Explore the vast range of titles available.

Down syndrome (DS) is a genetic disorder caused by trisomy 21 (T21). Over the past two decades, the use of mouse models has led to significant advances in the understanding of mechanisms underlying various phenotypic features and comorbidities secondary to T21 and even informed the design of clinical trials aimed at enhancing the cognitive abilities of persons with DS. In spite of its success, this approach has been plagued by all the typical limitations of rodent modeling of human disorders and diseases. Recently, several laboratories have succeeded in producing T21 human induced pluripotent stem cells (T21‐iPSCs) from individuals with DS, which is emerging as a promising complementary tool for the study of DS. Here, we describe the method by which we generated 10 T21‐iPSC lines from epithelial cells in urine samples, presumably from kidney epithelial origin, using nonintegrating episomal vectors. We also show that these iPSCs maintain chromosomal stability for well over 20 passages and are more sensitive to proteotoxic stress than euploid iPSCs. Furthermore, these iPSC lines can be differentiated into glutamatergic neurons and cardiomyocytes. By culturing urine‐derived cells and maximizing the efficiency of episomal vector transfection, we have been able to generate iPSCs noninvasively and effectively from participants with DS in an ongoing clinical trial, and thus address most shortcomings of previously generated T21‐iPSC lines. These techniques should extend the application of iPSCs in modeling DS and other neurodevelopmental and neurodegenerative disorders, and may lead to future human cell‐based platforms for high‐throughput drug screening. Stem Cells Translational Medicine 2017;6:1465–1476

The dorsal raphe nucleus (DR) and median raphe nucleus (MR) contain populations of glutamatergic and GABAergic neurons that regulate diverse behavioral functions. However, their whole-brain input-output circuits remain incompletely elucidated. We used viral tracing combined with fluorescence micro-optical sectioning tomography to generate a comprehensive whole-brain atlas of inputs and outputs of glutamatergic and GABAergic neurons in the DR and MR. We found that these neurons received inputs from similar upstream brain regions. The glutamatergic and GABAergic neurons in the same raphe nucleus had divergent projection patterns with differences in critical brain regions. Specifically, MR glutamatergic neurons projected to the lateral habenula through multiple pathways. Correlation and cluster analysis revealed that glutamatergic and GABAergic neurons in the same raphe nucleus received heterogeneous inputs and sent different collateral projections. This connectivity atlas further elucidates the anatomical architecture of the raphe nuclei, which could facilitate better understanding of their behavioral functions.

Schizophrenia is a serious mental disorder, and existing antipsychotic drugs show limited efficacy and cause unwanted side effects. The development of glutamatergic drugs for schizophrenia is currently challenging. Most functions of histamine in the brain are mediated by the histamine H₁ receptor; however, the role of the H₂ receptor (H₂R) is not quite clear, especially in schizophrenia. Here, we found that expression of H₂R in glutamatergic neurons of the frontal cortex was decreased in schizophrenia patients. Selective knockout of the H₂R gene (Hrh2) in glutamatergic neurons (CaMKIIα-Cre; Hrh2fl/fl ) induced schizophrenia-like phenotypes including sensorimotor gating deficits, increased susceptibility to hyperactivity, social withdrawal, anhedonia, and impaired working memory, as well as decreased firing of glutamatergic neurons in the medial prefrontal cortex (mPFC) in in vivo electrophysiological tests. Selective knockdown of H₂R in glutamatergic neurons in the mPFC but not those in the hippocampus also mimicked these schizophrenia-like phenotypes. Furthermore, electrophysiology experiments established that H₂R deficiency decreased the firing of glutamatergic neurons by enhancing the current through hyperpolarization-activated cyclic nucleotide-gated channels. In addition, either H₂R overexpression in glutamatergic neurons or H₂R agonism in the mPFC counteracted schizophrenia-like phenotypes in an MK-801-induced mouse model of schizophrenia. Taken together, our results suggest that deficit of H₂R in mPFC glutamatergic neurons may be pivotal to the pathogenesis of schizophrenia and that H₂R agonists can be regarded as potentially efficacious medications for schizophrenia therapy. The findings also provide evidence for enriching the conventional glutamate hypothesis for the pathogenesis of schizophrenia and improve the understanding of the functional role of H₂R in the brain, especially in glutamatergic neurons.

The accumulation of a disease-specific isoform of prion protein (PrP Sc ) and histopathological lesions, such as neuronal loss, are unevenly distributed in the brains of humans and animals affected with prion diseases. This distribution varies depending on the diseases and/or the combinations of prion strain and experimental animal. The brain region-dependent distribution of PrP Sc and neuropathological lesions suggests a neuronal cell-type-dependent prion propagation and vulnerability to prion infection. However, the underlying mechanism is largely unknown. In this study, we provided evidence that the prion 22L strain propagates more efficiently in excitatory neurons than inhibitory neurons and that excitatory neurons in the thalamus are vulnerable to prion infection. PrP Sc accumulation was less intense in the striatum, where GABAergic inhibitory neurons predominate, compared to the cerebral cortex and thalamus, where glutamatergic excitatory neurons are predominant, in mice intracerebrally or intraperitoneally inoculated with the 22L strain. PrP Sc stains were observed along the needle track after stereotaxic injection into the striatum, whereas they were also observed away from the needle track in the thalamus. Consistent with inefficient prion propagation in the striatum, the 22L prion propagated more efficiently in glutamatergic neurons than GABAergic neurons in primary neuronal cultures. RNAscope in situ hybridization revealed a decrease in Vglut1 - and Vglut2 -expressing neurons in the ventral posterolateral nuclei of the thalamus in 22L strain-infected mice, whereas no decrease in Vgat -expressing neurons was observed in the adjacent reticular nucleus, mainly composed of Vgat -expressing interneurons. The excitatory neuron-prone prion propagation and excitatory neuronal loss in 22L strain-infected mice shed light on the neuropathological mechanism of prion diseases.

Although electroacupuncture (EA) has become a worldwide practice, little is understood about its precise target in the central nervous system (CNS) and the cell type-specific analgesia mechanism. In the present study, we found that EA has significant antinociceptive effects both in inflammatory and neuropathic pain models. Chemogenetic inhibition of GABAergic neurons in the ventrolateral periaqueductal gray (vlPAG) replicated the effects of EA, whereas the combination of chemogenetic activation of GABAergic neurons and chemogenetic inhibition of glutamatergic neurons in the vlPAG was needed to reverse the effects of EA. Specifically knocking out CB1 receptors on GABAergic neurons in the vlPAG abolished the EA effect on pain hypersensitivity, while specifically knocking out CB1 receptors on glutamatergic neurons attenuated only a small portion of the EA effect. EA synchronously inhibits GABAergic neurons and activates glutamatergic neurons in the vlPAG through CB1 receptors to produce EA-induced analgesia. The CB1 receptors on GABAergic neurons localized in the vlPAG was the basis of the EA effect on pain hypersensitivity. This study provides new experimental evidence that EA can bidirectionally regulate GABAergic neurons and glutamatergic neurons via the CB1 receptors of the vlPAG to produce analgesia effects.

The mesencephalic locomotor region (MLR) encodes a diverse range of movements, from locomotion to posture and turning behavior. While the cuneiform nucleus (CnF) and pedunculopontine nucleus (PPN), the main components of the MLR, have been recently characterized, little is known about the precuneiform nucleus (PrCnF). To address this gap, we performed somatodendritic morphological analyses and ex vivo functional studies on PrCnF neurons of VGluT2-tdTomato mice and compared them with those of neighboring MLR nuclei. PrCnF neurons exhibited dendritic morphology similar to PPN neurons but distinct from CnF neurons. Functionally, PrCnF neurons displayed higher firing rates and oscillatory activity compared to CnF and PPN neurons, which were correlated with TTX-sensitive high-threshold membrane potential oscillations mediated by the persistent Na⁺ current present in most PrCnF neurons. Unlike PPN and CnF neurons, the majority of PrCnF neurons did not show depolarization-related changes in spike frequency adaptation, indicating that their intrinsic properties support continuous high-frequency spiking. These findings suggest that PrCnF neurons may have a uniform relationship to movement speed similar to CnF neurons and that activation of the PrCnF might be related to higher-speed movements due to their weak spike frequency adaptation and higher firing rates.

It has been reported that experimental pain can diminish cough sensitivity and that the lateral parabrachial nucleus (LPBN) coordinates pain with breathing, but whether the LPBN regulates cough-like behaviors and pain-induced changes in cough sensitivity remains elusive. We investigated the roles of LPBN γ-aminobutyric acidergic (GABAergic) and glutamatergic neurons in the regulation of cough sensitivity and its relationship with pain in mice via chemogenetic approaches. Adenovirus-associated virus tracing combined with chemogenetics was used to map the projections of LPBN GABAergic and glutamatergic neurons to the periaqueductal gray. LPBN neurons were activated by cough challenge, and nonspecific inhibition of LPBN neurons suppressed cough-like behavior. Chemogenetic suppression of LPBN GABAergic neurons reduced cough sensitivity in mice, whereas suppression of LPBN glutamatergic neurons counteracted the pain-driven decrease in cough sensitivity, and so did silencing LPBN glutamatergic neurons projecting to the periaqueductal gray. Our data suggest that GABAergic and glutamatergic neurons in the LPBN critically are involved in cough sensitivity and coordinate pain with cough through inhibitory or activating mechanisms at the midbrain level.

Developmental methylmercury (MeHg) exposures cause latent neurotoxic effects in adults; however, the mechanisms underlying the latent neurotoxicity are not fully understood. In the current study, we used C. elegans as an animal model to investigate the latent neurotoxic effects of developmental MeHg exposures on glutamatergic neurons. The young larvae stage 1 worms were exposed to MeHg (0.05 ~ 5 µM) for 48 h. The morphological and behavioral endpoints of glutamatergic neurons were compared when worms reached to adult stages including the young adult stage (day 1 adult) and the old adult stage (day 10 adult). Here, we showed that C. elegans glutamatergic neurons were morphologically intact following low or medium MeHg exposures (0.05 ~ 0.5 µM). The morphological damage of glutamatergic neurons appeared to be pronounced in day 10 adults developmentally exposed to 5 µM MeHg. Behavioral assays also showed an age-dependent latent effect of MeHg. In the nose touch response assay, only day 10 adult worms exhibited a functional decline following prior 5 µM MeHg exposure. Moreover, the disruption of NaCl memory appeared only in day 1 adults following MeHg exposures but not in day 10 adults. The expression of C. elegans homologs of mammalian vesicular glutamate transporter ( eat-4 ) was repressed in day 1 adults, while the glutamate receptor homolog ( glr-1 ) was upregulated in day 10 adults with 5 µM MeHg. In the comparison of age-dependent changes in the insulin-like pathway ( daf-2/age-1/daf-16 ) following MeHg exposures, we showed that the daf-2/age-1/daf-16 pathway was mobilized in day 1 adults but repressed in day 10 adults. Collectively, our data supports a conclusion that MeHg-induced glutamatergic neurotoxicity exhibits an age-dependent pattern, possibly related to the prominent changes in age-dependent modulation in the glutamatergic neurotransmission and metabolic pathways.

Diabetic patients frequently experience neuropathic pain, which currently lacks effective treatments. The mechanisms underlying diabetic neuropathic pain remain unclear. The anterior cingulate cortex (ACC) is well-known to participate in the processing and transformation of pain information derived from internal and external sensory stimulation. Accumulating evidence shows that dysfunction of microglia in the central nervous system contributes to many diseases, including chronic pain and neurodegenerative diseases. In this study, we investigated the role of microglial chemokine CXCL12 and its neuronal receptor CXCR4 in diabetic pain development in a mouse diabetic model established by injection of streptozotocin (STZ). Pain sensitization was assessed by the left hindpaw pain threshold in von Frey filament test. Iba1 + microglia in ACC was examined using combined immunohistochemistry and three-dimensional reconstruction. The activity of glutamatergic neurons in ACC (ACC Glu ) was detected by whole-cell recording in ACC slices from STZ mice, in vivo multi-tetrode electrophysiological and fiber photometric recordings. We showed that microglia in ACC was significantly activated and microglial CXCL12 expression was up-regulated at the 7-th week post-injection, resulting in hyperactivity of ACC Glu and pain sensitization. Pharmacological inhibition of microglia or blockade of CXCR4 in ACC by infusing minocycline or AMD3100 significantly alleviated diabetic pain through preventing ACC Glu hyperactivity in STZ mice. In addition, inhibition of microglia by infusing minocycline markedly decreased STZ-induced upregulation of microglial CXCL12. Together, this study demonstrated that microglia-mediated ACC Glu hyperactivity drives the development of diabetic pain via the CXCL12/CXCR4 signaling, thus revealing viable therapeutic targets for the treatment of diabetic pain.

Neurodegenerative diseases (NDDs) present significant challenges due to limited treatment options, ethical concerns surrounding traditional animal models, and the time-consuming and costly process of using human-induced pluripotent stem cells (iPSCs). We addressed these issues by developing a 3D culture protocol for differentiating SH-SY5Y cells into glutamatergic neurons, enhancing physiological relevance with a 3D microarray culture plate. Our protocol optimized serum concentration and incorporated retinoic acid (RA) to improve differentiation. We analyzed the proportions of N-type and S-type cells, observing that RA in the maturation stage not only reduced cell proliferation but also enhanced the expression of MAP2 and VGLUT1, indicating effective neuronal differentiation. Our approach demonstrates the strong expression of glutamatergic neuron phenotypes in 3D SH-SY5Y neural spheroids, offering a promising tool for high-throughput NDD modeling and advancing drug discovery and therapeutic development. This method overcomes limitations associated with conventional 2D cultures and animal models, providing a more effective platform for NDD research.