Paliperidone Reversion of Maternal Immune Activation-Induced Changes on Brain Serotonin and Kynurenine Pathways

Emerging evidence indicates that early-life exposure to environmental factors may increase the risk for schizophrenia via inflammatory mechanisms. Inflammation can alter the metabolism of tryptophan through the oxidative kynurenine pathway to compounds with neurotoxic and neuroprotective activity and compromise serotonin (5-HT) synthesis. Here we investigate the role of serotonergic and kynurenine pathways in the maternal immune activation (MIA) animal model of schizophrenia. The potential reversion exerted by long-term antipsychotic treatment was also evaluated. MIA was induced by prenatal administration of polyinosinic:polycytidylic acid (poly (I:C)) in mice. Expression of different proteins and the content of different metabolites involved in the function of serotonergic and kynurenine pathways was assessed by RT-PCR, immunoblot and ELISA analyses in frontal cortex of the offspring after puberty. MIA decreased tissue 5-HT content and promoted changes in the expression of serotonin transporter, 5-HT2A and 5-HT2C receptors. Expression of indoleamine 2,3-dioxygenase 2 (IDO2) and kynurenine 3-monooxygenase (KMO) was increased by poly (I:C) whereas kynurenine aminotransferase II and its metabolite kynurenic acid were not altered. Long-term paliperidone was able to counteract MIA-induced changes in 5-HT and KMO, and to increase tryptophan availability and tryptophan hydroxylase-2 expression in poly (I:C) mice but not in controls. MIA-induced increase of the cytotoxic risk ratio of kynurenine metabolites (quinolinic/kynurenic acid) was also reversed by paliperidone. MIA induces specific long-term brain effects on serotonergic activity. Such effects seem to be related with alternative activation of the kynurenine metabolic pathway towards a cytotoxic status. Atypical antipsychotic paliperodine partially remediates abnormalities observed after MIA.This work was supported by MINECO-FEDER Funds (SAF201675500-R to JL; SAF2017-88126-R to JM); Centro de Investigacion en Red de Salud Mental, CIBERSAM; and the Basque Government (IT1211-19). Editoria

Behavioural Evaluation of a Translational Animal Model of Schizophrenia

Presented at 1st Meeting in Translational Pharmacology 38th SEF national meeting/9th SEFF meeting 19–20 June 2018, SpainSchizophrenia (SZ) is a chronic and disabling psychiatric disorder affecting about 1% of the population worldwide. Schizophrenia comprises positive and negative symptoms as well as cognitive deficits. Epidemiological and experimental studies indicate that infections during the gestational period represent a risk factor to develop SZ along lifetime, which in combination with stressful events in adolescence may lead to the SZ onset. The aim of the present study was to create a translational “double-hit” animal model of SZ in male and female mice, based in maternal immune activation (MIA, hit-1)—injection of poly(I:C) to pregnant dams, 7.5 mg/kg i.p.—and social isolation (SI, hit-2) in the peri-pubertal period (3–11 weeks). In the four experimental groups (hit-1, hit-2, double-hit and control) locomotion and anxiety were assessed using the Open Field Test (OFT), and the cognitive status (declarative/episodic memory) was evaluated by means of the Novel Object Recognition Test (NORT). No differences were observed in the spontaneous locomotor activity between any of the groups, neither in females nor in males. However, an increase in the percentage of time spent in the centre of the OFT was significantly associated to the hit-1 (MIA) only in female mice (F[1,53] = 4.252; P = 0.044, n = 57). Moreover, a significant decrease in the discrimination index in the NORT was also associated to the hit-1 (MIA) in the subgroup of female mice (F[1,55] = 7.266; P = 0.0093, n = 59). These preliminary results indicate that MIA produces a greater impact in female mice inducing an anxiolytic-like phenotype and cognitive impairments.Basque Government (IT616/13) MSCA-2016-IF 747487 to C.Muguruza

Characterization of dopamine D2 receptor coupling to G proteins in postmortem brain of subjects with schizophrenia

Background: Alterations of dopamine D-1 (D1R) and D-2 receptor (D2R) are proposed in schizophrenia but brain neuroimaging and postmortem studies have shown controversial results in relation to D1R and D2R density. Besides, scarce information on the functionality of brain D1R and D2R is available. The present study characterized G-protein activation by D1R and D2R agonists in postmortem human brain. Furthermore, D2R functional status was compared between schizophrenia and control subjects. Methods: G-protein receptor coupling was assessed in control caudate nucleus and frontal cortex by [S-35]GTP gamma S-binding stimulation induced by increasing concentrations (10(-10)-10(-3) M) of dopamine, and the selective dopaminergic agonists SKF38393 (D1R) and NPA (D2R). Concentration-response curves to NPA stimulation of [S-35]GTP gamma S binding were analyzed in antipsychotic-free (n = 10) and antipsychotic-treated (n = 7) schizophrenia subjects and matched controls (n = 17). Results: In caudate, [S-35]GTP gamma S-binding responses to agonists were compatible with the existence of functional D2R. In contrast, stimulations in cortex showed responses that did not correspond to D1R or D2R. [S-35]GTP gamma S-binding activation by NPA in caudate displayed biphasic curves with similar profile in schizophrenia (EC50H = 7.94 nM; EC50L = 7.08 mu M) and control (EC50H = 7.24 nM; EC50L = 15.14 mu M) subjects. The presence or absence of antipsychotic medication did not influence the pharmacological parameters. Conclusions: Feasibility of functional evaluation of dopamine receptors in postmortem human brain by conventional [S-35]GTP gamma S-binding assays appears to be restricted to signalling through inhibitory G(i/o) proteins. These findings provide functional information about brain D2R status in subjects with schizophrenia and do not support the existence of D2R supersensitive in this mental disorder.This work was supported by the Spanish State Research Agency and EDR Funds (SAF-2017-88126-R to JJM;PID2019-106404RB-100 to LFC), the Basque Government (IT1211/19 to JJM ; ELKARTEK Programme KK-2019/00049 to RD-A), and the National Institutes of Health (R01MH084894 & NIH-R01MH111940 to JG-M)

Inhibition of Prolyl Oligopeptidase Restores Prohibitin 2 Levels in Psychosis Models: Relationship to Cognitive Deficits in Schizophrenia

Cognitive impairment represents one of the core features of schizophrenia. Prolyl Oligopeptidase (POP) inhibition is an emerging strategy for compensating cognitive deficits in hypoglutamatergic states such as schizophrenia, although little is known about how POP inhibitors exert their pharmacological activity. The mitochondrial and nuclear protein Prohibitin 2 (PHB2) could be dysregulated in schizophrenia. However, altered PHB2 levels in schizophrenia linked to N-methyl-D-aspartate receptor (NMDAR) activity and cognitive deficits are still unknown. To shed light on this, we measured the PHB2 levels by immunoblot in a postmortem dorsolateral prefrontal cortex (DLPFC) of schizophrenia subjects, in the frontal pole of mice treated with the NMDAR antagonists phencyclidine and dizocilpine, and in rat cortical astrocytes and neurons treated with dizocilpine. Mice and cells were treated in combination with the POP inhibitor IPR19. The PHB2 levels were also analyzed by immunocytochemistry in rat neurons. The PHB2 levels increased in DLPFC in cases of chronic schizophrenia and were associated with cognitive impairments. NMDAR antagonists increased PHB2 levels in the frontal pole of mice and in rat astrocytes and neurons. High levels of PHB2 were found in the nucleus and cytoplasm of neurons upon NMDAR inhibition. IPR19 restored PHB2 levels in the acute NMDAR inhibition. These results show that IPR19 restores the upregulation of PHB2 in an acute NMDAR hypoactivity stage suggesting that the modulation of PHB2 could compensate NMDAR-dependent cognitive impairments in schizophrenia.This research was funded by a Miguel Servet grant, MS16/00153-CP16/00153 to BR, financed and integrated into the National R+D+I and funded by the Instituto de Salud Carlos III (ISCIII, Spanish Ministry of Health)—General Branch Evaluation and Promotion of Health Research—and the European Regional Development Fund (ERDF). This work was also supported by ISCIII PI18/00213 to BR, the Predoctoral Fellowship Program from the ISCIII (PFIS) FI19/00080 to E.V, FPU fellowship from the Spanish Ministry of Education, Culture, and Sports FPU17/06000 to E.E., the CONICYT-Doctorado Becas Chile 2015, 72160426 to AV, and the CIBERSAM (Spanish Ministry of Economy, Industry, and Competitiveness, Institute of Health Carlos III). CIBERSAM will be encharged to fund open access publication fees

Caracterización de las proteínas del complejo SNARE en esquizofrenia y su tratamiento

248 p.La esquizofrenia es una enfermedad de base biológica cuyo sustrato es poco conocido. A partir de un estudio de proteómica comparativa realizados en cerebro postmortem de individuos con esquizofrenia y individuos control se ha establecido que la proteína Munc18-1 se sobreexpresa en esquizofrenia.La primera parte de esta Tesis se compone de la evaluación proteica de esa y otras proteínas presinápticas en una población de individuos con esquizofrenia, individuos suicidas no esquizofrénicos, individuos diagnosticados con depresión mayor e individuos control. Dentro de estas poblaciones se pudo hacer una división entre individuos con presencia y ausencia de medicación antipsicótica en plasma en el momento del fallecimiento.Para evaluar la sobreexpresión de Munc18-1a, se ha diseñado un ratón (Munc18-OE) como posible modelo animal de esquizofrenia. En esta Tesis se ha realizado una evaluación neuroquímica y de comportamiento dentro de un proyecto más amplio caracterizando este animal y su respuesta al antipsicótico clozapina

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

Abstract 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

Behavioral, neurochemical and morphological changes induced by the overexpression of munc18-1a in brain of mice: relevance to schizophrenia

Overexpression of the mammalian homolog of the unc-18 gene (munc18-1) has been described in the brain of subjects with schizophrenia. Munc18-1 protein is involved in membrane fusion processes, exocytosis and neurotransmitter release. A transgenic mouse strain that overexpresses the protein isoform munc18-1a in the brain was characterized. This animal displays several schizophrenia-related behaviors, supersensitivity to hallucinogenic drugs and deficits in prepulse inhibition that reverse after antipsychotic treatment. Relevant brain areas (that is, cortex and striatum) exhibit reduced expression of dopamine D-1 receptors and dopamine transporters together with enhanced amphetamine-induced in vivo dopamine release. Magnetic resonance imaging demonstrates decreased gray matter volume in the transgenic animal. In conclusion, the mouse overexpressing brain munc18-1a represents a new valid animal model that resembles functional and structural abnormalities in patients with schizophrenia.Brainco Biopharma SL; Centro de Investigacion Biomedica en Red de Salud Mental; Instituto de Salud Carlos III (CIBERSAM); Spanish MICINN; FEDER SAF2009-08460, SAF2010-21948,AGL2009-11358, SAF2011-29918, PI10/02986, CP08/00017,CEN-20101014; Basque Government PR10UN01 IT-199/07; University of the Basque Country (UPV/EHU); Complutense University of Madrid UCM GR42/10-96207