Autism‐related behaviors in the cyclooxygenase‐2‐deficient mouse model

Prostaglandin E2 (PGE2) is an endogenous lipid molecule involved in normal brain development. Cyclooxygenase‐2 (COX2) is the main regulator of PGE2 synthesis. Emerging clinical and molecular research provides compelling evidence that abnormal COX2/PGE2 signaling is associated with autism spectrum disorder (ASD). We previously found that COX2 knockout mice had dysregulated expression of many ASD genes belonging to important biological pathways for neurodevelopment. The present study is the first to show the connection between irregular COX2/PGE2 signaling and autism‐related behaviors in male and female COX2‐deficient knockin, (COX)‐2^?, mice at young (4‐6 weeks) or adult (8‐11 weeks) ages. Autism‐related behaviors were prominent in male (COX)‐2^? mice for most behavioral tests. In the open field test, (COX)‐2^? mice traveled more than controls and adult male (COX)‐2^? mice spent less time in the center indicating elevated hyperactive and anxiety‐linked behaviors. (COX)‐2^? mice also buried more marbles, with males burying more than females, suggesting increased anxiety and repetitive behaviors. Young male (COX)‐2^? mice fell more frequently in the inverted screen test revealing motor deficits. The three‐chamber sociability test found that adult female (COX)‐2^? mice spent less time in the novel mouse chamber indicative of social abnormalities. In addition, male (COX)‐2^? mice showed altered expression of several autism‐linked genes: Wnt2, Glo1, Grm5 and Mmp9. Overall, our findings offer new insight into the involvement of disrupted COX2/PGE2 signaling in ASD pathology with age‐related differences and greater impact on males. We propose that (COX)‐2^? mice might serve as a novel model system to study specific types of autism.     

Maternal and offspring methylenetetrahydrofolate‐reductase genotypes interact in a mouse model to induce autism spectrum disorder‐like behavior

Individuals with autism constitute a variable population whose members are spread along the autism spectrum. Subpopulations within that spectrum exhibit other conditions, such as anxiety, intellectual disabilities, hyperactivity and epilepsy, with different severities and co‐occurrences. Among the genes associated with the increased risk for autism is the methylenetetrahydrofolate‐reductase (MTHFR) 677C>T polymorphism, which impairs one‐carbon (C1) metabolic pathway efficiency. The frequency of the MTHFR677TT homozygote is markedly higher among autism patients and their mothers than in the general population. Here, we report on the Mthfr heterozygous knockout (KO) mouse as a rodent model of autism that shows the contributions of maternal and offspring genotypes to the development of autistic‐like behaviors. Maternal Mthfr‐deficiency was associated with developmental delays in morphogenic features and sensory‐motor reflexes in offspring. In the adult male mouse, behaviors representing core autism symptoms, such as repetitive behavior and restricted interest, were affected by maternal genotype while social behaviors were affected by both maternal and offspring genotypes. In females and males, behaviors associated with autism such as memory impairment, social aggression and anxiety were affected by both the maternal and offspring Mthfr genotypes, with sex‐dependent differences. Mthfr‐deficient male mice with observable impacts on behavior presented a particular laminar disturbance in parvalbumin interneuron density and innervation in superficial and deep layers of the cingulate cortex. This mouse model of autism will help to elucidate the molecular mechanisms that predispose a significant subgroup of autistic patients to abnormal development and to distinguish between the in‐utero and autonomous factors involved in autism.     

Emergence of layer IV barrel cytoarchitecture is delayed in somatosensory cortex of GAP-43 deficient mice following delayed development of dendritic asymmetry

The emergence of barrel cytoarchitecture in mouse somatosensory cortex is extremely well defined. However, mechanisms underlying the development of this cellular organization are not completely understood. While it is generally accepted that hollows emerge via passive displacement of cortical cells by dense thalamocortical afferent clusters in barrel centers, it is not known what causes cellular segregation of barrel sides and septa. Here, we hypothesized that the emergence of sides and septa is related to the progressive asymmetry of dendrites from the cells of the barrel side toward the barrel hollow during development. We tested this hypothesis in the barrel cortex of growth-associated protein-43 heterozygous mice (GAP43 (+/?) mice) that display a 2-day delay in retraction of septally oriented dendrites compared to (+/+) littermates. We predicted that this delayed retraction would result in a subsequent 2-day delay in the emergence of barrel sides and septa. Using cresyl violet staining of barrel cortex, we found that initial emergence of hollows was not different between GAP43 (+/?) mice and (+/+) littermate controls. However, the emergence of sides and septa was delayed by 2 days, supporting our hypothesis that the emergence of barrel sides and septa is related to, and perhaps reliant upon, the developmental step of dendritic orientation toward barrel hollows. This process, which is mechanistically distinct from the emergence of barrel hollows, is likely due to both active and passive events resulting from asymmetric cell orientation.     

Decreased aggression and increased repetitive behavior in Pten haploinsufficient mice

Aggression is an aspect of social behavior that can be elevated in some individuals with autism spectrum disorder (ASD) and a concern for peers and caregivers. Mutations in Phosphatase and tensin homolog (PTEN), one of several ASD risk factors encoding negative regulators of the PI3K–Akt–mTOR pathway, have been reported in individuals with ASD and comorbid macrocephaly. We previously showed that a mouse model of Pten germline haploinsufficiency (Pten^+/?) has selective deficits, primarily in social behavior, along with broad overgrowth of the brain. Here, we further examine the social behavior of Pten^+/? male mice in the resident–intruder test of aggression, using a comprehensive behavioral analysis to obtain an overall picture of the agonistic, non‐agonistic and non‐social behavior patterns of Pten^+/? mice during a free interaction with a novel conspecific. Pten^+/? male mice were involved in less aggression than their wild‐type littermates. Pten^+/? mice also performed less social investigation, including anogenital investigation and approaching and/or attending to the intruder, which is consistent with our previous finding of decreased sociability in the social approach test. In contrast to these decreases in social behaviors, Pten^+/? mice showed increased digging. In summary, we report decreased aggression and increased repetitive behavior in Pten^+/? mice, thus extending our characterization of this model of an ASD risk factor that features brain overgrowth and social deficits.     

Heterozygous loss of epilepsy gene KCNQ2 alters social,repetitive and exploratory behaviors

KCNQ/K_v7 channels conduct voltage‐dependent outward potassium currents that potently decrease neuronal excitability. Heterozygous inherited mutations in their principle subunits K_v7.2/KCNQ2 and K_v7.3/KCNQ3 cause benign familial neonatal epilepsy whereas patients with de novo heterozygous K_v7.2 mutations are associated with early‐onset epileptic encephalopathy and neurodevelopmental disorders characterized by intellectual disability, developmental delay and autism. However, the role of K_v7.2‐containing K_v7 channels in behaviors especially autism‐associated behaviors has not been described. Because pathogenic K_v7.2 mutations in patients are typically heterozygous loss‐of‐function mutations, we investigated the contributions of K_v7.2 to exploratory, social, repetitive and compulsive‐like behaviors by behavioral phenotyping of both male and female KCNQ2^+/? mice that were heterozygous null for the KCNQ2 gene. Compared with their wild‐type littermates, male and female KCNQ2^+/? mice displayed increased locomotor activity in their home cage during the light phase but not the dark phase and showed no difference in motor coordination, suggesting hyperactivity during the inactive light phase. In the dark phase, KCNQ2^+/? group showed enhanced exploratory behaviors, and repetitive grooming but decreased sociability with sex differences in the degree of these behaviors. While male KCNQ2^+/? mice displayed enhanced compulsive‐like behavior and social dominance, female KCNQ2^+/? mice did not. In addition to elevated seizure susceptibility, our findings together indicate that heterozygous loss of K_v7.2 induces behavioral abnormalities including autism‐associated behaviors such as reduced sociability and enhanced repetitive behaviors. Therefore, our study is the first to provide a tangible link between loss‐of‐function K_v7.2 mutations and the behavioral comorbidities of K_v7.2‐associated epilepsy.     

Magel2 knockout mice manifest altered social phenotypes and a deficit in preference for social novelty

MAGEL2 is one of five protein‐coding, maternally imprinted, paternally expressed genes in the Prader–Willi syndrome (PWS)‐critical domain on chromosome 15q11‐q13. Truncating pathogenic variants of MAGEL2 cause Schaaf‐Yang syndrome (SHFYNG) (OMIM #615547), a neurodevelopmental disorder related to PWS. Affected individuals manifest a spectrum of neurocognitive and behavioral phenotypes, including intellectual disability and autism spectrum disorder (ASD). Magel2 knockout mice carrying a maternally inherited, imprinted wild‐type (WT) allele and a paternally inherited Magel2‐lacZ knock‐in allele, which abolishes endogenous Magel2 gene function, exhibit several features reminiscent of the human Prader–Willi phenotypes, including neonatal growth retardation, excessive weight gain after weaning and increased adiposity in adulthood. They were shown to have altered circadian rhythm, reduced motor activity and reduced fertility. An extensive assessment for autism‐like behaviors in this mouse model was warranted, because of the high prevalence of ASD in human patients. The behavior of Magel2 knockout mice and their WT littermates were assayed via open field, elevated plus maze, tube, three‐chamber and partition tests. Our studies confirm decreased horizontal activity of male and female mice and increased vertical activity of females, in the open field. Both sexes spent more time in the open arm of the elevated plus maze, suggestive of reductions in anxiety. Both sexes displayed a lack of preference for social novelty, via a lack of discrimination between known and novel partners in the partition test. The in‐depth investigation of behavioral profiles caused by Magel2 loss‐of‐function helps to elucidate the etiology of behavioral phenotypes both for SHFYNG and PWS in general.     

Behavioral phenotypes in males with XYY and possible role of increased NLGN4Y expression in autism features

The male sex chromosome disorder, 47,XYY syndrome (XYY), is associated with increased risk for social‐emotional difficulties, attention‐deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). We hypothesize that increased Y chromosome gene copy number in XYY leads to overexpression of Y‐linked genes related to brain development and function, thereby increasing risk for these phenotypes. We measured expression in blood of two Y genes NLGN4Y and RPS4Y in 26 boys with XYY and 11 male controls and evaluated whether NLGN4Y expression correlates with anxiety, ADHD, depression and autistic behaviors (from questionnaires) in boys with XYY. The XYY cohort had increased risk of ASD behaviors on the social responsiveness scale (SRS) and increased attention deficits on the Conners' DSM‐IV inattention and hyperactive scales. In contrast, there was no increase in reported symptoms of anxiety or depression by the XYY group. Peripheral expression of two Y genes in boys with XYY vs. typically developing controls was increased twofold in the XYY group. Results from the SRS total and autistic mannerisms scales, but not from the attention, anxiety or depression measures, correlated with peripheral expression of NLGN4Y in boys with XYY. Males with XYY have social phenotypes that include increased risk for autism‐related behaviors and ADHD. Expression of NLGN4Y, a gene that may be involved in synaptic function, is increased in boys with XYY, and the level of expression correlates with overall social responsiveness and autism symptoms. Thus, further investigation of NLGN4Y as a plausible ASD risk gene in XYY is warranted.     

Zfp462 deficiency causes anxiety‐like behaviors with excessive self‐grooming in mice

Zfp462 is a newly identified vertebrate‐specific zinc finger protein that contains nearly 2500 amino acids and 23 putative C2H2‐type zinc finger domains. So far, the functions of Zfp462 remain unclear. In our study, we showed that Zfp462 is expressed predominantly in the developing brain, especially in the cerebral cortex and hippocampus regions from embryonic day 7.5 to early postnatal stage. By using a piggyBac transposon‐generated Zfp462 knockout (KO) mouse model, we found that Zfp462 KO mice exhibited prenatal lethality with normal neural tube patterning, whereas heterozygous (Het) Zfp462 KO (Zfp462^+/?) mice showed developmental delay with low body weight and brain weight. Behavioral studies showed that Zfp462^+/? mice presented anxiety‐like behaviors with excessive self‐grooming and hair loss, which were similar to the pathological grooming behaviors in Hoxb8 KO mice. Further analysis of grooming microstructure showed the impairment of grooming patterning in Zfp462^+/? mice. In addition, the mRNA levels of Pbx1 (pre‐B‐cell leukemia homeobox 1, an interacting protein of Zfp462) and Hoxb8 decreased in the brains of Zfp462^+/? mice, which may be the cause of anxiety‐like behaviors. Finally, imipramine, a widely used and effective anti‐anxiety medicine, rescued anxiety‐like behaviors and excessive self‐grooming in Zfp462^+/? mice. In conclusion, Zfp462 deficiency causes anxiety‐like behaviors with excessive self‐grooming in mice. This provides a novel genetic mouse model for anxiety disorders and a useful tool to determine potential therapeutic targets for anxiety disorders and screen anti‐anxiety drugs.     

Increased aggression and lack of maternal behavior in Dio3‐deficient mice are associated with abnormalities in oxytocin and vasopressin systems

Thyroid hormones regulate many aspects of brain development and function, and alterations in the levels of thyroid hormone action lead to abnormal anxiety‐ and depression‐like behaviors. A complement of factors in the brain function independently of circulating levels of hormone to strictly controlled local thyroid hormone signaling. A critical factor is the type 3 deiodinase (DIO3), which is located in neurons and protects the brain from excessive thyroid hormone. Here, we examined whether a local increase in brain thyroid hormone action secondary to DIO3 deficiency is of consequence for social behaviors. Although we did not observe alterations in sociability, Dio3?/? mice of both sexes exhibited a significant increase in aggression‐related behaviors and mild deficits in olfactory function. In addition, 85% of Dio3?/? dams manifested no pup‐retrieval behavior and increased aggression toward the newborns. The abnormal social behaviors of Dio3?/? mice were associated with sexually dimorphic alterations in the physiology of oxytocin (OXT) and arginine vasopressin (AVP), 2 neuropeptides with important roles in determining social interactions. These alterations included low adult serum levels of OXT and AVP, and an abnormal expression of Oxt, Avp and their receptors in the neonatal and adult hypothalamus. Our results demonstrate that DIO3 is essential for normal aggression and maternal behaviors, and indicate that abnormal local regulation of thyroid hormone action in the brain may contribute to the social deficits associated with neurodevelopmental disorders.     

HCN4 knockdown in dorsal hippocampus promotes anxiety‐like behavior in mice

Hyperpolarization‐activated and cyclic nucleotide‐gated (HCN) channels mediate the I_h current in the murine hippocampus. Disruption of the I_h current by knockout of HCN1, HCN2 or tetratricopeptide repeat‐containing Rab8b‐interacting protein has been shown to affect physiological processes such as synaptic integration and maintenance of resting membrane potentials as well as several behaviors in mice, including depressive‐like and anxiety‐like behaviors. However, the potential involvement of the HCN4 isoform in these processes is unknown. Here, we assessed the contribution of the HCN4 isoform to neuronal processing and hippocampus‐based behaviors in mice. We show that HCN4 is expressed in various regions of the hippocampus, with distinct expression patterns that partially overlapped with other HCN isoforms. For behavioral analysis, we specifically modulated HCN4 expression by injecting recombinant adeno‐associated viral (rAAV) vectors mediating expression of short hairpin RNA against hcn4 (shHcn4) into the dorsal hippocampus of mice. HCN4 knockdown produced no effect on contextual fear conditioning or spatial memory. However, a pronounced anxiogenic effect was evident in mice treated with shHcn4 compared to control littermates. Our findings suggest that HCN4 specifically contributes to anxiety‐like behaviors in mice.     

Growth‐associated protein 43 promotes thyroid cancer cell lines progression via epithelial‐mesenchymal transition

Thyroid cancer is maintaining at a high incidence level and its carcinogenesis is mainly affected by a complex gene interaction. By analysis of the next‐generation resequencing of paired papillary thyroid cancer (PTC) and adjacent thyroid tissues, we found that Growth Associated Protein 43 (GAP43), a phosphoprotein activated by protein kinase C, might be novel markers associated with PTC. However, its function in thyroid carcinoma has been poorly understood. We discovered that GAP43 was significantly overexpressed in thyroid carcinoma and these results were consistent with that in The Cancer Genome Atlas (TCGA) cohort. In addition, some clinicopathological features of GAP43 in TCGA database showed that up‐regulated GAP43 is significantly connected to lymph node metastasis (P < 0.001) and tumour size (P = 0.038). In vitro experiments, loss of function experiments was performed to investigate GAP43 in PTC cell lines (TPC‐1 and BCPAP). The results proved that GAP43 knockdown in PTC cell significantly decreased the function of cell proliferation, colony formation, migration, and invasion and induced cell apoptosis. Furthermore, we also indicated that GAP43 could modulate the expression of epithelial‐mesenchymal transition‐related proteins, which could influence invasion and migration. Put those results together, GAP43 is a gene which was associated with PTC and might be a potential therapeutic target.     

Activity‐regulated cytoskeleton‐associated protein (Arc/Arg3.1) regulates anxiety‐ and novelty‐related behaviors

The activity‐regulated cytoskeleton‐associated protein (Arc, also known as Arg3.1) regulates glutamatergic synapse plasticity and has been linked to neuropsychiatric illness; however, its role in behaviors associated with mood and anxiety disorders remains unclear. We find that stress upregulates Arc expression in the adult mouse nucleus accumbens (NAc)—a brain region implicated in mood and anxiety behaviors. Global Arc knockout mice have altered AMPAR‐subunit surface levels in the adult NAc, and the Arc‐deficient mice show reductions in anxiety‐like behavior, deficits in social novelty preference, and antidepressive‐like behavior. Viral‐mediated expression of Arc in the adult NAc of male, global Arc KO mice restores normal levels of anxiety‐like behavior in the elevated plus maze (EPM). Consistent with this finding, viral‐mediated reduction of Arc in the adult NAc reduces anxiety‐like behavior in male, but not female, mice in the EPM. NAc‐specific reduction of Arc also produced significant deficits in both object and social novelty preference tasks. Together our findings indicate that Arc is essential for regulating normal mood‐ and anxiety‐related behaviors and novelty discrimination, and that Arc's function within the adult NAc contributes to these behavioral effects.     

Lithium treatment alleviates impaired cognition in a mouse model of fragile X syndrome

Fragile X syndrome (FXS) is caused by suppressed expression of fragile X mental retardation protein (FMRP), which results in intellectual disability accompanied by many variably manifested characteristics, such as hyperactivity, seizures and autistic‐like behaviors. Treatment of mice that lack FMRP, Fmr1 knockout (KO) mice, with lithium has been reported to ameliorate locomotor hyperactivity, prevent hypersensitivity to audiogenic seizures, improve passive avoidance behavior and attenuate sociability deficits. To focus on the defining characteristic of FXS, which is cognitive impairment, we tested if lithium treatment ameliorated impairments in four cognitive tasks in Fmr1 KO mice, tested if the response to lithium differed in adolescent and adult mice and tested if therapeutic effects persisted after discontinuation of lithium administration. Fmr1 KO mice displayed impaired cognition in the novel object detection task, temporal ordering for objects task and coordinate and categorical spatial processing tasks. Chronic lithium treatment of adolescent (from 4 to 8 weeks of age) and adult (from 8 to 12 weeks of age) mice abolished cognitive impairments in all four cognitive tasks. Cognitive deficits returned after lithium treatment was discontinued for 4 weeks. These results show that Fmr1 KO mice exhibit severe impairments in these cognitive tasks, that lithium is equally effective in normalizing cognition in these tasks whether it is administered to young or adult mice and that lithium administration must be continued for the cognitive improvements to be sustained. These findings provide further evidence that lithium administration may be beneficial for individuals with FXS .     

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, {"type":"entrez-protein","attrs":{"text":"SKF83822","term_id":"1156217297"}}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.     

Absence of deficits in social behaviors and ultrasonic vocalizations in later generations of mice lacking neuroligin4

Mutations in NLGN4X have been identified in individuals with autism spectrum disorders and other neurodevelopmental disorders. A previous study reported that adult male mice lacking neuroligin4 (Nlgn4) displayed social approach deficits in the three‐chambered test, altered aggressive behaviors and reduced ultrasonic vocalizations. To replicate and extend these findings, independent comprehensive analyses of autism‐relevant behavioral phenotypes were conducted in later generations of the same line of Nlgn4 mutant mice at the National Institute of Mental Health in Bethesda, MD, USA and at the Institut Pasteur in Paris, France. Adult social approach was normal in all three genotypes of Nlgn4 mice tested at both sites. Reciprocal social interactions in juveniles were similarly normal across genotypes. No genotype differences were detected in ultrasonic vocalizations in pups separated from the nest or in adults during reciprocal social interactions. Anxiety‐like behaviors, self‐grooming, rotarod and open field exploration did not differ across genotypes, and measures of developmental milestones and general health were normal. Our findings indicate an absence of autism‐relevant behavioral phenotypes in subsequent generations of Nlgn4 mice tested at two locations. Testing environment and methods differed from the original study in some aspects, although the presence of normal sociability was seen in all genotypes when methods taken from Jamain et al. (2008) were used. The divergent results obtained from this study indicate that phenotypes may not be replicable across breeding generations, and highlight the significant roles of environmental, generational and/or procedural factors on behavioral phenotypes.     

Methyl‐CpG‐binding protein 2 polymorphisms and vulnerability to autism

The methyl‐binding protein gene, MECP2, is a candidate for involvement in autism through its implication as a major causative factor in Rett syndrome that has similarities to autism. Rare mutations in MECP2 have also been identified in autistic individuals. We have examined the possible broader involvement of MECP2 as a predisposing factor in the disorder. Analysis of polymorphic markers spanning the gene and comprising both microsatellites and single nucleotide polymorphisms (SNPs) by the transmission disequilibrium test in two collections of families (219 in total), one in the USA and one in the UK, has provided evidence for significant association (P = 0.009) for a three‐marker SNP haplotype of MECP2 with autism/autism spectrum disorders. This association is supported by association of both Single Sequence Repeat (SSR) and SNP single markers located at the 3′ end of the MECP2 locus and flanking sequence, the most significant being that of an indel marker located in intron 2 (P = 0.001 – Bonferroni corrected P = 0.006). This suggests that one or more functional variants of MECP2 existing at significant frequencies in the population may confer increased risk of autism/autism spectrum disorders and warrants further investigation in additional independent samples.     

Subchronic Treatment of Donepezil Rescues Impaired Social,Hyperactive, and Stereotypic Behavior in Valproic Acid-Induced Animal Model of Autism

Autism spectrum disorder (ASD) is a group of pervasive developmental disorders with core symptoms such as sociability deficit, language impairment, and repetitive/restricted behaviors. Although worldwide prevalence of ASD has been increased continuously, therapeutic agents to ameliorate the core symptoms especially social deficits, are very limited. In this study, we investigated therapeutic potential of donepezil for ASD using valproic acid-induced autistic animal model (VPA animal model). We found that prenatal exposure of valproic acid (VPA) induced dysregulation of cholinergic neuronal development, most notably the up-regulation of acetylcholinesterase (AChE) in the prefrontal cortex of affected rat and mouse offspring. Similarly, differentiating cortical neural progenitor cell in culture treated with VPA showed increased expression of AChE in vitro. Chromatin precipitation experiments revealed that acetylation of histone H3 bound to AChE promoter region was increased by VPA. In addition, other histone deacetyalse inhibitors (HDACIs) such as trichostatin A and sodium butyrate also increased the expression of AChE in differentiating neural progenitor cells suggesting the essential role of HDACIs in the regulation of AChE expression. For behavioral analysis, we injected PBS or donepezil (0.3 mg/kg) intraperitoneally to control and VPA mice once daily from postnatal day 14 all throughout the experiment. Subchronic treatment of donepezil improved sociability and prevented repetitive behavior and hyperactivity of VPA-treated mice offspring. Taken together, these results provide evidence that dysregulation of ACh system represented by the up-regulation of AChE may serve as an effective pharmacological therapeutic target against autistic behaviors in VPA animal model of ASD, which should be subjected for further investigation to verify the clinical relevance.     

Glutamic acid decarboxylase 67 haplodeficiency impairs social behavior in mice

Reduced glutamic acid decarboxylase (GAD)67 expression may be causally involved in the development of social withdrawal in neuropsychiatric states such as autism, schizophrenia and bipolar disorder. In this study, we report disturbance of social behavior in male GAD67 haplodeficient mice. GAD67^+/? mice, compared to GAD67^+/+ littermates, show reduced sociability and decreased intermale aggression, but normal nest building and urine marking behavior, as well as unchanged locomotor activity and anxiety‐like behavior. Moreover, the mutants display a reduced sensitivity to both social and non‐social odors, indicating a disturbance in the detection and/or processing of socially relevant olfactory stimuli. Indeed, we observed reduced activation of the lateral septum, medial preoptic area, bed nucleus of the stria terminalis, medial and cortical amygdala upon exposure of GAD67^+/? mice to social interaction paradigm, as indicated by c‐Fos immunohistochemistry. These data suggest a disturbance of stimulus processing in the brain circuitry controlling social behavior in GAD67^+/? mice, which may provide a useful model for studying the impact of a reduced GAD67 expression on alterations of social behavior related to neuropsychiatric disorders .     

A HuD‐ZBP1 ribonucleoprotein complex localizes GAP‐43 mRNA into axons through its 3′ untranslated region AU‐rich regulatory element

Localized translation of axonal mRNAs contributes to developmental and regenerative axon growth. Although untranslated regions (UTRs) of many different axonal mRNAs appear to drive their localization, there has been no consensus RNA structure responsible for this localization. We recently showed that limited expression of ZBP1 protein restricts axonal localization of both β‐actin and GAP‐43 mRNAs. β‐actin 3′UTR has a defined element for interaction with ZBP1, but GAP‐43 mRNA shows no homology to this RNA sequence. Here, we show that an AU‐rich regulatory element (ARE) in GAP‐43′s 3′UTR is necessary and sufficient for its axonal localization. Axonal GAP‐43 mRNA levels increase after in vivo injury, and GAP‐43 mRNA shows an increased half‐life in regenerating axons. GAP‐43 mRNA interacts with both HuD and ZBP1, and HuD and ZBP1 co‐immunoprecipitate in an RNA‐dependent fashion. Reporter mRNA with the GAP‐43 ARE competes with endogenous β‐actin mRNA for axonal localization and decreases axon length and branching similar to the β‐actin 3′UTR competing with endogenous GAP‐43 mRNA. Conversely, over‐expressing GAP‐43 coding sequence with its 3′UTR ARE increases axonal elongation and this effect is lost when just the ARE is deleted from GAP‐43′s 3′UTR.