Biology subjects

Huh, Y.

Publications and source records attributed to Huh, Y..

7 recordsLinked to original sources

bioRxiv2026

Combination spinal cord stimulation at different frequencies produces sustained pain relief with immune activation

Spinal cord stimulation (SCS) is an established therapy for neuropathic pain, typically delivered at either low (60 Hz) or high (1 kHz) frequencies, with analgesic effects largely dependent on active stimulation. Here, we investigated whether combined-frequency SCS produces sustained analgesia beyond stimulation periods and explored the underlying mechanisms. Using a spared nerve injury (SNI) model in both rats and mice, we applied dual-frequency SCS (60 Hz + 1 kHz). This paradigm produced robust reversal of mechanical allodynia during stimulation and, notably, a progressive and long-lasting analgesic effect that persisted for days to weeks after stimulation cessation. RNA sequencing revealed pronounced immune-related transcriptional changes in the spinal cord, including upregulation of innate immune, pro-resolution, and neutrophil-associated pathways. Functional studies demonstrated that neutrophil depletion attenuated SCS-induced analgesia, whereas intrathecal S100A8 treatment mimicked therapeutic effects via CD69/SOCS3 signaling. These findings identify dual-frequency SCS as a promising strategy to prolong analgesia and highlight a critical role for neuroimmune modulation in sustained pain relief.

neuroscience↗

bioRxiv2024

Distinct Disruptions in CA1 and CA3 Place Cell Function in Alzheimer's Disease Mice

The hippocampus, a critical brain structure for spatial learning and memory, is susceptible to neurodegenerative disorders such as Alzheimers disease (AD). The APPswe/PSEN1dE9 (APP/PS1) transgenic mouse model is widely used to study the pathology of AD. Although previous research has established AD-associated impairments in hippocampal-dependent learning and memory, the neurophysiological mechanisms underlying these cognitive dysfunctions remain less understood. To address this gap, we investigated the activities of place cells in both CA1 and CA3 hippocampal subregions, which have distinct yet complementary computational roles. Behaviorally, APP/PS1 mice demonstrated impaired spatial recognition memory compared to wild-type (WT) mice in the object location test. Physiologically, place cells in APP/PS1 mice showed deterioration in spatial representation compared to WT. Specifically, CA1 place cells exhibited significant reductions in coherence and spatial information, while CA3 place cells displayed a significant reduction in place field size. Both CA1 and CA3 place cells in APP/PS1 mice also showed significant disruptions in their ability to stably encode the same environment. Furthermore, the burst firing properties of these cells were altered to forms correlated with reduced cognition. Additionally, the theta rhythm was significantly attenuated in CA1 place cells of APP/PS1 mice compared to WT. Our results suggest that distinct alteration in the physiological properties of CA1 and CA3 place cells, coupled with disrupted hippocampal theta rhythm in CA1, may collectively contribute to impaired hippocampal-dependent spatial learning and memory in AD.

neuroscience↗

bioRxiv2024

Bidirectional fear modulation by discrete anterior insular circuits in mice

The brains ability to appraise threats and execute appropriate defensive responses is essential for survival in a dynamic environment. Humans studies have implicated the anterior insular cortex (aIC) in subjective fear regulation and its abnormal activity in fear/anxiety disorders. However, the complex aIC connectivity patterns involved in regulating fear remain under investigated. To address this, we recorded single units in the aIC of freely moving male mice that had previously undergone auditory fear conditioning, assessed the effect of optogenetically activating specific aIC output structures in fear, and examined the organization of aIC neurons projecting to the specific structures with retrograde tracing. Single-unit recordings revealed that a balanced number of aIC pyramidal neurons activity either positively or negatively correlated with a conditioned tone-induced freezing (fear) response. Optogenetic manipulations of aIC pyramidal neuronal activity during conditioned tone presentation altered the expression of conditioned freezing. Neural tracing showed that non-overlapping populations of aIC neurons project to the amygdala or the medial thalamus, and the pathway bidirectionally modulated conditioned fear. Specifically, optogenetic stimulation of the aIC-amygdala pathway increased conditioned freezing, while optogenetic stimulation of the aIC-medial thalamus pathway decreased it. Our findings suggest that the balance of freezing-excited and freezing-inhibited neuronal activity in the aIC and the distinct efferent circuits interact collectively to modulate fear behavior.

neuroscience↗

bioRxiv2022

Intrathecal administration of bone marrow stromal cells and TGF-β1 alleviate chemotherapy-induced neuropathic pain in male mice

Chemotherapy-induced peripheral neuropathy (CIPN) is the de facto clinical side effect that limits the administration of anti-cancer treatments. Recently, we reported that intrathecally injected bone marrow stromal cells (BMSCs) reduced nerve trauma-induced neuropathic pain in male mice via TGF-{beta}1 signaling. In this study, we examined sex-dependent pain relief mediated by intrathecally delivered BMSCs and TGF-{beta}1 in paclitaxel (PTX)-induced CIPN. BMSCs were prepared from primary cultures of male or female mice separately. A single intrathecal injection of BMSCs, prepared from male donors, completely prevented the development of PTX-evoked mechanical allodynia in male mice. However, female mice showed no analgesic response to either male or female BMSCs. Additionally, male mice did not demonstrate an analgesic response to BMSCs from female donors. Intrathecal injection of TGF-{beta}1 neutralizing antibody reversed the analgesic action of BMSCs. Interestingly, spinal administration of TGF-{beta}1 reduced mechanical allodynia in male mice but not in female mice. Ex vivo patch-clamp recordings in spinal cord slices revealed that TGF-{beta}1 inhibited PTX-induced synaptic plasticity, i.e. increase in spontaneous excitatory synaptic currents (sEPsCs), in spinal cord neurons from male mice only. Intrathecal TGF-{beta}1 increased the paw withdrawal threshold in von Frey testing in naive mice of males but not females, and the antinociceptive effect of TGF-{beta}1 in males was blocked by orchiectomy-induced androgen deficiency. Together, these findings reveal sex dimorphism in BMSC control of mechanical pain through spinal TGF-{beta}1 signaling.

neuroscience↗

bioRxiv2022

Time-varying hierarchical core voxels disclosed by k-core percolation on dynamic inter-voxel connectivity resting-state fMRI

k-core percolation on the scale-free static brain connectivity revealed hierarchical structure of inter-voxel correlations, which was successfully visualized by hyperbolic disc embedding on resting-state fMRI. In static study, flagplots and brain rendered kmax-core display showed the changes of hierarchical structures of voxels belonging to functional independent components (IC). In this dynamic sliding-window study, temporal progress of hierarchical structure of voxels were investigated in individuals and in sessions of an individual. kmax-core and coreness k values characterizing time-varying core voxels were visualized on animated stacked-histogram/flagplots and animated brain-rendered images. Resting-state fMRI of Human Connectome Project and of Kirby weekly revealed the slow progress and multiple abrupt state transitions of the voxels of coreness k and at the uppermost hierarchy, representing their correlative time-varying mental states in individuals and in sessions. We suggest this characteristic core voxels-IC compositions on dynamic study fingerprint the time-varying resting states of human minds. One Sentence SummaryDynamic state transitions of hierarchical functional inter-voxel connectivity implied time-varying mental states at rest on fMRI

neuroscience↗

bioRxiv2021

Characteristic core voxels in normal individuals revealed by hyperbolic disc embedding and k-core percolation on resting state fMRI

Hyperbolic disc embedding and k-core percolation reveal the core structure of the functional connectivity on resting-state fMRI (rsfMRI). Inter-voxel relations were visualized on embedded hyperbolic discs, and their core composition was traced using k-core percolation. Using 180 normal adults rsfMRI data from the Human Connectome Project database, scale- free intervoxel connectivity represented by IC-voxels composition, while visualized on hyperbolic discs using [Formula] model, showed the expected change of the largest component decreasing its size on k-core percolation eventually yielding the core structures of individuals. This kmax-core voxels-ICs composition revealed such stereotypes of individuals as visual network dominant, default mode network dominant, and distributed patterns. Characteristic core structures of resting-state brain connectivity of normal subjects disclosed the distributed or asymmetric contribution of voxels to the kmax-core, which suggests the hierarchical dominance of certain IC subnetworks characteristic to subgroups of individuals at rest.

neuroscience↗

bioRxiv2020

Central opioid receptors mediate morphine-induced itch and chronic itch

Opioids, such as morphine are mainstay treatments for clinical pain conditions. Itch is a common side effect of opioids, particularly as a result of epidural or intrathecal (i.t.) administration. Recent progress has advanced our understanding of itch circuits in the spinal cord. However, the mechanisms underlying opioid-induced itch are not fully understood, although an interaction between {micro}-opioid receptor (MOR) and gastrin-releasing peptide receptor (GRPR) in spinal GRPR-expressing neurons has been implicated. In this study we investigated the cellular mechanisms of intrathecal (i.t.) opioid-induced itch by conditional deletion of MOR-encoding Oprm1 in distinct populations of interneurons and sensory neurons. We found that i.t. injection of the MOR agonists morphine or DAMGO elicited dose-dependent scratching, but this pruritus was totally abolished in mice with a specific Oprm1 deletion in Vgat+ neurons (Oprm1-Vgat). Loss of MOR in somatostatin+ interneurons and TRPV1+ sensory neurons did not affect morphine-induced itch but impaired morphine-induced antinociception. In situ hybridization revealed Oprm1 expression in 30% of inhibitory and 20% of excitatory interneurons in the spinal dorsal horn. Whole-cell recordings from spinal cord slices showed that DAMGO induced outward currents in 9 out of 19 Vgat+ interneurons examined. Morphine also inhibited action potentials in Vgat+ interneurons and suppressed evoked IPSCs in postsynaptic Vgat- excitatory neurons, suggesting a mechanism of disinhibition by MOR agonists. Notably, morphine-elicited itch was suppressed by i.t. administration of NPY and abolished by spinal ablation of GRPR+ neurons, whereas i.t. GRP-induced itch response remained intact in mice lacking Oprm1-Vgat. Additionally, chronic itch from DNFB-induced allergic contact dermatitis was decreased by Oprm1-Vgat deletion. Finally, naloxone, but not peripherally restricted naloxone methiodide, inhibited chronic itch in the DNFB model and the cutaneous T-cell lymphoma (CTCL) model, indicating a contribution of central MOR signaling to chronic itch. Our findings demonstrate that i.t. morphine elicits itch via acting on MOR on spinal inhibitory interneurons, leading to disinhibition of the spinal itch circuit. Our data also suggest that chronic itch could be effectively treated with CNS-targeted naloxone.

neuroscience↗