Publications by authors named "Shuji Kaneko"

166 Publications

Secreted PLA-III is a possible therapeutic target to treat neuropathic pain.

Biochem Biophys Res Commun 2021 Jul 5;568:167-173. Epub 2021 Jul 5.

Department of Molecular Pharmacology, Kyoto University Graduate School of Pharmaceutical Sciences, Kyoto, 606-8501, Japan; Department of Pharmacology and Therapeutic Innovation, Nagasaki University Institute of Biomedical Sciences, 852-8521, Japan; Laboratory for the Study of Pain, Research Institute for Production Development, Kyoto, 606-0805, Japan. Electronic address:

Lysophosphatidic acid (LPA) plays a critical role in developing and maintaining chronic pain in various animal models. Previous studies have reported that cytosolic and calcium-independent phospholipase A (PLA) is involved in the LPA receptor-mediated amplification of LPA production in the spinal dorsal horn (SDH) after nerve injury, while the involvement of secreted PLA (sPLA) remains unclear. The present study revealed that only sPLA -III among 11 species of PLA showed a significant upregulation of gene expression in the SDH. Intraspinal injection of adeno-associated virus-miRNA targeting sPLA-III prevented hyperalgesia and unique hypoalgesia in mice treated with partial sciatic nerve ligation. In addition, intrathecal treatment with antisense oligodeoxynucleotide or siRNA targeting sPLA-III significantly reversed the established thermal hyperalgesia. In the high-throughput screening of sPLA-III inhibitors from the chemical library, we identified two hit compounds. Through in vitro characterization of PLA inhibitor profiles and in vivo assessment of the anti-hyperalgesic effects of known PLA inhibitors as well as hit compounds, sPLA-III was found to be a novel therapeutic target molecule for the treatment of Neuropathic pain.
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http://dx.doi.org/10.1016/j.bbrc.2021.06.058DOI Listing
July 2021

MrgprB4 in trigeminal neurons expressing TRPA1 modulates unpleasant sensations.

J Pharmacol Sci 2021 Aug 28;146(4):200-205. Epub 2021 Apr 28.

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan.

Gentle touch such as stroking of the skin produces a pleasant feeling, which is detected by a rare subset of sensory neurons that express Mas-related G protein-coupled receptor B4 (MrgprB4) in mice. We examined small populations of MrgprB4-positive neurons in the trigeminal ganglion and the dorsal root ganglion, and most of these were sensitive to transient receptor potential ankyrin 1 (TRPA1) agonist but not TRPV1, TRPM8, or TRPV4 agonists. Deficiency of MrgprB4 did not affect noxious pain or itch behaviors in the hairless plantar and hairy cheek. Although behavior related to acetone-induced cold sensing in the hind paw was not changed, unpleasant sensory behaviors in response to acetone application or sucrose splash to the cheek were significantly enhanced in Mrgprb4-knockout mice as well as in TRPA1-knockout mice. These results suggest that MrgprB4 in the trigeminal neurons produces pleasant sensations in cooperation with TRPA1, rather than noxious or cold sensations. Pleasant sensations may modulate unpleasant sensations on the cheek via MrgprB4.
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http://dx.doi.org/10.1016/j.jphs.2021.04.006DOI Listing
August 2021

Striatal TRPV1 activation by acetaminophen ameliorates dopamine D2 receptor antagonist-induced orofacial dyskinesia.

JCI Insight 2021 May 24;6(10). Epub 2021 May 24.

Department of Molecular Pharmacology, Graduate School and Faculty of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan.

Antipsychotics often cause tardive dyskinesia, an adverse symptom of involuntary hyperkinetic movements. Analysis of the US Food and Drug Administration Adverse Event Reporting System and JMDC insurance claims revealed that acetaminophen prevented the dyskinesia induced by dopamine D2 receptor antagonists. In vivo experiments further showed that a 21-day treatment with haloperidol increased the number of vacuous chewing movements (VCMs) in rats, an effect that was inhibited by oral acetaminophen treatment or intracerebroventricular injection of N-(4-hydroxyphenyl)-arachidonylamide (AM404), an acetaminophen metabolite that acts as an activator of the transient receptor potential vanilloid 1 (TRPV1). In mice, haloperidol-induced VCMs were also mitigated by treatment with AM404 applied to the dorsal striatum, an effect not seen in TRPV1-deficient mice. Acetaminophen prevented the haloperidol-induced decrease in the number of c-Fos+preproenkephalin+ striatal neurons in wild-type mice but not in TRPV1-deficient mice. Finally, chemogenetic stimulation of indirect pathway medium spiny neurons in the dorsal striatum decreased haloperidol-induced VCMs. These results suggest that acetaminophen activates the indirect pathway neurons by activating TRPV1 channels via AM404.
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http://dx.doi.org/10.1172/jci.insight.145632DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8262333PMC
May 2021

NOX1/NADPH Oxidase Promotes Synaptic Facilitation Induced by Repeated D Receptor Stimulation: Involvement in Behavioral Repetition.

J Neurosci 2021 Mar 9;41(12):2780-2794. Epub 2021 Feb 9.

Department of Pharmacology, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan.

Repetitive behavior is a widely observed neuropsychiatric symptom. Abnormal dopaminergic signaling in the striatum is one of the factors associated with behavioral repetition; however, the molecular mechanisms underlying the induction of repetitive behavior remain unclear. Here, we demonstrated that the NOX1 isoform of the superoxide-producing enzyme NADPH oxidase regulated repetitive behavior in mice by facilitating excitatory synaptic inputs in the central striatum (CS). In male C57Bl/6J mice, repeated stimulation of D receptors induced abnormal behavioral repetition and perseverative behavior. deficiency or acute pharmacological inhibition of NOX1 significantly shortened repeated D receptor stimulation-induced repetitive behavior without affecting motor responses to a single D receptor stimulation. Among brain regions, showed enriched expression in the striatum, and repeated dopamine D receptor stimulation further increased expression levels in the CS, but not in the dorsal striatum. Electrophysiological analyses revealed that repeated D receptor stimulation facilitated excitatory inputs in the CS indirect pathway medium spiny neurons (iMSNs), and this effect was suppressed by the genetic deletion or pharmacological inhibition of NOX1. deficiency potentiated protein tyrosine phosphatase activity and attenuated the accumulation of activated Src kinase, which is required for the synaptic potentiation in CS iMSNs. Inhibition of NOX1 or β-arrestin in the CS was sufficient to ameliorate repetitive behavior. Striatal-specific knockdown also ameliorated repetitive and perseverative behavior. Collectively, these results indicate that NOX1 acts as an enhancer of synaptic facilitation in CS iMSNs and plays a key role in the molecular link between abnormal dopamine signaling and behavioral repetition and perseveration. Behavioral repetition is a form of compulsivity, which is one of the core symptoms of psychiatric disorders, such as obsessive-compulsive disorder. Perseveration is also a hallmark of such disorders. Both clinical and animal studies suggest important roles of abnormal dopaminergic signaling and striatal hyperactivity in compulsivity; however, the precise molecular link between them remains unclear. Here, we demonstrated the contribution of NOX1 to behavioral repetition induced by repeated stimulation of D receptors. Repeated stimulation of D receptors upregulated mRNA in a striatal subregion-specific manner. The upregulated NOX1 promoted striatal synaptic facilitation in iMSNs by enhancing phosphorylation signaling. These results provide a novel mechanism for D receptor-mediated excitatory synaptic facilitation and indicate the therapeutic potential of NOX1 inhibition in compulsivity.
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http://dx.doi.org/10.1523/JNEUROSCI.2121-20.2021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8018731PMC
March 2021

The characteristic response of domestic cats to plant iridoids allows them to gain chemical defense against mosquitoes.

Sci Adv 2021 Jan 20;7(4). Epub 2021 Jan 20.

Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan.

Domestic cats and other felids rub their faces and heads against catnip () and silver vine () and roll on the ground as a characteristic response. While this response is well known, its biological function and underlying mechanism remain undetermined. Here, we uncover the neurophysiological mechanism and functional outcome of this feline response. We found that the iridoid nepetalactol is the major component of silver vine that elicits this potent response in cats and other felids. Nepetalactol increased plasma β-endorphin levels in cats, while pharmacological inhibition of μ-opioid receptors suppressed the classic rubbing response. Rubbing behavior transfers nepetalactol onto the faces and heads of respondents where it repels the mosquito, Thus, self-anointing behavior helps to protect cats against mosquito bites. The characteristic response of cats to nepetalactol via the μ-opioid system provides an important example of chemical pest defense using plant metabolites in nonhuman mammals.
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http://dx.doi.org/10.1126/sciadv.abd9135DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7817105PMC
January 2021

Transient Receptor Potential Melastatin 3 Is Functionally Expressed in Oligodendrocyte Precursor Cells and Is Upregulated in Ischemic Demyelinated Lesions.

Biol Pharm Bull 2021 ;44(2):181-187

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University.

Oligodendrocyte precursor cells (OPCs) are glial cells that differentiate into oligodendrocytes and myelinate axons. The number of OPCs is reportedly increased in brain lesions in some demyelinating diseases and during ischemia; however, these cells also secrete cytokines and elicit both protective and deleterious effects in response to brain injury. The mechanism regulating the behaviors of OPCs in physiological and pathological conditions must be elucidated to control these cells and to treat demyelinating diseases. Here, we focused on transient receptor potential melastatin 3 (TRPM3), a Ca-permeable channel that is activated by the neurosteroid pregnenolone sulfate (PS) and body temperature. Trpm3/Pdgfra OPCs were detected in the cerebral cortex (CTX) and corpus callosum (CC) of P4 and adult rats by in situ hybridization. Trpm3 expression was detected in primary cultured rat OPCs and was increased by treatment with tumor necrosis factor α (TNFα). Application of PS (30-100 µM) increased the Ca concentration in OPCs and this effect was inhibited by co-treatment with the TRP channel blocker Gd (100 µM) or the TRPM3 inhibitor isosakuranetin (10 µM). Stimulation of TRPM3 with PS (50 µM) did not affect the differentiation or migration of OPCs. The number of Trpm3 OPCs was markedly increased in demyelinated lesions in an endothelin-1 (ET-1)-induced ischemic rat model. In conclusion, TRPM3 is functionally expressed in OPCs in vivo and in vitro and is upregulated in inflammatory conditions such as ischemic insults and TNFα treatment, implying that TRPM3 is involved in the regulation of specific behaviors of OPCs in pathological conditions.
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http://dx.doi.org/10.1248/bpb.b20-00510DOI Listing
January 2021

Prediction of pharmacological activities from chemical structures with graph convolutional neural networks.

Sci Rep 2021 01 12;11(1):525. Epub 2021 Jan 12.

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.

Many therapeutic drugs are compounds that can be represented by simple chemical structures, which contain important determinants of affinity at the site of action. Recently, graph convolutional neural network (GCN) models have exhibited excellent results in classifying the activity of such compounds. For models that make quantitative predictions of activity, more complex information has been utilized, such as the three-dimensional structures of compounds and the amino acid sequences of their respective target proteins. As another approach, we hypothesized that if sufficient experimental data were available and there were enough nodes in hidden layers, a simple compound representation would quantitatively predict activity with satisfactory accuracy. In this study, we report that GCN models constructed solely from the two-dimensional structural information of compounds demonstrated a high degree of activity predictability against 127 diverse targets from the ChEMBL database. Using the information entropy as a metric, we also show that the structural diversity had less effect on the prediction performance. Finally, we report that virtual screening using the constructed model identified a new serotonin transporter inhibitor with activity comparable to that of a marketed drug in vitro and exhibited antidepressant effects in behavioural studies.
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http://dx.doi.org/10.1038/s41598-020-80113-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7803991PMC
January 2021

Allodynia by Splenocytes From Mice With Acid-Induced Fibromyalgia-Like Generalized Pain and Its Sexual Dimorphic Regulation by Brain Microglia.

Front Neurosci 2020 23;14:600166. Epub 2020 Dec 23.

Department of Pharmacology and Therapeutic Innovation, Nagasaki University Institute of Biomedical Sciences, Nagasaki, Japan.

Fibromyalgia (FM), a disease of unknown etiology characterized by chronic generalized pain, is partly recapitulated in an animal model induced by repeated acid saline injections into the gastrocnemius muscle. Here, we attempted to investigate the sex difference in pain hypersensitivity (mechanical allodynia and hypersensitivity to electrical stimulation) in the repeated acid saline-induced FM-like generalized pain (AcGP) model. The first unilateral acid injection into gastrocnemius muscle at day 0/D0 and second injection at D5 (post day 0, P0) induced transient and long-lasting mechanical allodynia, respectively, on both sides of male and female mice. The pretreatment with gonadectomy did not affect the first injection-induced allodynia in both sexes, but gradually reversed the second injection-induced allodynia in male but not female mice. Moreover, the AcGP in male mice was abolished by intracerebroventricular minocycline treatments during D4-P4 or P5-P11, but not by early treatments during D0-D5 in male but not female mice, suggesting that brain microglia are required for AcGP in late-onset and sex-dependent manners. We also found that the intravenous treatments of splenocytes derived from male but not female mice treated with AcGP caused allodynia in naive mice. In addition, the purified CD4 T cells derived from splenocytes of acid-treated male mice retained the ability to cause allodynia in naive mice. These findings suggest that FM-like AcGP has multiple sexual dimorphic mechanisms.
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http://dx.doi.org/10.3389/fnins.2020.600166DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7785978PMC
December 2020

Lacking transient receptor potential melastatin 2 attenuates lipopolysaccharide-induced bladder inflammation and its associated hypersensitivity in mice.

Int J Urol 2021 Jan 7;28(1):107-114. Epub 2020 Oct 7.

Department of Continence Medicine, The University of Tokyo Graduate School of Medicine, Tokyo, Japan.

Objective: To study the role of transient receptor potential melastatin 2 in bladder function and inflammation-associated hypersensitivity.

Methods: We evaluated physiological function of the bladder and intravesical lipopolysaccharide-induced inflammatory nociceptive responses in female wild-type and transient receptor potential melastatin 2-knockout mice. In vivo frequency/volume and decerebrated unanesthetized cystometry measurements, as well as in vitro detrusor strip functional studies, were carried out to evaluate bladder function. Mice received intravesical lipopolysaccharide (2.0 mg/mL) or saline instillation to evaluate responses to bladder inflammation. Voiding and bladder pain-like behaviors, cystometry measurements and histological evaluation were carried out before and after intravesical lipopolysaccharide instillation.

Results: Few phenotypic differences in in vivo and in vitro physiological function were found between the two genotypes. Comparison of measurements taken before and 24-48 h after intravesical lipopolysaccharide instillation showed that voiding parameters did not change in transient receptor potential melastatin 2-knockout mice, whereas an increased voiding frequency was observed in wild-type mice. At 24 h after intravesical lipopolysaccharide instillation, the numbers of bladder pain-like behaviors and of infiltrated inflammatory cells in the bladder submucosal layer were significantly increased, and the voided volume and the intercontraction interval were significantly decreased on cystometry measurements in wild-type mice compared with those in both transient receptor potential melastatin 2-knockout mice and in wild-type mice treated with saline instillation.

Conclusions: Although the physiological roles of transient receptor potential melastatin 2 channels in the bladder might be limited, inflammation and associated hypersensitivity of the bladder caused by intravesical lipopolysaccharide instillation are attenuated in transient receptor potential melastatin 2-knockout mice, suggesting pathophysiological roles of transient receptor potential melastatin 2 channels in these processes.
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http://dx.doi.org/10.1111/iju.14389DOI Listing
January 2021

Synthesis and biological evaluation of radioiodinated 3-phenylcoumarin derivatives targeting myelin in multiple sclerosis.

Bioorg Med Chem Lett 2020 12 22;30(24):127562. Epub 2020 Sep 22.

Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan. Electronic address:

Myelin is a lipid multilayer involved in the rate of nerve transmission, and its loss is a pathological feature of multiple sclerosis in brains. Since in vivo imaging of myelin may be useful for drug development, early diagnosis, and monitoring the disease stage, we designed, synthesized, and evaluated eight novel radioiodinated 3-phenylcoumarin derivatives as imaging probes targeting myelin. In the biodistribution study using normal mice, all compounds displayed sufficient brain uptake, ranging from 2.5 to 5.0% ID/g, at 2 min postinjection. On ex vivo autoradiography, [I]18 and [I]21, which have a dimethylamino group, showed high binding affinity for myelin in the normal mouse brain. In addition, the radioactivity accumulation of [I]21 in the white matter of the spinal cord in the experimental autoimmune encephalomyelitis mice was lower than that in naive mice. These results suggest that [I]21 shows potential as a single photon emission computed tomography probe targeting myelin.
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http://dx.doi.org/10.1016/j.bmcl.2020.127562DOI Listing
December 2020

Transient receptor potential vanilloid 4 agonist GSK1016790A improves neurological outcomes after intracerebral hemorrhage in mice.

Biochem Biophys Res Commun 2020 08 16;529(3):590-595. Epub 2020 Jul 16.

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Japan.

Intracerebral hemorrhage (ICH) is one of the most severe subtypes of stroke with high morbidity and mortality. Although a lot of drug discovery studies have been conducted, the drugs with satisfactory therapeutic effects for motor paralysis after ICH have yet to reach clinical application. Transient receptor potential vanilloid 4 (TRPV4), a Ca-permeable cation channel and activated by hypoosmolarity and warm temperature, is expressed in various cell types. The present study investigated whether TRPV4 would participate in the brain damage in a mouse model of ICH. ICH was induced by intrastriatal treatment of collagenase. Administration of GSK1016790A, a selective TRPV4 agonist, attenuated neurological and motor deficits. The inhibitory effects of the TRPV4 agonist in collagenase-injected WT mice were completely disappeared in TRPV4-KO mice. The TRPV4 agonist did not alter brain injury volume and brain edema at 1 and 3 days after ICH induction. The TRPV4 agonist did not show any differences with respect to the increased number of Iba1-positive microglia/macrophages, GFAP-positive astrocytes, and Gr1-positive neutrophils at 1 and 3 days after ICH induction. Quantitative RT-PCR experiments revealed that the TRPV4 agonist significantly upregulated the expression level of c-fos, a marker of neuronal activity, while the agonist gave no effects on the expression level of cytokines/chemokines at 1 day after ICH induction, These results suggest that stimulation of TRPV4 would ameliorate ICH-induced brain injury, presumably by increased neuronal activity and TRPV4 provides a novel therapeutic target for the treatment for ICH.
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http://dx.doi.org/10.1016/j.bbrc.2020.06.103DOI Listing
August 2020

Protective effects of Nrf2-ARE activator on dopaminergic neuronal loss in Parkinson disease model mice: Possible involvement of heme oxygenase-1.

Neurosci Lett 2020 09 23;736:135268. Epub 2020 Jul 23.

Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan; Department of Applied Pharmacology, Graduate School of Medical and Pharmaceutical Science, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan. Electronic address:

Parkinson disease (PD) is a neurodegenerative disorder characterized by a selective loss of dopaminergic neurons in the substantia nigra, and oxidative stress is thought to contribute to this pathogenesis. The nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway, which induces the production of antioxidant enzymes, is thereby a potential target for therapeutics to reduce neurodegeneration in PD. Previously, we identified TPNA10168 from a chemical library as an activator of the Nrf2-ARE pathway, and the present study examined the effects of TPNA10168 on an in vivo PD model. Subcutaneous administration of TPNA10168 was associated with inhibited dopaminergic neuronal loss and behavioral impairment in 6-hydroxydopamine-induced PD model mice. Heme oxygenase-1 (HO-1) is an antioxidant enzyme expressed downstream of the Nrf2-ARE signaling pathway, and we observed that HO-1 protein levels were upregulated by TPNA10168 in the mouse brain. These results suggest that TPNA10168 inhibits dopaminergic neuronal death in PD model mice, and that upregulation of HO-1 might participate in this effect.
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http://dx.doi.org/10.1016/j.neulet.2020.135268DOI Listing
September 2020

The Role of Dorsal Raphe Serotonin Neurons in the Balance between Reward and Aversion.

Int J Mol Sci 2020 Mar 21;21(6). Epub 2020 Mar 21.

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan.

Background: Reward processing is fundamental for animals to survive and reproduce. Many studies have shown the importance of dorsal raphe nucleus (DRN) serotonin (5-HT) neurons in this process, but the strongly correlative link between the activity of DRN 5-HT neurons and rewarding/aversive potency is under debate. Our primary objective was to reveal this link using two different strategies to transduce DRN 5-HT neurons.

Methods: For transduction of 5-HT neurons in wildtype mice, adeno-associated virus (AAV) bearing the mouse tryptophan hydroxylase 2 (TPH2) gene promoter was used. For transduction in Tph2-tTA transgenic mice, AAVs bearing the tTA-dependent TetO enhancer were used. To manipulate the activity of 5-HT neurons, optogenetic actuators (CheRiff, eArchT) were expressed by AAVs. For measurement of rewarding/aversive potency, we performed a nose-poke self-stimulation test and conditioned place preference (CPP) test.

Results: We found that stimulation of DRN 5-HT neurons and their projections to the ventral tegmental area (VTA) increased the number of nose-pokes in self-stimulation test and CPP scores in both targeting methods. Concomitantly, CPP scores were decreased by inhibition of DRN 5-HT neurons and their projections to VTA.

Conclusion: Our findings indicate that the activity of DRN 5-HT neurons projecting to the VTA is a key modulator of balance between reward and aversion.
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http://dx.doi.org/10.3390/ijms21062160DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7139834PMC
March 2020

Drug Repositioning and Target Finding Based on Clinical Evidence.

Biol Pharm Bull 2020 ;43(3):362-365

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University.

Recent pharmacological studies have been developed based on finding new disease-related genes, accompanied by the production of gene-manipulated disease model animals and high-affinity ligands for the target proteins. However, the emergence of this gene-based strategy in drug development has led to the rapid depletion of drug target molecules. To overcome this, we have attempted to utilize clinical big data to explore a novel and unexpected hypothesis of drug-drug interaction that would lead to drug repositioning. Here, we introduce our data-driven approach in which adverse event self-reports are statistically analyzed and compared in order to find and validate new drug targets. The hypotheses provided by such a data-driven approach will likely impact the style of future drug development and pharmaceutical study.
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http://dx.doi.org/10.1248/bpb.b19-00929DOI Listing
September 2020

Acute restraint stress augments the rewarding memory of cocaine through activation of α adrenoceptors in the medial prefrontal cortex of mice.

Neuropharmacology 2020 04 6;166:107968. Epub 2020 Feb 6.

Laboratory of Molecular Pharmacology, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, 920-1192, Japan. Electronic address:

Stress augments the rewarding memory of cocaine, which plays a critical role in inducing cocaine craving. However, the neurobiological mechanisms underlying the enhancing effect of stress remain unclear. Here, we show that noradrenaline (NA) transmission in the medial prefrontal cortex (mPFC) mediates stress-induced enhancement of cocaine craving. When mice were exposed to acute restraint stress immediately before the posttest session of the cocaine-induced conditioned place preference (CPP) paradigm, the CPP score was significantly higher than that in non-stressed mice. Because extracellular NA levels have been reported to be increased in the mPFC during stress exposure, we assessed the effects of NA on mPFC layer 5 pyramidal cell activity. Whole-cell recordings revealed that NA application induces depolarization and a concomitant increase in spontaneous excitatory postsynaptic currents (sEPSCs). The NA effects were inhibited by terazosin, but not by yohimbine or timolol, and the sEPSC increase was not observed in the presence of tetrodotoxin, suggesting the involvement of postsynaptic α, but not α or β, adrenoceptors in the NA effects. Additionally, intra-mPFC injection of terazosin before stress exposure attenuated the stress-induced increase in cocaine CPP. Intra-mPFC injection of phenylephrine, an α adrenoceptor agonist, before the posttest session without stress exposure significantly enhanced cocaine CPP. Furthermore, chemogenetic suppression of mPFC pyramidal cells with inhibitory DREADD (designer receptors exclusively activated by designer drugs) also suppressed the stress-induced CPP enhancement. These findings suggest that the stress-induced increase in NA transmission activates mPFC pyramidal cells via α adrenoceptor stimulation, leading to enhancement of cocaine craving-related behavior.
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http://dx.doi.org/10.1016/j.neuropharm.2020.107968DOI Listing
April 2020

Myelin Oligodendrocyte Glycoprotein 35-55 (MOG 35-55)-induced Experimental Autoimmune Encephalomyelitis: A Model of Chronic Multiple Sclerosis.

Bio Protoc 2019 Dec 20;9(24):e3453. Epub 2019 Dec 20.

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.

Multiple sclerosis (MS) is the common demyelinating disease of human central nervous system. Among mouse models available to study MS, including the cuprizone application and lysolecithin-injection models, experimental autoimmune encephalomyelitis (EAE) model is widely used so that chronic EAE model of C57BL/6J can reflect the autoimmune pathogenesis of MS well. Here we introduce the EAE model based on C57BL/6J mice, which is generated by injection of myelin oligodendrocyte glycoprotein 35-55 (MOG 35-55) as an antigen. After immunization with complete Freund's adjuvant, clinical signs and changes in body weight are observed one or two weeks later. The EAE model will continue to be useful for development of therapeutics for MS.
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http://dx.doi.org/10.21769/BioProtoc.3453DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7853963PMC
December 2019

Identification of neuron-type specific promoters in monkey genome and their functional validation in mice.

Biochem Biophys Res Commun 2019 10 23;518(4):619-624. Epub 2019 Aug 23.

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan. Electronic address:

Viral gene delivery is one of the most versatile techniques for elucidating the mechanisms underlying brain dysfunction, such as neuropsychiatric disorders. Due to the complexity of the brain, expression of genetic tools, such as channelrhodopsin and calcium sensors, often has to be restricted to a specified cell type within a circuit implicated in these disorders. Only a handful of promoters targeting neuronal subtypes are currently used for viral gene delivery. Here, we isolated conserved promoter regions of several subtype-specific genes from the macaque genome and investigated their functionality in the mouse brain when used within lentiviral vectors (LVVs). Immunohistochemical analysis revealed that transgene expression induced by the promoter sequences for somatostatin (SST), cholecystokinin (CCK), parvalbumin (PV), serotonin transporter (SERT), vesicular acetylcholine transporter (vAChT), substance P (SP) and proenkephalin (PENK) was largely colocalized with specific markers for the targeted neuronal populations. Moreover, by combining these results with in silico predictions of transcription factor binding to the isolated sequences, we identified transcription factors possibly underlying cell-type specificity. These findings lay a foundation for the expansion of the current toolbox of promoters suitable for elucidating these neuronal phenotypes.
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http://dx.doi.org/10.1016/j.bbrc.2019.08.101DOI Listing
October 2019

CRISPR/Cas9-mediated in vivo gene editing reveals that neuronal 5-HT receptors in the dorsal raphe nucleus contribute to body temperature regulation in mice.

Brain Res 2019 09 10;1719:243-252. Epub 2019 Jun 10.

Department of Neuropharmacology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15 W7 Kita-ku, Sapporo 060-8638, Japan.

Serotonin (5-HT) in the central nervous system regulates a variety of biological functions, from the basic homeostatic control to higher brain functions, by acting on fourteen known receptor subtypes. However, it is still usually unclear which receptor subtype is responsible for a specific function due to the lack of highly selective ligands for most of these receptors. Although 5-HT receptor knockout mice are useful, the brain-wide distribution of various receptors makes it difficult to dissect receptor functions in specific and brain regions and cell types. Recent advances in CRISPR/Cas9-mediated in vivo genome editing technology may overcome this problem. In this study, we constructed a viral vector expressing a single guide (sg)RNA targeting Htr1a (sgHtr1a) and Cre recombinase under the control of a neuron-specific promoter. Injection of the viral vector into the dorsal raphe nucleus (DRN) of Cre-dependent Cas9 knock-in mice induced Cre-dependent Cas9 expression mainly in DRN serotonin and GABA neurons. Mismatch cleavage assay and Sanger sequencing showed insertion or deletion formation at the target site. 5-HT receptor agonist-induced hypothermia was attenuated and antidepressant effect of a selective serotonin reuptake inhibitor (SSRI) was enhanced by microinjection of the viral vector expressing sgHtr1a into the DRN of Cre-dependent Cas9 knock-in mice. These results suggest that this in vivo CRISPR/Cas9-mediated 5-HT receptor gene knockout strategy provides a reliable and low-cost method for elucidating 5-HT receptor functions in specific cell types and brain regions. Further, we demonstrate that the neuronal 5-HT receptor in the DRN regulates body temperature and antidepressant effect of SSRI.
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http://dx.doi.org/10.1016/j.brainres.2019.06.009DOI Listing
September 2019

Depletion of microglia ameliorates white matter injury and cognitive impairment in a mouse chronic cerebral hypoperfusion model.

Biochem Biophys Res Commun 2019 07 13;514(4):1040-1044. Epub 2019 May 13.

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.

Microglia are immune cells in the central nervous system (CNS) and essential for homeostasis that are important for both neuroprotection and neurotoxicity, and are activated in a variety of CNS diseases. Microglia aggravate cognitive impairment induced by chronic cerebral hypoperfusion, but their precise roles under these conditions remain unknown. Here, we used PLX3397, a colony-stimulating factor 1 receptor inhibitor, to deplete microglia in mice with chronic cerebral hypoperfusion induced by bilateral common carotid artery stenosis (BCAS). Cognitive impairment induced 28 days after BCAS was significantly improved in mice fed a diet containing PLX3397. In PLX3397-fed mice, microglia were depleted and white matter injury induced by BCAS was suppressed. In addition, the expression of proinflammatory cytokines, interleukin 6 and tumor necrosis factor alpha, was suppressed in PLX3397-fed mice. Taken together, these findings suggest that microglia play destructive roles in the development of cognitive impairment and white matter injury induced by chronic cerebral hypoperfusion. Thus, microglia represent a potential therapeutic target for chronic cerebral hypoperfusion-related diseases.
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http://dx.doi.org/10.1016/j.bbrc.2019.05.055DOI Listing
July 2019

Pathophysiological Role of TRPM2 in Age-Related Cognitive Impairment in Mice.

Neuroscience 2019 06 15;408:204-213. Epub 2019 Apr 15.

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan.

Aging causes various functional changes, including cognitive impairment and inflammatory responses in the brain. Transient receptor potential melastatin 2 (TRPM2), a Ca-permeable channel expressed abundantly in immune cells, exacerbates inflammatory responses. Previously, we reported that TRPM2 on resident microglia plays a critical role in exacerbating inflammation, white matter injury, and cognitive impairment during chronic cerebral hypoperfusion; however, the physiological or pathophysiological role of TRPM2 during age-associated inflammatory responses remains unclear. Therefore, we examined the effects of TRPM2 deletion in young (2-3 months) and older (12-24 months) mice. Compared with young wild-type (WT) mice, middle-aged (12-16 months) WT mice showed working and cognitive memory dysfunction and aged (20-24 months) WT mice exhibited impaired spatial memory. However, these characteristics were not seen in TRPM2 knockout (TRPM2-KO) mice. Consistent with the finding of cognitive impairment, aged WT mice exhibited white matter injury and hippocampal damage and an increase in the number of Iba1-positive cells and amounts of pro-inflammatory cytokines in the brain; these characteristics were not seen in TRPM2-KO mice. These findings suggest that TRPM2 plays a critical role in exacerbating inflammatory responses and cognitive dysfunction during aging.
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http://dx.doi.org/10.1016/j.neuroscience.2019.04.012DOI Listing
June 2019

Effects of the synthetic cannabinoid 5F-AMB on anxiety and recognition memory in mice.

Psychopharmacology (Berl) 2019 Jul 13;236(7):2235-2242. Epub 2019 Mar 13.

Laboratory of Molecular Pharmacology, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, 920-1192, Japan.

Rationale: N-[[1-(5-fluoropentyl)-1H-indazol-3-yl]carbonyl]-L-valine methyl ester (5F-AMB) is a synthetic cannabinoid that has been distributed recently. Although inhalation of 5F-AMB produces adverse effects, such as impaired memory and disturbed consciousness, in humans, the psychopharmacological effects of 5F-AMB in rodents have not been investigated.

Objectives: We first examined the effects of intraperitoneal and intracerebroventricular injections of 5F-AMB on anxiety-like behavior and locomotor activity in the open field (OF) test and recognition memory in the novel object recognition test (NOR) in C57BL/6J mice. We also examined whether a cannabinoid 1 (CB1) receptor antagonist AM251 blocks the effects of 5F-AMB. We next examined the effects of 5F-AMB infusion into the medial prefrontal cortex (mPFC), a brain region associated with anxiety and memory, on these tests.

Results: Intraperitoneal injection of 5F-AMB (0.3 mg/kg) dramatically decreased locomotor activity in the OF, and this effect was partially reversed by AM251 (3 mg/kg). Intracerebroventricular infusion of 5F-AMB (10 nmol) produced an anxiolytic effect in the OF and impaired acquisition, but not retrieval, of recognition memory in the NOR, and these effects were blocked by co-infusion of AM251 (1.8 nmol). Bilateral intra-mPFC infusion of 5F-AMB (10 pmol/side) similarly produced impaired recognition memory acquisition, but no anxiolytic effect.

Conclusions: The results demonstrate that centrally administered 5F-AMB produces anxiolytic effect and impaired recognition memory acquisition via activation of CB1 receptors, while systemic 5F-AMB severely impaired locomotor activity. The mPFC is involved in 5F-AMB-induced impairment of recognition memory acquisition. However, other brain region(s) may contribute to the 5F-AMB-induced anxiolytic effect.
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http://dx.doi.org/10.1007/s00213-019-05222-2DOI Listing
July 2019

An Adenosine A Receptor Antagonist Improves Multiple Symptoms of Repeated Quinpirole-Induced Psychosis.

eNeuro 2019 Jan-Feb;6(1). Epub 2019 Feb 27.

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.

Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder characterized by the repeated rise of concerns (obsessions) and repetitive unwanted behavior (compulsions). Although selective serotonin reuptake inhibitors (SSRIs) is the first-choice drug, response rates to SSRI treatment vary between symptom dimensions. In this study, to find a therapeutic target for SSRI-resilient OCD symptoms, we evaluated treatment responses of quinpirole (QNP) sensitization-induced OCD-related behaviors in mice. SSRI administration rescued the cognitive inflexibility, as well as hyperactivity in the lateral orbitofrontal cortex (lOFC), while no improvement was observed for the repetitive behavior. D receptor signaling in the central striatum (CS) was involved in SSRI-resistant repetitive behavior. An adenosine A antagonist, istradefylline, which rescued abnormal excitatory synaptic function in the CS indirect pathway medium spiny neurons (MSNs) of sensitized mice, alleviated both of the QNP-induced abnormal behaviors with only short-term administration. These results provide a new insight into therapeutic strategies for SSRI-resistant OCD symptoms and indicate the potential of A antagonists as a rapid-acting anti-OCD drug.
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http://dx.doi.org/10.1523/ENEURO.0366-18.2019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6397953PMC
April 2019

Glutamatergic neurons in the medial prefrontal cortex mediate the formation and retrieval of cocaine-associated memories in mice.

Addict Biol 2020 01 7;25(1):e12723. Epub 2019 Feb 7.

Laboratory of Molecular Pharmacology, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.

In drug addiction, environmental stimuli previously associated with cocaine use readily elicit cocaine-associated memories, which persist long after abstinence and trigger cocaine craving and consumption. Although previous studies suggest that the medial prefrontal cortex (mPFC) is involved in the expression of cocaine-addictive behaviors, it remains unclear whether excitatory and inhibitory neurons in the mPFC are causally related to the formation and retrieval of cocaine-associated memories. To address this issue, we used the designer receptors exclusively activated by designer drugs (DREADD) technology combined with a cocaine-induced conditioned place preference (CPP) paradigm. We suppressed mPFC neuronal activity in a cell-type- and timing-dependent manner. C57BL/6J wild-type mice received bilateral intra-mPFC infusion of an adeno-associated virus (AAV) expressing inhibitory DREADD (hM4Di) under the control of CaMKII promotor to selectively suppress mPFC pyramidal neurons. GAD67-Cre mice received bilateral intra-mPFC infusion of a Cre-dependent AAV expressing hM4Di to specifically silence GABAergic neurons. Chemogenetic suppression of mPFC pyramidal neurons significantly attenuated both the acquisition and expression of cocaine CPP, while suppression of mPFC GABAergic neurons affected neither the acquisition nor expression of cocaine CPP. Moreover, chemogenetic inhibition of mPFC glutamatergic neurons did not affect the acquisition and expression of lithium chloride-induced conditioned place aversion. These results suggest that the activation of glutamatergic, but not GABAergic, neurons in the mPFC mediates both the formation and retrieval of cocaine-associated memories.
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http://dx.doi.org/10.1111/adb.12723DOI Listing
January 2020

The Crotalaria juncea metal transporter CjNRAMP1 has a high Fe uptake activity, even in an environment with high Cd contamination.

Int J Phytoremediation 2018 17;20(14):1427-1437. Epub 2019 Jan 17.

a Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere , Kyoto University , Kyoto , Japan.

Large quantities of Fe and Cd accumulate in the leaves of the metal-accumulating leguminous plant, Crotalaria juncea. A member of the metal transporter NRAMP family was cloned from C. juncea. The amino acid sequence of this clone, designated CjNRAMP1, was similar to the sequence of Arabidopsis AtNRAMP1, which is involved in Fe and Cd transport. Organ-specific analysis showed that CjNRAMP1 mRNA was expressed mainly in the leaves of C. juncea plants, as well as in stems and roots. Use of green fluorescent protein fused to CjNRAMP1 suggested its localization to the plasma membranes of plant cells. Complementation experiments using yeast strains with impaired metal transport systems showed that CjNRAMP1 transported both Fe and Cd in an inward direction within the cells. Transgenic Arabidopsis plants overexpressing CjNRAMP1 showed high tolerance to Cd, with Cd translocation from roots to leaves being substantially greater in transgenic than in wild-type plants. Overexpression of CjNRAMP1 resulted in a greater accumulation of Fe in shoots and roots, suggesting that CjNRAMP1 recognizes Fe and Cd as substrates and that the high Cd tolerance of CjNRAMP1 is due to its strong Fe uptake activity, even in the presence of high Cd concentrations in the rhizosphere.
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http://dx.doi.org/10.1080/15226514.2018.1501333DOI Listing
September 2019

Manipulation of dorsal raphe serotonergic neurons modulates active coping to inescapable stress and anxiety-related behaviors in mice and rats.

Neuropsychopharmacology 2019 03 30;44(4):721-732. Epub 2018 Oct 30.

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.

Major depression and anxiety disorders are a social and economic burden worldwide. Serotonergic signaling has been implicated in the pathophysiology of these disorders and thus has been a crucial target for pharmacotherapy. However, the precise mechanisms underlying these disorders are still unclear. Here, we used species-optimized lentiviral vectors that were capable of efficient and specific transduction of serotonergic neurons in mice and rats for elucidation of serotonergic roles in anxiety-like behaviors and active coping behavior in both species. Immunohistochemical analyses revealed that lentiviral vectors with an upstream sequence of tryptophan hydroxylase 2 gene efficiently transduced serotonergic neurons with a specificity of approximately 95% in both mice and rats. Electrophysiological recordings showed that these lentiviral vectors induced sufficient expression of optogenetic tools for precise control of serotonergic neurons. Using these vectors, we demonstrate that acute activation of serotonergic neurons in the dorsal raphe nucleus increases active coping with inescapable stress in rats and mice in a time-locked manner, and that acute inhibition of these neurons increases anxiety-like behaviors specifically in rats. These findings further our understanding of the pathophysiological role of dorsal raphe serotonergic neurons in different species and the role of these neurons as therapeutic targets in major depression and anxiety disorders.
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http://dx.doi.org/10.1038/s41386-018-0254-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6372597PMC
March 2019

Attenuated lipopolysaccharide-induced inflammatory bladder hypersensitivity in mice deficient of transient receptor potential ankilin1.

Sci Rep 2018 10 23;8(1):15622. Epub 2018 Oct 23.

Department of Continence Medicine, The University of Tokyo Graduate School of Medicine, Tokyo, Japan.

Transient receptor potential ankyrin 1 (TRPA1) channel expressed by urothelial cells and bladder sensory nerve fibers might act as a bladder mechanosensor and nociceptive transducer. To disclose the role of TRPA1 in bladder function and inflammation-associated hypersensitivity, we evaluated in vitro and in vivo bladder function and inflammatory mechanosensory and nociceptive responses to intravesical lipopolysaccharide (LPS)-instillation in wild type (WT) and TRPA1-knock out (KO) mice. At baseline before treatment, no significant differences were observed in frequency volume variables, in vitro detrusor contractility, and cystometric parameters between the two groups in either sex. LPS-instillation significantly increased voiding frequency and decreased mean voided volume at 24-48 hours after instillation in WT but not in TRPA1-KO mice. LPS-instillation also significantly increased the number of pain-like behavior at 24 hours after instillation in WT mice, but not in TRPA1-KO mice. Cystometry 24 hours after LPS-instillation revealed shorter inter-contraction intervals in the WT mice compared with TRPA1-KO mice. In contrast, inflammatory cell infiltration in the bladder suburothelial layer was not significantly different between the two groups. These results indicate that TRPA1 channels are involved in bladder mechanosensory and nociceptive hypersensitivity accompanied with inflammation but not in physiological bladder function or development of bladder inflammation.
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http://dx.doi.org/10.1038/s41598-018-33967-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6199359PMC
October 2018

TRPM2 confers susceptibility to social stress but is essential for behavioral flexibility.

Brain Res 2019 02 28;1704:68-77. Epub 2018 Sep 28.

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan.

Transient receptor potential melastatin 2 (TRPM2) is a Ca-permeable, nonselective cation channel and a member of the TRP channel superfamily that acts as a sensor of intracellular redox states. TRPM2 is widely distributed in many tissues and highly expressed in the brain, but the physiological roles of TRPM2 in the central nervous system remain unclear. In this study, TRPM2-deficient mice were examined in a series of behavioral tests. TRPM2-deficient mice did not significantly differ from wild-type littermates in muscle strength, light/dark transition test, rotarod, elevated plus maze, social interaction, prepulse inhibition, Y-maze, forced swim test, cued and contextual fear conditioning, and tail suspension test. In the Barnes circular maze, TRPM2-deficient mice learned the fixed escape box position at similar extent to wild-type littermates, suggesting normal reference memory. However, performance of the first reversal trial and probe test were significantly impaired in TRPM2-deficient mice. In the T-maze delayed alternation task, TRPM2 deficiency significantly reduced choice accuracy. These results indicate that TRPM2-deficient mice shows behavioral inflexibility. Meanwhile, social avoidance induced by repeated social defeat stress was significantly attenuated in TRPM2-deficient mice, suggesting that TRPM2 deficiency confers stress resiliency. Our findings indicate that TRPM2 plays an essential role in maintaining behavioral flexibility but it increases susceptibility to stress.
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http://dx.doi.org/10.1016/j.brainres.2018.09.031DOI Listing
February 2019

TRPM2 Exacerbates Central Nervous System Inflammation in Experimental Autoimmune Encephalomyelitis by Increasing Production of CXCL2 Chemokines.

J Neurosci 2018 09 10;38(39):8484-8495. Epub 2018 Sep 10.

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.

Multiple sclerosis (MS) is a chronic inflammatory disorder of the CNS characterized by demyelination and axonal injury. Current therapies that mainly target lymphocytes do not fully meet clinical need due to the risk of severe side effects and lack of efficacy against progressive MS. Evidence suggests that MS is associated with CNS inflammation, although the underlying molecular mechanism is poorly understood. Transient receptor potential melastatin 2 (TRPM2), a Ca-permeable nonselective cation channel, is expressed at high levels in the brain and by immune cells, including monocyte lineage cells. Here, we show that TRPM2 plays a pathological role in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. Knockout (KO) or pharmacological inhibition of TRPM2 inhibited progression of EAE and TRPM2-KO mice showed lower activation of Iba1-immunopositive monocyte lineage cells and neutrophil infiltration of the CNS than WT mice. Moreover, CXCL2 production in TRPM2-KO mice was significantly reduced at day 14, although the severity of EAE was the same as that in WT mice at that time point. In addition, we used BM chimeric mice to show that TRPM2 expressed by CNS-infiltrating macrophages contributes to progression of EAE. Because CXCL2 induces migration of neutrophils, these results indicate that reduced expression of CXCL2 in the CNS suppresses neutrophil infiltration and slows progression of EAE in TRPM2-KO mice. Together, the results suggest that TRPM2 plays an important role in progression of EAE pathology and shed light on its putative role as a therapeutic target for MS. Current therapies for multiple sclerosis (MS), which mainly target lymphocytes, carry the risk of severe side effects and lack efficacy against the progressive form of the disease. Here, we found that the transient receptor potential melastatin 2 (TRPM2) channel, which is abundantly expressed in CNS-infiltrating macrophages, plays a crucial role in development of experimental autoimmune encephalomyelitis (EAE), an animal model of MS. EAE progression was suppressed by Knockout (KO) or pharmacological inhibition of TRPM2; this was attributed to a reduction in CXCL2 chemokine production by CNS-infiltrating macrophages in TRPM2-KO mice, resulting in suppression of neutrophil infiltration into the CNS. These results reveal an important role of TRPM2 in the pathogenesis of EAE and shed light on its potential as a therapeutic target.
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http://dx.doi.org/10.1523/JNEUROSCI.2203-17.2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6596171PMC
September 2018

The impact of mouse strain-specific spatial and temporal immune responses on the progression of neuropathic pain.

Brain Behav Immun 2018 11 29;74:121-132. Epub 2018 Aug 29.

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan.

The present study was designed to investigate the correlation between the spatial and temporal aspects of immune responses and genetic heterogeneity in the progression of peripheral neuropathic pain. To address this issue, we first screened four inbred mouse strains (C57BL/6J, C3H/He, DBA/2, and A/J mice) to identify high- and low-responder strains to mechanical hypersensitivity induced by partial sciatic nerve ligation (pSNL). Among these strains, the C57BL/6J strain showed the highest vulnerability to pSNL-induced mechanical hypersensitivity, whereas the C3H/HeSlc strain was most resistant. C3H/HeSlc mice exhibited a significant increase in CD206-immunoreactivity (anti-inflammatory macrophages) in the dorsal root ganglia (DRG) at 3 and 7 days, and lower Iba1-immunoreactivity (microglia) in the spinal cord from 3 to 14 days after pSNL than C57BL/6J mice. These phenomena might be associated with a decrease in the production of inflammatory factors (interleukin-1β, interleukin-6, and CX3CL1) in the DRG and the poor responsiveness of spinal microglia (i.e. microglial production of IL1β, CCL2, and TNFα) against CX3CL1 in C3H/HeSlc mice. Behavioral experiments using bone marrow (BM) chimeric mice derived by crossing C3H/HeSlc and C57BL/6J strains showed that the strength of mechanical hypersensitivity 3 days following pSNL was inversely correlated with the increase in the ratio of anti-inflammatory/pro-inflammatory DRG macrophages, which was based on the BM-derived hematopoietic cells from donor mice. By contrast, the intensity of Iba1-immunoreactivity (microglia) in the spinal cord was dependent on the phenotypes of recipient mice, but not affected by the phenotypes of BM-derived donor hematopoietic cells. These findings suggest that the strain-specific aspects of DRG macrophages and spinal microglia might be related to the early and late phases of pSNL-induced mechanical hypersensitivity, respectively. This study presents a greater understanding of the differences in neuropathic pain among genetically heterogeneous inbred mouse strains, and provides further insights into the spatial and temporal roles of the immune system in the pathogenesis of neuropathic pain.
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http://dx.doi.org/10.1016/j.bbi.2018.08.013DOI Listing
November 2018

Physiological and Pathophysiological Roles of Transient Receptor Potential Channels in Microglia-Related CNS Inflammatory Diseases.

Biol Pharm Bull 2018 ;41(8):1152-1157

Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University.

Central nervous system (CNS) inflammation is a potential therapeutic target for neurodegenerative diseases. In recent years, a number of studies have focused on the links between neurodegenerative diseases and CNS glial cells, especially microglia. Microglia are the main resident immune cells in the CNS and represent approximately 10-15% of all CNS cells. Microglia play an important role in maintaining brain homeostasis at rest by surveying the environment, and engulfing apoptotic cells and debris in the healthy brain. However, under certain pathological conditions, microglia can generate neurotoxic factors, such as pro-inflammatory cytokines and molecules like nitric oxide (NO), which lead to CNS inflammatory diseases. In this review, we discuss the evidence that regulation of microglial ion channels may modulate CNS inflammation and subsequent tissue damage in neurological disorders. In particular, we discuss the role of transient receptor potential (TRP) channels in microglia in both acute and chronic inflammatory conditions, and describe the physiological and pathophysiological roles of TRP channels in CNS inflammatory pathways. Additionally, we describe the benefits of stimulation/inhibition of TRP channels in animal models of microglia-related CNS inflammatory diseases.
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http://dx.doi.org/10.1248/bpb.b18-00319DOI Listing
October 2018
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