GENE SET ENRICHED FOR SCHIZOPHRENIA RISK GENES IS CHARACTERIZED BY A COMMON TRANSCRIPTIONAL REGULATION INVOLVING NURR1 TRANSCRIPTION FACTOR

BackgroundGenome-wide association studies demonstrated that multiple genetic variants are associated with schizophrenia (SCZ). Additional evidence revealed that genes are prone to operate in functional molecular networks that subtend complex clinical phenotypes. This knowledge raises the need to investigate how genes linked to SCZ and their possible co-regulators are inserted into molecular networks with a key impact in disease pathogenesis. Using post-mortem brain mRNA data sets (Pergola et al. 2017), we have previously identified a co-expression network enriched for SCZ risk genes, including DRD2, the gene coding for the D2 dopamine receptor, and predicted cognitive and neuroimaging phenotypes of SCZ, as well as response to antipsychotic treatment. Given the relevance of DRD2 to the pathophysiology of SCZ, in the current study we sought to further our understanding of biological mechanisms underpinning co-expression of the DRD2 network. In detail, we aimed at probing the hypothesis that expression of genes within the DRD2-related co-expression network is modulated by a common transcriptional regulation involving one or more Transcription factors (TFs).MethodsIn order to identify TF binding sites (TFBSs) in the promoter region of the 85 genes belonging to the DRD2 co-expression network, we performed a motif enrichment analysis using Pscan and Genomatix MatInspector tools. Biological validation experiments were performed in primary mouse cortical neurons. By real-time PCR analysis we measured the mRNA transcript levels of a group of genes included in the DRD2 co-expression module in basal conditions and upon viral vector-mediated overexpression (OE) and knockdown (KD) of the predicted TFs. We studied expression of genes linked to either DRD2 in the co-expression gene set, such as Gpld1, Chit1, Btg4 and Osr1, or SCZ risk, such as Gatad2a and Slc28a1. We also analyzed transcript levels of Cnr1, which mediates cannabinoid-induced transmission and is relevant to SCZ. Moreover, we analyzed the transcript levels of D2 long splicing isoform (D2L), which was included in the co-expression network, and D2 short splicing isoform (D2S), to verify whether TF regulation was specific for D2L.ResultsPromoters of the DRD2 co-expression gene set were enriched for two TFBSs, recognized by Nur-Related Factor 1 (NURR1, FDR-adjusted p=0.03) and Estrogen-Related Receptor Alpha (ERR1, FDR-adjusted p=0.02), respectively. Validation experiments in mouse primary cortical neurons established that NURR1, and not ERR1, is a regulator of genes of the DRD2 co-expression module analyzed in this study. In detail, Nurr1 gain of function (OE) decreased Cnr1 transcript levels (p=0.0002), whereas it increased Gpld1 transcript levels (p=0.03). The transcript levels of these genes showed an opposite expression trend upon Nurr1 KD. D2L (p=0.008), but not D2S, Gatad2a (p=0.00001), Slc28a1 (p=0.0005) and Chit1 (p=0.02) showed significant expression profile changes only upon Nurr1 OE and vice versa.DiscussionNURR1 participates in developmental, differentiation and survival processes of dopaminergic neurons. It is implicated in transcriptional modulation of genes involved in dopaminergic transmission, including DRD2, as well as in behavioral phenotypes related to dopaminergic anomalies and reminiscent of SCZ in animal models. Finally, NURR1 genetic variation has been associated with SCZ. Taken together, our results are consistent with previous literature and with the hypothesis that molecular mechanisms responsible for co-expression in DRD2 network involve transcriptional regulation by NURR1. They also suggest reliability of our DRD2 co-expression network, and add new insights on mechanisms linked to DRD2-related molecular ensembles and to SCZ.

T48. ANTIPSYCHOTIC EFFICACY OF EVENAMIDE (NW-3509) IS DUE TO MODULATION OF GLUTAMATERGIC DYSREGULATION

BackgroundOver 70% of schizophrenic patients discontinue treatment with first (F)- or second-generation antipsychotics (SGA) due to dissatisfaction with their therapeutic effects; median time to discontinuation ranges from 3–7 months (1). Switching to another antipsychotic, except clozapine, did not yield better results (2). These results indicate it is essential to modulate mechanisms other than dopaminergic (DA)/serotoninergic (5-HT) systems to improve symptoms of schizophrenia (SCZ). Increasingly, NMDA receptor (NMDAr) hypofunction (3) and hippocampal hyperactivity (4) are implicated in the dysregulation of mesolimbic DA and glutamate (Glu) neurons, leading to increasing synaptic activity of Glu in the PFC (5). Augmenting the effects of current antipsychotics with Glu release inhibitors may improve symptoms of psychosis in patients with SCZ.Evenamide does not interact with monoaminergic (DA, 5-HT, NA, H) pathways affected by current antipsychotics, or with >130 different targets involved in CNS activity, except for sodium channels, leading to modulation of Glu release. Evenamide shows efficacy in animal models of SCZ as monotherapy and as an add-on to FGA or SGA, irrespective of whether impairment was spontaneous, or induced by amphetamine, NMDAr antagonists or stress.MethodsIn a pilot, proof of mechanism, randomized, double-blind, placebo-controlled, parallel group, 4-week trial, evenamide (n=50; 15–25 mg bid) or placebo (n=39) was added to patients with SCZ worsening on their current antipsychotic doses of risperidone (RIS; ≥2 mg/day) or aripiprazole (ARI; ≥10 mg/day), in 2 sites in the US (n=61) and 3 in India (n=28).Results89 patients with SCZ (mean baseline PANSS total: 62.9 ± 7.4; CGI-S: 3.5 ± 0.5), experiencing break-through psychotic symptoms on previously effective and stable doses of RIS (mean dose: 4.2 ± 2.0 mg/day; n=70) or ARI (mean dose: 19.7 ± 7.0 mg/day; n=19) were randomized (1.3:1 ratio) to treatment with evenamide or placebo. Analyses demonstrated the addition of evenamide to RIS or ARI was associated with statistically significant efficacy, based on the PANSS Positive Symptoms sub-scale (mean change, responders), and CGI-C responder rates. The study treatments were very well tolerated; 2 patients on evenamide discontinued treatment due to AEs (atrial fibrillation and seizure). The most common AEs (evenamide vs placebo [%]), were somnolence (16 vs 12.8%), insomnia (10 vs 6%) and headache (6 vs 0%).DiscussionAddition of evenamide in patients worsening on SGAs modulating DA/5-HT significantly improved positive symptoms and CGI. No AEs such as EPS, endocrine, or sexual side effects, or weight gain were noted. These data indicate that evenamide’s Glu antagonism, demonstrated in preclinical experiments, is of value in patients worsening on current antipsychotics. Evenamide, as monotherapy or add-on, has reversed ketamine- and PCP-induced worsening of PPI. The results in the pilot clinical trial demonstrated an absence of side effects common with DA/5-HT blockers, and a rapid onset of action mediated by evenamide targeting altered Glu transmission in patients in whom SGA treatment had lost its efficacy.Efficacy of evenamide as add-on to antipsychotics would revolutionize development of novel antipsychotics targeting aberrant firing and Glu transmission in SCZ. Potentially pivotal studies with evenamide are in planning to demonstrate that the addition of evenamide, a Glu release inhibitor, augments antipsychotic efficacy in patients worsening on current antipsychotics, and in patients with treatment-resistant SCZ not responding/worsening on clozapine.