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Molecular Mechanisms of Schizophrenia and Novel Targets

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Biochemistry".

Deadline for manuscript submissions: closed (30 November 2021) | Viewed by 74734

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Guest Editor
CSIC—Instituto de Parasitologia y Biomedicina Lopez Neyra (IPBLN), Granada, Spain
Interests: schizophrenia; neurotransmitter receptors; cell signaling; genomics; proteomics; molecular pharmacology; antipsychotics.
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The biological basis of schizophrenia, and many other mental diseases, has been the object of investigation for neuroscientists and psychiatrists over the last century. It is now well accepted that any scientific advance leading to the elucidation of the pathophysiology of these mental disorders, in particular schizophrenia and psychosis, will facilitate the comprehension of brain functioning in those aspects of mind and consciousness as well as the development of therapeutic strategies to treat these illnesses. During the last few decades, we have witnessed an extraordinary advance in all aspects of molecular approaches to interrogating mechanisms involved in biological processes, from the subcellular level to a more organized anatomical or physiological order. In this Special Issue, we aim to present a collection of the latest advances in the molecular basis of schizophrenia, covering a multidisciplinary perspective that includes molecular pharmacology, cellular signaling, genomics, and proteomics.

Prof. Juan F. Lopez-Gimenez
Guest Editor

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Keywords

  • schizophrenia
  • neurotransmitter receptors
  • cell signaling
  • genomics
  • proteomics
  • molecular pharmacology
  • antipsychotics
  • cellular models

Published Papers (21 papers)

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17 pages, 1256 KiB  
Article
N-Acetylcysteine and Aripiprazole Improve Social Behavior and Cognition and Modulate Brain BDNF Levels in a Rat Model of Schizophrenia
by Zofia Rogóż, Kinga Kamińska, Marta Anna Lech and Elżbieta Lorenc-Koci
Int. J. Mol. Sci. 2022, 23(4), 2125; https://doi.org/10.3390/ijms23042125 - 15 Feb 2022
Cited by 9 | Viewed by 2538
Abstract
Treatment of negative symptoms and cognitive disorders in patients with schizophrenia is still a serious clinical problem. The aim of our study was to compare the efficacy of chronic administration of the atypical antipsychotic drug aripiprazole (7-{4-[4-(2,3-dichlorophenyl)-1-piperazinyl] butoxy}-3,4-dihydro-2(1H)-quinolinone; ARI) and the well-known antioxidant [...] Read more.
Treatment of negative symptoms and cognitive disorders in patients with schizophrenia is still a serious clinical problem. The aim of our study was to compare the efficacy of chronic administration of the atypical antipsychotic drug aripiprazole (7-{4-[4-(2,3-dichlorophenyl)-1-piperazinyl] butoxy}-3,4-dihydro-2(1H)-quinolinone; ARI) and the well-known antioxidant N-acetylcysteine (NAC) both in alleviating schizophrenia-like social and cognitive deficits and in reducing the decreases in the levels of the brain-derived neurotrophic factor (BDNF) in the prefrontal cortex (PFC) and hippocampus (HIP) of adult Sprague-Dawley rats, that have been induced by chronic administration of the model compound L-buthionine-(S, R)-sulfoximine (BSO) during the early postnatal development (p5–p16). ARI was administered at doses of 0.1 and 0.3 mg/kg while NAC at doses of 10 and 30 mg/kg, alone or in combination. Administration of higher doses of ARI or NAC alone, or co-treatment with lower, ineffective doses of these drugs significantly improved social and cognitive performance as assessed in behavioral tests. Both doses of NAC and 0.3 mg/kg of ARI increased the expression of BDNF mRNA in the PFC, while all doses of these drugs and their combinations enhanced the levels of BDNF protein in this brain structure. In the HIP, only 0,3 mg/kg ARI increased the levels of both BDNF mRNA and its protein. These data show that in the rat BSO-induced neurodevelopmental model of schizophrenia, ARI and NAC differently modulated BDNF levels in the PFC and HIP. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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20 pages, 2493 KiB  
Article
Analysis of mRNA and Protein Levels of CAP2, DLG1 and ADAM10 Genes in Post-Mortem Brain of Schizophrenia, Parkinson’s and Alzheimer’s Disease Patients
by Anna Di Maio, Arianna De Rosa, Silvia Pelucchi, Martina Garofalo, Benedetta Marciano, Tommaso Nuzzo, Fabrizio Gardoni, Andrea M. Isidori, Monica Di Luca, Francesco Errico, Andrea De Bartolomeis, Elena Marcello and Alessandro Usiello
Int. J. Mol. Sci. 2022, 23(3), 1539; https://doi.org/10.3390/ijms23031539 - 28 Jan 2022
Cited by 9 | Viewed by 2915
Abstract
Schizophrenia (SCZ) is a mental illness characterized by aberrant synaptic plasticity and connectivity. A large bulk of evidence suggests genetic and functional links between postsynaptic abnormalities and SCZ. Here, we performed quantitative PCR and Western blotting analysis in the dorsolateral prefrontal cortex (DLPFC) [...] Read more.
Schizophrenia (SCZ) is a mental illness characterized by aberrant synaptic plasticity and connectivity. A large bulk of evidence suggests genetic and functional links between postsynaptic abnormalities and SCZ. Here, we performed quantitative PCR and Western blotting analysis in the dorsolateral prefrontal cortex (DLPFC) and hippocampus of SCZ patients to investigate the mRNA and protein expression of three key spine shapers: the actin-binding protein cyclase-associated protein 2 (CAP2), the sheddase a disintegrin and metalloproteinase 10 (ADAM10), and the synapse-associated protein 97 (SAP97). Our analysis of the SCZ post-mortem brain indicated increased DLG1 mRNA in DLPFC and decreased CAP2 mRNA in the hippocampus of SCZ patients, compared to non-psychiatric control subjects, while the ADAM10 transcript was unaffected. Conversely, no differences in CAP2, SAP97, and ADAM10 protein levels were detected between SCZ and control individuals in both brain regions. To assess whether DLG1 and CAP2 transcript alterations were selective for SCZ, we also measured their expression in the superior frontal gyrus of patients affected by neurodegenerative disorders, like Parkinson’s and Alzheimer’s disease. Interestingly, also in Parkinson’s disease patients, we found a selective reduction of CAP2 mRNA levels relative to controls but unaltered protein levels. Taken together, we reported for the first time altered CAP2 expression in the brain of patients with psychiatric and neurological disorders, thus suggesting that aberrant expression of this gene may contribute to synaptic dysfunction in these neuropathologies. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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28 pages, 43395 KiB  
Article
Nitric Oxide-Dependent Mechanisms Underlying MK-801- or Scopolamine-Induced Memory Dysfunction in Animals: Mechanistic Studies
by Paulina Cieślik, Anna Siekierzycka, Adrianna Radulska, Agata Płoska, Grzegorz Burnat, Piotr Brański, Leszek Kalinowski and Joanna M. Wierońska
Int. J. Mol. Sci. 2021, 22(22), 12282; https://doi.org/10.3390/ijms222212282 - 13 Nov 2021
Cited by 8 | Viewed by 2366
Abstract
MK-801, an NMDA receptor antagonist, and scopolamine, a cholinergic receptor blocker, are widely used as tool compounds to induce learning and memory deficits in animal models to study schizophrenia or Alzheimer-type dementia (AD), respectively. Memory impairments are observed after either acute or chronic [...] Read more.
MK-801, an NMDA receptor antagonist, and scopolamine, a cholinergic receptor blocker, are widely used as tool compounds to induce learning and memory deficits in animal models to study schizophrenia or Alzheimer-type dementia (AD), respectively. Memory impairments are observed after either acute or chronic administration of either compound. The present experiments were performed to study the nitric oxide (NO)-related mechanisms underlying memory dysfunction induced by acute or chronic (14 days) administration of MK-801 (0.3 mg/kg, i.p.) or scopolamine (1 mg/kg, i.p.). The levels of L-arginine and its derivatives, L-citrulline, L-glutamate, L-glutamine and L-ornithine, were measured. The expression of constitutive nitric oxide synthases (cNOS), dimethylaminohydrolase (DDAH1) and protein arginine N-methyltransferases (PMRTs) 1 and 5 was evaluated, and the impact of the studied tool compounds on cGMP production and NMDA receptors was measured. The studies were performed in both the cortex and hippocampus of mice. S-nitrosylation of selected proteins, such as GLT-1, APP and tau, was also investigated. Our results indicate that the availability of L-arginine decreased after chronic administration of MK-801 or scopolamine, as both the amino acid itself as well as its level in proportion to its derivatives (SDMA and NMMA) were decreased. Additionally, among all three methylamines, SDMA was the most abundant in the brain (~70%). Administration of either compound impaired eNOS-derived NO production, increasing the monomer levels, and had no significant impact on nNOS. Both compounds elevated DDAH1 expression, and slight decreases in PMRT1 and PMRT5 in the cortex after scopolamine (acute) and MK-801 (chronic) administration were observed in the PFC, respectively. Administration of MK-801 induced a decrease in the cGMP level in the hippocampus, accompanied by decreased NMDA expression, while increased cGMP production and decreased NMDA receptor expression were observed after scopolamine administration. Chronic MK-801 and scopolamine administration affected S-nitrosylation of GLT-1 transport protein. Our results indicate that the analyzed tool compounds used in pharmacological models of schizophrenia or AD induce changes in NO-related pathways in the brain structures involved in cognition. To some extent, the changes resemble those observed in human samples. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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20 pages, 3551 KiB  
Article
Identification of Molecular Markers of Clozapine Action in Ketamine-Induced Cognitive Impairment: A GPCR Signaling PathwayFinder Study
by Agata Korlatowicz, Maciej Kuśmider, Marta Szlachta, Paulina Pabian, Joanna Solich, Marta Dziedzicka-Wasylewska and Agata Faron-Górecka
Int. J. Mol. Sci. 2021, 22(22), 12203; https://doi.org/10.3390/ijms222212203 - 11 Nov 2021
Cited by 3 | Viewed by 1793
Abstract
Background: Cognitive disorders associated with schizophrenia are closely linked to prefrontal cortex (PFC) dysfunction. Administration of the non-competitive NMDA receptor antagonist ketamine (KET) induces cognitive impairment in animals, producing effects similar to those observed in schizophrenic patients. In a previous study, we showed [...] Read more.
Background: Cognitive disorders associated with schizophrenia are closely linked to prefrontal cortex (PFC) dysfunction. Administration of the non-competitive NMDA receptor antagonist ketamine (KET) induces cognitive impairment in animals, producing effects similar to those observed in schizophrenic patients. In a previous study, we showed that KET (20 mg/kg) induces cognitive deficits in mice and that administration of clozapine (CLZ) reverses this effect. To identify biochemical mechanisms related to CLZ actions in the context of KET-induced impairment, we performed a biochemical analysis using the same experimental paradigm—acute and sub-chronic administration of these drugs (0.3 and 1 mg/kg). Methods: Since the effect of CLZ mainly depends on G-protein-related receptors, we used the Signaling PathwayFinder Kit to identify 84 genes involved in GPCR-related signal transduction and then verified the genes that were statistically significantly different on a larger group of mice using RT-PCR and Western blot analyses after the administration of acute and sub-chronic drugs. Results: Of the 84 genes involved in GPCR-related signal transduction, the expression of six, βarrestin1, βarrestin2, galanin receptor 2 (GalR2), dopamine receptor 2 (DRD2), metabotropic glutamate receptor 1 (mGluR1), and metabotropic glutamate receptor 5 (mGluR5), was significantly altered. Since these genes affect the levels of other signaling proteins, e.g., extracellular signal-regulated kinase 1/2 (ERK1/2), G protein-coupled receptor kinase 2 (Grk2), and G protein-gated inwardly rectifying potassium 3 (Girk3), we determined their levels in PFC using Western blot. Most of the observed changes occurred after acute treatment with 0.3 mg/kg CLZ. We showed that acute treatment with CLZ at a lower dose significantly increased βarrestin1 and ERK1/2. KET treatment induced the upregulation of βarrestin1. Joint administration of these drugs had no effect on the βarrestin1 level. Conclusion: The screening kit we used to study the expression of GPCR-related signal transduction allowed us to select several important genes affected by CLZ. However, the obtained data do not explain the mechanism of action of CLZ that is responsible for reversing KET-induced cognitive impairment. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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22 pages, 6191 KiB  
Article
Perineuronal Nets in the Prefrontal Cortex of a Schizophrenia Mouse Model: Assessment of Neuroanatomical, Electrophysiological, and Behavioral Contributions
by Razia Sultana, Charles Brady Brooks, Amita Shrestha, Olalekan Michael Ogundele and Charles Chulsoo Lee
Int. J. Mol. Sci. 2021, 22(20), 11140; https://doi.org/10.3390/ijms222011140 - 15 Oct 2021
Cited by 9 | Viewed by 2807
Abstract
Schizophrenia is a neurodevelopmental disorder whose etiopathogenesis includes changes in cellular as well as extracellular structures. Perineuronal nets (PNNs) associated with parvalbumin-positive interneurons (PVs) in the prefrontal cortex (PFC) are dysregulated in schizophrenia. However, the postnatal development of these structures along with their [...] Read more.
Schizophrenia is a neurodevelopmental disorder whose etiopathogenesis includes changes in cellular as well as extracellular structures. Perineuronal nets (PNNs) associated with parvalbumin-positive interneurons (PVs) in the prefrontal cortex (PFC) are dysregulated in schizophrenia. However, the postnatal development of these structures along with their associated neurons in the PFC is unexplored, as is their effects on behavior and neural activity. Therefore, in this study, we employed a DISC1 (Disruption in Schizophrenia) mutation mouse model of schizophrenia to assess these developmental changes and tested whether enzymatic digestion of PNNs in the PFC affected schizophrenia-like behaviors and neural activity. Developmentally, we found that the normal formation of PNNs, PVs, and colocalization of these two in the PFC, peaked around PND 22 (postnatal day 22). However, in DISC1, mutation animals from PND 0 to PND 60, both PNNs and PVs were significantly reduced. After enzymatic digestion of PNNs with chondroitinase in adult animals, the behavioral pattern of control animals mimicked that of DISC1 mutation animals, exhibiting reduced sociability, novelty and increased ultrasonic vocalizations, while there was very little change in other behaviors, such as working memory (Y-maze task involving medial temporal lobe) or depression-like behavior (tail-suspension test involving processing via the hypothalamic pituitary adrenal (HPA) axis). Moreover, following chondroitinase treatment, electrophysiological recordings from the PFC exhibited a reduced proportion of spontaneous, high-frequency firing neurons, and an increased proportion of irregularly firing neurons, with increased spike count and reduced inter-spike intervals in control animals. These results support the proposition that the aberrant development of PNNs and PVs affects normal neural operations in the PFC and contributes to the emergence of some of the behavioral phenotypes observed in the DISC1 mutation model of schizophrenia. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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22 pages, 14150 KiB  
Article
Analysis of Molecular Networks in the Cerebellum in Chronic Schizophrenia: Modulation by Early Postnatal Life Stressors in Murine Models
by América Vera-Montecinos, Ricard Rodríguez-Mias, Karina S. MacDowell, Borja García-Bueno, Álvaro G. Bris, Javier R. Caso, Judit Villén and Belén Ramos
Int. J. Mol. Sci. 2021, 22(18), 10076; https://doi.org/10.3390/ijms221810076 - 17 Sep 2021
Cited by 6 | Viewed by 2567
Abstract
Despite the growing importance of the cerebellum as a region highly vulnerable to accumulating molecular errors in schizophrenia, limited information is available regarding altered molecular networks with potential therapeutic targets. To identify altered networks, we conducted one-shot liquid chromatography–tandem mass spectrometry in postmortem [...] Read more.
Despite the growing importance of the cerebellum as a region highly vulnerable to accumulating molecular errors in schizophrenia, limited information is available regarding altered molecular networks with potential therapeutic targets. To identify altered networks, we conducted one-shot liquid chromatography–tandem mass spectrometry in postmortem cerebellar cortex in schizophrenia and healthy individuals followed by bioinformatic analysis (PXD024937 identifier in ProteomeXchange repository). A total of 108 up-regulated proteins were enriched in stress-related proteins, half of which were also enriched in axonal cytoskeletal organization and vesicle-mediated transport. A total of 142 down-regulated proteins showed an enrichment in proteins involved in mitochondrial disease, most of which were also enriched in energy-related biological functions. Network analysis identified a mixed module of mainly axonal-related pathways for up-regulated proteins with a high number of interactions for stress-related proteins. Energy metabolism and neutrophil degranulation modules were found for down-regulated proteins. Further, two double-hit postnatal stress murine models based on maternal deprivation combined with social isolation or chronic restraint stress were used to investigate the most robust candidates of generated networks. CLASP1 from the axonal module in the model of maternal deprivation was combined with social isolation, while YWHAZ was not altered in either model. METTL7A from the degranulation pathway was reduced in both models and was identified as altered also in previous gene expression studies, while NDUFB9 from the energy network was reduced only in the model of maternal deprivation combined with social isolation. This work provides altered stress- and mitochondrial disease-related proteins involved in energy, immune and axonal networks in the cerebellum in schizophrenia as possible novel targets for therapeutic interventions and suggests that METTL7A is a possible relevant altered stress-related protein in this context. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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30 pages, 11017 KiB  
Article
Inhibition of BET Proteins during Adolescence Affects Prefrontal Cortical Development: Relevance to Schizophrenia
by Wiktor Bilecki, Agnieszka Wawrzczak-Bargieła, Iwona Majcher-Maślanka, Magdalena Chmelova and Marzena Maćkowiak
Int. J. Mol. Sci. 2021, 22(16), 8710; https://doi.org/10.3390/ijms22168710 - 13 Aug 2021
Cited by 5 | Viewed by 1818
Abstract
Background: The present study investigated the role of proteins from the bromodomain and extra-terminal (BET) family in schizophrenia-like abnormalities in a neurodevelopmental model of schizophrenia induced by prenatal methylazoxymethanol (MAM) administration (MAM-E17). Methods: An inhibitor of BET proteins, JQ1, was administered during adolescence [...] Read more.
Background: The present study investigated the role of proteins from the bromodomain and extra-terminal (BET) family in schizophrenia-like abnormalities in a neurodevelopmental model of schizophrenia induced by prenatal methylazoxymethanol (MAM) administration (MAM-E17). Methods: An inhibitor of BET proteins, JQ1, was administered during adolescence on postnatal days (P) 23–P29, and behavioural responses (sensorimotor gating, recognition memory) and prefrontal cortical (mPFC) function (long-term potentiation (LTP), molecular and proteomic analyses) studies were performed in adult males and females. Results: Deficits in sensorimotor gating and recognition memory were observed only in MAM-treated males. However, adolescent JQ1 treatment affected animals of both sexes in the control but not MAM-treated groups and reduced behavioural responses in both sexes. An electrophysiological study showed LTP impairments only in male MAM-treated animals, and JQ1 did not affect LTP in the mPFC. In contrast, MAM did not affect activity-dependent gene expression, but JQ1 altered gene expression in both sexes. A proteomic study revealed alterations in MAM-treated groups mainly in males, while JQ1 affected both sexes. Conclusions: MAM-induced schizophrenia-like abnormalities were observed only in males, while adolescent JQ1 treatment affected memory recognition and altered the molecular and proteomic landscape in the mPFC of both sexes. Thus, transient adolescent inhibition of the BET family might prompt permanent alterations in the mPFC. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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22 pages, 5073 KiB  
Article
Serotonergic–Muscarinic Interaction within the Prefrontal Cortex as a Novel Target to Reverse Schizophrenia-Related Cognitive Symptoms
by Paulina Cieślik, Adrianna Radulska, Grzegorz Burnat, Leszek Kalinowski and Joanna M. Wierońska
Int. J. Mol. Sci. 2021, 22(16), 8612; https://doi.org/10.3390/ijms22168612 - 10 Aug 2021
Cited by 8 | Viewed by 1878
Abstract
Recent studies revealed that the activation of serotonergic 5-HT1A and muscarinic M1, M4, or M5 receptors prevent MK-801-induced cognitive impairments in animal models. In the present study, the effectiveness of the simultaneous activation of 5-HT1A and [...] Read more.
Recent studies revealed that the activation of serotonergic 5-HT1A and muscarinic M1, M4, or M5 receptors prevent MK-801-induced cognitive impairments in animal models. In the present study, the effectiveness of the simultaneous activation of 5-HT1A and muscarinic receptors at preventing MK-801-induced cognitive deficits in novel object recognition (NOR) or Y-maze tests was investigated. Activators of 5-HT1A (F15599), M1 (VU0357017), M4 (VU0152100), or M5 (VU0238429) receptors administered at top doses for seven days reversed MK-801-induced deficits in the NOR test, similar to the simultaneous administration of subeffective doses of F15599 (0.05 mg/kg) with VU0357017 (0.15 mg/kg), VU0152100 (0.05 mg/kg), or VU0238429 (1 mg/kg). The compounds did not prevent the MK-801-induced impairment when administered acutely. Their activity was less evident in the Y-maze. Pharmacokinetic studies revealed high brain penetration of F15599 (brain/plasma ratio 620%), which was detected in the frontal cortex (FC) up to 2 h after administration. Decreases in the brain penetration properties of the compounds were observed after acute administration of the combinations, which might have influenced behavioral responses. This negative effect on brain penetration was not observed when the compounds were administered repeatedly. Based on our results, prolonged administration of a 5-HT1A activator with muscarinic receptor ligands may be effective at reversing cognitive decline related to schizophrenia, and the FC may play a critical role in this interaction. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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13 pages, 2021 KiB  
Article
The Role of the Second Extracellular Loop of Norepinephrine Transporter, Neurotrophin-3 and Tropomyosin Receptor Kinase C in T Cells: A Peripheral Biomarker in the Etiology of Schizophrenia
by Daniela Rodrigues-Amorim, Marta Iglesias-Martínez-Almeida, Tania Rivera-Baltanás, Patricia Fernández-Palleiro, Luis Freiría-Martínez, Cynthia Rodríguez-Jamardo, María Comís-Tuche, María del Carmen Vallejo-Curto, María Álvarez-Ariza, Marta López-García, Elena de las Heras, Alejandro García-Caballero, Jose Manuel Olivares and Carlos Spuch
Int. J. Mol. Sci. 2021, 22(16), 8499; https://doi.org/10.3390/ijms22168499 - 07 Aug 2021
Cited by 3 | Viewed by 3204
Abstract
The neurobiology of schizophrenia is multifactorial, comprising the dysregulation of several biochemical pathways and molecules. This research proposes a peripheral biomarker for schizophrenia that involves the second extracellular loop of norepinephrine transporter (NEText), the tropomyosin receptor kinase C (TrkC), and the neurotrophin-3 (NT-3) [...] Read more.
The neurobiology of schizophrenia is multifactorial, comprising the dysregulation of several biochemical pathways and molecules. This research proposes a peripheral biomarker for schizophrenia that involves the second extracellular loop of norepinephrine transporter (NEText), the tropomyosin receptor kinase C (TrkC), and the neurotrophin-3 (NT-3) in T cells. The study of NEText, NT-3, and TrkC was performed in T cells and plasma extracted from peripheral blood of 54 patients with schizophrenia and 54 healthy controls. Levels of NT-3, TrkC, and NET were significantly lower in plasma and T cells of patients compared to healthy controls. Co-immunoprecipitation (co-IPs) showed protein interactions with Co-IP NEText–NT-3 and Co-IP NEText–TrkC. Computational modelling of protein–peptide docking by CABS-dock provided a medium–high accuracy model for NT-3–NEText (4.6935 Å) and TrkC–NEText (2.1365 Å). In summary, immunocomplexes reached statistical relevance in the T cells of the control group contrary to the results obtained with schizophrenia. The reduced expression of NT-3, TrkC, and NET, and the lack of molecular complexes in T cells of patients with schizophrenia may lead to a peripheral dysregulation of intracellular signaling pathways and an abnormal reuptake of norepinephrine (NE) by NET. This peripheral molecular biomarker underlying schizophrenia reinforces the role of neurotrophins, and noradrenergic and immune systems in the pathophysiology of schizophrenia. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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12 pages, 3077 KiB  
Article
Evidence for Altered Phosphoinositide Signaling-Associated Molecules in the Postmortem Prefrontal Cortex of Patients with Schizophrenia
by Yasuto Kunii, Junya Matsumoto, Ryuta Izumi, Atsuko Nagaoka, Mizuki Hino, Risa Shishido, Makoto Sainouchi, Hiroyasu Akatsu, Yoshio Hashizume, Akiyoshi Kakita and Hirooki Yabe
Int. J. Mol. Sci. 2021, 22(15), 8280; https://doi.org/10.3390/ijms22158280 - 31 Jul 2021
Cited by 11 | Viewed by 2082
Abstract
Phosphoinositides (PIs) play important roles in the structure and function of the brain. Associations between PIs and the pathophysiology of schizophrenia have been studied. However, the significance of the PI metabolic pathway in the pathology of schizophrenia is unknown. We examined the expression [...] Read more.
Phosphoinositides (PIs) play important roles in the structure and function of the brain. Associations between PIs and the pathophysiology of schizophrenia have been studied. However, the significance of the PI metabolic pathway in the pathology of schizophrenia is unknown. We examined the expression of PI signaling-associated proteins in the postmortem brain of schizophrenia patients. Protein expression levels of phosphatidylinositol 4-phosphate 5-kinase type-1 gamma (PIP5K1C), phosphatidylinositol 4-kinase alpha (PIK4CA, also known as PIK4A), phosphatase and tensin homolog deleted from chromosome 10 (PTEN), protein kinase B (Akt), and glycogen synthase kinase 3β (GSK3β) were measured using enzyme-linked immunosorbent assays and multiplex fluorescent bead-based immunoassays of the prefrontal cortex (PFC) of postmortem samples from 23 schizophrenia patients and 47 normal controls. We also examined the association between PIK4CA expression and its genetic variants in the same brain samples. PIK4CA expression was lower, whereas Akt expression was higher, in the PFC of schizophrenia patients than in that of controls; PIP5K1C, PTEN, and GSK3β expression was not different. No single-nucleotide polymorphism significantly affected protein expression. We identified molecules involved in the pathology of schizophrenia via this lipid metabolic pathway. These results suggest that PIK4CA is involved in the mechanism underlying the pathogenesis of schizophrenia and is a potential novel therapeutic target. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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16 pages, 3338 KiB  
Article
Transcriptional Modulation of the Hippo Signaling Pathway by Drugs Used to Treat Bipolar Disorder and Schizophrenia
by Bruna Panizzutti, Chiara C. Bortolasci, Briana Spolding, Srisaiyini Kidnapillai, Timothy Connor, Mark F. Richardson, Trang T. T. Truong, Zoe S. J. Liu, Gerwyn Morris, Laura Gray, Jee Hyun Kim, Olivia M. Dean, Michael Berk and Ken Walder
Int. J. Mol. Sci. 2021, 22(13), 7164; https://doi.org/10.3390/ijms22137164 - 02 Jul 2021
Cited by 10 | Viewed by 3576
Abstract
Recent reports suggest a link between positive regulation of the Hippo pathway with bipolar disorder (BD), and the Hippo pathway is known to interact with multiple other signaling pathways previously associated with BD and other psychiatric disorders. In this study, neuronal-like NT2 cells [...] Read more.
Recent reports suggest a link between positive regulation of the Hippo pathway with bipolar disorder (BD), and the Hippo pathway is known to interact with multiple other signaling pathways previously associated with BD and other psychiatric disorders. In this study, neuronal-like NT2 cells were treated with amisulpride (10 µM), aripiprazole (0.1 µM), clozapine (10 µM), lamotrigine (50 µM), lithium (2.5 mM), quetiapine (50 µM), risperidone (0.1 µM), valproate (0.5 mM), or vehicle control for 24 h. Genome-wide mRNA expression was quantified and analyzed using gene set enrichment analysis (GSEA), with genes belonging to Hippo, Wnt, Notch, TGF- β, and Hedgehog retrieved from the KEGG database. Five of the eight drugs downregulated the genes of the Hippo pathway and modulated several genes involved in the interacting pathways. We speculate that the regulation of these genes, especially by aripiprazole, clozapine, and quetiapine, results in a reduction of MAPK and NFκB pro-inflammatory signaling through modulation of Hippo, Wnt, and TGF-β pathways. We also employed connectivity map analysis to identify compounds that act on these pathways in a similar manner to the known psychiatric drugs. Thirty-six compounds were identified. The presence of antidepressants and antipsychotics validates our approach and reveals possible new targets for drug repurposing. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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20 pages, 1059 KiB  
Article
Glutathione Deficiency during Early Postnatal Development Causes Schizophrenia-Like Symptoms and a Reduction in BDNF Levels in the Cortex and Hippocampus of Adult Sprague–Dawley Rats
by Marta Anna Lech, Monika Leśkiewicz, Kinga Kamińska, Zofia Rogóż and Elżbieta Lorenc-Koci
Int. J. Mol. Sci. 2021, 22(12), 6171; https://doi.org/10.3390/ijms22126171 - 08 Jun 2021
Cited by 14 | Viewed by 2144
Abstract
Growing body of evidence points to dysregulation of redox status in the brain as an important factor in the pathogenesis of schizophrenia. The aim of our study was to evaluate the effects of l-buthionine-(S,R)-sulfoximine (BSO), a glutathione (GSH) [...] Read more.
Growing body of evidence points to dysregulation of redox status in the brain as an important factor in the pathogenesis of schizophrenia. The aim of our study was to evaluate the effects of l-buthionine-(S,R)-sulfoximine (BSO), a glutathione (GSH) synthesis inhibitor, and 1-[2-Bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine dihydrochloride (GBR 12909), a dopamine reuptake inhibitor, given alone or in combination, to Sprague–Dawley pups during early postnatal development (p5–p16), on the time course of the onset of schizophrenia-like behaviors, and on the expression of brain-derived neurotrophic factor (BDNF) mRNA and its protein in the prefrontal cortex (PFC) and hippocampus (HIP) during adulthood. BSO administered alone decreased the levels of BDNF mRNA and its protein both in the PFC and HIP. Treatment with the combination of BSO + GBR 12909 also decreased BDNF mRNA and its protein in the PFC, but in the HIP, only the level of BDNF protein was decreased. Schizophrenia-like behaviors in rats were assessed at three time points of adolescence (p30, p42–p44, p60–p62) and in early adulthood (p90–p92) using the social interaction test, novel object recognition test, and open field test. Social and cognitive deficits first appeared in the middle adolescence stage and continued to occur into adulthood, both in rats treated with BSO alone or with the BSO + GBR 12909 combination. Behavior corresponding to positive symptoms in humans occurred in the middle adolescence period, only in rats treated with BSO + GBR 12909. Only in the latter group, amphetamine exacerbated the existing positive symptoms in adulthood. Our data show that rats receiving the BSO + GBR 12909 combination in the early postnatal life reproduced virtually all symptoms observed in patients with schizophrenia and, therefore, can be considered a valuable neurodevelopmental model of this disease. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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21 pages, 2263 KiB  
Article
Effects of Atypical Antipsychotics, Clozapine, Quetiapine and Brexpiprazole on Astroglial Transmission Associated with Connexin43
by Kouji Fukuyama and Motohiro Okada
Int. J. Mol. Sci. 2021, 22(11), 5623; https://doi.org/10.3390/ijms22115623 - 25 May 2021
Cited by 17 | Viewed by 2875
Abstract
Recently, accumulating preclinical findings suggest the possibility that functional abnormalities of tripartite synaptic transmission play important roles in the pathophysiology of schizophrenia and affective disorder. Therefore, to explore the novel mechanisms of mood-stabilizing effects associated with tripartite synaptic transmission, the present study determined [...] Read more.
Recently, accumulating preclinical findings suggest the possibility that functional abnormalities of tripartite synaptic transmission play important roles in the pathophysiology of schizophrenia and affective disorder. Therefore, to explore the novel mechanisms of mood-stabilizing effects associated with tripartite synaptic transmission, the present study determined the effects of mood-stabilizing antipsychotics, clozapine (CLZ), quetiapine (QTP) and brexpiprazole (BPZ), on the astroglial l-glutamate release and expression of connexin43 (Cx43) in the astroglial plasma membrane using cortical primary cultured astrocytes. Neither acute (for 120 min) nor subchronic (for 7 days) administrations of CLZ, QTP and BPZ affected basal astroglial l-glutamate release, whereas both acute and subchronic administration of CLZ, QTP and BPZ concentration-dependently enhanced astroglial l-glutamate release through activated hemichannels. Subchronic administration of therapeutic-relevant concentration of valproate (VPA), a histone deacetylase inhibiting mood-stabilizing antiepileptic drug, enhanced the stimulatory effects of therapeutic-relevant concentration of CLZ, QTP and BPZ on astroglial l-glutamate release through activated hemichannel. Subchronic administration of therapeutic-relevant concentration of CLZ, QTP and BPZ did not affect Cx43 protein expression in the plasma membrane during resting stage. After subchronic administration of VPA, acute and subchronic administration of therapeutic-relevant concentrations of CLZ increased Cx43 protein expression in the plasma membrane. Both acute administrations of therapeutic-relevant concentrations of QTP and BPZ did not affect, but subchronic administrations enhanced Cx43 protein expression in the astroglial plasma membrane. Furthermore, protein kinase B (Akt) inhibitor suppressed the stimulatory effects of CLZ and QTP, but did not affect Cx43 protein expression in the astroglial plasma membrane. These results suggest that three mood-stabilizing atypical antipsychotics, CLZ, QTP and BPZ enhance tripartite synaptic glutamatergic transmission due to enhancement of astroglial Cx43 containing hemichannel activities; however, the Cx43 activating mechanisms of these three mood-stabilizing antipsychotics were not identical. The enhanced astroglial glutamatergic transmission induced by CLZ, QTP and BPZ is, at least partially, involved in the actions of these three mood-stabilizing antipsychotics. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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19 pages, 1998 KiB  
Article
Towards Novel Treatments for Schizophrenia: Molecular and Behavioural Signatures of the Psychotropic Agent SEP-363856
by Veronica Begni, Alice Sanson, Alessia Luoni, Federica Sensini, Ben Grayson, Syeda Munni, Joanna C. Neill and Marco A. Riva
Int. J. Mol. Sci. 2021, 22(8), 4119; https://doi.org/10.3390/ijms22084119 - 16 Apr 2021
Cited by 27 | Viewed by 3133
Abstract
Schizophrenia is a complex psychopathology whose treatment is still challenging. Given the limitations of existing antipsychotics, there is urgent need for novel drugs with fewer side effects. SEP-363856 (SEP-856) is a novel psychotropic agent currently under phase III clinical investigation for schizophrenia treatment. [...] Read more.
Schizophrenia is a complex psychopathology whose treatment is still challenging. Given the limitations of existing antipsychotics, there is urgent need for novel drugs with fewer side effects. SEP-363856 (SEP-856) is a novel psychotropic agent currently under phase III clinical investigation for schizophrenia treatment. In this study, we investigated the ability of an acute oral SEP-856 administration to modulate the functional activity of specific brain regions at basal levels and under glutamatergic or dopaminergic-perturbed conditions in adult rats. We found that immediate-early genes (IEGs) expression was strongly upregulated in the prefrontal cortex and, to a less extent, in the ventral hippocampus, suggesting an activation of these regions. Furthermore, SEP-856 was effective in preventing the hyperactivity induced by an acute injection of phencyclidine (PCP), but not of d-amphetamine (AMPH). The compound effectively normalized the PCP-induced increase in IEGs expression in the PFC at all doses tested, whereas only the highest dose determined the major modulations on AMPH-induced changes. Lastly, SEP-856 acute administration corrected the cognitive deficits produced by subchronic PCP administration. Taken together, our data provide further insights on SEP-856, suggesting that modulation of the PFC may represent an important mechanism for the functional and behavioural activity of this novel compound. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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Review

Jump to: Research

21 pages, 21136 KiB  
Review
Modulation of Gut Microbial Diversity through Non-Pharmaceutical Approaches to Treat Schizophrenia
by Nayla Munawar, Aftab Ahmad, Munir Ahmad Anwar and Khalid Muhammad
Int. J. Mol. Sci. 2022, 23(5), 2625; https://doi.org/10.3390/ijms23052625 - 27 Feb 2022
Cited by 10 | Viewed by 4952
Abstract
Schizophrenia (SCZ) is a psychotic syndrome with well-defined signs and symptoms but indecisive causes and effective treatment. Unknown underpinning reasons and no cure of the disease profoundly elevate the risk of illness. Gut microbial dysbiosis related metabolic dysfunction is providing a new angle [...] Read more.
Schizophrenia (SCZ) is a psychotic syndrome with well-defined signs and symptoms but indecisive causes and effective treatment. Unknown underpinning reasons and no cure of the disease profoundly elevate the risk of illness. Gut microbial dysbiosis related metabolic dysfunction is providing a new angle to look at the potential causes and treatment options for schizophrenia. Because of the number of side effects, including gut dysbiosis, of traditional antipsychotic drugs, new alternative therapeutic options are under consideration. We propose that non-pharmacotherapy using biotherapeutic products could be a potent treatment to improve cognitive impairment and other symptoms of schizophrenia. Use of live microorganisms (probiotics), fibers (prebiotics), and polyphenols alone or in a mixture can maintain gut microbial diversity and improve the two-way relationship of the gut microbiota and the central nervous system. Fiber and polyphenol induced management of gut microbiota may positively influence the gut–brain axis by increasing the level of brain-derived neurotrophic factors involved in schizophrenia. Furthermore, we endorse the need for comprehensive clinical assessment and follow-up of psychobiotic (pro and prebiotics) treatment in mental illness to estimate the level of target recovery and disability reduction in schizophrenia. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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14 pages, 596 KiB  
Review
Is There a Link between Oropharyngeal Microbiome and Schizophrenia? A Narrative Review
by Stanislas Martin, Audrey Foulon, Wissam El Hage, Diane Dufour-Rainfray and Frédéric Denis
Int. J. Mol. Sci. 2022, 23(2), 846; https://doi.org/10.3390/ijms23020846 - 13 Jan 2022
Cited by 8 | Viewed by 4113
Abstract
The study aimed to examine the impact of the oropharyngeal microbiome in the pathophysiology of schizophrenia and to clarify whether there might be a bidirectional link between the oral microbiota and the brain in a context of dysbiosis-related neuroinflammation. We selected nine articles [...] Read more.
The study aimed to examine the impact of the oropharyngeal microbiome in the pathophysiology of schizophrenia and to clarify whether there might be a bidirectional link between the oral microbiota and the brain in a context of dysbiosis-related neuroinflammation. We selected nine articles including three systemic reviews with several articles from the same research team. Different themes emerged, which we grouped into 5 distinct parts concerning the oropharyngeal phageome, the oropharyngeal microbiome, the salivary microbiome and periodontal disease potentially associated with schizophrenia, and the impact of drugs on the microbiome and schizophrenia. We pointed out the presence of phageoma in patients suffering from schizophrenia and that periodontal disease reinforces the role of inflammation in the pathophysiology of schizophrenia. Moreover, saliva could be an interesting substrate to characterize the different stages of schizophrenia. However, the few studies we have on the subject are limited in scope, and some of them are the work of a single team. At this stage of knowledge, it is difficult to conclude on the existence of a bidirectional link between the brain and the oral microbiome. Future studies on the subject will clarify these questions that for the moment remain unresolved. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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28 pages, 2234 KiB  
Review
A Potential Interface between the Kynurenine Pathway and Autonomic Imbalance in Schizophrenia
by Alexandra Büki, Gabriella Kekesi, Gyongyi Horvath and László Vécsei
Int. J. Mol. Sci. 2021, 22(18), 10016; https://doi.org/10.3390/ijms221810016 - 16 Sep 2021
Cited by 6 | Viewed by 2936
Abstract
Schizophrenia is a neuropsychiatric disorder characterized by various symptoms including autonomic imbalance. These disturbances involve almost all autonomic functions and might contribute to poor medication compliance, worsened quality of life and increased mortality. Therefore, it has a great importance to find a potential [...] Read more.
Schizophrenia is a neuropsychiatric disorder characterized by various symptoms including autonomic imbalance. These disturbances involve almost all autonomic functions and might contribute to poor medication compliance, worsened quality of life and increased mortality. Therefore, it has a great importance to find a potential therapeutic solution to improve the autonomic disturbances. The altered level of kynurenines (e.g., kynurenic acid), as tryptophan metabolites, is almost the most consistently found biochemical abnormality in schizophrenia. Kynurenic acid influences different types of receptors, most of them involved in the pathophysiology of schizophrenia. Only few data suggest that kynurenines might have effects on multiple autonomic functions. Publications so far have discussed the implication of kynurenines and the alteration of the autonomic nervous system in schizophrenia independently from each other. Thus, the coupling between them has not yet been addressed in schizophrenia, although their direct common points, potential interfaces indicate the consideration of their interaction. The present review gathers autonomic disturbances, the impaired kynurenine pathway in schizophrenia, and the effects of kynurenine pathway on autonomic functions. In the last part of the review, the potential interaction between the two systems in schizophrenia, and the possible therapeutic options are discussed. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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23 pages, 446 KiB  
Review
Cognitive Deficit in Schizophrenia: From Etiology to Novel Treatments
by Antón L. Martínez, José Brea, Sara Rico, María Teresa de los Frailes and María Isabel Loza
Int. J. Mol. Sci. 2021, 22(18), 9905; https://doi.org/10.3390/ijms22189905 - 14 Sep 2021
Cited by 20 | Viewed by 5388
Abstract
Schizophrenia is a major mental illness characterized by positive and negative symptoms, and by cognitive deficit. Although cognitive impairment is disabling for patients, it has been largely neglected in the treatment of schizophrenia. There are several reasons for this lack of treatments for [...] Read more.
Schizophrenia is a major mental illness characterized by positive and negative symptoms, and by cognitive deficit. Although cognitive impairment is disabling for patients, it has been largely neglected in the treatment of schizophrenia. There are several reasons for this lack of treatments for cognitive deficit, but the complexity of its etiology—in which neuroanatomic, biochemical and genetic factors concur—has contributed to the lack of effective treatments. In the last few years, there have been several attempts to develop novel drugs for the treatment of cognitive impairment in schizophrenia. Despite these efforts, little progress has been made. The latest findings point to the importance of developing personalized treatments for schizophrenia which enhance neuroplasticity, and of combining pharmacological treatments with non-pharmacological measures. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
22 pages, 2580 KiB  
Review
Pharmaco-Magnetic Resonance as a Tool for Monitoring the Medication-Related Effects in the Brain May Provide Potential Biomarkers for Psychotic Disorders
by Katrin Aryutova and Drozdstoy Stoyanov
Int. J. Mol. Sci. 2021, 22(17), 9309; https://doi.org/10.3390/ijms22179309 - 27 Aug 2021
Cited by 4 | Viewed by 3890
Abstract
The neurodegenerative and neurodevelopmental hypotheses represent the basic etiological framework for the origin of schizophrenia. Additionally, the dopamine hypothesis, adopted more than two decades ago, has repeatedly asserted the position of dopamine as a pathobiochemical substrate through the action of psychostimulants and neuroleptics [...] Read more.
The neurodegenerative and neurodevelopmental hypotheses represent the basic etiological framework for the origin of schizophrenia. Additionally, the dopamine hypothesis, adopted more than two decades ago, has repeatedly asserted the position of dopamine as a pathobiochemical substrate through the action of psychostimulants and neuroleptics on the mesolimbic and mesocortical systems, giving insight into the origin of positive and negative schizophrenic symptoms. Meanwhile, cognitive impairments in schizophrenia remain incompletely understood but are thought to be present during all stages of the disease, as well as in the prodromal, interictal and residual phases. On the other hand, observations on the effects of NMDA antagonists, such as ketamine and phencyclidine, reveal that hypoglutamatergic neurotransmission causes not only positive and negative but also cognitive schizophrenic symptoms. This review aims to summarize the different hypotheses about the origin of psychoses and to identify the optimal neuroimaging method that can serve to unite them in an integral etiological framework. We systematically searched Google scholar (with no concern to the date published) to identify studies investigating the etiology of schizophrenia, with a focus on impaired central neurotransmission. The complex interaction between the dopamine and glutamate neurotransmitter systems provides the long-needed etiological concept, which combines the neurodegenerative hypothesis with the hypothesis of impaired neurodevelopment in schizophrenia. Pharmaco-magnetic resonance imaging is a neuroimaging method that can provide a translation of scientific knowledge about the neural networks and the disruptions in and between different brain regions, into clinically applicable and effective therapeutic results in the management of severe psychotic disorders. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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19 pages, 837 KiB  
Review
Cellular Models in Schizophrenia Research
by Dmitrii A. Abashkin, Artemii O. Kurishev, Dmitry S. Karpov and Vera E. Golimbet
Int. J. Mol. Sci. 2021, 22(16), 8518; https://doi.org/10.3390/ijms22168518 - 07 Aug 2021
Cited by 7 | Viewed by 4246
Abstract
Schizophrenia (SZ) is a prevalent functional psychosis characterized by clinical behavioural symptoms and underlying abnormalities in brain function. Genome-wide association studies (GWAS) of schizophrenia have revealed many loci that do not directly identify processes disturbed in the disease. For this reason, the development [...] Read more.
Schizophrenia (SZ) is a prevalent functional psychosis characterized by clinical behavioural symptoms and underlying abnormalities in brain function. Genome-wide association studies (GWAS) of schizophrenia have revealed many loci that do not directly identify processes disturbed in the disease. For this reason, the development of cellular models containing SZ-associated variations has become a focus in the post-GWAS research era. The application of revolutionary clustered regularly interspaced palindromic repeats CRISPR/Cas9 gene-editing tools, along with recently developed technologies for cultivating brain organoids in vitro, have opened new perspectives for the construction of these models. In general, cellular models are intended to unravel particular biological phenomena. They can provide the missing link between schizophrenia-related phenotypic features (such as transcriptional dysregulation, oxidative stress and synaptic dysregulation) and data from pathomorphological, electrophysiological and behavioural studies. The objectives of this review are the systematization and classification of cellular models of schizophrenia, based on their complexity and validity for understanding schizophrenia-related phenotypes. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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31 pages, 2211 KiB  
Review
Hidden Role of Gut Microbiome Dysbiosis in Schizophrenia: Antipsychotics or Psychobiotics as Therapeutics?
by Nayla Munawar, Khansa Ahsan, Khalid Muhammad, Aftab Ahmad, Munir A. Anwar, Iltaf Shah, Ahlam Khalifa Al Ameri and Fadwa Al Mughairbi
Int. J. Mol. Sci. 2021, 22(14), 7671; https://doi.org/10.3390/ijms22147671 - 18 Jul 2021
Cited by 30 | Viewed by 10192
Abstract
Schizophrenia is a chronic, heterogeneous neurodevelopmental disorder that has complex symptoms and uncertain etiology. Mounting evidence indicates the involvement of genetics and epigenetic disturbances, alteration in gut microbiome, immune system abnormalities, and environmental influence in the disease, but a single root cause and [...] Read more.
Schizophrenia is a chronic, heterogeneous neurodevelopmental disorder that has complex symptoms and uncertain etiology. Mounting evidence indicates the involvement of genetics and epigenetic disturbances, alteration in gut microbiome, immune system abnormalities, and environmental influence in the disease, but a single root cause and mechanism involved has yet to be conclusively determined. Consequently, the identification of diagnostic markers and the development of psychotic drugs for the treatment of schizophrenia faces a high failure rate. This article surveys the etiology of schizophrenia with a particular focus on gut microbiota regulation and the microbial signaling system that correlates with the brain through the vagus nerve, enteric nervous system, immune system, and production of postbiotics. Gut microbially produced molecules may lay the groundwork for further investigations into the role of gut microbiota dysbiosis and the pathophysiology of schizophrenia. Current treatment of schizophrenia is limited to psychotherapy and antipsychotic drugs that have significant side effects. Therefore, alternative therapeutic options merit exploration. The use of psychobiotics alone or in combination with antipsychotics may promote the development of novel therapeutic strategies. In view of the individual gut microbiome structure and personalized response to antipsychotic drugs, a tailored and targeted manipulation of gut microbial diversity naturally by novel prebiotics (non-digestible fiber) may be a successful alternative therapeutic for the treatment of schizophrenia patients. Full article
(This article belongs to the Special Issue Molecular Mechanisms of Schizophrenia and Novel Targets)
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