Dermal macrophages control tactile perception under physiological conditions via NGF signaling.

We demonstrated previously that sorting nexin 25 (SNX25) in nerve-associated macrophages plays critical roles in pain sensation by regulating tissue NGF content under both physiological and neuropathic conditions. In the present study, we apply the SNX25-NGF paradigm to tactile perception by showing that Snx25 mice or macrophage-specific Snx25 conditional knock-out (mcKO) mice had weaker responses to tactile stimuli in normal conditions. Snx25 mcKO mice responded poorly to transcutaneous electrical stimuli at a frequency of 5 Hz (C fiber responses), but normally to stimuli at a frequency of 250 Hz (Aδ fiber responses) or of 2000 Hz (Aβ fiber responses).

Hypersensitivity of myelinated A-fibers via toll-like receptor 5 promotes mechanical allodynia in tenascin-X-deficient mice associated with Ehlers-Danlos syndrome.

Deficiency of an extracellular matrix glycoprotein tenascin-X (TNX) leads to a human heritable disorder Ehlers-Danlos syndrome, and TNX-deficient patients complain of chronic joint pain, myalgia, paresthesia, and axonal polyneuropathy. We previously reported that TNX-deficient (Tnxb) mice exhibit mechanical allodynia and hypersensitivity to myelinated A-fibers. Here, we investigated the pain response of Tnxb mice using pharmacological silencing of A-fibers with co-injection of N-(2,6-Dimethylphenylcarbamoylmethyl) triethylammonium bromide (QX-314), a membrane-impermeable lidocaine analog, plus flagellin, a toll-like receptor 5 (TLR5) ligand.

Tenascin-X as a causal gene for classical-like Ehlers-Danlos syndrome.

Tenascin-X (TNX) is an extracellular matrix glycoprotein for which a deficiency results in a recessive form of classical-like Ehlers-Danlos syndrome (clEDS), a heritable connective tissue disorder with hyperextensible skin without atrophic scarring, joint hypermobility, and easy bruising. Notably, patients with clEDS also suffer from not only chronic joint pain and chronic myalgia but also neurological abnormalities such as peripheral paresthesia and axonal polyneuropathy with high frequency. By using TNX-deficient ( ) mice, well-known as a model animal of clEDS, we recently showed that mice exhibit hypersensitivity to chemical stimuli and the development of mechanical allodynia due to the hypersensitization of myelinated A-fibers and activation of the spinal dorsal horn.

TLR4/MD-2 is a receptor for extracellular nucleophosmin 1.

Nucleophosmin 1 (NPM1) primarily localizes to the nucleus and is passively released into the extracellular milieu by necrotic or damaged cells, or is secreted by monocytes and macrophages. Extracellular NPM1 acts as a potent inflammatory stimulator by promoting cytokine production [e.g.

Mechanical allodynia in mice with tenascin-X deficiency associated with Ehlers-Danlos syndrome.

Tenascin-X (TNX) is a member of the extracellular matrix glycoprotein tenascin family, and TNX deficiency leads to Ehlers-Danlos syndrome, a heritable human disorder characterized mostly by skin hyperextensibility, joint hypermobility, and easy bruising. TNX-deficient patients complain of chronic joint pain, myalgia, paresthesia, and axonal polyneuropathy. However, the molecular mechanisms by which TNX deficiency complicates pain are unknown.

Development of a novel photoaffinity probe for labeling nocistatin receptor.

Nocistatin (NST) is a neuropeptide produced from the same precursor protein of opioid peptide nociceptin/orphanin FQ, and it is involved in a broad range of central functions including pain transmission in the nervous system. However, the composition and structure of the receptor(s) for NST remain unclear. Here, we developed NST photoaffinity probe to identify NST receptor.

Intrathecal administration of low-dose nociceptin/orphanin FQ induces allodynia via c-Jun N-terminal kinase and monocyte chemoattractant protein-1.

Pathological chronic pain, which is frequently associated with prolonged tissue damage, inflammation, tumour invasion, and neurodegenerative diseases, gives rise to hyperalgesia and allodynia. We previously reported that intrathecal administration of nociceptin/orphanin FQ (N/OFQ), an endogenous ligand for the orphan opioid receptor-like receptor, in the femtomole range induces touch-evoked allodynia. N/OFQ has been implicated in multiple signalling pathways, such as inhibition of cAMP production and Ca(2+) channels, or activation of K(+) channels and mitogen-activated protein kinase, although the signalling pathways of N/OFQ-induced allodynia remain unclear.

Involvement of NIPSNAP1, a neuropeptide nocistatin-interacting protein, in inflammatory pain.

Background: Chronic pain associated with inflammation is an important clinical problem, and the underlying mechanisms remain poorly understood. 4-Nitrophenylphosphatase domain and nonneuronal SNAP25-like protein homolog (NIPSNAP) 1, an interacting protein with neuropeptide nocistatin, is implicated in the inhibition of tactile pain allodynia. Although nocistatin inhibits some inflammatory pain responses, whether NIPSNAP1 affects inflammatory pain appears to be unclear.

Pain regulation by nocistatin-targeting molecules: G protein-coupled-receptor and nocistatin-interacting protein.

Nociceptin/orphanin FQ (N/OFQ) and nocistatin (NST) are neuropeptides produced from the same precursor protein. N/OFQ is involved in a broad range of central functions including pain, learning, memory, anxiety, and feeding. However, NST has opposite effects on various central functions evoked by N/OFQ.

Nocistatin: milestone of one decade of research.

A neuropeptide nociceptin or orphanin FQ (N/OFQ) is an endogenous ligand for the orphan opioid receptor-like receptor. During studies on the analysis of the precursor of N/OFQ, we identified a novel neuropeptide produced from the same precursor and named it "nocistatin (NST)". Intrathecal (i.

Identification of NIPSNAP1 as a nocistatin-interacting protein involving pain transmission.

4-Nitrophenylphosphatase domain and non-neuronal SNAP25-like protein homolog 1 (NIPSNAP1) is a molecule of physiologically unknown function, although it is predominantly expressed in the brain, spinal cord, liver, and kidney. We identified NIPSNAP1 as a protein that interacts with the neuropeptide nocistatin (NST) from synaptosomal membranes of mouse spinal cord using high-performance affinity latex beads. NST, which is produced from the same precursor protein as an opioid-like neuropeptide nociceptin/orphanin FQ (N/OFQ), has opposite effects on pain transmission evoked by N/OFQ.

A novel role of prostaglandin E2 in neuropathic pain: blockade of microglial migration in the spinal cord.

Neuropathic pain produced by damage to or dysfunction of the nervous system is a common and severely disabling state that affects millions of people worldwide. Recent evidence indicates that activated microglia are key cellular intermediaries in the pathogenesis of neuropathic pain and that ATP serves as the mediator. However, the in vivo mechanism underlying the retention of activated microglia in the injured region has not yet been completely elucidated.

Induction of arginase II mRNA by nitric oxide using an in vitro model of gyrate atrophy of choroid and retina.

Purpose: The authors previously reported ornithine cytotoxicity in ornithine-δ-aminotransferase (OAT)-deficient human retinal pigment epithelial (RPE) cells as an in vitro model of gyrate atrophy of the choroid and retina (GA). Given that RPE cells are severely damaged by arginine combined with ornithine, they investigated the role of arginine metabolism using that in vitro model.

Methods: Human telomerase reverse transcriptase (hTERT)-RPE cells were incubated with ornithine or other agents in the presence of 5-fluoromethylornithine (5-FMO), an OAT-specific inhibitor.

Impairment of CaMKII activation and attenuation of neuropathic pain in mice lacking NR2B phosphorylated at Tyr1472.

Ca(2+) /calmodulin-dependent protein kinase II (CaMKII) is a key mediator of long-term potentiation (LTP), which can be triggered by N-methyl-d-aspartate (NMDA) receptor-mediated Ca(2+) influx. We previously demonstrated that Fyn kinase-mediated phosphorylation of NR2B subunits of NMDA receptors at Tyr1472 in the dorsal horn was involved in a neuropathic pain state even 1 week after nerve injury. Here we show that Y1472F-KI mice with a knock-in mutation of the Tyr1472 site to phenylalanine did not exhibit neuropathic pain induced by L5 spinal nerve transection, whereas they did retain normal nociceptive responses and induction of inflammatory pain.

Characterization of nestin expression in the spinal cord of GFP transgenic mice after peripheral nerve injury.

Many studies have shown that activation and increase in the number of astrocytes and microglia in the spinal cord participate in the initiation and maintenance of neuropathic pain, but little attention has been paid to the responses of neural progenitor cells to peripheral nerve injury. Nestin, a class VI intermediate filament protein, is expressed both in neuronal and glial progenitors as well as in their common precursors; and nestin-positive cells appear in the brain and spinal cord following various forms of damage to these regions. To clarify the responses of neural progenitor cells to nerve injury, we applied L5 spinal nerve transection (L5-SNT) to nestin-promoter GFP (pNestin-GFP) transgenic mice to narrow the target to them.

Involvement of S-nitrosylation of actin in inhibition of neurotransmitter release by nitric oxide.

Background: The role of the diffusible messenger nitric oxide (NO) in the regulation of pain transmission is still a debate of matter, pro-nociceptive and/or anti-nociceptive. S-Nitrosylation, the reversible post-translational modification of selective cysteine residues in proteins, has emerged as an important mechanism by which NO acts as a signaling molecule. The occurrence of S-nitrosylation in the spinal cord and its targets that may modulate pain transmission remain unclarified.

N-ethylmaleimide-sensitive fusion protein (NSF) is involved in central sensitization in the spinal cord through GluR2 subunit composition switch after inflammation.

Central sensitization, similar to long-term potentiation in the hippocampus, refers to the increased synaptic efficacy established in somatosensory neurons in the dorsal horn of the spinal cord following tissue injury or nerve damage. In the course of inflammation, many proteins including glutamate receptors are assumed to be dynamically reorganized in the postsynaptic density (PSD) and involved in persistent pain. Mechanical hyperalgesia induced by intraplantar injection of complete Freund's adjuvant (CFA) was inhibited at 4 h, but not at 24 h, by indomethacin, an inhibitor of prostanoid synthesis.

Involvement of stem cell factor and its receptor tyrosine kinase c-kit in pain regulation.

The c-kit receptor tyrosine kinase is expressed in a subpopulation of small- and medium-sized neurons of the dorsal root ganglia (DRG) and in the superficial layer of the spinal cord. Stem cell factor (SCF), a ligand of the c-kit receptor, induces neurite outgrowth from DRG and supports the survival of c-kit-expressing neurons. To clarify the possible function of the SCF/c-kit receptor system in the adult animal, we investigated the expression of c-kit receptor in the spinal cord and DRG in relation to pain by using H2C7, a newly developed anti-c-kit monoclonal antibody.

Characterization of signaling pathway for the translocation of neuronal nitric oxide synthase to the plasma membrane by PACAP.

In the central nervous system, the activation of neuronal nitric oxide synthase (nNOS) is closely associated with activation of NMDA receptor, and trafficking of nNOS may be a prerequisite for efficient NO production at synapses. We recently demonstrated that pituitary adenylate cyclase activating polypeptide (PACAP) and NMDA synergistically caused the translocation of nNOS to the membrane and stimulated NO production in PC12 (pheochromocytoma) cells. However, the mechanisms responsible for trafficking and activation of nNOS are largely unknown.

Molecular characterization of a novel type of prostamide/prostaglandin F synthase, belonging to the thioredoxin-like superfamily.

Prostaglandin F (PGF) ethanolamide (prostamide F) synthase, which catalyzed the reduction of prostamide H(2) to prostamide F(2alpha), was found in mouse and swine brain. The enzyme was purified from swine brain, and its amino acid sequence was defined. The mouse enzyme consisted of a 603-bp open reading frame coding for a 201-amino acid polypeptide with a molecular weight of 21,669.

Nitric oxide (NO) serves as a retrograde messenger to activate neuronal NO synthase in the spinal cord via NMDA receptors.

We have recently demonstrated that nitric oxide (NO) produced by neuronal NO synthase (nNOS) in the spinal cord is involved in the maintenance of neuropathic pain. To clarify whether NO itself affected nNOS activity in the spinal cord as a retrograde messenger, we examined the involvement of the NO/cGMP signaling pathway in the regulation of nNOS activity by NADPH-diaphorase histochemistry. NO-generating agents NOR3 (t(1/2)=30min) and SNAP (t(1/2)=5h), but not NOR1 (t(1/2)=1.

Interleukin-1 is not essential for expression of inducible NOS in hepatocytes induced by lipopolysaccharide in vivo.

Interleukin (IL)-1 and tumor necrotic factor alpha (TNFalpha) are pivotal in the pathogenesis of endotoxemia. In spite of the in vitro finding that IL-1beta, but not TNFalpha, can induce iNOS mRNA and NO production as a single stimulus in hepatocytes in primary culture, the involvement of IL-1 in iNOS induction in the liver has been less clear in vivo. To address this, we challenged IL-1alpha/beta double-knockout (IL-1alpha/beta(-/-)) and TNFalpha(-/-) mice with lipopolysaccharide (LPS).