Publications by authors named "Keisuke Koga"

Reactive astrocytes play a pivotal role in the pathogenesis of neurological diseases; however, their functional phenotype and the downstream molecules by which they modify disease pathogenesis remain unclear. Here, we genetically increase P2Y receptor (P2Y1R) expression, which is upregulated in reactive astrocytes in several neurological diseases, in astrocytes of male mice to explore its function and the downstream molecule. This astrocyte-specific P2Y1R overexpression causes neuronal hyperexcitability by increasing both astrocytic and neuronal Ca signals.

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The anterior cingulate cortex (ACC) responds to noxious and innocuous sensory inputs, and integrates them to coordinate appropriate behavioral reactions. However, the role of the projections of ACC neurons to subcortical areas and their influence on sensory processing are not fully investigated. Here, we identified that ACC neurons projecting to the contralateral claustrum (ACC) preferentially respond to contralateral mechanical sensory stimulation.

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Article Synopsis
  • Berotralstat is an oral medication used for the prevention of hereditary angioedema in patients aged 12 and older, evaluated in a Phase III trial called APeX-J in Japan.
  • The trial had three parts: the first part compared different doses of berotralstat to a placebo, the second allowed for continuation of treatment, and the third involved all patients receiving berotralstat over an extended period, focusing on safety and effectiveness.
  • Results showed that most patients reported side effects, but they were generally mild, and patients on the 150 mg dose experienced significant reductions in attack rates and improved quality of life.
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Label-free measurement is essential to understand the metabolism of drug molecules introduced into cells. Raman imaging is a powerful method to investigate intracellular drug molecules because it provides in situ label-free observation of introduced molecules. In this study, we propose that Raman imaging can be used not only to observe the intracellular distribution of drug molecules but also to quantitatively visualize the concentration distribution reflecting each organelle in a single living cell using the Raman band of extracellular water as an intensity standard.

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Inhibitory interneurons in the spinal dorsal horn (DH) play a major role in regulating innocuous and noxious information. Reduction in inhibitory synaptic transmission is thought to contribute to the development of touch-evoked pain (allodynia), a common symptom of neuropathic pain. However, it is not fully understood how inhibitory neurons in the DH regulate sensory responses in surrounding neurons and modulate sensory transmission.

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Neuropathic pain, an intractable pain symptom that occurs after nerve damage, is caused by the aberrant excitability of spinal dorsal horn (SDH) neurons. Gabapentinoids, the most commonly used drugs for neuropathic pain, inhibit spinal calcium-mediated neurotransmitter release by binding to αδ-1, a subunit of voltage-gated calcium channels, and alleviate neuropathic pain. However, the exact contribution of αδ-1 expressed in SDH neurons to the altered synaptic transmission and mechanical hypersensitivity following nerve injury is not fully understood.

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Neuropathic pain is a chronic pain condition that occurs after nerve damage; allodynia, which refers to pain caused by generally innocuous stimuli, is a hallmark symptom. Although allodynia is often resistant to analgesics, the antidepressant duloxetine has been used as an effective therapeutic option. Duloxetine increases spinal noradrenaline (NA) levels by inhibiting its transporter at NAergic terminals in the spinal dorsal horn (SDH), which has been proposed to contribute to its pain-relieving effect.

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Mechanical allodynia (pain produced by innocuous stimuli such as touch) is the main symptom of neuropathic pain. Its underlying mechanism remains to be elucidated, but peripheral nerve injury (PNI)-induced malfunction of neuronal circuits in the central nervous system, including the spinal dorsal horn (SDH), is thought to be involved in touch-pain conversion. Here, we found that intra-SDH injection of adeno-associated viral vectors including a prodynorphin promoter (AAV-PdynP) captured a subset of neurons that were mainly located in the superficial laminae, including lamina I, and exhibited mostly inhibitory characteristics.

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An excitatory neuron subset in the spinal dorsal horn (SDH) that expresses gastrin-releasing peptide receptors (GRPR) is critical for pruriceptive transmission. Here, we show that glutamatergic excitatory inputs onto GRPR neurons are facilitated in mouse models of chronic itch. In these models, neuronal pentraxin 2 (NPTX2), an activity-dependent immediate early gene product, is upregulated in the dorsal root ganglion (DRG) neurons.

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It is well known that acute exposure to physical stress produces a transient antinociceptive effect (called stress-induced analgesia [SIA]). One proposed mechanism for SIA involves noradrenaline (NA) in the central nervous system. NA has been reported to activate inhibitory neurons in the spinal dorsal horn (SDH), but its in vivo role in SIA remains unknown.

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In cell transplantation therapy for spinal cord injury (SCI), grafted human induced pluripotent stem cell-derived neural stem/progenitor cells (hiPSC-NS/PCs) mainly differentiate into neurons, forming synapses in a process similar to neurodevelopment. In the developing nervous system, the activity of immature neurons has an important role in constructing and maintaining new synapses. Thus, we investigate how enhancing the activity of transplanted hiPSC-NS/PCs affects both the transplanted cells themselves and the host tissue.

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Our previous study showed the intrinsic ability of descending noradrenergic neurons projecting from the locus coeruleus to the spinal dorsal horn (SDH) to suppress itch-related behaviors. Noradrenaline and α-adrenaline receptor (α-AR) agonist increase inhibitory synaptic inputs onto SDH interneurons expressing gastrin-releasing peptide receptors, which are essential for itch transmission. However, the contribution of α-ARs expressed in SDH inhibitory interneurons to itch-related behavior remains to be determined.

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A cardinal, intractable symptom of neuropathic pain is mechanical allodynia, pain caused by innocuous stimuli via low-threshold mechanoreceptors such as Aβ fibers. However, the mechanism by which Aβ fiber-derived signals are converted to pain remains incompletely understood. Here we identify a subset of inhibitory interneurons in the spinal dorsal horn (SDH) operated by adeno-associated viral vectors incorporating a neuropeptide Y promoter (AAV-NpyP) and show that specific ablation or silencing of AAV-NpyP SDH interneurons converted touch-sensing Aβ fiber-derived signals to morphine-resistant pain-like behavioral responses.

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During rapid eye movement (REM) sleep, anti-gravity muscle tone and bodily movements are mostly absent, because somatic motoneurons are inhibited by descending inhibitory pathways. Recent studies showed that glycine/GABA neurons in the ventromedial medulla (VMM; Gly neurons) play an important role in generating muscle atonia during REM sleep (REM-atonia). However, how these REM-atonia-inducing neurons interconnect with other neuronal populations has been unknown.

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Itch is defined as an unpleasant sensation that provokes a desire to scratch. Our understanding of neuronal circuits for itch information transmission and processing in the spinal dorsal horn (SDH) has progressively advanced following the identification of SDH neuron subsets that are crucial for scratching behavior in models of itch. However, little is known about the control of acute and chronic itch by descending signals from the brain to the SDH.

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Astrocytes are critical regulators of CNS function and are proposed to be heterogeneous in the developing brain and spinal cord. Here we identify a population of astrocytes located in the superficial laminae of the spinal dorsal horn (SDH) in adults that is genetically defined by Hes5. In vivo imaging revealed that noxious stimulation by intraplantar capsaicin injection activated Hes5 SDH astrocytes via α-adrenoceptors (α-ARs) through descending noradrenergic signaling from the locus coeruleus.

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Background: Chronic itch is a highly debilitating symptom among patients with inflammatory skin diseases. Recent studies have revealed that gastrin-releasing peptide (GRP) and its receptor (gastrin-releasing peptide receptor [GRPR]) in the spinal dorsal horn (SDH) play a central role in itch transmission.

Objective: We aimed to investigate whether GRP-GRPR signaling is altered in SDH neurons in a mouse model of chronic itch and to determine the potential mechanisms underlying these alterations.

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Neuropathic pain is caused by peripheral nerve injury (PNI). One hallmark symptom is allodynia (pain caused by normally innocuous stimuli), but its mechanistic underpinning remains elusive. Notably, whether selective stimulation of non-nociceptive primary afferent Aβ fibers indeed evokes neuropathic pain-like sensory and emotional behaviors after PNI is unknown, because of the lack of tools to manipulate Aβ fiber function in awake, freely moving animals.

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Inhibitory interneurons in the spinal dorsal horn (SDH) are crucial for processing somatosensory information originating in the periphery. However, the effects of the acute and selective inactivation of GABAergic SDH interneurons on pain processing are not fully understood. In this study, we used designer receptors exclusively activated by designer drugs (DREADD) technology and vesicular GABA transporter-Cre (Vgat-Cre) mice to selectively express a modified human muscarinic Gi protein-coupled receptor (hM4Di) in Vgat-Cre GABAergic SDH interneurons in the fourth lumbar segment.

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Chronic itch is an intractable symptom of inflammatory skin diseases, such as atopic and contact dermatitis. Recent studies have revealed neuronal pathways selective for itch, but the mechanisms by which itch turns into a pathological chronic state are poorly understood. Using mouse models of atopic and contact dermatitis, we demonstrate a long-term reactive state of astrocytes in the dorsal horn of the spinal segments that corresponds to lesioned, itchy skin.

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Unlabelled: The aim of this study was to investigate the efficacy and safety of combination therapy of interferon and ribavirin for aged patients with chronic hepatitis C.

Methods: This study was conducted at Osaka University Hospital and institutions participating in the Osaka Liver Disease Study Group on 329 patients with chronic hepatitis C receiving interferon and ribavirin combination therapy (group A, under 60 year old, n=199; group B, 60-64 year old, n=64; group C, over 65 year old (mean age, 67.8+/-2.

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Chirality exchange benzannulation of optically active (1S)-aryl(aryl')-2,2-dichlorocyclopropylmethanols (>99% ee) using TiCl4 successfully proceeded to give axially chiral (M)-alpha-arylnaphthalenes with excellent levels of stereo induction (>99% ee). This unique transformation involves the single-step chirality exchange from sp3 central chirality to axial chirality, that is, a type of excellent memory effect.

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We investigated the usefulness of outpatient chemotherapy in 54 cases of non-small cell lung cancer in which outpatient chemotherapy was performed between August 1999 and October 2001. This chemotherapy accounted for 67% of all chemotherapy. Assessment of therapeutic effect revealed a PR in 14 of the 54 cases, and the efficacy rate was 26%.

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