Sara R. Guariglia

Mutation of SIMPLE in Charcot–Marie–Tooth 1C alters production of exosomes

Mutations in the protein SIMPLE account for the rare autosomal-dominant demyelination in type 1C CMT patients (CMT1C). SIMPLE plays a role in the production of exosomes. Dysregulated endosomal trafficking and changes in exosome-mediated intercellular communications might account for CMT1C molecular pathogenesis.

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.

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.

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.

Characterization of Induced Pluripotent Stem Cell Microvesicle Genesis, Morphology and Pluripotent Content

Microvesicles (MVs) are lipid bilayer-covered cell fragments that range in diameter from 30 nm–1uM and are released from all cell types. An increasing number of studies reveal that MVs contain microRNA, mRNA and protein that can be detected in the extracellular space. In this study, we characterized induced pluripotent stem cell (iPSC) MV genesis, content and fusion to retinal progenitor cells (RPCs) in vitro. Nanoparticle tracking revealed that iPSCs released approximately 2200 MVs cell/hour in the first 12 hrs with an average diameter of 122 nm. Electron and light microscopic analysis of iPSCs showed MV release via lipid bilayer budding. The mRNA content of iPSC MVs was characterized and revealed the presence of the transcription factors Oct-3/4, Nanog, Klf4, and C-Myc. The protein content of iPSCs MVs, detected by immunogold electron microscopy, revealed the presence of the Oct-3/4 and Nanog. Isolated iPSC MVs were shown to fuse with RPCs in vitro at multiple points along the plasma membrane. These findings demonstrate that the mRNA and protein cargo in iPSC MVs have established roles in maintenance of pluripotency. Building on this work, iPSC derived MVs may be shown to be involved in maintaining cellular pluripotency and may have application in regenerative strategies for neural tissue.

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.

Taurine's effects on the neuroendocrine functions of pancreatic β cells.

Taurine plays significant physiological roles, including those involved in neurotransmission. Taurine is a potent γ-aminobutyric acid (GABA) agonist and alters cellular events via GABA(A) receptors. Alternately, taurine is transported into cells via the high affinity taurine transporter (TauT), where it may also play a regulatory role. We have previously demonstrated that treatment of Hit-T15 cells with 1 mM taurine for 24 h significantly decreases insulin and GABA levels. We have also demonstrated that chronic in vivo administration of taurine results in an up-regulation of glutamic acid decarboxylase (GAD), the key enzyme in GABA synthesis. Here, we wished to test if administration of 1 mM taurine for 24 h may increase release of another β cell neurotransmitter somatostatin (SST) and also directly impact up-regulation of GAD synthesis. Treatment with taurine did not significantly alter levels of SST (p > 0.05) or GAD67 (p > 0.05). This suggests that taurine does not directly affect SST release, nor does it directly affect GAD synthesis. Taken together with our observation that taurine does promote GABA release via large dense-core vesicles, the data suggest that taurine may alter membrane potential, which in turn would affect calcium flux. We show here that 1 mM taurine does not alter intracellular Ca(2+) concentrations from 20 to 80 s post treatment (p > 0.05), but does increase Ca(2+) flux between 80 and 200 s post-treatment (p < 0.005). This suggests that taurine may induce a biphasic response in β cells. The initial response of taurine via GABA(A) receptors hyperpolarizes β cell and sequesters Ca(2+). Subsequently, taurine may affect Ca(2+) flux in long term via interaction with K(ATP) channels.

The BTBR T+ tf /J (BTBR) Mouse Model of Autism

Mouse models of neuropsychiatric disorders are validated according to three different criteria: face validity, construct validity and predictive validity. Autism Spectrum Disorders (ASDs) are diagnosed behaviorally, therefore, mouse models of ASDs rely primarily on face validity. The three diagnostic criteria for ASDs are impairments in social interaction, communication and repetitive behavior, and/or restricted interests. The BTBR T+tf/J (BTBR) mice are an inbred strain used as model of ASDs. All three types of behavioral criteria have been evaluated in the BTBR mice. An advantage of using an inbred strain, such as BTBR is that, the mice are considered genetically identical and offer good controls for experimentation. The BTBR mice have demonstrated face validity for the three core behaviors that define ASDs. Low levels of social behavior, altered communication and spontaneous grooming comprise the behavioral phenotype of the BTBR mice. For construct validity, the BTBR mice have some physiological characteristics similar to humans with ASDs. Several drug and behavioral treatments for ASDs have been examined in the BTBR mice; however this area of research is still being developed. This review will offer a description of the behavior and physiology of the BTBR mice as a model for ASDs.