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Autism Spectrum Disorder (ASD) is a developmental condition characterized by core symptoms including social difficulties, repetitive behaviors, and sensory abnormalities. Aberrant morphology of dendritic spines within the cortex has been documented in genetic disorders associated with ASD and ASD-like traits. We hypothesized that compounds that ameliorate abnormalities in spine dynamics might have the potential to ameliorate core symptoms of ASD. Because the morphology of the spine is influenced by signal inputs from other neurons and various molecular interactions, conventional singlemolecule targeted drug discovery methods may not suffice in identifying compounds capable of ameliorating spine morphology abnormalities. In this study, we focused on spine phenotypes in the cortex using BTBR T+ Itpr3tf/J (BTBR) mice, which have been used as a model for idiopathic ASD in various studies. We established an in vitro compound screening system using primary cultured neurons from BTBR mice to faithfully represent the spine phenotype. The compound library mainly comprised substances with known target molecules and established safety profiles, including those approved or validated through human safety studies. Following screening of this specialized library containing 181 compounds, we identified 15 confirmed hit compounds. The molecular targets of these hit compounds were largely focused on the 5-hydroxytryptamine receptor (5-HTR). Furthermore, both 5-HT1AR agonist and 5-HT3R antagonist were common functional profiles in hit compounds. Vortioxetine, possessing dual attributes as a 5-HT1AR agonist and 5-HT3R antagonist, was administered to BTBR mice once daily for a period of 7 days. This intervention not only ameliorated their spine phenotype but also alleviated their social behavior abnormality. These results of vortioxetine supports the usefulness of a spine phenotype-based assay system as a potent drug discovery platform targeting ASD core symptoms. [ABSTRACT FROM AUTHOR]

Hippocampal pyramidal neurons exhibit diverse spike patterns and gene expression profiles. However, their relationships with single neurons are not fully understood. In this study, we designed an electrophysiology-based experimental procedure to identify gene expression profiles using RNA sequencing of single hippocampal pyramidal neurons whose spike patterns were recorded in living mice. This technique involves a sequence of experiments consisting of in vivo juxtacellular recording and labeling, brain slicing, cell collection, and transcriptome analysis. We demonstrated that the expression levels of a subset of genes in individual hippocampal pyramidal neurons were significantly correlated with their spike burstiness, submillisecond-level spike rise times or spike rates, directly measured by in vivo electrophysiological recordings. Because this methodological approach can be applied across a wide range of brain regions, it is expected to contribute to studies on various neuronal heterogeneities to understand how physiological spike patterns are associated with gene expression profiles. [ABSTRACT FROM AUTHOR]

Background: Recently, the hypothesis that pathological α-Synuclein propagates from the gut to the brain has gained attention. Although results from animal studies support this hypothesis, the specific mechanism remains unclear. This study focused on the intestinal fatty acid-binding protein (FABP2), which is one of the subtypes of fatty acid binding proteins localizing in the gut, with the hypothesis that FABP2 is involved in the gut-to-brain propagation of α-Synuclein. The aim of this study was to clarify the pathological significance of FABP2 in the pathogenesis and progression of synucleinopathy. Methods: We examined the relationship between FABP2 and a-Synuclein in the uptake of α-Synuclein into enteric neurons using primary cultured neurons derived from mouse small intestinal myenteric plexus. We also quantified disease-related protein concentrations in the plasma of patients with synucleinopathy and related diseases, and analyzed the relationship between plasma FABP2 level and progression of the disease. Results: Experiments on α-Synuclein uptake in primary cultured enteric neurons showed that following uptake, α-Synuclein was concentrated in areas where FABP2 was localized. Moreover, analysis of the plasma protein levels of patients with Parkinson's disease revealed that the plasma FABP2 and α-Synuclein levels fluctuate with disease duration. The FABP2/α-Synuclein ratio fluctuated more markedly than either FABP2 or α-Synuclein alone, depending on the duration of disease, indicating a higher discriminant ability of early Parkinson's disease patients from healthy patients. Conclusions: These results suggest that FABP2 potentially contributes to the pathogenesis and progression of α-Synucleinopathies. Thus, FABP2 is an important molecule that has the potential to elucidate the consistent mechanisms that lead from the prodromal phase to the onset and subsequent progression of synucleinopathies. [ABSTRACT FROM AUTHOR]

Hippocampal cells are central to spatial and predictive representations, and experience replays by place cells are crucial for learning and memory. Nonetheless, how hippocampal replay patterns dynamically change during the learning process remains to be elucidated. Here, we designed a spatial task in which rats learned a new behavioral trajectory for reward. We found that as rats updated their behavioral strategies for a novel salient location, hippocampal cell ensembles increased theta-sequences and sharp wave ripple-associated synchronous spikes that preferentially replayed salient locations and reward-related contexts in reverse order. The directionality and contents of the replays progressively varied with learning, including an optimized path that had never been exploited by the animals, suggesting prioritized replays of significant experiences on a predictive map. Online feedback blockade of sharp wave ripples during a learning process inhibited stabilizing optimized behavior. These results implicate learning-associated experience replays that act to learn and reinforce specific behavioral strategies. [ABSTRACT FROM AUTHOR]

The hippocampus contains place cells representing spaces in an environment, and these place cells have been suggested to play a fundamental role in the formation of a cognitive map for spatial processing. However, how alterations in the firing patterns of place cells in response to aversive events encode the locations tied to these aversive events is unknown. Here, we analyzed spiking patterns of place cell ensembles in the dorsal hippocampal CA1 region of rats performing a T-maze alternation task with an aversive air-puff stimulation applied at a specific location on one side of a trajectory. The intensity of the air puff was adjusted so that the rats decreased their running speed before passing the aversive location. The addition of the aversive stimulus induced reorganization of place cell ensembles on both left and right trajectories with and without the aversive stimulus, respectively. Specifically, the animals showed a more abundant spatial representation in the vicinity of the aversive location. Removing the aversive stimulus induced new spatial firing patterns on both of the trajectories that differed from those both before and during application of the aversive stimulus. These results demonstrate that hippocampal spatial maps are flexibly reorganized to represent particular aversive events. [ABSTRACT FROM AUTHOR]

Pancreatic ductal adenocarcinoma (PDA) is an aggressive malignant disease that is resistant to various chemotherapeutic agents and commonly relapses. Efficient elimination of metastasized PDA is critical for a positive post‑surgical treatment outcome. The present study analyzed the effect of the B‑cell lymphoma‑2 (Bcl‑2)/B‑cell lymphoma extra‑large (Bcl‑xL) inhibitor, ABT‑737, on paclitaxel‑induced PDA cell death. A total of 8 PDA cell lines were subjected to immunoblotting to compare the expression of Bcl‑2/Bcl‑xL and other factors associated with taxane resistance, including myeloid cell leukemia 1 and βIII‑tubulin (TUBB3). The viability of PDA cells was analyzed following treatment with paclitaxel alone or a combination treatment with ABT‑737 and paclitaxel. Treatment with the ABT‑737/paclitaxel combination induced PDA cell death at a lower concentration of paclitaxel compared with paclitaxel alone. In addition, the viable cell population at the saturation point of paclitaxel was also decreased by co‑treatment with ABT‑737. ABT‑737 lowered the half maximal inhibitory concentration (IC50) by >2‑fold in PDA cells with high Bcl‑2/Bcl‑xL expression, but not in PDA cells with low Bcl‑2/Bcl‑xL expression and high TUBB3 expression. Knockdown of Bcl‑xL lowered the IC50 of paclitaxel, but knockdown of TUBB3 did not. ABT‑737 sensitized PDA to paclitaxel‑induced cell death, and Bcl‑xL expression was a key determinant of its sensitivity. ABT‑737 is potential candidate for combination chemotherapy of PDA with high Bcl‑xL expression levels. [ABSTRACT FROM AUTHOR]

Sensory stimuli not only activate specific populations of cortical neurons but can also silence other populations. However, it remains unclear whether neuronal silencing per se leads to memory formation and behavioral expression. Here we show that mice can report optogenetic inactivation of auditory neuron ensembles by exhibiting fear responses or seeking a reward. Mice receiving pairings of footshock and silencing of a neuronal ensemble exhibited a fear response selectively to the subsequent silencing of the same ensemble. The valence of the neuronal silencing was preserved for at least 30 d and was susceptible to extinction training. When we silenced an ensemble in one side of auditory cortex for conditioning, silencing of an ensemble in another side induced no fear response. We also found that mice can find a reward based on the presence or absence of the silencing. Neuronal silencing was stored as working memory. Taken together, we propose that neuronal silencing without explicit activation in the cerebral cortex is enough to elicit a cognitive behavior. [ABSTRACT FROM AUTHOR]

Astrocytes generate local calcium (Ca2+) signals that are thought to regulate their functions. Visualization of these signals in the intact brain requires an imaging method with high spatiotemporal resolution. Here, we describe such a method using transgenic mice expressing the ultrasensitive ratiometric Ca2+ indicator yellow Cameleon-Nano 50 (YC-Nano50) in astrocytes. In these mice, we detected a unique pattern of Ca2+ signals. These occur spontaneously, predominantly in astrocytic fine processes, but not the cell body. Upon sensory stimulation, astrocytes initially responded with Ca2+ signals at fine processes, which then propagated to the cell body. These observations suggest that astrocytic fine processes function as a high-sensitivity detector of neuronal activities. Thus, the method provides a useful tool for studying the activity of astrocytes in brain physiology and pathology. [ABSTRACT FROM AUTHOR]

We introduce a new method to unveil the network connectivity among dozens of neurons in brain slice preparations. While synaptic inputs were whole cell recorded from given postsynaptic neurons, the spatiotemporal firing patterns of presynaptic neuron candidates were monitored en masse with functional multineuron calcium imaging, an optical technique that records action potential–evoked somatic calcium transients with single-cell resolution. By statistically screening the neurons that exhibited calcium transients immediately before the postsynaptic inputs, we identified the presynaptic cells that made synaptic connections onto the patch-clamped neurons. To enhance the detection power, we devised the following points: 1) [K+]ewas lowered and [Ca2+]eand [Mg2+]ewere elevated, to reduce background synaptic activity and minimize the failure rate of synaptic transmission; and 2) a small fraction of presynaptic neurons was specifically activated by glutamate applied iontophoretically through a glass pipette that was moved to survey the presynaptic network of interest ("trawling"). Then we could theoretically detect 96% of presynaptic neurons activated in the imaged regions with a 1% false-positive error rate. This on-line probing technique would be a promising tool in the study of the wiring topography of neuronal circuits. [ABSTRACT FROM AUTHOR]

Large-scale recording from a population of neurons is a promising strategy for approaching the study of complex brain functions. Taking advantage of the fact that action potentials reliably evoke transient calcium fluctuations in the cell body, functional multineuron calcium imaging (fMCI) monitors the suprathreshold activity of hundreds of neurons. However, a limitation of fMCI is its semi-manual procedure of spike extraction from somatic calcium fluctuations, which is not only time consuming but is also associated with human errors. Here we describe a novel automatic method that combines principal-component analysis and support vector machine. This simple algorithm determines the timings of the spikes in calcium fluorescence traces more rapidly and reliably than human operators. [ABSTRACT FROM AUTHOR]