Vortioxetine Reduces Marble Burying but Only Transiently Enhances Social Interaction Preference in Adult Male BTBR T+Itpr3tf/J Mice

Vortioxetine improved schizophrenia-like behavioral deficits in a Poly I:C-induced maternal immune activation model of schizophrenia in rats

BACKGROUND

Several studies provide clear evidence that exposure to various infections during pregnancy are linked with an increased risk for schizophrenia. In preclinical studies, administration of polyinosinic-polycytidylic acid (Poly I:C) in pregnant rodents can induce maternal immune activation leading to impairments in brain function in the offspring.

OBJECTIVES

The aim of this study was to investigate the effect of vortioxetine, a multimodal selective serotonin reuptake inhibitor (SSRI), in the pathophysiology of Poly I:C-induced schizophrenia-like model in rats.

METHODS

For this purpose, Poly I:C (8 mg/kg, ip) was injected into pregnant animals 14 days after mating, and tail blood was taken for determination of IL-6 levels after 2 h. At postnatal days 83-86, behavioral tests were performed.

RESULTS

Our results revealed that Poly I:C caused impairments in prepulse inhibition, novel object recognition, social interaction, and open-field tests. Chronic administration of vortioxetine (2.5, 5, and 10 mg/kg, ip, postnatal days 69-83) caused significant improvements in these deficits.

CONCLUSION

Overall, our findings indicate that vortioxetine may provide new therapeutic approaches for the treatment of schizophrenia. We think that increased serotonergic activity in frontal brain regions may provide the ameliorative effect of vortioxetine, especially on negative and cognitive symptoms. Therefore, it will be useful to determine the efficacy of vortioxetine with combined drugs with further studies.

Effects of different types of induced neonatal inflammation on development and behavior of C57BL/6 and BTBR mice

Neuroinflammation in the early postnatal period can disturb trajectories of the completion of normal brain development and can lead to mental illnesses, such as depression, anxiety disorders, and personality disorders later in life. In our study, we focused on evaluating short- and long-term effects of neonatal inflammation induced by lipopolysaccharide, poly(I:C), or their combination in female and male C57BL/6 and BTBR mice. We chose the BTBR strain as potentially more susceptible to neonatal inflammation because these mice have behavioral, neuroanatomical, and physiological features of autism spectrum disorders, an abnormal immune response, and several structural aberrations in the brain. Our results indicated that BTBR mice are more sensitive to the influence of the neonatal immune activation (NIA) on the formation of neonatal reflexes than C57BL/6 mice are. In these experiments, the injection of lipopolysaccharide had an effect on the formation of the cliff aversion reflex in female BTBR mice. Nonetheless, NIA had no delayed effects on either social behavior or anxiety-like behavior in juvenile and adolescent BTBR and C57BL/6 mice. Altogether, our data show that NIA has mimetic-, age-, and strain-dependent effects on the development of neonatal reflexes and on exploratory activity in BTBR and C57BL/6 mice.

The brain serotonin system in autism

Autism spectrum disorders (ASDs) are among the most common neurodevelopmental diseases. These disorders are characterized by lack of social interaction, by repetitive behavior, and often anxiety and learning disabilities. The brain serotonin (5-HT) system is known to be crucially implicated in a wide range of physiological functions and in the control of different kinds of normal and pathological behavior. A growing number of studies indicate the involvement of the brain 5-HT system in the mechanisms underlying both ASD development and ASD-related behavioral disorders. There are some review papers describing the role of separate key players of the 5-HT system in an ASD and/or autistic-like behavior. In this review, we summarize existing data on the participation of all members of the brain 5-HT system, namely, 5-HT transporter, tryptophan hydroxylase 2, MAOA, and 5-HT receptors, in autism in human and various animal models. Additionally, we describe the most recent studies involving modern techniques for in vivo regulation of gene expression that are aimed at identifying exact roles of 5-HT receptors, MAOA, and 5-HT transporter in the mechanisms underlying autistic-like behavior. Altogether, results of multiple research articles show that the brain 5-HT system intimately partakes in the control of some types of ASD-related behavior, and that specific changes in a function of a certain 5-HT receptor, transporter, and/or enzyme may normalize this aberrant behavior. These data give hope that some of clinically used 5-HT-related drugs have potential for ASD treatment.

Vortioxetine improved negative and cognitive symptoms of schizophrenia in subchronic MK-801 model in rats

Schizophrenia is a devastating psychiatric disorder with complex symptoms and neurobiology. Serotonergic dysregulation is known to contribute to the pathogenesis of schizophrenia although dopaminergic and glutamatergic systems are thought to have central roles in neurobiology. No significant success can be achieved in the treatment of negative and cognitive symptoms while positive symptoms can be significantly reduced with current pharmacotherapy. Vortioxetine is a new multimodal antidepressant with 5-HT1A agonism, 5-HT1B partial agonism, 5-HT3, 5-HT7, and 5-HT1D antagonism, and serotonin reuptake inhibition. A limited number of studies suggest its therapeutic effect on the negative and cognitive symptoms of schizophrenia. Therefore, we investigated the potential beneficial effects of vortioxetine on behavioral and molecular deficits in the MK-801 model of schizophrenia in rats. Female Wistar albino rats (10-12 weeks) were grouped as saline, MK-801 (0.2 mg/kg), MK-801 + vortioxetine (2.5 mg/kg), MK-801 + vortioxetine (5 mg/kg), MK-801 + vortioxetine (10 mg/kg), MK-801 + risperidone (0.3 mg/kg), MK-801 + haloperidol (1 mg/kg) (n = 8 in each group). MK-801 has been daily administered (i.p.) for 14 days. Vortioxetine and antipsychotic treatments were injected for 21 days after a washout period of MK-801 and locomotor activity (LA), social interaction (SI), novel object recognition (NOR), Y-maze and prepulse inhibition (PPI) tests were performed at the 16-20th days of treatments, respectively. ELISA test was conducted to evaluate molecular analyses. MK-801 decreased PPI (%), social behaviors, and discrimination index in NOR and alternation (%) in the Y-maze test. In NOR and Y-maze tests, especially vortioxetine 5 and 10 mg/kg increased discrimination index and alternation (%) compared to MK-801. In addition, vortioxetine administration increased social behaviors. Moreover, MK-801 decreased GAD67 and parvalbumin levels while vortioxetine increased these protein levels compared to MK-801. Herein, we first suggested a potential therapeutic effect of vortioxetine, a new multimodal antidepressant, on negative and cognitive symptoms and neurobiological deficits including GAD67 and parvalbumin low expression in the MK-801 model in rats. It would be beneficial to confirm our results in different rodent models and to shed light on the possible mechanisms underlying these effects.

The live biotherapeutic Blautia stercoris MRx0006 attenuates social deficits, repetitive behaviour, and anxiety-like behaviour in a mouse model relevant to autism

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterised by deficits in social behaviour, increased repetitive behaviour, anxiety and gastrointestinal symptoms. The aetiology of ASD is complex and involves an interplay of genetic and environmental factors. Emerging pre-clinical and clinical studies have documented a potential role for the gut microbiome in ASD, and consequently, the microbiota represents a potential target in the development of novel therapeutics for this neurodevelopmental disorder. In this study, we investigate the efficacy of the live biotherapeutic strain, Blautia stercoris MRx0006, in attenuating some of the behavioural deficits in the autism-relevant, genetic mouse model, BTBR T+ Itpr3tf/J (BTBR). We demonstrate that daily oral administration with MRx0006 attenuates social deficits while also decreasing repetitive and anxiety-like behaviour. MRx0006 administration increases the gene expression of oxytocin and its receptor in hypothalamic cells in vitro and increases the expression of hypothalamic arginine vasopressin and oxytocin mRNA in BTBR mice. Additionally at the microbiome level, we observed that MRx0006 administration decreases the abundance of Alistipes putredinis, and modulates the faecal microbial metabolite profile. This alteration in the metabolite profile possibly underlies the observed increase in expression of oxytocin, arginine vasopressin and its receptors, and the consequent improvements in behavioural outcomes. Taken together, these findings suggest that the live biotherapeutic MRx0006 may represent a viable and efficacious treatment option for the management of physiological and behavioural deficits associated with ASD.

Chemical Modulators for Targeting Autism Spectrum Disorders: From Bench to Clinic

Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by diverse behavioral symptoms such as repetitive behaviors, social deficits, anxiety, hyperactivity, and irritability. Despite their increasing incidence, the specific pathological mechanisms of ASD are still unknown, and the degree and types of symptoms that vary from patient to patient make it difficult to develop drugs that target the core symptoms of ASD. Although various atypical antipsychotics and antidepressants have been applied to regulate ASD symptoms, these drugs can only alleviate the symptoms and do not target the major causes. Therefore, development of novel drugs targeting factors directly related to the onset of ASD is required. Among the various factors related to the onset of ASD, several chemical modulators to treat ASD, focused on serotonin (5-hydroxytryptamine, 5-HT) and glutamate receptors, microbial metabolites, and inflammatory cytokines, are explored in this study. In particular, we focus on the chemical drugs that have improved various aspects of ASD symptoms in animal models and in clinical trials for various ages of patients with ASD.

Ketamine administration in early postnatal life as a tool for mimicking Autism Spectrum Disorders core symptoms

Autism Spectrum Disorders (ASD) core symptoms include deficits of social interaction, stereotyped behaviours, dysfunction in language and communication. Beyond them, several additional symptoms, such as cognitive impairment, anxiety-like states and hyperactivity are often occurring, mainly overlapping with other neuropsychiatric diseases. To untangle mechanisms underlying ASD etiology, and to identify possible pharmacological approaches, different factors, such as environmental, immunological and genetic ones, need to be considered. In this context, ASD animal models, aiming to reproduce the wide range of behavioural phenotypes of this uniquely human disorder, represent a very useful tool. Ketamine administration in early postnatal life of mice has already been studied as a suitable animal model resembling psychotic-like symptoms. Here, we investigated whether ketamine administration, at postnatal days 7, 9 and 11, might induce behavioural features able to mimic ASD typical symptoms in adult mice. To this aim, we developed a 4-days behavioural tests battery, including Marble Burying, Hole Board, Olfactory and Social tests, to assess repetitive and stereotyped behaviour, social deficits and anxiety-like symptoms. Moreover, by using this mouse model, we performed neurochemical and biomolecular analyses, quantifying neurotransmitters belonging to excitatory-inhibitory pathways, such as glutamate, glutamine and gamma-aminobutyric acid (GABA), as well as immune activation biomarkers related to ASD, such as CD11b and glial fibrillary acidic protein (GFAP), in the hippocampus and amygdala. Possible alterations in levels of brain-derived neurotrophic factor (BDNF) expression in the hippocampus and amygdala were also evaluated. Our results showed an increase in stereotyped behaviours, together with social impairments and anxiety-like behaviour in adult mice, receiving ketamine administration in early postnatal life. In addition, we found decreased BDNF and enhanced GFAP hippocampal expression levels, accompanied by elevations in glutamate amount, as well as reduction in GABA content in amygdala and hippocampus. In conclusion, early ketamine administration may represent a suitable animal model of ASD, exhibiting face validity to mimic specific ASD symptoms, such as social deficits, repetitive repertoire and anxiety-like behaviour.

Serotonin Receptors as Therapeutic Targets for Autism Spectrum Disorder Treatment

Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders characterized by repetitive and stereotyped behaviors as well as difficulties with social interaction and communication. According to reports for prevalence rates of ASD, approximately 1~2% of children worldwide have been diagnosed with ASD. Although there are a couple of FDA (Food and Drug Administration)—approved drugs for ASD treatment such as aripiprazole and risperidone, they are efficient for alleviating aggression, hyperactivity, and self-injury but not the core symptoms. Serotonin (5-hydroxytryptamine, 5-HT) as a neurotransmitter plays a crucial role in the early neurodevelopmental stage. In particular, 5-HT has been known to regulate a variety of neurobiological processes including neurite outgrowth, dendritic spine morphology, shaping neuronal circuits, synaptic transmission, and synaptic plasticity. Given the roles of serotonergic systems, the 5-HT receptors (5-HTRs) become emerging as potential therapeutic targets in the ASD. In this review, we will focus on the recent development of small molecule modulators of 5-HTRs as therapeutic targets for the ASD treatment.

Behavioral, Anti-Inflammatory, and Neuroprotective Effects of a Novel FPR2 Agonist in Two Mouse Models of Autism

Autism spectrum disorders (ASD) are a group of heterogeneous neurodevelopmental conditions characterized by social deficits, repetitive stereotyped behaviors, and altered inflammatory responses. Accordingly, children with ASD show decreased plasma levels of lipoxin A4 (LXA4), a mediator involved in the resolution of inflammation, which is the endogenous ligand of the formyl peptide receptor 2 (FPR2). To investigate the role of FPR2 in ASDs, we have used a new ureidopropanamide derivative able to activate the receptor, named MR-39. The effects of MR-39 (10 mg/kg, for 8 days) on hippocampal pro-inflammatory profile, neuronal plasticity, and social behavior were evaluated in two validated animal models of ASD: BTBR mouse strain and mice prenatally exposed to valproic acid (VPA). Primary cultures of hippocampal neurons from BTBR mice were also used to evaluate the effect of MR-39 on neurite elongation. Our results show that MR-39 treatment reduced several inflammatory markers, restored the low expression of LXA4, and modulated FPR2 expression in hippocampal tissues of both ASD animal models. These findings were accompanied by a significant positive effect of MR-39 on social behavioral tests of ASD mice. Finally, MR-39 stimulates neurite elongation in isolated hippocampal neurons of BTBR mice. In conclusion, these data indicate FPR2 as a potential target for an innovative therapeutical approach for the cure of ASD.

Sex-specific behavioral and structural alterations caused by early-life stress in C57BL/6 and BTBR mice

Lately, the development of various mental illnesses, such as depression, personality disorders, and autism spectrum disorders, is often associated with traumatic events in childhood. Nonetheless, the mechanism giving rise to this predisposition is still unknown. Because the development of a disease often depends on a combination of a genetic background and environment, we decided to evaluate the effect of early-life stress on BTBR mice, which have behavioral, neuroanatomical, and physiological features of autism spectrum disorders. As early-life stress, we used prolonged separation of pups from their mothers in the first 2 weeks of life (3 h once a day). We assessed effects of the early-life stress on juvenile (postnatal day 23) and adolescent (postnatal days 37-38) male and female mice of strains C57BL/6 (B6) and BTBR. We found that in both strains, the early-life stress did not lead to changes in the level of social behavior, which is an important characteristic of autism-related behavior. Nonetheless, the early-life stress resulted in increased locomotor activity in juvenile BTBR mice. In adolescent mice, the stress early in life caused a low level of anxiety in B6 males and BTBR females and increased exploratory activity in adolescent BTBR males and females. In addition, adolescent B6 male and female mice with a history of the early-life stress tended to have a thinner motor cortex as assessed by magnetic resonance imaging. As compared to B6 mice, BTBR mice showed reduced levels of social behavior and exploratory activity but their level of locomotor activity was higher. BTBR mice had smaller whole-brain, cortical, and dorsal hippocampal volumes; decreased motor cortex thickness; and increased ventral-hippocampus volume as compared to B6 mice, and these parameters correlated with the level of exploratory behavior of BTBR mice. Overall, the effects of early postnatal stress are sex- and strain-dependent.

Hippocampal PPARα Plays a Role in the Pharmacological Mechanism of Vortioxetine, a Multimodal-Acting Antidepressant

As a well-known multimodal-acting antidepressant, vortioxetine is thought to aim at several serotonin (5-HT) receptors and the 5-HT transporter. However, recently more and more proteins besides 5-HT are being reported to participate in the antidepressant mechanism of vortioxetine. As a widely known nuclear hormone receptor, peroxisome proliferator activated receptor α (PPARα) possesses transcriptional activity and is very important in the brain. Several reports have suggested that hippocampal PPARα is implicated in antidepressant responses. Here we speculate that hippocampal PPARα may participate in the antidepressant mechanism of vortioxetine. In this study, chronic unpredictable mild stress (CUMS), chronic social defeat stress (CSDS), behavioral tests, the western blotting and adenovirus associated virus (AAV)-mediated gene knockdown methods were used together. It was found that vortioxetine administration significantly reversed the inhibitory actions of both CUMS and CSDS on the hippocampal PPARα expression. Pharmacological blockade of PPARα notably prevented the antidepressant actions of vortioxetine in the CUMS and CSDS models. Moreover, genetic knockdown of PPARα in the hippocampus also significantly blocked the protecting effects of vortioxetine against both CUMS and CSDS. Therefore, the antidepressant effects of vortioxetine in mice require hippocampal PPARα.

Knowledge-Based Design of Long-Chain Arylpiperazine Derivatives Targeting Multiple Serotonin Receptors as Potential Candidates for Treatment of Autism Spectrum Disorder

Autism spectrum disorder (ASD) includes a group of neurodevelopmental disorders characterized by core symptoms such as impaired social interaction and communication, repetitive and stereotyped behaviors, and restricted interests. To date, there are no effective treatments for these core symptoms. Several studies have shown that the brain serotonin (5-HT) neurotransmission system is altered in both ASD patients and animal models of the disease. Multiple pieces of evidence suggest that targeting 5-HT receptors may treat the core symptoms of ASD and associated intellectual disabilities. In fact, stimulation of the 5-HT_1A receptor reduces repetitive and restricted behaviors; blockade of the 5-HT_2A receptor reduces both learning deficits and repetitive behavior, and activation of the 5-HT₇ receptor improves cognitive performances and reduces repetitive behavior. On such a basis, we have designed novel arylpiperazine derivatives pursuing unprecedently reported activity profiles: dual 5-HT₇/5-HT_1A receptor agonist properties and mixed 5-HT₇ agonist/5-HT_1A agonist/5-HT_2A antagonist properties. Seventeen new compounds were synthesized and tested in radioligand binding assay at the target receptors. We have identified the dual 5-HT_1AR/5-HT₇R agonists 8c and 29 and the mixed 5-HT_1AR agonist/5-HT₇R agonist/5-HT_2AR antagonist 20b. These compounds are metabolically stable in vitro and have suitable central nervous system druglike properties.

Serotonergic Neurotransmission System Modulator, Vortioxetine, and Dopaminergic D2/D3 Receptor Agonist, Ropinirole, Attenuate Fibromyalgia-Like Symptoms in Mice

Fibromyalgia is a disease characterized by lowered pain threshold, mood disorders, and decreased muscular strength. It results from a complex dysfunction of the nervous system and due to unknown etiology, its diagnosis, treatment, and prevention are a serious challenge for contemporary medicine. Impaired serotonergic and dopaminergic neurotransmission are regarded as key factors contributing to fibromyalgia. The present research assessed the effect of serotonergic and dopaminergic system modulators (vortioxetine and ropinirole, respectively) on the pain threshold, depressive-like behavior, anxiety, and motor functions of mice with fibromyalgia-like symptoms induced by subcutaneous reserpine (0.25 mg/kg). By depleting serotonin and dopamine in the mouse brain, reserpine induced symptoms of human fibromyalgia. Intraperitoneal administration of vortioxetine and ropinirole at the dose of 10 mg/kg alleviated tactile allodynia. At 5 and 10 mg/kg ropinirole showed antidepressant-like properties, while vortioxetine had anxiolytic-like properties. None of these drugs influenced muscle strength but reserpine reduced locomotor activity of mice. Concluding, in the mouse model of fibromyalgia vortioxetine and ropinirole markedly reduced pain. These drugs affected emotional processes of mice in a distinct manner. Hence, these two repurposed drugs should be considered as potential drug candidates for fibromyalgia. The selection of a specific drug should depend on patient’s key symptoms.

Neonatal curcumin treatment restores hippocampal neurogenesis and improves autism-related behaviors in a mouse model of autism

RATIONALE

Autism spectrum disorders (ASDs) are highly prevalent neurodevelopmental disorders characterized by deficits in social communication and interaction, repetitive stereotyped behaviors, and cognitive impairments. Curcumin has been indicated to be neuroprotective against neurological and psychological disorders. However, the role of curcumin in autistic phenotypes remains unclear.

OBJECTIVES

In the current study, we evaluated the effects of neonatal curcumin treatment on behavior and hippocampal neurogenesis in BTBRT⁺ltpr3^tf/J (BTBR) mice, a model of autism.

METHODS

C57BL/6J (C57) and BTBR mouse pups were treated with 0.1% dimethyl sulfoxide (DMSO) or curcumin (20 mg/kg) from postnatal day 6 (P6) to P8. Neural progenitor cells (NPCs) in the hippocampal dentate gyrus (DG) were evaluated on P8, and neurogenesis was measured on P24 by immunofluorescence. A battery of behavioral tests was carried out when the mice were 8 weeks of age.

RESULTS

Neonatal curcumin treatment improved autism-related symptoms in BTBR mice, enhancing sociability, reducing repetitive behaviors, and ameliorating cognitive impairments. Furthermore, the suppression of hippocampal neurogenesis in BTBR mice was greatly rescued after neonatal curcumin treatment, leading to an increase in neurogenic processes and an increase in NPC proliferation concomitant with an expansion of the NPC pool on P8, and NPC differentiation towards the neuronal lineage was promoted in the DG of BTBR mice on P24.

CONCLUSIONS

Our findings suggest that neonatal curcumin treatment elicits a therapeutic response through the restoration of hippocampal neurogenesis in BTBR mice and thus may represent a promising novel pharmacological strategy for ASD treatment.