Publications (61)178.02 Total impact
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Article: Identification of 5-HT receptor subtypes enhancing inhibitory transmission in the rat spinal dorsal horn in vitro.
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ABSTRACT: BACKGROUND: 5-hydroxytryptamine (5-HT) is one of the major neurotransmitters widely distributed in the CNS. Several 5-HT receptor subtypes have been identified in the spinal dorsal horn which act on both pre- and postsynaptic sites of excitatory and inhibitory neurons. However, the receptor subtypes and sites of actions as well as underlying mechanism are not clarified rigorously. Several electrophysiological studies have been performed to investigate the effects of 5-HT on excitatory transmission in substantia gelatinosa (SG) of the spinal cord. In the present study, to understand the effects of 5-HT on the inhibitory synaptic transmission and to identify receptor subtypes, the blind whole cell recordings were performed from SG neurons of rat spinal cord slices. RESULTS: Bath applied 5-HT (50 microM) increased the frequency but not amplitudes of spontaneous inhibitory postsynaptic currents (sIPSCs) in 58% of neurons, and both amplitude and frequency in 23 % of neurons. The frequencies of GABAergic and glycinergic mIPSCs were both enhanced. TTX (0.5 microM) had no effect on the increasing frequency, while the enhancement of amplitude of IPSCs was eliminated. Evoked-IPSCs (eIPSCs) induced by focal stimulation near the recording neurons in the presence of CNQX and APV were enhanced in both amplitude by 5-HT. In the presence of Ba2+ (1 mM), a potassium channel blocker, 5-HT had no effect on both frequency and amplitude. A 5-HT2Areceptor agonist, TCB-2 mimicked the 5-HT effect, and ketanserin, an antagonist of 5-HT2A receptor, inhibited the effect of 5-HT partially and TCB-2 almost completely. A 5-HT2C receptor agonist WAY 161503 mimicked the 5-HT effect and this effect was blocked by a 5-HT2C receptor antagonist, N-desmethylclozapine. The amplitude of sIPSCs were unaffected by both agonists. A 5-HT3 receptor agonist mCPBG enhanced both amplitude and frequency of sIPSCs. This effect was blocked by a 5-HT3 receptor antagonist ICS-205,930. The perfusion of 5-HT2B receptor agonist had no effect on sIPSCs. CONCLUSIONS: Our results demonstrated that 5-HT modulated the inhibitory transmission in SG by the activation of 5-HT2A and 5-HT2C receptors subtypes located predominantly at inhibitory interneuron terminals, and 5-HT3 receptors located at inhibitory interneuron terminals and soma-dendrites, consequently enhanced both frequency and amplitude.Molecular Pain 08/2012; 8(1):58. · 3.53 Impact Factor -
Article: Anti-hyperalgesic effects of calcitonin on neuropathic pain interacting with its peripheral receptors.
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ABSTRACT: BACKGROUND: The polypeptide hormone calcitonin is clinically well known for its ability to relieve neuropathic pain such as spinal canal stenosis, diabetic neuropathy and complex regional pain syndrome. Mechanisms for its analgesic effect, however, remain unclear. Here we investigated the mechanism of anti-hyperalgesic action of calcitonin in a neuropathic pain model in rats. RESULTS: Subcutaneous injection of elcatonin, a synthetic derivative of eel calcitonin, relieved hyperalgesia induced by chronic constriction injury (CCI). Real-time reverse transcriptase-polymerase chain reaction analysis revealed that the CCI provoked the upregulation of tetrodotoxin (TTX)-sensitive Nav.1.3 mRNA and downregulation of TTX-resistant Nav1.8 and Nav1.9 mRNA on the ipsilateral dorsal root ganglion (DRG), which would consequently increase the excitability of peripheral nerves. These changes were reversed by elcatonin. In addition, the gene expression of the calcitonin receptor and binding site of 125I-calcitonin was increased at the constricted peripheral nerve tissue but not at the DRG. The anti-hyperalgesic effect and normalization of sodium channel mRNA by elcatonin was parallel to the change of the calcitonin receptor expression. Elcatonin, however, did not affect the sensitivity of nociception or gene expression of sodium channel, while it suppressed calcitonin receptor mRNA under normal conditions. CONCLUSIONS: These results suggest that the anti-hyperalgesic action of calcitonin on CCI rats could be attributable to the normalization of the sodium channel expression, which might be exerted by an unknown signal produced at the peripheral nerve tissue but not by DRG neurons through the activation of the calcitonin receptor. Calcitonin signals were silent in the normal condition and nerve injury may be one of triggers for conversion of a silent to an active signal.Molecular Pain 06/2012; 8(1):42. · 3.53 Impact Factor -
Article: GABA(A) receptor-mediated presynaptic inhibition on glutamatergic transmission.
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ABSTRACT: We investigated the functional roles of presynaptic GABA(A) receptors on excitatory nerve terminals in contributing to spontaneous and action potential-evoked glutamatergic transmission to rat hippocampal CA3 pyramidal neurons. Single CA3 neurons were mechanically isolated with adherent nerve terminals, namely the 'synaptic bouton preparation', and spontaneous glutamatergic excitatory synaptic potentials (sEPSCs) and EPSCs evoked by focal electrical stimuli of a single presynaptic glutamatergic boutons (eEPSCs) were recorded using conventional whole-cell patch recordings. Selective activation of presynaptic GABA(A) receptors on these excitatory nerve terminals by muscimol, markedly facilitated sEPSCs frequency but inhibited eEPSC amplitude. The facilitation of sEPSC frequency was completely occluded by GABA(A) receptor-Cl⁻ channel blockers bicuculline or penicillin (PN). PN itself concentration-dependently inhibited the GABA(A) receptor response induced by bath application of muscimol, but had no effect on the glutamate receptor response. In addition, pretreatment with a blocker of the Na(+), K(+), 2Cl⁻ co-transporter type 1 (NKCC-1), bumetanide, prevented the muscimol-induced inhibition of eEPSCs. The results indicate that activation of presynaptic GABA(A) receptors directly depolarizes glutamatergic excitatory nerve terminals and thereby differentially modulates sEPSCs and eEPSCs.Brain research bulletin 10/2010; 84(1):22-30. · 2.18 Impact Factor -
Article: Enhancement of GABAergic tonic currents by midazolam and noradrenaline in rat substantia gelatinosa neurons in vitro.
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ABSTRACT: Substantia gelatinosa of the spinal dorsal horn is crucial for transmission and modification of noxious stimuli. Previous studies have demonstrated that intrathecal midazolam, a benzodiazepine agonist, enhanced perioperative analgesia. Not only synaptic but also extrasynaptic inhibitory currents contribute to modification of noxious stimuli. Thus, the effects of midazolam on extrasynaptic gamma-aminobutyric acid (GABA) type A receptors in substantia gelatinosa neurons and interaction with noradrenaline, a transmitter of the descending inhibitory systems, were investigated. Using whole cell patch-clamp technique in the adult rat spinal cord slices, extrasynaptic GABAergic currents were recorded in substantia gelatinosa neurons in the presence of gabazine (1 microm), which blocked synaptic GABAergic currents, and then midazolam (5 microm) and noradrenaline (20 microm) were applied. Bath application of midazolam induced tonic outward currents in the presence of gabazine. Although the decay time of synaptic current was prolonged, neither frequency nor amplitude was affected by midazolam. In contrast, the application of noradrenaline markedly increased both frequency and amplitude of synaptic currents with a slight enhancement of tonic currents. Coapplication of noradrenaline and midazolam markedly increased tonic currents, and the increase was much greater than the sum of currents induced by noradrenaline and midazolam. Midazolam had much larger effects on extrasynaptic GABA type A receptors than the synaptic receptors, suggesting a role of the enhancement of GABAergic extrasynaptic currents in the midazolam-induced analgesia. Because noradrenaline is shown to increase extrasynaptic GABA concentration, simultaneous administration of noradrenaline and midazolam may enhance the increased GABA action by midazolam, thereby resulting in an increase in tonic extrasynaptic currents.Anesthesiology 08/2010; 113(2):429-37. · 5.36 Impact Factor -
Article: Comparative study on the actions of toxin extracts from two different puffer fishes on I(Na) and respiratory N-M transmission in the rat.
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ABSTRACT: We performed a comparative study on the effects of toxin extracts prepared from muscle and liver of two different puffer fishes on voltage dependent sodium current (I(Na)), and compared the results with that of tetrodotoxin (TTX). The amount of toxin contained in the muscle or liver expressed as an amount of equipotent TTX differed in the two species (0.11-57.98 microg TTX/g tissue). In addition, we observed the effects of TTX or toxin extracts on the twitch contraction evoked by direct muscle stimulation of the rat hemidiaphragm or indirect phrenic nerve stimulations, in an attempt to understand the mechanisms involved in the transmission failure in the respiratory muscles, due to the ingestion of TTX bearing puffers, and found that TTX or toxin extracts preferentially affect motor nerve rather than muscle.Fukuoka igaku zasshi = Hukuoka acta medica 08/2010; 101(8):173-81. -
Article: Responsiveness of C neurons in rat dorsal root ganglion to 5-hydroxytryptamine-induced pruritic stimuli in vivo.
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ABSTRACT: Itching is a common symptom in dermatologic diseases and causes restless scratching of the skin, which aggravates the condition. The mechanism of the itch sensation, however, is enigmatic. The present study included behavioral tests and electrophysiological recordings from rat dorsal root ganglion (DRG) neurons in vivo to analyze the response to pruritic stimuli induced by topical application of 5-hydroxytryptamine (5-HT) to the skin. Topically applied 5-HT to the rostral back evoked scratching, whereas application of the vehicle did not. Following subcutaneous injection of the opioid receptor antagonist naloxone, the number of scratches decreased, suggesting that the scratching was preferentially mediated by itch but not pain sensation. To elucidate the firing properties of DRG neurons in response to topically applied 5-HT, intracellular recordings were made from DRG neurons in vivo. None of the Abeta and Adelta neurons responded to 5-HT; in contrast, 25 of 91 C neurons (27%) exhibited repetitive firing in response to 5-HT, which could be classified into two firing patterns: one was a transient type, characterized by low firing frequency that decreased within 5 min; the other was a long-lasting type, having high firing frequency that continued increasing after 5 min. The time course of the firing pattern of long-lasting C neurons was comparable to the scratching behavior. Intriguingly, the long-lasting-type neurons had a significantly smaller fast afterhyperpolarization than that of the 5-HT-insensitive neurons. These observations suggest that the long-lasting-firing C neurons in rat DRG sensitive to 5-HT are responsible for conveying pruritic information to the spinal cord.Journal of Neurophysiology 07/2010; 104(1):271-9. · 3.32 Impact Factor -
Article: TRPA1-expressing primary afferents synapse with a morphologically identified subclass of substantia gelatinosa neurons in the adult rat spinal cord.
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ABSTRACT: The TRPA1 channel has been proposed to be a molecular transducer of cold and inflammatory nociceptive signals. It is expressed on a subset of small primary afferent neurons both in the peripheral terminals, where it serves as a sensor, and on the central nerve endings in the dorsal horn. The substantia gelatinosa (SG) of the spinal cord is a key site for integration of noxious inputs. The SG neurons are morphologically and functionally heterogeneous and the precise synaptic circuits of the SG are poorly understood. We examined how activation of TRPA1 channels affects synaptic transmission onto SG neurons using whole-cell patch-clamp recordings and morphological analyses in adult rat spinal cord slices. Cinnamaldehyde (TRPA1 agonist) elicited a barrage of excitatory postsynaptic currents (EPSCs) in a subset of the SG neurons that responded to allyl isothiocyanate (less specific TRPA1 agonist) and capsaicin (TRPV1 agonist). Cinnamaldehyde evoked EPSCs in vertical and radial but not islet or central SG cells. Notably, cinnamaldehyde produced no change in inhibitory postsynaptic currents and nor did it produce direct postsynaptic effects. In the presence of tetrodotoxin, cinnamaldehyde increased the frequency but not amplitude of miniature EPSCs. Intriguingly, cinnamaldehyde had a selective inhibitory action on monosynaptic C- (but not Adelta-) fiber-evoked EPSCs. These results indicate that activation of spinal TRPA1 presynaptically facilitates miniature excitatory synaptic transmission from primary afferents onto vertical and radial cells to initiate action potentials. The presence of TRPA1 channels on the central terminals raises the possibility of bidirectional modulatory action in morphologically identified subclasses of SG neurons.European Journal of Neuroscience 05/2010; 31(11):1960-73. · 3.63 Impact Factor -
Article: Bone cancer induces a unique central sensitization through synaptic changes in a wide area of the spinal cord.
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ABSTRACT: Chronic bone cancer pain is thought to be partly due to central sensitization. Although murine models of bone cancer pain revealed significant neurochemical changes in the spinal cord, it is not known whether this produces functional alterations in spinal sensory synaptic transmission. In this study, we examined excitatory synaptic responses evoked in substantia gelatinosa (SG, lamina II) neurons in spinal cord slices of adult mice bearing bone cancer, using whole-cell voltage-clamp recording techniques. Mice at 14 to 21 days after sarcoma implantation into the femur exhibited hyperalgesia to mechanical stimuli applied to the skin of the ipsilateral hind paw, as well as showing spontaneous and movement evoked pain-related behaviors. SG neurons exhibited spontaneous excitatory postsynaptic currents (EPSCs). The amplitudes of spontaneous EPSCs were significantly larger in cancer-bearing than control mice without any changes in passive membrane properties of SG neurons. In the presence of TTX, the amplitude of miniature EPSCs in SG neurons was increased in cancer-bearing mice and this was observed for cells sampled across a wide range of lumbar segmental levels. Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor- and N-methyl-D-aspartate (NMDA) receptor-mediated EPSCs evoked by focal stimulation were also enhanced in cancer-bearing mice. Dorsal root stimulation elicited mono- and/or polysynaptic EPSCs that were caused by the activation of Adelta and/or C afferent fibers in SG neurons from both groups of animals. The number of cells receiving monosynaptic inputs from Adelta and C fibers was not different between the two groups. However, the amplitude of the monosynaptic C fiber-evoked EPSCs and the number of SG neurons receiving polysynaptic inputs from Adelta and C fibers were increased in cancer-bearing mice. These results show that spinal synaptic transmission mediated through Adelta and C fibers is enhanced in the SG across a wide area of lumbar levels following sarcoma implantation in the femur. This widespread spinal sensitization may be one of the underlying mechanisms for the development of chronic bone cancer pain.Molecular Pain 01/2010; 6:38. · 3.53 Impact Factor -
Article: Organization of intralaminar and translaminar neuronal connectivity in the superficial spinal dorsal horn.
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ABSTRACT: The spinal dorsal horn exhibits a high degree of intrinsic connectivity that is critical to its role in the processing of nociceptive information. To examine the spatial organization of this intrinsic connectivity, we used laser-scanning photostimulation in parasagittal and transverse slices of lumbar spinal cord to stimulate presynaptic neurons by glutamate uncaging, and mapped the location of sites that provide excitatory and inhibitory synaptic input to neurons of the superficial laminae. Excitatory interneuronal connectivity within lamina II exhibited a pronounced sagittal orientation, in keeping with the somatotopic organization present in the pattern of primary afferent projections. Excitatory inputs to all classes of lamina II neurons arose from a wider rostrocaudal area than inhibitory inputs, whereas both excitatory and inhibitory input zones were restricted mediolaterally. Lamina I-II neurons exhibited cell type-specific patterns in the laminar distribution of their excitatory inputs that were related to their dorsoventral dendritic expanse. All cell types received excitatory input predominantly from positions ventral to that of their soma, but in lamina I neurons and lamina II vertical cells this ventral displacement of the excitatory input zone was greater than in the other cell types, resulting in a more pronounced translaminar input pattern. A previously unknown excitatory input to the superficial dorsal horn from lamina III-IV was identified in a subset of the vertical cell population. These results reveal a specific three-dimensional organization in the local patterns of excitatory and inhibitory connectivity that has implications for the processing of information related to both somatotopy and sensory modality.Journal of Neuroscience 05/2009; 29(16):5088-99. · 7.11 Impact Factor -
Article: Actions of propofol on substantia gelatinosa neurones in rat spinal cord revealed by in vitro and in vivo patch-clamp recordings.
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ABSTRACT: Propofol, an intravenous general anaesthetic, exerts anaesthetic actions through interaction with gamma-aminobutyric acid type A (GABA(A)) receptors in the supraspinal nervous system. However, whether propofol has any significant effects on synaptic transmission at the spinal level and whether it exhibits antinociceptive action is still not fully clarified. Spontaneous activity and stimulus-evoked responses of substantia gelatinosa (SG) neurones to noxious pinch stimuli were recorded using spontaneously breathing rats under propofol anaesthesia using in vivo whole-cell patch-clamp techniques. Precise actions of propofol on GABAergic and glycinergic inhibitory postsynaptic currents (IPSCs) as well as excitatory postsynaptic currents (EPSCs) in SG neurones were also analyzed in spinal cord slice preparations. At clinical doses (5 mg/kg), propofol reversibly depressed action potentials elicited by noxious mechanical stimuli applied to the skin in the majority (6/8) of SG neurons recorded under in vivo conditions. This depression may have been caused by interactions of propofol with GABA(A) receptors, as decay time of GABAergic sIPSCs was prolonged after propofol injection (128 +/- 11% of control, n = 5) with minimal effect on EPSCs. Although prolongation of IPSCs in vivo was reversible, IPSCs were progressively prolonged even after washout of propofol when the effect was tested using spinal cord slices. Propofol had a mild depressant effect on Adelta- and C-afferent-mediated EPSCs. We conclude that systemic bolus injection of propofol reversibly depressed nociceptive transmission, at least in part, by enhancing postsynaptic GABA(A) receptor-mediated responses in the SG.European Journal of Neuroscience 03/2009; 29(3):518-28. · 3.63 Impact Factor -
Article: Cytokine-induced suppression of medial preoptic neurons: mechanisms and neuroimmunomodulatory effects.
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ABSTRACT: We have shown that the medial preoptic area (MPO) in the hypothalamus is a major site where interferon (IFN)-alpha acts to induce suppression of splenic natural killer (NK) cell activity through an activation of sympathetic nervous system (SNS) in rats. Here, we discuss the hypothalamic mechanisms of the cytokine action using in vivo and in vitro preparations in rats. Lesion of the MPO activated the SNS and suppressed splenic NK cell activity in anesthetized rats, suggesting that the MPO had an inhibitory influence on nerve activity. Since both IFN-alpha and interleukin (IL)-1beta are known to suppress MPO neuron activity, it is suggested that the suppression/loss of the MPO caused by cytokine actions/lesions disinhibits the hypothalamic-sympathetic pathway, thereby resulting in an increase in the splenic SNS and reduction of NK activity. To explore the cellular mechanisms of the suppression of MPO neurons, the effects of Prostaglandin E2 (PGE2), one of the major mediators of cytokine action in the brain, on the glutamate-induced membrane currents were examined using the perforated patch-clamp method in mechanically dissociated MPO neurons. Patch-clamp analysis revealed that PGE2 potentiated the Ca2+-dependent K+ current (KCa) stimulated by Ca2+ entry through N-methyl-D-aspartate channels. We suggest that the cytokine-induced decrease in the firing rates of MPO neurons may be a result of an increase in interspike intervals caused by PGE(2)-induced enhancement of KCa in the presence of glutamatergic inputs.Annals of the New York Academy of Sciences 03/2009; 1153:76-81. · 3.15 Impact Factor -
Article: Cytokine‐induced Suppression of Medial Preoptic Neurons
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ABSTRACT: We have shown that the medial preoptic area (MPO) in the hypothalamus is a major site where interferon (IFN)-α acts to induce suppression of splenic natural killer (NK) cell activity through an activation of sympathetic nervous system (SNS) in rats. Here, we discuss the hypothalamic mechanisms of the cytokine action using in vivo and in vitro preparations in rats. Lesion of the MPO activated the SNS and suppressed splenic NK cell activity in anesthetized rats, suggesting that the MPO had an inhibitory influence on nerve activity. Since both IFN-α and interleukin (IL)-1β are known to suppress MPO neuron activity, it is suggested that the suppression/loss of the MPO caused by cytokine actions/lesions disinhibits the hypothalamic–sympathetic pathway, thereby resulting in an increase in the splenic SNS and reduction of NK activity. To explore the cellular mechanisms of the suppression of MPO neurons, the effects of Prostaglandin E2 (PGE2), one of the major mediators of cytokine action in the brain, on the glutamate-induced membrane currents were examined using the perforated patch-clamp method in mechanically dissociated MPO neurons. Patch-clamp analysis revealed that PGE2 potentiated the Ca2+-dependent K+ current (KCa) stimulated by Ca2+ entry through N-methyl-D-aspartate channels. We suggest that the cytokine-induced decrease in the firing rates of MPO neurons may be a result of an increase in interspike intervals caused by PGE2-induced enhancement of KCa in the presence of glutamatergic inputs.Annals of the New York Academy of Sciences 01/2009; 1153(1):76 - 81. · 3.15 Impact Factor -
Article: Neurotropin reverses paclitaxel-induced neuropathy without affecting anti-tumour efficacy.
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ABSTRACT: Paclitaxel is a commonly used anticancer drug, but it frequently causes peripheral neuropathy. Neurotropin, a non-protein extract from inflamed rabbit skin inoculated with vaccinia virus, has been used to treat various chronic painful conditions. In the present study, we investigated the effect of neurotropin on the paclitaxel-induced neuropathy in rats. Repeated administration of paclitaxel induced mechanical allodynia, cold hyperalgesia, and motor dysfunction. These neuropathies were mostly reversed by the repeated administration of neurotropin. Furthermore, neurotropin ameliorated the paclitaxel-induced axonal degeneration in cultured PC12 and rat dorsal root ganglion cells, and in rat sciatic nerve. In addition, neurotropin did not affect the microtubule aggregation or anti-tumour effect induced by paclitaxel in the tumour cell lines or tumour cells-implanted mice. These results suggest that neurotropin reverses the paclitaxel-induced neuropathy without affecting anti-tumour activity of paclitaxel, and therefore may be useful for the paclitaxel-induced neuropathy in clinical settings.European journal of cancer (Oxford, England: 1990) 12/2008; 45(1):154-63. · 4.12 Impact Factor -
Article: N-ethylmaleimide-sensitive fusion protein (NSF) is involved in central sensitization in the spinal cord through GluR2 subunit composition switch after inflammation.
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ABSTRACT: 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. To elucidate the nature of the molecule(s) involved in the late phase of inflammatory pain, we analysed the PSD fraction prepared from the lumbar spinal cord of rats before and 24 h after CFA injection by conducting two-dimensional differential gel electrophoresis. N-ethylmaleimide-sensitive fusion protein (NSF) was identified as a downregulated protein in the PSD by MALDI-TOF MS and immunoblotting. Concomitant with the decrease in NSF, GluR2 and GluR3 were decreased and GluR1 was conversely increased in the PSD fraction 24 h after CFA injection. In vivo patch-clamp recordings of rats 24 h after CFA injection showed that excitatory postsynaptic currents of dorsal horn neurons evoked by pinch stimuli to inflamed skin were inwardly rectified and inhibited by 60% by philanthotoxin-433, a selective inhibitor of the Ca2+-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor. These results suggest that peripheral inflammation gives rise to central sensitization in the spinal cord through subunit composition switch of AMPA receptors in the late phase.European Journal of Neuroscience 07/2008; 27(12):3161-70. · 3.63 Impact Factor -
Chapter: In Vivo Patch-Clamp Technique
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ABSTRACT: The whole-cell patch-clamp recording technique (Marty and Neher, 1995) is nowadays a standard method for studying electrophysiological properties of the cellular membranes and synaptic inputs. This technique has been applied mainly to in vitro preparations such as culture cells, dissociated cells, and brain slices, contributing greatly to our understanding of ionic mechanisms of channels/receptors, and synaptic transmission in the neuronal circuits. However, the physiological significance of the neuronal and synaptic activities observed in such in vitro preparations remains to be clarified.03/2008: pages 229-251; -
Article: [Function of spinal GABA receptor and its modulation].
Masui. The Japanese journal of anesthesiology 12/2007; 56 Suppl:S141-51. -
Article: [Analysis of hypnotic or analgesic effect of anesthetic agents by in-vivo patch clamp recordings from somatosensory cortex in rats].
Masui. The Japanese journal of anesthesiology 12/2007; 56 Suppl:S99-107. -
Article: [Recent insights into mechanisms for analgesic effect by calcitonin].
Nippon rinsho. Japanese journal of clinical medicine 12/2007; 65 Suppl 9:386-90. -
Article: Slow oscillation of membrane currents mediated by glutamatergic inputs of rat somatosensory cortical neurons: in vivo patch-clamp analysis.
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ABSTRACT: Using in vivo patch-clamp technique, the slow oscillation of membrane currents was characterized by its synaptic nature, correlation with electroencephalogram (EEG) and responses to different anesthetic agents, in primary somatosensory cortex (SI) neurons in urethane-anesthetized rats. In more than 90% of the SI neurons, the slow oscillation of the inward currents (0.1-2.5 Hz) with the duration of several hundreds of a millisecond was observed at the holding membrane potential of -70 mV. The reversal potential of the inward currents was approximately 0 mV and was suppressed by application of an alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor antagonist. In most cases (> 90%) the inward current was synchronized with positive wave of the surface EEG recorded from ipsilateral and even contralateral cortical regions. The frequency as well as duration of the slow oscillation decreased by a volatile anesthetic agent, isoflurane (1.5-5.0%), and excitatory postsynaptic currents (EPSCs) were almost abolished at the highest concentration. Intraperitoneal injection of pentobarbital (25 mg/kg) also decreased the frequency of the slow oscillation without affecting short EPSCs. When gamma-aminobutyric acid A (GABA(A)) receptors were activated by local microinjection of muscimol (3 x 10(-3) m, 1-10 microL) into the thalamus, the frequency of the slow oscillation markedly decreased, but was not abolished completely. These findings suggest that the slow oscillation of the inward currents is generated by the summation of glutamatergic EPSCs, and affected by isoflurane and pentobarbital differently. In addition, GABAergic system in the thalamus can affect the frequency, but is not essentially implicated in the genesis of the slow oscillation.European Journal of Neuroscience 12/2007; 26(9):2565-75. · 3.63 Impact Factor -
Article: Reduced pain behaviors and extracellular signal-related protein kinase activation in primary sensory neurons by peripheral tissue injury in mice lacking platelet-activating factor receptor.
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ABSTRACT: Peripheral tissue injury causes the release of various mediators from damaged and inflammatory cells, which in turn activates and sensitizes primary sensory neurons and thereby produces persistent pain. The present study investigated the role of platelet-activating factor (PAF), a phospholipid mediator, in pain signaling using mice lacking PAF receptor (pafr-/- mice). Here we show that pafr-/- mice displayed almost normal responses to thermal and mechanical stimuli but exhibit attenuated persistent pain behaviors resulting from tissue injury by locally injecting formalin at the periphery as well as capsaicin pain and visceral inflammatory pain without any alteration in cytoarchitectural or neurochemical properties in dorsal root ganglion (DRG) neurons and a defect in motor function. However, pafr-/- mice showed no alterations in spinal pain behaviors caused by intrathecally administering agonists for N-methyl-d-aspartate (NMDA) and neurokinin(1) receptors. A PAFR agonist evoked an intracellular Ca(2+) response predominantly in capsaicin-sensitive DRG neurons, an effect was not observed in pafr-/- mice. By contrast, the PAFR agonist did not affect C- or Adelta-evoked excitatory post-synaptic currents in substantia gelatinosa neurons in the dorsal horn. Interestingly, mice lacking PAFR showed reduced phosphorylation of extracellular signal-related protein kinase (ERK), an important kinase for the sensitization of primary sensory neurons, in their DRG neurons after formalin injection. Furthermore, U0126, a specific inhibitor of the ERK pathway suppressed the persistent pain by formalin. Thus, PAFR may play an important role in both persistent pain and the sensitization of primary sensory neurons after tissue injury.Journal of Neurochemistry 10/2007; 102(5):1658-68. · 4.06 Impact Factor
Top co-authors
Top Journals
Institutions
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2010
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Kumamoto University
Kumamoto-shi, Kumamoto Prefecture, Japan
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2003–2010
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Kyushu University
- • Graduate School of Medical Sciences
- • Faculty of Pharmaceutical Sciences
Fukuoka-shi, Fukuoka-ken, Japan
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2009
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Chinese Academy of Sciences
- Institute of Neuroscience (SIBS)
Beijing, Beijing Shi, China
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2007
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University of Chicago
Chicago, IL, USA -
Columbia University
New York City, NY, USA
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2004–2007
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Asahi Kasei Pharma
Tokyo, Tokyo-to, Japan
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2006
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University of Pittsburgh
- Department of Neurobiology
Pittsburgh, PA, USA
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2005
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University of Toronto
- Department of Physiology
Toronto, Ontario, Canada -
Saga University
- Faculty of Medicine
Saga-shi, Saga-ken, Japan
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