Pros and cons of narrow- versus wide-compartment rotarod apparatus: An experimental study in mice.

The rotarod test, a sensorimotor assessment that allows for quantitative evaluation of motor coordination in rodents, has extensive application in many research fields. The test results exhibit extreme between-study variability, sometimes making it challenging to conclude the validity of certain disease models and related therapeutic effects. Although the variation in test paradigms may account for this disparity, some features of rotarod apparatus including rod diameter make differences. However, it is unknown whether the width of animal compartment has a role in rotarod performance. Here we comprehensively evaluated the active rotarod performance and adverse incidents in multiple strains of mice on an 11-cm- or a 5-cm-wide compartment apparatus. We found that mouse behaviors on these apparatuses were surprisingly different. It took a markedly longer time to train mice on the narrow- than wide-compartment rotarod. Further, non-transgenic B6129S and tau knockout mice aged 11 months and beyond showed different levels of improvement based on the compartment width. These mice had no overt improvements on accelerating rotarod over 4-5 training sessions on the narrow compartment, contrary to marked progress on the wide counterpart. The incidents of mice passively somersaulting round and fragmented running occurred significantly more on the wide than narrow compartment during accelerating rotarod sessions. Mice fell off rod more frequently on narrow than wide compartments upon attempt to turn around and when moving backward on rod. The pros and cons of narrow versus wide compartments are informative as to how to choose a rotarod apparatus that best fits the animal models used.

Efficient Delivery of FMR1 across the Blood Brain Barrier Using AAVphp Construct in Adult FMR1 KO Mice Suggests the Feasibility of Gene Therapy for Fragile X Syndrome.

Background Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability and autism. Gene therapy may offer an efficient method to ameliorate the symptoms of this disorder. Methods An AAVphp.eb-hSyn-mFMR1IOS7 vector and an empty control were injected into the tail vein of adult Fmr1 knockout (KO) mice and wildtype (WT) controls. The KO mice were injected with 2 × 1013 vg/kg of the construct. The control KO and WT mice were injected with an empty vector. Four weeks following treatment, the animals underwent a battery of tests: open field, marble burying, rotarod, and fear conditioning. The mouse brains were studied for levels of the Fmr1 product FMRP. Results: No significant levels of FMRP were found outside the CNS in the treated animals. The gene delivery was highly efficient, and it exceeded the control FMRP levels in all tested brain regions. There was also improved performance in the rotarod test and partial improvements in the other tests in the treated KO animals. Conclusion: These experiments demonstrate efficient, brain-specific delivery of Fmr1 via peripheral administration in adult mice. The gene delivery led to partial alleviation of the Fmr1 KO phenotypical behaviors. FMRP oversupply may explain why not all behaviors were significantly affected. Since AAV.php vectors are less efficient in humans than in the mice used in the current experiment, studies to determine the optimal dose using human-suitable vectors will be necessary to further demonstrate feasibility.

Does the stranger mouse strain matter to female BTBR mice?

Autism spectrum disorder (ASD) is characterized by deficits in social communication and repetitive behaviors/restricted interests. One mouse model of ASD is the BTBR T+Itprtf/J (BTBR) mice which display low levels of social behavior in several tests. The social approach test is used to examine the preference for social interaction between a stranger mouse or a novel object. While female BTBR mice have been used in the social approach test, no one has examined the degree to which the strain of the stranger mouse will affect social behavior. The current experiment tested female BTBR subject mice in the social approach test with stranger mice from different strains including the BTBR, 129S1/SvImJ (129), and C57BL/6J (B6) mice, of which the B6 mice are most social. The results show that female BTBR mice overall spent significantly more time in the stranger mouse chamber. However, further analysis revealed that the subject mice spent significantly more time in the stranger mouse chamber when the stranger was from the B6 strain, but not the BTBR or 129 strains. The BTBR female mice also sniffed the B6 and 129 stranger mice more than the novel object. This suggests that BTBR females are more social with mice that display high levels of social behavior, but less so with less social mice.

Pharmacological inhibition of the primary endocannabinoid producing enzyme, DGL-α, induces autism spectrum disorder-like and co-morbid phenotypes in adult C57BL/J mice.

Accumulating evidence links dysfunction in the endocannabinoid system (ECS) with the pathology of neurodevelopmental disorders, particularly autism spectrum disorder (ASD). Variants in ECS genes CNR1 and DAGLA are associated with neurological phenotypes in humans. The endocannabinoids (eCBs), 2-AG and AEA, which act at the primary cannabinoid receptor (CB1), mediate behaviors relevant to neurodevelopmental disorders. The overlap between these eCBs is poorly understood. Most ECS studies have focused on stress responses, anxiety, and epilepsy, however, its role in social behavior and communication has only recently come under investigation. This represents a critical gap in our understanding of the ECS and its relationship to ASD. Furthermore, the increasing prevalence of ASD and a lack of therapeutics emphasize a crucial need for novel therapeutic targets. To this aim, we used an inhibitor of the eCB producing enzyme DGL-α, DO34, and the CB1 inverse agonist, rimonabant, to evaluate the role of the primary eCB, 2-AG, in ASD. Adult male C57BL/6J mice were used in a series of behavioral paradigms which assessed social behavior, social communication, repetitive behaviors, anxiety and locomotor activity. DO34 and rimonabant increased anxiety-like behavior, while only DO34 induced hyperactivity, social deficits, and repetitive self-grooming behavior. These data indicate that reduced 2-AG bioavailability, or CB1 inhibition, each induce unique respective behavioral phenotypes relevant to neurodevelopmental disorders, particularly ASD. This suggests fundamental differences in CB1 signaling via 2-AG and the CB1 receptor itself, particularly for social behaviors, and that 2-AG signaling may represent a target for the development of novel therapeutics. LAY SUMMARY: Endocannabinoids play a critical role in the developing nervous system. Alterations in the endocannabinoid system are linked to neurodevelopmental disorders. Studies suggest these variants may play a critical role in the core symptoms of autism spectrum disorder. In this study, pharmacological inhibition of the primary endocannabinoid producing enzyme, DGL-α, induced a constellation of deficits in behavioral domains associated with autism.

Pharmacological inhibition of BKCa channels induces a specific social deficit in adult C57BL6/J mice.

Genetic variants in large conductance voltage and calcium sensitive potassium (BKCa) channels have associations with neurodevelopmental disorders such as autism spectrum disorder, fragile X syndrome, and intellectual disability. In the case of fragile X syndrome, early preclinical studies suggest that BKCa channels may be a promising treatment target for neurodevelopmental disorders. While BKCa channel dysfunction has been investigated within the context of fragile X syndrome, it is unknown whether interference with BKCa channel function is inductive for deficits in behavioral domains relevant to neurodevelopmental disorders. This represents a critical gap in our knowledge regarding the relationship between BKCa dysfunction and neurodevelopmental disorders. To explore this concept, we used the BKCa channel antagonist paxilline to evaluate the role of BKCa channel function in phenotypes of neurodevelopmental disorders. Here we used adult male C57BL/6J mice and a series of behavioral paradigms which assessed anxiety-like behavior, locomotor activity, social behavior, and repetitive self-grooming. We found that acute inhibition with paxilline induced a specific social deficit, but not anxiety-like behavior, or hyperactivity. These findings demonstrate proof-of-concept regarding a relationship between BKCa channel impairment and social behavior. Although this is a limited characterization of the BKCa channel in autistic-like behaviors, it provides evidence for this link. Future studies which examine the effective dose range of paxilline and exhaustive assays of behavior relevant to neurodevelopmental disorders will be needed to delineate the parametric space of the paxilline effect, particularly during critical periods of development, and its potential for therapeutic use. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Taurine Partially Improves Abnormal Anxiety in Taurine-Deficient Mice.

Taurine is abundant in various tissues including the brain, muscle, heart, spleen, liver and kidney with various physiological functions. Since taurine is produced by cysteine sulfinic acid decarboxylase (CSAD) in the liver and kidney, taurine-deficient mice without CSAD have been investigated for abnormal physiological functions such as retinal development, immune, pancreatic and liver function. In this study, the behavioral effects and abnormal brain development caused by low taurine in the developing brain were examined. In neonatal brains of homozygous CSAD knockout mice (HO), taurine was reduced by 85%, compared to wild-type mice (WT). Taurine was reduced by 35% in the brains of 2 month-old HO, compared to WT. Anxiety, motor coordination and autistic-like behaviors were evaluated at 2 months of age using five behavioral tests: elevated plus maze, open field, social approach, marble burying and accelerating rotarod. Mice were tested from 3 groups including WT, HO and HO with oral treatment of 0.2% taurine in the drinking water (HOT). HOT were born from HO dams treated with taurine from before pregnancy and were continuously treated with taurine in the drinking water after weaning. The taurine levels in the brain and plasma of HOT were restored to WT at 2 months of age. Taurine-deficiency did not lead to changes in autistic-like behaviors as the HO were not significantly different from WT in marble burying and social approach. However, taurine-deficiency increased anxiety-like behavior in HO in the elevated plus maze and open field, compared to WT. Taurine treatment significantly restored the HOT to WT levels of anxiety-like behavior in the elevated plus maze. However, changes in exploratory activity in the open field were not improved with taurine treatment. There was a slight difference in motor ability as the WT mice stayed on the accelerating rotarod longer that the HO and HOT, but the difference was significant in the HOT during the first trial only, compared to WT.These data support hypothesis that taurine is essential for the emotional development of the brain. First, taurine is remarkably low in the neonatal brain of HO, compared to the adult brain of HO. Second, taurine treatment in HO partially improves anxiety-like behavior to WT.

Inbred strain preference in the BTBR T+ Itpr3tf /J mouse model of autism spectrum disorder: Does the stranger mouse matter in social approach?

BTBR T+ Itpr3tf /J (BTBR) mice have been used as a model of autism spectrum disorder (ASD) due to their low levels of sociability and high levels of repetitive grooming. These experiments explored social behavior in the BTBR and C57BL/6J mice using variations of the three-chambered social approach test. In the first test, the subject mice had a choice between a stranger mouse of the same strain or from a strain with a different level of sociability. The BTBR male mice demonstrated a strong preference for the more social C57BL/6J stranger mouse, as did the C57BL/6J male mice, although more moderately with sniff time only. The C57BL/6J female mice showed a moderate preference, sniff time only, for the BTBR stranger mouse, whereas the BTBR female mice did not show a preference. The second experiment examined whether the subject mouse preferred a stranger mouse or bedding from the stranger mouse home cage. Male BTBR mice always preferred bedding, whereas the C57BL/6J male mice did not show a preference. Both BTBR and C57BL/6J female mice preferred bedding when the stranger mouse was a different strain but not when the stranger mouse was the same strain. Therefore, the stranger mouse strain seems to influence the preference of the female mice more than the male mice. The mice preferred spending time in the chamber with the social smell but not the actual stranger mouse although not always significantly. This suggests that contact with a stranger mouse is more stressful or anxiety provoking than the smell. Autism Res 2019, 12: 1184-1191. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: BTBR T+ Itpr3tf /J (BTBR) mice have been used as a model of autism spectrum disorder (ASD) due to their low levels of sociability and high levels of repetitive grooming. These experiments explored social behavior in the BTBR and C57BL/6J mice using variations of the three-chambered social approach test. These experiments examined how the sociability level of the stranger mouse affected the subject mouse's preference and if social odor was preferable to a social situation in the BTBR mice. The BTBR male mice demonstrated a strong preference for the more social C57BL/6J stranger mouse, as did the C57BL/6J male mice. The C57BL/6J female mice showed a moderate preference for the BTBR stranger mouse, whereas the BTBR female mice did not show a preference for either stranger mouse. The second modification let the subject mouse have a choice between a stranger mouse or bedding. Male BTBR mice preferred bedding, regardless of the strain of the stranger mouse, whereas the C57BL/6J male mice did not show a preference. Both BTBR and C57BL/6J female mice preferred bedding when the stranger mouse was a different strain but showed no preference when the stranger mouse was from the same strain. The stranger mouse strain seems to influence the female mice more. Male BTBR mice preferred spending time in the chamber with the social smell but not the actual mouse, suggesting that actual contact with a stranger mouse is more stressful or anxiety provoking.

Do animal models hold value in Autism spectrum disorder (ASD) drug discovery?

Introduction: Autism spectrum disorder (ASD) defines impairments in a broad range of behaviors in two domains, social communication and repetitive behaviors and/or restricted interests. Drug discovery is ongoing for ASD, but no drugs have been approved for the core behaviors. Animal models are invaluable for drug discovery, but are limited by the face, construct, and predictive validity for ASD. The genetic construct validity of animal models has provided potential targets including biological events early in development which are indeed challenging to treat pharmacologically. Areas covered: The focus of this review is on the current models for ASD being used to test potential therapeutics. Drugs reviewed include sulforaphane, propranolol, oxytocin, vasopressin antagonists, arbaclofen, and bumetanide, that have been evaluated on behaviors with face validity for both the core behaviors of ASD, social and repetitive behaviors, and the modifying behaviors including learning and memory. Expert opinion: Animal models for the core symptoms of ASD have suffered from the same problems hampering research in humans, including lack of a biomarker, heterogeneity of symptom severity, and appropriate endpoints for evaluation. Despite this, the data from animal models has allowed several drugs to move on to clinical testing.

Animal models for autism in 2017 and the consequential implications to drug discovery.

INTRODUCTION: Autism spectrum disorder (ASD) is characterized by deficits in social communication and restricted interests/repetitive behaviors, for which there are currently no approved drug treatments. The core symptoms of ASD vary widely in severity and are often accompanied by other neuropsychiatric disorders. Drug discovery has been challenging because of the lack of understanding of the underlying pathophysiology of ASD as well as the heterogeneity of symptoms and symptom severity. Areas covered: In this review, the author discusses animal models of ASD used as targets for drug discovery, focusing primarily on non-syndromic models, primarily rodents. They highlight the wide range of drug targets examined in animal models. While very little of this work has resulted in drug therapy for the behavioral symptoms of ASD yet, it has increased our knowledge of the biology of ASD that is critical for driving drug discovery and has already provided many new drug targets for investigation. Expert opinion: The information gathered from the animal models of ASD is increasing our understanding of the underlying pathophysiology for ASD and is leading to better therapeutic targets. However, the issue of small sample size, heterogeneity within clinical samples, and a lack of replicable outcome measures must be addressed to move forward.

Microarray analysis reveals higher gestational folic Acid alters expression of genes in the cerebellum of mice offspring-a pilot study.

Folate is a water-soluble vitamin that is critical for nucleotide synthesis and can modulate methylation of DNA by altering one-carbon metabolism. Previous studies have shown that folate status during pregnancy is associated with various congenital defects including the risk of aberrant neural tube closure. Maternal exposure to a methyl supplemented diet also can alter DNA methylation and gene expression, which may influence the phenotype of offspring. We investigated if higher gestational folic acid (FA) in the diet dysregulates the expression of genes in the cerebellum of offspring in C57BL/6 J mice. One week before gestation and throughout the pregnancy, groups of dams were supplemented with FA either at 2 mg/kg or 20 mg/kg of diet. Microarray analysis was used to investigate the genome wide gene expression profile in the cerebellum from day old pups. Our results revealed that exposure to the higher dose FA diet during gestation dysregulated expression of several genes in the cerebellum of both male and female pups. Several transcription factors, imprinted genes, neuro-developmental genes and genes associated with autism spectrum disorder exhibited altered expression levels. These findings suggest that higher gestational FA potentially dysregulates gene expression in the offspring brain and such changes may adversely alter fetal programming and overall brain development.

Making progress in autism drug discovery.

Currently, there are still just two medications approved by the U.S. FDA to treat the irritability that is often found in children with autism spectrum disorder (ASD). Furthermore, there are no drugs approved that treat the core symptoms of ASD. And while many drugs have had good outcomes in preclinical animal models, they have been met with very little success in human clinical trials. There are several factors likely contributing to this problem starting with the heterogeneity within the ASD phenotype. It is therefore important that researchers develop their knowledge about the neurobiological basis of ASD as well as possible subgroups within the disorder, based on either specific behavioral profiles or biological pathways. Furthermore, the development of valid biological markers will allow researchers to use more than parent or teacher reports to determine if a treatment is effective. This author believes that there a good chance of finding effective pharmacological treatments for the core symptoms of ASD with this increased knowledge of the biology and etiology.

Increasing maternal or post-weaning folic acid alters gene expression and moderately changes behavior in the offspring.

BACKGROUND: Studies have indicated that altered maternal micronutrients and vitamins influence the development of newborns and altered nutrient exposure throughout the lifetime may have potential health effects and increased susceptibility to chronic diseases. In recent years, folic acid (FA) exposure has significantly increased as a result of mandatory FA fortification and supplementation during pregnancy. Since FA modulates DNA methylation and affects gene expression, we investigated whether the amount of FA ingested during gestation alters gene expression in the newborn cerebral hemisphere, and if the increased exposure to FA during gestation and throughout the lifetime alters behavior in C57BL/6J mice. METHODS: Dams were fed FA either at 0.4 mg or 4 mg/kg diet throughout the pregnancy and the resulting pups were maintained on the diet throughout experimentation. Newborn pups brain cerebral hemispheres were used for microarray analysis. To confirm alteration of several genes, quantitative RT-PCR (qRT-PCR) and Western blot analyses were performed. In addition, various behavior assessments were conducted on neonatal and adult offspring. RESULTS: Results from microarray analysis suggest that the higher dose of FA supplementation during gestation alters the expression of a number of genes in the newborns' cerebral hemispheres, including many involved in development. QRT-PCR confirmed alterations of nine genes including down-regulation of Cpn2, Htr4, Zfp353, Vgll2 and up-regulation of Xist, Nkx6-3, Leprel1, Nfix, Slc17a7. The alterations in the expression of Slc17a7 and Vgll2 were confirmed at the protein level. Pups exposed to the higher dose of FA exhibited increased ultrasonic vocalizations, greater anxiety-like behavior and hyperactivity. These findings suggest that although FA plays a significant role in mammalian cellular machinery, there may be a loss of benefit from higher amounts of FA. Unregulated high FA supplementation during pregnancy and throughout the life course may have lasting effects, with alterations in brain development resulting in changes in behavior.

Mice over-expressing BDNF in forebrain neurons develop an altered behavioral phenotype with age.

Evidence from clinical studies suggests that abnormal activity of brain derived neurotrophic factor (BDNF) contributes to the pathogenesis of autism spectrum disorders (ASDs). A genetically modified line of mice over-expressing a BDNF transgene in forebrain neurons was used to investigate if this mutation leads to changes in behavior consistent with ASD. The mice used in these experiments were behaviorally tested past 5 months of age when spontaneous seizures were evident. These seizures were not observed in age-matched wildtype (WT) mice or younger mice from this transgenic line. The BDNF mice in these experiments weighed less than their WT littermates. The BDNF transgenic (BDNF-tg) mice demonstrated similar levels of sociability in the social approach test. Conversely, the BDNF-tg mice demonstrated less obsessive compulsive-like behavior in the marble burying test, less anxiety-like behavior in the elevated plus maze test, and less depressive-like behavior in the forced swim test. Changes in behavior were found in these older mice that have not been observed in younger mice from this transgenic line, which may be due to the development of seizures as the mice age. These mice do not have an ASD phenotype but may be useful to study adult onset epilepsy.

Single-base resolution of mouse offspring brain methylome reveals epigenome modifications caused by gestational folic acid.

BACKGROUND: Epigenetic modifications, such as cytosine methylation in CpG-rich regions, regulate multiple functions in mammalian development. Maternal nutrients affecting one-carbon metabolism during gestation can exert long-term effects on the health of the progeny. Using C57BL/6 J mice, we investigated whether the amount of ingested maternal folic acid (FA) during gestation impacted DNA methylation in the offspring's cerebral hemispheres. Reduced representation bisulfite sequencing at single-base resolution was performed to analyze genome-wide DNA methylation profiles. RESULTS: We identified widespread differences in the methylation patterns of CpG and non-CpG sites of key developmental genes, including imprinted and candidate autism susceptibility genes (P <0.05). Such differential methylation of the CpG and non-CpG sites may use different mechanisms to alter gene expressions. Quantitative real time reverse transcription-polymerase chain reaction confirmed altered expression of several genes. CONCLUSIONS: These finding demonstrate that high maternal FA during gestation induces substantial alteration in methylation pattern and gene expression of several genes in the cerebral hemispheres of the offspring, and such changes may influence the overall development. Our findings provide a foundation for future studies to explore the influence of gestational FA on genetic/epigenetic susceptibility to altered development and disease in offspring.

Water T-maze: a useful assay for determination of repetitive behaviors in mice.

BACKGROUND: Repetitive behavior is a term used to describe a wide variety of invariant and inappropriate behaviors that occur in many diverse conditions, including autism. It is necessary to utilize and/or design rodent behavioral assays that exploit individual types of repetitive behavior so that underlying pathology and therapeutic measures can be determined. A variety of high-throughput assays to investigate lower order repetitive behaviors are available for rodents, whereas, fewer assays are available to investigate higher order repetitive behaviors, such as perseverative behavior. BTBR T(+)tf/J (BTBR) mice, harbor behavioral deficits that share similarity to the core deficits found in autism, yet have not conclusively demonstrated deficits in conventional reversal learning tasks (i.e. Morris water maze (MWM), T-maze) which are typically used to examine perseverance. NEW METHOD: By combining elements of both the MWM and T-maze, we designed a water T-maze assay to determine if perseverative behavior could become perceptible in BTBR mice. RESULTS: We found that BTBR mice show a significant impairment in reversal learning as compared to C57BL/6J (B6) mice in our water-T-maze reversal learning assay. COMPARISON OF EXISTING METHODS: Our water T-maze is sensitive, simple to perform, inexpensive and less time intensive than other tasks that can be used to measure higher order repetitive behaviors. CONCLUSIONS: Our findings suggest that our water T-maze assay is effective for determining perseverance, which is not readily revealed by using conventional methods.

Cued and contextual fear conditioning in BTBR mice is improved with training or atomoxetine.

The BTBR T+tf/J (BTBR) strain of mice is a model for autism spectrum disorders (ASDs). These mice display reduced social behavior, altered communication, and high levels of repetitive behavior. BTBR mice have shown a deficit in learning cued and contextual fear conditioning. In this study, experiments were conducted to determine if either changes in training or drug administration would improve learning in BTBR mice when compared to C57BL/6 (B6) mice in contextual and cued fear conditioning. The first experiment examined the effects of three conditioned stimulus-unconditioned stimulus (CS-US) training paradigms; a 1P (1 CS-US pairing), 4P (4 CS-US pairings), and 10P (10 CS-US pairings). Increasing the number of CS-US pairings to 10 caused an increase in freezing behavior by the BTBR mice in contextual and cued conditioning indicating that more training facilitated BTBR learning. B6 mice had a more complex reaction to the increased training; the mice increased freezing behavior in the cued fear conditioning but not contextual fear conditioning. The second experiment determined whether atomoxetine, a noradrenergic reuptake inhibitor that has been shown to improve attention and decrease hyperactivity, impulsivity, and social withdrawal, would enhance learning. There was a significant increase in freezing behavior in contextual fear conditioning following atomoxetine administration in BTBR mice but not in B6 mice. Our data demonstrates that contextual and cued learning in BTBR mice is facilitated by increased training. Furthermore, contextual learning is improved in BTBR mice with use of atomoxetine, which helps to improve attention. Both increased training and pharmacological intervention improved learning in the BTBR mice suggesting a role for the combination of the two.

Assessment of social interaction and anxiety-like behavior in senescence-accelerated-prone and -resistant mice.

Two members of the senescence-accelerated mouse group, SAMP8 and SAMP10, are characterized by learning and memory deficits, while the SAMR1 strain is not. In this study, we used two behavioral tests, social approach and object recognition and compared the results observed for the SAMP strains with those seen in the control strain, SAMR1. In social approach experiments, the 2 SAMP strains showed decreased sociability compared to SAMR1 as shown by their reluctance to spend time near a stranger mouse and increased immobility. In object recognition experiments, SAMP strains spent more time in the thigmotaxis zone and less time in the more exposed central zone than SAMR1 mice. From a behavioral standpoint, SAMP mice were less interactive and showed increased anxiety-like behavior compared to SAMR1.

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

INTRODUCTION: Currently, there is not an effective pharmacotherapy for the core symptoms of the autism spectrum disorders (ASD), which include aberrant social behavior, delayed communication and repetitive behavior and/or restricted interests. There are several drugs that treat the symptoms associated with autism including irritability, aggressiveness and hyperactivity. Current drug research is based on the ongoing genetic, animal model and neuropathologic research. Two areas in particular, the glutamate and oxytocin systems, provide exciting new avenues for drug discovery. AREAS COVERED: This review examines what approaches have been used for the drugs that are currently being used to treat people with ASD. For the most part, drugs that treat other neuropsychiatric disorders have been examined to treat the people with ASD, unfortunately with little effect on the core symptoms. EXPERT OPINION: Until recently, there was not a plethora of knowledge about the neurobiological substrates of social behavior, pragmatic language usage and repetitive and/or restricted behaviors. Therefore, drug discovery has used the tools available for other neuropsychiatric disorders. Now that more biological information is available, there are many avenues for research for drug targets for ASD.

Brain IL-6 elevation causes neuronal circuitry imbalances and mediates autism-like behaviors.

Abnormal immune responses have been reported to be associated with autism. A number of studies showed that cytokines were increased in the blood, brain, and cerebrospinal fluid of autistic subjects. Elevated IL-6 in autistic brain has been a consistent finding. However, the mechanisms by which IL-6 may be involved in the pathogenesis of autism are not well understood. Here we show that mice with elevated IL-6 in the brain display many autistic features, including impaired cognitive abilities, deficits in learning, abnormal anxiety traits and habituations, as well as decreased social interactions. IL-6 elevation caused alterations in excitatory and inhibitory synaptic formations and disrupted the balance of excitatory/inhibitory synaptic transmissions. IL-6 elevation also resulted in an abnormal change in the shape, length and distributing pattern of dendritic spines. These findings suggest that IL-6 elevation in the brain could mediate autistic-like behaviors, possibly through the imbalances of neural circuitry and impairments of synaptic plasticity.

Chlorination byproducts induce gender specific autistic-like behaviors in CD-1 mice.

In 2000, the Agency for Toxic Substances and Disease Registry (ATSDR) released a report concerning elevated autism prevalence and the presence water chlorination byproducts in the municipal drinking water supply in Brick Township, New Jersey. The ATSDR concluded that it was unlikely that these chemicals, specifically chloroform, bromoform (Trihalomethanes; THMs) and tetrachloroethylene (Perchloroethylene; PCE) had contributed to the prevalence of autism in this community based upon correlations between timing of exposure and/or concentration of exposure. The ATSDR conclusion may have been premature, as there is no conclusive data evidencing a correlation between a particular developmental time point that would render an individual most susceptible to toxicological insult with the development of autism. Therefore, it was our aim to determine if these chemicals could contribute to autistic like behaviors. We found that males treated with THMs and PCE have a significant reduction in the number of ultrasonic vocalizations (USVs) emitted in response to maternal separation, which are not attributed to deficits in vocal ability to or to lesser maternal care. These same males also show significantly elevated anxiety, an increase in perseverance behavior and a significant reduction in sociability. The sum of our data suggests that male, but not female mice, develop autistic like behaviors after gestational and postnatal exposure to the aforementioned chemical triad via drinking water. We believe development of such aberrant behaviors likely involves GABAergic system development.