New directions in the treatment of autism spectrum disorders from animal model research

Amygdalar neurotransmission alterations in the BTBR mice model of idiopathic autism

Autism Spectrum Disorders (ASD) are principally diagnosed by three core behavioural symptoms, such as stereotyped repertoire, communication impairments and social dysfunctions. This complex pathology has been linked to abnormalities of corticostriatal and limbic circuits. Despite experimental efforts in elucidating the molecular mechanisms behind these abnormalities, a clear etiopathogenic hypothesis is still lacking. To this aim, preclinical studies can be really helpful to longitudinally study behavioural alterations resembling human symptoms and to investigate the underlying neurobiological correlates. In this regard, the BTBR T+ Itpr3tf/J (BTBR) mice are an inbred mouse strain that exhibits a pattern of behaviours well resembling human ASD-like behavioural features. In this study, the BTBR mice model was used to investigate neurochemical and biomolecular alterations, regarding Nerve Growth Factor (NGF) and Brain-Derived Neurotrophic Factor (BDNF), together with GABAergic, glutamatergic, cholinergic, dopaminergic and noradrenergic neurotransmissions and their metabolites in four different brain areas, i.e. prefrontal cortex, hippocampus, amygdala and hypothalamus. In our results, BTBR strain reported decreased noradrenaline, acetylcholine and GABA levels in prefrontal cortex, while hippocampal measurements showed reduced NGF and BDNF expression levels, together with GABA levels. Concerning hypothalamus, no differences were retrieved. As regarding amygdala, we found reduced dopamine levels, accompanied by increased dopamine metabolites in BTBR mice, together with decreased acetylcholine, NGF and GABA levels and enhanced glutamate content. Taken together, our data showed that the BTBR ASD model, beyond its face validity, is a useful tool to untangle neurotransmission alterations that could be underpinned to the heterogeneous ASD-like behaviours, highlighting the crucial role played by amygdala.

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.

Quantification of perfusion and metabolism in an autism mouse model assessed by diffuse correlation spectroscopy and near-infrared spectroscopy

There is a need for quantitative biomarkers for early diagnosis of autism. Cerebral blood flow and oxidative metabolism parameters may show superior contrasts for improved characterization. Diffuse correlation spectroscopy (DCS) has been shown to be reliable method to obtain cerebral blood flow contrast in animals and humans. Thus, in this study, we evaluated the combination of DCS and fNIRS in an established autism mouse model. Our results indicate that autistic group had significantly (P = .001) lower (~40%) blood flow (1.16 ± 0.26) × 10^-8  cm² /s), and significantly (P = .015) lower (~70%) oxidative metabolism (52.4 ± 16.6 μmol/100 g/min) compared to control group ([1.93 ± 0.74] × 10^-8  cm² /s, 177.2 ± 45.8 μmol/100 g/min, respectively). These results suggest that the combination of DCS and fNIRS can provide hemodynamic and metabolic contrasts for in vivo assessment of autism pathological conditions noninvasively.

Sodium phenylbutyrate reduces repetitive self-grooming behavior and rescues social and cognitive deficits in mouse models of autism

Autism spectrum disorder (ASD) is a neurodevelopment disorder characterized by deficits in social interaction and restrictive, repetitive, and stereotypical patterns of behavior. However, there is no pharmacological drug that is currently used to target these core ASD symptoms. Sodium phenylbutyrate (NaPB) is a well-known long-term treatment of urea cycle disorders in children. In this study, we assessed the therapeutic effects of NaPB, which is a chemical chaperone as well as histone deacetylase inhibitor on a BTBR T + Itpr3tf/J (BTBR) mice model of ASD. We found that acute and chronic treatment of NaPB remarkably improved, not only core ASD symptoms, including repetitive behaviors and sociability deficit, but also cognitive impairment in the BTBR mice. NaPB substantially induced histone acetylation in the brain of the BTBR mice. Intriguingly, the therapeutic effects of NaPB on autistic-like behaviors, such as repetitive behaviors, impaired sociability, and cognitive deficit also showed in the valproic acid (VPA)-induced mouse model of autism. In addition, pentylenetetrazole (PTZ)-induced seizure was significantly attenuated by NaPB treatment in C57BL/6J and BTBR mice. These findings suggest that NaPB may provide a novel therapeutic approach for the treatment of patients with ASD.

Association between autism spectrum disorder and polymorphisms in genes encoding serotine and dopamine receptors

Dysfunctions of the neurotransmitter system are related to the development of many psychological diseases including autism spectrum disorder (ASD). Single nucleotide polymorphisms (SNPs) are correlated with varied susceptibility of ASD and response to treatments. The association between SNPs in genes encoding serotonin and dopamine receptors and childhood ASD was examined in a Chinese Han population. Both autistic children (n = 319) and age-and gender-matched healthy controls (n = 347) were recruited from a local district. Disease severity was evaluated by the childhood autism rating scale (CARS). SNPs of rs6311 and rs6313 in the serotonin receptor HTR2A gene, rs4630328 in the dopamine receptor D2 (DRD2) gene and rs167771 in the DRD3 gene were examined. The CC genotype of rs6311 was significantly associated with an increased risk of ASD (odds ratio (OD) = 1.8 vs TT, 95% confidence interval (CI): 1.2-2.8, P = 0.0085). Carriers of the C allele of rs6311 had a significantly higher risk of childhood ASD (OD =1.3, 95% CI = 1.1-1.7, P = 0.0094). A strong linkage disequilibrium was observed between rs6311 and rs6313 (D' = 0.93, r² = 0.86). There were significant correlations between haplotypes (T-A and C-G of rs6311-rs6313) and risk of childhood ASD. In contrast, the frequencies of genotypes and alleles of rs6313, rs4630328 and rs167771 were not significantly different between the case and control groups. All the SNPs examined were not associated with severity of the disease. Our study demonstrates that certain SNPs in the HTR2A gene, but not the DRD2 and DRD3, are associated with susceptibility to childhood ASD.

Dysfunctional d-aspartate metabolism in BTBR mouse model of idiopathic autism

BACKGROUND

Autism spectrum disorders (ASD) comprise a heterogeneous group of neurodevelopmental conditions characterized by impairment in social interaction, deviance in communication, and repetitive behaviors. Dysfunctional ionotropic NMDA and AMPA receptors, and metabotropic glutamate receptor 5 activity at excitatory synapses has been recently linked to multiple forms of ASD. Despite emerging evidence showing that d-aspartate and d-serine are important neuromodulators of glutamatergic transmission, no systematic investigation on the occurrence of these D-amino acids in preclinical ASD models has been carried out.

METHODS

Through HPLC and qPCR analyses we investigated d-aspartate and d-serine metabolism in the brain and serum of four ASD mouse models. These include BTBR mice, an idiopathic model of ASD, and Cntnap2^-/-, Shank3^-/-, and 16p11.2^+/- mice, three established genetic mouse lines recapitulating high confidence ASD-associated mutations.

RESULTS

Biochemical and gene expression mapping in Cntnap2^-/-, Shank3^-/-, and 16p11.2^+/- failed to find gross cerebral and serum alterations in d-aspartate and d-serine metabolism. Conversely, we found a striking and stereoselective increased d-aspartate content in the prefrontal cortex, hippocampus and serum of inbred BTBR mice. Consistent with biochemical assessments, in the same brain areas we also found a robust reduction in mRNA levels of d-aspartate oxidase, encoding the enzyme responsible for d-aspartate catabolism.

CONCLUSIONS

Our results demonstrated the presence of disrupted d-aspartate metabolism in a widely used animal model of idiopathic ASD.

GENERAL SIGNIFICANCE

Overall, this work calls for a deeper investigation of D-amino acids in the etiopathology of ASD and related developmental disorders.

The histamine-4 receptor antagonist JNJ7777120 prevents immune abnormalities by inhibiting RORγt/T-bet transcription factor signaling pathways in BTBR T+ Itpr3tf/J mice exposed to gamma rays

Autism is a neurodevelopmental disorder characterized by deficits and qualitative impairments in communication and implicit skill learning. Its prevalence is higher than previous estimates, and treatments have limited efficacy and are costly. Here, we assessed the therapeutic potential of JNJ77777120 (JNJ), a histamine-4 receptor (H4R) antagonist, using BTBR T⁺ Itpr3^tf/J (BTBR) mice, a confirmed model of autism, and C57BL/6J (C57) mice, a commonly chosen reference strain. We first examined the effects of JNJ treatment on BTBR mice exposed to gamma-rays (irradiation-exposed) using a three-chambered apparatus. We further investigated the possible molecular mechanisms through which JNJ administration modulates IL-17A-, RORγT-, IL-22-, T-bet-, STAT3-, ICOS-, and Foxp3-producing CD8⁺ T cells in the spleens of irradiation-exposed BTBR mice. The effects of JNJ administration on the mRNA and protein expression of IL-17A, RORγT, IL-22, T-bet, STAT-3, pSTAT3, IL-10, and Foxp3 in brain tissue were also explored. Results showed that JNJ treatment with irradiation exposure increased social interactions in BTBR mice compared to that in irradiation-exposed BTBR mice. Additionally, JNJ-treated and irradiation-exposed BTBR mice exhibited decreases in IL-17A-, RORγT-, IL-22-, T-bet-, and STAT3-producing CD8⁺ T cells and increases in ICOS- and Foxp3-producing CD8⁺ T cells. Moreover, JNJ treatment and irradiation exposure in BTBR mice regulated the mRNA and protein expression levels of IL-17A, RORγT, IL-22, T-bet, STAT3, pSTAT-3, IL-10, and Foxp3 in the brain tissue. These results suggest that JNJ is useful for the treatment of autism, as this H4R antagonist could block inflammatory cytokine production and transcription factor signaling.

A multifaceted approach for analyzing complex phenotypic data in rodent models of autism

Autism (MIM 209850) is a multifactorial disorder with a broad clinical presentation. A number of high-confidence ASD risk genes are known; however, the contribution of non-genetic environmental factors towards ASD remains largely uncertain. Here, we present a bioinformatics resource of genetic and induced models of ASD developed using a shared annotation platform. Using this data, we depict the intricate trends in the research approaches to analyze rodent models of ASD. We identify the top 30 most frequently studied phenotypes extracted from rodent models of ASD based on 787 publications. As expected, many of these include animal model equivalents of the “core” phenotypes associated with ASD, such as impairments in social behavior and repetitive behavior, as well as several comorbid features of ASD including anxiety, seizures, and motor-control deficits. These phenotypes have also been studied in models based on a broad range of environmental inducers present in the database, of which gestational exposure to valproic acid (VPA) and maternal immune activation models comprising lipopolysaccharide (LPS) and poly I:C are the most studied. In our unique dataset of rescue models, we identify 24 pharmaceutical agents tested on established models derived from various ASD genes and CNV loci for their efficacy in mitigating symptoms relevant for ASD. As a case study, we analyze a large collection of Shank3 mouse models providing a high-resolution view of the in vivo role of this high-confidence ASD gene, which is the gateway towards understanding and dissecting the heterogeneous phenotypes seen in single-gene models of ASD. The trends described in this study could be useful for researchers to compare ASD models and to establish a complete profile for all relevant animal models in ASD research.

Helminth therapy for autism under gut-brain axis- hypothesis

Autism is a neurodevelopmental disease included within Autism Syndrome Disorder (ASD) spectrum. ASD has been linked to a series of genes that play a role in immune response function and patients with autism, commonly suffer from immune-related comorbidities. Despite the complex pathophysiology of autism, Gut-brain axis is gaining strength in the understanding of several neurological disorders. In addition, recent publications have shown the correlation between immune dysfunctions, gut microbiota and brain with the behavioral alterations and comorbid symptoms found in autism. Gut-brain axis acts as the "second brain", in a communication network established between neural, endocrine and the immunological systems. On the other hand, Hygiene Hypothesis suggests that the increase in the incidence of autoimmune diseases in the modern world can be attributed to the decrease of exposure to infectious agents, as parasitic nematodes. Helminths induce modulatory and protective effects against several inflammatory disorders, maintaining gastrointestinal homeostasis and modulating brain functions. Helminthic therapy has been previously performed in diseases such as ulcerative colitis, Crohn's disease, diabetes, multiple sclerosis, asthma, rheumatoid arthritis, and food allergies. Considering gut-brain axis, Hygiene Hypothesis, and the modulatory effects of helminths I hypothesized that a treatment with Trichuris suis soluble products represents a feasible holistic treatment for autism, and the key for the development of novel treatments. Preclinical studies are required to test this hypothesis.

Comorbid epilepsy in autism spectrum disorder: Implications of postnatal inflammation for brain excitability

OBJECTIVE

In different cohorts, 5%-30% of individuals with autism spectrum disorder (ASD) also have epilepsy. The high co-occurrence of these disorders suggests that a common mechanistic link may exist. The underlying pathophysiology of this comorbidity remains unknown. To investigate the mechanism(s) involved in the pathogenesis of ASD and epilepsy, we developed and validated a novel mouse model that concurrently exhibits hallmark features of both disorders.

METHODS

We utilized inbred BTBR T+ Itpr3tf/J (BTBR) mice that exhibit the core behavioral characteristics of ASD (ie, impaired sociability, altered vocalizations, and restricted interests). BTBR mice received a lipopolysaccharide (LPS) or sterile saline injection at postnatal day (P)7, P14, or P21. Cytokine expression was analyzed for interleukin (IL)-1β, IL-10, IL-6, and tumor necrosis factor α in brain tissue of P7 and adult BTBR mice. Adult BTBR mice were behaviorally analyzed for seizure susceptibility, sociability, communication deficits, and motor stereotypies, and monitored using chronic video-electroencephalography (EEG).

RESULTS

Adult male and female BTBR mice treated at P7-P14 with LPS were more sensitive to pentylenetetrazol-induced seizures than saline-treated controls. ASD-like behaviors and hippocampal cytokine levels were unchanged between P7 LPS-treated BTBR mice and controls. EEG recordings from the dorsal hippocampus revealed a significant increase in number and frequency of seizures over the 4-week recording period (P60-P88) in BTBR mice postnatally treated with LPS at P7. These results indicate the presence of a comorbid epileptic phenotype in BTBR mice.

SIGNIFICANCE

These findings suggest that an early postnatal immune challenge can increase brain excitability in adult BTBR mice and reveal an underlying epilepsy phenotype. This novel animal model may enable the elucidation of specific molecular alterations that are associated with the concurrent presentation of ASD and epilepsy, which could facilitate the development of targeted therapies for individuals affected by this comorbidity.

Mood Stabilizers in Children and Adolescents With Autism Spectrum Disorders

Autism spectrum disorders (ASDs) are a group of neurodevelopmental disorders including autistic disorder, Asperger syndrome, and pervasive developmental disorder not otherwise specified as to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. All these categories are grouped together in Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, classification under the category of Autism Spectrum Disorders.Behavioral disorders including irritability, attention-deficit/hyperactivity disorder (ADHD) symptoms, and aggression are additional symptoms found in up to 20% of children and adolescents with ASD and require careful evaluation for appropriate treatment. Attention-deficit/hyperactivity disorder is defined by impaired attention, hyperactivity, and impulsivity, whereas ASD is defined by social dysfunction, communicative impairment, and restricted/repetitive behaviors. They should be distinctly evaluated in children and adolescents with ASD and intellectual disability in contrast to individuals without intellectual disability, because significant differences between these conditions exist. Mood disorders are also common in ASD and should be systematically investigated in this population of children and adolescents. Approximately 50% of children and adolescents with ASD receive medication for comorbid behavioral/ADHD and mood symptoms, mostly stimulants, antiepileptics and antipsychotics. Guidelines for the evaluation and treatment including medications for ADHD-like symptoms have recently been provided and should be carefully considered. Antiepileptic drugs are commonly used in ASDs with epilepsy, because seizures are associated with ASD in 10% to 30% of young patients, and as mood stabilizers. Lithium is another option for children and adolescents with ASD who present with symptoms of a mood disorder, such as elevated moods/euphoria, mania, and paranoia, whether accompanied or not by irritability. Experimental treatments are under investigation and currently include arbaclofen, a γ-aminobutyric acid agent, and N-acetylcisteine, a glutamate agent.

Mouse Model of Chromosome 15q13.3 Microdeletion Syndrome Demonstrates Features Related to Autism Spectrum Disorder

The chromosome 15q13.3 microdeletion is a pathogenic copy number variation conferring epilepsy, intellectual disability, schizophrenia, and autism spectrum disorder (ASD). We generated mice carrying a deletion of 1.2 Mb homologous to the 15q13.3 microdeletion in human patients. Here, we report that mice with a heterozygous deletion on a C57BL/6 background (D/+ mice) demonstrated phenotypes including enlarged/heavier brains (macrocephaly) with enlarged lateral ventricles, decreased social interactions, increased repetitive grooming behavior, reduced ultrasonic vocalizations, decreased auditory-evoked gamma band EEG, and reduced event-related potentials. D/+ mice had normal body weight, activity levels, sensory gating, and cognitive abilities and no signs of epilepsy/seizures. Our results demonstrate that D/+ mice represent ASD-related phenotypes associated with 15q13.3 microdeletion syndrome. Further investigations using this chromosome-engineered mouse model may uncover the common mechanism(s) underlying ASD and other neurodevelopmental/psychiatric disorders representing the 15q13.3 microdeletion syndrome, including epilepsy, intellectual disability, and schizophrenia.

SIGNIFICANCE STATEMENT

Recently discovered pathologic copy number variations (CNVs) from patients with neurodevelopmental/psychiatric disorders show very strong penetrance and thus are excellent candidates for mouse models of disease that can mirror the human genetic conditions with high fidelity. A 15q13.3 microdeletion in humans results in a range of neurodevelopmental/psychiatric disorders, including epilepsy, intellectual disability, schizophrenia, and autism spectrum disorder (ASD). The disorders conferred by a 15q13.3 microdeletion also have overlapping genetic architectures and comorbidity in other patient populations such as those with epilepsy and schizophrenia/psychosis, as well as schizophrenia and ASD. We generated mice carrying a deletion of 1.2 Mb homologous to the 15q13.3 microdeletion in human patients, which allowed us to investigate the potential causes of neurodevelopmental/psychiatric disorders associated with the CNV.

Lack of Association Between Polymorphisms in Dopa Decarboxylase and Dopamine Receptor-1 Genes With Childhood Autism in Chinese Han Population

Genetic factors play an important role in childhood autism. This study is to determine the association of single-nucleotide polymorphisms in dopa decarboxylase (DDC) and dopamine receptor-1 (DRD1) genes with childhood autism, in a Chinese Han population. A total of 211 autistic children and 250 age- and gender-matched healthy controls were recruited. The severity of disease was determined by Children Autism Rating Scale scores. TaqMan Probe by real-time polymerase chain reaction was used to determine genotypes and allele frequencies of single-nucleotide polymorphism rs6592961 in DDC and rs251937 in DRD1. Case-control and case-only studies were respectively performed, to determine the contribution of both single-nucleotide polymorphisms to the predisposition of disease and its severity. Our results showed that there was no significant association of the genotypes and allele frequencies of both single-nucleotide polymorphisms concerning childhood autism and its severity. More studies with larger samples are needed to corroborate their predicting roles.

Autism-Like Behavior in BTBR Mice Is Improved by Electroconvulsive Therapy

Autism is a developmental disorder characterized by impairments in social and communication abilities, as well as by restricted and repetitive behaviors. Incidence of autism is higher than earlier estimates, and treatments have limited efficacy and are costly. Limited clinical and experimental evidence suggest that patients with autism may benefit from electroconvulsive therapy (ECT). We examined the therapeutic potential of ECT in BTBR T+ tf/j mice, which represent a validated model of autism. A series of 13 electroconvulsive shocks (ECS) delivered twice a day over 7 days reversed core autism-like behavioral abnormalities-impaired sociability, social novelty, and repetitive behavior-when the animals were tested 24 h after the last ECS. The effect lasted up to 2 weeks after ECT. Neither single ECS nor a series of 6 ECS modified animals' behavior. Chronic infusion into the lateral brain ventricle of a preferential oxytocin receptor blocker (2S)-2-Amino-N-[(1S,2S,4R)-7,7-dimethyl-1-[[[4-(2-methylphenyl)-1-piperazinyl]sulfonyl]methyl]bicyclo[2.2.1]hept-2-yl]-4-(methylsulfonyl)butanamide hydrochloride abolished ECT-induced improvement of sociability and mitigated improvement of social novelty but did not affect ECT-induced reversal of repetitive behavior. These proof-of-principle experiments suggest that ECT may, indeed, be useful in the treatment of autism, and that its therapeutic effects may be mediated, in part, by central oxytocin signaling.

Peroxisome proliferator-activated receptor alpha plays a crucial role in behavioral repetition and cognitive flexibility in mice

Background/objectives

Nuclear peroxisome proliferator activated receptor-α (PPAR-α) plays a fundamental role in the regulation of lipid homeostasis and is the target of medications used to treat dyslipidemia. However, little is known about the role of PPAR-α in mouse behavior.

Methods

To investigate the function of Ppar-α in cognitive functions, a behavioral phenotype analysis of mice with a targeted genetic disruption of Ppar-α was performed in combination with neuroanatomical, biochemical and pharmacological manipulations. The therapeutic exploitability of PPAR-α was probed in mice using a pharmacological model of psychosis and a genetic model (BTBR T + tf/J) exhibiting a high rate of repetitive behavior.

Results

An unexpected role for brain Ppar-α in the regulation of cognitive behavior in mice was revealed. Specifically, we observed that Ppar-α genetic perturbation promotes rewiring of cortical and hippocampal regions and a behavioral phenotype of cognitive inflexibility, perseveration and blunted responses to psychomimetic drugs. Furthermore, we demonstrate that the antipsychotic and autism spectrum disorder (ASD) medication risperidone ameliorates the behavioral profile of Ppar-α deficient mice. Importantly, we reveal that pharmacological PPAR-α agonist treatment in mice improves behavior in a pharmacological model of ketamine-induced behavioral dysinhibition and repetitive behavior in BTBR T + tf/J mice.

Conclusion

Our data indicate that Ppar-α is required for normal cognitive function and that pharmacological stimulation of PPAR-α improves cognitive function in pharmacological and genetic models of impaired cognitive function in mice. These results thereby reveal an unforeseen therapeutic application for a class of drugs currently in human use.

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The lipid nuclear receptor PPAR-α is required for normal cognitive function in mice.

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Genetic ablation of Ppar-α promotes repetitive behavior and cognitive inflexibility in mice.

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Pharmacological stimulation of PPAR-α improves behaviors in models of impaired cognition and enhanced repetitive behavior.

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Our findings suggest Ppar-α as a possible point of commonality between behavioral and metabolic dysfunctions.

Clinical potential, safety, and tolerability of arbaclofen in the treatment of autism spectrum disorder

Autism spectrum disorder (ASD) is a behaviorally defined disorder which has increased in prevalence over the last two decades. Despite decades of research, no effective treatment is currently available. Animal models, as well as other lines of evidence, point to abnormalities in the balance of cortical excitation to inhibition in individuals with ASD, with this imbalance resulting in an overall increase in cortical excitation. To reduce cortical excitatory glutamate pathways, arbaclofen, a selective agonist of the gamma aminobutyric acid receptor type B, has been developed. This article reviews the evidence for this treatment for ASD using a systematic review methodology. Overall, a systematic search of the literature revealed 148 relevant references with the majority of these being review papers or news items that mentioned the potential promise of arbaclofen. Five original studies were identified, four of which used STX209, a form of arbaclofen developed by Seaside Therapeutics, Inc., and one which used R-baclofen. In an animal model, treatment of Fragile X, a genetic disease with ASD features, demonstrated a reversal of behavioral, neurological, and neuropathological features associated with the disease. One double-blind, placebo-controlled study treated children and adults with Fragile X. Results from this study were promising, with signs of improvement in social function, especially in the most severely socially impaired. Two studies, one open-label and one double-blind, placebo-controlled, were conducted in children, adolescents, and young adults with ASD. These studies suggested some improvements in socialization, although the effects were limited and may have been driven by individuals with ASD that were higher-functioning. These studies and others that have used arbaclofen for the treatment of gastroesophageal reflux suggest that arbaclofen is safe and well-tolerated. Clearly, further clinical studies are needed in order to refine the symptoms and characteristics of children with ASD that are best treated with arbaclofen.

Mesenchymal stem cells in treating autism: Novel insights

Autism spectrum disorders (ASDs) are complex neurodevelopmental disorders characterized by dysfunctions in social interactions, abnormal to absent verbal communication, restricted interests, and repetitive stereotypic verbal and non-verbal behaviors, influencing the ability to relate to and communicate. The core symptoms of ASDs concern the cognitive, emotional, and neurobehavioural domains. The prevalence of autism appears to be increasing at an alarming rate, yet there is a lack of effective and definitive pharmacological options. This has created an increased sense of urgency, and the need to identify novel therapies. Given the growing awareness of immune dysregulation in a significant portion of the autistic population, cell therapies have been proposed and applied to ASDs. In particular, mesenchymal stem cells (MSCs) possess the immunological properties which make them promising candidates in regenerative medicine. MSC therapy may be applicable to several diseases associated with inflammation and tissue damage, where subsequent regeneration and repair is necessary. MSCs could exert a positive effect in ASDs through the following mechanisms: stimulation of repair in the damaged tissue, e.g., inflammatory bowel disease; synthesizing and releasing anti-inflammatory cytokines and survival-promoting growth factors; integrating into existing neural and synaptic network, and restoring plasticity. The paracrine mechanisms of MSCs show interesting potential in ASD treatment. Promising and impressive results have been reported from the few clinical studies published to date, although the exact mechanisms of action of MSCs in ASDs to restore functions are still largely unknown. The potential role of MSCs in mediating ASD recovery is discussed in light of the newest findings from recent clinical studies.

Decoding the contribution of dopaminergic genes and pathways to autism spectrum disorder (ASD)

Autism spectrum disorder (ASD) is a debilitating brain illness causing social deficits, delayed development and repetitive behaviors. ASD is a heritable neurodevelopmental disorder with poorly understood and complex etiology. The central dopaminergic system is strongly implicated in ASD pathogenesis. Genes encoding various elements of this system (including dopamine receptors, the dopamine transporter or enzymes of synthesis and catabolism) have been linked to ASD. Here, we comprehensively evaluate known molecular interactors of dopaminergic genes, and identify their potential molecular partners within up/down-steam signaling pathways associated with dopamine. These in silico analyses allowed us to construct a map of molecular pathways, regulated by dopamine and involved in ASD. Clustering these pathways reveals groups of genes associated with dopamine metabolism, encoding proteins that control dopamine neurotransmission, cytoskeletal processes, synaptic release, Ca(2+) signaling, as well as the adenosine, glutamatergic and gamma-aminobutyric systems. Overall, our analyses emphasize the important role of the dopaminergic system in ASD, and implicate several cellular signaling processes in its pathogenesis.

Pharmacotherapy for the core symptoms in autistic disorder: current status of the research

The current review covers extant literature on pharmacotherapy for core symptoms of autism. The core symptoms of autism include impairments in social interaction and communication, as well as the presence of restricted and repetitive behaviors. There are no known efficacious treatments for the core social symptoms, although effects on repetitive behaviors are indicated with some data. While studies of fenfluramine, secretin, opiates, and mood stabilizers generally find no effect, mixed results suggest more research is needed on antidepressants and atypical antipsychotics. Newer lines of research, including cholinergic and glutamatergic agents and oxytocin, will be of considerable interest in the future. However, research on the treatment of core symptoms is plagued by limitations in study design, statistical power, and other issues inherent to the study of treatments for autism (e.g., heterogeneity of the disorder) that continue to prevent the elucidation of efficacious treatments.

A review of traditional and novel treatments for seizures in autism spectrum disorder: findings from a systematic review and expert panel

Despite the fact that seizures are commonly associated with autism spectrum disorder (ASD), the effectiveness of treatments for seizures has not been well studied in individuals with ASD. This manuscript reviews both traditional and novel treatments for seizures associated with ASD. Studies were selected by systematically searching major electronic databases and by a panel of experts that treat ASD individuals. Only a few anti-epileptic drugs (AEDs) have undergone carefully controlled trials in ASD, but these trials examined outcomes other than seizures. Several lines of evidence point to valproate, lamotrigine, and levetiracetam as the most effective and tolerable AEDs for individuals with ASD. Limited evidence supports the use of traditional non-AED treatments, such as the ketogenic and modified Atkins diet, multiple subpial transections, immunomodulation, and neurofeedback treatments. Although specific treatments may be more appropriate for specific genetic and metabolic syndromes associated with ASD and seizures, there are few studies which have documented the effectiveness of treatments for seizures for specific syndromes. Limited evidence supports l-carnitine, multivitamins, and N-acetyl-l-cysteine in mitochondrial disease and dysfunction, folinic acid in cerebral folate abnormalities and early treatment with vigabatrin in tuberous sclerosis complex. Finally, there is limited evidence for a number of novel treatments, particularly magnesium with pyridoxine, omega-3 fatty acids, the gluten-free casein-free diet, and low-frequency repetitive transcranial magnetic simulation. Zinc and l-carnosine are potential novel treatments supported by basic research but not clinical studies. This review demonstrates the wide variety of treatments used to treat seizures in individuals with ASD as well as the striking lack of clinical trials performed to support the use of these treatments. Additional studies concerning these treatments for controlling seizures in individuals with ASD are warranted.

Therapeutic role of hematopoietic stem cells in autism spectrum disorder-related inflammation

Autism and autism spectrum disorders (ASDs) are heterogeneous, severe neuro-developmental disorders with core symptoms of dysfunctions in social interactions and communication skills, restricted interests, repetitive – stereotypic verbal and non-verbal behaviors. Biomolecular evidence points to complex gene-environmental interactions in ASDs. Several biochemical processes are associated with ASDs: oxidative stress (including endoplasmic reticulum stress), decreased methylation capacity, limited production of glutathione; mitochondrial dysfunction, intestinal dysbiosis, increased toxic metal burden, and various immune abnormalities. The known immunological disorders include: T-lymphocyte populations and function, gene expression changes in monocytes, several autoimmune-related findings, high levels of N-acetylgalactosaminidase (which precludes macrophage activation), and primary immune deficiencies. These immunological observations may result in minicolumn structural changes in the brain, as well as, abnormal immune mediation of synaptic functions. Equally, these immune dysregulations serve as the rationale for immune-directed interventions such as hematopoietic stem cells (HSCs), which are pivotal in controlling chronic inflammation and in the restoration of immunological balance. These properties make them intriguing potential agents for ASD treatments. This prospective review will focus on the current state-of-the-art knowledge and challenges intrinsic in the application of HSCs for ASD-related immunological disorders.

Ketogenic diet improves core symptoms of autism in BTBR mice

Autism spectrum disorders share three core symptoms: impaired sociability, repetitive behaviors and communication deficits. Incidence is rising, and current treatments are inadequate. Seizures are a common comorbidity, and since the 1920's a high-fat, low-carbohydrate ketogenic diet has been used to treat epilepsy. Evidence suggests the ketogenic diet and analogous metabolic approaches may benefit diverse neurological disorders. Here we show that a ketogenic diet improves autistic behaviors in the BTBR mouse. Juvenile BTBR mice were fed standard or ketogenic diet for three weeks and tested for sociability, self-directed repetitive behavior, and communication. In separate experiments, spontaneous intrahippocampal EEGs and tests of seizure susceptibility (6 Hz corneal stimulation, flurothyl, SKF83822, pentylenetetrazole) were compared between BTBR and control (C57Bl/6) mice. Ketogenic diet-fed BTBR mice showed increased sociability in a three-chamber test, decreased self-directed repetitive behavior, and improved social communication of a food preference. Although seizures are a common comorbidity with autism, BTBR mice fed a standard diet exhibit neither spontaneous seizures nor abnormal EEG, and have increased seizure susceptibility in just one of four tests. Thus, behavioral improvements are dissociable from any antiseizure effect. Our results suggest that a ketogenic diet improves multiple autistic behaviors in the BTBR mouse model. Therefore, ketogenic diets or analogous metabolic strategies may offer novel opportunities to improve core behavioral symptoms of autism spectrum disorders.

Possible use of Trichuris suis ova in autism spectrum disorders therapy

Autism and autism spectrum disorders (ASDs) are heterogeneous, severe neurodevelopmental pathologies. The main core symptoms are: dysfunctions in social interactions and communication skills, restricted interests, repetitive and stereotypic verbal and non-verbal behaviors. Several biochemical processes are associated with ASDs: oxidative stress; endoplasmic reticulum stress; decreased methylation capacity; limited production of glutathione; mitochondrial dysfunction; intestinal dysbiosis; increased toxic metal burden; immune dysregulation. Current available treatments for ASDs can be divided into behavioral, nutritional and medical approaches, although no defined standard approach exists. Current drugs fail to benefit the ASD core symptoms and can have marked adverse effects, are mainly palliative and only sometimes efficacy in attenuating specific autistic behaviors. Helminthic therapy shows potential for application as anti-inflammatory agent. Several human diseases can be treated by helminths (i.e. inflammatory bowel disease, asthma, multiple sclerosis and autoimmune diabetes). Trichuris suis ova (TSO) show strong immunomodulatory properties. Authors hypothesize that TSO could be useful in addressing ASD immune dysregulations. TSO could be a novel therapeutic option for ASD management.

AMPAKINE enhancement of social interaction in the BTBR mouse model of autism

Autism is a neurodevelopmental disorder in which the first diagnostic symptom is unusual reciprocal social interactions. Approximately half of the children diagnosed with an autism spectrum disorder also have intellectual impairments. General cognitive abilities may be fundamental to many aspects of social cognition. Cognitive enhancers could conceivably be of significant benefit to children and adults with autism. AMPAKINE compounds are a novel class of pharmacological agents that act as positive modulators of AMPA receptors to enhance excitatory glutamatergic neurotransmission. This class of compounds was reported to improve learning and memory in several rodent and non-human primate tasks, and to normalize respiratory abnormalities in a mouse model of Rett syndrome. Here we evaluate the actions of AMPA compounds in adult male and female BTBR mice, a well characterized mouse model of autism. Acute treatment with CX1837 and CX1739 reversed the deficit in sociability in BTBR mice on the most sensitive parameter, time spent sniffing a novel mouse as compared to time spent sniffing a novel object. The less sensitive parameter, time in the chamber containing the novel mouse versus time in the chamber containing the novel object, was not rescued by CX1837 or CX1739 treatment. Preliminary data with CX546, in which β-cyclodextrin was the vehicle, revealed behavioral effects of the acute intraperitoneal and oral administration of vehicle alone. To circumvent the artifacts introduced by the vehicle administration, we employed a novel treatment regimen using pellets of peanut butter for drug delivery. Absence of vehicle treatment effects when CX1837 and CX1739 were given in the peanut butter pellets, to multiple cohorts of BTBR and B6 control mice, confirmed that the pharmacologically-induced improvements in sociability in BTBR were not confounded by the administration procedures. The highest dose of CX1837 improved the cognitive deficit in novel object recognition in BTBR. No drug effects were detected on the high levels of repetitive self-grooming in BTBR. In open field tests, CX1837 and CX1739 did not induce hyperactivity or sedation in either strain. It is interesting to speculate that the ability of CX1837 and CX1739 to restore aspects of sociability in BTBR mice could utilize synaptic mechanisms regulating social cognition, suggesting a potential pharmacological target for interventions to treat symptoms of autism. This article is part of a Special Issue entitled 'Cognitive Enhancers'.