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Sample records for rat sensory neurons

  1. Some Rat Sensory Neurons in Culture Express Characteristics of Differentiated Pain Sensory Cells

    NASA Astrophysics Data System (ADS)

    Baccaglini, Paola I.; Hogan, Patrick G.

    1983-01-01

    Sensory neurons were dissociated from trigeminal ganglia or from dorsal root ganglia of rats, grown in culture, and examined for expression of properties of pain sensory cells. Many sensory neurons in culture are excited by low concentrations of capsaicin, reportedly a selective stimulus for pain sensory neurons. Many are excited by bradykinin, sensitized by prostaglandin E2, or specifically stained by an antiserum against substance P. These experiments provide a basis for the study of pain mechanisms in cell culture.

  2. Apoptotic death of olfactory sensory neurons in the adult rat.

    PubMed

    Deckner, M L; Risling, M; Frisén, J

    1997-01-01

    Olfactory sensory neurons only live for about 1 month in most mammals. It is not fully understood whether the short life span of these neurons is due to necrotic death, or if these cells die by apoptosis. One characteristic of cells undergoing apoptotic cell death is internucleosomal DNA-fragmentation. We have used TdT-mediated dUTP-digoxigenin nick end labeling (TUNEL) to detect cells undergoing DNA-fragmentation in situ. In the intact olfactory epithelium of adult rats a subpopulation of basal immature neuronal progenitor cells, as well as mature olfactory sensory neurons, showed DNA-fragmentation. The number of TUNEL-labeled neurons increased dramatically 1.5 days after transection of the fila olfactoria and declined to control levels by Day 4 after the injury. In order to relate DNA-fragmentation to ultrastructural characteristics of apoptosis we modified the TUNEL-labeling protocol to enable studies of TUNEL-labeled cells in the electron microscope. This confirmed that TUNEL-labeled neurons showed morphological characteristics of apoptosis. The data provide evidence for apoptotic death of neurons in the adult mammalian nervous system. The turnover of olfactory sensory neurons is, at least in part, regulated by apoptosis and disruption of the contact with the olfactory bulb results in massive apoptotic death of neurons in the olfactory epithelium.

  3. Photostimulation of sensory neurons of the rat vagus nerve

    NASA Astrophysics Data System (ADS)

    Rhee, Albert Y.; Li, Gong; Wells, Jonathon; Kao, Joseph P. Y.

    2008-02-01

    We studied the effect of infrared (IR) stimulation on rat sensory neurons. Primary sensory neurons were prepared by enzymatic dissociation of the inferior (or "nodose") ganglia from the vagus nerves of rats. The 1.85-μm output of a diode laser, delivered through a 200-μm silica fiber, was used for photostimulation. Nodose neurons express the vanilloid receptor, TRPV1, which is a non-selective cation channel that opens in response to significant temperature jumps above 37 C. Opening TRPV1 channels allows entry of cations, including calcium (Ca 2+), into the cell to cause membrane depolarization. Therefore, to monitor TRPV1 activation consequent to photostimulation, we used fura-2, a fluorescent Ca 2+ indicator, to monitor the rise in intracellular Ca 2+ concentration ([Ca 2+]i). Brief trains of 2-msec IR pulses activated TRPV1 rapidly and reversibly, as evidenced by transient rises in [Ca 2+]i (referred to as Ca 2+ transients). Consistent with the Ca 2+ transients arising from influx of Ca 2+, identical photostimulation failed to evoke Ca 2+ responses in the absence of extracellular Ca 2+. Furthermore, the photo-induced Ca 2+ signals were abolished by capsazepine, a specific blocker of TRPV1, indicating that the responses were indeed mediated by TRPV1. We discuss the feasibility of using focal IR stimulation to probe neuronal circuit properties in intact neural tissue, and compare IR stimulation with another photostimulation technique-focal photolytic release of "caged" molecules.

  4. Sensory feedback synchronizes motor and sensory neuronal networks in the neonatal rat spinal cord.

    PubMed

    Inácio, Ana R; Nasretdinov, Azat; Lebedeva, Julia; Khazipov, Roustem

    2016-10-07

    Early stages of sensorimotor system development in mammals are characterized by the occurrence of spontaneous movements. Whether and how these movements support correlated activity in developing sensorimotor spinal cord circuits remains unknown. Here we show highly correlated activity in sensory and motor zones in the spinal cord of neonatal rats in vivo. Both during twitches and complex movements, movement-generating bursts in motor zones are followed by bursts in sensory zones. Deafferentation does not affect activity in motor zones and movements, but profoundly suppresses activity bursts in sensory laminae and results in sensorimotor uncoupling, implying a primary role of sensory feedback in sensorimotor synchronization. This is further supported by largely dissociated activity in sensory and motor zones observed in the isolated spinal cord in vitro. Thus, sensory feedback resulting from spontaneous movements is instrumental for coordination of activity in developing sensorimotor spinal cord circuits.

  5. Sensory feedback synchronizes motor and sensory neuronal networks in the neonatal rat spinal cord

    PubMed Central

    Inácio, Ana R.; Nasretdinov, Azat; Lebedeva, Julia; Khazipov, Roustem

    2016-01-01

    Early stages of sensorimotor system development in mammals are characterized by the occurrence of spontaneous movements. Whether and how these movements support correlated activity in developing sensorimotor spinal cord circuits remains unknown. Here we show highly correlated activity in sensory and motor zones in the spinal cord of neonatal rats in vivo. Both during twitches and complex movements, movement-generating bursts in motor zones are followed by bursts in sensory zones. Deafferentation does not affect activity in motor zones and movements, but profoundly suppresses activity bursts in sensory laminae and results in sensorimotor uncoupling, implying a primary role of sensory feedback in sensorimotor synchronization. This is further supported by largely dissociated activity in sensory and motor zones observed in the isolated spinal cord in vitro. Thus, sensory feedback resulting from spontaneous movements is instrumental for coordination of activity in developing sensorimotor spinal cord circuits. PMID:27713428

  6. Taurine replacement attenuates hyperalgesia and abnormal calcium signaling in sensory neurons of STZ-D rats.

    PubMed

    Li, Fei; Obrosova, Irina G; Abatan, Omorodola; Tian, Dequan; Larkin, Dennis; Stuenkel, Edward L; Stevens, Martin J

    2005-01-01

    The etiology of painful diabetic neuropathy is poorly understood, but may result from neuronal hyperexcitability secondary to alterations of Ca2+ signaling in sensory neurons. The naturally occurring amino acid taurine functions as an osmolyte, antioxidant, Ca2+ modulator, inhibitory neurotransmitter, and analgesic such that its depletion in diabetes may predispose one to neuronal hyperexcitability and pain. This study reports the effects of taurine replacement on hyperalgesia and sensory neuron Ca2+ homeostasis in streptozotocin-diabetic (STZ-D) rats. Nondiabetic and STZ-D rats were treated with a 2% taurine-supplemented diet for 6-12 wk. Thermal hyperalgesia and mechanical allodynia were determined by measuring hindpaw withdrawal latency to radiant heat and the withdrawal threshold to the von Frey anesthesiometer. Intracellular Ca2+ signaling was explored in neurons from L4-L6 dorsal root ganglia (DRG), using fura 2 fluorescence. Taurine replacement of diabetic rats attenuated deficits of nerve conduction and prevented reductions of mechanical and thermal withdrawal threshold and latency, respectively. In small DRG sensory neurons from diabetic rats, recovery of intracellular Ca2+ concentration ([Ca2+]i) in response to KCl was slowed and 73% corrected by taurine. The amplitudes of caffeine and ATP-induced [Ca2+]i transients were decreased by 47 and 27% (P < 0.05), respectively, in diabetic rat DRG sensory neurons and corrected by 74 and 93% (P < 0.05), respectively, by taurine replacement. These data indicate that taurine is important in the regulation of neuronal Ca2+ signaling and that taurine deficiency may predispose one to nerve hyperexcitability and pain, complicating diabetes.

  7. NGF induces neonatal rat sensory neurons to extend dendrites in culture after removal of satellite cells.

    PubMed

    De Koninck, P; Carbonetto, S; Cooper, E

    1993-02-01

    Vertebrate sensory neurons have a pseudo-unipolar morphology; their somata are covered by satellite cells and lack dendrites or synaptic contacts. However, when neonatal rat sensory neurons from the nodose ganglia develop in culture in absence of satellite cells and with NGF, they form synapses among themselves. In this study, we investigated whether neonatal rat nodose neurons express dendrites under the same culture conditions. We show by Lucifer yellow injection that nodose neurons remain typically unipolar when cocultured with their ganglionic satellite cells. However, when these neurons are cultured without satellite cells, virtually all neurons acquire a multipolar morphology. Moreover, when NGF is added to satellite cell-free cultures, several neurons extend dendrites; these processes stain positively for microtubule-associated protein-2. NGF induces a 17-fold increase in dendritic outgrowth after 3 weeks but has little effect on axon number. In addition, we find that the ability of nodose neurons to extend dendrites is developmentally regulated. Furthermore, in a combined morphological and electrophysiological study, using whole-cell voltage-clamp technique with Lucifer yellow in the recording solution, we demonstrate a positive correlation between the extent of dendritic outgrowth and the density of ACh currents, suggesting that these dendrites have ACh receptors. Our results indicate that neonatal rat nodose neurons are capable of extending dendrites and that extrinsic factors can induce or suppress their extension. In addition, the results suggest that these dendrites may act as principal post-synaptic structures for synapse formation that occurs in these cultures.

  8. Impaired basal thermal homeostasis in rats lacking capsaicin-sensitive peripheral small sensory neurons.

    PubMed

    Yamashita, Hitoshi; Wang, Zuocheng; Wang, Youxue; Furuyama, Tatsuo; Kontani, Yasuhide; Sato, Yuzo; Mori, Nozomu

    2008-03-01

    We studied the effects of selective loss of capsaicin-sensitive primary sensory neurons on thermosensation and thermoregulation in rats. Neonatal capsaicin treatment in rats caused a remarkable decrease in the number of small-diameter neurons in the dorsal root ganglion (DRG) compared with their number in the control rats. Gene expression analysis for various thermo-sensitive transient receptor potential (TRP) channels indicated marked reductions in the mRNA levels of TRPV1 (70%), TRPM8 (46%) and TRPA1 (64%), but not of TRPV2, in the DRG of capsaicin-treated rats compared with those in the control rats. In addition to the heat and cold insensitivity, capsaicin-treated rats showed lower rectal core temperature, higher skin temperature and decreased sensitivity to ambient temperature alteration under normal housing at room temperature, suggesting impaired thermosensation and change in thermoregulation in the rats. Uncoupling protein 1 (UCP1) expression and the thermogenic ability in brown adipose tissues were attenuated in the capsaicin-treated rats. These results indicate a critical role of capsaicin-sensitive sensory neurons in both heat and cool sensation and hence in basal thermal homeostasis, which is balanced by heat release and production including UCP1 thermogenesis, following sensation of the ambient temperature.

  9. Effects of sensory deprivation on columnar organization of neuronal circuits in the rat barrel cortex.

    PubMed

    Schierloh, Anja; Eder, Matthias; Zieglgänsberger, Walter; Dodt, Hans-Ulrich

    2004-08-01

    We examined whether sensory deprivation during formation of the cortical circuitry influences the pattern of intracortical single-cell connections in rat barrel cortex. Excitatory postsynaptic potentials (EPSPs) from layer 2/3 (L2/3) pyramidal neurons were recorded in vitro using patch-clamp techniques. In order to evoke EPSPs, presynaptic neurons were stimulated by photolytically applied glutamate, thus generating action potentials. Synaptic connections between the stimulated and the recorded neuron were identified by the occurrence of PSPs following photostimulation. Sensory deprivation changed the pattern of projections from L4 and L2/3 neurons to L2/3 pyramidal cells. In slices of non-deprived rats 86% of the total presynaptic neurons were located in the first and only 10% in the second barrel column. Deprivation changed these values to 67% and 26%, respectively. Therefore, the probability of presynaptic cells projecting to L2/3 neurons was shifted from adjacent to more remote barrel columns. These results indicate that deprivation of sensory input influences the pattern of intracortical connections.

  10. Development of nNOS-positive neurons in the rat sensory and sympathetic ganglia.

    PubMed

    Masliukov, P M; Emanuilov, A I; Madalieva, L V; Moiseev, K Y; Bulibin, A V; Korzina, M B; Porseva, V V; Korobkin, A A; Smirnova, V P

    2014-01-03

    Neurochemical features in sympathetic and afferent neurons are subject to change during development. Nitric oxide (NO) plays a developmental role in the nervous system. To better understand the neuroplasticity of sympathetic and afferent neurons during postnatal ontogenesis, the distribution of neuronal NO synthase (nNOS) immunoreactivity was studied in the sympathetic para- and prevertebral, nodose ganglion (NG) and Th2 and L4 dorsal root ganglia (DRG) from female Wistar rats of different ages (newborn, 10-day-old, 20-day-old, 30-day-old, 2-month-old, 6-month-old, 1-year-old, and 3-year-old). nNOS-positive neurons were revealed in all sensory ganglia but not in sympathetic ones from birth onward. The percentage of nNOS-immunoreactive (IR) neurons increased during first 10 days of life from 41.3 to 57.6 in Th2 DRG, from 40.9 to 59.1 in L4 DRG and from 31.6 to 38.5 in NG. The percentage of nNOS-IR neurons did not change in the NG later during development and senescence. However, in Th2 and L4 DRG the proportion of nNOS-IR neurons was high in animals between 10 and 30days of life and decreased up to the second month of life. In 2-month-old rats, the percentage of nNOS-IR neurons was 52.9 in Th2 DRG and 51.3 in L4 DRG. We did not find statistically significant differences in the percentage of nNOS-IR neurons between Th2 and L4 DRG and between young and aged rats. In NG and DRG of 10-day-old and older rats, a high proportion of nNOS-IR neurons binds isolectin B4. In newborn animals, only 41.3%, 45.3% and 28.4% of nNOS neuron profiles bind to IB4 in Th2, L4 DRG and NG, respectively. In 10-day-old and older rats, the number of sensory nNOS-IR neurons binding IB4 reached more than 90% in DRG and more than 80% in NG. Only a small number of nNOS-positive cells showed immunoreactivity to calcitonin gene-related peptide, neurofilament 200, calretinin. The information provided here will also serve as a basis for future studies investigating mechanisms of the development of

  11. Substratum preferences of motor and sensory neurons in postnatal and adult rats.

    PubMed

    Gonzalez-Perez, Francisco; Alé, Albert; Santos, Daniel; Barwig, Christina; Freier, Thomas; Navarro, Xavier; Udina, Esther

    2016-02-01

    After peripheral nerve injuries, damaged axons can regenerate but functional recovery is limited by the specific reinnervation of targets. In this study we evaluated if motor and sensory neurites have a substrate preference for laminin and fibronectin in postnatal and adult stages. In postnatal dorsal root ganglia (DRG) explants, sensory neurons extended longer neurites on collagen matrices enriched with laminin (~50%) or fibronectin (~35%), whereas motoneurons extended longer neurites (~100%) in organotypic spinal cord slices embedded in fibronectin-enriched matrix. An increased percentage of parvalbumin-positive neurites (presumptive proprioceptive) vs. neurofilament-positive neurites was also found in DRG in fibronectin-enriched matrix. To test if the different preference of neurons for extracellular matrix components was maintained in vivo, these matrices were used to fill a chitosan guide to repair a 6-mm gap in the sciatic nerve of adult rats. However, the number of regenerating motor and sensory neurons after 1 month was similar between groups. Moreover, none of the retrotraced sensory neurons in DRG was positive for parvalbumin, suggesting that presumptive proprioceptive neurons had poor regenerative capabilities compared with other peripheral neurons. Using real-time PCR we evaluated the expression of α5β1 (receptor for fibronectin) and α7β1 integrin (receptor for laminin) in spinal cord and DRG 2 days after injury. Postnatal animals showed a higher increase of α5β1 integrin, whereas both integrins were similarly expressed in adult neurons. Therefore, we conclude that motor and sensory axons have a different substrate preference at early postnatal stages but this difference is lost in the adult. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  12. Trigeminothalamic barrelette neurons: natural structural side asymmetries and sensory input-dependent plasticity in adult rats.

    PubMed

    Negredo, P; Martin, Y B; Lagares, A; Castro, J; Villacorta, J A; Avendaño, C

    2009-11-10

    In the rodent trigeminal principal nucleus (Pr5) the barrelette thalamic-projecting neurons relay information from individual whiskers to corresponding contralateral thalamic barreloids. Here we investigated the presence of lateral asymmetries in the dendritic trees of these neurons, and the morphometric changes resulting from input-dependent plasticity in young adult rats. After retrograde labeling with dextran amines from the thalamus, neurons were digitally reconstructed with Neurolucida, and metrically and topologically analyzed with NeuroExplorer. The most unexpected and remarkable result was the observation of side-to-side asymmetries in the barrelette neurons of control rats. These asymmetries more significantly involved the number of low-grade trees and the total dendritic length, which were greater on the left side. Chronic global input loss resulting from infraorbital nerve (IoN) transection, or loss of active touch resulting from whisker clipping in the right neutralized, or even reversed, the observed lateral differences. While results after IoN transection have to be interpreted in the context of partial neuron death in this model, profound bilateral changes were found after haptic loss, which is achieved without inflicting any nerve damage. After whisker trimming, neurons on the left side closely resembled neurons on the right in controls, the natural dendritic length asymmetry being reversed mainly by a shortening of the left trees and a more moderate elongation of the right trees. These results demonstrate that dendritic morphometry is both side- and input-dependent, and that unilateral manipulation of the sensory periphery leads to bilateral morphometric changes in second order neurons of the whisker-barrel system. The presence of anatomical asymmetries in neural structures involved in early stages of somatosensory processing could help explain the expression of sensory input-dependent behavioral asymmetries.

  13. Actions of neuropoietic cytokines and cyclic AMP in regenerative conditioning of rat primary sensory neurons.

    PubMed

    Wu, Dongsheng; Zhang, Yi; Bo, Xuenong; Huang, Wenlong; Xiao, Fang; Zhang, Xinyu; Miao, Tizong; Magoulas, Charalambos; Subang, Maria C; Richardson, Peter M

    2007-03-01

    A conditioning lesion to peripheral axons of primary sensory neurons accelerates regeneration of their central axons in vivo or neurite outgrowth if the neurons are grown in vitro. Previous evidence has implicated neuropoietic cytokines and also cyclic AMP in regenerative conditioning. In experiments reported here, delivery through a lentivirus vector of ciliary neurotrophic factor to the appropriate dorsal root ganglion in rats was sufficient to mimic the conditioning effect of peripheral nerve injury on the regeneration of dorsal spinal nerve root axons. Regeneration in this experimental preparation was also stimulated by intraganglionic injection of dibutyryl cyclic AMP but the effects of ciliary neurotrophic factor and dibutyryl cyclic AMP were not additive. Dibutyryl cyclic AMP injection into the dorsal root ganglion induced mRNAs for two other neuropoietic cytokines, interleukin-6 and leukemia inhibitory factor and increased the accumulation of phosphorylated STAT3 in neuronal nuclei. The in vitro conditioning action of dibutyryl cyclic AMP was partially blocked by a pharmacological inhibitor of Janus kinase 2, a neuropoietic cytokine signaling molecule. We suggest that the beneficial actions of increased cyclic AMP activity on axonal regeneration of primary sensory neurons are mediated, at least in part, through the induction of neuropoietic cytokine synthesis within the dorsal root ganglion.

  14. Moderate hypoxia influences excitability and blocks dendrotoxin sensitive K+ currents in rat primary sensory neurones

    PubMed Central

    Gruss, Marco; Ettorre, Giovanni; Stehr, Annette Jana; Henrich, Michael; Hempelmann, Gunter; Scholz, Andreas

    2006-01-01

    Hypoxia alters neuronal function and can lead to neuronal injury or death especially in the central nervous system. But little is known about the effects of hypoxia in neurones of the peripheral nervous system (PNS), which survive longer hypoxic periods. Additionally, people have experienced unpleasant sensations during ischemia which are dedicated to changes in conduction properties or changes in excitability in the PNS. However, the underlying ionic conductances in dorsal root ganglion (DRG) neurones have not been investigated in detail. Therefore we investigated the influence of moderate hypoxia (27.0 ± 1.5 mmHg) on action potentials, excitability and ionic conductances of small neurones in a slice preparation of DRGs of young rats. The neurones responded within a few minutes non-uniformly to moderate hypoxia: changes of excitability could be assigned to decreased outward currents in most of the neurones (77%) whereas a smaller group (23%) displayed increased outward currents in Ringer solution. We were able to attribute most of the reduction in outward-current to a voltage-gated K+ current which activated at potentials positive to -50 mV and was sensitive to 50 nM α-dendrotoxin (DTX). Other toxins that inhibit subtypes of voltage gated K+ channels, such as margatoxin (MgTX), dendrotoxin-K (DTX-K), r-tityustoxin Kα (TsTX-K) and r-agitoxin (AgTX-2) failed to prevent the hypoxia induced reduction. Therefore we could not assign the hypoxia sensitive K+ current to one homomeric KV channel type in sensory neurones. Functionally this K+ current blockade might underlie the increased action potential (AP) duration in these neurones. Altogether these results, might explain the functional impairment of peripheral neurones under moderate hypoxia. PMID:16579848

  15. Reproductive experience modified dendritic spines on cortical pyramidal neurons to enhance sensory perception and spatial learning in rats.

    PubMed

    Chen, Jeng-Rung; Lim, Seh Hong; Chung, Sin-Cun; Lee, Yee-Fun; Wang, Yueh-Jan; Tseng, Guo-Fang; Wang, Tsyr-Jiuan

    2017-01-27

    Behavioral adaptations during motherhood are aimed at increasing reproductive success. Alterations of hormones during motherhood could trigger brain morphological changes to underlie behavioral alterations. Here we investigated whether motherhood changes a rat's sensory perception and spatial memory in conjunction with cortical neuronal structural changes. Female rats of different statuses, including virgin, pregnant, lactating, and primiparous rats were studied. Behavioral test showed that the lactating rats were most sensitive to heat, while rats with motherhood and reproduction experience outperformed virgin rats in a water maze task. By intracellular dye injection and computer-assisted 3-dimensional reconstruction, the dendritic arbors and spines of the layer III and V pyramidal neurons of the somatosensory cortex and CA1 hippocampal pyramidal neurons were revealed for closer analysis. The results showed that motherhood and reproductive experience increased dendritic spines but not arbors or the lengths of the layer III and V pyramidal neurons of the somatosensory cortex and CA1 hippocampal pyramidal neurons. In addition, lactating rats had a higher incidence of spines than pregnant or primiparous rats. The increase of dendritic spines was coupled with increased expression of the glutamatergic postsynaptic marker protein (PSD-95), especially in lactating rats. On the basis of the present results, it is concluded that motherhood enhanced rat sensory perception and spatial memory and was accompanied by increases in dendritic spines on output neurons of the somatosensory cortex and CA1 hippocampus. The effect was sustained for at least 6 weeks after the weaning of the pups.

  16. Reproductive experience modified dendritic spines on cortical pyramidal neurons to enhance sensory perception and spatial learning in rats

    PubMed Central

    Chen, Jeng-Rung; Lim, Seh Hong; Chung, Sin-Cun; Lee, Yee-Fun; Wang, Yueh-Jan; Tseng, Guo-Fang; Wang, Tsyr-Jiuan

    2016-01-01

    Behavioral adaptations during motherhood are aimed at increasing reproductive success. Alterations of hormones during motherhood could trigger brain morphological changes to underlie behavioral alterations. Here we investigated whether motherhood changes a rat’s sensory perception and spatial memory in conjunction with cortical neuronal structural changes. Female rats of different statuses, including virgin, pregnant, lactating, and primiparous rats were studied. Behavioral test showed that the lactating rats were most sensitive to heat, while rats with motherhood and reproduction experience outperformed virgin rats in a water maze task. By intracellular dye injection and computer-assisted 3-dimensional reconstruction, the dendritic arbors and spines of the layer III and V pyramidal neurons of the somatosensory cortex and CA1 hippocampal pyramidal neurons were revealed for closer analysis. The results showed that motherhood and reproductive experience increased dendritic spines but not arbors or the lengths of the layer III and V pyramidal neurons of the somatosensory cortex and CA1 hippocampal pyramidal neurons. In addition, lactating rats had a higher incidence of spines than pregnant or primiparous rats. The increase of dendritic spines was coupled with increased expression of the glutamatergic postsynaptic marker protein (PSD-95), especially in lactating rats. On the basis of the present results, it is concluded that motherhood enhanced rat sensory perception and spatial memory and was accompanied by increases in dendritic spines on output neurons of the somatosensory cortex and CA1 hippocampus. The effect was sustained for at least 6 weeks after the weaning of the pups. PMID:27784858

  17. Gastrodin inhibits the activity of acid-sensing ion channels in rat primary sensory neurons.

    PubMed

    Qiu, Fang; Liu, Ting-Ting; Qu, Zu-Wei; Qiu, Chun-Yu; Yang, Zhifan; Hu, Wang-Ping

    2014-05-15

    Acid-sensing ion channels (ASICs), a family of proton-gated cation channels, are believed to mediate pain caused by extracellular acidification. Gastrodin is a main bioactive constituent of the traditional herbal Gastrodia elata Blume, which has been widely used in Oriental countries for centuries. As an analgesic, gastrodin has been used clinically to treat pain such as migraine and headache. However, the mechanisms underlying analgesic action of gastrodin are still poorly understood. Here, we have found that gastrodin inhibited the activity of native ASICs in rat dorsal root ganglion (DRG) neurons. Gastrodin dose-dependently inhibited proton-gated currents mediated by ASICs. Gastrodin shifted the proton concentration-response curve downwards, with a decrease of 36.92 ± 6.23% in the maximum current response but with no significant change in the pH0.5 value. Moreover, gastrodin altered acid-evoked membrane excitability of rat DRG neurons and caused a significant decrease in the amplitude of the depolarization and the number of action potentials induced by acid stimuli. Finally, peripheral applied gastrodin relieved pain evoked by intraplantar injection of acetic acid in rats. Our results indicate that gastrodin can inhibit the activity of ASICs in the primary sensory neurons, which provided a novel mechanism underlying analgesic action of gastrodin.

  18. Thyroid hormone reduces the loss of axotomized sensory neurons in dorsal root ganglia after sciatic nerve transection in adult rat.

    PubMed

    Schenker, Michel; Kraftsik, Rudolf; Glauser, Liliane; Kuntzer, Thierry; Bogousslavsky, Julien; Barakat-Walter, Ibtissam

    2003-11-01

    We have shown that a local administration of thyroid hormones (T3) at the level of transected rat sciatic nerve induced a significant increase in the number of regenerated axons. To address the question of whether local administration of T3 rescues the axotomized sensory neurons from death, in the present study we estimated the total number of surviving neurons per dorsal root ganglion (DRG) in three experimental group animals. Forty-five days following rat sciatic nerve transection, the lumbar (L4 and L5) DRG were removed from PBS-control, T3-treated as well as from unoperated rats, and serial sections (1 microm) were cut. The physical dissector method was used to estimate the total number of sensory neurons in the DRGs. Our results revealed that in PBS-control rats transection of sciatic nerve leads to a significant (P < 0.001) decrease in the mean number of sensory neurons (8743.8 +/- 748.6) compared with the number of neurons in nontransected ganglion (mean 13,293.7 +/- 1368.4). However, administration of T3 immediately after sciatic nerve transection rescues a great number of axotomized neurons so that their mean neuron number (12,045.8 +/- 929.8) is not significantly different from the mean number of neurons in the nontransected ganglion. In addition, the volume of ganglia showed a similar tendency. These results suggest that T3 rescues a high number of axotomized sensory neurons from death and allows these cells to grow new axons. We believe that the relative preservation of neurons is important in considering future therapeutic approaches of human peripheral nerve lesion and sensory neuropathy.

  19. Regulation of acid signaling in rat pulmonary sensory neurons by protease-activated receptor-2

    PubMed Central

    Lee, Lu-Yuan

    2010-01-01

    Airway acidification has been consistently observed in airway inflammatory conditions and is known to cause cardiorespiratory symptoms that are, at least in part, mediated through the activation of bronchopulmonary C fibers and the subsequent reflexes. Protease-activated receptor-2 (PAR2) is expressed in a variety of cells in the lung and airways and is believed to play a role in airway inflammation and hyperresponsiveness. This study was carried out to investigate the effect of PAR2 activation on the acid signaling in rat bronchopulmonary C-fiber sensory neurons. Our RT-PCR results revealed the expression of mRNAs for transient receptor potential vanilloid receptor 1 (TRPV1) and four functional acid-sensing ion channel (ASIC) subunits 1a, 1b, 2a, and 3 in these sensory neurons. Preincubation of SLIGRL-NH2, a specific PAR2-activating peptide, markedly enhanced the Ca2+ transient evoked by extracellular acidification. Pretreatment with PAR2 agonists significantly potentiated both acid-evoked ASIC- and TRPV1-like whole cell inward currents. Activation of PAR2 also potentiated the excitability of these neurons to acid, but not electrical stimulation. In addition, the potentiation of acid-evoked responses was not prevented by inhibiting either PLC or PKC nor was mimicked by activation of PKC. In conclusion, activation of PAR2 modulates the acid signaling in pulmonary sensory neurons, and the interaction may play a role in the pathogenesis of airway inflammatory conditions, where airway acidification and PAR2 activation can occur simultaneously. PMID:20044436

  20. Emergence of intrinsic bursting in trigeminal sensory neurons parallels the acquisition of mastication in weanling rats.

    PubMed

    Brocard, Frédéric; Verdier, Dorly; Arsenault, Isabel; Lund, James P; Kolta, Arlette

    2006-11-01

    There is increasing evidence that a subpopulation of neurons in the dorsal principal sensory trigeminal nucleus are not simple sensory relays to the thalamus but may form the core of the central pattern generating circuits responsible for mastication. In this paper, we used whole cell patch recordings in brain stem slices of young rats to show that these neurons have intrinsic bursting abilities that persist in absence of extracellular Ca(2+). Application of different K(+) channel blockers affected duration and firing rate of bursts, but left bursting ability intact. Bursting was voltage dependent and was abolished by low concentrations of Na(+) channel blockers. The proportion of bursting neurons increased dramatically in the second postnatal week, in parallel with profound changes in several electrophysiological properties. This is the period in which masticatory movements appear and mature. Bursting was associated with the development of an afterdepolarization that depend on maturation of a persistent sodium conductance (I(NaP)). An interesting finding was that the occurrence of bursting and the magnitude of I(NaP) were both modulated by the extracellular concentration of Ca(2+). Lowering extracellular [Ca(2+)] increased both I(NaP) and probability of bursting. We suggest that these mechanisms underlie burst generation in mastication and that similar processes may be found in other motor pattern generators.

  1. Modulation of action potential and calcium signaling by levetiracetam in rat sensory neurons.

    PubMed

    Ozcan, Mete; Ayar, Ahmet

    2012-06-01

    Levetiracetam (LEV), a new anticonvulsant agent primarily used to treat epilepsy, has been used in pain treatment but the cellular mechanism of this action remains unclear. This study aimed to investigate effects of LEV on the excitability and membrane depolarization-induced calcium signaling in isolated rat sensory neurons using the whole-cell patch clamp and fura 2-based ratiometric Ca(2+)-imaging techniques. Dorsal root ganglia (DRG) were excised from neonatal rats, and cultured following enzymatic and mechanical dissociation. Under current clamp conditions, acute application of LEV (30 µM, 100 µM and 300 µM) significantly increased input resistance and caused the membrane to hyperpolarize from resting membrane potential in a dose-dependent manner. Reversal potentials of action potential (AP) after hyperpolarising amplitudes were shifted to more negative, toward to potassium equilibrium potentials, after application of LEV. It also caused a decrease in number of APs in neurons fired multiple APs in response to prolonged depolarization. Fura-2 fluorescence Ca(2+) imaging protocols revealed that HiK(+) (30 mM)-induced intracellular free Ca(2+) ([Ca(2+)](i)) was inhibited to 97.8 ± 4.6% (n = 17), 92.6 ± 4.8% (n = 17, p < 0.01) and 89.1 ± 5.1% (n = 18, p < 0.01) after application of 30 µM, 100 µM and 300 µM LEV (respectively), without any significant effect on basal levels of [Ca(2+)](i). This is the first evidence for the effect of LEV on the excitability of rat sensory neurons through an effect which might involve activation of potassium channels and inhibition of entry of Ca(2+), providing new insights for cellular mechanism(s) of LEV in pain treatment modalities.

  2. Rat thalamic neurons encode complex combinations of heading and movement directions and the trajectory route during translocation with sensory conflict

    PubMed Central

    Enkhjargal, Nyamdavaa; Matsumoto, Jumpei; Chinzorig, Choijiljav; Berthoz, Alain; Ono, Taketoshi; Nishijo, Hisao

    2014-01-01

    It is unknown how thalamic head direction neurons extract meaningful information from multiple conflicting sensory information sources when animals run under conditions of sensory mismatch. In the present study, rats were placed on a treadmill on a stage that moved in a figure-8-shaped pathway. The anterodorsal and laterodorsal neurons were recorded under two conditions: (1) control sessions, in which both the stage and the treadmill moved forward, or (2) backward (mismatch) sessions, in which the stage was moved backward while the rats ran forward on the treadmill. Of the 222 thalamic neurons recorded, 55 showed differential responses to the directions to window (south) and door (north) sides, along which the animals were translocated in the long axis of the trajectory. Of these 55 direction-related neurons, 15 showed heading direction-dependent responses regardless of movement direction (forward or backward movements). Thirteen neurons displayed heading and movement direction-dependent responses, and, of these 13, activity of 6 neurons increased during forward movement to the window or door side, while activity of the remaining 7 neurons increased during backward movement to the window or door side. Eighteen neurons showed movement direction-related responses regardless of heading direction. Furthermore, activity of some direction-related neurons increased only in a specific trajectory. These results suggested that the activity of these neurons reflects complex combinations of facing direction (landmarks), movement direction (optic flow/vestibular information), motor/proprioceptive information, and the trajectory of the movement. PMID:25100955

  3. Persistent Neuronal Activity in Anterior Cingulate Cortex Correlates with Sustained Attention in Rats Regardless of Sensory Modality

    PubMed Central

    Wu, Dingcheng; Deng, Hanfei; Xiao, Xiong; Zuo, Yanfang; Sun, Jingjing; Wang, Zuoren

    2017-01-01

    The anterior cingulate cortex (ACC) has long been thought to regulate conflict between an object of attention and distractors during goal-directed sustained attention. However, it is unclear whether ACC serves to sustained attention itself. Here, we developed a task in which the time course of sustained attention could be controlled in rats. Then, using pharmacological lesion experiments, we employed it to assess function of ACC in sustained attention. We then recorded neuronal activity in ACC using multichannel extracellular recording techniques and identified specific ACC neurons persistently activated during the period of attention. Further experiments showed that target modality had minimal influence on the neuronal activity, and distracting external sensory input during the attention period did not perturb persistent neuronal activity. Additionally, minimal trial-to-trial variability in neuronal activity observed during sustained attention supports a role for ACC neurons in that behavior. Therefore, we conclude that the ACC neuronal activity correlates with sustained attention. PMID:28230158

  4. A tingling sanshool derivative excites primary sensory neurons and elicits nocifensive behavior in rats

    PubMed Central

    Klein, Amanda H.; Sawyer, Carolyn M.; Zanotto, Karen L.; Ivanov, Margaret A.; Cheung, Susan; Carstens, Mirela Iodi; Furrer, Stephan; Simons, Christopher T.; Slack, Jay P.

    2011-01-01

    Szechuan peppers contain hydroxy-α-sanshool that imparts desirable tingling, cooling, and numbing sensations. Hydroxy-α-sanshool activates a subset of sensory dorsal root ganglion (DRG) neurons by inhibiting two-pore potassium channels. We presently investigated if a tingle-evoking sanshool analog, isobutylalkenyl amide (IBA), excites rat DRG neurons and, if so, if these neurons are also activated by agonists of TRPM8, TRPA1, and/or TRPV1. Thirty-four percent of DRG neurons tested responded to IBA, with 29% of them also responding to menthol, 29% to cinnamic aldehyde, 66% to capsaicin, and subsets responding to two or more transient receptor potential (TRP) agonists. IBA-responsive cells had similar size distributions regardless of whether they responded to capsaicin or not; cells only responsive to IBA were larger. Responses to repeated application of IBA at a 5-min interstimulus interval exhibited self-desensitization (tachyphylaxis). Capsaicin did not cross-desensitize responses to IBA to any greater extent than the tachyphylaxis observed with repeated IBA applications. These findings are consistent with psychophysical observations that IBA elicits tingle sensation accompanied by pungency and cooling, with self-desensitization but little cross-desensitization by capsaicin. Intraplantar injection of IBA elicited nocifensive responses (paw licking, shaking-flinching, and guarding) in a dose-related manner similar to the effects of intraplantar capsaicin and serotonin. IBA had no effect on thermal sensitivity but enhanced mechanical sensitivity at the highest dose tested. These observations suggest that IBA elicits an unfamiliar aversive sensation that is expressed behaviorally by the limited response repertoire available to the animal. PMID:21273322

  5. Wnt/Ryk signaling contributes to neuropathic pain by regulating sensory neuron excitability and spinal synaptic plasticity in rats.

    PubMed

    Liu, Su; Liu, Yue-Peng; Huang, Zhi-Jiang; Zhang, Yan-Kai; Song, Angela A; Ma, Ping-Chuan; Song, Xue-Jun

    2015-12-01

    Treating neuropathic pain continues to be a major clinical challenge and underlying mechanisms of neuropathic pain remain elusive. We have recently demonstrated that Wnt signaling, which is important in developmental processes of the nervous systems, plays critical roles in the development of neuropathic pain through the β-catenin-dependent pathway in the spinal cord and the β-catenin-independent pathway in primary sensory neurons after nerve injury. Here, we report that Wnt signaling may contribute to neuropathic pain through the atypical Wnt/Ryk signaling pathway in rats. Sciatic nerve injury causes a rapid-onset and long-lasting expression of Wnt3a, Wnt5b, and Ryk receptors in primary sensory neurons, and dorsal horn neurons and astrocytes. Spinal blocking of the Wnt/Ryk receptor signaling inhibits the induction and persistence of neuropathic pain without affecting normal pain sensitivity and locomotor activity. Blocking activation of the Ryk receptor with anti-Ryk antibody, in vivo or in vitro, greatly suppresses nerve injury-induced increased intracellular Ca and hyperexcitability of the sensory neurons, and also the enhanced plasticity of synapses between afferent C-fibers and the dorsal horn neurons, and activation of the NR2B receptor and the subsequent Ca-dependent signals CaMKII, Src, ERK, PKCγ, and CREB in sensory neurons and the spinal cord. These findings indicate a critical mechanism underlying the pathogenesis of neuropathic pain and suggest that targeting the Wnt/Ryk signaling may be an effective approach for treating neuropathic pain.

  6. Loss of sensory input increases the intrinsic excitability of layer 5 pyramidal neurons in rat barrel cortex.

    PubMed

    Breton, Jean-Didier; Stuart, Greg J

    2009-11-01

    Development of the cortical map is experience dependent, with different critical periods in different cortical layers. Previous work in rodent barrel cortex indicates that sensory deprivation leads to changes in synaptic transmission and plasticity in layer 2/3 and 4. Here, we studied the impact of sensory deprivation on the intrinsic properties of layer 5 pyramidal neurons located in rat barrel cortex using simultaneous somatic and dendritic recording. Sensory deprivation was achieved by clipping all the whiskers on one side of the snout. Loss of sensory input did not change somatic active and resting membrane properties, and did not influence dendritic action potential (AP) backpropagation. In contrast, sensory deprivation led to an increase in the percentage of layer 5 pyramidal neurons showing burst firing. This was associated with a reduction in the threshold for generation of dendritic calcium spikes during high-frequency AP trains. Cell-attached recordings were used to assess changes in the properties and expression of dendritic HCN channels. These experiments indicated that sensory deprivation caused a decrease in HCN channel density in distal regions of the apical dendrite. To assess the contribution of HCN down-regulation on the observed increase in dendritic excitability following sensory deprivation, we investigated the impact of blocking HCN channels. Block of HCN channels removed differences in dendritic calcium electrogenesis between control and deprived neurons. In conclusion, these observations indicate that sensory loss leads to increased dendritic excitability of cortical layer 5 pyramidal neurons. Furthermore, they suggest that increased dendritic calcium electrogenesis following sensory deprivation is mediated in part via down-regulation of dendritic HCN channels.

  7. Infection by human varicella-zoster virus confers norepinephrine sensitivity to sensory neurons from rat dorsal root ganglia.

    PubMed

    Kress, M; Fickenscher, H

    2001-04-01

    Varicella-zoster virus (VZV) is a widespread human herpes virus causing chicken pox on primary infection and persisting in sensory neurons. Reactivation causes shingles, which are characterized by severe pain and often lead to postherpetic neuralgia. To elucidate the mechanisms of VZV-associated hyperalgesia, we elaborated an in vitro model for the VZV infection of sensory neurons from rat dorsal root ganglia. Between 35 and 50% of the neurons showed strong expression of the immediate-early virus antigens IE62 and IE63 and the late glycoprotein gE. When the intracellular calcium concentration was monitored microfluorometrically for individual cells after infection, the sensitivity to GABA or capsaicin was similar in controls and in VZV-infected neurons. However, the baseline calcium concentration was increased. Neurons became de novo sensitive to adrenergic stimulation after VZV infection. Norepinephrine-responsive neurons were more frequent and calcium responses to norepinephrine were significantly higher after infection with wild-type isolates than with the attenuated vaccine strain OKA. The adrenergic agonists phenylephrine and isoproterenol had similar efficacy. We suggest that the infection with wild-type VZV isolates confers norepinephrine sensitivity to sensory neurons by using alpha(1)- and/or beta(1)-adrenergic receptors providing a model for the pathophysiology of the severe pain associated with the acute reactivation of VZV.

  8. Cytotoxic effect of commercially available methylprednisolone acetate with and without reduced preservatives on dorsal root ganglion sensory neurons in rats.

    PubMed

    Knezevic, Nebojsa Nick; Candido, Kenneth D; Cokic, Ivan; Krbanjevic, Aleksandar; Berth, Sarah L; Knezevic, Ivana

    2014-01-01

    Epidural and intrathecal injections of methylprednisolone acetate (MPA) have become the most commonly performed interventional procedures in the United States and worldwide in the last 2 decades. However neuraxial MPA injection has been dogged by controversy regarding the presence of different additives used in commercially prepared glucocorticoids. We previously showed that MPA could be rendered 85% free of polyethylene glycol (PEG) by a simple physical separation of elements in the suspension. The objective of the present study was to explore a possible cytotoxic effect of commercially available MPA (with intact or reduced preservatives) on rat sensory neurons. We exposed primary dissociated rat dorsal root ganglia (DRG) sensory neurons to commercially available MPA for 24 hours with either the standard (commercial) concentration of preservatives or to different fractions following separation (MPA suspension whose preservative concentration had been reduced, or fractions containing higher concentrations of preservatives). Cells were stained with the TUNEL assay kit to detect apoptotic cells and images were taken on the Bio-Rad Laser Sharp-2000 system. We also detected expression of caspase-3, as an indicator of apoptosis in cell lysates. We exposed sensory neurons from rat DRG to different concentrations of MPA from the original commercially prepared vial. TUNEL assay showed dose-related responses and increased percentages of apoptotic cells with increasing concentrations of MPA. Increased concentrations of MPA caused 1.5 - 2 times higher caspase-3 expression in DRG sensory neurons than in control cells (ANOVA, P = 0.001). Our results showed that MPA with reduced preservatives caused significantly less apoptosis observed with TUNEL assay labeling (P < 0.001) and caspase-3 immunoblotting (P = 0.001) than in neurons exposed to MPA from a commercially prepared vial or "clear phase" that contained higher concentrations of preservatives. Even though MPA with reduced

  9. TRPA1 receptor localisation in the human peripheral nervous system and functional studies in cultured human and rat sensory neurons.

    PubMed

    Anand, U; Otto, W R; Facer, P; Zebda, N; Selmer, I; Gunthorpe, M J; Chessell, I P; Sinisi, M; Birch, R; Anand, P

    2008-06-20

    TRPA1 is a receptor expressed by sensory neurons, that is activated by low temperature (<17 degrees C) and plant derivatives such as cinnamaldehyde and isoeugenol, to elicit sensations including pain. Using immunohistochemistry, we have, for the first time, localised TRPA1 in human DRG neurons, spinal cord motoneurones and nerve roots, peripheral nerves, intestinal myenteric plexus neurones, and skin basal keratinocytes. TRPA1 co-localised with a subset of hDRG neurons positive for TRPV1, the heat and capsaicin receptor. The number of small/medium TRPA1 positive neurons (< or =50 microm) was increased after hDRG avulsion injury [percentage of cells, median (range): controls 16.5 (7-23); injured 46 (34-55); P<0.005], but the number of large TRPA1 neurons was unchanged [control 19.5 (13-31); injured 21 (11-35)]. Similar TRPA1 changes were observed in cultured hDRG neurons, after exposure to a combination of key neurotrophic factors NGF, GDNF and NT-3 (NTFs) in vitro. We used calcium imaging to examine responses of HEK cells transfected with hTRPA1 cDNA, and of human and rat DRG neurons cultured with or without added NTFs, to cinnamaldehyde (CA) and isoeugenol (IE). Exposure to NTFs in vitro sensitized cultured human sensory neuronal responses to CA; repeated CA exposure produced desensitisation. In rDRG neurons, low (225 microM) CA preincubation enhanced capsaicin responses, while high (450 microM and 2mM) CA caused inhibition which was partially reversed in the presence of 8 bromo cAMP, indicating receptor dephosphorylation. While TRPA1 localisation is more widespread than TRPV1, it represents a promising novel drug target for the treatment of chronic pain and hypersensitivity.

  10. A- and C-type rat nodose sensory neurons: model interpretations of dynamic discharge characteristics.

    PubMed

    Schild, J H; Clark, J W; Hay, M; Mendelowitz, D; Andresen, M C; Kunze, D L

    1994-06-01

    1. Neurons of the nodose ganglia provide the sole connection between many types of visceral sensory inputs and the central nervous system. Electrophysiological studies of isolated nodose neurons provide a practical means of measuring individual cell membrane currents and assessing their putative contributions to the overall response properties of the neuron and its terminations. Here, we present a comprehensive mathematical model of an isolated nodose sensory neuron that is based upon numerical fits to quantitative voltage- and current-clamp data recorded in our laboratory. Model development was accomplished using an iterative process of electrophysiological recordings, nonlinear parameter estimation, and computer simulation. This work is part of an integrative effort aimed at identifying and characterizing the fundamental ionic mechanisms participating in the afferent neuronal limb of the baroreceptor reflex. 2. The neuronal model consists of two parts: a Hodgkin-Huxley-type membrane model coupled to a lumped fluid compartment model that describes Ca2+ ion concentration dynamics within the intracellular and external perineuronal media. Calcium buffering via a calmodulin-type buffer is provided within the intracellular compartment. 3. The complete model accurately reproduces whole-cell voltage-clamp recordings of the major ion channel currents observed in enzymatically dispersed nodose sensory neurons. Specifically, two Na+ currents exhibiting fast (INaf) and slow tetrodotoxin (TTX)-insensitive (INas) kinetics; low- and high-threshold Ca2+ currents exhibiting transient (ICa,t) and long-lasting (ICa,n) dynamics, respectively; and outward K+ currents consisting of a delayed-rectifier current (IK), a transient outward current (I(t)) and a Ca(2+)-activated K+ current (IK,Ca). 4. Whole-cell current-clamp recordings of somatic action-potential dynamics were performed on enzymatically dispersed nodose neurons using the perforated patch-clamp technique. Stimulus protocols

  11. Acid-sensing properties in rat gastric sensory neurons from normal and ulcerated stomach.

    PubMed

    Sugiura, Takeshi; Dang, Khoa; Lamb, Kenneth; Bielefeldt, Klaus; Gebhart, G F

    2005-03-09

    Gastric acid contributes to dyspeptic symptoms, including abdominal pain, in patients with disorders of the proximal gastrointestinal tract. To examine the molecular sensor(s) of gastric acid chemonociception, we characterized acid-elicited currents in dorsal root ganglion (DRG) and nodose ganglion (NG) neurons that innervate the stomach and examined their modulation after induction of gastric ulcers. A fluorescent dye (DiI) was injected into the stomach wall to retrogradely label gastric sensory neurons. After 1-2 weeks, gastric ulcers were induced by 45 s of luminal exposure of the stomach to 60% acetic acid injected into a clamped area of the distal stomach; control animals received saline. In whole-cell voltage-clamp recordings, all gastric DRG neurons and 55% of NG neurons exhibited transient, amiloride-sensitive, acid-sensing ion-channel (ASIC) currents. In the remaining 45% of NG neurons, protons activated a slow, sustained current that was attenuated by the transient receptor potential vanilloid subtype 1 antagonist, capsazepine. The kinetics and proton sensitivity of amiloride-sensitive ASIC currents differed between NG and DRG neurons. NG neurons had a lower proton sensitivity and faster kinetics, suggesting expression of specific subtypes of ASICs in the vagal and splanchnic innervation of the stomach. Effects of Zn2+ and N,N,N',N'-tetrakis-(2-pyridylmethyl)-ethylenediamine on acid-elicited currents suggest contributions of ASIC1a and ASIC2a subunits. Gastric ulcers altered the properties of acid-elicited currents by increasing pH sensitivity and current density and changing current kinetics in gastric DRG neurons. The distinct properties of NG and DRG neurons and their modulation after injury suggest differential contributions of vagal and spinal afferent neurons to chemosensation and chemonociception.

  12. The properties, distribution and function of Na(+)-Ca(2+) exchanger isoforms in rat cutaneous sensory neurons.

    PubMed

    Scheff, N N; Yilmaz, E; Gold, M S

    2014-11-15

    The Na(+)-Ca(2+) exchanger (NCX) appears to play an important role in the regulation of the high K(+)-evoked Ca(2+) transient in putative nociceptive dorsal root ganglion (DRG) neurons. The purpose of the present study was to (1) characterize the properties of NCX activity in subpopulations of DRG neurons, (2) identify the isoform(s) underlying NCX activity, and (3) begin to assess the function of the isoform(s) in vivo. In retrogradely labelled neurons from the glabrous skin of adult male Sprague-Dawley rats, NCX activity, as assessed with fura-2-based microfluorimetry, was only detected in putative nociceptive IB4+ neurons. There were two modes of NCX activity: one was evoked in response to relatively large and long lasting (∼325 nm for >12 s) increases in the concentration of intracellular Ca(2+) ([Ca(2+)]i), and a second was active at resting [Ca(2+)]i > ∼150 nm. There also were two modes of evoked activity: one that decayed relatively rapidly (<5 min) and a second that persisted (>10 min). Whereas mRNA encoding all three NCX isoforms (NCX1-3) was detected in putative nociceptive cutaneous neurons with single cell PCR, pharmacological analysis and small interfering RNA (siRNA) knockdown of each isoform in vivo suggested that NCX2 and 3 were responsible for NCX activity. Western blot analyses suggested that NCX isoforms were differentially distributed within sensory neurons. Functional assays of excitability, action potential propagation, and nociceptive behaviour suggest NCX activity has little influence on excitability per se, but instead influences axonal conduction velocity, resting membrane potential, and nociceptive threshold. Together these results indicate that the function of NCX in the regulation of [Ca(2+)]i in putative nociceptive neurons may be unique relative to other cells in which these exchanger isoforms have been characterized and it has the potential to influence sensory neuron properties at multiple levels.

  13. Skin incision induces expression of axonal regeneration-related genes in adult rat spinal sensory neurons

    PubMed Central

    Hill, Caitlin E.; Harrison, Benjamin J.; Rau, Kris K.; Hougland, M. Tyler; Bunge, Mary Bartlett; Mendell, Lorne M.; Petruska, Jeffrey C.

    2010-01-01

    Skin incision and nerve injury both induce painful conditions. Incisional and post-surgical pain is believed to arise primarily from inflammation of tissue and the subsequent sensitization of peripheral and central neurons. The role of axonal regeneration-related processes in development of pain has only been considered when there has been injury to the peripheral nerve itself, even though tissue damage likely induces injury of resident axons. We sought to determine if skin incision would affect expression of regeneration-related genes such as activating transcription factor 3 (ATF3) in dorsal root ganglion (DRG) neurons. ATF3 is absent from DRG neurons of the normal adult rodent, but is induced by injury of peripheral nerves and modulates the regenerative capacity of axons. Image analysis of immunolabeled DRG sections revealed that skin incision led to an increase in the number of DRG neurons expressing ATF3. RT-PCR indicated that other regeneration-associated genes (galanin, GAP-43, Gadd45a) were also increased, further suggesting an injury-like response in DRG neurons. Our finding that injury of skin can induce expression of neuronal injury/regeneration-associated genes may impact how clinical post-surgical pain is investigated and treated. Perspective Tissue injury, even without direct nerve injury, may induce a state of enhanced growth capacity in sensory neurons. Axonal regeneration-associated processes should be considered alongside nerve signal conduction and inflammatory/sensitization processes as possible mechanisms contributing to pain, particularly the transition from acute to chronic pain. PMID:20627820

  14. Block of voltage-gated potassium channels by Pacific ciguatoxin-1 contributes to increased neuronal excitability in rat sensory neurons

    SciTech Connect

    Birinyi-Strachan, Liesl C.; Gunning, Simon J.; Lewis, Richard J.; Nicholson, Graham M. . E-mail: Graham.Nicholson@uts.edu.au

    2005-04-15

    The present study investigated the actions of the polyether marine toxin Pacific ciguatoxin-1 (P-CTX-1) on neuronal excitability in rat dorsal root ganglion (DRG) neurons using patch-clamp recording techniques. Under current-clamp conditions, bath application of 2-20 nM P-CTX-1 caused a rapid, concentration-dependent depolarization of the resting membrane potential in neurons expressing tetrodotoxin (TTX)-sensitive voltage-gated sodium (Na{sub v}) channels. This action was completely suppressed by the addition of 200 nM TTX to the external solution, indicating that this effect was mediated through TTX-sensitive Na{sub v} channels. In addition, P-CTX-1 also prolonged action potential and afterhyperpolarization (AHP) duration. In a subpopulation of neurons, P-CTX-1 also produced tonic action potential firing, an effect that was not accompanied by significant oscillation of the resting membrane potential. Conversely, in neurons expressing TTX-resistant Na{sub v} currents, P-CTX-1 failed to alter any parameter of neuronal excitability examined in this study. Under voltage-clamp conditions in rat DRG neurons, P-CTX-1 inhibited both delayed-rectifier and 'A-type' potassium currents in a dose-dependent manner, actions that occurred in the absence of alterations to the voltage dependence of activation. These actions appear to underlie the prolongation of the action potential and AHP, and contribute to repetitive firing. These data indicate that a block of potassium channels contributes to the increase in neuronal excitability, associated with a modulation of Na{sub v} channel gating, observed clinically in response to ciguatera poisoning.

  15. TRPA1 Is Functionally Expressed Primarily by IB4-Binding, Non-Peptidergic Mouse and Rat Sensory Neurons

    PubMed Central

    Stucky, Cheryl L.

    2012-01-01

    Subpopulations of somatosensory neurons are characterized by functional properties and expression of receptor proteins and surface markers. CGRP expression and IB4-binding are commonly used to define peptidergic and non-peptidergic subpopulations. TRPA1 is a polymodal, plasma membrane ion channel that contributes to mechanical and cold hypersensitivity during tissue injury, making it a key target for pain therapeutics. Some studies have shown that TRPA1 is predominantly expressed by peptidergic sensory neurons, but others indicate that TRPA1 is expressed extensively within non-peptidergic, IB4-binding neurons. We used FURA-2 calcium imaging to define the functional distribution of TRPA1 among peptidergic and non-peptidergic adult mouse (C57BL/6J) DRG neurons. Approximately 80% of all small-diameter (<27 µm) neurons from lumbar 1–6 DRGs that responded to TRPA1 agonists allyl isothiocyanate (AITC; 79%) or cinnamaldehyde (84%) were IB4-positive. Retrograde labeling via plantar hind paw injection of WGA-Alexafluor594 showed similarly that most (81%) cutaneous neurons responding to TRPA1 agonists were IB4-positive. Additionally, we cultured DRG neurons from a novel CGRP-GFP mouse where GFP expression is driven by the CGRPα promoter, enabling identification of CGRP-expressing live neurons. Interestingly, 78% of TRPA1-responsive neurons were CGRP-negative. Co-labeling with IB4 revealed that the majority (66%) of TRPA1 agonist responders were IB4-positive but CGRP-negative. Among TRPA1-null DRGs, few small neurons (2–4%) responded to either TRPA1 agonist, indicating that both cinnamaldehyde and AITC specifically target TRPA1. Additionally, few large neurons (≥27 µm diameter) responded to AITC (6%) or cinnamaldehyde (4%), confirming that most large-diameter somata lack functional TRPA1. Comparison of mouse and rat DRGs showed that the majority of TRPA1-responsive neurons in both species were IB4-positive. Together, these data demonstrate that TRPA1 is functionally

  16. TRPA1 is functionally expressed primarily by IB4-binding, non-peptidergic mouse and rat sensory neurons.

    PubMed

    Barabas, Marie E; Kossyreva, Elena A; Stucky, Cheryl L

    2012-01-01

    Subpopulations of somatosensory neurons are characterized by functional properties and expression of receptor proteins and surface markers. CGRP expression and IB4-binding are commonly used to define peptidergic and non-peptidergic subpopulations. TRPA1 is a polymodal, plasma membrane ion channel that contributes to mechanical and cold hypersensitivity during tissue injury, making it a key target for pain therapeutics. Some studies have shown that TRPA1 is predominantly expressed by peptidergic sensory neurons, but others indicate that TRPA1 is expressed extensively within non-peptidergic, IB4-binding neurons. We used FURA-2 calcium imaging to define the functional distribution of TRPA1 among peptidergic and non-peptidergic adult mouse (C57BL/6J) DRG neurons. Approximately 80% of all small-diameter (<27 µm) neurons from lumbar 1-6 DRGs that responded to TRPA1 agonists allyl isothiocyanate (AITC; 79%) or cinnamaldehyde (84%) were IB4-positive. Retrograde labeling via plantar hind paw injection of WGA-Alexafluor594 showed similarly that most (81%) cutaneous neurons responding to TRPA1 agonists were IB4-positive. Additionally, we cultured DRG neurons from a novel CGRP-GFP mouse where GFP expression is driven by the CGRPα promoter, enabling identification of CGRP-expressing live neurons. Interestingly, 78% of TRPA1-responsive neurons were CGRP-negative. Co-labeling with IB4 revealed that the majority (66%) of TRPA1 agonist responders were IB4-positive but CGRP-negative. Among TRPA1-null DRGs, few small neurons (2-4%) responded to either TRPA1 agonist, indicating that both cinnamaldehyde and AITC specifically target TRPA1. Additionally, few large neurons (≥27 µm diameter) responded to AITC (6%) or cinnamaldehyde (4%), confirming that most large-diameter somata lack functional TRPA1. Comparison of mouse and rat DRGs showed that the majority of TRPA1-responsive neurons in both species were IB4-positive. Together, these data demonstrate that TRPA1 is functionally

  17. Subcortical connections of normotopic and heterotopic neurons in sensory and motor cortices of the tish mutant rat.

    PubMed

    Schottler, F; Couture, D; Rao, A; Kahn, H; Lee, K S

    1998-05-25

    Orthograde and retrograde tracers were used to examine subcortical connections of neurons in the neurological mutant tish rat. This animal exhibits bilateral heterotopia similar to those observed in epileptic humans with subcortical band heterotopia. Terminal varicosities were labeled in the striatum, thalamus, brainstem, and spinal cord following injections of the anterograde tracer biotinylated dextran amine (BDA) into the heterotopic cortex. The general topography of corticothalamic projections was evaluated by injecting the retrograde tracer Fluoro-Gold (FG) into ventral thalamic nuclei. Retrograde labeling of small-to-medium sized neurons was observed in layer VI of topographically restricted portions of the normotopic cortex. Similar appearing cells were labeled in the neighboring portions of the underlying heterotopia; however, these neurons did not display characteristic lamination or radial orientation. Thalamocortical terminals labeled by injecting BDA into the ventroposterolateral nucleus (VPL) were observed primarily in layer IV of the medial aspect of the normotopic somatosensory cortex. In contrast, a radial column of terminals was present in the underlying heterotopia. Typical barrel labeling was found in the lateral aspect of the normotopic somatosensory cortex after injecting the ventroposteromedial nucleus (VPM), whereas more diffuse patches of labeling were observed in the underlying heterotopia. Heterotopic neurons in the tish cortex, thus, exhibit characteristic features of subcortical connectivity. Both normotopic and heterotopic neurons in the tish brain project to appropriate subcortical sites and establish bidirectional topographic connections with the thalamus. These results suggest that primary sensory-motor information is represented in a parallel manner in the normotopic and heterotopic cortices of the tish rat.

  18. Sensory neurons signal for an increase in rat gastric mucosal blood flow in the face of pending acid injury.

    PubMed

    Holzer, P; Livingston, E H; Guth, P H

    1991-08-01

    Disruption of the gastric mucosal barrier is quickly followed by an increase in gastric mucosal blood flow, which is thought to be a defensive reaction to prevent further injury. This study examined how this increase in blood flow is brought about. When the stomach of urethane-anesthetized rats was perfused with 0.15N HCl, disruption of the gastric mucosal barrier with 15% ethanol increased the disappearance of acid from the gastric lumen and enhanced gastric mucosal blood flow. This increase in blood flow was blocked by local arterial infusion of tetrodotoxin (60 ng/min) to the stomach and by chemical ablation of capsaicin-sensitive sensory neurons. Inhibition of the blood flow increase was associated with exaggeration of gross and histological injury to the mucosa. IV injection of atropine (0.2 mg/kg) or pyrilamine (2 mg/kg) did not affect blood flow increase in response to barrier disruption, whereas morphine injection (2 mg/kg) inhibited it. The current findings show that the increase in gastric mucosal blood flow that follows disruption of the gastric mucosal barrier in the presence of acid is mediated by sensory neurons that seem to monitor acid back-diffusion and in turn signal for a protective increase in blood flow.

  19. Gastrodin Inhibits Allodynia and Hyperalgesia in Painful Diabetic Neuropathy Rats by Decreasing Excitability of Nociceptive Primary Sensory Neurons

    PubMed Central

    Ye, Xin; Han, Wen-Juan; Wang, Wen-Ting; Luo, Ceng; Hu, San-Jue

    2012-01-01

    Painful diabetic neuropathy (PDN) is a common complication of diabetes mellitus and adversely affects the patients’ quality of life. Evidence has accumulated that PDN is associated with hyperexcitability of peripheral nociceptive primary sensory neurons. However, the precise cellular mechanism underlying PDN remains elusive. This may result in the lacking of effective therapies for the treatment of PDN. The phenolic glucoside, gastrodin, which is a main constituent of the Chinese herbal medicine Gastrodia elata Blume, has been widely used as an anticonvulsant, sedative, and analgesic since ancient times. However, the cellular mechanisms underlying its analgesic actions are not well understood. By utilizing a combination of behavioral surveys and electrophysiological recordings, the present study investigated the role of gastrodin in an experimental rat model of STZ-induced PDN and to further explore the underlying cellular mechanisms. Intraperitoneal administration of gastrodin effectively attenuated both the mechanical allodynia and thermal hyperalgesia induced by STZ injection. Whole-cell patch clamp recordings were obtained from nociceptive, capsaicin-sensitive small diameter neurons of the intact dorsal root ganglion (DRG). Recordings from diabetic rats revealed that the abnormal hyperexcitability of neurons was greatly abolished by application of GAS. To determine which currents were involved in the antinociceptive action of gastrodin, we examined the effects of gastrodin on transient sodium currents (INaT) and potassium currents in diabetic small DRG neurons. Diabetes caused a prominent enhancement of INaT and a decrease of potassium currents, especially slowly inactivating potassium currents (IAS); these effects were completely reversed by GAS in a dose-dependent manner. Furthermore, changes in activation and inactivation kinetics of INaT and total potassium current as well as IAS currents induced by STZ were normalized by GAS. This study provides a clear

  20. Expression of Semaphorins, Neuropilins, VEGF, and Tenascins in Rat and Human Primary Sensory Neurons after a Dorsal Root Injury

    PubMed Central

    Lindholm, Tomas; Risling, Mårten; Carlstedt, Thomas; Hammarberg, Henrik; Wallquist, Wilhelm; Cullheim, Staffan; Sköld, Mattias K.

    2017-01-01

    Dorsal root injury is a situation not expected to be followed by a strong regenerative growth, or growth of the injured axon into the central nervous system of the spinal cord, if the central axon of the dorsal root is injured but of strong regeneration if subjected to injury to the peripherally projecting axons. The clinical consequence of axonal injury is loss of sensation and may also lead to neuropathic pain. In this study, we have used in situ hybridization to examine the distribution of mRNAs for the neural guidance molecules semaphorin 3A (SEMA3A), semaphorin 3F (SEMA3F), and semaphorin 4F (SEMA4F), their receptors neuropilin 1 (NP1) and neuropilin 2 (NP2) but also for the neuropilin ligand vascular endothelial growth factor (VEGF) and Tenascin J1, an extracellular matrix molecule involved in axonal guidance, in rat dorsal root ganglia (DRG) after a unilateral dorsal rhizotomy (DRT) or sciatic nerve transcetion (SNT). The studied survival times were 1–365 days. The different forms of mRNAs were unevenly distributed between the different size classes of sensory nerve cells. The results show that mRNA for SEMA3A was diminished after trauma to the sensory nerve roots in rats. The SEMA3A receptor NP1, and SEMA3F receptor NP2, was significantly upregulated in the DRG neurons after DRT and SNT. SEMA4F was upregulated after a SNT. The expression of mRNA for VEGF in DRG neurons after DRT showed a significant upregulation that was high even a year after the injuries. These data suggest a role for the semaphorins, neuropilins, VEGF, and J1 in the reactions after dorsal root lesions. PMID:28270793

  1. Capsaicin-sensitive sensory neurons are involved in bicarbonate secretion induced by lansoprazole, a proton pump inhibitor, in rats.

    PubMed

    Inada, I; Satoh, H

    1996-04-01

    Lansoprazole, a proton pump inhibitor, exerts prominent antiulcer activity via both antisecretory and mucosal protective actions. Although the antisecretory action has been explained by inactivation of (H+, K+)-ATPase in parietal cells, the mode of mucosal protective action remains to be elucidated. In the present study, the effect of lansoprazole on duodenal bicarbonate secretion was studied in anesthetized rats to clarify the mode of the mucosal protective action. Lansoprazole (0.1 mM) applied topically to the duodenum significantly (P < 0.01) increased bicarbonate secretion by 0.36 +/- 0.11 microeq/15 min (21 +/- 5%) compared with the value in the vehicle control. Topical administration of capsaicin (10 mg/ml) in the duodenum and intravenous infusion of vasoactive intestinal peptide (10 micrograms/kg/hr) increased bicarbonate secretion. Five-minute perfusion of the duodenal loop with 100 mM HCl increased bicarbonate secretion. Administration of lansoprazole (0.3 and 1 mg/kg, intravenously) 60 min before luminal acidification enhanced the acid-induced bicarbonate secretion dose-dependently and significantly (P < 0.01). In the capsaicin-pretreated rats, the effects of lansoprazole on basal and acid-induced bicarbonate secretion were significantly (P < 0.05) decreased compared with that of control group. These results indicate that lansoprazole increases basal and acid-induced bicarbonate secretion in the duodenum in rats and that capsaicin-sensitive sensory neurons may be involved in the mode of action for these effects.

  2. Temperature coefficient of membrane currents induced by noxious heat in sensory neurones in the rat

    PubMed Central

    Vyklický, L; Vlachová, V; Vitásková, Z; Dittert, I; Kabát, M; Orkand, R K

    1999-01-01

    Membrane currents induced by noxious heat (Iheat) were studied in cultured dorsal root ganglion (DRG) neurones from newborn rats using ramps of increasing temperature of superfusing solutions. Iheat was observed in about 70 % of small (< 25 μm) DRG neurones. At -60 mV, Iheat exhibited a threshold at about 43 °C and reached its maximum, sometimes exceeding 1 nA, at 52 °C (716 ± 121 pA; n = 39). Iheat exhibited a strong temperature sensitivity (temperature coefficient over a 10 °C temperature range (Q10) = 17·8 ± 2·1, mean ± s.d., in the range 47-51 °C; n = 41), distinguishing it from the currents induced by capsaicin (1 μM), bradykinin (5 μM) and weak acid (pH 6·1 or 6·3), which exhibited Q10 values of 1·6-2·8 over the whole temperature range (23-52 °C). Repeated heat ramps resulted in a decrease of the maximum Iheat and the current was evoked at lower temperatures. A single ramp exceeding 57 °C resulted in an irreversible change in Iheat. In a subsequent trial, maximum Iheat was decreased to less than 50 %, its threshold was lowered to a temperature just above that in the bath and its maximum Q10 was markedly lower (5·6 ± 0·8; n = 8). DRG neurones that exhibited Iheat were sensitive to capsaicin. However, four capsaicin-sensitive neurones out of 41 were insensitive to noxious heat. There was no correlation between the amplitude of capsaicin-induced responses and Iheat. In the absence of extracellular Ca2+, Q10 for Iheat was lowered from 25·3 ± 7·5 to 4·2 ± 0·4 (n = 7) in the range 41-50 °C. The tachyphylaxis, however, was still observed. A high Q10 of Iheat suggests a profound, rapid and reversible change in a protein structure in the plasma membrane of heat-sensitive nociceptors. It is hypothesized that this protein complex possesses a high net free energy of stabilization (possibly due to ionic bonds) and undergoes disassembly when exposed to noxious heat. The liberated components activate distinct cationic channels to generate Iheat

  3. Ca2+ efflux mechanisms following depolarization evoked calcium transients in cultured rat sensory neurones.

    PubMed Central

    Benham, C D; Evans, M L; McBain, C J

    1992-01-01

    1. We have used a combination of microfluorimetry and patch-clamp techniques to investigate cytoplasmic Ca2+ ([Ca2+]i) buffering in response to physiological Ca2+ loads in neurones cultured from the dorsal root ganglia of the rat. 2. In cells loaded with Indo-1 AM and using high resistance microelectrodes to initiate and record action potentials, single action potentials were associated with a measurable rise in [Ca2+]i. Short trains of action potentials evoked [Ca2+]i transients with monoexponential recovery rates with time constants of around 5 s. 3. Similar Ca2+ buffering properties were seen in cells perfused with patch-clamp pipettes in the whole-cell recording mode suggesting that the slow (seconds) Ca2+ buffering properties were not seriously perturbed by the recording technique. 4. In cells held under voltage clamp, reversal of the Na(+)-Ca2+ exchanger driving force had a small but significant effect on the rate of Ca2+ removal. 5. Increasing extracellular pH or adding vanadate (200 microM) to the internal solution dramatically slowed the rate of recovery. Addition of calmidazolium to the pipette solution also produced a significant but much less dramatic slowing of Ca2+ efflux. 6. The results demonstrate that the activity of a plasmalemmal Ca(2+)-ATPase is important for the removal of somatic Ca2+ loads of a similar amplitude to those generated by the firing of a few action potentials. Images Fig. 7 PMID:1484362

  4. Ca2+ efflux mechanisms following depolarization evoked calcium transients in cultured rat sensory neurones.

    PubMed

    Benham, C D; Evans, M L; McBain, C J

    1992-09-01

    1. We have used a combination of microfluorimetry and patch-clamp techniques to investigate cytoplasmic Ca2+ ([Ca2+]i) buffering in response to physiological Ca2+ loads in neurones cultured from the dorsal root ganglia of the rat. 2. In cells loaded with Indo-1 AM and using high resistance microelectrodes to initiate and record action potentials, single action potentials were associated with a measurable rise in [Ca2+]i. Short trains of action potentials evoked [Ca2+]i transients with monoexponential recovery rates with time constants of around 5 s. 3. Similar Ca2+ buffering properties were seen in cells perfused with patch-clamp pipettes in the whole-cell recording mode suggesting that the slow (seconds) Ca2+ buffering properties were not seriously perturbed by the recording technique. 4. In cells held under voltage clamp, reversal of the Na(+)-Ca2+ exchanger driving force had a small but significant effect on the rate of Ca2+ removal. 5. Increasing extracellular pH or adding vanadate (200 microM) to the internal solution dramatically slowed the rate of recovery. Addition of calmidazolium to the pipette solution also produced a significant but much less dramatic slowing of Ca2+ efflux. 6. The results demonstrate that the activity of a plasmalemmal Ca(2+)-ATPase is important for the removal of somatic Ca2+ loads of a similar amplitude to those generated by the firing of a few action potentials.

  5. Selective decrease of small sensory neurons in lumbar dorsal root ganglia labeled with horseradish peroxidase after ND:YAG laser irradiation of the tibial nerve in the rat

    SciTech Connect

    Wesselmann, U.; Lin, S.F.; Rymer, W.Z. )

    1991-02-01

    Recent electrophysiological evidence indicates that Q-switched Nd:YAG laser irradiation might have selective effects on neural impulse transmission in small slow conducting sensory nerve fibers as compared to large diameter afferents. In an attempt to clarify the ultimate fate of sensory neurons after laser application to their peripheral axons, we have used horseradish peroxidase (HRP) as a cell marker to retrogradely label sensory neurons innervating the distal hindlimb in the rat. Pulsed Nd:YAG laser light was applied to the tibial nerve at pulse energies of 70 or 80 mJ/pulse for 5 min in experimental rats. Seven days later HRP was applied to the left (laser-treated) and to the contralateral (untreated) tibial nerve proximal to the site of laser irradiation. In control animals the numbers of HRP-labeled dorsal root ganglion cells were not significantly different between the right and the left side. In contrast, after previous laser irradiation labeling was always less on the laser-treated side (2183 +/- 513 cells, mean +/- SEM) as compared to the untreated side (3937 +/- 225). Analysis of the dimensions of labeled cells suggested that the reduction of labeled cells on the laser-treated side was mainly due to a deficit in small sensory neurons. Since the conduction velocity of nerve fibers is related to the size of their somata, our histological data imply that laser light selectively affects retrograde transport mechanisms for HRP in slow conducting sensory nerve fibers.

  6. Stomatin and sensory neuron mechanotransduction.

    PubMed

    Martinez-Salgado, Carlos; Benckendorff, Anne G; Chiang, Li-Yang; Wang, Rui; Milenkovic, Nevena; Wetzel, Christiane; Hu, Jing; Stucky, Cheryl L; Parra, Marilyn G; Mohandas, Narla; Lewin, Gary R

    2007-12-01

    Somatic sensory neurons of the dorsal root ganglia are necessary for a large part of our mechanosensory experience. However, we only have a good knowledge of the molecules required for mechanotransduction in simple invertebrates such as the nematode Caenorhabiditis elegans. In C. elegans, a number of so-called mec genes have been isolated that are required for the transduction of body touch. One such gene, mec-2 codes for an integral membrane protein of the stomatin family, a large group of genes with a stomatin homology domain. Using stomatin null mutant mice, we have tested the hypothesis that the founding member of this family, stomatin might play a role in the transduction of mechanical stimuli by primary sensory neurons. We used the in vitro mouse skin nerve preparation to record from a large population of low- and high-threshold mechanoreceptors with myelinated A-fiber (n = 553) and unmyelinated C-fiber (n = 157) axons. One subtype of mechanoreceptor, the d-hair receptor, which is a rapidly adapting mechanoreceptor, had reduced sensitivity to mechanical stimulation in the absence of stomatin. Other cutaneous mechanoreceptors, including nociceptive C-fibers were not affected by the absence of a functional stomatin protein. Patch-clamp analysis of presumptive D-hair receptor mechanoreceptive neurons, which were identified by a characteristic rosette morphology in culture, showed no change in membrane excitability in the absence of the stomatin protein. We conclude that stomatin is required for normal mechanotransduction in a subpopulation of vertebrate sensory neurons.

  7. Calcium channel currents and their inhibition by (-)-baclofen in rat sensory neurones: modulation by guanine nucleotides.

    PubMed Central

    Dolphin, A C; Scott, R H

    1987-01-01

    1. The effect of intracellular application of the hydrolysis-resistant GTP and GDP analogues, guanosine 5'-O-3-thiotriphosphate (GTP-gamma-S), and guanosine 5'-O-2-thiodiphosphate (GDP-beta-S) has been examined on voltage-activated calcium-channel currents and the ability of the gamma-aminobutyric acid B agonist baclofen to inhibit them, in cultured rat dorsal root ganglion (d.r.g.) neurones. 2. Under control conditions, the calcium-channel current, recorded using the whole-cell patch technique with Ba2+ rather than Ca2+ as the permeant divalent cation, consists of an inactivating and a sustained current. In the presence of 500 microM-GTP-gamma-S included in the patch pipette, the calcium-channel current was activated more slowly and was largely non-inactivating during the 100 ms depolarization voltage step. The effects of GTP-gamma-S were abolished by pre-treatment of cells with pertussis toxin. 3. The calcium-channel current recorded in the presence of 500 microM-GDP-beta-S had a more marked transient component than the control calcium-channel current. The proportion of transient calcium-channel current in the presence of GDP-beta-S was not reduced in Na+-free medium. 4. No statistically significant effects of GTP-gamma-S and GDP-beta-S were observed on the calcium-activated potassium current IK(Ca), the transient outward potassium current activated in Ca2+-free medium, or on the inwardly rectifying current (Ih) activated by hyperpolarization. 5. GTP-gamma-S increased the ability of baclofen to inhibit calcium-channel currents, whereas this was decreased by GDP-beta-S and by pre-treatment of cells with pertussis toxin. The half-maximal effective dose (EC50) for baclofen was 2 microM in the presence of GTP-gamma-S, 15 microM for control and 50 microM in the presence of GDP-beta-S. Comparable results were obtained using a single concentration of the adenosine agonist 2-chloroadenosine (2-CA, 0.05 microM) to inhibit calcium-channel currents; its effect was

  8. Angiotensin II type 2 receptor (AT2 R) localization and antagonist-mediated inhibition of capsaicin responses and neurite outgrowth in human and rat sensory neurons.

    PubMed

    Anand, U; Facer, P; Yiangou, Y; Sinisi, M; Fox, M; McCarthy, T; Bountra, C; Korchev, Y E; Anand, P

    2013-08-01

    The angiotensin II (AngII) receptor subtype 2 (AT2 R) is expressed in sensory neurons and may play a role in nociception and neuronal regeneration. We used immunostaining with characterized antibodies to study the localization of AT2 R in cultured human and rat dorsal root ganglion (DRG) neurons and a range of human tissues. The effects of AngII and AT2 R antagonist EMA401 on capsaicin responses in cultured human and rat (DRG) neurons were measured with calcium imaging, on neurite length and density with Gap43 immunostaining, and on cyclic adenosine monophosphate (cAMP) expression using immunofluorescence. AT2 R expression was localized in small-/medium-sized cultured neurons of human and rat DRG. Treatment with the AT2 R antagonist EMA401 resulted in dose-related functional inhibition of capsaicin responses (IC50  = 10 nmol/L), which was reversed by 8-bromo-cAMP, and reduced neurite length and density; AngII treatment significantly enhanced capsaicin responses, cAMP levels and neurite outgrowth. The AT1 R antagonist losartan had no effect on capsaicin responses. AT2 R was localized in sensory neurons of human DRG, and nerve fibres in peripheral nerves, skin, urinary bladder and bowel. A majority sub-population (60%) of small-/medium-diameter neuronal cells were immunopositive in both control post-mortem and avulsion-injured human DRG; some very small neurons appeared to be intensely immunoreactive, with TRPV1 co-localization. While AT2 R levels were reduced in human limb peripheral nerve segments proximal to injury, they were preserved in painful neuromas. AT2 R antagonists could be particularly useful in the treatment of chronic pain and hypersensitivity associated with abnormal nerve sprouting. © 2012 European Federation of International Association for the Study of Pain Chapters.

  9. Angiotensin II type 2 receptor (AT2R) localization and antagonist-mediated inhibition of capsaicin responses and neurite outgrowth in human and rat sensory neurons

    PubMed Central

    Anand, U; Facer, P; Yiangou, Y; Sinisi, M; Fox, M; McCarthy, T; Bountra, C; Korchev, YE; Anand, P

    2013-01-01

    Background The angiotensin II (AngII) receptor subtype 2 (AT2R) is expressed in sensory neurons and may play a role in nociception and neuronal regeneration. Methods We used immunostaining with characterized antibodies to study the localization of AT2R in cultured human and rat dorsal root ganglion (DRG) neurons and a range of human tissues. The effects of AngII and AT2R antagonist EMA401 on capsaicin responses in cultured human and rat (DRG) neurons were measured with calcium imaging, on neurite length and density with Gap43 immunostaining, and on cyclic adenosine monophosphate (cAMP) expression using immunofluorescence. Results AT2R expression was localized in small-/medium-sized cultured neurons of human and rat DRG. Treatment with the AT2R antagonist EMA401 resulted in dose-related functional inhibition of capsaicin responses (IC50 = 10 nmol/L), which was reversed by 8-bromo-cAMP, and reduced neurite length and density; AngII treatment significantly enhanced capsaicin responses, cAMP levels and neurite outgrowth. The AT1R antagonist losartan had no effect on capsaicin responses. AT2R was localized in sensory neurons of human DRG, and nerve fibres in peripheral nerves, skin, urinary bladder and bowel. A majority sub-population (60%) of small-/medium-diameter neuronal cells were immunopositive in both control post-mortem and avulsion-injured human DRG; some very small neurons appeared to be intensely immunoreactive, with TRPV1 co-localization. While AT2R levels were reduced in human limb peripheral nerve segments proximal to injury, they were preserved in painful neuromas. Conclusions AT2R antagonists could be particularly useful in the treatment of chronic pain and hypersensitivity associated with abnormal nerve sprouting. PMID:23255326

  10. Ca2+ influx in resting rat sensory neurones that regulates and is regulated by ryanodine-sensitive Ca2+ stores

    PubMed Central

    Usachev, Yuriy M; Thayer, Stanley A

    1999-01-01

    Store-operated, voltage-independent Ca2+ channels are activated by depletion of intracellular Ca2+ stores and mediate Ca2+ influx into non-excitable cells at resting membrane potential. We used microfluorimetry, patch-clamp and Mn2+-quench techniques to explore the possibility that a similar mechanism exists in rat dorsal root ganglion (DRG) neurones in primary culture. Following caffeine-induced depletion, ryanodine-sensitive Ca2+ stores refilled with Ca2+ at resting membrane potential. The refilling process required extracellular Ca2+, was blocked by 2 mM Ni2+, and was facilitated by membrane hyperpolarization from −55 to −80 mV, indicating a key role for Ca2+ influx. This influx of Ca2+ was not affected by the voltage-operated Ca2+ channel (VOCC) antagonists nicardipine (10 μM), nimodipine (10 μm) or ω-grammotoxin SIA (1 μm). When ryanodine-sensitive Ca2+ stores were depleted in Ca2+-free media, a return to 2 mM external Ca2+ resulted in a pronounced [Ca2+]i overshoot, indicating an increased permeability to Ca2+. Depletion of Ca2+ stores also produced a 2-fold increase in the rate of Mn2+ influx. The [Ca2+]i overshoot and Mn2+ entry were both inhibited by Ni2+, but not by VOCC antagonists. Caffeine induced periodic Ca2+ release from, and reuptake into, ryanodine-sensitive stores. The [Ca2+]i oscillations were arrested by removal of extracellular Ca2+ or by addition of Ni2+, but they were not affected by VOCC antagonists. Hyperpolarization increased the frequency of this rhythmic activity. These data suggest the presence of a Ca2+ entry pathway in mammalian sensory neurones that is distinct from VOCCs and is regulated by ryanodine-sensitive Ca2+ stores. This pathway participates in refilling intracellular Ca2+ stores and maintaining [Ca2+]i oscillations and thus controls the balance between intra- and extracellular Ca2+ reservoirs in resting DRG neurones. PMID:10432343

  11. Calcitonin gene-related peptide immunoreactive sensory neurons in the vagal and glossopharyngeal ganglia innervating the larynx of the rat.

    PubMed

    Hayakawa, Tetsu; Kuwahara-Otani, Sachi; Maeda, Seishi; Tanaka, Koichi; Seki, Makoto

    2014-01-01

    We have examined whether calcitonin gene-related peptide-immunoreactive (CGRP-ir) neurons in the vagal and glossopharyngeal ganglia innervate the larynx. Many CGRP-ir neurons were located mostly in the superior glossopharyngeal-jugular ganglion complex that was fused the superior glossopharyngeal ganglion and the jugular ganglion in the cranial cavity. When Fluorogold was applied to the cut end of the superior laryngeal nerve (SLN) or the recurrent laryngeal nerve (RLN), many Fluorogold-labeled neurons were found in the superior glossopharyngeal-jugular ganglion complex and the nodose ganglion. Double-labeling for CGRP and Fluorogold showed that about 80% of Fluorogold-labeled neurons in the superior glossopharyngeal-jugular ganglion complex expressed CGRP-like immunoreactivity in the case of application to the SLN, and about 50% of Fluorogold-labeled neurons expressed CGRP-like immunoreactivity in the case of the RLN. Only a few double-labeled neurons were found in the nodose ganglion. The number of the Fluorogold-labeled neurons and double-labeled neurons in the superior glossopharyngeal-jugular ganglion complex in the case of the SLN was larger than that in the case of the RLN. These results indicate that sensory information from the larynx might be conveyed by many CGRP-ir neurons located in the superior glossopharyngeal-jugular ganglion complex by way of the SLN and the RLN.

  12. Thiamine, pyridoxine, cyanocobalamin and their combination inhibit thermal, but not mechanical hyperalgesia in rats with primary sensory neuron injury.

    PubMed

    Wang, Zheng-Bei; Gan, Qiang; Rupert, Ronald L; Zeng, Yin-Ming; Song, Xue-Jun

    2005-03-01

    Neuropathic pain after nerve injury is severe and intractable, and current drugs and nondrug therapies offer substantial pain relief to no more than half of affected patients. The present study investigated the analgesic roles of the B vitamins thiamine (B1), pyridoxine (B6) and cyanocobalamin (B12) in rats with neuropathic pain caused by spinal ganglia compression (CCD) or loose ligation of the sciatic nerve (CCI). Thermal hyperalgesia was determined by a significantly shortened latency of foot withdrawal to radiant heat, and mechanical hyperalgesia was determined by a significantly decreased threshold of foot withdrawal to von Frey filaments stimulation of the plantar surface of hindpaw. Results showed that (1) intraperitoneal injection of B1 (5, 10, 33 and 100 mg/kg), B6 (33 and 100 mg/kg) or B12 (0.5 and 2 mg/kg) significantly reduced thermal hyperalgesia; (2) the combination of B1, B6 and B12 synergistically inhibited thermal hyperalgesia; (3) repetitive administration of vitamin B complex (containing B1/B6/B12 33/33/0.5 mg/kg, for 1 and 2 wk) produced long-term inhibition of thermal hyperalgesia; and (4) B vitamins did not affect mechanical hyperalgesia or normal pain sensation, and exhibited similar effects on CCD and CCI induced-hyperalgesia. The present studies demonstrate effects of B vitamins on pain and hyperalgesia following primary sensory neurons injury, and suggest the possible clinical utility of B vitamins in the treatment of neuropathic painful conditions following injury, inflammation, degeneration or other disorders in the nervous systems in human beings.

  13. B1 bradykinin receptors and sensory neurones.

    PubMed Central

    Davis, C. L.; Naeem, S.; Phagoo, S. B.; Campbell, E. A.; Urban, L.; Burgess, G. M.

    1996-01-01

    1. The location of the B1 bradykinin receptors involved in inflammatory hyperalgesia was investigated. 2. No specific binding of the B1 bradykinin receptor ligand [3H]-des-Arg10-kallidin was detected in primary cultures of rat dorsal root ganglion neurones, even after treatment with interleukin-1 beta (100 iu ml-1). 3. In dorsal root ganglion neurones, activation of B2 bradykinin receptors stimulated polyphosphoinositidase C. In contrast, B1 bradykinin receptor agonists (des-Arg9-bradykinin up to 10 microM and des-Arg10-kallidin up to 1 microM) failed to activate polyphosphoinositidase C, even in neurones that had been treated with interleukin-1 beta (100 iu ml-1), prostaglandin E2 (1 microM) or prostaglandin I2 (1 microM). 4. Dorsal root ganglion neurones removed from rats (both neonatal and 14 days old) that had been pretreated with inflammatory mediators (Freund's complete adjuvant, or carrageenan) failed to respond to B1 bradykinin receptor selective agonists (des-Arg9-bradykinin up to 10 microM and des-Arg10-kallidin up to 1 microM). 5. Bradykinin (25 nM to 300 nM) evoked ventral root responses when applied to peripheral receptive fields or central terminals of primary afferents in the neonatal rat spinal cord and tail preparation. In contrast, des-Arg9-bradykinin (50 nM to 500 nM) failed to evoke ventral root depolarizations in either control rats or in animals that developed inflammation following ultraviolet irradiation of the tail skin. 6. The results of the present study imply that the B1 bradykinin receptors that contribute to hypersensitivity in models of persistent inflammatory hyperalgesia are located on cells other than sensory neurones where they may be responsible for releasing mediators that sensitize or activate the nociceptors. PMID:8832074

  14. Fos protein-like immunoreactive neurons induced by electrical stimulation in the trigeminal sensory nuclear complex of rats with chronically injured peripheral nerve.

    PubMed

    Fujisawa, Naoko; Terayama, Ryuji; Yamaguchi, Daisuke; Omura, Shinji; Yamashiro, Takashi; Sugimoto, Tomosada

    2012-06-01

    The rat trigeminal sensory nuclear complex (TSNC) was examined for Fos protein-like immunoreactive (Fos-LI) neurons induced by electrical stimulation (ES) of the lingual nerve (LN) at 2 weeks after injury to the LN or the inferior alveolar nerve (IAN). Intensity-dependent increase in the number of Fos-LI neurons was observed in the subnucleus oralis (Vo) and caudalis (Vc) of the spinal trigeminal tract nucleus irrespective of nerve injury. The number of Fos-LI neurons induced by ES of the chronically injured LN at A-fiber intensity (0.1 mA) was significantly increased in the Vo but not the Vc. On the other hand, in rats with chronically injured IAN, the number of Fos-LI neurons induced by ES of the LN at C-fiber intensity (10 mA) was significantly increased in the Vc but not the Vo. These results indicated that injury of a nerve innervating intraoral structures increased the c-Fos response of Vo neurons to A-fiber intensity ES of the injured nerve. A similar nerve injury enhanced the c-Fos response of Vc neurons to C-fiber intensity ES of a spared uninjured nerve innervating an intraoral territory neighboring that of the injured nerve. The present result show that nerve injury causes differential effects on c-Fos expression in the Vo and Vc, which may explain complexity of neuropathic pain symptoms in clinical cases.

  15. Response properties of periodontal mechanosensitive neurones in the rat trigeminal sensory complex projecting to the posteromedial ventral nucleus of the thalamus.

    PubMed

    Tabata, T; Takahashi, Y; Hayashi, H

    2001-10-01

    Unitary discharges from periodontal mechanosensitive (PM) neurones responding to mechanical stimulation of the tooth were recorded from the trigeminal sensory complex in the rat brainstem. Of the PM units recorded, 22% were activated by antidromic stimulation of the contralateral (20%) or ipsilateral (2%) posteromedial ventral nucleus of the thalamus. Although thalamic-projecting neurones were recorded extensively throughout the trigeminal sensory complex, they originated most often in the region from the caudal main sensory nucleus to the rostral subnucleus oralis of the trigeminal spinal tract nucleus. The response latencies of the rostral nucleus units to orthodromic stimulation of peripheral receptive fields and antidromic stimulation of the thalamus were significantly shorter than those of the caudal nucleus units. More than half were single-tooth units originating from incisor teeth. They responded continuously when pressure was applied to the tooth. The magnitude of the response varied with the direction of the stimulus. Maximal responses were obtained when the stimulus was applied labiolingually or vice versa. The threshold for mechanical stimulation of the tooth was less than 0.05 N. The rostrocaudal distribution and response properties of thalamic-projecting PM neurones were very similar to those of non-thalamic-projecting PM units that were not activated by antidromic stimulation of the thalamus.

  16. Distribution and changes with age of calcitonin gene-related peptide- and substance P-immunoreactive nerves of the rat urinary bladder and lumbosacral sensory neurons.

    PubMed

    Mohammed, H A; Santer, R M

    2002-12-01

    In the distal parts of the urinary tract, nerves containing calcitonin gene-related peptide (CGRP) or substance P (SP) are sensory with their cell bodies located in lumbosacral dorsal root ganglia. These two neuropeptides are recognised as being present in pelvic sensory nerves, and may be involved in the mediation of pain, stretch and/or vasodilatation. We have used indirect immunohistochemical techniques to examine the distribution and regional variation of nerves immunoreactive (-ir) for CGRP and SP in the urinary bladder and in neurons in lumbosacral dorsal root ganglia (L1-L2 & L6-S1) of young adult (3 months) and aged (24 months) male rats. Semi-quantitative estimations of nerve densities were made for CGRP-ir and SP-ir fibres innervating the dome, body and base of the urinary bladder. Quantitative studies were also used to examine the effects of age on the percentage of dorsal root ganglion neurons immunoreactive for CGRP and SP. There were very few immunoreactive axons in the dome and the overall density of innervation increased progressively towards the base of the bladder. The density of innervation in the aged rats revealed a slight reduction in CGRP and SP innervation of the detrusor muscle but was otherwise comparable to the young group. However, immunostaining of the lumbosacral dorsal root ganglia revealed that the percentage of CGRP- and SP-ir neuronal profiles showed a significant (P < 0.05) reduction from (mean +/- S.D) 44.5 +/- 2; 23.3 +/- 2 in young adult to 25.0 +/- 2.9; 14.8 +/- 1.6 in aged rats, respectively. These findings suggest that the involvement of CGRP and SP in urinary bladder innervation is relatively unchanged in old age, but their expression in dorsal root ganglion neurons is affected by age. The afferent micturition pathway from the pelvic region via these lumbosacral ganglia may be perturbed as a result.

  17. Immediate and delayed potentiating effects of tumor necrosis factor-α on TRPV1 sensitivity of rat vagal pulmonary sensory neurons.

    PubMed

    Hsu, Chun-Chun; Lin, You Shuei; Lin, Ruei-Lung; Lee, Lu-Yuan

    2017-08-01

    We studied acute effects of tumor necrosis factor-α (TNFα) on the sensitivity of isolated rat vagal pulmonary sensory neurons. Our results showed the following. First, a brief pretreatment with a low dose of TNFα (1.44 nM, 9 min) enhanced the sensitivity of transient receptor potential vanilloid type 1 (TRPV1) receptors in these neurons in two distinct phases: the inward current evoked by capsaicin was amplified (Δ = 247%) immediately following the TNFα pretreatment, which gradually declined toward control and then increased again reaching another peak (Δ = 384%) after 60-90 min. Second, the immediate phase of this potentiating effect of TNFα was completely abolished by a pretreatment with a selective cyclooxygenase-2 (COX-2) inhibitor, NS-398, whereas the delayed potentiation was only partially attenuated. Third, in sharp contrast, TNFα did not generate any potentiating effect on the responses to non-TRPV1 chemical activators of these neurons. Fourth, the selectivity of the TNFα action on TRPV1 was further illustrated by the responses to acid (pH 6.0); TNFα did not affect the rapid transient current mediated by acid-sensing ion channels but significantly augmented the slow sustained current mediated by TRPV1 in the same neurons. Fifth, in anesthetized rats, a similar pattern of acute sensitizing effects of TNFα on pulmonary C-fiber afferents and the involvement of COX-2 were also clearly shown. In conclusion, a brief pretreatment with TNFα induced both immediate and delayed potentiating effects on the TRPV1 sensitivity in pulmonary sensory neurons, and the production of COX-2 arachidonic acid metabolites plays a major role in the immediate sensitizing effect of TNFα. Copyright © 2017 the American Physiological Society.

  18. Distribution and changes with age of nitric oxide synthase-immunoreactive nerves of the rat urinary bladder, ureter and in lumbosacral sensory neurons.

    PubMed

    Mohammed, H; Santer, R M

    2001-07-01

    In the distal parts of the urinary tract, nerves containing nitric oxide (NO) are either postganglionic parasympathetic nerves, with cell bodies in the major pelvic ganglia, or sensory nerves with cell bodies in the lumbosacral dorsal root ganglia. We have used indirect immunohistochemical techniques to examine the distribution and regional variation of nerves immunoreactive for neuronal nitric oxide synthase (NOS) in the urinary bladder, distal ureter and in neurons in lumbosacral dorsal root ganglia (L1-L2 & L6-S1) of young adult (3 months) and aged (24 months) male rats. Semi-quantitative estimations of nerve densities were made of NOS fibres innervating the dome, body and base of the urinary bladder and distal ureter. Quantitative studies were also used to examine the effects of age on the percentage of dorsal root ganglion neurons immunoreactive for NOS. The dome and the body regions, in both age groups, contained no NOS-immunoreactive axons. The bladder base and distal ureter in young adults showed sparse to moderate numbers of fibres immunoreactive to NOS within the urothelium and in the subepithelium and muscle coat. In the aged rat there were slight reductions in the densities of NOS-immunoreactive nerves in all three regions. In the lumbosacral dorsal root ganglia, the percentage of NOS-immunoreactive neuronal profiles showed a significant reduction from 4.6 +/- 0.2% in young adult to 2.7 +/- 0.2% (means +/- S.E.M) in aged rats. These findings suggest that the effects of NO on the bladder and distal ureteric musculature and also its expression in dorsal root ganglion neurons are affected in aged rats and that the micturition reflex may be perturbed as a result.

  19. [Morphological transformation of sensory ganglion neurons and satellite cells].

    PubMed

    Matsuda, S; Kobayashi, N; Mominoki, K; Wakisaka, H; Mori, M; Murakami, S

    1998-12-01

    Sensory ganglion neurons in higher vertebrates are unique in that they are pseudounipolar with a single stem process that divides at some distance from the cell body into central and peripheral processes. In the early stages of development, these neurons are bipolar but later they became pseudounipolar. This developmental process of sensory ganglion neurons with satellite cells was examined by scanning electron microscopy following removal of connective tissue. This pseudo-unipolarization began earlier but proceeded at a slower rate in chick than in rat embryos. This difference may due to the difference found in the extent and intimacy of satellite cell investments in these two animals, which was due to the fact that sensory neurons undergo pseudo-unipolarization only in the presence of satellite cells in vitro. The neuronal perikaryal projections were observed by scanning electron microscopy after removal of connective tissue and satellite cells. Morphometric analysis reveal that perikaryal projections were more numerous on the surface of mature pseudounipolar neurons than on the surface of premature bipolar neurons, and that the number of projections increased as the neuronal cell bodies grew larger. This may support the hypothesis that perikaryal projections are structural devices for increasing the neuron-satellite interface and for improving the efficiency of metabolic exchange between these two cell types. These results suggest that satellite cells play an important role in neuronal maturation.

  20. Functional interactions between NMDA receptors and TRPV1 in trigeminal sensory neurons mediate mechanical hyperalgesia in the rat masseter muscle

    PubMed Central

    Lee, Jongseok; Saloman, Jami L.; Weiland, Gustave; Auh, Q-Schick; Chung, Man-Kyo; Ro, Jin Y.

    2012-01-01

    NMDA and TRPV1 receptors that are expressed in sensory neurons have been independently demonstrated to play important roles in peripheral pain mechanisms. In the present study, we investigated whether the two receptor-channel systems form a functional complex that provides the basis for the development of mechanical hyperalgesia. In the masseter muscle, direct application of NMDA induced a time dependent increase in mechanical sensitivity, which was significantly blocked when the muscle was pretreated with a specific TRPV1 antagonist, AMG9810. The NR1 subunit of the NMDA receptor and TRPV1 were co-expressed in 32% of masseter afferents in trigeminal ganglia (TG). Furthermore, NR1 and NR2B formed protein-protein complexes with TRPV1 in TG as demonstrated by co-immunoprecipitation experiments. Calcium imaging analyses further corroborated that NMDA and TRPV1 receptors functionally interact. In TG culture, application of NMDA resulted in phosphorylation of serine, but not threonine or tyrosine, residues of TRPV1 in a time course similar to that of the development of NMDA-induced mechanical hyperalgesia. The NMDA-induced phosphorylation was significantly attenuated by CaMKII and PKC inhibitors, but not by a PKA inhibitor. Consistent with the biochemical data, the NMDA-induced mechanical hyperalgesia was also effectively blocked when the muscle was pretreated with a CaMKII or PKC inhibitor. Thus, NMDA receptors and TRPV1 functionally interact via CaMKII and PKC signaling cascades and contribute to mechanical hyperalgesia. These data offer novel mechanisms by which two ligand-gated channels in sensory neurons interact and reinforce the notion that TRPV1 functions as a “signal integrator” under pathological conditions. PMID:22609428

  1. Sciatic nerve injury in adult rats causes distinct changes in the central projections of sensory neurons expressing different glial cell line-derived neurotrophic factor family receptors

    PubMed Central

    Keast, Janet R.; Forrest, Shelley L.; Osborne, Peregrine B.

    2010-01-01

    Most small unmyelinated neurons in adult rat dorsal ganglia (DRG) express one or more of the co-receptors targeted by glial cell line-derived neurotrophic factor (GDNF), neurturin and artemin (GFRα1, GFRα2 and GFRα3 respectively). The function of these GDNF family ligands (GFLs) is not fully elucidated but recent evidence suggests GFLs could function in sensory neuron regeneration after nerve injury and peripheral nociceptor sensitisation. In this study, we used immunohistochemistry to determine if the DRG neurons targeted by each GFL change after sciatic nerve injury. We compared complete sciatic nerve transection and the chronic constriction model and found the pattern of changes incurred by each injury was broadly similar. In lumbar spinal cord, there was a widespread increase in neuronal GFRα1 immunoreactivity (IR) in the L1-6 dorsal horn. GFRα3-IR also increased but in a more restricted area. In contrast, GFRα2-IR decreased in patches of superficial dorsal horn and this loss was more extensive after transection injury. No change in calcitonin gene-related peptide-IR was detected after either injury. Analysis of double-immunolabelled L5 DRG sections suggested the main effect of injury on GFRα1- and GFRα3-IR was to increase expression in both myelinated and unmyelinated neurons. In contrast, no change in basal expression of GFRα2-IR was detected in DRG by analysis of fluorescence intensity and there was a small but significant reduction in GFRα2-IR neurons. Our results suggest the DRG neuronal populations targeted by GDNF, neurturin or artemin, and the effect of exogenous GFLs could change significantly after a peripheral nerve injury. PMID:20533358

  2. Differences in cutaneous sensory response properties of single somatosensory cortical neurons in awake and halothane anesthetized rats.

    PubMed

    Chapin, J K; Waterhouse, B D; Woodward, D J

    1981-01-01

    The major aim of this study was to investigate the effect of halothane anesthesia on different latency components of cutaneous sensory responses of single units in the primary somatosensory (SI) cortex of rats. Quantitative studies of computer generated post-stimulus time histograms were used to determine whether the increase in "nonspecific" properties often observed in the SI cortices of awake animals were attributable to a generally increased sensory responsiveness of these cells or to a selective increase of certain "nonspecific" components of their sensory response. Sensory "specificity" was investigated here by measuring the size of cutaneous receptive fields of single cells and testing their ability to follow high stimulus frequencies. Histograms generated by repetitive touch stimulation of the forepaw in awake animals were divisible into the following different latency components: (1) a short latency excitatory response which was often divisible into two peaks (E1a and E1b), and occasionally (2) a post-excitatory inhibitory phase (I1) and/or (3) a long latency excitatory peak (E2). In anesthetized animals spontaneous discharge rates were lower and the proportion of cells exhibiting either pure inhibition or post-excitatory inhibition was increased. By contrast, the longer latency excitatory components (E1b and E2) were weaker and were seen much less frequently than in the awake situation. In nine cells tested in the awake state and then again in the anesthetized state the magnitude, receptive field size, and ability to follow high frequencies of the E1a peak was slightly reduced. The E1b and E2 peaks seen in the awake state, on the other hand, were completely abolished by anesthesia. In awake animals the E1b and E2 phases exhibited relatively "nonspecific" physiological properties. This was indicated by the facts that: (1) the cutaneous receptive fields of the E1a peak were slightly smaller than those of the E1b peaks and much smaller than those of the E2

  3. Influence of human skin injury on regeneration of sensory neurons.

    PubMed

    Taherzadeh, O; Otto, W R; Anand, U; Nanchahal, J; Anand, P

    2003-06-01

    The regeneration of sensory nerve fibres is regulated by trophic factors released from their target tissue, particularly the basal epidermis, and matrix molecules. Means to modulate this response may be useful for the treatment of neuromas and painful hypertrophic scars and of sensory deficits in skin grafts and flaps. We have developed an in vitro model of sensory neuron regeneration on human skin in order to study the mechanisms of sensory dysfunction in pathological conditions. Adult rat sensory neurons were co-cultured with unfixed cryosections of normal or injured (crushed) human skin for 72 h. Neurons were immunostained for growth-associated protein-43 and the neurite lengths of neuronal cell bodies situated in various skin regions were measured. Two-way analysis of variance was performed. Neurites of sensory cell bodies on epidermis of normal skin were the shortest, with a mean +/- SEM of 75+/-10 micrometer, whereas those of cells on the dermo-epidermal junction were the longest, with a mean +/- SEM of 231+/-18 micrometer. Neurons on the dermo-epidermal junction of injured skin had significantly longer neurites than those on the same region of normal skin (mean +/- SEM = 289+/-21 micrometer). Regeneration of sensory neurons may be influenced by extracellular matrix molecules, matrix-binding growth factors and trophic factors. Altered substrate or trophic factors in injured skin may explain the increase of neurite lengths. This in vitro model may be useful for studying the molecular mechanisms of sensory recovery and the development of neuropathic pain following peripheral nerve injury.

  4. Patch-clamping Drosophila sensory neurons.

    PubMed

    Kucher, Volodymyr; Eaton, Benjamin A; Stockand, James D; Boiko, Nina

    2013-01-01

    Electrophysiological studies provide essential clues about the regulation and physiological function of ion channel proteins. Probing ion channel activity in vivo, though, often is challenging. This can limit the usefulness of such model organisms as Drosophila for electrophysiological studies. This is unfortunate because these genetically tractable organisms represent powerful research tools that facilitate elaboration of complex questions of physiology. Here, we describe a recently developed method for recording ion channel activity in Drosophila sensory neurons. This approach is based on patch-clamping primary neuron cultures from Drosophila embryos. Such cultures allow the study of ion channels in different genetic backgrounds. In addition to describing how to prepare a primary neuronal cell culture from Drosophila embryos, we discuss, as an example of utility, analysis of Na(+) currents in cultured class IV multidendritic (md) sensory neurons with the patch clamp technique. Excitability of md sensory neurons, manifested as action potential firing, is revealed with whole-cell current-clamping. Voltage-clamping class IV md neurons revealed the activity of the voltage-gated Na(+) channel, paralytic. Moreover, challenging class IV md neurons with acidic pH activates acid-sensing inward Na(+) currents. Genetic manipulation of Drosophila combined with this electrophysiological readout of activity identifies pickpocket1 (Ppk1), a member of the Deg/ENaC channel family, as responsible for conducting an acid-sensing Na(+) current in class IV md sensory neurons.

  5. Amino acid odorants stimulate microvillar sensory neurons.

    PubMed

    Lipschitz, David L; Michel, William C

    2002-03-01

    The olfactory epithelium (OE) of zebrafish is populated with ciliated and microvillar olfactory sensory neurons (OSNs). Whether distinct classes of odorants specifically activate either of these unique populations of OSNs is unknown. Previously we demonstrated that zebrafish OSNs could be labeled in an activity-dependent fashion by amino acid but not bile acid odorants. To determine which sensory neuron type was stimulated by amino acid odorants, we labeled OSNs using the ion channel permeant probe agmatine (AGB) and analyzed its distribution with conventional light- and electron-microscope immunocytochemical techniques. Approximately 7% of the sensory epithelium was labeled by AGB exposure alone. Following stimulation with one of the eight amino acids tested, the proportion of labeled epithelium increased from 9% for histidine to 19% for alanine; amino acid stimulated increases in labeling of 2-12% over control labeling. Only histidine failed to stimulate a significant increase in the proportion of labeled OSNs compared to control preparations. Most amino acid sensitive OSNs were located superficially in the epithelium and immuno-electron microscopy demonstrated that the labeled OSNs were predominantly microvillar. Large numbers of nanogold particles (20-60 per 1.5 microm(2)) were associated with microvillar olfactory sensory neurons (MSNs), while few such particles (<15 per 1.5 microm(2)) were observed over ciliated olfactory sensory neurons (CSNs), supporting cells (SCs) and areas without tissue, such as the lumen above the OE. Collectively, these findings indicate that microvillar sensory neurons are capable of detecting amino acid odorants.

  6. An ionic current model for neurons in the rat medial nucleus tractus solitarii receiving sensory afferent input.

    PubMed Central

    Schild, J H; Khushalani, S; Clark, J W; Andresen, M C; Kunze, D L; Yang, M

    1993-01-01

    1. Neurons from a horizontal slice of adult rat brainstem were examined using intracellular recording techniques. Investigations were restricted to a region within the nucleus tractus solitarii, medial to the solitary tract and centred on the obex (mNTS). Previous work has shown this restricted area of the NTS to contain the greatest concentration of aortic afferent baroreceptor terminal fields. Electrical stimulation of the tract elicited short-latency excitatory postsynaptic potentials in all neurons. 2. mNTS neurons were spontaneously active with firing frequencies ranging between 1 and 10 Hz, at resting potentials of -65 to -45 mV. These neurons did not exhibit spontaneous bursting activity. 3. Depolarizing current injection immediately evoked a finite, high-frequency spike discharge which rapidly declined to a lower steady-state level (i.e. spike frequency adaptation, SFA). Increasing depolarizations produced a marked increase in the peak instantaneous frequency but a much smaller increase in the steady-state firing level. 4. Conditioning with a hyperpolarizing prepulse resulted in a prolonged delay of up to 600 ms before the first action potential (i.e. delayed excitation, DE) with an attendant decrease in peak discharge rates. DE was modulated by both the magnitude and duration of the prestimulus hyperpolarization, as well as the magnitude of the depolarizing stimulus. Tetrodotoxin (TTX) eliminated spike discharge but had little effect on the ramp-like membrane depolarization characteristic of DE. 5. We have developed a mathematical model for mNTS neurons to facilitate our understanding of the interplay between the underlying ionic currents. It consists of a comprehensive membrane model of the Hodgkin-Huxley type coupled with a fluid compartment model describing cytoplasmic [Ca2+]i homeostasis. 6. The model suggests that (a) SFA is caused by an increase in [Ca2+]i which activates the outward K+ current, IK,Ca, and (b) DE results from the competitive

  7. Hypoxic increase in nitric oxide generation of rat sensory neurons requires activation of mitochondrial complex II and voltage-gated calcium channels.

    PubMed

    Henrich, M; Paddenberg, R; Haberberger, R V; Scholz, A; Gruss, M; Hempelmann, G; Kummer, W

    2004-01-01

    Recently, we have demonstrated that sensory neurons of rat lumbar dorsal root ganglia (DRG) respond to hypoxia with an activation of endothelial nitric oxide (NO) synthase (eNOS) resulting in enhanced NO production associated with mitochondria which contributes to resistance against hypoxia. Extracellular calcium is essential to this effect. In the present study on rat DRG slices, we set out to determine what types of calcium channels operate under hypoxia, and which upstream events contribute to their activation, thereby focusing upon mitochondrial complex II. Both the metallic ions Cd2+ and Ni2+, known to inhibit voltage-gated calcium channels and T-type channels, respectively, and verapamil and nifedipine, typical blocker of L-type calcium channels completely prevented the hypoxic neuronal NO generation. Inhibition of complex II by thenoyltrifluoroacetone at the ubiquinon binding site or by 3-nitropropionic acid at the substrate binding site largely diminished hypoxic-induced NO production while having an opposite effect under normoxia. An additional blockade of voltage-gated calcium channels entirely abolished the hypoxic response. The complex II inhibitor malonate inhibited both normoxic and hypoxic NO generation. These data show that complex II activity is required for increased hypoxic NO production. Since succinate dehydrogenase activity of complex II decreased at hypoxia, as measured by histochemistry and densitometry, we propose a hypoxia-induced functional switch of complex II from succinate dehydrogenase to fumarate reductase, which subsequently leads to activation of voltage-gated calcium channels resulting in increased NO production by eNOS.

  8. Thermal stimulation of primary sensory neurons in the rat hind paw: effect of morphine on ERK1/2 phosphorylation, TRPV1 and TRPA1 channel expression.

    PubMed

    Donnerer, Josef; Liebmann, Ingrid

    2012-01-01

    Temperature-sensitive transient receptor potential (TRP) channels or 'thermo-TRP' were stimulated on rat sensory afferents, and the effects on the phosphorylation of ERK1/2, on the regulation of TRPV1 and TRPA1, as well as the pharmacological modulation by the opioid analgesic morphine were investigated. The thermal stimuli were applied to the rat hind paw by immersion into either hot or cold water. Phospho-ERK1/2 (p-ERK1/2) was measured by fluorescence-immunohistochemistry in the lumbar dorsal root ganglion (DRG) neurons. TRP channel mRNA expression was measured by RT-PCR in the innervating DRGs, and the protein content of TRPV1 and TRPA1 was determined by Western blot in the DRGs and in the sciatic nerve. The thermal stimuli led to a time-dependent increase in the number of DRG cells displaying cytoplasmic and nuclear staining for p-ERK1/2. Morphine partly prevented this increase in ERK1/2 phosphorylation, exerting its effect mainly on the nuclear staining. The mRNA expression for TRPV1 and TRPA1 in the DRG did not change within 24 h following the thermal stimuli. However, the protein content of both TRPV1 and TRPA1 was regulated by the thermal stimulation and by morphine. In the DRGs and in the sciatic nerve, heat or cold stimuli per se tended to decrease TRP protein levels, whereas with morphine pretreatment protein levels were raised. The present findings shed new light on the time-dependent reactions of primary sensory neurons towards irritant thermal stimuli to the skin and on their opioid modulation.

  9. Molecular mechanism for opioid dichotomy: bidirectional effect of μ-opioid receptors on P2X₃ receptor currents in rat sensory neurones.

    PubMed

    Chizhmakov, Igor; Kulyk, Vyacheslav; Khasabova, Iryna; Khasabov, Sergey; Simone, Donald; Bakalkin, Georgy; Gordienko, Dmitri; Verkhratsky, Alexei; Krishtal, Oleg

    2015-06-01

    Here, we describe a molecular switch associated with opioid receptors-linked signalling cascades that provides a dual opioid control over P2X3 purinoceptor in sensory neurones. Leu-enkephalin inhibited P2X3-mediated currents with IC50 ~10 nM in ~25% of small nociceptive rat dorsal root ganglion (DRG) neurones. In contrast, in neurones pretreated with pertussis toxin leu-enkephalin produced stable and significant increase of P2X3 currents. All effects of opioid were abolished by selective μ-opioid receptor antagonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP), nonselective inhibitor naloxone, and by PLC inhibitor U73122. Thus, we discovered a dual link between purinoceptors and μ-opioid receptors: the latter exert both inhibitory (pertussis toxin-sensitive) and stimulatory (pertussis toxin-insensitive) actions on P2X3 receptors through phospholipase C (PLC)-dependent pathways. This dual opioid control of P2X3 receptors may provide a molecular explanation for dichotomy of opioid therapy. Pharmacological control of this newly identified facilitation/inhibition switch may open new perspectives for the adequate medical use of opioids, the most powerful pain-killing agents known today.

  10. Mitochondria and plasma membrane Ca2+-ATPase control presynaptic Ca2+ clearance in capsaicin-sensitive rat sensory neurons

    PubMed Central

    Shutov, Leonid P; Kim, Man-Su; Houlihan, Patrick R; Medvedeva, Yuliya V; Usachev, Yuriy M

    2013-01-01

    The central processes of primary nociceptors form synaptic connections with the second-order nociceptive neurons located in the dorsal horn of the spinal cord. These synapses gate the flow of nociceptive information from the periphery to the CNS, and plasticity at these synapses contributes to centrally mediated hyperalgesia and allodynia. Although exocytosis and synaptic plasticity are controlled by Ca2+ at the release sites, the mechanisms underlying presynaptic Ca2+ signalling at the nociceptive synapses are not well characterized. We examined the presynaptic mechanisms regulating Ca2+ clearance following electrical stimulation in capsaicin-sensitive nociceptors using a dorsal root ganglion (DRG)/spinal cord neuron co-culture system. Cytosolic Ca2+ concentration ([Ca2+]i) recovery following electrical stimulation was well approximated by a monoexponential function with a τ∼2 s. Inhibition of sarco-endoplasmic reticulum Ca2+-ATPase did not affect presynaptic [Ca2+]i recovery, and blocking plasmalemmal Na+/Ca2+ exchange produced only a small reduction in the rate of [Ca2+]i recovery (∼12%) that was independent of intracellular K+. However, [Ca2+]i recovery in presynaptic boutons strongly depended on the plasma membrane Ca2+-ATPase (PMCA) and mitochondria that accounted for ∼47 and 40%, respectively, of presynaptic Ca2+ clearance. Measurements using a mitochondria-targeted Ca2+ indicator, mtPericam, demonstrated that presynaptic mitochondria accumulated Ca2+ in response to electrical stimulation. Quantitative analysis revealed that the mitochondrial Ca2+ uptake is highly sensitive to presynaptic [Ca2+]i elevations, and occurs at [Ca2+]i levels as low as ∼200–300 nm. Using RT-PCR, we detected expression of several putative mitochondrial Ca2+ transporters in DRG, such as MCU, Letm1 and NCLX. Collectively, this work identifies PMCA and mitochondria as the major regulators of presynaptic Ca2+ signalling at the first sensory synapse, and underlines the high

  11. Spectral mixing of rhythmic neuronal signals in sensory cortex

    PubMed Central

    Ahrens, Kurt F.; Levine, Herbert; Suhl, Harry; Kleinfeld, David

    2002-01-01

    The ability to compute the difference between two frequencies depends on a nonlinear operation that mixes two periodic signals. Behavioral and psychophysical evidence suggest that such mixing is likely to occur in the mammalian nervous system as a means to compare two rhythmic sensory signals, such as occurs in human audition, and as a means to lock an intrinsic rhythm to a sensory input. However, a neurological substrate for mixing has not been identified. Here we address the issue of nonlinear mixing of neuronal activity in the vibrissa primary sensory cortex of rat, a region that receives intrinsic as well as sensory-driven rhythmic input during natural whisking. In our preparation, the intrinsic signal originates from cortical oscillations that were induced by anesthetics, and the extrinsic input is introduced by periodic stimulation of vibrissae. We observed that the local extracellular current in vibrissa primary sensory cortex contained oscillatory components at the sum and difference of the intrinsic and extrinsic frequencies. In complementary experiments, we observed that the simultaneous stimulation of contralateral and ipsilateral vibrissae at different frequencies also led to current flow at the sum and difference frequencies. We show theoretically that the relative amplitudes of the observed mixture terms can be accounted for by a threshold nonlinearity in the input–output relation of the underlying neurons. In general, our results provide a neurological substrate for the modulation and demodulation of rhythmic neuronal signals for sensory coding and feedback stabilization of motor output. PMID:12403828

  12. H2S-induced HCO3- secretion in the rat stomach--involvement of nitric oxide, prostaglandins, and capsaicin-sensitive sensory neurons.

    PubMed

    Takeuchi, Koji; Ise, Fumitaka; Takahashi, Kento; Aihara, Eitaro; Hayashi, Shusaku

    2015-04-30

    Hydrogen sulfide (H2S) is known to be an important gaseous mediator that affects various functions under physiological and pathological conditions. We examined the effects of NaHS, a H2S donor, on HCO3(-) secretion in rat stomachs and investigated the mechanism involved in this response. Under urethane anesthesia, rat stomachs were mounted on an ex vivo chamber and perfused with saline. Acid secretion had been inhibited by omeprazole. The secretion of HCO3(-) was measured at pH 7.0 using a pH-stat method and by the addition of 10 mM HCl. NaHS (0.5-10 mM) was perfused in the stomach for 5 min. Indomethacin or L-NAME was administered s.c. before NaHS treatment, while glibenclamide (a KATP channel blocker), ONO-8711 (an EP1 antagonist), or propargylglycine (a cystathionine γ-lyase inhibitor) was given i.p. before. The mucosal perfusion of NaHS dose-dependently increased the secretion of HCO3(-), and this effect was significantly attenuated by indomethacin, L-NAME, and sensory deafferentation, but not by glibenclamide or ONO-8711. The luminal output of nitric oxide, but not the mucosal production of prostaglandin E2, was increased by the perfusion of NaHS. Mucosal acidification stimulated HCO3(-) secretion, and this response was inhibited by sensory deafferentation, indomethacin, L-NAME, and ONO-8711, but not by propargylglycine. These results suggested that H2S increased HCO3(-) secretion in the stomach, and this effect was mediated by capsaicin-sensitive afferent neurons and dependent on nitric oxide and prostaglandins, but not ATP-sensitive K(+) channels. Further study is needed to define the role of endogenous H2S in the mechanism underlying acid-induced gastric HCO3(-) secretion. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Effects of unilateral and bilateral training in a reaching task on dendritic branching of neurons in the rat motor-sensory forelimb cortex.

    PubMed

    Greenough, W T; Larson, J R; Withers, G S

    1985-09-01

    Effects of motor training on a neocortical nerve cell population involved in performance of the motor task were assessed by measuring Layer V pyramidal neuron apical dendritic branching in motor-sensory forelimb cortex of rats trained to reach into a tube for food. Rats were trained to reach with the forepaw they preferred to use (group PRAC), the nonpreferred forepaw (REV), both forepaws (ALT), or neither forepaw (CONT). Across groups, hemispheres opposite trained forepaws had larger apical dendritic fields, in terms of total dendritic length, number of oblique branches from the apical shaft, and length of terminal branches. Similar, although somewhat less consistent, effects were seen when results were analyzed for between- (CONT vs ALT) and within-subject comparisons (trained vs nontrained hemispheres of REV and PRAC). This finding is compatible with the hypothesis that altered dendritic patterns, with associated synapses, are involved in storage of information from the training experience. The within-subject effects mitigate suggestions that these differences arise from generally acting hormonal or metabolic consequences of the training experience, although the possibility that these effects result from neural activity per se and are unrelated to information storage cannot be excluded.

  14. Study of orexins signal transduction pathways in rat olfactory mucosa and in olfactory sensory neurons-derived cell line Odora: multiple orexin signalling pathways.

    PubMed

    Gorojankina, Tatiana; Grébert, Denise; Salesse, Roland; Tanfin, Zahra; Caillol, Monique

    2007-06-07

    Orexins A and B (OxA and OxB) are multifunctional neuropeptides implicated in the regulation of energy metabolism, wakefulness but also in a broad range of motivated behaviours. They signal through two G-protein-coupled receptors: orexin receptor 1 and 2 (Ox1R and Ox2R). The orexins and their receptors are present at all levels of the rat olfactory system: epithelium, bulb, piriform cortex but their signalling mechanisms remain unknown. We have studied orexins signal transduction pathways in the rat olfactory mucosa (OM) and in the Odora cell line derived from olfactory sensory neurons and heterologously expressing Ox1R or Ox2R. We have demonstrated by western blot and RT-PCR that multiple components of adenylyl cyclase (AC) and phospholipase C (PLC) signalling pathways were identical in OM and Odora cells. OxA and OxB induced a weak increase in IP3 in OM; they induced a significant rise in cAMP and IP3 in Odora transfected cells, suggesting the activation of AC and PLC pathways. Both OxA and OxB induced intracellular calcium elevation and transient activation of MAP kinases (ERK42/44) in Odora/Ox1R and Odora/Ox2R cells. These results suggest the existence of multiple orexins signalling pathways in Odora cells and probably in OM, corresponding to different possible roles of these peptides.

  15. TTA-P2 Is a Potent and Selective Blocker of T-Type Calcium Channels in Rat Sensory Neurons and a Novel Antinociceptive Agent

    PubMed Central

    Choe, WonJoo; Messinger, Richard B.; Leach, Emily; Eckle, Veit-Simon; Obradovic, Aleksandar; Salajegheh, Reza; Jevtovic-Todorovic, Vesna

    2011-01-01

    Several agents that are preferential T-type calcium (T-channel) blockers have shown promise as being effective in alleviating acute and chronic pain, suggesting an urgent need to identify even more selective and potent T-channel antagonists. We used small, acutely dissociated dorsal root ganglion (DRG) cells of adult rats to study the in vitro effects of 3,5-dichloro-N-[1-(2,2-dimethyl-tetrahydro-pyran-4-ylmethyl)-4-fluoro-piperidin-4-ylmethyl]-benzamide (TTA-P2), a derivative of 4-aminomethyl-4-fluoropiperdine, on T currents, as well as other currents known to modulate pain transmission. We found that TTA-P2 potently and reversibly blocked DRG T currents with an IC50 of 100 nM and stabilized channel in the inactive state, whereas high-voltage-activated calcium and sodium currents were 100- to 1000-fold less sensitive to channel blocking effects. In in vivo studies, we found that intraperitoneal injections of 5 or 7.5 mg/kg TTA-P2 reduced pain responses in mice in phases 1 and 2 of the formalin test. Furthermore, TTA-P2, at 10 mg/kg i.p., selectively and completely reversed thermal hyperalgesia in diabetic rats treated with streptozocin but had no effect on the nociceptive response of healthy animals. The antihyperalgesic effects of TTA-P2 in diabetic rats were completely abolished by administration of oligonucleotide antisense for CaV3.2 isoform of T channels. Thus, TTA-P2 is not only the most potent and selective blocker of T channels in sensory neurons yet described, but it also demonstrates the potential for the pharmacological effectiveness of this approach in addressing altered nociceptive responses in animal models of both inflammatory and neuropathic pain. PMID:21821734

  16. Prostaglandin E2 potentiates a TTX-resistant sodium current in rat capsaicin-sensitive vagal pulmonary sensory neurones.

    PubMed

    Kwong, Kevin; Lee, Lu-Yuan

    2005-04-15

    Capsaicin-sensitive vagal pulmonary neurones (pulmonary C neurones) play an important role in regulating airway function. During airway inflammation, the level of prostaglandin E(2) (PGE(2)) increases in the lungs and airways. PGE(2) has been shown to sensitize isolated pulmonary C neurones. The somatosensory correlate of the pulmonary C neurone, the small-diameter nociceptive neurone of the dorsal root ganglion, contains a high percentage of tetrodotoxin-resistant sodium currents (TTX-R I(Na)). Therefore, this study was carried out to determine whether these channel currents are involved in the PGE(2)-induced sensitization of pulmonary C neurones. We used the perforated patch-clamp technique to study the effects of PGE(2) on the TTX-R I(Na) in acutely cultured capsaicin-sensitive pulmonary neurones that were identified by retrograde labelling with a fluorescent tracer, DiI. We found that the pulmonary neurones sensitive to capsaicin had a higher percentage of TTX-R I(Na) than that of capsaicin-insensitive pulmonary neurones. PGE(2) exposure increased the evoked TTX-R I(Na) when experiments were performed at both room temperature and at 37 degrees C. Furthermore, stimulation of the adenylyl cyclase/protein kinase A pathway with either forskolin or Sp-5,6-DCl-cBiMPS potentiated the TTX-R I(Na) in a manner similar to that of PGE(2). We conclude that these modulatory effects of PGE(2) on TTX-R I(Na) play an important role in the sensitization of pulmonary C neurones.

  17. Sensory neuron subpopulation-specific dysregulation of intracellular calcium in a rat model of chemotherapy-induced peripheral neuropathy

    PubMed Central

    Yilmaz, E; Gold, MS

    2015-01-01

    The purpose of the present study was to test the prediction that the unique manifestation of chemotherapeutic-induced peripheral neuropathy (CIPN) would be reflected in a specific pattern of changes in the regulation of the intracellular Ca2+ concentration ([Ca2+]i) in subpopulations of cutaneous neurons. To test this prediction, we characterized the pattern of changes in mechanical nociceptive threshold associated with paclitaxel administration (2 mg/kg, iv, every other day for four days), as well as the impact of target of innervation and paclitaxel treatment on the regulation of [Ca2+]i in subpopulations of putative nociceptive and non-nociceptive neurons. Neurons innervating the glabrous and hairy skin of the hindpaw as well as the thigh were identified with retrograde tracers, and fura-2 was used to assess changes in [Ca2+]i. Paclitaxel was associated with a persistent decrease in mechanical nociceptive threshold in response to stimuli applied to the glabrous skin of the hindpaw, but not the hairy skin of the hindpaw or the thigh. However, in both putative nociceptive and non-nociceptive neurons, resting [Ca2+]i was significantly lower in neurons innervating the thigh after treatment. The magnitude of the depolarization-evoked Ca2+ transient was also lower in putative non-nociceptive thigh neurons. More interestingly, while paclitaxel had no detectable influence on either resting or depolarization-evoked Ca2+ transients in putative non-nociceptive neurons, in putative nociceptive neurons there was a subpopulation- specific decrease in the duration of the evoked Ca2+ transient that was largely restricted to neurons innervating the glabrous skin. These results suggest that peripheral nerve length alone, does not account for the selective distribution of CIPN symptoms. Rather, they suggest the symptoms of CIPN reflect an interaction between the toxic actions of the therapeutic and unique properties of the neurons deleteriously impacted. PMID:25982563

  18. Sensory neuron subpopulation-specific dysregulation of intracellular calcium in a rat model of chemotherapy-induced peripheral neuropathy.

    PubMed

    Yilmaz, E; Gold, M S

    2015-08-06

    The purpose of the present study was to test the prediction that the unique manifestation of chemotherapeutic-induced peripheral neuropathy (CIPN) would be reflected in a specific pattern of changes in the regulation of the intracellular Ca(2+) concentration ([Ca(2+)]i) in subpopulations of cutaneous neurons. To test this prediction, we characterized the pattern of changes in mechanical nociceptive threshold associated with paclitaxel administration (2mg/kg, iv, every other day for four days), as well as the impact of target of innervation and paclitaxel treatment on the regulation of [Ca(2+)]i in subpopulations of putative nociceptive and non-nociceptive neurons. Neurons innervating the glabrous and hairy skin of the hindpaw as well as the thigh were identified with retrograde tracers, and fura-2 was used to assess changes in [Ca(2+)]i. Paclitaxel was associated with a persistent decrease in mechanical nociceptive threshold in response to stimuli applied to the glabrous skin of the hindpaw, but not the hairy skin of the hindpaw or the thigh. However, in both putative nociceptive and non-nociceptive neurons, resting [Ca(2+)]i was significantly lower in neurons innervating the thigh after treatment. The magnitude of the depolarization-evoked Ca(2+) transient was also lower in putative non-nociceptive thigh neurons. More interestingly, while paclitaxel had no detectable influence on either resting or depolarization-evoked Ca(2+) transients in putative non-nociceptive neurons, in putative nociceptive neurons there was a subpopulation-specific decrease in the duration of the evoked Ca(2+) transient that was largely restricted to neurons innervating the glabrous skin. These results suggest that peripheral nerve length alone, does not account for the selective distribution of CIPN symptoms. Rather, they suggest the symptoms of CIPN reflect an interaction between the toxic actions of the therapeutic and unique properties of the neurons deleteriously impacted.

  19. Role of capsaicin-sensitive peripheral sensory neurons in anorexic responses to intravenous infusions of cholecystokinin, peptide YY-(3-36), and glucagon-like peptide-1 in rats.

    PubMed

    Reidelberger, Roger; Haver, Alvin; Anders, Krista; Apenteng, Bettye

    2014-10-15

    Cholecystokinin (CCK)-induced suppression of feeding is mediated by vagal sensory neurons that are destroyed by the neurotoxin capsaicin (CAP). Here we determined whether CAP-sensitive neurons mediate anorexic responses to intravenous infusions of gut hormones peptide YY-(3-36) [PYY-(3-36)] and glucagon-like peptide-1 (GLP-1). Rats received three intraperitoneal injections of CAP or vehicle (VEH) in 24 h. After recovery, non-food-deprived rats received at dark onset a 3-h intravenous infusion of CCK-8 (5, 17 pmol·kg⁻¹·min⁻¹), PYY-(3-36) (5, 17, 50 pmol·kg⁻¹·min⁻¹), or GLP-1 (17, 50 pmol·kg⁻¹·min⁻¹). CCK-8 was much less effective in reducing food intake in CAP vs. VEH rats. CCK-8 at 5 and 17 pmol·kg⁻¹·min⁻¹ reduced food intake during the 3-h infusion period by 39 and 71% in VEH rats and 7 and 18% in CAP rats. In contrast, PYY-(3-36) and GLP-1 were similarly effective in reducing food intake in VEH and CAP rats. PYY-(3-36) at 5, 17, and 50 pmol·kg⁻¹·min⁻¹ reduced food intake during the 3-h infusion period by 15, 33, and 70% in VEH rats and 13, 30, and 33% in CAP rats. GLP-1 at 17 and 50 pmol·kg⁻¹·min⁻¹ reduced food intake during the 3-h infusion period by 48 and 60% in VEH rats and 30 and 52% in CAP rats. These results suggest that anorexic responses to PYY-(3-36) and GLP-1 are not primarily mediated by the CAP-sensitive peripheral sensory neurons (presumably vagal) that mediate CCK-8-induced anorexia.

  20. Functional recovery of neuronal activity in rat whisker-barrel cortex sensory pathway from freezing injury after transplantation of adult bone marrow stromal cells.

    PubMed

    Mori, Kentaro; Iwata, Junko; Miyazaki, Masahiro; Nakao, Yasuaki; Maeda, Minoru

    2005-07-01

    The effect of transplantation of adult bone marrow stromal cells (MSCs) into the freeze-lesioned left barrel field cortex in the rat was investigated by measurement of local cerebral glucose utilization (lCMR(glc)) in the anatomic structures of the whisker-to-barrel cortex sensory pathway. Bone marrow stromal cells or phosphate-buffered saline (PBS) were injected intracerebrally into the boundary zone 1 h after induction of the freezing cortical lesion. Three weeks after surgery, the 2-[(14)C]deoxyglucose method was used to measure lCMR(glc) during right whisker stimulation. The volume of the primary necrotic freezing lesion was significantly reduced (P<0.05), and secondary retrograde degeneration in the left ventral posteromedial (VPM) thalamic nucleus was diminished in the MSC-treated group. Local cerebral glucose utilization measurements showed that the freezing cortical lesion did not alter the metabolic responses to stimulation in the brain stem trigeminal nuclei, but eliminated the responses in the left VPM nucleus and periphery of the barrel cortex in the PBS-treated group. The left/right (stimulated/unstimulated) lCMR(glc) ratios were significantly improved in both the VPM nucleus and periphery of the barrel cortex in the MSC-treated group compared with the PBS-treated group (P<0.05). These results indicate that MSC transplantation in adults may stimulate metabolic and functional recovery in injured neuronal pathways.

  1. Copulation or sensory cues from the female augment Fos expression in arginine vasopressin neurons of the posterodorsal medial amygdala of male rats

    PubMed Central

    2014-01-01

    Background The posterodorsal part of the medial amygdala is essential for processing reproductively salient sensory information in rodents. This is the initial brain structure where information from olfactory system and male hormones intersect. The neurochemical identity of the neurons participating in the sensory processing in medial amygdala remains presently undetermined. Many neurons in this brain structure express arginine vasopressin in a testosterone-dependent manner, suggesting that this neuropeptide is maintained by the androgenic milieu. Method Here we use Fos, a protein expressed by recently active neurons, to quantify activation of arginine vasopressin neurons after exposure to odor from physically inaccessible female. We compare it to mating with accessible female and to reproductively innocuous odor. Results We show that inaccessible female activate arginine vasopressin neurons in the male posterodorsal medial amygdala. The magnitude of activation is not further enhanced when physical access with resultant mating is granted, even though it remains undetermined if same population of AVP neurons is activated by both inaccessible female and copulation. We also show that arginine vasopressin activation cannot be fully accounted for by mere increase in the number of Fos and AVP neurons. Conclusion These observations posit a role for the medial amygdala arginine vasopressin in reproductive behaviors, suggesting that these neurons serve as integrative node between the hormonal status of the animal and the availability of reproductive opportunities. PMID:24926317

  2. Electroacupuncture attenuates visceral hyperalgesia and inhibits the enhanced excitability of colon specific sensory neurons in a rat model of irritable bowel syndrome.

    PubMed

    Xu, G-Y; Winston, J H; Chen, J D Z

    2009-12-01

    The causes of irritable bowel syndrome remain elusive and there are few effective treatments for pain in this syndrome. Electroacupunture (EA) is used extensively for treatment of various painful conditions including chronic visceral hyperalgesia (CVH). However, mechanism of its analgesic effect remains unknown. This study was designed to investigate effect of EA on colon specific dorsal root ganglion (DRG) neurons in rats with CVH. CVH was induced by intracolonic injection of acetic acid (AA) in 10-day-old rats. Electromyography and patch clamp recordings were performed at age of 8-10 weeks. Colon DRG neurons were labelled by injection of DiI into the colon wall. EA was given at ST36 in both hindlimbs. As adults, neonatal AA-injected rats displayed an increased sensitivity to colorectal distension (CRD) and an enhanced excitability of colon DRG neurons. EA treatment for 40 min significantly attenuated the nociceptive responses to CRD in these rats; this attenuation was reversed by pretreatment with naloxone. EA treatment for 40 min per day for 5 days produced a prolonged analgesic effect and normalized the enhanced excitability of colon DRG neurons. Furthermore, in vitro application of [D-Ala(2), N-MePhe(4), Gly(5)-Ol] enkephalin (DAMGO) suppressed the enhanced excitability of colon neurons from rats with CVH. These findings suggest that EA produced-visceral analgesia, which might be mediated in a large part by endogenous opioids pathways, is associated with reversal of the enhanced excitability of colon DRG neurons in rats with CVH.

  3. Culturing rat hippocampal neurons.

    PubMed

    Audesirk, G; Audesirk, T; Ferguson, C

    2001-01-01

    Cultured neurons are widely used to investigate the mechanisms of neurotoxicity. Embryonic rat hippocampal neurons may be grown as described under a wide variety of conditions to suit differing experimental procedures, including electrophysiology, morphological analysis of neurite development, and various biochemical and molecular analyses.

  4. Cervical vagus nerve stimulation augments spontaneous discharge in second- and higher-order sensory neurons in the rat nucleus of the solitary tract.

    PubMed

    Beaumont, Eric; Campbell, Regenia P; Andresen, Michael C; Scofield, Stephanie; Singh, Krishna; Libbus, Imad; KenKnight, Bruce H; Snyder, Logan; Cantrell, Nathan

    2017-08-01

    Vagus nerve stimulation (VNS) currently treats patients with drug-resistant epilepsy, depression, and heart failure. The mild intensities used in chronic VNS suggest that primary visceral afferents and central nervous system activation are involved. Here, we measured the activity of neurons in the nucleus of the solitary tract (NTS) in anesthetized rats using clinically styled VNS. Our chief findings indicate that VNS at threshold bradycardic intensity activated NTS neuron discharge in one-third of NTS neurons. This VNS directly activated only myelinated vagal afferents projecting to second-order NTS neurons. Most VNS-induced activity in NTS, however, was unsynchronized to vagal stimuli. Thus, VNS activated unsynchronized activity in NTS neurons that were second order to vagal afferent C-fibers as well as higher-order NTS neurons only polysynaptically activated by the vagus. Overall, cardiovascular-sensitive and -insensitive NTS neurons were similarly activated by VNS: 3/4 neurons with monosynaptic vagal A-fiber afferents, 6/42 neurons with monosynaptic vagal C-fiber afferents, and 16/21 polysynaptic NTS neurons. Provocatively, vagal A-fibers indirectly activated C-fiber neurons during VNS. Elevated spontaneous spiking was quantitatively much higher than synchronized activity and extended well into the periods of nonstimulation. Surprisingly, many polysynaptic NTS neurons responded to half the bradycardic intensity used in clinical studies, indicating that a subset of myelinated vagal afferents is sufficient to evoke VNS indirect activation. Our study uncovered a myelinated vagal afferent drive that indirectly activates NTS neurons and thus central pathways beyond NTS and support reconsideration of brain contributions of vagal afferents underpinning of therapeutic impacts.NEW & NOTEWORTHY Acute vagus nerve stimulation elevated activity in neurons located in the medial nucleus of the solitary tract. Such stimuli directly activated only myelinated vagal afferents but

  5. Expression and properties of hyperpolarization-activated current in rat dorsal root ganglion neurons with known sensory function

    PubMed Central

    Gao, L L; McMullan, S; Djouhri, L; Acosta, C; Harper, A A; Lawson, S N

    2012-01-01

    The hyperpolarization-activated current (Ih) has been implicated in nociception/pain, but its expression levels in nociceptors remained unknown. We recorded Ih magnitude and properties by voltage clamp from dorsal root ganglion (DRG) neurons in vivo, after classifying them as nociceptive or low-threshold-mechanoreceptors (LTMs) and as having C-, Aδ- or Aα/β-conduction velocities (CVs). For both nociceptors and LTMs, Ih amplitude and Ih density (at −100 mV) were significantly positively correlated with CV. Median Ih magnitudes and Ih density in neuronal subgroups were respectively: muscle spindle afferents (MSAs): −4.6 nA, −33 pA pF−1; cutaneous Aα/β LTMs: −2.2 nA, −20 pA pF−1; Aβ-nociceptors: −2.6 nA, −21 pA pF−1; both Aδ-LTMs and nociceptors: −1.3 nA, ∼−14 pA pF−1; C-LTMs: −0.4 nA, −7.6 pA pF−1; and C-nociceptors: −0.26 nA, −5 pA pF−1. Ih activation slow time constants (slow τ values) were strongly correlated with fast τ values; both were shortest in MSAs. Most neurons had τ values consistent with HCN1-related Ih; others had τ values closer to HCN1+HCN2 channels, or HCN2 in the presence of cAMP. In contrast, median half-activation voltages (V0.5) of −80 to −86 mV for neuronal subgroups suggest contributions of HCN2 to Ih. τ values were unrelated to CV but were inversely correlated with Ih and Ih density for all non-MSA LTMs, and for Aδ-nociceptors. From activation curves ∼2–7% of Ih would be activated at normal membrane potentials. The high Ih may be important for excitability of A-nociceptors (responsible for sharp/pricking-type pain) and Aα/β-LTMs (tactile sensations and proprioception). Underlying HCN expression in these subgroups therefore needs to be determined. Altered Ih expression and/or properties (e.g. in chronic/pathological pain states) may influence both nociceptor and LTM excitability. PMID:22753545

  6. Chemogenetic silencing of neurons in retrosplenial cortex disrupts sensory preconditioning.

    PubMed

    Robinson, Siobhan; Todd, Travis P; Pasternak, Anna R; Luikart, Bryan W; Skelton, Patrick D; Urban, Daniel J; Bucci, David J

    2014-08-13

    An essential aspect of episodic memory is the formation of associations between neutral sensory cues in the environment. In light of recent evidence that this critical aspect of learning does not require the hippocampus, we tested the involvement of the retrosplenial cortex (RSC) in this process using a chemogenetic approach that allowed us to temporarily silence neurons along the entire rostrocaudal extent of the RSC. A viral vector containing the gene for a synthetic inhibitory G-protein-coupled receptor (hM4Di) was infused into RSC. When the receptor was later activated by systemic injection of clozapine-N-oxide, neural activity in RSC was transiently silenced (confirmed using a patch-clamp procedure). Rats expressing hM4Di and control rats were trained in a sensory preconditioning procedure in which a tone and light were paired on some trials and a white noise stimulus was presented alone on the other trials during the Preconditioning phase. Thus, rats were given the opportunity to form an association between a tone and a light in the absence of reinforcement. Later, the light was paired with food. During the test phase when the auditory cues were presented alone, controls exhibited more conditioned responding during presentation of the tone compared with the white noise reflecting the prior formation of a tone-light association. Silencing RSC neurons during the Preconditioning phase prevented the formation of an association between the tone and light and eliminated the sensory preconditioning effect. These findings indicate that RSC may contribute to episodic memory formation by linking essential sensory stimuli during learning. Copyright © 2014 the authors 0270-6474/14/3410982-07$15.00/0.

  7. Excitability parameters and sensitivity to anemone toxin ATX-II in rat small diameter primary sensory neurones discriminated by Griffonia simplicifolia isolectin IB4.

    PubMed

    Snape, Alistair; Pittaway, James F; Baker, Mark D

    2010-01-01

    Sensory neurone subtypes (< or = 25 microm apparent diameter) express a variety of Na(+) channels, where expression is linked to action potential duration, and associated with differential IB4-lectin binding. We hypothesized that sensitivity to ATX-II might also discriminate neurones and report that 1 microm has negligible or small effects on action potentials in IB4 +ve, but dramatically increased action potential duration in IB4 ve, neurones. The toxin did not act on tetrodotoxin-resistant (TTX-r) Na(V)1.8 currents; discrimination was based on tetrodotoxin-sensitive (TTX-s) Na(+) channel expression. We also explored the effects of varying the holding potential on current threshold, and the effect of repetitive activation on action currents in IB4 +ve and ve neurones. IB4 +ve neurones became more excitable with depolarization over the range 100 to 20 mV, but IB4 ve neurones exhibited peak excitability near 55 mV, and were inexcitable at 20 mV. Eliciting action potentials at 2 Hz, we found that peak inward action current in IB4 +ve neurones was reduced, whereas changes in the current amplitude were negligible in most IB4 ve neurones. Our findings are consistent with relatively toxin-insensitive channels including Na(V)1.7 being expressed in IB4 +ve neurones, whereas toxin sensitivity indicates that IB4 ve neurones may express Na(V)1.1 or Na(V)1.2, or both. The retention of excitability at low membrane potentials, and the responses to repetitive stimulation are explained by the known preferential expression of Na(V)1.8 in IB4 +ve neurones, and the reduction in action current in IB4 +ve neurones with repetitive stimulation supports a novel hypothesis explaining the slowing of conduction velocity in C-fibres by the build-up of Na(+) channel inactivation.

  8. Neuronal injury increases retrograde axonal transport of the neurotrophins to spinal sensory neurons and motor neurons via multiple receptor mechanisms.

    PubMed

    Curtis, R; Tonra, J R; Stark, J L; Adryan, K M; Park, J S; Cliffer, K D; Lindsay, R M; DiStefano, P S

    1998-10-01

    We investigated the retrograde axonal transport of 125I-labeled neurotrophins (NGF, BDNF, NT-3, and NT-4) from the sciatic nerve to dorsal root ganglion (DRG) sensory neurons and spinal motor neurons in normal rats or after neuronal injury. DRG neurons showed increased transport of all neurotrophins following crush injury to the sciatic nerve. This was maximal 1 day after sciatic nerve crush and returned to control levels after 7 days. 125I-BDNF transport from sciatic nerve was elevated with injection either proximal to the lesion or directly into the crush site and after transection of the dorsal roots. All neurotrophin transport was receptor-mediated and consistent with neurotrophin binding to the low-affinity neurotrophin receptor (LNR) or Trk receptors. However, transport of 125I-labeled wheat germ agglutinin also increased 1 day after sciatic nerve crush, showing that increased uptake and transport is a generalized response to injury in DRG sensory neurons. Spinal cord motor neurons also showed increased neurotrophin transport following sciatic nerve injury, although this was maximal after 3 days. The transport of 125I-NGF depended on the expression of LNR by injured motor neurons, as demonstrated by competition experiments with unlabeled neurotrophins. The absence of TrkA in normal motor neurons or after axotomy was confirmed by immunostaining and in situ hybridization. Thus, increased transport of neurotrophic factors after neuronal injury is due to multiple receptor-mediated mechanisms including general increases in axonal transport capacity. Copyright 1998 Academic Press.

  9. Local knockdown of the NaV1.6 sodium channel reduces pain behaviors, sensory neuron excitability, and sympathetic sprouting in rat models of neuropathic pain

    PubMed Central

    Xie, Wenrui; Strong, Judith A.; Zhang, Jun-Ming

    2015-01-01

    In the spinal nerve ligation model of neuropathic pain, as in other pain models, abnormal spontaneous activity of myelinated sensory neurons occurs early and is essential for establishing pain behaviors and other pathologies. Sympathetic sprouting into the dorsal root ganglion (DRG) is observed after spinal nerve ligation, and sympathectomy reduces pain behavior. Sprouting and spontaneous activity may be mutually reinforcing: blocking neuronal activity reduces sympathetic sprouting, and sympathetic spouts functionally increase spontaneous activity in vitro. However, most studies in this field have used nonspecific methods to block spontaneous activity, methods that also block evoked and normal activity. In this study, we injected small inhibitory RNA directed against the NaV1.6 sodium channel isoform into the DRG before spinal nerve ligation. This isoform can mediate high frequency repetitive firing, like that seen in spontaneously active neurons. Local knockdown of NaV1.6 markedly reduced mechanical pain behaviors induced by spinal nerve ligation, reduced sympathetic sprouting into the ligated sensory ganglion, and blocked abnormal spontaneous activity and other measures of hyperexcitability in myelinated neurons in the ligated sensory ganglion. Immunohistochemical experiments showed that sympathetic sprouting preferentially targeted NaV1.6-positive neurons. Under these experimental conditions, NaV1.6 knockdown did not prevent or strongly alter single evoked action potentials, unlike previous less specific methods used to block spontaneous activity. NaV1.6 knockdown also reduced pain behaviors in another pain model, chronic constriction of the sciatic nerve, provided the model was modified so that the lesion site was relatively close to the siRNA-injected lumbar DRGs. The results highlight the relative importance of abnormal spontaneous activity in establishing both pain behaviors and sympathetic sprouting, and suggest that the NaV1.6 isoform may have value as a

  10. Comparison of sensory tests and neuronal quantity of peripheral nerves between streptozotocin (STZ)-induced diabetic rats and paclitaxel (PAC)-treated rats.

    PubMed

    Jin, Heung Yong; Lee, Na Young; Ko, Hyun A; Lee, Kyung Ae; Park, Tae Sun

    Although diabetic peripheral neuropathy (DPN) and chemotherapy-induced peripheral neuropathy (CIPN) are different disease entities, they share similar neuropathic symptoms that impede quality of life for these patients. Despite having very similar downstream effects, there have been no direct comparisons between DPN and CIPN with respect to symptom severity and therapeutic responses. We compared peripheral nerve damage due to hyperglycemia with that caused by paclitaxel (PAC) treatment as represented by biochemical parameters, diverse sensory tests, and immunohistochemistry of cutaneous and sciatic nerves. The therapeutic effects of alpha-lipoic acid and DA-9801 were also compared in the two models. Animals were divided into seven groups (n = 7-10) as follows: normal, diabetes (DM), DM + alpha-lipoic acid 100 mg/kg (ALA), DM + DA-9801 (100 mg/kg), paclitaxel-treated rat (PAC), PAC + ALA (100 mg/kg), and PAC + DA-9801 (100 mg/kg). The sensory thresholds of animals to mechanical, heat, and pressure stimuli were altered by both hyperglycemia and PAC when compared with controls, and the responses to sensory tests were different between both groups. There were no significant differences in the biochemical markers of blood glutathione between DM and PAC groups (p > .05). Quantitative comparisons of peripheral nerves by intraepidermal nerve fiber density (IENFD) analysis indicated that the DM and PAC groups were similar (6.18 ± 1.03 vs. 5.01 ± 2.57). IENFD was significantly improved after ALA and DA-9801 treatment in diabetic animals (7.6 ± 1.28, 7.7 ± 1.28, respectively, p < .05) but did not reach significance in the PAC-treated groups (6.05 ± 1.76, 5.66 ± 1.26, respectively, p > .05). Sciatic nerves were less damaged in the PAC-treated groups compared with the DM groups with respect to axonal diameter and area (8.60 ± 1.14 μm vs. 6.66 ± 1.07 μm, and 59.04 ± 15.16 μm(2) vs. 35

  11. How can single sensory neurons predict behavior?

    PubMed Central

    Pitkow, Xaq; Liu, Sheng; Angelaki, Dora E.; DeAngelis, Gregory C.; Pouget, Alex

    2015-01-01

    Summary Single sensory neurons can be surprisingly predictive of behavior in discrimination tasks. We propose this is possible because sensory information extracted from neural populations is severely restricted, either by near-optimal decoding of a population with information-limiting correlations or suboptimal decoding that is blind to correlations. These have different consequences for choice correlations, the correlations between neural responses and behavioral choices. In the vestibular and cerebellar nuclei and the dorsal medial superior temporal area, we found that choice correlations during heading discrimination are consistent with near-optimal decoding of neuronal responses corrupted by information-limiting correlations. In the ventral intraparietal area, the choice correlations are also consistent with the presence of information-limiting correlations, but this area does not appear to influence behavior although the choice correlations are particularly large. These findings demonstrate how choice correlations can be used to assess the efficiency of the downstream read-out and detect the presence of information-limiting correlations. PMID:26182422

  12. Sensory neuron regulation of gastrointestinal inflammation and bacterial host defence.

    PubMed

    Lai, N Y; Mills, K; Chiu, I M

    2017-07-01

    Sensory neurons in the gastrointestinal tract have multifaceted roles in maintaining homeostasis, detecting danger and initiating protective responses. The gastrointestinal tract is innervated by three types of sensory neurons: dorsal root ganglia, nodose/jugular ganglia and intrinsic primary afferent neurons. Here, we examine how these distinct sensory neurons and their signal transducers participate in regulating gastrointestinal inflammation and host defence. Sensory neurons are equipped with molecular sensors that enable neuronal detection of diverse environmental signals including thermal and mechanical stimuli, inflammatory mediators and tissue damage. Emerging evidence shows that sensory neurons participate in host-microbe interactions. Sensory neurons are able to detect pathogenic and commensal bacteria through specific metabolites, cell-wall components, and toxins. Here, we review recent work on the mechanisms of bacterial detection by distinct subtypes of gut-innervating sensory neurons. Upon activation, sensory neurons communicate to the immune system to modulate tissue inflammation through antidromic signalling and efferent neural circuits. We discuss how this neuro-immune regulation is orchestrated through transient receptor potential ion channels and sensory neuropeptides including substance P, calcitonin gene-related peptide, vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide. Recent studies also highlight a role for sensory neurons in regulating host defence against enteric bacterial pathogens including Salmonella typhimurium, Citrobacter rodentium and enterotoxigenic Escherichia coli. Understanding how sensory neurons respond to gastrointestinal flora and communicate with immune cells to regulate host defence enhances our knowledge of host physiology and may form the basis for new approaches to treat gastrointestinal diseases. © 2017 The Association for the Publication of the Journal of Internal Medicine.

  13. Bistability, Noise and Information Processing in Sensory Neurons

    DTIC Science & Technology

    1993-11-01

    INFORMATION PROCESSING IN SENSORY PR: MA65 NEURONS . I PE: 0601153N 6. AUTHOR(S) WU: DN300034 A. R. Bulsara 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS...interpretation of time series data from firing events in periodically stimulated sensory neurons . A theoretical model, representing the neurons as bistable...Expert Systems, November 1993, pp. 11-14. DT70 QUALITY INSPECTED B 14 SUBJECT TERMS 15 NUMBER OF PAGES neural models single neurons stochastic

  14. Traumatic Brain Injury and Neuronal Functionality Changes in Sensory Cortex.

    PubMed

    Carron, Simone F; Alwis, Dasuni S; Rajan, Ramesh

    2016-01-01

    Traumatic brain injury (TBI), caused by direct blows to the head or inertial forces during relative head-brain movement, can result in long-lasting cognitive and motor deficits which can be particularly consequential when they occur in young people with a long life ahead. Much is known of the molecular and anatomical changes produced in TBI but much less is known of the consequences of these changes to neuronal functionality, especially in the cortex. Given that much of our interior and exterior lives are dependent on responsiveness to information from and about the world around us, we have hypothesized that a significant contributor to the cognitive and motor deficits seen after TBI could be changes in sensory processing. To explore this hypothesis, and to develop a model test system of the changes in neuronal functionality caused by TBI, we have examined neuronal encoding of simple and complex sensory input in the rat's exploratory and discriminative tactile system, the large face macrovibrissae, which feeds to the so-called "barrel cortex" of somatosensory cortex. In this review we describe the short-term and long-term changes in the barrel cortex encoding of whisker motion modeling naturalistic whisker movement undertaken by rats engaged in a variety of tasks. We demonstrate that the most common form of TBI results in persistent neuronal hyperexcitation specifically in the upper cortical layers, likely due to changes in inhibition. We describe the types of cortical inhibitory neurons and their roles and how selective effects on some of these could produce the particular forms of neuronal encoding changes described in TBI, and then generalize to compare the effects on inhibition seen in other forms of brain injury. From these findings we make specific predictions as to how non-invasive extra-cranial electrophysiology can be used to provide the high-precision information needed to monitor and understand the temporal evolution of changes in neuronal functionality

  15. Control of hair cell excitability by vestibular primary sensory neurons

    PubMed Central

    Brugeaud, Aurore; Travo, Cécile; Demêmes, Danielle; Lenoir, Marc; Llorens, Jordi; Puel, Jean-Luc; Chabbert, Christian

    2007-01-01

    In the rat utricle, synaptic contacts between hair cells and the nerve fibers arising from the vestibular primary neurons form during the first week after birth. During that period, the sodium-based excitability that characterizes neonate utricle sensory cells is switched off. To investigate whether the establishment of synaptic contacts was responsible for the modulation of the hair cell excitability, we used an organotypic culture of rat utricle in which the setting of synapses was prevented. Under this condition, the voltage-gated sodium current and the underlying action potentials persisted in a large proportion of non-afferented hair cells. We then studied whether impairment of nerve terminals in utricle of adult rats may also affect hair cell excitability. We induced selective and transient damages of afferent terminals using glutamate excitotoxicity in vivo. The efficiency of the excitotoxic injury was attested by selective swellings of the terminals and underlying altered vestibular behavior. Under this condition, the sodium-based excitability transiently recovered in hair cells. These results indicate that the modulation of hair cells excitability depends on the state of the afferent terminals. In adult utricle hair cells this property may be essential to set the conditions required for restoration of the sensory network after damage. This is achieved via re-expression of a biological process that occurs during synaptogenesis. PMID:17392466

  16. cAMP and cGMP contribute to sensory neuron hyperexcitability and hyperalgesia in rats with dorsal root ganglia compression.

    PubMed

    Song, Xue-Jun; Wang, Zheng-Bei; Gan, Qiang; Walters, Edgar T

    2006-01-01

    Numerous studies have implicated the cAMP-protein kinase A (PKA) pathway in producing hyperexcitability of dorsal root ganglia (DRG) sensory neurons under conditions associated with pain. Evidence is presented for roles of both the cAMP-PKA and cGMP-protein kinase G (PKG) pathways in maintaining neuronal hyperexcitability and behavioral hyperalgesia in a neuropathic pain model: chronic compression of the DRG (CCD treatment). Lumbar DRGs were compressed by a steel rod inserted into the intervertebral foramen. Thermal hyperalgesia was revealed by shortened latencies of foot withdrawal to radiant heat. Intracellular recordings were obtained in vitro from lumbar ganglia after in vivo DRG compression. Activators of the cAMP-PKA pathway, 8-Br-cAMP and Sp-cAMPS, and of the cGMP-PKG pathway, 8-Br-cGMP and Sp-cGMPS, increased the hyperexcitability of DRG neurons already produced by CCD treatment, as shown by further decreases in action potential threshold and increased repetitive discharge during depolarization. The adenylate cyclase inhibitor, SQ22536, the PKA antagonist, Rp-cAMPS, the guanylate cyclase inhibitor, ODQ, and the PKG inhibitor, Rp-8-pCPT-cGMPS, reduced the hyperexcitability of CCD DRG neurons. In vivo application of PKA and PKG antagonists transiently depressed behavioral hyperalgesia induced by CCD treatment. Unexpectedly, application of these agonists and antagonists to ganglia of naïve, uninjured animals had little effect on electrophysiological properties of DRG neurons and no effect on foot withdrawal, suggesting that sensitizing actions of these pathways in the DRG are enabled by prior injury or stress. The only effect observed in uncompressed ganglia was modest depolarization of DRG neurons by PKA and PKG agonists. CCD treatment also depolarized DRG neurons, but CCD-induced depolarization was not affected by agonists or antagonists of these pathways.

  17. Low-voltage-activated Ca2+ currents are generated by members of the CavT subunit family (alpha1G/H) in rat primary sensory neurons.

    PubMed

    Lambert, R C; McKenna, F; Maulet, Y; Talley, E M; Bayliss, D A; Cribbs, L L; Lee, J H; Perez-Reyes, E; Feltz, A

    1998-11-01

    Recently, two members of a new family of Ca2+ channel alpha1 subunits, alpha1G (or CavT.1) and alpha1H (or CavT.2), have been cloned and expressed. These alpha1 subunits generate Ba2+ currents similar to the T-type Ca2+ currents present in sensory neurons. Here, we use three methods to investigate whether the T currents of nodosus ganglion neurons are encoded by members of the CavT family. PCR detected the presence of mRNA encoding both alpha1G and alpha1H, as well as a third highly related sequence, alpha1I. In situ hybridizations performed on nodosus ganglia demonstrate a high expression of alpha1H subunit RNAs. Transfection of nodosus ganglion neurons with a generic antisense oligonucleotide against this new alpha1 subunit family selectively suppresses the low-voltage-activated Ca2+ current. The antisense oligonucleotide effect increased with time after transfection and reached a maximum 3 d after treatment, indicating a 2-3 d turnover for the alpha1 proteins. Taken together, these results suggest that the T-type current present in the sensory neurons is mainly attributable to alpha1H channels. In addition, taking advantage of the high specificity of the antisense ON to the cloned channels, we showed that T-type currents greatly slowed the repolarization occurring during an action potential and were responsible for up to 51% of the Ca2+ entry during spikes. Therefore, the antisense strategy clearly demonstrates the role of low-voltage-activated Ca2+ current in affecting the afterpotential properties and influencing the cell excitability. Such tools should be beneficial to further studies investigating physiological roles of T-type Ca2+ currents.

  18. System identification of Drosophila olfactory sensory neurons.

    PubMed

    Kim, Anmo J; Lazar, Aurel A; Slutskiy, Yevgeniy B

    2011-02-01

    The lack of a deeper understanding of how olfactory sensory neurons (OSNs) encode odors has hindered the progress in understanding the olfactory signal processing in higher brain centers. Here we employ methods of system identification to investigate the encoding of time-varying odor stimuli and their representation for further processing in the spike domain by Drosophila OSNs. In order to apply system identification techniques, we built a novel low-turbulence odor delivery system that allowed us to deliver airborne stimuli in a precise and reproducible fashion. The system provides a 1% tolerance in stimulus reproducibility and an exact control of odor concentration and concentration gradient on a millisecond time scale. Using this novel setup, we recorded and analyzed the in-vivo response of OSNs to a wide range of time-varying odor waveforms. We report for the first time that across trials the response of OR59b OSNs is very precise and reproducible. Further, we empirically show that the response of an OSN depends not only on the concentration, but also on the rate of change of the odor concentration. Moreover, we demonstrate that a two-dimensional (2D) Encoding Manifold in a concentration-concentration gradient space provides a quantitative description of the neuron's response. We then use the white noise system identification methodology to construct one-dimensional (1D) and two-dimensional (2D) Linear-Nonlinear-Poisson (LNP) cascade models of the sensory neuron for a fixed mean odor concentration and fixed contrast. We show that in terms of predicting the intensity rate of the spike train, the 2D LNP model performs on par with the 1D LNP model, with a root mean-square error (RMSE) increase of about 5 to 10%. Surprisingly, we find that for a fixed contrast of the white noise odor waveforms, the nonlinear block of each of the two models changes with the mean input concentration. The shape of the nonlinearities of both the 1D and the 2D LNP model appears to be

  19. Traumatic Brain Injury and Neuronal Functionality Changes in Sensory Cortex

    PubMed Central

    Carron, Simone F.; Alwis, Dasuni S.; Rajan, Ramesh

    2016-01-01

    Traumatic brain injury (TBI), caused by direct blows to the head or inertial forces during relative head-brain movement, can result in long-lasting cognitive and motor deficits which can be particularly consequential when they occur in young people with a long life ahead. Much is known of the molecular and anatomical changes produced in TBI but much less is known of the consequences of these changes to neuronal functionality, especially in the cortex. Given that much of our interior and exterior lives are dependent on responsiveness to information from and about the world around us, we have hypothesized that a significant contributor to the cognitive and motor deficits seen after TBI could be changes in sensory processing. To explore this hypothesis, and to develop a model test system of the changes in neuronal functionality caused by TBI, we have examined neuronal encoding of simple and complex sensory input in the rat’s exploratory and discriminative tactile system, the large face macrovibrissae, which feeds to the so-called “barrel cortex” of somatosensory cortex. In this review we describe the short-term and long-term changes in the barrel cortex encoding of whisker motion modeling naturalistic whisker movement undertaken by rats engaged in a variety of tasks. We demonstrate that the most common form of TBI results in persistent neuronal hyperexcitation specifically in the upper cortical layers, likely due to changes in inhibition. We describe the types of cortical inhibitory neurons and their roles and how selective effects on some of these could produce the particular forms of neuronal encoding changes described in TBI, and then generalize to compare the effects on inhibition seen in other forms of brain injury. From these findings we make specific predictions as to how non-invasive extra-cranial electrophysiology can be used to provide the high-precision information needed to monitor and understand the temporal evolution of changes in neuronal

  20. Identifying local and descending inputs for primary sensory neurons

    PubMed Central

    Zhang, Yi; Zhao, Shengli; Rodriguez, Erica; Takatoh, Jun; Han, Bao-Xia; Zhou, Xiang; Wang, Fan

    2015-01-01

    Primary pain and touch sensory neurons not only detect internal and external sensory stimuli, but also receive inputs from other neurons. However, the neuronal derived inputs for primary neurons have not been systematically identified. Using a monosynaptic rabies viruses–based transneuronal tracing method combined with sensory-specific Cre-drivers, we found that sensory neurons receive intraganglion, intraspinal, and supraspinal inputs, the latter of which are mainly derived from the rostroventral medulla (RVM). The viral-traced central neurons were largely inhibitory but also consisted of some glutamatergic neurons in the spinal cord and serotonergic neurons in the RVM. The majority of RVM-derived descending inputs were dual GABAergic and enkephalinergic (opioidergic). These inputs projected through the dorsolateral funiculus and primarily innervated layers I, II, and V of the dorsal horn, where pain-sensory afferents terminate. Silencing or activation of the dual GABA/enkephalinergic RVM neurons in adult animals substantially increased or decreased behavioral sensitivity, respectively, to heat and mechanical stimuli. These results are consistent with the fact that both GABA and enkephalin can exert presynaptic inhibition of the sensory afferents. Taken together, this work provides a systematic view of and a set of tools for examining peri- and extrasynaptic regulations of pain-afferent transmission. PMID:26426077

  1. Spinal sensory projection neuron responses to spinal cord stimulation are mediated by circuits beyond gate control

    PubMed Central

    Zhang, Tianhe C.; Janik, John J.; Peters, Ryan V.; Chen, Gang; Ji, Ru-Rong

    2015-01-01

    Spinal cord stimulation (SCS) is a therapy used to treat intractable pain with a putative mechanism of action based on the Gate Control Theory. We hypothesized that sensory projection neuron responses to SCS would follow a single stereotyped response curve as a function of SCS frequency, as predicted by the Gate Control circuit. We recorded the responses of antidromically identified sensory projection neurons in the lumbar spinal cord during 1- to 150-Hz SCS in both healthy rats and neuropathic rats following chronic constriction injury (CCI). The relationship between SCS frequency and projection neuron activity predicted by the Gate Control circuit accounted for a subset of neuronal responses to SCS but could not account for the full range of observed responses. Heterogeneous responses were classifiable into three additional groups and were reproduced using computational models of spinal microcircuits representing other interactions between nociceptive and nonnociceptive sensory inputs. Intrathecal administration of bicuculline, a GABAA receptor antagonist, increased spontaneous and evoked activity in projection neurons, enhanced excitatory responses to SCS, and reduced inhibitory responses to SCS, suggesting that GABAA neurotransmission plays a broad role in regulating projection neuron activity. These in vivo and computational results challenge the Gate Control Theory as the only mechanism underlying SCS and refine our understanding of the effects of SCS on spinal sensory neurons within the framework of contemporary understanding of dorsal horn circuitry. PMID:25972582

  2. Intraganglionic interactions between satellite cells and adult sensory neurons.

    PubMed

    Christie, Kimberly; Koshy, Dilip; Cheng, Chu; Guo, GuiFang; Martinez, Jose A; Duraikannu, Arul; Zochodne, Douglas W

    2015-07-01

    Perineuronal satellite cells have an intimate anatomical relationship with sensory neurons that suggests close functional collaboration and mutual support. We examined several facets of this relationship in adult sensory dorsal root ganglia (DRG). Collaboration included the support of process outgrowth by clustering of satellite cells, induction of distal branching behavior by soma signaling, the capacity of satellite cells to respond to distal axon injury of its neighboring neurons, and evidence of direct neuron-satellite cell exchange. In vitro, closely adherent coharvested satellite cells routinely clustered around new outgrowing processes and groups of satellite cells attracted neurite processes. Similar clustering was encountered in the pseudounipolar processes of intact sensory neurons within intact DRG in vivo. While short term exposure of distal growth cones of unselected adult sensory neurons to transient gradients of a PTEN inhibitor had negligible impacts on their behavior, exposure of the soma induced early and substantial growth of their distant neurites and branches, an example of local soma signaling. In turn, satellite cells sensed when distal neuronal axons were injured by enlarging and proliferating. We also observed that satellite cells were capable of internalizing and expressing a neuron fluorochrome label, diamidino yellow, applied remotely to distal injured axons of the neuron and retrogradely transported to dorsal root ganglia sensory neurons. The findings illustrate a robust interaction between intranganglionic neurons and glial cells that involve two way signals, features that may be critical for both regenerative responses and ongoing maintenance.

  3. GluN2B NMDA receptor and excitatory amino acid transporter 3 are upregulated in primary sensory neurons after seven days of morphine administration in rats: implication for opiate-induced hyperalgesia

    PubMed Central

    Gong, Kerui; Bhargava, Aditi; Jasmin, Luc

    2016-01-01

    The contribution of the peripheral nervous system to opiate-induced hyperalgesia (OIH) is not well understood. Here, we determined the changes in excitability of primary sensory neurons after sustained morphine administration for 7 days. Changes in expression of glutamate receptors and glutamate transporters after morphine administration were ascertained in dorsal root ganglions (DRGs). Patch clamp recordings from intact DRGs (ex-vivo preparation) of morphine-treated rats showed increased excitability of small diameter (≤ 30 μm) neurons with respect to rheobase and membrane threshold, whereas the excitability of large diameter (> 30 μm) neurons remained unchanged. Small diameter neurons also displayed increased responses to glutamate, which were mediated mainly by GluN2B containing NMDA receptors (NMDARs), and to a lesser degree by the neuronal excitatory amino acid transporter 3 /excitatory amino acid carrier 1 (EAAT3/EAAC1). Co-administration in vivo of the GluN2B selective antagonist Ro 25-6981 with morphine for 7 days prevented the appearance of OIH and increased morphine-induced analgesia. Administration of morphine for 7 days led to an increased expression of GluN2B and EAAT3/EAAC1, but not of the AMPA, kainate or Group I metabotropic glutamate receptors, or of the vesicular glutamate transporter 2 (VGLUT2). These results suggest that peripheral glutamatergic neurotransmission contributes to OIH and that GluN2B subunit of NMDARs in the periphery may be a target for therapy. PMID:26335908

  4. Capsaicin and sensory neurones: a historical perspective.

    PubMed

    Szolcsányi, János

    2014-01-01

    Capsaicin, the pungent ingredient of red pepper has become not only a "hot" topic in neuroscience but its new target-related unique actions have opened the door for the drug industry to introduce a new chapter of analgesics. After several lines of translational efforts with over 1,000 patents and clinical trials, the 8% capsaicin dermal patch reached the market and its long-lasting local analgesic effect in some severe neuropathic pain states is now well established. This introductory chapter outlines on one hand the historical background based on the author's 50 years of experience in this field and on the other hand emphasizes new scopes, fascinating perspectives in pharmaco-physiology, and molecular pharmacology of nociceptive sensory neurons. Evidence for the effect of capsaicin on C-polymodal nociceptors (CMH), C-mechanoinsensitive (CHMi), and silent C-nociceptors are listed and the features of the capsaicin-induced blocking effects of nociceptors are demonstrated. Common and different characteristics of nociceptor-blocking actions after systemic, perineural, local, intrathecal, and in vitro treatments are summarized. Evidence for the misleading conclusions drawn from neonatal capsaicin pretreatment is presented. Perspectives opened from cloning the capsaicin receptor "Transient Receptor Potential Vanilloid 1" (TRPV1) are outlined and potential molecular mechanisms behind the long-lasting functional, ultrastructural, and nerve terminal-damaging effects of capsaicin and other TRPV1 agonists are summarized. Neurogenic inflammation and the long-list of "capsaicin-sensitive" tissue responses are mediated by an unorthodox dual sensory-efferent function of peptidergic TRPV1-expressing nerve terminals which differ from the classical efferent and sensory nerve endings that have a unidirectional role in neuroregulation. Thermoregulatory effects of capsaicin are discussed in detail. It is suggested that since hyperthermia and burn risk due to enhanced noxious heat

  5. Opening of pannexin- and connexin-based channels increases the excitability of nodose ganglion sensory neurons

    PubMed Central

    Retamal, Mauricio A.; Alcayaga, Julio; Verdugo, Christian A.; Bultynck, Geert; Leybaert, Luc; Sáez, Pablo J.; Fernández, Ricardo; León, Luis E.; Sáez, Juan C.

    2014-01-01

    Satellite glial cells (SGCs) are the main glia in sensory ganglia. They surround neuronal bodies and form a cap that prevents the formation of chemical or electrical synapses between neighboring neurons. SGCs have been suggested to establish bidirectional paracrine communication with sensory neurons. However, the molecular mechanism involved in this cellular communication is unknown. In the central nervous system (CNS), astrocytes present connexin43 (Cx43) hemichannels and pannexin1 (Panx1) channels, and the opening of these channels allows the release of signal molecules, such as ATP and glutamate. We propose that these channels could play a role in glia-neuron communication in sensory ganglia. Therefore, we studied the expression and function of Cx43 and Panx1 in rat and mouse nodose-petrosal-jugular complexes (NPJcs) using confocal immunofluorescence, molecular and electrophysiological techniques. Cx43 and Panx1 were detected in SGCs and in sensory neurons, respectively. In the rat and mouse, the electrical activity of vagal nerve increased significantly after nodose neurons were exposed to a Ca2+/Mg2+-free solution, a condition that increases the open probability of Cx hemichannels. This response was partially mimicked by a cell-permeable peptide corresponding to the last 10 amino acids of Cx43 (TAT-Cx43CT). Enhanced neuronal activity was reduced by Cx hemichannel, Panx1 channel and P2X7 receptor blockers. Moreover, the role of Panx1 was confirmed in NPJc, because in those from Panx1 knockout mice showed a reduced increase of neuronal activity induced by Ca2+/Mg2+-free extracellular conditions. The data suggest that Cx hemichannels and Panx channels serve as paracrine communication pathways between SGCs and neurons by modulating the excitability of sensory neurons. PMID:24999316

  6. Opening of pannexin- and connexin-based channels increases the excitability of nodose ganglion sensory neurons.

    PubMed

    Retamal, Mauricio A; Alcayaga, Julio; Verdugo, Christian A; Bultynck, Geert; Leybaert, Luc; Sáez, Pablo J; Fernández, Ricardo; León, Luis E; Sáez, Juan C

    2014-01-01

    Satellite glial cells (SGCs) are the main glia in sensory ganglia. They surround neuronal bodies and form a cap that prevents the formation of chemical or electrical synapses between neighboring neurons. SGCs have been suggested to establish bidirectional paracrine communication with sensory neurons. However, the molecular mechanism involved in this cellular communication is unknown. In the central nervous system (CNS), astrocytes present connexin43 (Cx43) hemichannels and pannexin1 (Panx1) channels, and the opening of these channels allows the release of signal molecules, such as ATP and glutamate. We propose that these channels could play a role in glia-neuron communication in sensory ganglia. Therefore, we studied the expression and function of Cx43 and Panx1 in rat and mouse nodose-petrosal-jugular complexes (NPJcs) using confocal immunofluorescence, molecular and electrophysiological techniques. Cx43 and Panx1 were detected in SGCs and in sensory neurons, respectively. In the rat and mouse, the electrical activity of vagal nerve increased significantly after nodose neurons were exposed to a Ca(2+)/Mg(2+)-free solution, a condition that increases the open probability of Cx hemichannels. This response was partially mimicked by a cell-permeable peptide corresponding to the last 10 amino acids of Cx43 (TAT-Cx43CT). Enhanced neuronal activity was reduced by Cx hemichannel, Panx1 channel and P2X7 receptor blockers. Moreover, the role of Panx1 was confirmed in NPJc, because in those from Panx1 knockout mice showed a reduced increase of neuronal activity induced by Ca(2+)/Mg(2+)-free extracellular conditions. The data suggest that Cx hemichannels and Panx channels serve as paracrine communication pathways between SGCs and neurons by modulating the excitability of sensory neurons.

  7. Lysophosphatidic acid and signaling in sensory neurons.

    PubMed

    Oude Elferink, Ronald P J; Bolier, Ruth; Beuers, Ulrich H

    2015-01-01

    Lysophosphatidic acid is a potent signaling lipid molecule that has initially been characterized as a growth factor. However, later studies have revealed many more functions such as modulation of cell shape, cell migration, prevention of apoptosis, platelet aggregation, wound healing, osteoclast differentiation, vasopressor activity, embryo implantation, angiogenesis, lung fibrosis, hair growth and more. The molecule mainly acts through the activation of a set of at least 6 G-protein-coupled receptors (LPA1-6), but intracellular LPA was also shown to signal through the activation of the nuclear receptor PPARγ. In this short review we discuss the recent observations which suggest that in pathological conditions LPA also modulates signaling in sensory neurons. Thus, LPA has been shown to play a role in the initiation of neuropathic pain and, more recently, a relation was observed between increased LPA levels in the circulation and cholestatic itch. The mechanism by which this occurs remains to be elucidated. This article is part of a Special Issue entitled Linking transcription to physiology in lipodomics. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Large Intercalated Neurons of Amygdala Relay Noxious Sensory Information

    PubMed Central

    Bienvenu, Thomas C.M.; Busti, Daniela; Micklem, Benjamin R.; Mansouri, Mahnaz; Magill, Peter J.

    2015-01-01

    Various GABAergic neuron types of the amygdala cooperate to control principal cell firing during fear-related and other behaviors, and understanding their specialized roles is important. Among GABAergic neurons, the so-called intercalated cells (ITCcs) are critically involved in the expression and extinction of fear memory. Tightly clustered small-sized spiny neurons constitute the majority of ITCcs, but they are surrounded by sparse, larger neurons (L-ITCcs) for which very little information is known. We report here a detailed neurochemical, structural and physiological characterization of rat L-ITCcs, as identified with juxtacellular recording/labeling in vivo. We supplement these data with anatomical and neurochemical analyses of nonrecorded L-ITCcs. We demonstrate that L-ITCcs are GABAergic, and strongly express metabotropic glutamate receptor 1α and GABAA receptor α1 subunit, together with moderate levels of parvalbumin. Furthermore, L-ITCcs are innervated by fibers enriched with metabotropic glutamate receptors 7a and/or 8a. In contrast to small-sized spiny ITCcs, L-ITCcs possess thick, aspiny dendrites, have highly branched, long-range axonal projections, and innervate interneurons in the basolateral amygdaloid complex. The axons of L-ITCcs also project to distant brain areas, such as the perirhinal, entorhinal, and endopiriform cortices. In vivo recorded L-ITCcs are strongly activated by noxious stimuli, such as hindpaw pinches or electrical footshocks. Consistent with this, we observed synaptic contacts on L-ITCc dendrites from nociceptive intralaminar thalamic nuclei. We propose that, during salient sensory stimulation, L-ITCcs disinhibit local and distant principal neurons, acting as “hub cells,” to orchestrate the activity of a distributed network. PMID:25653362

  9. TrkB agonist antibody pretreatment enhances neuronal survival and long-term sensory motor function following hypoxic ischemic injury in neonatal rats.

    PubMed

    Kim, Gab Seok; Cho, Seongeun; Nelson, James W; Zipfel, Gregory J; Han, Byung Hee

    2014-01-01

    Perinatal hypoxic ischemia (H-I) causes brain damage and long-term neurological impairments, leading to motor dysfunctions and cerebral palsy. Many studies have demonstrated that the TrkB-ERK1/2 signaling pathway plays a key role in mediating the protective effect of brain-derived neurotrophic factor (BDNF) following perinatal H-I brain injury in experimental animals. In the present study, we explored the neuroprotective effects of the TrkB-specific agonist monoclonal antibody 29D7 on H-I brain injury in neonatal rats. First, we found that intracerebroventricular (icv) administration of 29D7 in normal P7 rats markedly increased the levels of phosphorylated ERK1/2 and phosphorylated AKT in neurons up to 24 h. Second, P7 rats received icv administration of 29D7 and subjected to H-I injury induced by unilateral carotid artery ligation and exposure to hypoxia (8% oxygen). We found that 29D7, to a similar extent to BDNF, significantly inhibited activation of caspase-3, a biochemical hallmark of apoptosis, following H-I injury. Third, we found that this 29D7-mediated neuroprotective action persisted at least up to 5 weeks post-H-I injury as assessed by brain tissue loss, implicating long-term neurotrophic effects rather than an acute delay of cell death. Moreover, the long-term neuroprotective effect of 29D7 was tightly correlated with sensorimotor functional recovery as assessed by a tape-removal test, while 29D7 did not significantly improve rotarod performance. Taken together, these findings demonstrate that pretreatment with the TrkB-selective agonist 29D7 significantly increases neuronal survival and behavioral recovery following neonatal hypoxic-ischemic brain injury.

  10. Sensory Neuron-Specific Deletion of TRPA1 Results in Mechanical Cutaneous Sensory Deficits.

    PubMed

    Zappia, Katherine J; O'Hara, Crystal L; Moehring, Francie; Kwan, Kelvin Y; Stucky, Cheryl L

    2017-01-01

    The nonselective cation channel transient receptor potential ankyrin 1 (TRPA1) is known to be a key contributor to both somatosensation and pain. Recent studies have implicated TRPA1 in additional physiologic functions and have also suggested that TRPA1 is expressed in nonneuronal tissues. Thus, it has become necessary to resolve the importance of TRPA1 expressed in primary sensory neurons, particularly since previous research has largely used global knock-out animals and chemical TRPA1 antagonists. We therefore sought to isolate the physiological relevance of TRPA1 specifically within sensory neurons. To accomplish this, we used Advillin-Cre mice, in which the promoter for Advillin is used to drive expression of Cre recombinase specifically within sensory neurons. These Advillin-Cre mice were crossed with Trpa1(fl/fl) mice to generate sensory neuron-specific Trpa1 knock-out mice. Here, we show that tissue-specific deletion of TRPA1 from sensory neurons produced strong deficits in behavioral sensitivity to mechanical stimulation, while sensitivity to cold and heat stimuli remained intact. The mechanical sensory deficit was incomplete compared to the mechanosensory impairment of TRPA1 global knock-out mice, in line with the incomplete (∼80%) elimination of TRPA1 from sensory neurons in the tissue-specific Advillin-Cre knock-out mice. Equivalent findings were observed in tissue-specific knock-out animals originating from two independently-generated Advillin-Cre lines. As such, our results show that sensory neuron TRPA1 is required for mechanical, but not cold, responsiveness in noninjured skin.

  11. Sensory Neuron-Specific Deletion of TRPA1 Results in Mechanical Cutaneous Sensory Deficits

    PubMed Central

    2017-01-01

    Abstract The nonselective cation channel transient receptor potential ankyrin 1 (TRPA1) is known to be a key contributor to both somatosensation and pain. Recent studies have implicated TRPA1 in additional physiologic functions and have also suggested that TRPA1 is expressed in nonneuronal tissues. Thus, it has become necessary to resolve the importance of TRPA1 expressed in primary sensory neurons, particularly since previous research has largely used global knock-out animals and chemical TRPA1 antagonists. We therefore sought to isolate the physiological relevance of TRPA1 specifically within sensory neurons. To accomplish this, we used Advillin-Cre mice, in which the promoter for Advillin is used to drive expression of Cre recombinase specifically within sensory neurons. These Advillin-Cre mice were crossed with Trpa1fl/fl mice to generate sensory neuron-specific Trpa1 knock-out mice. Here, we show that tissue-specific deletion of TRPA1 from sensory neurons produced strong deficits in behavioral sensitivity to mechanical stimulation, while sensitivity to cold and heat stimuli remained intact. The mechanical sensory deficit was incomplete compared to the mechanosensory impairment of TRPA1 global knock-out mice, in line with the incomplete (∼80%) elimination of TRPA1 from sensory neurons in the tissue-specific Advillin-Cre knock-out mice. Equivalent findings were observed in tissue-specific knock-out animals originating from two independently-generated Advillin-Cre lines. As such, our results show that sensory neuron TRPA1 is required for mechanical, but not cold, responsiveness in noninjured skin. PMID:28303259

  12. NKCC1 Activation Is Required for Myelinated Sensory Neurons Regeneration through JNK-Dependent Pathway.

    PubMed

    Mòdol, Laura; Santos, Daniel; Cobianchi, Stefano; González-Pérez, Francisco; López-Alvarez, Víctor; Navarro, Xavier

    2015-05-13

    After peripheral nerve injury, axons are able to regenerate, although specific sensory reinnervation and functional recovery are usually worse for large myelinated than for small sensory axons. The mechanisms that mediate the regeneration of different sensory neuron subpopulations are poorly known. The Na(+)-K(+)-Cl(-) cotransporter 1 (NKCC1) is particularly relevant in setting the intracellular chloride concentration. After axotomy, increased NKCC1 phosphorylation has been reported to be important for neurite outgrowth of sensory neurons; however, the mechanisms underlying its effects are still unknown. In the present study we used in vitro and in vivo models to assess the differential effects of blocking NKCC1 activity on the regeneration of different types of dorsal root ganglia (DRGs) neurons after sciatic nerve injury in the rat. We observed that blocking NKCC1 activity by bumetanide administration induces a selective effect on neurite outgrowth and regeneration of myelinated fibers without affecting unmyelinated DRG neurons. To further study the mechanism underlying NKCC1 effects, we also assessed the changes in mitogen-activated protein kinase (MAPK) signaling under NKCC1 modulation. The inhibition of NKCC1 activity in vitro and in vivo modified pJNK1/2/3 expression in DRG neurons. Together, our study identifies a mechanism selectively contributing to myelinated axon regeneration, and point out the role of Cl(-) modulation in DRG neuron regeneration and in the activation of MAPKs, particularly those belonging to the JNK family. Copyright © 2015 the authors 0270-6474/15/357414-14$15.00/0.

  13. Dicer maintains the identity and function of proprioceptive sensory neurons.

    PubMed

    O'Toole, Sean M; Ferrer, Monica M; Mekonnen, Jennifer; Zhang, Haihan; Shima, Yasuyuki; Ladle, David R; Nelson, Sacha B

    2017-03-01

    Neuronal cell identity is established during development and must be maintained throughout an animal's life (Fishell G, Heintz N. Neuron 80: 602-612, 2013). Transcription factors critical for establishing neuronal identity can be required for maintaining it (Deneris ES, Hobert O. Nat Neurosci 17: 899-907, 2014). Posttranscriptional regulation also plays an important role in neuronal differentiation (Bian S, Sun T. Mol Neurobiol 44: 359-373, 2011), but its role in maintaining cell identity is less established. To better understand how posttranscriptional regulation might contribute to cell identity, we examined the proprioceptive neurons in the dorsal root ganglion (DRG), a highly specialized sensory neuron class, with well-established properties that distinguish them from other neurons in the ganglion. By conditionally ablating Dicer in mice, using parvalbumin (Pvalb)-driven Cre recombinase, we impaired posttranscriptional regulation in the proprioceptive sensory neuron population. Knockout (KO) animals display a progressive form of ataxia at the beginning of the fourth postnatal week that is accompanied by a cell death within the DRG. Before cell loss, expression profiling shows a reduction of proprioceptor specific genes and an increased expression of nonproprioceptive genes normally enriched in other ganglion neurons. Furthermore, although central connections of these neurons are intact, the peripheral connections to the muscle are functionally impaired. Posttranscriptional regulation is therefore necessary to retain the transcriptional identity and support functional specialization of the proprioceptive sensory neurons.NEW & NOTEWORTHY We have demonstrated that selectively impairing Dicer in parvalbumin-positive neurons, which include the proprioceptors, triggers behavioral changes, a lack of muscle connectivity, and a loss of transcriptional identity as observed through RNA sequencing. These results suggest that Dicer and, most likely by extension, micro

  14. Orofacial sensory changes after streptozotocin-induced diabetes in rats.

    PubMed

    Nones, Carina Fernanda Mattedi; Reis, Renata Cristiane; Jesus, Carlos Henrique Alves; Veronez, Djanira Aparecida da Luz; Cunha, Joice Maria; Chichorro, Juliana Geremias

    2013-03-21

    Peripheral neuropathy is a common complication of diabetes and is often accompanied by episodes of pain. There is evidence that diabetic neuropathy may affect the trigeminal nerve, altering the transmission of orofacial sensory information. Structural changes in the trigeminal ganglia may be involved in the development of these sensory alterations. Herein, we evaluate the development of orofacial sensory changes after streptozotocin-induced diabetes in rats, and their sensitivity to pregabalin and morphine treatments. Furthermore, stereological analysis of the trigeminal ganglia was performed. Diabetic rats showed similar responses to 1% formalin applied into the upper lip compared to normoglycemic rats on weeks 1, 2 and 4 after streptozotocin. Additionally, there was no difference in the facial mechanical threshold of normoglycemic and diabetic rats, on weeks 1 up to 5 after streptozotocin, while the paw mechanical threshold of diabetic rats was significantly reduced. In contrast, diabetic rats developed long-lasting orofacial heat and cold hyperalgesia. Moreover, stereological analyses revealed significant neuronal loss in the trigeminal ganglia of diabetic compared to normoglycemic rats. Pregabalin treatment (30mg/kg, p.o.) of diabetic rats resulted in marked and prolonged (up to 6h) reduction of heat and cold orofacial hyperalgesia. Likewise, morphine treatment (2.5mg/kg, s.c.) abolished orofacial heat and cold hyperalgesia, but its effect was significant only up to 1h after the administration. In conclusion, the results of the present study demonstrated that streptozotocin-treated rats developed long-lasting orofacial heat and cold hyperalgesia, which is more amenable to reduction by pregabalin than morphine.

  15. Cytokine and Chemokine Regulation of Sensory Neuron Function

    PubMed Central

    Miller, Richard J.; Jung, Hosung; Bhangoo, Sonia K.; White, Fletcher A.

    2009-01-01

    Pain normally subserves a vital role in the survival of the organism, prompting the avoidance of situations associated with tissue damage. However, the sensation of pain can become dissociated from its normal physiological role. In conditions of neuropathic pain, spontaneous or hypersensitive pain behavior occurs in the absence of the appropriate stimuli. Our incomplete understanding of the mechanisms underlying chronic pain hypersensitivity accounts for the general ineffectiveness of currently available options for the treatment of chronic pain syndromes. Despite its complex pathophysiological nature, it is clear that neuropathic pain is associated with short- and long-term changes in the excitability of sensory neurons in the dorsal root ganglia (DRG) as well as their central connections. Recent evidence suggests that the upregulated expression of inflammatory cytokines in association with tissue damage or infection triggers the observed hyperexcitability of pain sensory neurons. The actions of inflammatory cytokines synthesized by DRG neurons and associated glial cells, as well as by astrocytes and microglia in the spinal cord, can produce changes in the excitability of nociceptive sensory neurons. These changes include rapid alterations in the properties of ion channels expressed by these neurons, as well as longer-term changes resulting from new gene transcription. In this chapter we review the diverse changes produced by inflammatory cytokines in the behavior of sensory neurons in the context of chronic pain syndromes. PMID:19655114

  16. Activation of TRPV4 Regulates Respiration through Indirect Activation of Bronchopulmonary Sensory Neurons

    PubMed Central

    Gu, Qihai (David); Moss, Charles R.; Kettelhut, Kristen L.; Gilbert, Carolyn A.; Hu, Hongzhen

    2016-01-01

    Transient receptor potential vanilloid receptor 4 (TRPV4) is a calcium-permeable non-selective cation channel implicated in numerous physiological and pathological functions. This study aimed to investigate the effect of TRPV4 activation on respiration and to explore the potential involvement of bronchopulmonary sensory neurons. Potent TRPV4 agonist GSK1016790A was injected into right atrium in anesthetized spontaneously breathing rats and the changes in breathing were measured. Patch-clamp recording was performed to investigate the effect of GSK1016790A or another TRPV4 activator 4α-PDD on cultured rat vagal bronchopulmonary sensory neurons. Immunohistochemistry was carried out to determine the TRPV4-expressing cells in lung slices obtained from TRPV4-EGFP mice. Our results showed, that right-atrial injection of GSK1016790A evoked a slow-developing, long-lasting rapid shallow breathing in anesthetized rats. Activation of TRPV4 also significantly potentiated capsaicin-evoked chemoreflex responses. The alteration in ventilation induced by GSK1016790A was abolished by cutting or perineural capsaicin treatment of both vagi, indicating the involvement of bronchopulmonary afferent neurons. The stimulating and sensitizing effects of GSK1016790A were abolished by a selective TRPV4 antagonist GSK2193874 and also by inhibiting cyclooxygenase with indomethacin. Surprising, GSK1016790A or 4α-PDD did not activate isolated bronchopulmonary sensory neurons, nor did they modulate capsaicin-induced inward currents in these neurons. Furthermore, TRPV4 expression was found in alveolar macrophages, alveolar epithelial, and vascular endothelial cells. Collectively, our results suggest that GSK1016790A regulates the respiration through an indirect activation of bronchopulmonary sensory neurons, likely via its stimulation of other TRPV4-expressing cells in the lungs and airways. PMID:26973533

  17. Activation of TRPV4 Regulates Respiration through Indirect Activation of Bronchopulmonary Sensory Neurons.

    PubMed

    Gu, Qihai David; Moss, Charles R; Kettelhut, Kristen L; Gilbert, Carolyn A; Hu, Hongzhen

    2016-01-01

    Transient receptor potential vanilloid receptor 4 (TRPV4) is a calcium-permeable non-selective cation channel implicated in numerous physiological and pathological functions. This study aimed to investigate the effect of TRPV4 activation on respiration and to explore the potential involvement of bronchopulmonary sensory neurons. Potent TRPV4 agonist GSK1016790A was injected into right atrium in anesthetized spontaneously breathing rats and the changes in breathing were measured. Patch-clamp recording was performed to investigate the effect of GSK1016790A or another TRPV4 activator 4α-PDD on cultured rat vagal bronchopulmonary sensory neurons. Immunohistochemistry was carried out to determine the TRPV4-expressing cells in lung slices obtained from TRPV4-EGFP mice. Our results showed, that right-atrial injection of GSK1016790A evoked a slow-developing, long-lasting rapid shallow breathing in anesthetized rats. Activation of TRPV4 also significantly potentiated capsaicin-evoked chemoreflex responses. The alteration in ventilation induced by GSK1016790A was abolished by cutting or perineural capsaicin treatment of both vagi, indicating the involvement of bronchopulmonary afferent neurons. The stimulating and sensitizing effects of GSK1016790A were abolished by a selective TRPV4 antagonist GSK2193874 and also by inhibiting cyclooxygenase with indomethacin. Surprising, GSK1016790A or 4α-PDD did not activate isolated bronchopulmonary sensory neurons, nor did they modulate capsaicin-induced inward currents in these neurons. Furthermore, TRPV4 expression was found in alveolar macrophages, alveolar epithelial, and vascular endothelial cells. Collectively, our results suggest that GSK1016790A regulates the respiration through an indirect activation of bronchopulmonary sensory neurons, likely via its stimulation of other TRPV4-expressing cells in the lungs and airways.

  18. Regeneration and rewiring of rodent olfactory sensory neurons.

    PubMed

    Yu, C Ron; Wu, Yunming

    2017-01-01

    The olfactory sensory neurons are the only neurons in the mammalian nervous system that not only regenerate naturally and in response to injury, but also project to specific targets in the brain. The stem cells in the olfactory epithelium commit to both neuronal and non-neuronal lineages depending on the environmental conditions. They provide a continuous supply of new neurons. A newly generated neuron must express a specific odorant receptor gene and project to a central target consist of axons expressing the same receptor type. Recent studies have provided insights into this highly regulated, complex process. However, the molecular mechanisms that determine the regenerative capacity of stem cells, and the ability of newly generated neurons in directing their axons toward specific targets, remain elusive. Here we review progresses and controversies in the field and offer testable models. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. IPP5 inhibits neurite growth in primary sensory neurons by maintaining TGF-β/Smad signaling.

    PubMed

    Han, Qing-Jian; Gao, Nan-Nan; Guo-QiangMa; Zhang, Zhen-Ning; Yu, Wen-Hui; Pan, Jing; Wang, Qiong; Zhang, Xu; Bao, Lan

    2013-01-15

    During nerve regeneration, neurite growth is regulated by both intrinsic molecules and extracellular factors. Here, we found that inhibitor 5 of protein phosphatase 1 (IPP5), a newly identified inhibitory subunit of protein phosphatase 1 (PP1), inhibited neurite growth in primary sensory neurons as an intrinsic regulator. IPP5 was highly expressed in the primary sensory neurons of rat dorsal root ganglion (DRG) and was downregulated after sciatic nerve axotomy. Knocking down IPP5 with specific shRNA increased the length of the longest neurite, the total neurite length and the number of neurite ends in cultured rat DRG neurons. Mutation of the PP1-docking motif K(8)IQF(11) or the PP1-inhibiting motif at Thr(34) eliminated the IPP5-induced inhibition of neurite growth. Furthermore, biochemical experiments showed that IPP5 interacted with type I transforming growth factor-β receptor (TβRI) and PP1 and enhanced transforming growth factor-β (TGF-β)/Smad signaling in a PP1-dependent manner. Overexpressing IPP5 in DRG neurons aggravated TGF-β-induced inhibition of neurite growth, which was abolished by blocking PP1 or IPP5 binding to PP1. Blockage of TGF-β signaling with the TβRI inhibitor SB431542 or Smad2 shRNA attenuated the IPP5-induced inhibition of neurite growth. Thus, these data indicate that selectively expressed IPP5 inhibits neurite growth by maintaining TGF-β signaling in primary sensory neurons.

  20. Effects of odor stimulation on antidromic spikes in olfactory sensory neurons.

    PubMed

    Scott, John W; Sherrill, Lisa

    2008-12-01

    Spikes were evoked in rat olfactory sensory neuron (OSN) populations by electrical stimulation of the olfactory bulb nerve layer in pentobarbital anesthetized rats. The latencies and recording positions for these compound spikes showed that they originated in olfactory epithelium. Dual simultaneous recordings indicated conduction velocities in the C-fiber range, around 0.5 m/s. These spikes are concluded to arise from antidromically activated olfactory sensory neurons. Electrical stimulation at 5 Hz was used to track changes in the size and latency of the antidromic compound population spike during the odor response. Strong odorant stimuli suppressed the spike size and prolonged its latency. The latency was prolonged throughout long odor stimuli, indicating continued activation of olfactory receptor neuron axons. The amounts of spike suppression and latency change were strongly correlated with the electroolfactogram (EOG) peak size evoked at the same site across odorants and across stimulus intensities. We conclude that the curve of antidromic spike suppression gives a reasonable representation of spiking activity in olfactory sensory neurons driven by odorants and that the correlation of peak spike suppression with the peak EOG shows the accuracy of the EOG as an estimate of intracellular potential in the population of olfactory sensory neurons. In addition, these results have important implications about traffic in olfactory nerve bundles. We did not observe multiple peaks corresponding to stimulated and unstimulated receptor neurons. This suggests synchronization of spikes in olfactory nerve, perhaps by ephaptic interactions. The long-lasting effect on spike latency shows that action potentials continue in the nerve throughout the duration of an odor stimulus in spite of many reports of depolarization block in olfactory receptor neuron cell bodies. Finally, strong odor stimulation caused almost complete block of antidromic spikes. This indicates that a very

  1. Spatiotemporal dynamics of sensory responses in layer 2/3 of rat barrel cortex measured in vivo by voltage-sensitive dye imaging combined with whole-cell voltage recordings and neuron reconstructions.

    PubMed

    Petersen, Carl C H; Grinvald, Amiram; Sakmann, Bert

    2003-02-15

    The spatiotemporal dynamics of the sensory response in layer 2/3 of primary somatosensory cortex evoked by a single brief whisker deflection was investigated by simultaneous voltage-sensitive dye (VSD) imaging and whole-cell (WC) voltage recordings in the anesthetized rat combined with reconstructions of dendritic and axonal arbors of L2/3 pyramids. Single and dual WC recordings from pyramidal cells indicated a strong correlation between the local VSD population response and the simultaneously measured subthreshold postsynaptic potential changes in both amplitude and time course. The earliest VSD response was detected 10-12 msec after whisker deflection centered above the barrel isomorphic to the stimulated principal whisker. It was restricted horizontally to the size of a single barrel-column coextensive with the dendritic arbor of barrel-column-related pyramids in L2/3. The horizontal spread of excitation remained confined to a single barrel-column with weak whisker deflection. With intermediate deflections, excitation spread into adjacent barrel-columns, propagating twofold more rapidly along the rows of the barrel field than across the arcs, consistent with the preferred axonal arborizations in L2/3 of reconstructed pyramidal neurons. Finally, larger whisker deflections evoked excitation spreading over the entire barrel field within approximately 50 msec before subsiding over the next approximately 250 msec. Thus the subthreshold cortical map representing a whisker deflection is dynamic on the millisecond time scale and strongly depends on stimulus strength. The sequential spatiotemporal activation of the excitatory neuronal network in L2/3 by a simple sensory stimulus can thus be accounted for primarily by the columnar restriction of L4 to L2/3 excitatory connections and the axonal field of barrel-related pyramids.

  2. Local opioid-sensitive afferent sensory neurones in the modulation of gastric damage induced by Paf.

    PubMed Central

    Esplugues, J. V.; Whittle, B. J.; Moncada, S.

    1989-01-01

    1. The role of local sensory neurones in modulating the extent of gastric mucosal damage induced by close-arterial infusion of platelet-activating factor (Paf 50 ng kg-1 min-1 for 10 min) has been investigated in the anaesthetized rat. 2. Local intra-arterial infusion of the neurotoxin, tetrodotoxin (TTX), substantially augmented the mucosal damage induced by Paf, as assessed by both macroscopic and histological techniques. 3. In rats pretreated with capsaicin 2 weeks prior to study, to induce a functional ablation of primary afferent neurones, gastric damage induced by Paf was significantly augmented. 4. Administration of morphine (0.75-3 mg kg-1 i.v.) or its peripherally acting quaternary analogue, N-methyl morphine (15 mg kg-1 i.v.), also significantly enhanced the gastric damage induced by Paf. 5. The potentiation by morphine of Paf-induced gastric damage was inhibited by administration of the opioid antagonists, naloxone (1 mg kg-1 i.v.) or the peripherally acting N-methyl nalorphine (3 mg kg-1 i.v.). 6. Administration of TTX or morphine alone, or pretreatment with capsaicin did not induce any detectable mucosal damage, suggesting that interference with local sensory neuronal activity itself does not directly induce mucosal disruption. 7. These results indicate that peripheral opiate-sensitive afferent sensory neurones play a physiological defensive role in the mucosa, attenuating the extent of gastric damage induced by Paf. PMID:2758231

  3. TRESK channel contribution to nociceptive sensory neurons excitability: modulation by nerve injury

    PubMed Central

    2011-01-01

    Background Neuronal hyperexcitability is a crucial phenomenon underlying spontaneous and evoked pain. In invertebrate nociceptors, the S-type leak K+ channel (analogous to TREK-1 in mammals) plays a critical role of in determining neuronal excitability following nerve injury. Few data are available on the role of leak K2P channels after peripheral axotomy in mammals. Results Here we describe that rat sciatic nerve axotomy induces hyperexcitability of L4-L5 DRG sensory neurons and decreases TRESK (K2P18.1) expression, a channel with a major contribution to total leak current in DRGs. While the expression of other channels from the same family did not significantly change, injury markers ATF3 and Cacna2d1 were highly upregulated. Similarly, acute sensory neuron dissociation (in vitro axotomy) produced marked hyperexcitability and similar total background currents compared with neurons injured in vivo. In addition, the sanshool derivative IBA, which blocked TRESK currents in transfected HEK293 cells and DRGs, increased intracellular calcium in 49% of DRG neurons in culture. Most IBA-responding neurons (71%) also responded to the TRPV1 agonist capsaicin, indicating that they were nociceptors. Additional evidence of a biological role of TRESK channels was provided by behavioral evidence of pain (flinching and licking), in vivo electrophysiological evidence of C-nociceptor activation following IBA injection in the rat hindpaw, and increased sensitivity to painful pressure after TRESK knockdown in vivo. Conclusions In summary, our results clearly support an important role of TRESK channels in determining neuronal excitability in specific DRG neurons subpopulations, and show that axonal injury down-regulates TRESK channels, therefore contributing to neuronal hyperexcitability. PMID:21527011

  4. Activation of Six1 Expression in Vertebrate Sensory Neurons

    PubMed Central

    Sato, Shigeru; Yajima, Hiroshi; Furuta, Yasuhide; Ikeda, Keiko; Kawakami, Kiyoshi

    2015-01-01

    SIX1 homeodomain protein is one of the essential key regulators of sensory organ development. Six1-deficient mice lack the olfactory epithelium, vomeronasal organs, cochlea, vestibule and vestibuloacoustic ganglion, and also show poor neural differentiation in the distal part of the cranial ganglia. Simultaneous loss of both Six1 and Six4 leads to additional abnormalities such as small trigeminal ganglion and abnormal dorsal root ganglia (DRG). The aim of this study was to understand the molecular mechanism that controls Six1 expression in sensory organs, particularly in the trigeminal ganglion and DRG. To this end, we focused on the sensory ganglia-specific Six1 enhancer (Six1-8) conserved between chick and mouse. In vivo reporter assays using both animals identified an important core region comprising binding consensus sequences for several transcription factors including nuclear hormone receptors, TCF/LEF, SMAD, POU homeodomain and basic-helix-loop-helix proteins. The results provided information on upstream factors and signals potentially relevant to Six1 regulation in sensory neurons. We also report the establishment of a new transgenic mouse line (mSix1-8-NLSCre) that expresses Cre recombinase under the control of mouse Six1-8. Cre-mediated recombination was detected specifically in ISL1/2-positive sensory neurons of Six1-positive cranial sensory ganglia and DRG. The unique features of the mSix1-8-NLSCre line are the absence of Cre-mediated recombination in SOX10-positive glial cells and central nervous system and ability to induce recombination in a subset of neurons derived from the olfactory placode/epithelium. This mouse model can be potentially used to advance research on sensory development. PMID:26313368

  5. Anti-Hu antibodies activate enteric and sensory neurons

    PubMed Central

    Li, Qin; Michel, Klaus; Annahazi, Anita; Demir, Ihsan E.; Ceyhan, Güralp O.; Zeller, Florian; Komorowski, Lars; Stöcker, Winfried; Beyak, Michael J.; Grundy, David; Farrugia, Gianrico; De Giorgio, Roberto; Schemann, Michael

    2016-01-01

    IgG of type 1 anti-neuronal nuclear antibody (ANNA-1, anti-Hu) specificity is a serological marker of paraneoplastic neurological autoimmunity (including enteric/autonomic) usually related to small-cell lung carcinoma. We show here that IgG isolated from such sera and also affinity-purified anti-HuD label enteric neurons and cause an immediate spike discharge in enteric and visceral sensory neurons. Both labelling and activation of enteric neurons was prevented by preincubation with the HuD antigen. Activation of enteric neurons was inhibited by the nicotinic receptor antagonists hexamethonium and dihydro-β-erythroidine and reduced by the P2X antagonist pyridoxal phosphate-6-azo (benzene-2,4-disulfonic acid (PPADS) but not by the 5-HT3 antagonist tropisetron or the N-type Ca-channel blocker ω-Conotoxin GVIA. Ca++ imaging experiments confirmed activation of enteric neurons but not enteric glia. These findings demonstrate a direct excitatory action of ANNA-1, in particular anti-HuD, on visceral sensory and enteric neurons, which involves nicotinic and P2X receptors. The results provide evidence for a novel link between nerve activation and symptom generation in patients with antibody-mediated gut dysfunction. PMID:27905561

  6. Impact of the Sensory Neurons on Melanoma Growth In Vivo

    PubMed Central

    Tapias, Victor; Watkins, Simon C.; Ma, Yang; Shurin, Michael R.; Shurin, Galina V.

    2016-01-01

    Nerve endings are often identified within solid tumors, but their impact on the tumor growth and progression remains poorly understood. Emerging data suggests that the central nervous system may affect cancer development and spreading via the hypothalamic-pituitary-adrenal axis and autonomous nervous system. However, the role of the afferent sensory neurons in tumor growth is unclear, except some reports on perineural invasion in prostate and pancreatic cancer and cancer-related pain syndrome. Here, we provide the results of primary testing of the concept that the interaction between melanoma cells and sensory neurons may induce the formation of tumor-supporting microenvironment via attraction of immune regulatory cells by the tumor-activated dorsal root ganglion (DRG) neurons. We report that despite DRG cells not directly up-regulating proliferation of melanoma cells in vitro, presence of DRG neurons allows tumors to grow significantly faster in vivo. This effect has been associated with increased production of chemokines by tumor-activated DRG neurons and attraction of myeloid-derived suppressor cells both in vitro and in vivo. These initial proof-of-concept results justify further investigations of the sensory (afferent) nervous system in the context of tumorigenesis and the local protumorigenic immunoenvironment. PMID:27227315

  7. Nocistatin sensitizes TRPA1 channels in peripheral sensory neurons.

    PubMed

    Avenali, Luca; Abate Fulas, Oli; Sondermann, Julia; Narayanan, Pratibha; Gomez-Varela, David; Schmidt, Manuela

    2017-01-02

    The ability of sensory neurons to detect potentially harmful stimuli relies on specialized molecular signal detectors such as transient receptor potential (TRP) A1 ion channels. TRPA1 is critically implicated in vertebrate nociception and different pain states. Furthermore, TRPA1 channels are subject to extensive modulation and regulation - processes which consequently affect nociceptive signaling. Here we show that the neuropeptide Nocistatin sensitizes TRPA1-dependent calcium influx upon application of the TRPA1 agonist mustard oil (MO) in cultured sensory neurons of dorsal root ganglia (DRG). Interestingly, TRPV1-mediated cellular calcium responses are unaffected by Nocistatin. Furthermore, Nocistatin-induced TRPA1-sensitization is likely independent of the Nocistatin binding partner 4-Nitrophenylphosphatase domain and non-neuronal SNAP25-like protein homolog 1 (NIPSNAP1) as assessed by siRNA-mediated knockdown in DRG cultures. In conclusion, we uncovered the sensitization of TRPA1 by Nocistatin, which may represent a novel mechanism how Nocistatin can modulate pain.

  8. Distinct mechanosensitive properties of capsaicin-sensitive and -insensitive sensory neurons.

    PubMed

    Drew, Liam J; Wood, John N; Cesare, Paolo

    2002-06-15

    Mechanical stimulation of the somata of cultured neonatal rat dorsal root ganglia (DRG) neurons evoked inward cationic currents that displayed distinct properties between different subsets of cells. The presumptive nociceptor population, defined by capsaicin sensitivity, showed higher thresholds for the induction of an inward current and lower peak currents than other mechanosensitive neurons. A subset of capsaicin-sensitive IB4-positive sensory neurons was refractory to mechanical stimulation. All mechanically activated currents were blocked by gadolinium (IC50 approximately 8 microm) and ruthenium red (IC50 approximately 3 microm). Disruption of the actin cytoskeleton by acute application of 10 microm cytochalasin B inhibited currents much more effectively in capsaicin-insensitive (61%) than capsaicin-sensitive neurons (20%). Extracellular calcium also attenuated mechanosensitive currents and to a greater degree in capsaicin-insensitive neurons than capsaicin-sensitive neurons. These data demonstrate that the somata of different types of cultured sensory neurons have distinct mechanosensitive phenotypes that retain properties associated with nerve terminal mechanosensors in vivo.

  9. TRPA1-mediated responses in trigeminal sensory neurons: interaction between TRPA1 and TRPV1.

    PubMed

    Salas, Margaux M; Hargreaves, Kenneth M; Akopian, Armen N

    2009-04-01

    The transient receptor potential (TRP)A1 channel is involved in the transduction of inflammation-induced noxious stimuli from the periphery. Previous studies have characterized the properties of TRPA1 in heterologous expression systems. However, there is little information on the properties of TRPA1-mediated currents in sensory neurons. A capsaicin-sensitive subset of rat and mouse trigeminal ganglion sensory neurons was activated with TRPA1-specific agonists, mustard oil and the cannabinoid WIN55,212. Mustard oil- and WIN55,212-gated currents exhibited marked variability in their kinetics of activation and acute desensitization. TRPA1-mediated responses in neurons also possess a characteristic voltage dependency with profound outward rectification that is influenced by extracellular Ca(2+) and the type and concentration of TRPA1-specific agonists. Examination of TRPA1-mediated responses in TRPA1-containing cells indicated that the features of neuronal TRPA1 are not duplicated in cells expressing only TRPA1 and, instead, can be restored only when TRPA1 and TRPV1 channels are coexpressed. In summary, our results suggest that TRPA1-mediated responses in sensory neurons have distinct characteristics that can be accounted for by the coexpression of the TRPV1 and TRPA1 channels.

  10. Inflammation of peripheral tissues and injury to peripheral nerves induce differing effects in the expression of the calcium-sensitive N-arachydonoylethanolamine-synthesizing enzyme and related molecules in rat primary sensory neurons.

    PubMed

    Sousa-Valente, João; Varga, Angelika; Torres-Perez, Jose Vicente; Jenes, Agnes; Wahba, John; Mackie, Ken; Cravatt, Benjamin; Ueda, Natsuo; Tsuboi, Kazuhito; Santha, Peter; Jancso, Gabor; Tailor, Hiren; Avelino, António; Nagy, Istvan

    2017-06-01

    Elevation of intracellular Ca(2+) concentration induces the synthesis of N-arachydonoylethanolamine (anandamide) in a subpopulation of primary sensory neurons. N-acylphosphatidylethanolamine phospholipase D (NAPE-PLD) is the only known enzyme that synthesizes anandamide in a Ca(2+) -dependent manner. NAPE-PLD mRNA as well as anandamide's main targets, the excitatory transient receptor potential vanilloid type 1 ion channel (TRPV1), the inhibitory cannabinoid type 1 (CB1) receptor, and the main anandamide-hydrolyzing enzyme fatty acid amide hydrolase (FAAH), are all expressed by subpopulations of nociceptive primary sensory neurons. Thus, NAPE-PLD, TRPV1, the CB1 receptor, and FAAH could form an autocrine signaling system that could shape the activity of a major subpopulation of nociceptive primary sensory neurons, contributing to the development of pain. Although the expression patterns of TRPV1, the CB1 receptor, and FAAH have been comprehensively elucidated, little is known about NAPE-PLD expression in primary sensory neurons under physiological and pathological conditions. This study shows that NAPE-PLD is expressed by about one-third of primary sensory neurons, the overwhelming majority of which also express nociceptive markers as well as the CB1 receptor, TRPV1, and FAAH. Inflammation of peripheral tissues and injury to peripheral nerves induce differing but concerted changes in the expression pattern of NAPE-PLD, the CB1 receptor, TRPV1, and FAAH. Together these data indicate the existence of the anatomical basis for an autocrine signaling system in a major proportion of nociceptive primary sensory neurons and that alterations in that autocrine signaling by peripheral pathologies could contribute to the development of both inflammatory and neuropathic pain.

  11. [Changes in the expression of large-conductance calcium-activated potassium channels in dorsal root ganglion neurons after electrical injury in rats' sciatic nerves and its influence on sensory conduction function].

    PubMed

    Wang, Guangning; Li, Xueyong; Xu, Xiaoli; Ren, Pan

    2016-06-01

    To study the changes in the expression of large-conductance calcium-activated potassium (BKCa) channels in dorsal root ganglion (DRG) neurons after electrical injury in rats' sciatic nerves and its influence on sensory conduction function. One-hundred and thirty-six adult SD rats were divided into normal control group, sham electrical injury group, and 75, 100, 125 V electrical injury groups according to the random number table, with 8 rats in normal control group and 32 rats in each of the rest 4 groups. Rats in normal control group were routinely fed without any treatment. Blunt dissection of the sciatic nerves of left hind leg of rats was performed in sham electrical injury group, while sciatic nerves of left hind leg of rats in electrical injury groups were electrically injured with corresponding voltage. Eight rats of normal control group fed for one week, and 8 rats from each of the rest four groups on post injury day (PID) 3 and in post injury week (PIW) 1, 2, 3 respectively were collected to detect the paw withdrawal mechanical threshold (PWMT). In addition, rats of 100 V electrical injury group in PIW 1 were collected and intrathecally injected with NS1619 after former PWMT detection, and PWMT was detected per 30 minutes within three hours post injection. The rats in each group at each time point were sacrificed after PWMT detection. The DRG of L4 to L6 segments of spinal cord was sampled to observe the BKCa channels distribution with immunohistochemical staining and to detect the protein and mRNA expressions of BKCa channels with Western blotting and reverse transcription-polymerase chain reaction respectively. Data were processed with one-way analysis of variance, analysis of variance of factorial design, and SNK test. (1) The PWMT values of rats in 75 and 100 V electrical injury groups on PID 3 and in PIW 1, 2, 3 were (5.8±0.6), (5.0±0.8), (4.2±0.3), (5.9±1.1) g; (5.3±1.3), (5.9±2.0), (4.5±2.7), (4.3±1.3) g, respectively, which were

  12. Receptive properties of embryonic chick sensory neurons innervating skin.

    PubMed

    Koltzenburg, M; Lewin, G R

    1997-11-01

    Receptive properties of embryonic chick sensory neurons innervating skin. J. Neurophysiol. 78: 2560-2568, 1997. We describe a new in vitro skin-nerve preparation from chick embryos that allows detailed study of the functional properties of developing sensory neurons innervating skin. Functionally single sensory afferents were isolated by recording from their axons in microdissected filaments of the cutaneous femoralis medialis nerve, which innervates skin of the thigh. A total of 157 single neurons were characterized from embryos [embryonic days 17-21 (E17-E21), n = 115] and hatchlings up to 3 wk old (n = 42). Neurons were initially classified on the basis of their conduction velocity; those conducting below 1.0 m/s were being classified as C fibers and faster conducting fibers as A fibers. The proportions of A and C fibers encountered in embryonic and hatchling preparations were not very different, indicating that myelination and axon growth proceeds quite slowly over the period studied. Afferent fibers that could subserve nociceptive and nonnociceptive functions were identified in the time period studied. Subpopulations of low-threshold myelinated afferent units exhibited rapidly or slowly adapting discharges to constant force stimuli and could have tactile functions. Many afferent fibers responded to noxious heat and were excited and sensitized by exposure to inflammatory mediators, suggesting that they are nociceptors. The behavior of these units changed in several respects over the period studied. The discharge of C fibers to noxious heat increased with age as did their mechanical thresholds. A substantial population of heat-responsive neurons (34% of the A fibers) present in embryos were not encountered in hatchling chicks. This indicates that substantial changes in the physiological response properties of sensory afferents occur after hatching. We conclude that this new preparation can be used for quantitative assessment of the receptive properties of

  13. Sensory innervation of rat contracture shoulder model.

    PubMed

    Ochiai, Nobuyasu; Ohtori, Seiji; Kenmoku, Tomonori; Yamazaki, Hironori; Ochiai, Satoko; Saisu, Takashi; Matsuki, Keisuke; Takahashi, Kazuhisa

    2013-02-01

    To date, few studies have investigated the cause of pain experienced by patients with frozen shoulder. The purposes of this study were to establish a rat contracture model and clarify the innervation pattern of the glenohumeral (GH) joint and subacromial bursa (SAB) using immunohistochemistry in the dorsal root ganglion (DRG) neurons. The rat contracture models were made by tying the animal's humerus and scapula with No. 2-0 FiberWire (Arthrex, Naples, FL, USA). Contracture was confirmed on x-ray images taken 8 weeks after the operation. Subsequently, two kinds of neurotracers, Fluoro-Gold (FG) (Fluorochrome, Denver, CO, USA) and 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate (DiI) (Molecular Probes, Eugene, OR, USA), were used to detect the GH joints and SAB separately. FG tracers were injected into GH joints, and DiI tracers were injected into the SAB. At 7 days after injection, DRGs were harvested between C1 and T1. Immunohistochemistry by use of calcitonin gene-related peptide (CGRP) was performed. CGRP is thought to be one of the causes of pain sensation in joint disease. We evaluated the percentages of FG-labeled CGRP-immunoreactive (CGRP-ir) neurons in the total number of FG-labeled neurons and of DiI-labeled CGRP-ir neurons in the total number of DiI-labeled neurons. Abduction and total arc of the rotation were statistically significantly decreased in the contracture group. Furthermore, the percentage of CGRP-ir DRG neurons was significantly higher in the contracture group in both the GH joint and SAB. These results show that pain sensation in rat shoulder contracture may be induced by the up-regulation of CGRP expression in DRG neurons. Copyright © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

  14. Serotonin-immunoreactive sensory neurons in the antenna of the cockroach Periplaneta americana.

    PubMed

    Watanabe, Hidehiro; Shimohigashi, Miki; Yokohari, Fumio

    2014-02-01

    The antennae of insects contain a vast array of sensory neurons that process olfactory, gustatory, mechanosensory, hygrosensory, and thermosensory information. Except those with multimodal functions, most sensory neurons use acetylcholine as a neurotransmitter. Using immunohistochemistry combined with retrograde staining of antennal sensory neurons in the cockroach Periplaneta americana, we found serotonin-immunoreactive sensory neurons in the antenna. These were selectively distributed in chaetic and scolopidial sensilla and in the scape, the pedicel, and first 15 segments of the flagellum. In a chaetic sensillum, A single serotonin-immunoreactive sensory neuron cohabited with up to four serotonin-negative sensory neurons. Based on their morphological features, serotonin-immunopositive and -negative sensory neurons might process mechanosensory and contact chemosensory modalities, respectively. Scolopidial sensilla constitute the chordotonal and Johnston's organs within the pedicel and process antennal vibrations. Immunoelectron microscopy clearly revealed that serotonin-immunoreactivities selectively localize to a specific type of mechanosensory neuron, called type 1 sensory neuron. In a chordotonal scolopidial sensillum, a serotonin-immunoreactive type 1 neuron always paired with a serotonin-negative type 1 neuron. Conversely, serotonin-immunopositive and -negative type 1 neurons were randomly distributed in Johnston's organ. In the deutocerebrum, serotonin-immunoreactive sensory neuron axons formed three different sensory tracts and those from distinct types of sensilla terminated in distinct brain regions. Our findings indicate that a biogenic amine, serotonin, may act as a neurotransmitter in peripheral mechanosensory neurons.

  15. Cannabinoid receptor antagonists AM251 and AM630 activate TRPA1 in sensory neurons

    PubMed Central

    Patil, Mayur; Patwardhan, Amol; Salas, Margaux M.; Hargreaves, Kenneth M.; Akopian, Armen N.

    2011-01-01

    Cannabinoid receptor antagonists have been utilized extensively in vivo as well as in vitro, but their selectivity has not been fully examined. We investigated activation of sensory neurons by two cannabinoid antagonists – AM251 and AM630. AM251 and AM630 activated trigeminal (TG) sensory neurons in a concentration-dependent fashion (threshold 1 μM). AM251 and AM630 responses are mediated by the TRPA1 channel in a majority (90–95%) of small-to-medium TG sensory neurons. AM630 (1–100 μM), but not AM251, was a significantly more potent agonist in cells co-expressing both TRPA1 and TRPV1 channels. We next evaluated AM630 and AM251 effects on TRPV1- and TRPA1-mediated responses in TG neurons. Capsaicin (CAP) effects were inhibited by pre-treatment with AM630, but not AM251. Mustard oil (MO) and WIN55,212-2 (WIN) TRPA1 mediated responses were also inhibited by pre-treatment with AM630, but not AM251 (25uM each). Co-treatment of neurons with WIN and either AM630 or AM251 had opposite effects: AM630 sensitized WIN responses, whereas AM251 inhibited WIN responses. WIN-induced inhibition of CAP responses in sensory neurons was reversed by AM630 pre-treatment and AM251 co-treatment (25μM each), as these conditions inhibit WIN responses. Hindpaw injections of AM630 and AM251 did not produce nocifensive behaviors. However, both compounds modulated CAP-induced thermal hyperalgesia in wild-type mice and rats, but not TRPA1 null-mutant mice. AMs also partially regulate WIN inhibition of CAP-induced thermal hyperalgesia in a TRPA1-dependent fashion. In summary, these findings demonstrate alternative targets for the cannabinoid antagonists, AM251 and AM630, in peripheral antihyperalgesia which involve certain TRP channels. PMID:21645531

  16. Cannabinoid receptor antagonists AM251 and AM630 activate TRPA1 in sensory neurons.

    PubMed

    Patil, Mayur; Patwardhan, Amol; Salas, Margaux M; Hargreaves, Kenneth M; Akopian, Armen N

    2011-09-01

    Cannabinoid receptor antagonists have been utilized extensively in vivo as well as in vitro, but their selectivity has not been fully examined. We investigated activation of sensory neurons by two cannabinoid antagonists - AM251 and AM630. AM251 and AM630 activated trigeminal (TG) sensory neurons in a concentration-dependent fashion (threshold 1 μM). AM251 and AM630 responses are mediated by the TRPA1 channel in a majority (90-95%) of small-to-medium TG sensory neurons. AM630 (1-100 μM), but not AM251, was a significantly more potent agonist in cells co-expressing both TRPA1 and TRPV1 channels. We next evaluated AM630 and AM251 effects on TRPV1- and TRPA1-mediated responses in TG neurons. Capsaicin (CAP) effects were inhibited by pre-treatment with AM630, but not AM251. Mustard oil (MO) and WIN55,212-2 (WIN) TRPA1 mediated responses were also inhibited by pre-treatment with AM630, but not AM251 (25 uM each). Co-treatment of neurons with WIN and either AM630 or AM251 had opposite effects: AM630 sensitized WIN responses, whereas AM251 inhibited WIN responses. WIN-induced inhibition of CAP responses in sensory neurons was reversed by AM630 pre-treatment and AM251 co-treatment (25 μM each), as these conditions inhibit WIN responses. Hindpaw injections of AM630 and AM251 did not produce nocifensive behaviors. However, both compounds modulated CAP-induced thermal hyperalgesia in wild-type mice and rats, but not TRPA1 null-mutant mice. AMs also partially regulate WIN inhibition of CAP-induced thermal hyperalgesia in a TRPA1-dependent fashion. In summary, these findings demonstrate alternative targets for the cannabinoid antagonists, AM251 and AM630, in peripheral antihyperalgesia which involve certain TRP channels.

  17. Isolation, Purification, and Culture of Primary Murine Sensory Neurons

    PubMed Central

    Katzenell, Sarah; Cabrera, Jorge R.; North, Brian J.; Leib, David A.

    2017-01-01

    Cultured primary neurons have been of extraordinary value for the study of neuronal anatomy, cell biology, and physiology. While use of neuronal cell lines has ease and utility, there are often caveats that arise due to their mitotic nature. This methods article presents detailed methodology for the preparation, purification, and culture of adult murine sensory neurons for the study of herpes simplex virus lytic and latent infections. While virology is the application for our laboratory, these cultures also have broad utility for neurobiologists and cell biologists. While these primary cultures have been highly informative, the methodology is challenging to many investigators. Through publication of this highly detailed protocol, it is our hope that the use of this culture system can spread in the field to allow more rapid progress in furthering our understanding of neurotropic virus infection. PMID:28808974

  18. Basing perceptual decisions on the most informative sensory neurons.

    PubMed

    Scolari, Miranda; Serences, John T

    2010-10-01

    Single unit recording studies show that perceptual decisions are often based on the output of sensory neurons that are maximally responsive (or "tuned") to relevant stimulus features. However, when performing a difficult discrimination between two highly similar stimuli, perceptual decisions should instead be based on the activity of neurons tuned away from the relevant feature (off-channel neurons) as these neurons undergo a larger firing rate change and are thus more informative. To test this hypothesis, we measured feature-selective responses in human primary visual cortex (V1) using functional magnetic resonance imaging and show that the degree of off-channel activation predicts performance on a difficult visual discrimination task. Moreover, this predictive relationship between off-channel activation and perceptual acuity is not simply the result of extensive practice with a specific stimulus feature (as in studies of perceptual learning). Instead, relying on the output of the most informative sensory neurons may represent a general, and optimal, strategy for efficiently computing perceptual decisions.

  19. Sensory deprivation disrupts homeostatic regeneration of newly generated olfactory sensory neurons after injury in adult mice.

    PubMed

    Kikuta, Shu; Sakamoto, Takashi; Nagayama, Shin; Kanaya, Kaori; Kinoshita, Makoto; Kondo, Kenji; Tsunoda, Koichi; Mori, Kensaku; Yamasoba, Tatsuya

    2015-02-11

    Although it is well known that injury induces the generation of a substantial number of new olfactory sensory neurons (OSNs) in the adult olfactory epithelium (OE), it is not well understood whether olfactory sensory input influences the survival and maturation of these injury-induced OSNs in adults. Here, we investigated whether olfactory sensory deprivation affected the dynamic incorporation of newly generated OSNs 3, 7, 14, and 28 d after injury in adult mice. Mice were unilaterally deprived of olfactory sensory input by inserting a silicone tube into their nostrils. Methimazole, an olfactotoxic drug, was also injected intraperitoneally to bilaterally ablate OSNs. The OE was restored to its preinjury condition with new OSNs by day 28. No significant differences in the numbers of olfactory marker protein-positive mature OSNs or apoptotic OSNs were observed between the deprived and nondeprived sides 0-7 d after injury. However, between days 7 and 28, the sensory-deprived side showed markedly fewer OSNs and mature OSNs, but more apoptotic OSNs, than the nondeprived side. Intrinsic functional imaging of the dorsal surface of the olfactory bulb at day 28 revealed that responses to odor stimulation were weaker in the deprived side compared with those in the nondeprived side. Furthermore, prevention of cell death in new neurons 7-14 d after injury promoted the recovery of the OE. These results indicate that, in the adult OE, sensory deprivation disrupts compensatory OSN regeneration after injury and that newly generated OSNs have a critical time window for sensory-input-dependent survival 7-14 d after injury.

  20. Switch of rhodopsin expression in terminally differentiated Drosophila sensory neurons.

    PubMed

    Sprecher, Simon G; Desplan, Claude

    2008-07-24

    Specificity of sensory neurons requires restricted expression of one sensory receptor gene and the exclusion of all others within a given cell. In the Drosophila retina, functional identity of photoreceptors depends on light-sensitive Rhodopsins (Rhs). The much simpler larval eye (Bolwig organ) is composed of about 12 photoreceptors, eight of which are green-sensitive (Rh6) and four blue-sensitive (Rh5). The larval eye becomes the adult extraretinal 'eyelet' composed of four green-sensitive (Rh6) photoreceptors. Here we show that, during metamorphosis, all Rh6 photoreceptors die, whereas the Rh5 photoreceptors switch fate by turning off Rh5 and then turning on Rh6 expression. This switch occurs without apparent changes in the programme of transcription factors that specify larval photoreceptor subtypes. We also show that the transcription factor Senseless (Sens) mediates the very different cellular behaviours of Rh5 and Rh6 photoreceptors. Sens is restricted to Rh5 photoreceptors and must be excluded from Rh6 photoreceptors to allow them to die at metamorphosis. Finally, we show that Ecdysone receptor (EcR) functions autonomously both for the death of larval Rh6 photoreceptors and for the sensory switch of Rh5 photoreceptors to express Rh6. This fate switch of functioning, terminally differentiated neurons provides a novel, unexpected example of hard-wired sensory plasticity.

  1. Early bilateral sensory deprivation blocks the development of coincident discharge in rat barrel cortex.

    PubMed

    Ghoshal, Ayan; Pouget, Pierre; Popescu, Maria; Ebner, Ford

    2009-02-25

    Several theories have proposed a functional role for synchronous neuronal firing in generating the neural code of a sensory perception. Synchronous neural activity develops during a critical postnatal period of cortical maturation, and severely reducing neural activity in a sensory pathway during this period could interfere with the development of coincident discharge among cortical neurons. Loss of such synchrony could provide a fundamental mechanism for the degradation of acuity shown in behavioral studies. We tested the hypothesis that synchronous discharge of barrel cortex neurons would fail to develop after sensory deprivation produced by bilateral whisker trimming from birth to postnatal day 60. By studying the correlated discharge of cortical neuron pairs, we found evidence for strong correlated firing in control animals, and this synchrony was almost absent among pairs of cortical barrel neurons in deprived animals. The degree of synchrony impairment was different in subregions of rat barrel cortex. The model that best fits the data is that cortical neurons receiving direct inputs from the primary sensory (lemniscal) pathway show the greatest decrement in synchrony following sensory deprivation, while neurons with diverse inputs from other areas of thalamus and cortex are relatively less affected in this dimension of cortical function.

  2. Tiling of the Drosophila epidermis by multidendritic sensory neurons.

    PubMed

    Grueber, Wesley B; Jan, Lily Y; Jan, Yuh Nung

    2002-06-01

    Insect dendritic arborization (da) neurons provide an opportunity to examine how diverse dendrite morphologies and dendritic territories are established during development. We have examined the morphologies of Drosophila da neurons by using the MARCM (mosaic analysis with a repressible cell marker) system. We show that each of the 15 neurons per abdominal hemisegment spread dendrites to characteristic regions of the epidermis. We place these neurons into four distinct morphological classes distinguished primarily by their dendrite branching complexities. Some class assignments correlate with known proneural gene requirements as well as with central axonal projections. Our data indicate that cells within two morphological classes partition the body wall into distinct, non-overlapping territorial domains and thus are organized as separate tiled sensory systems. The dendritic domains of cells in different classes, by contrast, can overlap extensively. We have examined the cell-autonomous roles of starry night (stan) (also known as flamingo (fmi)) and sequoia (seq) in tiling. Neurons with these genes mutated generally terminate their dendritic fields at normal locations at the lateral margin and segment border, where they meet or approach the like dendrites of adjacent neurons. However, stan mutant neurons occasionally send sparsely branched processes beyond these territories that could potentially mix with adjacent like dendrites. Together, our data suggest that widespread tiling of the larval body wall involves interactions between growing dendritic processes and as yet unidentified signals that allow avoidance by like dendrites.

  3. Bacteria activate sensory neurons that modulate pain and inflammation

    PubMed Central

    Chiu, Isaac M.; Heesters, Balthasar A.; Ghasemlou, Nader; Von Hehn, Christian A.; Zhao, Fan; Tran, Johnathan; Wainger, Brian; Strominger, Amanda; Muralidharan, Sriya; Horswill, Alexander R.; Wardenburg, Juliane Bubeck; Hwang, Sun Wook; Carroll, Michael C.; Woolf, Clifford J.

    2013-01-01

    Summary Nociceptor sensory neurons are specialized to detect potentially damaging stimuli, protecting the organism by initiating the sensation of pain and eliciting defensive behaviors. Bacterial infections produce pain by unknown molecular mechanisms, although they are presumed secondary to immune activation. Here we demonstrate that bacteria directly activate nociceptors, and that the immune response mediated through TLR2, MyD88, T cells, B cells, and neutrophils/monocytes is not necessary for Staphylococcus aureus induced pain in mice. Mechanical and thermal hyperalgesia parallels live bacterial load rather than tissue swelling or immune activation. Bacteria induce calcium flux and action potentials in nociceptor neurons, in part via bacterial N-formylated peptides and the pore-forming toxin alpha-hemolysin through distinct mechanisms. Specific ablation of Nav1.8-lineage neurons, which include nociceptors, abrogated pain during bacterial infection, but concurrently increased local immune infiltration and lymphadenopathy of the draining lymph node. Thus, bacterial pathogens produce pain by directly activating sensory neurons that modulate inflammation, an unsuspected role for the nervous system in host-pathogen interactions. PMID:23965627

  4. Making sense of the sensory regulation of hunger neurons.

    PubMed

    Chen, Yiming; Knight, Zachary A

    2016-04-01

    AgRP and POMC neurons are two key cell types that regulate feeding in response to hormones and nutrients. Recently, it was discovered that these neurons are also rapidly modulated by the mere sight and smell of food. This rapid sensory regulation "resets" the activity of AgRP and POMC neurons before a single bite of food has been consumed. This surprising and counterintuitive discovery challenges longstanding assumptions about the function and regulation of these cells. Here we review these recent findings and discuss their implications for our understanding of feeding behavior. We propose several alternative hypotheses for how these new observations might be integrated into a revised model of the feeding circuit, and also highlight some of the key questions that remain to be answered.

  5. Making sense of the sensory regulation of hunger neurons

    PubMed Central

    Chen, Yiming; Knight, Zachary A.

    2016-01-01

    AgRP and POMC neurons are two key cell types that regulate feeding in response to hormones and nutrients. Recently, it was discovered that these neurons are also rapidly modulated by the mere sight and smell of food. This rapid sensory regulation “resets” the activity of AgRP and POMC neurons before a single bite of food has been consumed. This surprising and counterintuitive discovery challenges longstanding assumptions about the function and regulation of these cells. Here we review these recent findings and discuss their implications for our understanding of feeding behavior. We propose several alternative hypotheses for how these new observations might be integrated into a revised model of the feeding circuit, and also highlight some of the key questions that remain to be answered. PMID:26898524

  6. Identification of motor neurons and a mechanosensitive sensory neuron in the defecation circuitry of Drosophila larvae.

    PubMed

    Zhang, Wei; Yan, Zhiqiang; Li, Bingxue; Jan, Lily Yeh; Jan, Yuh Nung

    2014-10-30

    Defecation allows the body to eliminate waste, an essential step in food processing for animal survival. In contrast to the extensive studies of feeding, its obligate counterpart, defecation, has received much less attention until recently. In this study, we report our characterizations of the defecation behavior of Drosophila larvae and its neural basis. Drosophila larvae display defecation cycles of stereotypic frequency, involving sequential contraction of hindgut and anal sphincter. The defecation behavior requires two groups of motor neurons that innervate hindgut and anal sphincter, respectively, and can excite gut muscles directly. These two groups of motor neurons fire sequentially with the same periodicity as the defecation behavior, as revealed by in vivo Ca(2+) imaging. Moreover, we identified a single mechanosensitive sensory neuron that innervates the anal slit and senses the opening of the intestine terminus. This anus sensory neuron relies on the TRP channel NOMPC but not on INACTIVE, NANCHUNG, or PIEZO for mechanotransduction.

  7. Statins decrease expression of the proinflammatory neuropeptides calcitonin gene-related peptide and substance P in sensory neurons.

    PubMed

    Bucelli, Robert C; Gonsiorek, Eugene A; Kim, Woo-Yang; Bruun, Donald; Rabin, Richard A; Higgins, Dennis; Lein, Pamela J

    2008-03-01

    Clinical and experimental observations suggest that statins may be useful for treating diseases presenting with predominant neurogenic inflammation, but the mechanism(s) mediating this potential therapeutic effect are poorly understood. In this study, we tested the hypothesis that statins act directly on sensory neurons to decrease expression of proinflammatory neuropeptides that trigger neurogenic inflammation, specifically calcitonin gene-related peptide (CGRP) and substance P. Reverse transcriptase-polymerase chain reaction, radioimmunoassay, and immunocytochemistry were used to quantify CGRP and substance P expression in dorsal root ganglia (DRG) harvested from adult male rats and in primary cultures of sensory neurons derived from embryonic rat DRG. Systemic administration of statins at pharmacologically relevant doses significantly reduced CGRP and substance P levels in DRG in vivo. In cultured sensory neurons, statins blocked bone morphogenetic protein (BMP)-induced CGRP and substance P expression and decreased expression of these neuropeptides in sensory neurons pretreated with BMPs. These effects were concentration-dependent and occurred independent of effects on cell survival or axon growth. Statin inhibition of neuropeptide expression was reversed by supplementation with mevalonate and cholesterol, but not isoprenoid precursors. BMPs signal via Smad activation, and cholesterol depletion by statins inhibited Smad1 phosphorylation and nuclear translocation. These findings identify a novel action of statins involving down-regulation of proinflammatory neuropeptide expression in sensory ganglia via cholesterol depletion and decreased Smad1 activation and suggest that statins may be effective in attenuating neurogenic inflammation.

  8. The influence of alpha1-adrenoreceptors on neuropeptide release from primary sensory neurons of the lower urinary tract.

    PubMed

    Trevisani, Marcello; Campi, Barbara; Gatti, Raffaele; André, Eunice; Materazzi, Serena; Nicoletti, Paola; Gazzieri, David; Geppetti, Pierangelo

    2007-09-01

    Adrenergic alpha(1)-receptors agonists and antagonists have been reported to increase and reduce, respectively, neurogenic inflammatory responses mediated by capsaicin-sensitive sensory neurons. However, the precise role and localization of the alpha(1)-adrenoceptors involved in these effects are not known. We have studied in the rat whether functional alpha(1)-adrenoreceptors are expressed in primary sensory neurons, and whether they regulate neurogenic inflammation and nociceptive responses in the urinary bladder. The alpha(1)-adrenoreceptor agonist phenylephrine (1 micromol/l) (1) mobilized intracellular Ca(2+) in cultured lumbar and sacral dorsal root ganglia neurons, (2) caused the release of substance P (SP) from terminals of capsaicin-sensitive sensory neurons from the lumbar enlargement of the dorsal spinal cord and urinary bladder, and (3) increased plasma protein extravasation in the urinary bladder. All these effects were abolished by the alpha(1)-adrenoceptor antagonist alfuzosin (10 micromol/l). Furthermore, alfuzosin (30 microg/kg, i.v.) partially, but significantly, inhibited cyclophosphamide-induced plasma protein extravasation in the rat urinary bladder. Phenylephrine-induced Ca(2+) mobilization in cultured dorsal root ganglia neurons was exaggerated by pretreating the rats in vivo with cyclophosphamide. Finally, cyclophosphamide increased c-fos expression in the rat lumbar spinal cord. Also these in vitro and in vivo effects were inhibited by pretreatment with alfuzosin. Alpha(1)-adrenoceptors are functionally expressed by capsaicin-sensitive, nociceptive, primary sensory neurons of the rat urinary tract, and their activation may contribute to signal irritative and nociceptive responses arising from the urinary tract. It is possible that, at least, part of the beneficial effects of alpha(1)-adrenoceptor antagonists in the amelioration of storage symptoms in the lower urinary tract derives from their inhibitory effect on neurogenic inflammatory

  9. Evidence for orthogonal arrays of particles in the plasma membranes of olfactory and vomeronasal sensory neurons of vertebrates.

    PubMed

    Miragall, F

    1983-08-01

    Plasma membranes of sensory neurons from the olfactory and vomeronasal neuroepithelia of the male rat and olfactory neuroepithelium of the tiger salamander (Ambystoma tigrinum) have been examined, using the freeze-fracture technique, for the presence and morphology of orthogonal arrays of particles (OAP). Numerous OAP were scattered on the P-face of plasma membranes of the dendrites and cell bodies from rat vomeronasal sensory neurons. The OAP were 720 +/- 200 nm2 in area and they consisted of 4 to 20 particles whose centre-to-centre distance was about 7 nm. On the E-face, complementary orthogonal arrays of pits were observed. No OAP were detected in the olfactory sensory neurons of the rat. In the dendritic and perikaryal plasma membranes of the tiger salamander olfactory sensory neurons, OAP 2230 +/- 970 nm2 in area were observed on the P-face. The OAP consisted of 12 to 36 particles. The centre-to-centre distance of the particles was about 7 nm. In the olfactory receptor cell plasma membranes of this species, OAP formed complexes of 2 to 28 individual OAP, the longitudinal axes of which were usually arranged in parallel. Complementary complexes of orthogonal arrays of pits were observed on the E-face.

  10. Epibranchial placode-derived neurons produce BDNF required for early sensory neuron development.

    PubMed

    Harlow, Danielle E; Yang, Hui; Williams, Trevor; Barlow, Linda A

    2011-02-01

    In mice, BDNF provided by the developing taste epithelium is required for gustatory neuron survival following target innervation. However, we find that expression of BDNF, as detected by BDNF-driven β-galactosidase, begins in the cranial ganglia before its expression in the central (hindbrain) or peripheral (taste papillae) targets of these sensory neurons, and before gustatory ganglion cells innervate either target. To test early BDNF function, we examined the ganglia of bdnf null mice before target innervation, and found that while initial neuron survival is unaltered, early neuron development is disrupted. In addition, fate mapping analysis in mice demonstrates that murine cranial ganglia arise from two embryonic populations, i.e., epibranchial placodes and neural crest, as has been described for these ganglia in non-mammalian vertebrates. Only placodal neurons produce BDNF, however, which indicates that prior to innervation, early ganglionic BDNF produced by placode-derived cells promotes gustatory neuron development.

  11. Adaptation to sensory stimulation in the Rat Barrel Cortex

    NASA Astrophysics Data System (ADS)

    Heiss, Jaime

    Sustained stimulation of sensory organs results in adaptation of the neuronal response along the sensory pathway. Whether or not cortical adaptation affects equally excitatory and inhibitory inputs is poorly understood. This question was examined using patch recordings of neurons in the barrel cortex of anesthetized rats while repetitively stimulating the principal whisker. After characterizing the excitation and inhibition evoked either by single or double whisker deflection or by different stimulation strengths, it was found that inhibition, unlike excitation, sums linearly and adapts more, causing the balance between these inputs to shift towards excitation. A comparison of the latency of thalamic firing and evoked synaptic inputs in the cortex strongly suggests that adaptation of inhibition results mostly from depression of inhibitory synapses rather than reduction in the firing of inhibitory cells. A similar change in the balance was reproduced by a simple feedforward model. The differential adaptation of the synaptic inputs that shifts the balance toward excitation may act as a gain mechanism which enhances the subthreshold response during sustained stimulation, despite a reduction in excitation. Natural sensory stimulation rarely arrives in an isolated manner, but in a context of several stimulations, like when a rat sweeps its whisker along a surface with a given texture. It was shown that individual single cells sporadically fail to respond, in a very variable fashion from trial to trial. Whether or not adaptation is correlated among neighboring neurons or is it a private, independent phenomenon was investigated by performing simultaneous recordings. Neighboring neurons presented a highly correlated responsiveness to repetitive stimulation, which strongly varied from trial to trial in a synchronized way. Population averages of a single trial obtained by LFP recordings and VSD imaging differed considerably from the time average but was highly correlated to

  12. Myelinated skin sensory neurons project extensively throughout adult mouse substantia gelatinosa.

    PubMed

    Boada, M Danilo; Woodbury, C Jeffery

    2008-02-27

    The substantia gelatinosa (SG) of the dorsal horn of the spinal cord is a recipient zone for unmyelinated sensory neurons in adults. Recent studies of the central anatomy of physiologically identified skin sensory neurons in neonatal mice have shown that this region also receives substantial inputs from a variety of myelinated afferents. The present experiments were performed to determine whether these neonatal inputs represent a transient phenotype that retracts from the SG. Studies were conducted in an in vivo spinal cord preparation from adult mice; thoracic levels were targeted to facilitate comparisons with previous in vitro findings. We show that the SG continues to receive substantial projections from myelinated skin sensory neurons throughout life. A large population of myelinated nociceptors conducting in the upper A delta and low A beta range maintained extensive projections throughout all areas of the SG well into adulthood; the latter gave rise to dorsally recurving "flame"-shaped arbors extending into the marginal layer that were identical to afferents described in neonates and after nerve injury in adult rats. Furthermore, exquisitely sensitive down hair follicle afferents projected throughout the inner half of the SG (i.e., lamina IIi) and sent dense clusters of terminals well into the outer SG (IIo), where they intermingled with those of unmyelinated nociceptors. Arguments are presented that the SG likely plays a predominant role in tactile processing under normal conditions, but that this role switches rapidly to nociceptive-only during environmental exigencies imposed by temperature extremes.

  13. Olfactory sensory neurons are trophically dependent on the olfactory bulb for their prolonged survival.

    PubMed

    Schwob, J E; Szumowski, K E; Stasky, A A

    1992-10-01

    In most neural systems, developing neurons are trophically dependent on contact with their synaptic target for their survival and for some features of their differentiation. However, in the olfactory system, it is unclear whether or not the survival and differentiation of olfactory sensory neurons depend on contact with the olfactory bulb (normally the sole synaptic target for these neurons). In order to address this issue, we examined neuronal life-span and differentiation in adult rats subjected to unilateral olfactory bulb ablation at least 1 month prior to use. Life-span of a newly generated cohort of olfactory neurons was determined by labeling them at their "birth" via the incorporation of 3H-thymidine. In the absence of the bulb, neurons are continually produced at a twofold greater rate. However, the epithelium on the ablated side is thinner, indicating that average neuronal life-span must be reduced in the targetless epithelium. Indeed, nearly 90% of the labeled neurons disappear from the bulbectomized side between 5 d and 2 weeks of neuronal age. Moreover, on electron microscopic examination, olfactory axons are degenerating in large numbers on the ablated side. Since labeled neurons migrate apically through the width of the epithelium during this same period, it appears that most, if not all, neurons on the ablated side have a life-span on the order of 2 weeks or less. In contrast, there is a more moderate degree of neuronal loss on the unoperated side of the same animals during the first 2 weeks after tracer injection, and that occurs while the neurons are concentrated in the deeper half of the epithelium, suggesting that there is a preexisting population of neurons in the control epithelium that does not die during this period. Likewise, degenerating axons are much less frequent on the unoperated side. We conclude that life-span is significantly shorter for olfactory neurons born in the targetless epithelium and that olfactory neurons are trophically

  14. Cholinergic neurons in the mouse rostral ventrolateral medulla target sensory afferent areas

    PubMed Central

    Stornetta, Ruth L.; Macon, Conrad J.; Nguyen, Thanh M.; Coates, Melissa B.; Guyenet, Patrice G.

    2012-01-01

    The rostral ventrolateral medulla (RVLM) primarily regulates respiration and the autonomic nervous system. Its medial portion (mRVLM) contains many choline acetyltransferase (ChAT)-immunoreactive (ir) neurons of unknown function. We sought to clarify the role of these cholinergic cells by tracing their axonal projections. We first established that these neurons are neither parasympathetic preganglionic neurons nor motor neurons because they did not accumulate intraperitoneally administered Fluorogold. We traced their axonal projections by injecting a Cre-dependent vector (floxed-AAV2) expressing either GFP or mCherrry into the mRVLM of ChAT-Cre mice. Transduced neurons expressing GFP or mCherry were confined to the injection site and were exclusively ChAT-ir. Their axonal projections included the dorsal column nuclei, medullary trigeminal complex, cochlear nuclei, superior olivary complex and spinal cord lamina III. For control experiments, the floxed-AAV2 (mCherry) was injected into the RVLM of dopamine beta-hydroxylase-Cre mice. In these mice mCherry was exclusively expressed by RVLM catecholaminergic neurons. Consistent with data from rats, these catecholaminergic neurons targeted brain regions involved in autonomic and endocrine regulation. These regions were almost totally different from those innervated by the intermingled mRVLM-ChAT neurons. This study emphasizes the advantages of using Cre-driver mouse strains in combination with floxed-AAV2 to trace the axonal projections of chemically defined neuronal groups. Using this technique, we revealed previously unknown projections of mRVLM-ChAT neurons and showed that despite their close proximity to the cardiorespiratory region of the RVLM, these cholinergic neurons regulate sensory afferent information selectively and presumably have little to do with respiration or circulatory control. PMID:22460939

  15. Nerve Growth Factor Decreases in Sympathetic and Sensory Nerves of Rats with Chronic Heart Failure

    PubMed Central

    Lu, Jian

    2014-01-01

    Nerve growth factor (NGF) plays a critical role in the maintenance and survival of both sympathetic and sensory nerves. Also, NGF can regulate receptor expression and neuronal activity in the sympathetic and sensory neurons. Abnormalities in NGF regulation are observed in patients and animals with heart failure (HF). Nevertheless, the effects of chronic HF on the levels of NGF within the sympathetic and sensory nerves are not known. Thus, the ELISA method was used to assess the levels of NGF in the stellate ganglion (SG) and dorsal root ganglion (DRG) neurons of control rats and rats with chronic HF induced by myocardial infarction. Our data show for the first time that the levels of NGF were significantly decreased (P < 0.05) in the SG and DRG neurons 6–20 weeks after ligation of the coronary artery. In addition, a close relation was observed between the NGF levels and the left ventricular function. In conclusion, chronic HF impairs the expression of NGF in the sympathetic and sensory nerves. Given that sensory afferent nerves are engaged in the sympathetic nervous responses to somatic stimulation (i.e. muscle activity during exercise) via a reflex mechanism, our data indicate that NGF is likely responsible for the development of muscle reflex-mediated abnormal sympathetic responsiveness observed in chronic HF. PMID:24913185

  16. 4-Hydroxy-2-nonenal induces mitochondrial dysfunction and aberrant axonal outgrowth in adult sensory neurons that mimics features of diabetic neuropathy.

    PubMed

    Akude, Eli; Zherebitskaya, Elena; Roy Chowdhury, Subir K; Girling, Kimberly; Fernyhough, Paul

    2010-01-01

    Modification of proteins by 4-hydroxy-2-nonenal (4-HNE) has been proposed to cause neurotoxicity in a number of neurodegenerative diseases, including distal axonopathy in diabetic sensory neuropathy. We tested the hypothesis that exposure of cultured adult rat sensory neurons to 4-HNE would result in the formation of amino acid adducts on mitochondrial proteins and that this process would be associated with impaired mitochondrial function and axonal regeneration. In addition, we compared 4-HNE-induced axon pathology with that exhibited by neurons isolated from diabetic rats. Cultured adult rat dorsal root ganglion (DRG) sensory neurons were incubated with varying concentrations of 4-HNE. Cell survival, axonal morphology, and level of axon outgrowth were assessed. In addition, video microscopy of live cells, western blot, and immunofluorescent staining were utilized to detect protein adduct formation by 4-HNE and to localize actively respiring mitochondria. 4-HNE induced formation of protein adducts on cytoskeletal and mitochondrial proteins, and impaired axon regeneration by approximately 50% at 3 microM while having no effect on neuronal survival. 4-HNE initiated formation of aberrant axonal structures and caused the accumulation of mitochondria in these dystrophic structures. Neurons treated with 4-HNE exhibited a distal loss of active mitochondria. Finally, the distal axonopathy and the associated aberrant axonal structures generated by 4-HNE treatment mimicked axon pathology observed in DRG sensory neurons isolated from diabetic rats and replicated aspects of neurodegeneration observed in human diabetic sensory neuropathy.

  17. Visualization of Sensory Neurons and Their Projections in an Upper Motor Neuron Reporter Line.

    PubMed

    Genç, Barış; Lagrimas, Amiko Krisa Bunag; Kuru, Pınar; Hess, Robert; Tu, Michael William; Menichella, Daniela Maria; Miller, Richard J; Paller, Amy S; Özdinler, P Hande

    2015-01-01

    Visualization of peripheral nervous system axons and cell bodies is important to understand their development, target recognition, and integration into complex circuitries. Numerous studies have used protein gene product (PGP) 9.5 [a.k.a. ubiquitin carboxy-terminal hydrolase L1 (UCHL1)] expression as a marker to label sensory neurons and their axons. Enhanced green fluorescent protein (eGFP) expression, under the control of UCHL1 promoter, is stable and long lasting in the UCHL1-eGFP reporter line. In addition to the genetic labeling of corticospinal motor neurons in the motor cortex and degeneration-resistant spinal motor neurons in the spinal cord, here we report that neurons of the peripheral nervous system are also fluorescently labeled in the UCHL1-eGFP reporter line. eGFP expression is turned on at embryonic ages and lasts through adulthood, allowing detailed studies of cell bodies, axons and target innervation patterns of all sensory neurons in vivo. In addition, visualization of both the sensory and the motor neurons in the same animal offers many advantages. In this report, we used UCHL1-eGFP reporter line in two different disease paradigms: diabetes and motor neuron disease. eGFP expression in sensory axons helped determine changes in epidermal nerve fiber density in a high-fat diet induced diabetes model. Our findings corroborate previous studies, and suggest that more than five months is required for significant skin denervation. Crossing UCHL1-eGFP with hSOD1G93A mice generated hSOD1G93A-UeGFP reporter line of amyotrophic lateral sclerosis, and revealed sensory nervous system defects, especially towards disease end-stage. Our studies not only emphasize the complexity of the disease in ALS, but also reveal that UCHL1-eGFP reporter line would be a valuable tool to visualize and study various aspects of sensory nervous system development and degeneration in the context of numerous diseases.

  18. Calcium signal transmission in chick sensory neurones is diffusion based.

    PubMed

    Coatesworth, William; Bolsover, Stephen

    2008-03-01

    In many cells, the cytosol is an excitable medium through which calcium waves propagate by calcium induced calcium release (CICR). Many labs. have reported CICR in neurones subsequent to calcium influx through voltage gated channels. However, these have used long depolarizations. We have imaged calcium within chick sensory neurones following 50 ms depolarizations. Calcium signals travelled rapidly throughout the cell, such that changes at the cell centre were delayed by 24 ms compared to regions 3 microm from the plasma membrane. The nuclear envelope imposed a delay of 9 ms. A simple diffusion model with few unknowns gave good fits to the measured data, indicating that passive diffusion is responsible for signal transmission in these neurones. Simulations run without indicator dye did not reveal markedly different spatiotemporal dynamics, although concentration changes were larger. Simulations of calcium changes during action potentials revealed that large calcium transients occurring in the cytosol close to the nucleus are significantly attenuated by the nuclear envelope. Our results indicate that for the brief depolarisations that neurones will experience during normal signal processing calcium signals are transmitted by passive diffusion only. Diffusion is perfectly capable of transmitting the calcium signal into the interior of nerve cell bodies, and into the nucleoplasm.

  19. Peripheral Sensory Neurons Expressing Melanopsin Respond to Light

    PubMed Central

    Matynia, Anna; Nguyen, Eileen; Sun, Xiaoping; Blixt, Frank W.; Parikh, Sachin; Kessler, Jason; Pérez de Sevilla Müller, Luis; Habib, Samer; Kim, Paul; Wang, Zhe Z.; Rodriguez, Allen; Charles, Andrew; Nusinowitz, Steven; Edvinsson, Lars; Barnes, Steven; Brecha, Nicholas C.; Gorin, Michael B.

    2016-01-01

    The ability of light to cause pain is paradoxical. The retina detects light but is devoid of nociceptors while the trigeminal sensory ganglia (TG) contain nociceptors but not photoreceptors. Melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs) are thought to mediate light-induced pain but recent evidence raises the possibility of an alternative light responsive pathway independent of the retina and optic nerve. Here, we show that melanopsin is expressed in both human and mouse TG neurons. In mice, they represent 3% of small TG neurons that are preferentially localized in the ophthalmic branch of the trigeminal nerve and are likely nociceptive C fibers and high-threshold mechanoreceptor Aδ fibers based on a strong size-function association. These isolated neurons respond to blue light stimuli with a delayed onset and sustained firing, similar to the melanopsin-dependent intrinsic photosensitivity observed in ipRGCs. Mice with severe bilateral optic nerve crush exhibit no light-induced responses including behavioral light aversion until treated with nitroglycerin, an inducer of migraine in people and migraine-like symptoms in mice. With nitroglycerin, these same mice with optic nerve crush exhibit significant light aversion. Furthermore, this retained light aversion remains dependent on melanopsin-expressing neurons. Our results demonstrate a novel light-responsive neural function independent of the optic nerve that may originate in the peripheral nervous system to provide the first direct mechanism for an alternative light detection pathway that influences motivated behavior. PMID:27559310

  20. Sigma-1 Receptor Antagonism Restores Injury-Induced Decrease of Voltage-Gated Ca2+ Current in Sensory Neurons

    PubMed Central

    Pan, Bin; Guo, Yuan; Kwok, Wai-Meng; Hogan, Quinn

    2014-01-01

    Sigma-1 receptor (σ1R), an endoplasmic reticulum–chaperone protein, can modulate painful response after peripheral nerve injury. We have demonstrated that voltage-gated calcium current is inhibited in axotomized sensory neurons. We examined whether σ1R contributes to the sensory dysfunction of voltage-gated calcium channel (VGCC) after peripheral nerve injury through electrophysiological approach in dissociated rat dorsal root ganglion (DRG) neurons. Animals received either skin incision (Control) or spinal nerve ligation (SNL). Both σ1R agonists, (+)pentazocine (PTZ) and DTG [1,3-di-(2-tolyl)guanidine], dose dependently inhibited calcium current (ICa) with Ba2+ as charge carrier in control sensory neurons. The inhibitory effect of σ1R agonists on ICa was blocked by σ1R antagonist, BD1063 (1-[2-(3,4-dichlorophenyl)ethyl]-4-m​ethylpiperazine dihydrochloride) or BD1047 (N-[2-(3,4-dichlorophenyl)ethyl]-N-m​ethyl-2-(dimethylamino)ethylamine dihydrobromide). PTZ and DTG showed similar effect on ICa in axotomized fifth DRG neurons (SNL L5). Both PTZ and DTG shifted the voltage-dependent activation and steady-state inactivation of VGCC to the left and accelerated VGCC inactivation rate in both Control and axotomized L5 SNL DRG neurons. The σ1R antagonist, BD1063 (10 μM), increases ICa in SNL L5 neurons but had no effect on Control and noninjured fourth lumbar neurons in SNL rats. Together, the findings suggest that activation of σR1 decreases ICa in sensory neurons and may play a pivotal role in pain generation. PMID:24891452

  1. Analysis of the variation in use-dependent inactivation of high-threshold tetrodotoxin-resistant sodium currents recorded from rat sensory neurons.

    PubMed

    Tripathi, P K; Trujillo, L; Cardenas, C A; Cardenas, C G; de Armendi, A J; Scroggs, R S

    2006-12-28

    This study addressed variation in the use-dependent inactivation (UDI) of high-threshold tetrodotoxin-resistant Na+ currents (TTX-R currents) and action potential firing behavior among acutely isolated rat dorsal root ganglion (DRG) cells. UDI was quantified as the percent decrease in current amplitude caused by increasing the current activation rate from 0.1-1.0 Hz for 20 s. TTX-R current UDI varied from 6% to 66% among 122 DRG cells examined, suggesting the existence of two or more levels of UDI. The voltage-dependency of the TTX-R currents was consistent with Na(V)1.8, regardless of UDI. However, TTX-R currents with more UDI had a more negative voltage-dependency of inactivation, a greater tendency to enter slow inactivation, and a slower recovery rate from slow inactivation, compared with those with less UDI. TTX-R currents with more UDI ran down faster than those with less UDI. However, UDI itself changed little over time, regardless of the initial UDI level observed in a particular DRG cell. Together, these two observations suggest that individual DRG cells did not express mixtures of TTX-R channels that varied regarding UDI. TTX-R current UDI was correlated with expression of a low-threshold A-current and whole-cell capacitance, suggesting that it varied among different nociceptor types. Whole-cell inward currents (WCI-currents), recorded without channel blockers, also exhibited UDI. WCI-current UDI varied similarly to TTX-R current UDI in magnitude, and relative to whole-cell capacitance and A-current expression, suggesting that the WCI-currents were carried predominantly by TTX-R channels. DRG cells with more WCI-current UDI exhibited a greater decrease in action potential amplitude and number, and a greater increase in action potential threshold over seven ramp depolarizations, compared with DRG cells with less WCI-current UDI. Variation in UDI of Na(V)1.8 channels expressed by different nociceptor types could contribute to shaping their individual firing

  2. P2Y2 receptors mediate ATP-induced resensitization of TRPV1 expressed by kidney projecting sensory neurons.

    PubMed

    Wang, Hui; Wang, Donna H; Galligan, James J

    2010-06-01

    The transient receptor potential vanilloid type 1 (TRPV1) channel is a ligand-gated cation channel expressed by sensory nerves. P2Y receptors are G protein-coupled receptors that are also expressed by TRPV1-positive sensory neurons. Therefore, we studied interactions between P2Y receptors and TRPV1 function on kidney projecting sensory neurons. Application of Fast Blue (FB) to nerves surrounding the renal artery retrogradely labeled neurons in dorsal root ganglia of rats. Whole cell recording was performed on FB-labeled neurons maintained in primary culture. Capsaicin was used to activate TRPV1. Four types of kidney projecting neurons were identified based on capsaicin responses: 1) desensitizing (35%), 2) nondesensitizing (29%), 3) silent (3%), and 4) insensitive (30%). Silent neurons responded to capsaicin only after ATP (100 microM) pretreatment. ATP reversed desensitization in desensitizing neurons. Insensitive neurons never responded to capsaicin. UTP, a P2Y purinoceptor 2 (P2Y(2))/P2Y(4) receptor agonist, reversed capsaicin-induced TRPV1 desensitization. 2-methyl-thio-ATP (2-Me-S-ATP), a P2Y(1) receptor agonist, did not change desensitization. MRS 2179 and pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), drugs that block P2Y(1) receptors, did not block ATP-induced resensitization of TRPV1. Suramin, a P2Y(2) receptor antagonist, blocked resensitization caused by UTP. Immunocytochemical studies showed that FB-labeled neurons coexpressed P2Y(2) receptors and TRPV1. We conclude that P2Y(2) receptor activation can maintain TRPV1 function perhaps during sustained episodes of activity of kidney projecting sensory neurons.

  3. ESTRADIOL RAPIDLY MODULATES ODOR RESPONSES IN MOUSE VOMERONASAL SENSORY NEURONS

    PubMed Central

    CHERIAN, S.; LAM, Y. WAI; MCDANIELS, I.; STRUZIAK, M.; DELAY, R. J.

    2014-01-01

    In rodents, many social behaviors are driven by the sense of smell. The vomeronasal organ (VNO), part of the accessory olfactory system mediates many of these chemically driven behaviors. The VNO is heavily vascularized, and is readily accessible to circulating peptide or steroid hormones. Potentially, this allows circulating hormones to alter behavior through modulating the output of the primary sensory neurons in the VNO, the vomeronasal sensory neurons (VSNs). Based on this, we hypothesized that steroid hormones, in particular 17β-estradiol, would modulate activity of VSNs. In this paper, we show that the estrogen receptors, GPR30 and ERα, were present in VSNs and that estradiol may be synthesized locally in the VNO. Our results also showed that 17β-estradiol decreased responses of isolated VSNs to dilute urine, a potent natural stimulus, with respect to current amplitudes and depolarization. Further, 17β-estradiol increased the latency of the first action potential (AP) and the AP amplitude. Additionally, calcium responses to sulfated steroids (present in the low molecular weight fraction of urine) that act as ligands for apical vomeronasal receptors were decreased by 17β-estradiol. In conclusion, we show that estradiol modulates odorant responses mediated by VSNs and hence paves the way for future studies to better understand the mechanisms by which odorant mediated behavior is altered by endocrine status of the animal. PMID:24680884

  4. Sensory neurons do not induce motor neuron loss in a human stem cell model of spinal muscular atrophy.

    PubMed

    Schwab, Andrew J; Ebert, Allison D

    2014-01-01

    Spinal muscular atrophy (SMA) is an autosomal recessive disorder leading to paralysis and early death due to reduced SMN protein. It is unclear why there is such a profound motor neuron loss, but recent evidence from fly and mouse studies indicate that cells comprising the whole sensory-motor circuit may contribute to motor neuron dysfunction and loss. Here, we used induced pluripotent stem cells derived from SMA patients to test whether sensory neurons directly contribute to motor neuron loss. We generated sensory neurons from SMA induced pluripotent stem cells and found no difference in neuron generation or survival, although there was a reduced calcium response to depolarizing stimuli. Using co-culture of SMA induced pluripotent stem cell derived sensory neurons with control induced pluripotent stem cell derived motor neurons, we found no significant reduction in motor neuron number or glutamate transporter boutons on motor neuron cell bodies or neurites. We conclude that SMA sensory neurons do not overtly contribute to motor neuron loss in this human stem cell system.

  5. Uptake of nerve growth factor along peripheral and spinal axons of primary sensory neurons

    SciTech Connect

    Richardson, P.M.; Riopelle, R.J.

    1984-07-01

    To investigate the distribution of nerve growth factor (NGF) receptors on peripheral and central axons, (/sup 125/I)NGF was injected into the sciatic nerve or spinal cord of adult rats. Accumulation of (/sup 125/I)NGF in lumbar dorsal root ganglia was monitored by gamma emission counting and radioautography. (/sup 125/I)NGF, injected endoneurially in small quantities, was taken into sensory axons by a saturable process and was transported retrogradely to their cell bodies at a maximal rate of 2.5 to 7.5 mm/hr. Because very little (/sup 125/I)NGF reached peripheral terminals, the results were interpreted to indicate that receptors for NGF are present on nonterminal segments of sensory axons. The specificity and high affinity of NGF uptake were illustrated by observations that negligible amounts of gamma activity accumulated in lumbar dorsal root ganglia after comparable intraneural injection of (/sup 125/I) cytochrome C or (/sup 125/I)oxidized NGF. Similar techniques were used to demonstrate avid internalization and retrograde transport of (/sup 125/I)NGF by intraspinal axons arising from dorsal root ganglia. Following injection of (/sup 125/I)NGF into lumbar or cervical regions of the spinal cord, neuronal perikarya were clearly labeled in radioautographs of lumbar dorsal root ganglia. Sites for NGF uptake on primary sensory neurons in the adult rat are not restricted to peripheral axon terminals but are extensively distributed along both peripheral and central axons. Receptors on axons provide a mechanism whereby NGF supplied by glia could influence neuronal maintenance or axonal regeneration.

  6. Bilateral Neuropathy of Primary Sensory Neurons by the Chronic Compression of Multiple Unilateral DRGs.

    PubMed

    Xie, Ya-Bin; Zhao, Huan; Wang, Ying; Song, Kai; Zhang, Ming; Meng, Fan-Cheng; Yang, Yu-Jie; He, Yang-Song; Kuang, Fang; You, Si-Wei; You, Hao-Jun; Xu, Hui

    2016-01-01

    To mimic multilevel nerve root compression and intervertebral foramina stenosis in human, we established a new animal model of the chronic compression of unilateral multiple lumbar DRGs (mCCD) in the rat. A higher occurrence of signs of spontaneous pain behaviors, such as wet-dog shaking and spontaneous hind paw shrinking behaviors, was firstly observed from day 1 onward. In the meantime, the unilateral mCCD rat exhibited significant bilateral hind paw mechanical and cold allodynia and hyperalgesia, as well as a thermal preference to 30°C plate between 30 and 35°C. The expression of activating transcription factor 3 (ATF3) was significantly increased in the ipsilateral and contralateral all-sized DRG neurons after the mCCD. And the expression of CGRP was significantly increased in the ipsilateral and contralateral large- and medium-sized DRG neurons. ATF3 and CGRP expressions correlated to evoked pain hypersensitivities such as mechanical and cold allodynia on postoperative day 1. The results suggested that bilateral neuropathy of primary sensory neurons might contribute to bilateral hypersensitivity in the mCCD rat.

  7. Bilateral Neuropathy of Primary Sensory Neurons by the Chronic Compression of Multiple Unilateral DRGs

    PubMed Central

    Xie, Ya-Bin; Zhao, Huan; Wang, Ying; Song, Kai; Zhang, Ming; Meng, Fan-Cheng; Yang, Yu-Jie; He, Yang-Song; Kuang, Fang; You, Si-Wei; You, Hao-Jun; Xu, Hui

    2016-01-01

    To mimic multilevel nerve root compression and intervertebral foramina stenosis in human, we established a new animal model of the chronic compression of unilateral multiple lumbar DRGs (mCCD) in the rat. A higher occurrence of signs of spontaneous pain behaviors, such as wet-dog shaking and spontaneous hind paw shrinking behaviors, was firstly observed from day 1 onward. In the meantime, the unilateral mCCD rat exhibited significant bilateral hind paw mechanical and cold allodynia and hyperalgesia, as well as a thermal preference to 30°C plate between 30 and 35°C. The expression of activating transcription factor 3 (ATF3) was significantly increased in the ipsilateral and contralateral all-sized DRG neurons after the mCCD. And the expression of CGRP was significantly increased in the ipsilateral and contralateral large- and medium-sized DRG neurons. ATF3 and CGRP expressions correlated to evoked pain hypersensitivities such as mechanical and cold allodynia on postoperative day 1. The results suggested that bilateral neuropathy of primary sensory neurons might contribute to bilateral hypersensitivity in the mCCD rat. PMID:26819761

  8. Identification of a signaling cascade that maintains constitutive delta opioid receptor incompetence in peripheral sensory neurons.

    PubMed

    Brackley, Allison Doyle; Sarrami, Shayda; Gomez, Ruben; Guerrero, Kristi A; Jeske, Nathaniel A

    2017-04-05

    Mu opioid receptor (MOR) agonists are often used to treat severe pain, but can result in adverse side effects. To circumvent systemic side effects, targeting peripheral opioid receptors is an attractive alternative treatment for severe pain. Activation of the delta opioid receptor (DOR) produces similar analgesia with reduced side effects. However, until primed by inflammation, peripheral DOR is analgesically incompetent, raising interest in the mechanism. We recently identified a novel role for G protein-coupled receptor kinase 2 (GRK2) that renders DOR analgesically incompetent at the plasma membrane. However, the mechanism that maintains constitutive GRK2 association with DOR is unknown. Protein kinase A (PKA) phosphorylation of GRK2 at Ser685 targets it to the plasma membrane. A-kinase anchoring protein 79/150 (AKAP), residing at the plasma membrane in neurons, scaffolds PKA to target proteins to mediate downstream signal. Therefore, we sought to determine whether GRK2-mediated DOR desensitization is directed by PKA via AKAP scaffolding. Membrane fractions from cultured rat sensory neurons following AKAP siRNA-transfection and from AKAP-knockout mice, had less PKA activity, GRK2 Ser685 phosphorylation, and GRK2 plasma membrane targeting than controls. Site-directed mutagenesis revealed that GRK2 Ser685 phosphorylation drives GRK2s association with plasma membrane-associated DOR. Moreover, overexpression studies with AKAP mutants indicated that impaired AKAP-mediated PKA scaffolding significantly reduces DOR-GRK2 association at the plasma membrane and consequently increases DOR activity in sensory neurons without a priming event. These findings suggest that AKAP scaffolds PKA to increase plasma membrane targeting and phosphorylation of GRK2 to maintain DOR analgesic incompetence in peripheral sensory neurons.

  9. Integration of sensory quanta in cuneate nucleus neurons in vivo.

    PubMed

    Bengtsson, Fredrik; Brasselet, Romain; Johansson, Roland S; Arleo, Angelo; Jörntell, Henrik

    2013-01-01

    Discriminative touch relies on afferent information carried to the central nervous system by action potentials (spikes) in ensembles of primary afferents bundled in peripheral nerves. These sensory quanta are first processed by the cuneate nucleus before the afferent information is transmitted to brain networks serving specific perceptual and sensorimotor functions. Here we report data on the integration of primary afferent synaptic inputs obtained with in vivo whole cell patch clamp recordings from the neurons of this nucleus. We find that the synaptic integration in individual cuneate neurons is dominated by 4-8 primary afferent inputs with large synaptic weights. In a simulation we show that the arrangement with a low number of primary afferent inputs can maximize transfer over the cuneate nucleus of information encoded in the spatiotemporal patterns of spikes generated when a human fingertip contact objects. Hence, the observed distributions of synaptic weights support high fidelity transfer of signals from ensembles of tactile afferents. Various anatomical estimates suggest that a cuneate neuron may receive hundreds of primary afferents rather than 4-8. Therefore, we discuss the possibility that adaptation of synaptic weight distribution, possibly involving silent synapses, may function to maximize information transfer in somatosensory pathways.

  10. IB4-binding sensory neurons in the adult rat express a novel 3′ UTR-extended isoform of CaMK4 that is associated with its localization to axons

    PubMed Central

    Harrison, Benjamin J.; Flight, Robert M.; Gomes, Cynthia; Venkat, Gayathri; Ellis, Steven R; Sankar, Uma; Twiss, Jeffery L.; Rouchka, Eric C.; Petruska, Jeffrey C.

    2013-01-01

    Calcium/Calmodulin-dependent protein Kinase 4 (Gene and transcript: CaMK4; Protein: CaMKIV) is the nuclear effector of the Ca2+/Calmodulin Kinase (CaMK) pathway where it co-ordinates transcriptional responses. However, CaMKIV is present in the cytoplasm and axons of subpopulations of neurons, including some sensory neurons of the dorsal root ganglia (DRG), suggesting an extra-nuclear role for this protein. We observed that CaMKIV was expressed strongly in the cytoplasm and axons of a subpopulation of small diameter DRG neurons, most likely cutaneous nociceptors by virtue of their binding the isolectin IB4. In IB4+ spinal nerve axons, 20% of CaMKIV was co-localized with the endocytic marker Rab7 in axons that highly expressed CAM-Kinase-Kinase (CAMKK), an upstream activator of CaMKIV, suggesting a role for CaMKIV in signalling though signalling endosomes. Using fluorescent in situ hybridization (FISH) with riboprobes, we also observed that small diameter neurons expressed high levels of a novel 3' untranslated region (UTR) variant of CaMK4 mRNA. Using rapid amplification of cDNA ends (RACE), RT-PCR with gene-specific primers, and cDNA sequencing analyses we determined that the novel transcript contains an additional 10kb beyond the annotated gene terminus to a highly conserved alternate poly-adenylation site. qPCR analyses of fluorescent-activated cell sorted (FACS) DRG neurons confirmed that this 3'UTR-extended variant was preferentially expressed in IB4-binding neurons. Computational analyses of the 3'-UTR sequence predict that UTR-extension introduces consensus sites for RNA-binding proteins (RBPs) including the Embryonic Lethal Abnormal Vision (ELAV)/Hu family proteins. We consider the possible implications of axonal CaMKIV in the context of the unique properties of IB4-binding DRG neurons. PMID:23817991

  11. Proteasome inhibition induces DNA damage and reorganizes nuclear architecture and protein synthesis machinery in sensory ganglion neurons.

    PubMed

    Palanca, Ana; Casafont, Iñigo; Berciano, María T; Lafarga, Miguel

    2014-05-01

    Bortezomib is a reversible proteasome inhibitor used as an anticancer drug. However, its clinical use is limited since it causes peripheral neurotoxicity. We have used Sprague-Dawley rats as an animal model to investigate the cellular mechanisms affected by both short-term and chronic bortezomib treatments in sensory ganglia neurons. Proteasome inhibition induces dose-dependent alterations in the architecture, positioning, shape and polarity of the neuronal nucleus. It also produces DNA damage without affecting neuronal survival, and severe disruption of the protein synthesis machinery at the central cytoplasm accompanied by decreased expression of the brain-derived neurotrophic factor. As a compensatory or adaptive survival response against proteotoxic stress caused by bortezomib treatment, sensory neurons preserve basal levels of transcriptional activity, up-regulate the expression of proteasome subunit genes, and generate a new cytoplasmic perinuclear domain for protein synthesis. We propose that proteasome activity is crucial for controlling nuclear architecture, DNA repair and the organization of the protein synthesis machinery in sensory neurons. These neurons are primary targets of bortezomib neurotoxicity, for which reason their dysfunction may contribute to the pathogenesis of the bortezomib-induced peripheral neuropathy in treated patients.

  12. Coordinated Rhythmic Motion by Uncoupled Neuronal Oscillators with Sensory Feedback

    NASA Astrophysics Data System (ADS)

    Iwasaki, Tetsuya

    This paper explores the potential of biological oscillators as a basic unit for feedback control to achieve rhythmic motion of locomotory systems. Among those properties of biological control systems that are useful for engineering applications, we focus on decentralized coordination, that is, the ability of uncoupled neuronal oscillators to coordinate rhythmic body movements to achieve locomotion with the aid of local sensory feedback. We will consider the reciprocal inhibition oscillator (RIO) as a candidate for the basic control unit, and show that uncoupled RIOs can achieve decentralized coordination of a prototype mechanical rectifier (PMR) that captures essential dynamics underlying animal locomotion by a simple arm-disk configuration. Optimality of the induced locomotion is studied in comparison with analytical results we derive for statically optimal PMR locomotion.

  13. Membrane stiffening by STOML3 facilitates mechanosensation in sensory neurons.

    PubMed

    Qi, Yanmei; Andolfi, Laura; Frattini, Flavia; Mayer, Florian; Lazzarino, Marco; Hu, Jing

    2015-10-07

    Sensing force is crucial to maintain the viability of all living cells. Despite its fundamental importance, how force is sensed at the molecular level remains largely unknown. Here we show that stomatin-like protein-3 (STOML3) controls membrane mechanics by binding cholesterol and thus facilitates force transfer and tunes the sensitivity of mechano-gated channels, including Piezo channels. STOML3 is detected in cholesterol-rich lipid rafts. In mouse sensory neurons, depletion of cholesterol and deficiency of STOML3 similarly and interdependently attenuate mechanosensitivity while modulating membrane mechanics. In heterologous systems, intact STOML3 is required to maintain membrane mechanics to sensitize Piezo1 and Piezo2 channels. In C57BL/6N, but not STOML3(-/-) mice, tactile allodynia is attenuated by cholesterol depletion, suggesting that membrane stiffening by STOML3 is essential for mechanical sensitivity. Targeting the STOML3-cholesterol association might offer an alternative strategy for control of chronic pain.

  14. Nociceptive Sensory Neurons Drive Interleukin-23 Mediated Psoriasiform Skin Inflammation

    PubMed Central

    Riol-Blanco, Lorena; Ordovas-Montanes, Jose; Perro, Mario; Naval, Elena; Thiriot, Aude; Alvarez, David; Wood, John N.; von Andrian, Ulrich H.

    2014-01-01

    The skin has a dual function as a barrier and a sensory interface between the body and the environment. To protect against invading pathogens, the skin harbors specialized immune cells, including dermal dendritic cells (DDCs) and interleukin (IL)-17 producing γδ T cells (γδT17), whose aberrant activation by IL-23 can provoke psoriasis-like inflammation1–4. The skin is also innervated by a meshwork of peripheral nerves consisting of relatively sparse autonomic and abundant sensory fibers. Interactions between the autonomic nervous system and immune cells in lymphoid organs are known to contribute to systemic immunity, but how peripheral nerves regulate cutaneous immune responses remains unclear5,6. Here, we have exposed the skin of mice to imiquimod (IMQ), which induces IL-23 dependent psoriasis-like inflammation7,8. We show that a subset of sensory neurons expressing the ion channels TRPV1 and NaV1.8 is essential to drive this inflammatory response. Imaging of intact skin revealed that a large fraction of DDCs, the principal source of IL-23, is in close contact with these nociceptors. Upon selective pharmacological or genetic ablation of nociceptors9–11, DDCs failed to produce IL-23 in IMQ exposed skin. Consequently, the local production of IL-23 dependent inflammatory cytokines by dermal γδT17 cells and the subsequent recruitment of inflammatory cells to the skin were dramatically reduced. Intradermal injection of IL-23 bypassed the requirement for nociceptor communication with DDCs and restored the inflammatory response12. These findings indicate that TRPV1+NaV1.8+ nociceptors, by interacting with DDCs, regulate the IL-23/IL-17 pathway and control cutaneous immune responses. PMID:24759321

  15. Nociceptive sensory neurons drive interleukin-23-mediated psoriasiform skin inflammation.

    PubMed

    Riol-Blanco, Lorena; Ordovas-Montanes, Jose; Perro, Mario; Naval, Elena; Thiriot, Aude; Alvarez, David; Paust, Silke; Wood, John N; von Andrian, Ulrich H

    2014-06-05

    The skin has a dual function as a barrier and a sensory interface between the body and the environment. To protect against invading pathogens, the skin harbours specialized immune cells, including dermal dendritic cells (DDCs) and interleukin (IL)-17-producing γδ T (γδT17) cells, the aberrant activation of which by IL-23 can provoke psoriasis-like inflammation. The skin is also innervated by a meshwork of peripheral nerves consisting of relatively sparse autonomic and abundant sensory fibres. Interactions between the autonomic nervous system and immune cells in lymphoid organs are known to contribute to systemic immunity, but how peripheral nerves regulate cutaneous immune responses remains unclear. We exposed the skin of mice to imiquimod, which induces IL-23-dependent psoriasis-like inflammation. Here we show that a subset of sensory neurons expressing the ion channels TRPV1 and Nav1.8 is essential to drive this inflammatory response. Imaging of intact skin revealed that a large fraction of DDCs, the principal source of IL-23, is in close contact with these nociceptors. Upon selective pharmacological or genetic ablation of nociceptors, DDCs failed to produce IL-23 in imiquimod-exposed skin. Consequently, the local production of IL-23-dependent inflammatory cytokines by dermal γδT17 cells and the subsequent recruitment of inflammatory cells to the skin were markedly reduced. Intradermal injection of IL-23 bypassed the requirement for nociceptor communication with DDCs and restored the inflammatory response. These findings indicate that TRPV1(+)Nav1.8(+) nociceptors, by interacting with DDCs, regulate the IL-23/IL-17 pathway and control cutaneous immune responses.

  16. Distinct signaling of Drosophila chemoreceptors in olfactory sensory neurons

    PubMed Central

    Cao, Li-Hui; Jing, Bi-Yang; Yang, Dong; Zeng, Xiankun; Shen, Ying; Tu, Yuhai; Luo, Dong-Gen

    2016-01-01

    In Drosophila, olfactory sensory neurons (OSNs) rely primarily on two types of chemoreceptors, odorant receptors (Ors) and ionotropic receptors (Irs), to convert odor stimuli into neural activity. The cellular signaling of these receptors in their native OSNs remains unclear because of the difficulty of obtaining intracellular recordings from Drosophila OSNs. Here, we developed an antennal preparation that enabled the first recordings (to our knowledge) from targeted Drosophila OSNs through a patch-clamp technique. We found that brief odor pulses triggered graded inward receptor currents with distinct response kinetics and current–voltage relationships between Or- and Ir-driven responses. When stimulated with long-step odors, the receptor current of Ir-expressing OSNs did not adapt. In contrast, Or-expressing OSNs showed a strong Ca2+-dependent adaptation. The adaptation-induced changes in odor sensitivity obeyed the Weber–Fechner relation; however, surprisingly, the incremental sensitivity was reduced at low odor backgrounds but increased at high odor backgrounds. Our model for odor adaptation revealed two opposing effects of adaptation, desensitization and prevention of saturation, in dynamically adjusting odor sensitivity and extending the sensory operating range. PMID:26831094

  17. Identification of motor neurons and a mechanosensitive sensory neuron in the defecation circuitry of Drosophila larvae

    PubMed Central

    Zhang, Wei; Yan, Zhiqiang; Li, Bingxue; Jan, Lily Yeh; Jan, Yuh Nung

    2014-01-01

    Defecation allows the body to eliminate waste, an essential step in food processing for animal survival. In contrast to the extensive studies of feeding, its obligate counterpart, defecation, has received much less attention until recently. In this study, we report our characterizations of the defecation behavior of Drosophila larvae and its neural basis. Drosophila larvae display defecation cycles of stereotypic frequency, involving sequential contraction of hindgut and anal sphincter. The defecation behavior requires two groups of motor neurons that innervate hindgut and anal sphincter, respectively, and can excite gut muscles directly. These two groups of motor neurons fire sequentially with the same periodicity as the defecation behavior, as revealed by in vivo Ca2+ imaging. Moreover, we identified a single mechanosensitive sensory neuron that innervates the anal slit and senses the opening of the intestine terminus. This anus sensory neuron relies on the TRP channel NOMPC but not on INACTIVE, NANCHUNG, or PIEZO for mechanotransduction. DOI: http://dx.doi.org/10.7554/eLife.03293.001 PMID:25358089

  18. Role of calcium ions in the positive interaction between TRPA1 and TRPV1 channels in bronchopulmonary sensory neurons.

    PubMed

    Hsu, Chun-Chun; Lee, Lu-Yuan

    2015-06-15

    Both transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1) receptors are abundantly expressed in bronchopulmonary C-fiber sensory nerves and can be activated by a number of endogenous inflammatory mediators. A recent study has reported a synergistic effect of simultaneous TRPA1 and TRPV1 activations in vagal pulmonary C-fiber afferents in anesthetized rats, but its underlying mechanism was not known. This study aimed to characterize a possible interaction between these two TRP channels and to investigate the potential role of Ca(2+) as a mediator of this interaction in isolated rat vagal pulmonary sensory neurons. Using the perforated patch-clamp recording technique, our study demonstrated a distinct positive interaction occurring abruptly between TRPA1 and TRPV1 when they were activated simultaneously by their respective agonists, capsaicin (Cap) and allyl isothiocyanate (AITC), at near-threshold concentrations in these neurons. AITC at this low concentration evoked only minimal or undetectable responses, but it markedly amplified the Cap-evoked current in the same neurons. This potentiating effect was eliminated when either AITC or Cap was replaced by non-TRPA1 and non-TRPV1 chemical activators of these neurons, demonstrating the selectivity of the interaction between these two TRP channels. Furthermore, when Ca(2+) was removed from the extracellular solution, the synergistic effect of Cap and AITC on pulmonary sensory neurons was completely abrogated, clearly indicating a critical role of Ca(2+) in mediating the action. These results suggest that this TRPA1-TRPV1 interaction may play a part in regulating the sensitivity of pulmonary sensory neurons during airway inflammatory reaction.

  19. Atomoxetine modulates spontaneous and sensory-evoked discharge of locus coeruleus noradrenergic neurons

    PubMed Central

    Bari, A.; Aston-Jones, G.

    2012-01-01

    Atomoxetine (ATM) is a potent norepinephrine (NE) uptake inhibitor and increases both NE and dopamine synaptic levels in prefrontal cortex, where it is thought to exert its beneficial effects on attention and impulsivity. At the behavioral level, ATM has been shown to cause improvements on measures of executive functions, such as response inhibition, working memory and attentional set shifting across different species. However, the exact mechanism of action for ATM’s effects on cognition is still not clear. One possible target for the cognitive enhancing effects of ATM is the noradrenergic locus coeruleus (LC), the only source of NE to key forebrain areas such as cerebral cortex and hippocampus. Although it is known that ATM increases NE availability overall by blocking reuptake of NE, the effects of this agent on impulse activity of LC neurons have not been reported. Here, the effect of ATM (0.1 – 1 mg/kg, ip) on NE-LC neurons was investigated by recording extracellular activity of LC neurons in isoflurane-anesthetized rats. ATM caused a significant decrease of the tonic activity of LC single-units, although leaving intact the sensory-evoked excitatory component of LC phasic response. Moreover, the magnitude of the inhibitory component of LC response to paw stimulation was increased after 1 mg/kg of ATM and its duration was prolonged at 0.3 mg/kg. Together, these effects of ATM produced an increase in the phasic-to-tonic ratio of LC phasic response to sensory stimulation. ATM also modulated the average sensory-evoked local field potential (LFP) and spike-field coherence in LC depending on the dose tested. The lower dose (0.1 mg/kg) significantly decreased early positive and negative components of the sensory-evoked LFP response. Higher doses (0.3–1 mg/kg) initially increased and then decreased the amplitude of components of the evoked fields, whereas the spike-field coherence was enhanced by 1 mg/kg ATM across frequency bands. Finally, coherence between LC

  20. Phenotyping the Function of TRPV1-Expressing Sensory Neurons by Targeted Axonal Silencing

    PubMed Central

    Brenneis, Christian; Kistner, Katrin; Puopolo, Michelino; Segal, David; Roberson, David; Sisignano, Marco; Labocha, Sandra; Ferreirós, Nerea; Strominger, Amanda; Cobos, Enrique J.; Ghasemlou, Nader; Geisslinger, Gerd; Reeh, Peter W.; Bean, Bruce P.; Woolf, Clifford J.

    2013-01-01

    Specific somatosensations may be processed by different subsets of primary afferents. C-fibers expressing heat-sensitive TRPV1 channels are proposed, for example, to be heat but not mechanical pain detectors. To phenotype in rats the sensory function of TRPV1+ afferents, we rapidly and selectively silenced only their activity, by introducing the membrane-impermeant sodium channel blocker QX-314 into these axons via the TRPV1 channel pore. Using tandem mass spectrometry we show that upon activation with capsaicin, QX-314 selectively accumulates in the cytosol only of TRPV1-expressing cells, and not in control cells. Exposure to QX-314 and capsaicin induces in small DRG neurons a robust sodium current block within 30 s. In sciatic nerves, application of extracellular QX-314 with capsaicin persistently reduces C-fiber but not A-fiber compound action potentials and this effect does not occur in TRPV1−/− mice. Behavioral phenotyping after selectively silencing TRPV1+ sciatic nerve axons by perineural injections of QX-314 and capsaicin reveals deficits in heat and mechanical pressure but not pinprick or light touch perception. The response to intraplantar capsaicin is substantially reduced, as expected. During inflammation, silencing TRPV1+ axons abolishes heat, mechanical, and cold hyperalgesia but tactile and cold allodynia remain following peripheral nerve injury. These results indicate that TRPV1-expressing sensory neurons process particular thermal and mechanical somatosensations, and that the sensory channels activated by mechanical and cold stimuli to produce pain in naive/inflamed rats differ from those in animals after peripheral nerve injury. PMID:23283344

  1. Latent herpes simplex virus infection of sensory neurons alters neuronal gene expression.

    PubMed

    Kramer, Martha F; Cook, W James; Roth, Frederick P; Zhu, Jia; Holman, Holly; Knipe, David M; Coen, Donald M

    2003-09-01

    The persistence of herpes simplex virus (HSV) and the diseases that it causes in the human population can be attributed to the maintenance of a latent infection within neurons in sensory ganglia. Little is known about the effects of latent infection on the host neuron. We have addressed the question of whether latent HSV infection affects neuronal gene expression by using microarray transcript profiling of host gene expression in ganglia from latently infected versus mock-infected mouse trigeminal ganglia. (33)P-labeled cDNA probes from pooled ganglia harvested at 30 days postinfection or post-mock infection were hybridized to nylon arrays printed with 2,556 mouse genes. Signal intensities were acquired by phosphorimager. Mean intensities (n = 4 replicates in each of three independent experiments) of signals from mock-infected versus latently infected ganglia were compared by using a variant of Student's t test. We identified significant changes in the expression of mouse neuronal genes, including several with roles in gene expression, such as the Clk2 gene, and neurotransmission, such as genes encoding potassium voltage-gated channels and a muscarinic acetylcholine receptor. We confirmed the neuronal localization of some of these transcripts by using in situ hybridization. To validate the microarray results, we performed real-time reverse transcriptase PCR analyses for a selection of the genes. These studies demonstrate that latent HSV infection can alter neuronal gene expression and might provide a new mechanism for how persistent viral infection can cause chronic disease.

  2. Sciatic nerve injury induces apoptosis of dorsal root ganglion satellite glial cells and selectively modifies neurosteroidogenesis in sensory neurons.

    PubMed

    Schaeffer, Véronique; Meyer, Laurence; Patte-Mensah, Christine; Eckert, Anne; Mensah-Nyagan, Ayikoe G

    2010-01-15

    Neurosteroids are synthesized either by glial cells, by neurons, or within the context of neuron-glia cross-talk. Various studies suggested neurosteroid involvement in the control of neurodegeneration but there is no evidence showing that the natural protection of nerve cells against apoptosis directly depends on their own capacity to produce neuroprotective neurosteroids. Here, we investigated the interactions between neurosteroidogenesis and apoptosis occurring in sensory structures of rats subjected to neuropathic pain generated by sciatic nerve chronic constriction injury (CCI). Using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), we observed no apoptotic cells in the spinal cord up to 30 days after CCI although pain symptoms such as mechano-allodynia, thermal and mechanical hyperalgesia were evidenced with the Hargreaves's behavioral and von Frey filament tests. In contrast, double-labeling experiments combining TUNEL and immunostaining with antibodies against glutamine synthetase or neuronal nuclei protein revealed apoptosis occurrence in satellite glial cells (SGC) (not in neurons) of CCI rat ipsilateral dorsal root ganglia (DRG) at day 30 after injury. Pulse-chase experiments coupled with high performance liquid chromatography and flow scintillation detection showed that, among numerous biosynthetic pathways converting [(3)H]pregnenolone into various [(3)H]neurosteroids, only [(3)H]estradiol formation was selectively modified and upregulated in DRG of CCI rats. Consistently, immunohistochemical investigations localized aromatase (estradiol-synthesizing enzyme) in DRG neurons but not in SGC. Pharmacological inhibition of aromatase caused apoptosis of CCI rat DRG neurons. Altogether, our results suggest that endogenously produced neurosteroids such as estradiol may be pivotal for the protection of DRG sensory neurons against sciatic nerve CCI-induced apoptosis.

  3. Vitamin D deficiency leads to sensory and sympathetic denervation of the rat synovium

    PubMed Central

    Tague, Sarah E.; Smith, Peter G.

    2014-01-01

    Vitamin D deficiency is associated with increased susceptibility to inflammatory arthritis. Sensory and sympathetic synovial nerves are critical to the development of inflammatory arthritis and spontaneously degenerate in the early phases of disease. These nerves contain vitamin D receptors and vitamin D influences nerve growth and neurotrophin expression. We therefore examined the density of synovial nerves and neurotrophin-containing cells in vitamin D deficient rats. Seven week old Sprague Dawley rats were fed either control or vitamin D deficient diets for four weeks. Knee synovium sections extending from patella to meniscus were immunostained for total nerves, myelinated and unmyelinated nerves, sympathetic nerves, peptidergic and non-peptidergic sensory nerves, and neurotrophins and immune cell markers. In control rats, intimal innervation by unmyelinated sensory fibers was denser than subintimal innervation. In contrast, sympathetic innervation was confined to the subintima. Many sensory axons contained markers for both peptidergic and non-peptidergic nerves. NGF was primarily expressed by intimal CD163-negative type B synoviocytes, while neurturin, a ligand selective for non-peptidergic sensory neurons, was expressed by synovial mast cells. In vitamin D deficient rats, there were significant reductions in sensory nerves in the intima and sympathetic nerves in the subintima. While there was no significant change in NGF-immunoreactivity, the number of neurturin-expressing mast cells was significantly reduced in the intima, suggesting that intimal reductions in sensory nerves may be related to reductions in neurturin. Vitamin D deficiency therefore may increase susceptibility to inflammatory arthritis by depleting sensory and sympathetic synovial nerves as a result of reduced synovial neurotrophin content. PMID:25193239

  4. Interhemispheric modulation of sensory transmission in the primary somatosensory cortex of rats.

    PubMed

    Shin, H C; Won, C K; Jung, S C; Oh, S; Park, S; Sohn, J H

    1997-07-18

    Single unit responses of the primary somatosensory (SI) cortical neurons to the stimulation of the forepaw single digit were monitored in anesthetized rats before and after subcutaneous injection of lidocaine to an ipsilateral homologous receptive field (IHRF). Quantitative determination of the temporal changes of afferent sensory transmission was done by analyzing poststimulus time histograms of unit responses. Temporary deafferentation to the IHRF induced immediate, but reversible suppression of afferent sensory transmission in the SI cortex and this suppression lasts up to 35 min post-deafferentation period (during 10-15 min, -21.81 +/- 5.9%, P < 0.01). This result suggests that temporary absence of afferent inflow from the digit to the SI cortex may exert interhemispheric modulation of afferent sensory transmission in the opposite somatosensory cortex of anesthetized rats.

  5. Nonlinear high-order mode locking in stochastic sensory neurons

    NASA Astrophysics Data System (ADS)

    Rowe, Michael; Afghan, Muhammad; Neiman, Alexander

    2004-03-01

    Excitable systems demonstrate various mode locking regimes when driven by periodic external signals. With noise taken into account, such regimes represent complex nonlinear responses which depend crucially on the frequency and amplitude of the periodic drive as well as on the noise intensity. We study this using a computational model of a stochastic Hodgkin-Huxley neuron in combination with the turtle vestibular sensory system as an experimental model. A bifurcation analysis of the model is performed. Extracellular recordings from primary vestibular afferent neurons with two types of stimuli are used in the experimental study. First, mechanical stimuli applied to the labyrinth allow us to study the responses of the entire system, including transduction by the hair cells and spike generation in the primary afferents. Second, a galvanic stimuli applied directly to an afferent are used to study the responses of afferent spike generator directly. The responses to galvanic stimuli reveal multiple high-order mode locking regimes which are well reproduced in numerical simulation. Responses to mechanical stimulation are characterized by larger variability so that fewer mode-locking regimes can be observed.

  6. The role of the ETS gene PEA3 in the development of motor and sensory neurons.

    PubMed

    Ladle, David R; Frank, Eric

    2002-12-01

    The ETS family of transcription factors includes two members, ER81 and PEA3, which are expressed in groups of sensory and motor neurons supplying individual muscles. To investigate a possible role of these genes in determining sensory and/or motor neuron phenotype, we studied mice in which each of these genes was deleted. In contrast to the deletion of ER81, which blocks the formation of projections from muscle sensory neurons to motor neurons in the spinal cord, deletion of PEA3 causes no obvious effects on sensory neurons or on their synaptic connections with motor neurons. PEA3 does play a major role in the formation of some brachial motoneurons however. Motoneurons innervating the cutaneous maximus muscle, which are normally PEA3(+), fail to develop normally so that postnatally the muscle is innervated by few motoneurons and is severely atrophic. Other studies suggest that these motoneurons initially appear during development but fail to contact their normal muscle targets.

  7. Acid-sensing ion channel subtype 3 function and immunolabelling increases in skeletal muscle sensory neurons following femoral artery occlusion.

    PubMed

    Xing, Jihong; Lu, Jian; Li, Jianhua

    2012-03-01

    Sympathetic nerve activity and arterial blood pressure responses to static hindlimb muscle contractions are greater in rats with femoral arteries that were previously ligated (24-72 h earlier) than in control rats. Studies further demonstrate that acid-sensing ion channel subtype 3 (ASIC(3)) in thin-fibre muscle afferents contributes to the amplified reflex muscle responses observed in occluded rats, probably due to enhanced ASIC(3) expression in muscle sensory neurons. The purpose of this study was to characterize acid-induced current with activation of ASIC(3) in dorsal root ganglion (DRG) neurons of control rats and rats with 24 h of femoral occlusion using whole-cell patch clamp methods. Also, immunohistochemistry was employed to examine existence of ASIC(3) expression in DRG neurons of thin-fibre afferents. DRG neurons from 4- to 6-week-old rats were labelled by injecting the fluorescence tracer DiI into the hindlimb muscles 4-5 days prior to the recording experiments. The results of this study show that ∼90% of current responses evoked by pH 6.7 in DRG neurons innervating the hindlimb muscles are ASIC(3)-like. The peak current amplitude to pH 6.7 is significantly attenuated with application of rAPETx2, a specific ASIC(3) antagonist. In addition, ASIC(3)-like current responses to pH 6.7 are observed in small, medium and large DRG neurons, and size distribution of DRG neurons is similar in control and occluded animals. However, the peak current amplitude of DRG neuron response induced by ASIC(3) stimulation is larger in occluded rats than that in control rats. Moreover, the percentage of DRG neurons with ASIC(3)-like currents is greater after arterial occlusion compared with control. Furthermore, results from double immunofluorescence experiments show that femoral artery occlusion mainly augments ASIC(3) expression within DRG neurons projecting C-fibre afferents. Taken together, these data suggest that (1) the majority of current responses to pH 6.7 are ASIC

  8. Genomics of Mature and Immature Olfactory Sensory Neurons

    PubMed Central

    Nickell, Melissa D.; Breheny, Patrick; Stromberg, Arnold J.; McClintock, Timothy S.

    2014-01-01

    The continuous replacement of neurons in the olfactory epithelium provides an advantageous model for investigating neuronal differentiation and maturation. By calculating the relative enrichment of every mRNA detected in samples of mature mouse olfactory sensory neurons (OSNs), immature OSNs, and the residual population of neighboring cell types, and then comparing these ratios against the known expression patterns of >300 genes, enrichment criteria that accurately predicted the OSN expression patterns of nearly all genes were determined. We identified 847 immature OSN-specific and 691 mature OSN-specific genes. The control of gene expression by chromatin modification and transcription factors, and neurite growth, protein transport, RNA processing, cholesterol biosynthesis, and apoptosis via death domain receptors, were overrepresented biological processes in immature OSNs. Ion transport (ion channels), presynaptic functions, and cilia-specific processes were overrepresented in mature OSNs. Processes overrepresented among the genes expressed by all OSNs were protein and ion transport, ER overload response, protein catabolism, and the electron transport chain. To more accurately represent gradations in mRNA abundance and identify all genes expressed in each cell type, classification methods were used to produce probabilities of expression in each cell type for every gene. These probabilities, which identified 9,300 genes expressed in OSNs, were 96% accurate at identifying genes expressed in OSNs and 86% accurate at discriminating genes specific to mature and immature OSNs. This OSN gene database not only predicts the genes responsible for the major biological processes active in OSNs, but also identifies thousands of never before studied genes that support OSN phenotypes. PMID:22252456

  9. TRPA1 modulates mechanotransduction in cutaneous sensory neurons.

    PubMed

    Kwan, Kelvin Y; Glazer, Joshua M; Corey, David P; Rice, Frank L; Stucky, Cheryl L

    2009-04-15

    Transient receptor potential ankyrin 1 (TRPA1) is expressed by nociceptive neurons of the dorsal root ganglia (DRGs) and trigeminal ganglia, but its roles in cold and mechanotransduction are controversial. To determine the contribution of TRPA1 to cold and mechanotransduction in cutaneous primary afferent terminals, we used the ex vivo skin-nerve preparation from Trpa1(+/+), Trpa1(+/-), and Trpa1(-/-) adult mouse littermates. Cutaneous fibers from TRPA1-deficient mice showed no deficits in acute cold sensitivity, but they displayed striking deficits in mechanical response properties. C-fiber nociceptors from Trpa1(-/-) mice exhibited action potential firing rates 50% lower than those in wild-type C-fibers across a wide range of force intensities. Adelta-fiber mechanonociceptors also had reduced firing, but only at high intensity forces (>100 mN). Surprisingly, the firing rates of low-threshold Abeta and D-hair mechanoreceptive fibers were also altered. TRPA1 protein and mRNA expression was assessed in DRG neurons and cutaneous innervation by using Trpa1 in situ hybridization, an antibody for TRPA1, and an antibody for placental alkaline phosphatase (PLAP) in mice in which PLAP was substituted for Trpa1. DRG neurons of all sizes expressed Trpa1 mRNA or PLAP immunoreactivity. TRPA1 or PLAP immunolabeling was detected not only on many thin-caliber axons and intraepidermal endings but also on many large-caliber axons as well as lanceolate and Meissner endings. Epidermal and hair follicle keratinocytes also express TRPA1 message and protein. We propose that TRPA1 modulates mechanotransduction via a cell-autonomous mechanism in nociceptor terminals and possibly through a modulatory role in keratinocytes, which may interact with sensory terminals to modify their mechanical firing properties.

  10. Nav1.7 is the predominant sodium channel in rodent olfactory sensory neurons

    PubMed Central

    2011-01-01

    Background Voltage-gated sodium channel Nav1.7 is preferentially expressed in dorsal root ganglion (DRG) and sympathetic neurons within the peripheral nervous system. Homozygous or compound heterozygous loss-of-function mutations in SCN9A, the gene which encodes Nav1.7, cause congenital insensitivity to pain (CIP) accompanied by anosmia. Global knock-out of Nav1.7 in mice is neonatal lethal reportedly from starvation, suggesting anosmia. These findings led us to hypothesize that Nav1.7 is the main sodium channel in the peripheral olfactory sensory neurons (OSN, also known as olfactory receptor neurons). Methods We used multiplex PCR-restriction enzyme polymorphism, in situ hybridization and immunohistochemistry to determine the identity of sodium channels in rodent OSNs. Results We show here that Nav1.7 is the predominant sodium channel transcript, with low abundance of other sodium channel transcripts, in olfactory epithelium from rat and mouse. Our in situ hybridization data show that Nav1.7 transcripts are present in rat OSNs. Immunostaining of Nav1.7 and Nav1.6 channels in rat shows a complementary accumulation pattern with Nav1.7 in peripheral presynaptic OSN axons, and Nav1.6 primarily in postsynaptic cells and their dendrites in the glomeruli of the olfactory bulb within the central nervous system. Conclusions Our data show that Nav1.7 is the dominant sodium channel in rat and mouse OSN, and may explain anosmia in Nav1.7 null mouse and patients with Nav1.7-related CIP. PMID:21569247

  11. In vivo differential susceptibility of sensory neurons to rabies virus infection.

    PubMed

    Velandia-Romero, Myriam L; Castellanos, Jaime E; Martínez-Gutiérrez, Marlén

    2013-08-20

    There is controversy with regard to the entry pathway of the rabies virus (RABV) into the central nervous system (CNS). Some authors have suggested that the virus inoculated at the periphery is captured and transported to CNS only by motor neurons; however, it has been reported that dorsal root ganglia (DRG) sensory neurons capture and transport the virus to the spinal cord (SC) and then to the brain. It is probable that preferences for one pathway or another depend on the site of inoculation and the post-infection time. Therefore, in the present study, we evaluated different vertebral segments and post-infection times, along with the location, number, and subpopulation of sensory neurons susceptible to infection after inoculating RABV in the footpads of adult mice. It was noted that the virus inoculated in the footpad preferentially entered the CNS through the large-sized DRG sensory neurons, while infection of the motor neurons occurred later. Further, it was found that the virus was dispersed in spinal cord trans-synaptically through the interneurons, arriving at both sensory neurons and contralateral motor neurons. In conclusion, we observed that RABV inoculated in the plantar footpad is captured preferentially by large sensory neurons and is transported to the DRG, where it replicates and is spread to the SC using transynaptic jumps, infecting sensory and motor neurons at the same level before ascending to the brain.

  12. Do sensory neurons mediate adaptive cytoprotection of gastric mucosa against bile acid injury?

    PubMed

    Mercer, D W; Ritchie, W P; Dempsey, D T

    1992-01-01

    Pretreatment with the mild irritant 1 mmol acidified taurocholate protects the gastric mucosa from the injury induced by the subsequent application of 5 mmol acidified taurocholate, a phenomenon referred to as "adaptive cytoprotection." How this occurs remains an enigma. The purpose of this study was to investigate the role of sensory neurons and mucus secretion in this phenomenon. Prior to injury with 5 mmol acidified taurocholate (pH 1.2), the stomachs of six groups of rats were subjected to the following protocol. Two groups were topically pretreated with either saline or the mild irritant 1 mmol acidified taurocholate. Two other groups received the topical anesthetic 1% lidocaine prior to pretreatment with either saline or 1 mmol acidified taurocholate. The last two groups got the mucolytic agent 10% N-acetylcysteine (NAC) after pretreatment with either saline or 1 mmol acidified taurocholate. Injury was assessed by measuring net transmucosal ion fluxes, luminal appearance of deoxyribonucleic acid (DNA), and gross and histologic injury. Pretreatment with the mild irritant 1 mmol acidified taurocholate significantly decreased bile acid-induced luminal ion fluxes and DNA accumulation, suggesting mucosal protection (corroborated by gross and histologic injury analysis). This effect was negated by lidocaine but not by NAC. Thus, it appears that sensory neurons, and not increased mucus secretion, play a critical role in adaptive cytoprotection.

  13. Cannabinoid WIN 55,212-2 regulates TRPV1 phosphorylation in sensory neurons.

    PubMed

    Jeske, Nathaniel A; Patwardhan, Amol M; Gamper, Nikita; Price, Theodore J; Akopian, Armen N; Hargreaves, Kenneth M

    2006-10-27

    Cannabinoids are known to have multiple sites of action in the nociceptive system, leading to reduced pain sensation. However, the peripheral mechanism(s) by which this phenomenon occurs remains an issue that has yet to be resolved. Because phosphorylation of TRPV1 (transient receptor potential subtype V1) plays a key role in the induction of thermal hyperalgesia in inflammatory pain models, we evaluated whether the cannabinoid agonist WIN 55,212-2 (WIN) regulates the phosphorylation state of TRPV1. Here, we show that treatment of primary rat trigeminal ganglion cultures with WIN led to dephosphorylation of TRPV1, specifically at threonine residues. Utilizing Chinese hamster ovary cell lines, we demonstrate that Thr(144) and Thr(370) were dephosphorylated, leading to desensitization of the TRPV1 receptor. This post-translational modification occurred through activation of the phosphatase calcineurin (protein phosphatase 2B) following WIN treatment. Furthermore, knockdown of TRPA1 (transient receptor potential subtype A1) expression in sensory neurons by specific small interfering RNA abolished the WIN effect on TRPV1 dephosphorylation, suggesting that WIN acts through TRPA1. We also confirm the importance of TRPA1 in WIN-induced dephosphorylation of TRPV1 in Chinese hamster ovary cells through targeted expression of one or both receptor channels. These results imply that the cannabinoid WIN modulates the sensitivity of sensory neurons to TRPV1 activation by altering receptor phosphorylation. In addition, our data could serve as a useful strategy in determining the potential use of certain cannabinoids as peripheral analgesics.

  14. CaV3.2 T-type calcium channels in peripheral sensory neurons are important for mibefradil-induced reversal of hyperalgesia and allodynia in rats with painful diabetic neuropathy.

    PubMed

    Obradovic, Aleksandar Lj; Hwang, Sung Mi; Scarpa, Joseph; Hong, Sung Jun; Todorovic, Slobodan M; Jevtovic-Todorovic, Vesna

    2014-01-01

    We recently showed that streptozotocin (STZ) injections in rats lead to the development of painful peripheral diabetic neuropathy (PDN) accompanied by enhancement of CaV3.2 T-type calcium currents (T-currents) and hyperexcitability in dorsal root ganglion (DRG) neurons. Here we used the classical peripherally acting T-channel blocker mibefradil to examine the role of CaV3.2 T-channels as pharmacological targets for treatment of painful PDN. When administered intraperitoneally (i.p.), at clinically relevant doses, mibefradil effectively alleviated heat, cold and mechanical hypersensitivities in STZ-treated diabetic rats in a dose-dependent manner. We also found that CaV3.2 antisense (AS)-treated diabetic rats exhibit a significant decrease in painful PDN compared with mismatch antisense (MIS)-treated diabetic rats. Co-treatment with mibefradil (9 mg/kg i.p.) resulted in reversal of heat, cold and mechanical hypersensitivity in MIS-treated but not in AS-treated diabetic rats, suggesting that mibefradil and CaV3.2 AS share the same cellular target. Using patch-clamp recordings from acutely dissociated DRG neurons, we demonstrated that mibefradil similarly blocked T-currents in diabetic and healthy rats in a voltage-dependent manner by stabilizing inactive states of T-channels. We conclude that antihyperalgesic and antiallodynic effects of mibefradil in PDN are at least partly mediated by inhibition of CaV3.2 channels in peripheral nociceptors. Hence, peripherally acting voltage-dependent T-channel blockers could be very useful in the treatment of painful symptoms of PDN.

  15. CaV3.2 T-Type Calcium Channels in Peripheral Sensory Neurons Are Important for Mibefradil-Induced Reversal of Hyperalgesia and Allodynia in Rats with Painful Diabetic Neuropathy

    PubMed Central

    Obradovic, Aleksandar Lj.; Hwang, Sung Mi; Scarpa, Joseph; Hong, Sung Jun; Todorovic, Slobodan M.; Jevtovic-Todorovic, Vesna

    2014-01-01

    We recently showed that streptozotocin (STZ) injections in rats lead to the development of painful peripheral diabetic neuropathy (PDN) accompanied by enhancement of CaV3.2 T-type calcium currents (T-currents) and hyperexcitability in dorsal root ganglion (DRG) neurons. Here we used the classical peripherally acting T-channel blocker mibefradil to examine the role of CaV3.2 T-channels as pharmacological targets for treatment of painful PDN. When administered intraperitoneally (i.p.), at clinically relevant doses, mibefradil effectively alleviated heat, cold and mechanical hypersensitivities in STZ-treated diabetic rats in a dose-dependent manner. We also found that CaV3.2 antisense (AS)-treated diabetic rats exhibit a significant decrease in painful PDN compared with mismatch antisense (MIS)-treated diabetic rats. Co-treatment with mibefradil (9 mg/kg i.p.) resulted in reversal of heat, cold and mechanical hypersensitivity in MIS-treated but not in AS-treated diabetic rats, suggesting that mibefradil and CaV3.2 AS share the same cellular target. Using patch-clamp recordings from acutely dissociated DRG neurons, we demonstrated that mibefradil similarly blocked T-currents in diabetic and healthy rats in a voltage-dependent manner by stabilizing inactive states of T-channels. We conclude that antihyperalgesic and antiallodynic effects of mibefradil in PDN are at least partly mediated by inhibition of CaV3.2 channels in peripheral nociceptors. Hence, peripherally acting voltage-dependent T-channel blockers could be very useful in the treatment of painful symptoms of PDN. PMID:24705276

  16. Multilaminar networks of cortical neurons integrate common inputs from sensory thalamus.

    PubMed

    Morgenstern, Nicolás A; Bourg, Jacques; Petreanu, Leopoldo

    2016-08-01

    Neurons in the thalamorecipient layers of sensory cortices integrate thalamic and recurrent cortical input. Cortical neurons form fine-scale, functionally cotuned networks, but whether interconnected cortical neurons within a column process common thalamocortical inputs is unknown. We tested how local and thalamocortical connectivity relate to each other by analyzing cofluctuations of evoked responses in cortical neurons after photostimulation of thalamocortical axons. We found that connected pairs of pyramidal neurons in layer (L) 4 of mouse visual cortex share more inputs from the dorsal lateral geniculate nucleus than nonconnected pairs. Vertically aligned connected pairs of L4 and L2/3 neurons were also preferentially contacted by the same thalamocortical axons. Our results provide a circuit mechanism for the observed amplification of sensory responses by L4 circuits. They also show that sensory information is concurrently processed in L4 and L2/3 by columnar networks of interconnected neurons contacted by the same thalamocortical axons.

  17. Unimodal primary sensory cortices are directly connected by long-range horizontal projections in the rat sensory cortex

    PubMed Central

    Stehberg, Jimmy; Dang, Phat T.; Frostig, Ron D.

    2014-01-01

    Research based on functional imaging and neuronal recordings in the barrel cortex subdivision of primary somatosensory cortex (SI) of the adult rat has revealed novel aspects of structure-function relationships in this cortex. Specifically, it has demonstrated that single whisker stimulation evokes subthreshold neuronal activity that spreads symmetrically within gray matter from the appropriate barrel area, crosses cytoarchitectural borders of SI and reaches deeply into other unimodal primary cortices such as primary auditory (AI) and primary visual (VI). It was further demonstrated that this spread is supported by a spatially matching underlying diffuse network of border-crossing, long-range projections that could also reach deeply into AI and VI. Here we seek to determine whether such a network of border-crossing, long-range projections is unique to barrel cortex or characterizes also other primary, unimodal sensory cortices and therefore could directly connect them. Using anterograde (BDA) and retrograde (CTb) tract-tracing techniques, we demonstrate that such diffuse horizontal networks directly and mutually connect VI, AI and SI. These findings suggest that diffuse, border-crossing axonal projections connecting directly primary cortices are an important organizational motif common to all major primary sensory cortices in the rat. Potential implications of these findings for topics including cortical structure-function relationships, multisensory integration, functional imaging, and cortical parcellation are discussed. PMID:25309339

  18. Substance P-immunoreactive peripheral branches of sensory neurons innervate guinea pig sympathetic neurons

    PubMed Central

    Matthews, Margaret R.; Cuello, A. Claudio

    1982-01-01

    The presence of substance P-immunoreactive (SPI) varicose nerve networks and nerve fiber bundles in guinea pig prevertebral sympathetic ganglia has been confirmed by fluorescence immunohistochemistry. No SPI neurons have been found in sympathetic ganglia, including lumbar paravertebral ganglia. Peroxidase-antiperoxidase immunocytochemical methods have shown that SPI nerve terminal varicosities in the inferior mesenteric ganglion (IMG) form morphologically identifiable synapses on dendritic shafts. Cutting the intermesenteric nerve produces no obvious change in SP immunoreactivity in the IMG; cutting the lumbar splanchnic nerves produces nearly total depletion which becomes virtually complete if the two lesions are combined; SP immunoreactivity accumulates in the central ends of the lumbar splanchnic nerves and in the cranial end of the intermesenteric nerve. Cutting hypogastric nerves or colonic branches of the IMG leads to accumulation of SP immunoreactivity in their ganglionic stumps and to build-up (colonic nerve lesion) rather than depletion of SP immunoreactivity in the IMG. Capsaicin treatment leads to total loss of SP immunoreactivity from the prevertebral ganglia and dorsal root ganglia, severe depletion in laminae I and II and dorsolateral fasciculus of the spinal cord, and total loss from perivascular and paravascular networks of the ileum and mesentery, with sparing of the SP immunoreactivity of the enteric nerve plexuses. Capsaicin is thought to deplete sensory neurons selectively. Removal of the spinal cord below T7 without damage to the dorsal root ganglia leaves the intraganglionic SPI nerve networks and bundles intact. We conclude that these are derived from peripheral processes of sensory neurons and we propose that the SPI synapses in the IMG arise from collateral branches of these sensory peripheral processes. This implies a novel role for these processes, in forming intraganglionically in the prevertebral ganglia synapses which may take part in

  19. Sensory Neurons Arouse C. elegans Locomotion via Both Glutamate and Neuropeptide Release

    PubMed Central

    Chatzigeorgiou, Marios; Hu, Zhitao; Schafer, William R.; Kaplan, Joshua M.

    2015-01-01

    C. elegans undergoes periods of behavioral quiescence during larval molts (termed lethargus) and as adults. Little is known about the circuit mechanisms that establish these quiescent states. Lethargus and adult locomotion quiescence is dramatically reduced in mutants lacking the neuropeptide receptor NPR-1. Here, we show that the aroused locomotion of npr-1 mutants results from the exaggerated activity in multiple classes of sensory neurons, including nociceptive (ASH), touch sensitive (ALM and PLM), and stretch sensing (DVA) neurons. These sensory neurons accelerate locomotion via both neuropeptide and glutamate release. The relative contribution of these sensory neurons to arousal differs between larval molts and adults. Our results suggest that a broad network of sensory neurons dictates transitions between aroused and quiescent behavioral states. PMID:26154367

  20. touché is required for touch evoked generator potentials within vertebrate sensory neurons

    PubMed Central

    Low, Sean E.; Ryan, Joel; Sprague, Shawn M.; Hirata, Hiromi; Cui, Wilson W.; Zhou, Weibin; Hume, Richard I.; Kuwada, John Y.; Saint-Amant, Louis

    2010-01-01

    The process by which light-touch in vertebrates is transformed into an electrical response in cutaneous mechanosensitive neurons is a largely unresolved question. To address this question we undertook a forward genetic screen in zebrafish (Danio rerio) to identify mutants exhibiting abnormal touch-evoked behaviors, despite the presence of sensory neurons and peripheral neurites. One family, subsequently named touché, was found to harbor a recessive mutation which produced offspring that were unresponsive to light-touch, but responded to a variety of other sensory stimuli. The optogenetic activation of motor behaviors by touché mutant sensory neurons expressing ChannelRhodopsin-2 suggested that the synaptic output of sensory neurons was intact, consistent with a defect in sensory neuron activation. To explore sensory neuron activation we developed an in vivo preparation permitting the precise placement of a combined electrical and tactile stimulating probe upon eGFP positive peripheral neurites. In wild type larva electrical and tactile stimulation of peripheral neurites produced action potentials detectable within the cell body. In a subset of these sensory neurons an underlying generator potential could be observed in response to subthreshold tactile stimuli. A closer examination revealed that the amplitude of the generator potential was proportional to the stimulus amplitude. When assayed touché mutant sensory neurons also responded to electrical stimulation of peripheral neurites similar to wild type larvae, however tactile stimulation of these neurites failed to uncover a subset of sensory neurons possessing generator potentials. These findings suggest that touché is required for generator potentials, and that generator potentials underlie responsiveness to light-touch in zebrafish. PMID:20631165

  1. Excitatory interneurons dominate sensory processing in the spinal substantia gelatinosa of rat.

    PubMed

    Santos, Sónia F A; Rebelo, Sandra; Derkach, Victor A; Safronov, Boris V

    2007-05-15

    Substantia gelatinosa (SG, lamina II) is a spinal cord region where most unmyelinated primary afferents terminate and the central nociceptive processing begins. It is formed by several distinct groups of interneurons whose functional properties and synaptic connections are poorly understood, in part, because recordings from synaptically coupled pairs of SG neurons are quite challenging due to a very low probability of finding connected cells. Here, we describe an efficient method for identifying synaptically coupled interneurons in rat spinal cord slices and characterizing their excitatory or inhibitory function. Using tight-seal whole-cell recordings and a cell-attached stimulation technique, we routinely tested about 1500 SG interneurons, classifying 102 of them as monosynaptically connected to neurons in lamina I-III. Surprisingly, the vast majority of SG interneurons (n = 87) were excitatory and glutamatergic, while only 15 neurons were inhibitory. According to their intrinsic firing properties, these 102 SG neurons were also classified as tonic (n = 49), adapting (n = 17) or delayed-firing neurons (n = 36). All but two tonic neurons and all adapting neurons were excitatory interneurons. Of 36 delayed-firing neurons, 23 were excitatory and 13 were inhibitory. We conclude that sensory integration in the intrinsic SG neuronal network is dominated by excitatory interneurons. Such organization of neuronal circuitries in the spinal SG can be important for nociceptive encoding.

  2. Excitatory interneurons dominate sensory processing in the spinal substantia gelatinosa of rat

    PubMed Central

    Santos, Sónia F A; Rebelo, Sandra; Derkach, Victor A; Safronov, Boris V

    2007-01-01

    Substantia gelatinosa (SG, lamina II) is a spinal cord region where most unmyelinated primary afferents terminate and the central nociceptive processing begins. It is formed by several distinct groups of interneurons whose functional properties and synaptic connections are poorly understood, in part, because recordings from synaptically coupled pairs of SG neurons are quite challenging due to a very low probability of finding connected cells. Here, we describe an efficient method for identifying synaptically coupled interneurons in rat spinal cord slices and characterizing their excitatory or inhibitory function. Using tight-seal whole-cell recordings and a cell-attached stimulation technique, we routinely tested about 1500 SG interneurons, classifying 102 of them as monosynaptically connected to neurons in lamina I–III. Surprisingly, the vast majority of SG interneurons (n = 87) were excitatory and glutamatergic, while only 15 neurons were inhibitory. According to their intrinsic firing properties, these 102 SG neurons were also classified as tonic (n = 49), adapting (n = 17) or delayed-firing neurons (n = 36). All but two tonic neurons and all adapting neurons were excitatory interneurons. Of 36 delayed-firing neurons, 23 were excitatory and 13 were inhibitory. We conclude that sensory integration in the intrinsic SG neuronal network is dominated by excitatory interneurons. Such organization of neuronal circuitries in the spinal SG can be important for nociceptive encoding. PMID:17331995

  3. SCN2B in the Rat Trigeminal Ganglion and Trigeminal Sensory Nuclei.

    PubMed

    Shimada, Yusuke; Sato, Tadasu; Yajima, Takehiro; Fujita, Masatoshi; Hashimoto, Naoya; Shoji, Noriaki; Sasano, Takashi; Ichikawa, Hiroyuki

    2016-11-01

    The beta-2 subunit of the mammalian brain voltage-gated sodium channel (SCN2B) was examined in the rat trigeminal ganglion (TG) and trigeminal sensory nuclei. In the TG, 42.6 % of sensory neurons were immunoreactive (IR) for SCN2B. These neurons had various cell body sizes. In facial skins and oral mucosae, corpuscular nerve endings contained SCN2B-immunoreactivity. SCN2B-IR nerve fibers formed nerve plexuses beneath taste buds in the tongue and incisive papilla. However, SCN2B-IR free nerve endings were rare in cutaneous and mucosal epithelia. Tooth pulps, muscle spindles and major salivary glands were also innervated by SCN2B-IR nerve fibers. A double immunofluorescence method revealed that about 40 % of SCN2B-IR neurons exhibited calcitonin gene-related peptide (CGRP)-immunoreactivity. However, distributions of SCN2B- and CGRP-IR nerve fibers were mostly different in facial, oral and cranial structures. By retrograde tracing method, 60.4 and 85.3 % of TG neurons innervating the facial skin and tooth pulp, respectively, showed SCN2B-immunoreactivity. CGRP-immunoreactivity was co-localized by about 40 % of SCN2B-IR cutaneous and tooth pulp TG neurons. In trigeminal sensory nuclei of the brainstem, SCN2B-IR neuronal cell bodies were common in deep laminae of the subnucleus caudalis, and the subnuclei interpolaris and oralis. In the mesencephalic trigeminal tract nucleus, primary sensory neurons also exhibited SCN2B-immunoreactivity. In other regions of trigeminal sensory nuclei, SCN2B-IR cells were very infrequent. SCN2B-IR neuropil was detected in deep laminae of the subnucleus caudalis as well as in the subnuclei interpolaris, oralis and principalis. These findings suggest that SCN2B is expressed by various types of sensory neurons in the TG. There appears to be SCN2B-containing pathway in the TG and trigeminal sensory nuclei.

  4. Environmental enrichment causes a global potentiation of neuronal responses across stimulus complexity and lamina of sensory cortex

    PubMed Central

    Alwis, Dasuni S.; Rajan, Ramesh

    2013-01-01

    Enriched social and physical housing produces many molecular, anatomical, electrophysiological and behavior benefits even in adult animals. Much less is known of its effects on cortical electrophysiology, especially in how sensory cortex encodes the altered environment, and extant studies have generally been restricted to neurons in input laminae in sensory cortex. To extend the understanding of how an enriched environment alters the way in which cortex views the world, we investigated enrichment-induced changes in neuronal encoding of sensory stimuli across all laminae of the rat barrel cortex receiving input from the face whisker tactile system. Animals were housed in Enriched (n = 13) or Isolated housing (n = 13) conditions for 8 weeks before extracellular recordings were obtained from barrel cortex in response to simple whisker deflections and whisker motions modeling movements seen in awake animals undertaking a variety of different tasks. Enrichment resulted in increases in neuronal responses to all stimuli, ranging from those modeling exploratory behavior through to discrimination behaviors. These increases were seen throughout the cortex from supragranular layers through to input Layer 4 and for some stimuli, in infragranular Layer 5. The observed enrichment-induced effect is consistent with the postulate that enrichment causes shift in cortical excitatory/inhibitory balance, and we demonstrate this is greatest in supragranular layers. However, we also report that the effects are non-selective for stimulus parameters across a range of stimuli except for one modeling the likely use of whiskers by the rats in the enriched housing. PMID:23964199

  5. Synaptic inputs from stroke-injured brain to grafted human stem cell-derived neurons activated by sensory stimuli.

    PubMed

    Tornero, Daniel; Tsupykov, Oleg; Granmo, Marcus; Rodriguez, Cristina; Grønning-Hansen, Marita; Thelin, Jonas; Smozhanik, Ekaterina; Laterza, Cecilia; Wattananit, Somsak; Ge, Ruimin; Tatarishvili, Jemal; Grealish, Shane; Brüstle, Oliver; Skibo, Galina; Parmar, Malin; Schouenborg, Jens; Lindvall, Olle; Kokaia, Zaal

    2017-03-01

    Transplanted neurons derived from stem cells have been proposed to improve function in animal models of human disease by various mechanisms such as neuronal replacement. However, whether the grafted neurons receive functional synaptic inputs from the recipient's brain and integrate into host neural circuitry is unknown. Here we studied the synaptic inputs from the host brain to grafted cortical neurons derived from human induced pluripotent stem cells after transplantation into stroke-injured rat cerebral cortex. Using the rabies virus-based trans-synaptic tracing method and immunoelectron microscopy, we demonstrate that the grafted neurons receive direct synaptic inputs from neurons in different host brain areas located in a pattern similar to that of neurons projecting to the corresponding endogenous cortical neurons in the intact brain. Electrophysiological in vivo recordings from the cortical implants show that physiological sensory stimuli, i.e. cutaneous stimulation of nose and paw, can activate or inhibit spontaneous activity in grafted neurons, indicating that at least some of the afferent inputs are functional. In agreement, we find using patch-clamp recordings that a portion of grafted neurons respond to photostimulation of virally transfected, channelrhodopsin-2-expressing thalamo-cortical axons in acute brain slices. The present study demonstrates, for the first time, that the host brain regulates the activity of grafted neurons, providing strong evidence that transplanted human induced pluripotent stem cell-derived cortical neurons can become incorporated into injured cortical circuitry. Our findings support the idea that these neurons could contribute to functional recovery in stroke and other conditions causing neuronal loss in cerebral cortex. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  6. Femoral Artery Occlusion Increases Muscle Pressor Reflex and Expression of Hypoxia-Inducible Factor-1α in Sensory Neurons

    PubMed Central

    Gao, Wei; Li, Jianhua

    2013-01-01

    Hypoxia inducible factor-1 (HIF-1) has an important contribution to pathophysiological changes of homeostasis under conditions of oxygen deprivation as well as ischemia. We examined the effects of femoral artery occlusion on HIF-1α expression in sensory dorsal root ganglion (DRG) neurons of rats. Also, we examined cardiovascular responses to static muscle contraction following femoral occlusion. We hypothesized that hindlimb vascular insufficiency increases the levels of sensory nerves’ HIF-1α and augments autonomic responses induced by activation of muscle afferent nerves. In addition, we examined if the reflex cardiovascular responses were altered as HIF-1α was increased in the DRG neurons. Our data show that HIF-1α was significantly increased in the lumbar DRG neurons 6, 24 and 72 hours after femoral artery ligation as compared with sham control. Administration of dimethyloxalylglycine (DMOG), a stabilizer of HIF-α, significantly increased HIF-1α in the lumbar DRG neurons. Furthermore, femoral occlusion enhanced the reflex pressor response to muscle contraction; however, the response was not altered by injection of DMOG. Overall, our results indicate that 1) femoral artery occlusion increases HIF-1α levels of in DRG neurons and contraction-induced pressor response; and 2) an increase in HIF-1α of DRG neurons per se may not alter the muscle pressor reflex. PMID:25346936

  7. Generation of New Neurons in Dorsal Root Ganglia in Adult Rats after Peripheral Nerve Crush Injury

    PubMed Central

    2015-01-01

    The evidence of neurons generated ex novo in sensory ganglia of adult animals is still debated. In the present study, we investigated, using high resolution light microscopy and stereological analysis, the changes in the number of neurons in dorsal root ganglia after 30 days from a crush lesion of the rat brachial plexus terminal branches. Results showed, as expected, a relevant hypertrophy of dorsal root ganglion neurons. In addition, we reported, for the first time in the literature, that neuronal hypertrophy was accompanied by massive neuronal hyperplasia leading to a 42% increase of the number of primary sensory neurons. Moreover, ultrastructural analyses on sensory neurons showed that there was not a relevant neuronal loss as a consequence of the nerve injury. The evidence of BrdU-immunopositive neurons and neural progenitors labeled with Ki67, nanog, nestin, and sox-2 confirmed the stereological evidence of posttraumatic neurogenesis in dorsal root ganglia. Analysis of morphological changes following axonal damage in addition to immunofluorescence characterization of cell phenotype suggested that the neuronal precursors which give rise to the newly generated neurons could be represented by satellite glial cells that actively proliferate after the lesion and are able to differentiate toward the neuronal lineage. PMID:25722894

  8. Analysis of HSV Viral Reactivation in Explants of Sensory Neurons.

    PubMed

    Arbuckle, Jesse H; Turner, Anne-Marie W; Kristie, Thomas M

    2014-11-03

    As with all Herpesviruses, Herpes simplex virus (HSV) has both a lytic replication phase and a latency-reactivation cycle. During lytic replication, there is an ordered cascade of viral gene expression that leads to the synthesis of infectious viral progeny. In contrast, latency is characterized by the lack of significant lytic gene expression and the absence of infectious virus. Reactivation from latency is characterized by the re-entry of the virus into the lytic replication cycle and the production of recurrent disease. This unit describes the establishment of the mouse sensory neuron model of HSV-1 latency-reactivation as a useful in vivo system for the analysis of mechanisms involved in latency and reactivation. Assays including the determination of viral yields, immunohistochemical/immunofluorescent detection of viral antigens, and mRNA quantitation are used in experiments designed to investigate the network of cellular and viral proteins regulating HSV-1 lytic infection, latency, and reactivation. Copyright © 2014 John Wiley & Sons, Inc.

  9. Membrane stiffening by STOML3 facilitates mechanosensation in sensory neurons

    PubMed Central

    Qi, Yanmei; Andolfi, Laura; Frattini, Flavia; Mayer, Florian; Lazzarino, Marco; Hu, Jing

    2015-01-01

    Sensing force is crucial to maintain the viability of all living cells. Despite its fundamental importance, how force is sensed at the molecular level remains largely unknown. Here we show that stomatin-like protein-3 (STOML3) controls membrane mechanics by binding cholesterol and thus facilitates force transfer and tunes the sensitivity of mechano-gated channels, including Piezo channels. STOML3 is detected in cholesterol-rich lipid rafts. In mouse sensory neurons, depletion of cholesterol and deficiency of STOML3 similarly and interdependently attenuate mechanosensitivity while modulating membrane mechanics. In heterologous systems, intact STOML3 is required to maintain membrane mechanics to sensitize Piezo1 and Piezo2 channels. In C57BL/6N, but not STOML3−/− mice, tactile allodynia is attenuated by cholesterol depletion, suggesting that membrane stiffening by STOML3 is essential for mechanical sensitivity. Targeting the STOML3–cholesterol association might offer an alternative strategy for control of chronic pain. PMID:26443885

  10. Molecular Correlates of Cortical Network Modulation by Long-Term Sensory Experience in the Adult Rat Barrel Cortex

    ERIC Educational Resources Information Center

    Vallès, Astrid; Granic, Ivica; De Weerd, Peter; Martens, Gerard J. M.

    2014-01-01

    Modulation of cortical network connectivity is crucial for an adaptive response to experience. In the rat barrel cortex, long-term sensory stimulation induces cortical network modifications and neuronal response changes of which the molecular basis is unknown. Here, we show that long-term somatosensory stimulation by enriched environment…

  11. Molecular Correlates of Cortical Network Modulation by Long-Term Sensory Experience in the Adult Rat Barrel Cortex

    ERIC Educational Resources Information Center

    Vallès, Astrid; Granic, Ivica; De Weerd, Peter; Martens, Gerard J. M.

    2014-01-01

    Modulation of cortical network connectivity is crucial for an adaptive response to experience. In the rat barrel cortex, long-term sensory stimulation induces cortical network modifications and neuronal response changes of which the molecular basis is unknown. Here, we show that long-term somatosensory stimulation by enriched environment…

  12. Sensory responses in the medial prefrontal cortex of anesthetized rats. Implications for sensory processing.

    PubMed

    Martin-Cortecero, Jesus; Nuñez, Angel

    2016-12-17

    The medial prefrontal cortex (mPFC) plays a key role in higher functions such as memory and attention. In order to demonstrate sensory responses in the mPFC, we used electrophysiological recordings of urethane-anesthetized rats to record somatosensory-evoked potentials (SEPs) or auditory-evoked potentials (AEPs) elicited by whisker deflections and click stimulation, respectively. Contralateral whisker stimulation or auditory stimuli were also applied to study sensory interference in the mPFC. Interference with other sensory stimuli or recent stimulation history reduced whisker responses in the infralimbic and prelimbic cortices of the ventral mPFC. This effect could be mediated by activation of parvalbumin (PV) interneurons since the effect was blocked by the P/Q calcium channel antagonist ω-agatoxin. In contrast, sensory interference or the recent stimulation history was not detected by the dorsal mPFC or the primary somatosensory cortex. Results obtained from retrograde tracer injections in the dorsal and ventral regions of the mPFC indicated that somatosensory and auditory sensory inputs may arrive at the dorsal mPFC through secondary sensory cortical areas, and through the insular and temporal cortical areas. The ventral mPFC may receive sensory information through the strong anatomical connections between the dorsal and ventral mPFC areas. In conclusion, results suggest mPFC plays an important role in sensory processing, which may have important implications in attentional and memory processes.

  13. Prostaglandin potentiates 5-HT responses in stomach and ileum innervating visceral afferent sensory neurons.

    PubMed

    Kim, Sojin; Jin, Zhenhua; Lee, Goeun; Park, Yong Seek; Park, Cheung-Seog; Jin, Young-Ho

    2015-01-02

    Gastrointestinal disorder is a common symptom induced by diverse pathophysiological conditions that include food tolerance, chemotherapy, and irradiation for therapy. Prostaglandin E2 (PGE2) level increase was often reported during gastrointestinal disorder and prostaglandin synthetase inhibitors has been used for ameliorate the symptoms. Exogenous administration of PGE2 induces gastrointestinal disorder, however, the mechanism of action is not known. Therefore, we tested PGE2 effect on visceral afferent sensory neurons of the rat. Interestingly, PGE2 itself did not evoked any response but enhanced serotonin (5-HT)-evoked currents up to 167% of the control level. The augmented 5-HT responses were completely inhibited by a 5-HT type 3 receptor antagonist, ondansetron. The PGE2-induced potentiation were blocked by a selective E-prostanoid type 4 (EP4) receptors antagonist, L-161,982, but type 1 and 2 receptor antagonist AH6809 has no effect. A membrane permeable protein kinase A (PKA) inhibitor, KT5720 also inhibited PGE2 effects. PGE2 induced 5-HT current augmentation was observed on 15% and 21% of the stomach and ileum projecting neurons, respectively. Current results suggest a synergistic signaling in visceral afferent neurons underlying gastrointestinal disorder involving PGE2 potentiation of 5-HT currents. Our findings may open a possibility for screen a new type drugs with lower side effects than currently using steroidal prostaglandin synthetase inhibitors by selectively targeting EP4 receptor/PKA pathway without interrupt prostaglandin synthesis.

  14. Diabetic polyneuropathy, sensory neurons, nuclear structure and spliceosome alterations: a role for CWC22.

    PubMed

    Kobayashi, Masaki; Chandrasekhar, Ambika; Cheng, Chu; Martinez, Jose A; Ng, Hilarie; de la Hoz, Cristiane; Zochodne, Douglas W

    2017-03-01

    Unique deficits in the function of adult sensory neurons as part of their early neurodegeneration might account for progressive polyneuropathy during chronic diabetes mellitus. Here, we provide structural and functional evidence for aberrant pre-mRNA splicing in a chronic type 1 model of experimental diabetic polyneuropathy (DPN). Cajal bodies (CBs), unique nuclear substructures involved in RNA splicing, increased in number in diabetic sensory neurons, but their expected colocalization with survival motor neuron (SMN) proteins was reduced - a mislocalization described in motor neurons of spinal muscular atrophy. Small nuclear ribonucleoprotein particles (snRNPs), also participants in the spliceosome, had abnormal multiple nuclear foci unassociated with CBs, and their associated snRNAs were reduced. CWC22, a key spliceosome protein, was aberrantly upregulated in diabetic dorsal root ganglia (DRG), and impaired neuronal function. CWC22 attenuated sensory neuron plasticity, with knockdown in vitro enhancing their neurite outgrowth. Further, axonal delivery of CWC22 siRNA unilaterally to locally knock down the aberrant protein in diabetic nerves improved aspects of sensory function in diabetic mice. Collectively, our findings identify subtle but significant alterations in spliceosome structure and function, including dysregulated CBs and CWC22 overexpression, in diabetic sensory neurons that offer new ideas regarding diabetic sensory neurodegeneration in polyneuropathy.

  15. Diabetic polyneuropathy, sensory neurons, nuclear structure and spliceosome alterations: a role for CWC22

    PubMed Central

    Kobayashi, Masaki; Chandrasekhar, Ambika; Cheng, Chu; Martinez, Jose A.; Ng, Hilarie; de la Hoz, Cristiane

    2017-01-01

    ABSTRACT Unique deficits in the function of adult sensory neurons as part of their early neurodegeneration might account for progressive polyneuropathy during chronic diabetes mellitus. Here, we provide structural and functional evidence for aberrant pre-mRNA splicing in a chronic type 1 model of experimental diabetic polyneuropathy (DPN). Cajal bodies (CBs), unique nuclear substructures involved in RNA splicing, increased in number in diabetic sensory neurons, but their expected colocalization with survival motor neuron (SMN) proteins was reduced – a mislocalization described in motor neurons of spinal muscular atrophy. Small nuclear ribonucleoprotein particles (snRNPs), also participants in the spliceosome, had abnormal multiple nuclear foci unassociated with CBs, and their associated snRNAs were reduced. CWC22, a key spliceosome protein, was aberrantly upregulated in diabetic dorsal root ganglia (DRG), and impaired neuronal function. CWC22 attenuated sensory neuron plasticity, with knockdown in vitro enhancing their neurite outgrowth. Further, axonal delivery of CWC22 siRNA unilaterally to locally knock down the aberrant protein in diabetic nerves improved aspects of sensory function in diabetic mice. Collectively, our findings identify subtle but significant alterations in spliceosome structure and function, including dysregulated CBs and CWC22 overexpression, in diabetic sensory neurons that offer new ideas regarding diabetic sensory neurodegeneration in polyneuropathy. PMID:28250049

  16. Targeting dorsal root ganglia and primary sensory neurons for the treatment of chronic pain.

    PubMed

    Berta, Temugin; Qadri, Yawar; Tan, Ping-Heng; Ji, Ru-Rong

    2017-07-01

    Currently the treatment of chronic pain is inadequate and compromised by debilitating central nervous system side effects. Here we discuss new therapeutic strategies that target dorsal root ganglia (DRGs) in the peripheral nervous system for a better and safer treatment of chronic pain. Areas covered: The DRGs contain the cell bodies of primary sensory neurons including nociceptive neurons. After painful injuries, primary sensory neurons demonstrate maladaptive molecular changes in DRG cell bodies and in their axons. These changes result in hypersensitivity and hyperexcitability of sensory neurons (peripheral sensitization) and are crucial for the onset and maintenance of chronic pain. We discuss the following new strategies to target DRGs and primary sensory neurons as a means of alleviating chronic pain and minimizing side effects: inhibition of sensory neuron-expressing ion channels such as TRPA1, TRPV1, and Nav1.7, selective blockade of C- and Aβ-afferent fibers, gene therapy, and implantation of bone marrow stem cells. Expert opinion: These peripheral pharmacological treatments, as well as gene and cell therapies, aimed at DRG tissues and primary sensory neurons can offer better and safer treatments for inflammatory, neuropathic, cancer, and other chronic pain states.

  17. Reactive nucleolar and Cajal body responses to proteasome inhibition in sensory ganglion neurons.

    PubMed

    Palanca, Ana; Casafont, Iñigo; Berciano, María T; Lafarga, Miguel

    2014-06-01

    The dysfunction of the ubiquitin proteasome system has been related to a broad array of neurodegenerative disorders in which the accumulation of misfolded protein aggregates causes proteotoxicity. The ability of proteasome inhibitors to induce cell cycle arrest and apoptosis has emerged as a powerful strategy for cancer therapy. Bortezomib is a proteasome inhibitor used as an antineoplastic drug, although its neurotoxicity frequently causes a severe sensory peripheral neuropathy. In this study we used a rat model of bortezomib treatment to study the nucleolar and Cajal body responses to the proteasome inhibition in sensory ganglion neurons that are major targets of bortezomib-induced neurotoxicity. Treatment with bortezomib induced dose-dependent dissociation of protein synthesis machinery (chromatolysis) and nuclear retention of poly(A) RNA granules resulting in neuronal dysfunction. However, as a compensatory response to the proteotoxic stress, both nucleoli and Cajal bodies exhibited reactive changes. These include an increase in the number and size of nucleoli, strong nucleolar incorporation of the RNA precursor 5'-fluorouridine, and increased expression of both 45S rRNA and genes encoding nucleolar proteins UBF, fibrillarin and B23. Taken together, these findings appear to reflect the activation of the nucleolar transcription in response to proteotoxic stress Furthermore, the number of Cajal bodies, a parameter related to transcriptional activity, increases upon proteasome inhibition. We propose that nucleoli and Cajal bodies are important targets in the signaling pathways that are activated by the proteotoxic stress response to proteasome inhibition. The coordinating activity of these two organelles in the production of snRNA, snoRNA and rRNA may contribute to neuronal survival after proteasome inhibition. This article is part of a Special Issue entitled: Role of the Nucleolus in Human Disease.

  18. Sensory experience regulates cortical inhibition by inducing IGF1 in VIP neurons.

    PubMed

    Mardinly, A R; Spiegel, I; Patrizi, A; Centofante, E; Bazinet, J E; Tzeng, C P; Mandel-Brehm, C; Harmin, D A; Adesnik, H; Fagiolini, M; Greenberg, M E

    2016-03-17

    Inhibitory neurons regulate the adaptation of neural circuits to sensory experience, but the molecular mechanisms by which experience controls the connectivity between different types of inhibitory neuron to regulate cortical plasticity are largely unknown. Here we show that exposure of dark-housed mice to light induces a gene program in cortical vasoactive intestinal peptide (VIP)-expressing neurons that is markedly distinct from that induced in excitatory neurons and other subtypes of inhibitory neuron. We identify Igf1 as one of several activity-regulated genes that are specific to VIP neurons, and demonstrate that IGF1 functions cell-autonomously in VIP neurons to increase inhibitory synaptic input onto these neurons. Our findings further suggest that in cortical VIP neurons, experience-dependent gene transcription regulates visual acuity by activating the expression of IGF1, thus promoting the inhibition of disinhibitory neurons and affecting inhibition onto cortical pyramidal neurons.

  19. Anesthesia and brain sensory processing: impact on neuronal responses in a female songbird

    PubMed Central

    Karino, G.; George, I.; Loison, L.; Heyraud, C.; De Groof, G.; Hausberger, M.; Cousillas, H.

    2016-01-01

    Whether anesthesia impacts brain sensory processing is a highly debated and important issue. There is a general agreement that anesthesia tends to diminish neuronal activity, but its potential impact on neuronal “tuning” is still an open question. Here we show, based on electrophysiological recordings in the primary auditory area of a female songbird, that anesthesia induces neuronal responses towards biologically irrelevant sounds and prevents the seasonal neuronal tuning towards functionally relevant species-specific song elements. PMID:27966648

  20. Functional transplant of photoactivated adenylyl cyclase (PAC) into Aplysia sensory neurons.

    PubMed

    Nagahama, Tatsumi; Suzuki, Takeshi; Yoshikawa, Shinya; Iseki, Mineo

    2007-09-01

    In neural mechanisms of animal learning, intracellular cAMP has been known to play an important role. In the present experiments we attempted functional transplant of a photoactivated adenylyl cyclase (PAC) isolated from Euglena into Aplysia neurons, and explored whether PAC can produce cAMP in the neurons by light stimulation. Serotonergic modulation of mechanoafferent sensory neurons in Aplysia pleural ganglia has been reported to increase intracellular cAMP level and promotes synaptic transmission to motor neurons by increasing spike width of sensory neurons. When cAMP was directly injected into the sensory neurons, spike amplitude temporarily decreased while spike width temporarily increased. This effect was not substituted by injection of 5'AMP, and maintained longer in a bath solution containing IBMX, the phosphodiesterase inhibitor. We, therefore, explored these changes as indicators of appearance of the PAC function. PAC or the PAC expression vector (pNEX-PAC) was injected into cell bodies of sensory neurons. Spike amplitude decreased in both cases and spike width increased in the PAC injection when the neurons were stimulated with light, suggesting that the transplanted PAC works well in Aplysia neurons. These results indicate that we can control cAMP production in specific neurons with light by the functional transplant of PAC.

  1. Kv7.2 regulates the function of peripheral sensory neurons

    PubMed Central

    King, Chih H.; Lancaster, Eric; Salomon, Daniela; Peles, Elior; Scherer, Steven S.

    2014-01-01

    The Kv7 (KCNQ) family of voltage-gated K+ channels regulates cellular excitability. The functional role of Kv7.2 has been hampered by the lack of a viable Kcnq2-null animal model. In this study, we generated homozygous Kcnq2-null sensory neurons using the Cre-Lox system; in these mice, Kv7.2 expression is absent in the peripheral sensory neurons, whereas the expression of other molecular components of nodes (including Kv7.3), paranodes, and juxtaparanodes is not altered. The conditional Kcnq2-null animals exhibit normal motor performance, but have increased thermal hyperalgesia and mechanical allodynia. Whole cell patch recording technique demonstrates that Kcnq2-null sensory neurons have increased excitability and reduced spike frequency adaptation. Taken together, our results suggest that the loss of Kv7.2 activity increases the excitability of primary sensory neurons. PMID:24687876

  2. The boundary cap: a source of neural crest stem cells that generate multiple sensory neuron subtypes.

    PubMed

    Hjerling-Leffler, Jens; Marmigère, Frédéric; Heglind, Mikael; Cederberg, Anna; Koltzenburg, Martin; Enerbäck, Sven; Ernfors, Patrik

    2005-06-01

    The boundary cap (BC) is a transient neural crest-derived group of cells located at the dorsal root entry zone (DREZ) that have been shown to differentiate into sensory neurons and glia in vivo. We find that when placed in culture, BC cells self-renew, show multipotency in clonal cultures and express neural crest stem cell (NCSCs) markers. Unlike sciatic nerve NCSCs, the BC-NCSC (bNCSCs) generates sensory neurons upon differentiation. The bNCSCs constitute a common source of cells for functionally diverse types of neurons, as a single bNCSC can give rise to several types of nociceptive and thermoreceptive sensory neurons. Our data suggests that BC cells comprise a source of multipotent sensory specified stem cells that persist throughout embryogenesis.

  3. [The distribution of NADPH-diaphorase and neuronal no synthase in rat medulla oblongata nuclei].

    PubMed

    Chertok, V M; Kotsuba, A E

    2013-01-01

    The distribution of nitroxide ergic neurons in the medulla oblongata nuclei in Wistar rats (n = 8) was studied histochemically (NADPH-diaphorase) and using immunohistochemistry with an antiserum against neuronal form of nitric oxide synthase (nNOS). NADPH-diaphorase activity was found in large and small neurons of the sensory, autonomic and motor nuclei. The latter were especially rich in the cells demonstrating the activity of the enzyme. Unlike NADPH-diaphorase, nNOS in the corresponding nuclei was always detected in the fewer number of neurons, predominantly of small sizes. The sensory nuclei (nucleus of solitary tract, reticular parvocellular and lateral nuclei, spinal nucleus of the trigeminal nerve) contained 1.5-3 times more nNOS neurons than in motor nuclei. In some nuclei (nucleus ambiguus, hypoglossal nerve nucleus), containing numerous NADPH-diaphorase-positive neurons, immunoreactive cells were particularly rare.

  4. The dusp1 Immediate Early Gene is Regulated by Natural Stimuli Predominantly in Sensory Input Neurons

    PubMed Central

    Horita, Haruhito; Wada, Kazuhiro; Rivas, Miriam V.; Hara, Erina; Jarvis, Erich D.

    2010-01-01

    Many immediate early genes (IEGs) have activity-dependent induction in a subset of brain subdivisions or neuron types. However, none have been reported yet with regulation specific to thalamic-recipient sensory neurons of the telencephalon or in the thalamic sensory input neurons themselves. Here, we report the first such gene, dual specificity phosphatase 1 (dusp1). Dusp1 is an inactivator of mitogen-activated protein kinase (MAPK), and MAPK activates expression of egr1, one of the most commonly studied IEGs, as determined in cultured cells. We found that in the brain of naturally behaving songbirds and other avian species, hearing song, seeing visual stimuli, or performing motor behavior caused high dusp1 upregulation, respectively, in auditory, visual, and somatosensory input cell populations of the thalamus and thalamic-recipient sensory neurons of the telencephalic pallium, whereas high egr1 upregulation occurred only in subsequently connected secondary and tertiary sensory neuronal populations of these same pathways. Motor behavior did not induce high levels of dusp1 expression in the motor-associated areas adjacent to song nuclei, where egr1 is upregulated in response to movement. Our analysis of dusp1 expression in mouse brain suggests similar regulation in the sensory input neurons of the thalamus and thalamic-recipient layer IV and VI neurons of the cortex. These findings suggest that dusp1 has specialized regulation to sensory input neurons of the thalamus and telencephalon; they further suggest that this regulation may serve to attenuate stimulus-induced expression of egr1 and other IEGs, leading to unique molecular properties of forebrain sensory input neurons. PMID:20506480

  5. The critical period for peripheral specification of dorsal root ganglion neurons is related to the period of sensory neurogenesis

    SciTech Connect

    Smith, C.L. )

    1990-12-01

    Thoracic sensory neurons in bullfrog tadpoles can be induced to form connections typical of brachial sensory neurons by transplanting thoracic ganglia to the branchial level at stages when some thoracic sensory neurons already have formed connections. In order to find out how many postmitotic sensory neurons survive transplantation, ({sup 3}H)thymidine was administered to tadpoles in which thoracic ganglia were transplanted to the brachial level unilaterally at stages VII to IX. Between 16 and 37% of the neurons in transplanted ganglia were unlabeled, as compared to 46 to 60% in unoperated ganglia. Transplanted ganglia contained fewer unlabeled neurons than corresponding unoperated ganglia, indicating that transplantation caused degeneration of postmitotic neurons. Therefore, a large fraction of the neurons that formed connections typical of brachial sensory neurons probably differentiated while they were at the brachial level.

  6. Human Induced Pluripotent Cell-Derived Sensory Neurons for Fate Commitment of Bone Marrow-Derived Schwann Cells: Implications for Remyelination Therapy.

    PubMed

    Cai, Sa; Han, Lei; Ao, Qiang; Chan, Ying-Shing; Shum, Daisy Kwok-Yan

    2016-09-14

    : Strategies that exploit induced pluripotent stem cells (iPSCs) to derive neurons have relied on cocktails of cytokines and growth factors to bias cell-signaling events in the course of fate choice. These are often costly and inefficient, involving multiple steps. In this study, we took an alternative approach and selected 5 small-molecule inhibitors of key signaling pathways in an 8-day program to induce differentiation of human iPSCs into sensory neurons, reaching ≥80% yield in terms of marker proteins. Continuing culture in maintenance medium resulted in neuronal networks immunopositive for synaptic vesicle markers and vesicular glutamate transporters suggestive of excitatory neurotransmission. Subpopulations of the derived neurons were electrically excitable, showing tetrodotoxin-sensitive action potentials in patch-clamp experiments. Coculture of the derived neurons with rat Schwann cells under myelinating conditions resulted in upregulated levels of neuronal neuregulin 1 type III in conjunction with the phosphorylated receptors ErbB2 and ErbB3, consistent with amenability of the neuritic network to myelination. As surrogates of embryonic dorsal root ganglia neurons, the derived sensory neurons provided contact-dependent cues to commit bone marrow-derived Schwann cell-like cells to the Schwann cell fate. Our rapid and efficient induction protocol promises not only controlled differentiation of human iPSCs into sensory neurons, but also utility in the translation to a protocol whereby human bone marrow-derived Schwann cells become available for autologous transplantation and remyelination therapy.

  7. Bursts of recurrent excitation in the activation of intrinsic sensory neurons of the intestine.

    PubMed

    Bertrand, P P

    2004-01-01

    Sensory neurons intrinsic to the wall of the intestine receive input from stimuli in the lumen. These stimuli interact with the mucosal epithelium causing release of sensory mediators that depolarize the sensory nerve terminals. The depolarization and the subsequent pattern of action potential (AP) discharge controls the type and magnitude of the reflex evoked. The characteristics of this AP discharge were investigated in 60 intrinsic sensory neurons from the myenteric plexus of the guinea-pig ileum. Intracellular electrophysiological recordings were made from neurons near intact mucosa during electrical stimulation of the mucosa and/or neuronal soma. Most neurons (87%) responded to mucosal stimulation with a burst of 3.8+/-0.3 APs (average instantaneous frequency, fINT 39+/-4 Hz). In 38%, a somatically evoked AP triggered a similar burst of 2.9+/-0.3 APs (fINT 52+/-6 Hz) while in 50% of neurons, there was ongoing spontaneous bursting (3.8+/-0.2 APs, fINT 48+/-6 Hz). APs in all of these bursts had an inflection on the rising phase and they persisted during somatic hyperpolarization indicating they were generated in a distal process rather than the soma. Collision experiments confirmed this and suggested that bursts originated near the mucosal sensory nerve terminals. A reduction in membrane excitability reduced the number of APs in a burst suggesting a brief depolarizing event, such as a voltage- or ligand-gated ion channel, was responsible. Bursting behavior in the intrinsic sensory neurons is common for mucosal stimuli and may involve a novel transmitter acting at the sensory nerve terminal. Further, some bursting involves positive feedback between the nerve terminals and other elements in the epithelium. This is a novel and potentially important component of intestinal sensory transduction.

  8. Communication between neuronal somata and satellite glial cells in sensory ganglia.

    PubMed

    Huang, Li-Yen M; Gu, Yanping; Chen, Yong

    2013-10-01

    Studies of the structural organization and functions of the cell body of a neuron (soma) and its surrounding satellite glial cells (SGCs) in sensory ganglia have led to the realization that SGCs actively participate in the information processing of sensory signals from afferent terminals to the spinal cord. SGCs use a variety ways to communicate with each other and with their enwrapped soma. Changes in this communication under injurious conditions often lead to abnormal pain conditions. "What are the mechanisms underlying the neuronal soma and SGC communication in sensory ganglia?" and "how do tissue or nerve injuries affect the communication?" are the main questions addressed in this review.

  9. Dose-Dependent Differential Effect of Neurotrophic Factors on In Vitro and In Vivo Regeneration of Motor and Sensory Neurons

    PubMed Central

    Santos, Daniel; Gonzalez-Perez, Francisco; Navarro, Xavier

    2016-01-01

    Although peripheral axons can regenerate after nerve transection and repair, functional recovery is usually poor due to inaccurate reinnervation. Neurotrophic factors promote directional guidance to regenerating axons and their selective application may help to improve functional recovery. Hence, we have characterized in organotypic cultures of spinal cord and dorsal root ganglia the effect of GDNF, FGF-2, NGF, NT-3, and BDNF at different concentrations on motor and sensory neurite outgrowth. In vitro results show that GDNF and FGF-2 enhanced both motor and sensory neurite outgrowth, NGF and NT-3 were the most selective to enhance sensory neurite outgrowth, and high doses of BDNF selectively enhanced motor neurite outgrowth. Then, NGF, NT-3, and BDNF (as the most selective factors) were delivered in a collagen matrix within a silicone tube to repair the severed sciatic nerve of rats. Quantification of Fluorogold retrolabeled neurons showed that NGF and NT-3 did not show preferential effect on sensory regeneration whereas BDNF preferentially promoted motor axons regeneration. Therefore, the selective effects of NGF and NT-3 shown in vitro are lost when they are applied in vivo, but a high dose of BDNF is able to selectively enhance motor neuron regeneration both in vitro and in vivo. PMID:27867665

  10. Dose-Dependent Differential Effect of Neurotrophic Factors on In Vitro and In Vivo Regeneration of Motor and Sensory Neurons.

    PubMed

    Santos, Daniel; Gonzalez-Perez, Francisco; Navarro, Xavier; Del Valle, Jaume

    2016-01-01

    Although peripheral axons can regenerate after nerve transection and repair, functional recovery is usually poor due to inaccurate reinnervation. Neurotrophic factors promote directional guidance to regenerating axons and their selective application may help to improve functional recovery. Hence, we have characterized in organotypic cultures of spinal cord and dorsal root ganglia the effect of GDNF, FGF-2, NGF, NT-3, and BDNF at different concentrations on motor and sensory neurite outgrowth. In vitro results show that GDNF and FGF-2 enhanced both motor and sensory neurite outgrowth, NGF and NT-3 were the most selective to enhance sensory neurite outgrowth, and high doses of BDNF selectively enhanced motor neurite outgrowth. Then, NGF, NT-3, and BDNF (as the most selective factors) were delivered in a collagen matrix within a silicone tube to repair the severed sciatic nerve of rats. Quantification of Fluorogold retrolabeled neurons showed that NGF and NT-3 did not show preferential effect on sensory regeneration whereas BDNF preferentially promoted motor axons regeneration. Therefore, the selective effects of NGF and NT-3 shown in vitro are lost when they are applied in vivo, but a high dose of BDNF is able to selectively enhance motor neuron regeneration both in vitro and in vivo.

  11. Dendritic spine dysgenesis in superficial dorsal horn sensory neurons after spinal cord injury.

    PubMed

    Cao, Xiaoyu C; Pappalardo, Laura W; Waxman, Stephen G; Tan, Andrew M

    2017-01-01

    Neuropathic pain is a major complication of spinal cord injury, and despite aggressive efforts, this type of pain is refractory to available clinical treatment. Our previous work has demonstrated a structure-function link between dendritic spine dysgenesis on nociceptive sensory neurons in the intermediate zone, laminae IV/V, and chronic pain in central nervous system and peripheral nervous system injury models of neuropathic pain. To extend these findings, we performed a follow-up structural analysis to assess whether dendritic spine remodeling occurs on superficial dorsal horn neurons located in lamina II after spinal cord injury. Lamina II neurons are responsible for relaying deep, delocalized, often thermally associated pain commonly experienced in spinal cord injury pathologies. We analyzed dendritic spine morphometry and localization in tissue obtained from adult rats exhibiting neuropathic pain one-month following spinal cord injury. Although the total density of dendritic spines on lamina II neurons did not change after spinal cord injury, we observed an inverse relationship between the densities of thin- and mushroom-shaped spines: thin-spine density decreased while mushroom-spine density increased. These structural changes were specifically noted along dendritic branches within 150 µm from the soma, suggesting a possible adverse contribution to nociceptive circuit function. Intrathecal treatment with NSC23766, a Rac1-GTPase inhibitor, significantly reduced spinal cord injury-induced changes in both thin- and mushroom-shaped dendritic spines. Overall, these observations demonstrate that dendritic spine remodeling occurs in lamina II, regulated in part by the Rac1-signaling pathway, and suggests that structural abnormalities in this spinal cord region may also contribute to abnormal nociception after spinal cord injury.

  12. Dendritic spine dysgenesis in superficial dorsal horn sensory neurons after spinal cord injury

    PubMed Central

    Cao, Xiaoyu C; Pappalardo, Laura W; Waxman, Stephen G

    2017-01-01

    Neuropathic pain is a major complication of spinal cord injury, and despite aggressive efforts, this type of pain is refractory to available clinical treatment. Our previous work has demonstrated a structure–function link between dendritic spine dysgenesis on nociceptive sensory neurons in the intermediate zone, laminae IV/V, and chronic pain in central nervous system and peripheral nervous system injury models of neuropathic pain. To extend these findings, we performed a follow-up structural analysis to assess whether dendritic spine remodeling occurs on superficial dorsal horn neurons located in lamina II after spinal cord injury. Lamina II neurons are responsible for relaying deep, delocalized, often thermally associated pain commonly experienced in spinal cord injury pathologies. We analyzed dendritic spine morphometry and localization in tissue obtained from adult rats exhibiting neuropathic pain one-month following spinal cord injury. Although the total density of dendritic spines on lamina II neurons did not change after spinal cord injury, we observed an inverse relationship between the densities of thin- and mushroom-shaped spines: thin-spine density decreased while mushroom-spine density increased. These structural changes were specifically noted along dendritic branches within 150 µm from the soma, suggesting a possible adverse contribution to nociceptive circuit function. Intrathecal treatment with NSC23766, a Rac1-GTPase inhibitor, significantly reduced spinal cord injury-induced changes in both thin- and mushroom-shaped dendritic spines. Overall, these observations demonstrate that dendritic spine remodeling occurs in lamina II, regulated in part by the Rac1-signaling pathway, and suggests that structural abnormalities in this spinal cord region may also contribute to abnormal nociception after spinal cord injury. PMID:28326929

  13. O-GlcNAc Transferase Is Essential for Sensory Neuron Survival and Maintenance.

    PubMed

    Su, Cathy; Schwarz, Thomas L

    2017-02-22

    O-GlcNAc transferase (OGT) regulates a wide range of cellular processes through the addition of the O-GlcNAc sugar moiety to thousands of protein substrates. Because nutrient availability affects the activity of OGT, its role has been broadly studied in metabolic tissues. OGT is enriched in the nervous system, but little is known about its importance in basic neuronal processes in vivo Here, we show that OGT is essential for sensory neuron survival and maintenance in mice. Sensory neuron-specific knock-out of OGT results in behavioral hyposensitivity to thermal and mechanical stimuli accompanied by decreased epidermal innervation and cell-body loss in the dorsal root ganglia. These effects are observed early in postnatal development and progress as animals age. Cultured sensory neurons lacking OGT also exhibit decreased axonal outgrowth. The effects on neuronal health in vivo are not solely due to disruption of developmental processes, because inducing OGT knock-out in the sensory neurons of adult mice results in a similar decrease in nerve fiber endings and cell bodies. Significant nerve-ending loss occurs before a decrease in cell bodies; this phenotype is indicative of axonal dieback that progresses to neuronal death. Our findings demonstrate that OGT is important in regulating axonal maintenance in the periphery and the overall health and survival of sensory neurons.SIGNIFICANCE STATEMENT We show the importance of O-GlcNAc transferase (OGT) for sensory neuron health and survival in vivo This study is the first to find that loss of OGT results in neuronal cell death. Moreover, it suggests that aberrant O-GlcNAc signaling can contribute to the development of neuropathy. The sensory neurons lie outside of the blood-brain barrier and therefore, compared to central neurons, may have a greater need for mechanisms of metabolic sensing and compensation. Peripheral sensory neurons in particular are subject to degeneration in diabetes. Our findings provide a foundation

  14. Peptidergic CGRPα primary sensory neurons encode heat and itch and tonically suppress sensitivity to cold.

    PubMed

    McCoy, Eric S; Taylor-Blake, Bonnie; Street, Sarah E; Pribisko, Alaine L; Zheng, Jihong; Zylka, Mark J

    2013-04-10

    Calcitonin gene-related peptide (CGRP) is a classic molecular marker of peptidergic primary somatosensory neurons. Despite years of research, it is unknown whether these neurons are required to sense pain or other sensory stimuli. Here, we found that genetic ablation of CGRPα-expressing sensory neurons reduced sensitivity to noxious heat, capsaicin, and itch (histamine and chloroquine) and impaired thermoregulation but did not impair mechanosensation or β-alanine itch-stimuli associated with nonpeptidergic sensory neurons. Unexpectedly, ablation enhanced behavioral responses to cold stimuli and cold mimetics without altering peripheral nerve responses to cooling. Mechanistically, ablation reduced tonic and evoked activity in postsynaptic spinal neurons associated with TRPV1/heat, while profoundly increasing tonic and evoked activity in spinal neurons associated with TRPM8/cold. Our data reveal that CGRPα sensory neurons encode heat and itch and tonically cross-inhibit cold-responsive spinal neurons. Disruption of this crosstalk unmasks cold hypersensitivity, with mechanistic implications for neuropathic pain and temperature perception.

  15. Peptidergic CGRPα primary sensory neurons encode heat and itch and tonically suppress sensitivity to cold

    PubMed Central

    McCoy, Eric S.; Taylor-Blake, Bonnie; Street, Sarah E.; Pribisko, Alaine L.; Zheng, Jihong; Zylka, Mark J.

    2013-01-01

    SUMMARY Calcitonin gene-related peptide (CGRP) is a classic molecular marker of peptidergic primary somatosensory neurons. Despite years of research, it is unknown if these neurons are required to sense pain or other sensory stimuli. Here, we found that genetic ablation of CGRPα-expressing sensory neurons reduced sensitivity to noxious heat, capsaicin and itch (histamine and chloroquine) and impaired thermoregulation but did not impair mechanosensation or β-alanine itch—stimuli associated with nonpeptidergic sensory neurons. Unexpectedly, ablation enhanced behavioral responses to cold stimuli and cold mimetics without altering peripheral nerve responses to cooling. Mechanistically, ablation reduced tonic and evoked activity in postsynaptic spinal neurons associated with TRPV1/heat, while profoundly increasing tonic and evoked activity in spinal neurons associated with TRPM8/cold. Our data reveal that CGRPα sensory neurons encode heat and itch and tonically cross-inhibit cold-responsive spinal neurons. Disruption of this crosstalk unmasks cold hypersensitivity, with mechanistic implications for neuropathic pain and temperature perception. PMID:23523592

  16. Differences in electrophysiological properties of functionally identified nociceptive sensory neurons in an animal model of cancer-induced bone pain

    PubMed Central

    Zhu, Yong Fang; Ungard, Robert; Seidlitz, Eric; Zacal, Natalie; Huizinga, Jan; Henry, James L

    2016-01-01

    Background Bone cancer pain is often severe, yet little is known about mechanisms generating this type of chronic pain. While previous studies have identified functional alterations in peripheral sensory neurons that correlate with bone tumours, none has provided direct evidence correlating behavioural nociceptive responses with properties of sensory neurons in an intact bone cancer model. Results In a rat model of prostate cancer-induced bone pain, we confirmed tactile hypersensitivity using the von Frey test. Subsequently, we recorded intracellularly from dorsal root ganglion neurons in vivo in anesthetized animals. Neurons remained connected to their peripheral receptive terminals and were classified on the basis of action potential properties, responses to dorsal root stimulation, and to mechanical stimulation of the respective peripheral receptive fields. Neurons included C-, Aδ-, and Aβ-fibre nociceptors, identified by their expression of substance P. We suggest that bone tumour may induce phenotypic changes in peripheral nociceptors and that these could contribute to bone cancer pain. Conclusions This work represents a significant technical and conceptual advance in the study of peripheral nociceptor functions in the development of cancer-induced bone pain. This is the first study to report that changes in sensitivity and excitability of dorsal root ganglion primary afferents directly correspond to mechanical allodynia and hyperalgesia behaviours following prostate cancer cell injection into the femur of rats. Furthermore, our unique combination of techniques has allowed us to follow, in a single neuron, mechanical pain-related behaviours, electrophysiological changes in action potential properties, and dorsal root substance P expression. These data provide a more complete understanding of this unique pain state at the cellular level that may allow for future development of mechanism-based treatments for cancer-induced bone pain. PMID:27030711

  17. State-dependent sculpting of olfactory sensory neurons is attributed to sensory enrichment, odor deprivation, and aging.

    PubMed

    Cavallin, Melissa Ann; Powell, Katelyn; Biju, K C; Fadool, Debra Ann

    2010-10-11

    Gene-targeted deletion of the predominant Shaker potassium channel, Kv1.3, in the mitral cells of the olfactory bulb, decreases the number of presynaptic, odorant receptor (OR)-identified olfactory sensory neurons (OSNs) in the main olfactory epithelium (MOE) and alters the nature of their postsynaptic connections to mitral cell targets. The current study examined whether OSN density was state-dependent by examining the impact of (1) odor enrichment, (2) sensory deprivation, and (3) aging upon the number of P2- or M72-expressing neurons. Histological approaches were used to quantify the number of OSNs across entire epithelia for wildtype (WT) vs. Kv1.3-null (KO) mice bred onto an ORtauLacZ reporter background. Following either odor enrichment or early unilateral naris-occlusion, the number of M72-expressing OSNs was significantly decreased in WT mice, but was unchanged in KO animals. Following naris-occlusion, the number of P2-expressing OSNs was decreased regardless of genotype. Animals that were reared to 2 years of age demonstrated loss of both P2- and M72-expressing OSNs in WT mice and a concomitant loss of only M72-expressing neurons in KO mice. These findings suggest that voltage-gated activity of the mitral cells is important for OSN plasticity, and can prevent neuronal loss via sensory- and OR-dependent mechanisms.

  18. Peripheral multidendritic sensory neurons are necessary for rhythmic locomotion behavior in Drosophila larvae

    PubMed Central

    Song, Wei; Onishi, Maika; Jan, Lily Yeh; Jan, Yuh Nung

    2007-01-01

    From breathing to walking, rhythmic movements encompass physiological processes important across the entire animal kingdom. It is thought by many that the generation of rhythmic behavior is operated by a central pattern generator (CPG) and does not require peripheral sensory input. Sensory feedback is, however, required to modify or coordinate the motor activity in response to the circumstances of actual movement. In contrast to this notion, we report here that sensory input is necessary for the generation of Drosophila larval locomotion, a form of rhythmic behavior. Blockage of all peripheral sensory inputs resulted in cessation of larval crawling. By conditionally silencing various subsets of larval peripheral sensory neurons, we identified the multiple dendritic (MD) neurons as the neurons essential for the generation of rhythmic peristaltic locomotion. By recording the locomotive motor activities, we further demonstrate that removal of MD neuron input disrupted rhythmic motor firing pattern in a way that prolonged the stereotyped segmental motor firing duration and prevented the propagation of posterior to anterior segmental motor firing. These findings reveal that MD sensory neuron input is a necessary component in the neural circuitry that generates larval locomotion. PMID:17360325

  19. The evolutionarily conserved transcription factor PRDM12 controls sensory neuron development and pain perception.

    PubMed

    Nagy, Vanja; Cole, Tiffany; Van Campenhout, Claude; Khoung, Thang M; Leung, Calvin; Vermeiren, Simon; Novatchkova, Maria; Wenzel, Daniel; Cikes, Domagoj; Polyansky, Anton A; Kozieradzki, Ivona; Meixner, Arabella; Bellefroid, Eric J; Neely, G Gregory; Penninger, Josef M

    2015-01-01

    PR homology domain-containing member 12 (PRDM12) belongs to a family of conserved transcription factors implicated in cell fate decisions. Here we show that PRDM12 is a key regulator of sensory neuronal specification in Xenopus. Modeling of human PRDM12 mutations that cause hereditary sensory and autonomic neuropathy (HSAN) revealed remarkable conservation of the mutated residues in evolution. Expression of wild-type human PRDM12 in Xenopus induced the expression of sensory neuronal markers, which was reduced using various human PRDM12 mutants. In Drosophila, we identified Hamlet as the functional PRDM12 homolog that controls nociceptive behavior in sensory neurons. Furthermore, expression analysis of human patient fibroblasts with PRDM12 mutations uncovered possible downstream target genes. Knockdown of several of these target genes including thyrotropin-releasing hormone degrading enzyme (TRHDE) in Drosophila sensory neurons resulted in altered cellular morphology and impaired nociception. These data show that PRDM12 and its functional fly homolog Hamlet are evolutionary conserved master regulators of sensory neuronal specification and play a critical role in pain perception. Our data also uncover novel pathways in multiple species that regulate evolutionary conserved nociception.

  20. Activation and desensitization of TRPV1 channels in sensory neurons by the PPARα agonist palmitoylethanolamide

    PubMed Central

    Ambrosino, Paolo; Soldovieri, Maria Virginia; Russo, Claudio; Taglialatela, Maurizio

    2013-01-01

    Background and Purpose Palmitoylethanolamide (PEA) is an endogenous fatty acid amide displaying anti-inflammatory and analgesic actions. To investigate the molecular mechanism responsible for these effects, the ability of PEA and of pain-inducing stimuli such as capsaicin (CAP) or bradykinin (BK) to influence intracellular calcium concentrations ([Ca2+]i) in peripheral sensory neurons, has been assessed in the present study. The potential involvement of the transcription factor PPARα and of TRPV1 channels in PEA-induced effects was also studied. Experimental Approach [Ca2+]i was evaluated by single-cell microfluorimetry in differentiated F11 cells. Activation of TRPV1 channels was assessed by imaging and patch-clamp techniques in CHO cells transiently-transfected with rat TRPV1 cDNA. Key Results In F11 cells, PEA (1–30 μM) dose-dependently increased [Ca2+]i. The TRPV1 antagonists capsazepine (1 μM) and SB-366791 (1 μM), as well as the PPARα antagonist GW-6471 (10 μM), inhibited PEA-induced [Ca2+]i increase; blockers of cannabinoid receptors were ineffective. PEA activated TRPV1 channels heterologously expressed in CHO cells; this effect appeared to be mediated at least in part by PPARα. When compared with CAP, PEA showed similar potency and lower efficacy, and caused stronger TRPV1 currents desensitization. Sub-effective PEA concentrations, closer to those found in vivo, counteracted CAP- and BK-induced [Ca2+]i transients, as well as CAP-induced TRPV1 activation. Conclusions and Implications Activation of PPARα and TRPV1 channels, rather than of cannabinoid receptors, largely mediate PEA-induced [Ca2+]i transients in sensory neurons. Differential TRPV1 activation and desensitization by CAP and PEA might contribute to their distinct pharmacological profile, possibly translating into potentially relevant clinical differences. PMID:23083124

  1. Regulation of motor patterns by the central spike-initiation zone of a sensory neuron.

    PubMed

    Daur, Nelly; Nadim, Farzan; Stein, Wolfgang

    2009-09-01

    Sensory feedback from muscles and peripheral sensors acts to initiate, tune or reshape motor activity according to the state of the body. Yet, sensory neurons often show low levels of activity even in the absence of sensory input. Here we examine the functional role of spontaneous low-frequency activity of such a sensory neuron. The anterior gastric receptor (AGR) is a muscle-tendon organ in the crab stomatogastric nervous system whose phasic activity shapes the well-characterized gastric mill (chewing) and pyloric (filtering) motor rhythms. Phasic activity is driven by a spike-initiation zone near the innervated muscle. We demonstrate that AGR possesses a second spike-initiation zone, which is located spatially distant from the innervated muscle in a central section of the axon. This initiation zone generates tonic activity and is responsible for the spontaneous activity of AGR in vivo, but does not code sensory information. Rather, it is sensitive to the neuromodulator octopamine. A computational model indicates that the activity at this initiation zone is not caused by excitatory input from another neuron, but generated intrinsically. This tonic activity is functionally relevant, because it modifies the activity state of the gastric mill motor circuit and changes the pyloric rhythm. The sensory function of AGR is not impaired as phasic activity suppresses spiking at the central initiation zone. Our results thus demonstrate that sensory neurons are not mere reporters of sensory signals. Neuromodulators can elicit non-sensory coding activity in these neurons that shapes the state of the motor system.

  2. Receptive properties of mouse sensory neurons innervating hairy skin.

    PubMed

    Koltzenburg, M; Stucky, C L; Lewin, G R

    1997-10-01

    high stimulus intensities; these units were termed RA/SA units. We conclude that all types of cutaneous afferent fibers are already committed to their phenotype 2 wk after birth but undergo some maturation over the following weeks. This preparation has great potential for the study of transgenic mice with targeted mutations of genes that code factors that are involved in the specification of sensory neuron phenotypes.

  3. Polysensory response characteristics of dorsal root ganglion neurones that may serve sensory functions during myocardial ischaemia.

    PubMed

    Huang, M H; Horackova, M; Negoescu, R M; Wolf, S; Armour, J A

    1996-09-01

    To determine the response characteristics of dorsal root ganglion neurones that may serve sensory functions during myocardial ischaemia. Extracellular recordings were made from 54 spontaneously active and 5 normally quiescent dorsal root ganglion neurones (T2-T5) in 22 anaesthetized open-chest dogs under control conditions and during epicardial mechanical or chemical stimulation and myocardial ischaemia. The activity of 78% of spontaneously active and all quiescent neurones with left ventricular sensory fields was modified by left ventricular ischaemia. Forty-six spontaneously active neurones (85%) were polysensory with respect to mechanical and chemical stimuli. The 5 quiescent neurones responded only to chemical stimuli. Spontaneously active neurones associated with left ventricular mechanosensory endings (37 neurones) generated four different activity patterns in response to similar mechanical stimuli (high or low pressure active, high-low pressure active, high-low pressure inactive). A fifth group generated activity which was not related to chamber dynamics. Adenosine, adenosine 5'-triphosphate, substance P and bradykinin modified 72, 61, 65 and 63% of the spontaneously active neurones, respectively. Maximum local mechanical or chemical stimuli enhanced activity to similar degrees, as did ischaemia. Each ischaemia-sensitive neurone displayed unique activity patterns in response to similar mechanical or chemical stimuli. Most myocardial ischemia-sensitive dorsal root ganglion neurones associated with epicardial neurites sense mechanical and multiple chemical stimuli, a small population sensing only mechanical or chemical stimuli. Activity patterns generated by these neurones depend on their primary sensory characteristics or those of other neurones that may converge on them, as well as the type and magnitude of the stimuli that impinge upon their sensory fields, both normally and during ischaemia.

  4. Isolation of sensory neurons of Aplysia californica for patch clamp recordings of glutamatergic currents.

    PubMed

    Fieber, Lynne A; Carlson, Stephen L; Kempsell, Andrew T; Greer, Justin B; Schmale, Michael C

    2013-07-10

    The marine gastropod mollusk Aplysia californica has a venerable history as a model of nervous system function, with particular significance in studies of learning and memory. The typical preparations for such studies are ones in which the sensory and motoneurons are left intact in a minimally dissected animal, or a technically elaborate neuronal co-culture of individual sensory and motoneurons. Less common is the isolated neuronal preparation in which small clusters of nominally homogeneous neurons are dissociated into single cells in short term culture. Such isolated cells are useful for the biophysical characterization of ion currents using patch clamp techniques, and targeted modulation of these conductances. A protocol for preparing such cultures is described. The protocol takes advantage of the easily identifiable glutamatergic sensory neurons of the pleural and buccal ganglia, and describes their dissociation and minimal maintenance in culture for several days without serum.

  5. Neuronal soma-satellite glial cell interactions in sensory ganglia and the participation of purinergic receptors.

    PubMed

    Gu, Yanping; Chen, Yong; Zhang, Xiaofei; Li, Guang-Wen; Wang, Congying; Huang, Li-Yen Mae

    2010-02-01

    It has been known for some time that the somata of neurons in sensory ganglia respond to electrical or chemical stimulation and release transmitters in a Ca2+-dependent manner. The function of the somatic release has not been well delineated. A unique characteristic of the ganglia is that each neuronal soma is tightly enwrapped by satellite glial cells (SGCs). The somatic membrane of a sensory neuron rarely makes synaptic contact with another neuron. As a result, the influence of somatic release on the activity of adjacent neurons is likely to be indirect and/or slow. Recent studies of neuron-SGC interactions have demonstrated that ATP released from the somata of dorsal root ganglion neurons activates SGCs. They in turn exert complex excitatory and inhibitory modulation of neuronal activity. Thus, SGCs are actively involved in the processing of afferent information. In this review, we summarize our understanding of bidirectional communication between neuronal somata and SGCs in sensory ganglia and its possible role in afferent signaling under normal and injurious conditions. The participation of purinergic receptors is emphasized because of their dominant roles in the communication.

  6. Peripherally-Derived BDNF Promotes Regeneration of Ascending Sensory Neurons after Spinal Cord Injury

    PubMed Central

    Zhang, Feng-He; Zhong, Jin-Hua; Zhou, Xin-Fu

    2008-01-01

    Background The blood brain barrier (BBB) and truncated trkB receptor on astrocytes prevent the penetration of brain derived neurotrophic factor (BDNF) applied into the peripheral (PNS) and central nervous system (CNS) thus restrict its application in the treatment of nervous diseases. As BDNF is anterogradely transported by axons, we propose that peripherally derived and/or applied BDNF may act on the regeneration of central axons of ascending sensory neurons. Methodology/Principal Findings The present study aimed to test the hypothesis by using conditioning lesion of the sciatic nerve as a model to increase the expression of endogenous BDNF in sensory neurons and by injecting exogenous BDNF into the peripheral nerve or tissues. Here we showed that most of regenerating sensory neurons expressed BDNF and p-CREB but not p75NTR. Conditioning-lesion induced regeneration of ascending sensory neuron and the increase in the number of p-Erk positive and GAP-43 positive neurons was blocked by the injection of the BDNF antiserum in the periphery. Enhanced neurite outgrowth of dorsal root ganglia (DRG) neurons in vitro by conditioning lesion was also inhibited by the neutralization with the BDNF antiserum. The delivery of exogenous BDNF into the sciatic nerve or the footpad significantly increased the number of regenerating DRG neurons and regenerating sensory axons in the injured spinal cord. In a contusion injury model, an injection of BDNF into the footpad promoted recovery of motor functions. Conclusions/Significance Our data suggest that endogenous BDNF in DRG and spinal cord is required for the enhanced regeneration of ascending sensory neurons after conditioning lesion of sciatic nerve and peripherally applied BDNF may have therapeutic effects on the spinal cord injury. PMID:18320028

  7. Emergence of spatiotemporal invariance in large neuronal ensembles in rat barrel cortex

    PubMed Central

    Jacobs, Nathan S.; Chen-Bee, Cynthia H.; Frostig, Ron D.

    2015-01-01

    Invariant sensory coding is the robust coding of some sensory information (e.g., stimulus type) despite major changes in other sensory parameters (e.g., stimulus strength). The contribution of large populations of neurons (ensembles) to invariant sensory coding is not well understood, but could offer distinct advantages over invariance in single cell receptive fields. To test invariant sensory coding in neuronal ensembles evoked by single whisker stimulation as early as primary sensory cortex, we recorded detailed spatiotemporal movies of evoked ensemble activity through the depth of rat barrel cortex using microelectrode arrays. We found that an emergent property of whisker evoked ensemble activity, its spatiotemporal profile, was notably invariant across major changes in stimulus amplitude (up to >200-fold). Such ensemble-based invariance was found for single whisker stimulation as well as for the integrated profile of activity evoked by the more naturalistic stimulation of the entire whisker array. Further, the integrated profile of whisker array evoked ensemble activity and its invariance to stimulus amplitude shares striking similarities to “funneled” tactile perception in humans. We therefore suggest that ensemble-based invariance could provide a robust neurobiological substrate for invariant sensory coding and integration at an early stage of cortical sensory processing already in primary sensory cortex. PMID:26217194

  8. Robo2 determines subtype-specific axonal projections of trigeminal sensory neurons

    PubMed Central

    Pan, Y. Albert; Choy, Margaret; Prober, David A.; Schier, Alexander F.

    2012-01-01

    How neurons connect to form functional circuits is central to the understanding of the development and function of the nervous system. In the somatosensory system, perception of sensory stimuli to the head requires specific connections between trigeminal sensory neurons and their many target areas in the central nervous system. Different trigeminal subtypes have specialized functions and downstream circuits, but it has remained unclear how subtype-specific axonal projection patterns are formed. Using zebrafish as a model system, we followed the development of two trigeminal sensory neuron subtypes: one that expresses trpa1b, a nociceptive channel important for sensing environmental chemicals; and a distinct subtype labeled by an islet1 reporter (Isl1SS). We found that Trpa1b and Isl1SS neurons have overall similar axon trajectories but different branching morphologies and distributions of presynaptic sites. Compared with Trpa1b neurons, Isl1SS neurons display reduced branch growth and synaptogenesis at the hindbrain-spinal cord junction. The subtype-specific morphogenesis of Isl1SS neurons depends on the guidance receptor Robo2. robo2 is preferentially expressed in the Isl1SS subset and inhibits branch growth and synaptogenesis. In the absence of Robo2, Isl1SS afferents acquire many of the characteristics of Trpa1b afferents. These results reveal that subtype-specific activity of Robo2 regulates subcircuit morphogenesis in the trigeminal sensory system. PMID:22190641

  9. Acute inhalation toxicity and sensory irritation of dimethylamine. [Rats, mice

    SciTech Connect

    Steinhagen, W.H.; Swenberg, J.A.; Barrow, C.S.

    1982-06-01

    The sensory irritation potential of dimethylamine (DMA) inhalation on male Fischer-344 rats and male Swiss-Webster mice was evaluated by measuring the reflex decrease in respiratory rate. In addition, the six hour LC/sub 50/ for rats exposed to dimetylamine was established. Groups of 3 or 4 rats and mice were exposed for 10 minutes to concentrations of DMA ranging from 49 to 1576 ppm during which time the respiratory rate was monitored and recorded. Sensory irritation concentration-response curves were obtained and RD/sub 50/ values (concentration which elicits a 50% decrease in respiratory rate) were determined to be 573 and 511 ppm for rats and mice, respectively. In another set of experiments seven groups of male rats were exposed to concentrations of DMA ranging from 600 to 6119 ppm for six hours. Mortality counts were made during and for 48 hours post exposure. The six hour LC/sub 50/ was determined to be 4540 ppm. Histopathologic examination of the respiratory tract revealed concentration related changes ranging from ulceration and necrosis to rhinitis, tracheitis, and emphysema. Overall, DMA was found to be less potent as a sensory irritant than other airborne irritants.

  10. Dorsoventral organization of sensory nerves in the lumbar spine as indicated by double labeling of dorsal root ganglion neurons.

    PubMed

    Takahashi, Yuzuru; Ohtori, Seiji; Takahashi, Kazuhisa

    2010-07-01

    Referred pain due to lumbar disc disorders can be analyzed using the stereoscopic structure of the peripheral sensory nervous system. The rostrocaudal structure has been clarified. The dorsoventral structure of the lumbar spine would be useful for mapping areas of pain perception in spinal disorders. The neurotracer 1,1-dioctadecyl-3,3,3,3-tetramethylindocarbocyanine perchlorate (DiI) was applied to the lateral portion of the L5/6 intervertebral disc in rats to examine the dorsoventral organization of the sensory nervous system in the lumbar spine and related tissues. Fluorogold (FG) was applied to reference sites located at the spinous process of the L5 vertebra, the L5/6 facet joint, the psoas muscle at the L5 level, or the rectus abdominis muscle at the pubic symphysis. FG was also applied to the lateral portion of the disc (DiI application site) at L5 or at the L5 level as controls for the double labeling. Labeled neurons were counted in dorsal root ganglia (DRGs) from L1 through L4. The proportion of neurons double-labeled with DiI and FG in the total number of DiI-labeled and FG-labeled neurons was 32.9% in the control group; 0% in the spinous process, 0.6% in the facet joint, 2.3% in the psoas muscle, and 0.1% in the rectus abdominis muscle. DRG neurons with dichotomizing afferent fibers were most prevalent (2.3%) between the lateral disc and the psoas muscle at the groin; they were rare or absent between the disc and other reference sites. Dorsoventral organization of the primary sensory system in the lumbar body trunk was suggested from the proportion of DRG neurons with dichotomizing afferent fibers innervating the lumbar disc and other tissues. The present findings provide a pathomechanism of groin referred pain in lumbar disc disorders.

  11. Neuronal FLT1 receptor and its selective ligand VEGF-B protect against retrograde degeneration of sensory neurons

    PubMed Central

    Dhondt, Joke; Peeraer, Eve; Verheyen, An; Nuydens, Rony; Buysschaert, Ian; Poesen, Koen; Van Geyte, Katie; Beerens, Manu; Shibuya, Masabumi; Haigh, Jody J.; Meert, Theo; Carmeliet, Peter; Lambrechts, Diether

    2011-01-01

    Even though VEGF-B is a homologue of the potent angiogenic factor VEGF, its angiogenic activities have been controversial. Intrigued by findings that VEGF-B may also affect neuronal cells, we assessed the neuroprotective and vasculoprotective effects of VEGF-B in the skin, in which vessels and nerves are functionally intertwined. Although VEGF-B and its FLT1 receptor were prominently expressed in dorsal root ganglion (DRG) neurons innervating the hindlimb skin, they were not essential for nerve function or vascularization of the skin. However, primary DRG cultures lacking VEGF-B or FLT1 exhibited increased neuronal stress and were more susceptible to paclitaxel-induced cell death. Concomitantly, mice lacking VEGF-B or a functional FLT1 developed more retrograde degeneration of sensory neurons in a model of distal neuropathy. On the other hand, the addition of the VEGF-B isoform, VEGF-B186, to DRG cultures antagonized neuronal stress, maintained the mitochondrial membrane potential and stimulated neuronal survival. Mice overexpressing VEGF-B186 or FLT1 selectively in neurons were protected against the distal neuropathy, whereas exogenous VEGF-B186, either delivered by gene transfer or as a recombinant factor, was protective by directly affecting sensory neurons and not the surrounding vasculature. Overall, this indicates that VEGF-B, instead of acting as an angiogenic factor, exerts direct neuroprotective effects through FLT1. These findings also suggest a clinically relevant role for VEGF-B in preventing distal neuropathies.—Dhondt, J., Peeraer, E., Verheyen, A., Nuydens, R., Buysschaert, I., Poesen, K., Van Geyte, K., Beerens, M., Shibuya, M., Haigh, J. J., Meert, T., Carmeliet, P., Lambrechts, D. Neuronal FLT1 receptor and its selective ligand VEGF-B protect against retrograde degeneration of sensory neurons. PMID:21248239

  12. Network Actions of Pentobarbital in the Rat Mesopontine Tegmentum on Sensory Inflow Through the Spinothalamic Tract

    PubMed Central

    Namjoshi, Dhananjay R.; McErlane, Shelly A.; Taepavarapruk, Niwat; Soja, Peter J.

    2009-01-01

    The recent discovery of a barbiturate-sensitive “general anesthesia switch” mechanism localized in the rat brain stem mesopontine tegmental anesthesia area (MPTA) has challenged the current view of the nonspecific actions of general anesthetic agents in the CNS. In this study we provide electrophysiological evidence that the antinociception, which accompanies the behavioral state resembling general anesthesia following pentobarbital (PB) microinjections into the MPTA of awake rats, could be accompanied by the attenuation of sensory transmission through the spinothalamic tract (STT). Following bilateral microinjections of PB into the MPTA spontaneous firing rate (SFR), antidromic firing index (FI), and sciatic (Sc) as well as sural (Su) nerve-evoked responses (ER) of identified lumbar STT neurons in the isoflurane-anesthetized rat were quantified using extracellular recording techniques. Microinjections of PB into the MPTA significantly suppressed the SFR (47%), magnitudes of Sc- (26%) and Su-ER (36%), and FI (41%) of STT neurons. Microinjections of PB-free vehicle control did not alter any of the above-cited electrophysiological parameters. The results from this study suggest that antinociception, which occurs during the anesthesia-like state following PB microinjections into the MPTA, may be due, in part, to (in)direct inhibition of STT neurons via switching mechanism(s) located in the MPTA. This study provides a provenance for investigating electrophysiologically the actions on STT neurons of other current agents used clinically to maintain the state of general anesthesia. PMID:19458144

  13. Calretinin Neurons in the Rat Suprachiasmatic Nucleus.

    PubMed

    Moore, Robert Y

    2016-08-01

    The hypothalamic suprachiasmatic nucleus (SCN), a circadian pacemaker, is present in all mammalian brains. It has a complex organization of peptide-containing neurons that is similar among species, but calcium-binding proteins are expressed variably. Neurons containing calretinin have been described in the SCN in a number of species but not with association to circadian function. The objective of the present study is to characterize a calretinin neuron (CAR) group in the rat anterior hypothalamus anatomically and functionally with a detailed description of its location and a quantitative analysis of neuronal calretinin immunoreactivity at 3 times of day, 0600, 1400, and 1900 h, from animals in either light-dark or constant dark conditions. CAR neurons occupy a region in the dorsal and lateral SCN with a circadian rhythm in CAR immunoreactivity with a peak at 0600 h and a rhythm in cytoplasmic CAR distribution with a peak at 1400 h. CAR neurons should be viewed as an anatomical and functional component of the rat SCN that expands the definition from observations with cell stains. CAR neurons are likely to modulate temporal regulation of calcium in synaptic transmission.

  14. Trk receptor signaling and sensory neuron fate are perturbed in human neuropathy caused by Gars mutations.

    PubMed

    Sleigh, James N; Dawes, John M; West, Steven J; Wei, Na; Spaulding, Emily L; Gómez-Martín, Adriana; Zhang, Qian; Burgess, Robert W; Cader, M Zameel; Talbot, Kevin; Yang, Xiang-Lei; Bennett, David L; Schiavo, Giampietro

    2017-03-28

    Charcot-Marie-Tooth disease type 2D (CMT2D) is a peripheral nerve disorder caused by dominant, toxic, gain-of-function mutations in the widely expressed, housekeeping gene, GARS The mechanisms underlying selective nerve pathology in CMT2D remain unresolved, as does the cause of the mild-to-moderate sensory involvement that distinguishes CMT2D from the allelic disorder distal spinal muscular atrophy type V. To elucidate the mechanism responsible for the underlying afferent nerve pathology, we examined the sensory nervous system of CMT2D mice. We show that the equilibrium between functional subtypes of sensory neuron in dorsal root ganglia is distorted by Gars mutations, leading to sensory defects in peripheral tissues and correlating with overall disease severity. CMT2D mice display changes in sensory behavior concordant with the afferent imbalance, which is present at birth and nonprogressive, indicating that sensory neuron identity is prenatally perturbed and that a critical developmental insult is key to the afferent pathology. Through in vitro experiments, mutant, but not wild-type, GlyRS was shown to aberrantly interact with the Trk receptors and cause misactivation of Trk signaling, which is essential for sensory neuron differentiation and development. Together, this work suggests that both neurodevelopmental and neurodegenerative mechanisms contribute to CMT2D pathogenesis, and thus has profound implications for the timing of future therapeutic treatments.

  15. CGRPα-expressing sensory neurons respond to stimuli that evoke sensations of pain and itch.

    PubMed

    McCoy, Eric S; Taylor-Blake, Bonnie; Zylka, Mark J

    2012-01-01

    Calcitonin gene-related peptide (CGRPα, encoded by Calca) is a classic marker of nociceptive dorsal root ganglia (DRG) neurons. Despite years of research, it is unclear what stimuli these neurons detect in vitro or in vivo. To facilitate functional studies of these neurons, we genetically targeted an axonal tracer (farnesylated enhanced green fluorescent protein; GFP) and a LoxP-stopped cell ablation construct (human diphtheria toxin receptor; DTR) to the Calca locus. In culture, 10-50% (depending on ligand) of all CGRPα-GFP-positive (+) neurons responded to capsaicin, mustard oil, menthol, acidic pH, ATP, and pruritogens (histamine and chloroquine), suggesting a role for peptidergic neurons in detecting noxious stimuli and itch. In contrast, few (2.2±1.3%) CGRPα-GFP(+) neurons responded to the TRPM8-selective cooling agent icilin. In adult mice, CGRPα-GFP(+) cell bodies were located in the DRG, spinal cord (motor neurons and dorsal horn neurons), brain and thyroid-reproducibly marking all cell types known to express Calca. Half of all CGRPα-GFP(+) DRG neurons expressed TRPV1, ∼25% expressed neurofilament-200, <10% contained nonpeptidergic markers (IB4 and Prostatic acid phosphatase) and almost none (<1%) expressed TRPM8. CGRPα-GFP(+) neurons innervated the dorsal spinal cord and innervated cutaneous and visceral tissues. This included nerve endings in the epidermis and on guard hairs. Our study provides direct evidence that CGRPα(+) DRG neurons respond to agonists that evoke pain and itch and constitute a sensory circuit that is largely distinct from nonpeptidergic circuits and TRPM8(+)/cool temperature circuits. In future studies, it should be possible to conditionally ablate CGRPα-expressing neurons to evaluate sensory and non-sensory functions for these neurons.

  16. Behavioral aging is associated with reduced sensory neuron excitability in Aplysia californica

    PubMed Central

    Kempsell, Andrew T.; Fieber, Lynne A.

    2014-01-01

    Invertebrate models have advantages for understanding the basis of behavioral aging due to their simple nervous systems and short lifespans. The potential usefulness of Aplysia californica in aging research is apparent from its long history of neurobiological research, but it has been underexploited in this model use. Aging of simple reflexes at both single sensory neuron and neural circuit levels was studied to connect behavioral aging to neurophysiological aging. The tail withdrawal reflex (TWR), righting reflex, and biting response were measured throughout sexual maturity in 3 cohorts of hatchery-reared animals of known age. Reflex times increased and reflex amplitudes decreased significantly during aging. Aging in sensory neurons of animals with deficits in measures of the TWR and biting response resulted in significantly reduced excitability in old animals compared to their younger siblings. The threshold for firing increased while the number of action potentials in response to depolarizing current injection decreased during aging in sensory neurons, but not in tail motoneurons. Glutamate receptor-activated responses in sensory neurons also decreased with aging. In old tail motoneurons, the amplitude of evoked EPSPs following tail shock decreased, presumably due to reduced sensory neuron excitability during aging. The results were used to develop stages of aging relevant to both hatchery-reared and wild-caught Aplysia. Aplysia is a viable aging model in which the contributions of differential aging of components of neural circuits may be assessed. PMID:24847260

  17. Three-Dimensional Distribution of Sensory Stimulation-Evoked Neuronal Activity of Spinal Dorsal Horn Neurons Analyzed by In Vivo Calcium Imaging

    PubMed Central

    Taniguchi, Wataru; Uta, Daisuke; Furue, Hidemasa; Ito, Seiji

    2014-01-01

    The spinal dorsal horn comprises heterogeneous populations of interneurons and projection neurons, which form neuronal circuits crucial for processing of primary sensory information. Although electrophysiological analyses have uncovered sensory stimulation-evoked neuronal activity of various spinal dorsal horn neurons, monitoring these activities from large ensembles of neurons is needed to obtain a comprehensive view of the spinal dorsal horn circuitry. In the present study, we established in vivo calcium imaging of multiple spinal dorsal horn neurons by using a two-photon microscope and extracted three-dimensional neuronal activity maps of these neurons in response to cutaneous sensory stimulation. For calcium imaging, a fluorescence resonance energy transfer (FRET)-based calcium indicator protein, Yellow Cameleon, which is insensitive to motion artifacts of living animals was introduced into spinal dorsal horn neurons by in utero electroporation. In vivo calcium imaging following pinch, brush, and heat stimulation suggests that laminar distribution of sensory stimulation-evoked neuronal activity in the spinal dorsal horn largely corresponds to that of primary afferent inputs. In addition, cutaneous pinch stimulation elicited activities of neurons in the spinal cord at least until 2 spinal segments away from the central projection field of primary sensory neurons responsible for the stimulated skin point. These results provide a clue to understand neuronal processing of sensory information in the spinal dorsal horn. PMID:25100083

  18. Three-dimensional distribution of sensory stimulation-evoked neuronal activity of spinal dorsal horn neurons analyzed by in vivo calcium imaging.

    PubMed

    Nishida, Kazuhiko; Matsumura, Shinji; Taniguchi, Wataru; Uta, Daisuke; Furue, Hidemasa; Ito, Seiji

    2014-01-01

    The spinal dorsal horn comprises heterogeneous populations of interneurons and projection neurons, which form neuronal circuits crucial for processing of primary sensory information. Although electrophysiological analyses have uncovered sensory stimulation-evoked neuronal activity of various spinal dorsal horn neurons, monitoring these activities from large ensembles of neurons is needed to obtain a comprehensive view of the spinal dorsal horn circuitry. In the present study, we established in vivo calcium imaging of multiple spinal dorsal horn neurons by using a two-photon microscope and extracted three-dimensional neuronal activity maps of these neurons in response to cutaneous sensory stimulation. For calcium imaging, a fluorescence resonance energy transfer (FRET)-based calcium indicator protein, Yellow Cameleon, which is insensitive to motion artifacts of living animals was introduced into spinal dorsal horn neurons by in utero electroporation. In vivo calcium imaging following pinch, brush, and heat stimulation suggests that laminar distribution of sensory stimulation-evoked neuronal activity in the spinal dorsal horn largely corresponds to that of primary afferent inputs. In addition, cutaneous pinch stimulation elicited activities of neurons in the spinal cord at least until 2 spinal segments away from the central projection field of primary sensory neurons responsible for the stimulated skin point. These results provide a clue to understand neuronal processing of sensory information in the spinal dorsal horn.

  19. Changes induced by peripheral nerve injury in the morphology and nanomechanics of sensory neurons

    NASA Astrophysics Data System (ADS)

    Benzina, Ouafa; Szabo, Vivien; Lucas, Olivier; Saab, Marie-belle; Cloitre, Thierry; Scamps, Frédérique; Gergely, Csilla; Martin, Marta

    2013-06-01

    Peripheral nerve injury in vivo promotes a regenerative growth in vitro characterized by an improved neurite regrowth. Knowledge of the conditioning injury effects on both morphology and mechanical properties of live sensory neurons could be instrumental to understand the cellular and molecular mechanisms leading to this regenerative growth. In the present study, we use differential interference contrast microscopy, fluorescence microscopy and atomic force microscopy (AFM) to show that conditioned axotomy, induced by sciatic nerve injury, does not increase somatic size of sensory neurons from adult mice lumbar dorsal root ganglia but promotes the appearance of longer and larger neurites and growth cones. AFM on live neurons is also employed to investigate changes in morphology and membrane mechanical properties of somas of conditioned neurons following sciatic nerve injury. Mechanical analysis of the soma allows distinguishing neurons having a regenerative growth from control ones, although they show similar shapes and sizes.

  20. [The neuronal responses of the caudate nucleus in the cat to sensory stimulation].

    PubMed

    Rodionova, E I; Pigarev, I N

    1990-01-01

    Responses of caudate neurons to a large variety of visual and other sensory stimuli were studied in alert cats. Sharp drops in the spontaneous activity of the unknown origin and differences in the activity level were revealed in adjacent parts of the caudate nucleus. The following types of neurons were recorded: neurons responding to visual stimulation; neurons responding to somatic stimulation; neurons responding to combined visual-somatic stimulation. The best response was observed to moving visual stimuli that attracted the animal's attention, alimentary objects specifically. The caudate nucleus of each hemisphere contained representation of both contra- and ipsilateral half of the animal body. Cell responses to sensory stimuli from the caudate nucleus have been compared with those from some cortical areas.

  1. Compartmentalized cGMP Responses of Olfactory Sensory Neurons in Caenorhabditis elegans.

    PubMed

    Shidara, Hisashi; Hotta, Kohji; Oka, Kotaro

    2017-04-05

    Cyclic guanosine monophosphate (cGMP) plays a crucial role as a second messenger in the regulation of sensory signal transduction in many organisms. In AWC olfactory sensory neurons of Caenorhabditis elegans, cGMP also has essential and distinctive functions in olfactory sensation and adaptation. According to molecular genetic studies, when nematodes are exposed to odorants, a decrease in cGMP regulates cGMP-gated channels for olfactory sensation. Conversely, for olfactory adaptation, an increase in cGMP activates protein kinase G to modulate cellular physiological functions. Although these opposing cGMP responses in single neurons may occur at the same time, it is unclear how cGMP actually behaves in AWC sensory neurons. A hypothetical explanation for opposing cGMP responses is region-specific behaviors in AWC: for odor sensation, cGMP levels in cilia could decrease, whereas odor adaptation is mediated by increased cGMP levels in soma. Therefore, we visualized intracellular cGMP in AWC with a genetically encoded cGMP indicator, cGi500, and examined spatiotemporal cGMP responses in AWC neurons. The cGMP imaging showed that, after odor exposure, cGMP levels in AWC cilia decreased transiently, whereas levels in dendrites and soma gradually increased. These region-specific responses indicated that the cGMP responses in AWC neurons are explicitly compartmentalized. In addition, we performed Ca(2+) imaging to examine the relationship between cGMP and Ca(2+) These results suggested that AWC sensory neurons are in fact analogous to vertebrate photoreceptor neurons.SIGNIFICANCE STATEMENT Cyclic guanosine monophosphate (cGMP) plays crucial roles in the regulation of sensory signal transduction in many animals. In AWC olfactory sensory neurons of Caenorhabditis elegans, cGMP also has essential and distinctive functions involving olfactory sensation and adaptation. Here, we visualized intracellular cGMP in AWC neurons with a genetically encoded cGMP indicator and examined how

  2. Electrical stimulation promotes sensory neuron regeneration and growth-associated gene expression.

    PubMed

    Geremia, Nicole M; Gordon, Tessa; Brushart, Thomas M; Al-Majed, Abdulhakeem A; Verge, Valerie M K

    2007-06-01

    Brief electrical stimulation enhances the regenerative ability of axotomized motor [Nix, W.A., Hopf, H.C., 1983. Electrical stimulation of regenerating nerve and its effect on motor recovery. Brain Res. 272, 21-25; Al-Majed, A.A., Neumann, C.M., Brushart, T.M., Gordon, T., 2000. Brief electrical stimulation promotes the speed and accuracy of motor axonal regeneration. J. Neurosci. 20, 2602-2608] and sensory [Brushart, T.M., Jari, R., Verge, V., Rohde, C., Gordon, T., 2005. Electrical stimulation restores the specificity of sensory axon regeneration. Exp. Neurol. 194, 221-229] neurons. Here we examined the parameter of duration of stimulation on regenerative capacity, including the intrinsic growth programs, of sensory neurons. The effect of 20 Hz continuous electrical stimulation on the number of DRG sensory neurons that regenerate their axons was evaluated following transection and surgical repair of the femoral nerve trunk. Stimulation was applied proximal to the repair site for 1 h, 3 h, 1 day, 7 days or 14 days at the time of nerve repair. Following a 21-day regeneration period, DRG neurons that regenerated axons into the muscle and cutaneous sensory nerve branches were retrogradely identified. Stimulation of 1 h led to a significant increase in DRG neurons regenerating into cutaneous and muscle branches when compared to 0 h (sham) stimulation or longer periods of stimulation. Stimulation for 1 h also significantly increased the numbers of neurons that regenerated axons beyond the repair site 4 days after lesion and was correlated with a significant increase in expression of growth-associated protein 43 (GAP-43) mRNA in the regenerating neurons at 2 days post-repair. An additional indicator of heightened plasticity following 1 h stimulation was elevated expression of brain-derived neurotrophic factor (BDNF). The effect of brief stimulation on enhancing sensory and motoneuron regeneration holds promise for inducing improved peripheral nerve repair in the

  3. TRPA1 activation in a human sensory neuronal model: relevance to cough hypersensitivity?

    PubMed

    Clarke, Rebecca; Monaghan, Kevin; About, Imad; Griffin, Caoimhin S; Sergeant, Gerard P; El Karim, Ikhlas; McGeown, J Graham; Cosby, S Louise; Curtis, Timothy M; McGarvey, Lorcan P; Lundy, Fionnuala T

    2017-09-01

    The cough reflex becomes hyperresponsive in acute and chronic respiratory diseases, but understanding the underlying mechanism is hampered by difficulty accessing human tissue containing both nerve endings and neuronal cell bodies. We refined an adult stem cell sensory neuronal model to overcome the limited availability of human neurones and applied the model to study transient receptor potential ankyrin 1 (TRPA1) channel expression and activation.Human dental pulp stem cells (hDPSCs) were differentiated towards a neuronal phenotype, termed peripheral neuronal equivalents (PNEs). Using molecular and immunohistochemical techniques, together with Ca(2+) microfluorimetry and whole cell patch clamping, we investigated roles for nerve growth factor (NGF) and the viral mimic poly I:C in TRPA1 activation.PNEs exhibited morphological, molecular and functional characteristics of sensory neurons and expressed functional TRPA1 channels. PNE treatment with NGF for 20 min generated significantly larger inward and outward currents compared to untreated PNEs in response to the TRPA1 agonist cinnamaldehyde (p<0.05). PNE treatment with poly I:C caused similar transient heightened responses to TRPA1 activation compared to untreated cells.Using the PNE neuronal model we observed both NGF and poly I:C mediated sensory neuronal hyperresponsiveness, representing potential neuro-inflammatory mechanisms associated with heightened nociceptive responses recognised in cough hypersensitivity syndrome. Copyright ©ERS 2017.

  4. Localization of the autonomic, somatic and sensory neurons innervating the cranial tibial muscle of the pig.

    PubMed

    Botti, Maddalena; Gazza, Ferdinando; Ragionieri, Luisa; Minelli, Luisa Bo; Panu, Rino

    2011-01-01

    The location of sympathetic, somatic and sensory neurons projecting to the cranial tibial muscle of the pig hindlimb was studied with the neuronal non-transynaptic tracer Fast Blue. Additionally, the number and the size of these neurons were determinated. The Fast blue, randomly applied to the cranial tibial muscle belly of 3 pigs, labelled sympathetic neurons in the ipsilateral L5-S3 and contralateral S1 sympathetic trunk ganglia and in the prevertebral caudal mesenteric ganglia of both sides. The somatic motoneurons were identified in the ipsilateral ventral horn of the S1 segment of spinal cord, while the sensory neurons were located in the ipsilateral L7-S1 spinal ganglia. The diameter of the multipolar sympathetic neurons oscillated between 26 and 46 microm in the sympathetic trunk ganglia and between 18 and 42 microm in the caudal mesenteric ganglia. The size of the multipolar spinal motoneurons oscillated between 33 and 102 microm. The size of the pseudounipolar sensory neurons oscillated between 23 and 67 microm. In all ganglia, the labelled neurons were localized at random and did not show a somatotopic distribution. Our results document a conspicuous autonomic innervation projecting to the "classic" skeletal cranial tibial muscle. Probably this innervation is destined to the muscle vessels.

  5. Dopamine neurons code subjective sensory experience and uncertainty of perceptual decisions

    PubMed Central

    de Lafuente, Victor; Romo, Ranulfo

    2011-01-01

    Midbrain dopamine (DA) neurons respond to sensory stimuli associated with future rewards. When reward is delivered probabilistically, DA neurons reflect this uncertainty by increasing their firing rates in a period between the sensory cue and reward delivery time. Probability of reward, however, has been externally conveyed by visual cues, and it is not known whether DA neurons would signal uncertainty arising internally. Here we show that DA neurons code the uncertainty associated with a perceptual judgment about the presence or absence of a vibrotactile stimulus. We observed that uncertainty modulates the activity elicited by a go cue instructing monkey subjects to communicate their decisions. That is, the same go cue generates different DA responses depending on the uncertainty level of a judgment made a few seconds before the go instruction. Easily detected suprathreshold stimuli elicit small DA responses, indicating that future reward will not be a surprising event. In contrast, the absence of a sensory stimulus generates large DA responses associated with uncertainty: was the stimulus truly absent, or did a low-amplitude vibration go undetected? In addition, the responses of DA neurons to the stimulus itself increase with vibration amplitude, but only when monkeys correctly detect its presence. This finding suggests that DA activity is not related to actual intensity but rather to perceived intensity. Therefore, in addition to their well-known role in reward prediction, DA neurons code subjective sensory experience and uncertainty arising internally from perceptual decisions. PMID:22106310

  6. The Cancer Chemotherapeutic Paclitaxel Increases Human and Rodent Sensory Neuron Responses to TRPV1 by Activation of TLR4

    PubMed Central

    Li, Yan; Adamek, Pavel; Zhang, Haijun; Tatsui, Claudio Esteves; Rhines, Laurence D.; Mrozkova, Petra; Li, Qin; Kosturakis, Alyssa K.; Cassidy, Ryan M.; Harrison, Daniel S.; Cata, Juan P.; Sapire, Kenneth; Zhang, Hongmei; Kennamer-Chapman, Ross M.; Jawad, Abdul Basit; Ghetti, Andre; Yan, Jiusheng; Palecek, Jiri

    2015-01-01

    Peripheral neuropathy is dose limiting in paclitaxel cancer chemotherapy and can result in both acute pain during treatment and chronic persistent pain in cancer survivors. The hypothesis tested was that paclitaxel produces these adverse effects at least in part by sensitizing transient receptor potential vanilloid subtype 1 (TRPV1) through Toll-like receptor 4 (TLR4) signaling. The data show that paclitaxel-induced behavioral hypersensitivity is prevented and reversed by spinal administration of a TRPV1 antagonist. The number of TRPV1+ neurons is increased in the dorsal root ganglia (DRG) in paclitaxel-treated rats and is colocalized with TLR4 in rat and human DRG neurons. Cotreatment of rats with lipopolysaccharide from the photosynthetic bacterium Rhodobacter sphaeroides (LPS-RS), a TLR4 inhibitor, prevents the increase in numbers of TRPV1+ neurons by paclitaxel treatment. Perfusion of paclitaxel or the archetypal TLR4 agonist LPS activated both rat DRG and spinal neurons directly and produced acute sensitization of TRPV1 in both groups of cells via a TLR4-mediated mechanism. Paclitaxel and LPS sensitize TRPV1 in HEK293 cells stably expressing human TLR4 and transiently expressing human TRPV1. These physiological effects also are prevented by LPS-RS. Finally, paclitaxel activates and sensitizes TRPV1 responses directly in dissociated human DRG neurons. In summary, TLR4 was activated by paclitaxel and led to sensitization of TRPV1. This mechanism could contribute to paclitaxel-induced acute pain and chronic painful neuropathy. SIGNIFICANCE STATEMENT In this original work, it is shown for the first time that paclitaxel activates peripheral sensory and spinal neurons directly and sensitizes these cells to transient receptor potential vanilloid subtype 1 (TRPV1)-mediated capsaicin responses via Toll-like receptor 4 (TLR4) in multiple species. A direct functional interaction between TLR4 and TRPV1 is shown in rat and human dorsal root ganglion neurons, TLR4/TRPV1

  7. Neonatal sciatic nerve transection induces TUNEL labeling of neurons in the rat spinal cord and DRG.

    PubMed

    Oliveira, A L; Risling, M; Deckner, M; Lindholm, T; Langone, F; Cullheim, S

    1997-09-08

    Transection of a peripheral nerve in neonatal rats induces an extensive death of axotomized neurons. We demonstrate here that spinal motoneurons and sensory dorsal root ganglia neurons become TUNEL-labeled after sciatic nerve transection in neonatal rats, thus indicating that apoptotic mechanisms are involved in the death process. Interestingly, there is also a profound increase of TUNEL-labeled interneurons in the deep dorsal horn. This location suggests that an intact afferent input and/or contact with target cells is essential for interneuronal survival. Death of motoneurons and sensory neurons could be a result of the injury per se and/or the deprivation of neurotrophic substances, secondary to the loss of contact with target cells.

  8. Localization and properties of respiratory neurons in the rostral pons of the newborn rat.

    PubMed

    Kobayashi, S; Onimaru, H; Inoue, M; Inoue, T; Sasa, R

    2005-01-01

    The distribution and discharge pattern of respiratory neurons in the 'pneumotaxic center' of the rostral pons in the rat has remained unknown. We performed optical recordings and whole-cell patch clamp recordings to clarify respiratory neuron activity in the rostral pons of a brainstem-spinal cord preparation from a newborn rat. Inspiratory nerve activity was recorded in the 4th cervical nerve and used as a trigger signal for optical recordings. Respiratory neuron activity was detected in the limited region of the rostral-lateral pons. The main active region was presumed to be primarily the Kölliker-Fuse nucleus. The location of respiratory neurons was further confirmed by Lucifer Yellow staining after conducting whole-cell recordings. From a membrane potential analysis of the respiratory neurons in the rostral pons, the respiratory neurons were divided into four types: inspiratory neuron (71.9%), pre-inspiratory neuron (5.3%), post-inspiratory neuron (19.3%), and expiratory neuron (3.5%). A noticeable difference between pontine and medullary respiratory neurons was that post-inspiratory neurons were more frequently encountered in the pons. Application of a mu-opioid agonist, [d-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin, transformed the burst pattern of post-inspiratory neurons into that of pre-inspiratory neurons. The electrical stimulation of the sensory root of the trigeminal nerve induced three types of responses in 85% of pontine respiratory neurons: inhibitory postsynaptic potentials (42.7%), excitatory postsynaptic potentials (37.7%) and no response (15.1%). Our findings provide the first evidence in the rat for the presence of respiratory neurons in the rostral pons, with localization in the lateral region approximately overlapping with the Kölliker-Fuse nucleus.

  9. A 3’UTR Pumilio binding element directs translational activation in olfactory sensory neurons

    PubMed Central

    Kaye, Julia A.; Rose, Natalie C.; Goldsworthy, Brett; Goga, Andrei; L'Etoile, Noelle D.

    2014-01-01

    Summary Prolonged stimulation leads to specific and stable changes in an animal’s behavior. In interneurons, this plasticity requires spatial and temporal control of neuronal protein synthesis. Whether such translational control occurs in sensory neurons is not known. Adaptation of the AWC olfactory sensory neurons of C. elegans requires the cGMP-dependent protein kinase EGL-4. Here we show that the PUF FBF-1 is required in the adult AWC for adaptation and in the odor-adapted animal, increases translation from the egl-4 3’ UTR. Further, the PUF protein may localize translation near the sensory cilia and cell body. Although the RNA-binding PUF proteins have been shown to promote plasticity in development by temporally and spatially repressing translation; this work reveals that in the adult nervous system, they can work in a different way to promote experience-dependent plasticity by activating translation in response to environmental stimulation. PMID:19146813

  10. Ciliary neurotrophic factor activates NF-κB to enhance mitochondrial bioenergetics and prevent neuropathy in sensory neurons of streptozotocin-induced diabetic rodents.

    PubMed

    Saleh, Ali; Roy Chowdhury, Subir K; Smith, Darrell R; Balakrishnan, Savitha; Tessler, Lori; Martens, Corina; Morrow, Dwane; Schartner, Emily; Frizzi, Katie E; Calcutt, Nigel A; Fernyhough, Paul

    2013-02-01

    Diabetes causes mitochondrial dysfunction in sensory neurons that may contribute to peripheral neuropathy. Ciliary neurotrophic factor (CNTF) promotes sensory neuron survival and axon regeneration and prevents axonal dwindling, nerve conduction deficits and thermal hypoalgesia in diabetic rats. In this study, we tested the hypothesis that CNTF protects sensory neuron function during diabetes through normalization of impaired mitochondrial bioenergetics. In addition, we investigated whether the NF-κB signal transduction pathway was mobilized by CNTF. Neurite outgrowth of sensory neurons derived from streptozotocin (STZ)-induced diabetic rats was reduced compared to neurons from control rats and exposure to CNTF for 24 h enhanced neurite outgrowth. CNTF also activated NF-κB, as assessed by Western blotting for the NF-κB p50 subunit and reporter assays for NF-κB promoter activity. Conversely, blockade of NF-κB signaling using SN50 peptide inhibited CNTF-mediated neurite outgrowth. Studies in mice with STZ-induced diabetes demonstrated that systemic therapy with CNTF prevented functional indices of peripheral neuropathy along with deficiencies in dorsal root ganglion (DRG) NF-κB p50 expression and DNA binding activity. DRG neurons derived from STZ-diabetic mice also exhibited deficiencies in maximal oxygen consumption rate and associated spare respiratory capacity that were corrected by exposure to CNTF for 24 h in an NF-κB-dependent manner. We propose that the ability of CNTF to enhance axon regeneration and protect peripheral nerve from structural and functional indices of diabetic peripheral neuropathy is associated with targeting of mitochondrial function, in part via NF-κB activation, and improvement of cellular bioenergetics.

  11. Prostaglandin potentiates 5-HT responses in stomach and ileum innervating visceral afferent sensory neurons

    SciTech Connect

    Kim, Sojin; Jin, Zhenhua; Lee, Goeun; Park, Yong Seek; Park, Cheung-Seog; Jin, Young-Ho

    2015-01-02

    Highlights: • Prostaglandin E2 (PGE{sub 2}) effect was tested on visceral afferent neurons. • PGE{sub 2} did not evoke response but potentiated serotonin (5-HT) currents up to 167%. • PGE{sub 2}-induced potentiation was blocked by E-prostanoid type 4 receptors antagonist. • PGE{sub 2} effect on 5-HT response was also blocked by protein kinase A inhibitor KT5720. • Thus, PGE{sub 2} modulate visceral afferent neurons via synergistic signaling with 5-HT. - Abstract: Gastrointestinal disorder is a common symptom induced by diverse pathophysiological conditions that include food tolerance, chemotherapy, and irradiation for therapy. Prostaglandin E{sub 2} (PGE{sub 2}) level increase was often reported during gastrointestinal disorder and prostaglandin synthetase inhibitors has been used for ameliorate the symptoms. Exogenous administration of PGE{sub 2} induces gastrointestinal disorder, however, the mechanism of action is not known. Therefore, we tested PGE{sub 2} effect on visceral afferent sensory neurons of the rat. Interestingly, PGE{sub 2} itself did not evoked any response but enhanced serotonin (5-HT)-evoked currents up to 167% of the control level. The augmented 5-HT responses were completely inhibited by a 5-HT type 3 receptor antagonist, ondansetron. The PGE{sub 2}-induced potentiation were blocked by a selective E-prostanoid type4 (EP{sub 4}) receptors antagonist, L-161,982, but type1 and 2 receptor antagonist AH6809 has no effect. A membrane permeable protein kinase A (PKA) inhibitor, KT5720 also inhibited PGE{sub 2} effects. PGE{sub 2} induced 5-HT current augmentation was observed on 15% and 21% of the stomach and ileum projecting neurons, respectively. Current results suggest a synergistic signaling in visceral afferent neurons underlying gastrointestinal disorder involving PGE{sub 2} potentiation of 5-HT currents. Our findings may open a possibility for screen a new type drugs with lower side effects than currently using steroidal prostaglandin

  12. Mathematical Relationships between Neuron Morphology and Neurite Growth Dynamics in Drosophila melanogaster Larva Class IV Sensory Neurons

    NASA Astrophysics Data System (ADS)

    Ganguly, Sujoy; Liang, Xin; Grace, Michael; Lee, Daniel; Howard, Jonathon

    The morphology of neurons is diverse and reflects the diversity of neuronal functions, yet the principles that govern neuronal morphogenesis are unclear. In an effort to better understand neuronal morphogenesis we will be focusing on the development of the dendrites of class IV sensory neuron in Drosophila melanogaster. In particular we attempt to determine how the the total length, and the number of branches of dendrites are mathematically related to the dynamics of neurite growth and branching. By imaging class IV neurons during early embryogenesis we are able to measure the change in neurite length l (t) as a function of time v (t) = dl / dt . We found that the distribution of v (t) is well characterized by a hyperbolic secant distribution, and that the addition of new branches per unit time is well described by a Poisson process. Combining these measurements with the assumption that branching occurs with equal probability anywhere along the dendrite we were able to construct a mathematical model that provides reasonable agreement with the observed number of branches, and total length of the dendrites of the class IV sensory neuron.

  13. Fibroblast-like synovial cells from normal and inflamed knee joints differently affect the expression of pain-related receptors in sensory neurones: a co-culture study.

    PubMed

    von Banchet, Gisela Segond; Richter, Jonny; Hückel, Marion; Rose, Christina; Bräuer, Rolf; Schaible, Hans-Georg

    2007-01-01

    Innervation of the joint with thinly myelinated and unmyelinated sensory nerve fibres is crucial for the occurrence of joint pain. During inflammation in the joint, sensory fibres show changes in the expression of receptors that are important for the activation and sensitization of the neurones and the generation of joint pain. We recently reported that both neurokinin 1 receptors and bradykinin 2 receptors are upregulated in dorsal root ganglion (DRG) neurones (the cell bodies of sensory fibres) in the course of acute and chronic antigen-induced arthritis in the rat. In this study, we begin to address mechanisms of the interaction between fibroblast-like synovial (FLS) cells and sensory neurones by establishing a co-culture system of FLS cells and DRG neurones. The proportion of DRG neurones expressing neurokinin 1 receptor-like immunoreactivity was not altered in the co-culture with FLS cells from normal joints but was significantly upregulated using FLS cells from knee joints of rats with antigen-induced arthritis. The proportion of DRG neurones expressing bradykinin 2 receptors was slightly upregulated in the presence of FLS cells from normal joints but upregulation was more pronounced in DRG neurones co-cultured with FLS cells from acutely inflamed joints. In addition, the expression of the transient receptor potential V1 (TRPV1) receptor, which is involved in inflammation-evoked thermal hyperalgesia, was mainly upregulated by co-culturing DRG neurones with FLS cells from chronically inflamed joints. Upregulation of neurokinin 1 receptors but not of bradykinin 2 and TRPV1 receptors was also observed when only the supernatant of FLS cells from acutely inflamed joint was added to DRG neurones. Addition of indomethacin to co-cultures inhibited the effect of FLS cells from acutely inflamed joints on neurokinin 1 receptor expression, suggesting an important role for prostaglandins. Collectively, these data show that FLS cells are able to induce an upregulation of

  14. Distribution of binding sites for the plant lectin Ulex europaeus agglutinin I on primary sensory neurones in seven different mammalian species.

    PubMed

    Gerke, Michelle B; Plenderleith, Mark B

    2002-01-01

    There is an increasing body of evidence to suggest that different functional classes of neurones express characteristic cell-surface carbohydrates. Previous studies have shown that the plant lectin Ulex europaeus agglutinin-I (UEA) binds to a population of small to medium diameter primary sensory neurones in rabbits and humans. This suggests that a fucose-containing glycoconjugate may be expressed by nociceptive primary sensory neurones. In order to determine the extent to which this glycoconjugate is expressed by other species, in the current study, we have examined the distribution of UEA-binding sites on primary sensory neurones in seven different mammals. Binding sites for UEA were associated with the plasma membrane and cytoplasmic granules of small to medium dorsal root ganglion cells and their axon terminals in laminae I-III of the grey matter of the spinal cord, in the rabbit, cat and marmoset monkey. However, no binding was observed in either the dorsal root ganglia or spinal cord in the mouse, rat, guinea pig or flying fox. These results indicate an inter-species variation in the expression of cell-surface glycoconjugates on mammalian primary sensory neurones.

  15. Correlations between the activity of sensory neurons and behavior: how much do they tell us about a neuron's causality?

    PubMed

    Nienborg, Hendrikje; Cumming, Bruce

    2010-06-01

    How the activity of sensory neurons elicits perceptions and guides behavior is central to our understanding of the brain and is a subject of intense investigation in neuroscience. Correlations between the activity of sensory neurons and behavior have been widely observed and are sometimes used to infer how neurons are used to guide a certain behavior. This view is challenged firstly by theoretical considerations that these correlations rely on the existence of correlated noise and its structure, and secondly by recent empirical observations suggesting that such correlated noise is not a fixed network property but that it depends on various sources, and varies with a subject's mental state. 2010 Elsevier Ltd. All rights reserved.

  16. TRPM8 function and expression in vagal sensory neurons and afferent nerves innervating guinea pig esophagus.

    PubMed

    Yu, Xiaoyun; Hu, Youtian; Ru, Fei; Kollarik, Marian; Undem, Bradley J; Yu, Shaoyong

    2015-03-15

    Sensory transduction in esophageal afferents requires specific ion channels and receptors. TRPM8 is a new member of the transient receptor potential (TRP) channel family and participates in cold- and menthol-induced sensory transduction, but its role in visceral sensory transduction is still less clear. This study aims to determine TRPM8 function and expression in esophageal vagal afferent subtypes. TRPM8 agonist WS-12-induced responses were first determined in nodose and jugular neurons by calcium imaging and then investigated by whole cell patch-clamp recordings in Dil-labeled esophageal nodose and jugular neurons. Extracellular single-unit recordings were performed in nodose and jugular C fiber neurons using ex vivo esophageal-vagal preparations with intact nerve endings in the esophagus. TRPM8 mRNA expression was determined by single neuron RT-PCR in Dil-labeled esophageal nodose and jugular neurons. The TRPM8 agonist WS-12 elicited calcium influx in a subpopulation of jugular but not nodose neurons. WS-12 activated outwardly rectifying currents in esophageal Dil-labeled jugular but not nodose neurons in a dose-dependent manner, which could be inhibited by the TRPM8 inhibitor AMTB. WS-12 selectively evoked action potential discharges in esophageal jugular but not nodose C fibers. Consistently, TRPM8 transcripts were highly expressed in esophageal Dil-labeled TRPV1-positive jugular neurons. In summary, the present study demonstrated a preferential expression and function of TRPM8 in esophageal vagal jugular but not nodose neurons and C fiber subtypes. This provides a distinctive role of TRPM8 in esophageal sensory transduction and may lead to a better understanding of the mechanisms of esophageal sensation and nociception. Copyright © 2015 the American Physiological Society.

  17. TRPM8 function and expression in vagal sensory neurons and afferent nerves innervating guinea pig esophagus

    PubMed Central

    Yu, Xiaoyun; Hu, Youtian; Ru, Fei; Kollarik, Marian; Undem, Bradley J.

    2015-01-01

    Sensory transduction in esophageal afferents requires specific ion channels and receptors. TRPM8 is a new member of the transient receptor potential (TRP) channel family and participates in cold- and menthol-induced sensory transduction, but its role in visceral sensory transduction is still less clear. This study aims to determine TRPM8 function and expression in esophageal vagal afferent subtypes. TRPM8 agonist WS-12-induced responses were first determined in nodose and jugular neurons by calcium imaging and then investigated by whole cell patch-clamp recordings in Dil-labeled esophageal nodose and jugular neurons. Extracellular single-unit recordings were performed in nodose and jugular C fiber neurons using ex vivo esophageal-vagal preparations with intact nerve endings in the esophagus. TRPM8 mRNA expression was determined by single neuron RT-PCR in Dil-labeled esophageal nodose and jugular neurons. The TRPM8 agonist WS-12 elicited calcium influx in a subpopulation of jugular but not nodose neurons. WS-12 activated outwardly rectifying currents in esophageal Dil-labeled jugular but not nodose neurons in a dose-dependent manner, which could be inhibited by the TRPM8 inhibitor AMTB. WS-12 selectively evoked action potential discharges in esophageal jugular but not nodose C fibers. Consistently, TRPM8 transcripts were highly expressed in esophageal Dil-labeled TRPV1-positive jugular neurons. In summary, the present study demonstrated a preferential expression and function of TRPM8 in esophageal vagal jugular but not nodose neurons and C fiber subtypes. This provides a distinctive role of TRPM8 in esophageal sensory transduction and may lead to a better understanding of the mechanisms of esophageal sensation and nociception. PMID:25591866

  18. TRPA1 is a major oxidant sensor in murine airway sensory neurons

    PubMed Central

    Bessac, Bret F.; Sivula, Michael; von Hehn, Christian A.; Escalera, Jasmine; Cohn, Lauren; Jordt, Sven-Eric

    2008-01-01

    Sensory neurons in the airways are finely tuned to respond to reactive chemicals threatening airway function and integrity. Nasal trigeminal nerve endings are particularly sensitive to oxidants formed in polluted air and during oxidative stress as well as to chlorine, which is frequently released in industrial and domestic accidents. Oxidant activation of airway neurons induces respiratory depression, nasal obstruction, sneezing, cough, and pain. While normally protective, chemosensory airway reflexes can provoke severe complications in patients affected by inflammatory airway conditions like rhinitis and asthma. Here, we showed that both hypochlorite, the oxidizing mediator of chlorine, and hydrogen peroxide, a reactive oxygen species, activated Ca2+ influx and membrane currents in an oxidant-sensitive subpopulation of chemosensory neurons. These responses were absent in neurons from mice lacking TRPA1, an ion channel of the transient receptor potential (TRP) gene family. TRPA1 channels were strongly activated by hypochlorite and hydrogen peroxide in primary sensory neurons and heterologous cells. In tests of respiratory function, Trpa1–/– mice displayed profound deficiencies in hypochlorite- and hydrogen peroxide–induced respiratory depression as well as decreased oxidant-induced pain behavior. Our results indicate that TRPA1 is an oxidant sensor in sensory neurons, initiating neuronal excitation and subsequent physiological responses in vitro and in vivo. PMID:18398506

  19. TRPA1 is a major oxidant sensor in murine airway sensory neurons.

    PubMed

    Bessac, Bret F; Sivula, Michael; von Hehn, Christian A; Escalera, Jasmine; Cohn, Lauren; Jordt, Sven-Eric

    2008-05-01

    Sensory neurons in the airways are finely tuned to respond to reactive chemicals threatening airway function and integrity. Nasal trigeminal nerve endings are particularly sensitive to oxidants formed in polluted air and during oxidative stress as well as to chlorine, which is frequently released in industrial and domestic accidents. Oxidant activation of airway neurons induces respiratory depression, nasal obstruction, sneezing, cough, and pain. While normally protective, chemosensory airway reflexes can provoke severe complications in patients affected by inflammatory airway conditions like rhinitis and asthma. Here, we showed that both hypochlorite, the oxidizing mediator of chlorine, and hydrogen peroxide, a reactive oxygen species, activated Ca(2+) influx and membrane currents in an oxidant-sensitive subpopulation of chemosensory neurons. These responses were absent in neurons from mice lacking TRPA1, an ion channel of the transient receptor potential (TRP) gene family. TRPA1 channels were strongly activated by hypochlorite and hydrogen peroxide in primary sensory neurons and heterologous cells. In tests of respiratory function, Trpa1(-/-) mice displayed profound deficiencies in hypochlorite- and hydrogen peroxide-induced respiratory depression as well as decreased oxidant-induced pain behavior. Our results indicate that TRPA1 is an oxidant sensor in sensory neurons, initiating neuronal excitation and subsequent physiological responses in vitro and in vivo.

  20. Response properties of temporomandibular joint mechanosensitive neurons in the trigeminal sensory complex of the rabbit.

    PubMed

    Suzuki, Osuke; Tsuboi, Akito; Tabata, Takayoshi; Takafuji, Yasuo; Sakurai, Takeshi; Watanabe, Makoto

    2012-10-01

    The neurophysiological properties of neurons sensitive to TMJ movement (TMJ neurons) in the trigeminal sensory complex (Vcomp) during passive movement of the isolated condyle were examined in 46 rabbits. Discharges of TMJ neurons from the rostral part of the Vcomp were recorded with a microelectrode when the isolated condyle was moved manually and with a computer-regulated mechanostimulator. A total of 443 neurons responding to mechanical stimulation of the face and oral cavity were recorded from the brainstem. Twenty-one TMJ neurons were detected rostrocaudally from the dorsal part of the trigeminal principal sensory nucleus (NVsnpr), subnucleus oralis of the trigeminal spinal nucleus, and reticular formation surrounding the trigeminal motor nucleus. Most of the TMJ neurons were located in the dorso-rostral part of the NVsnpr. Of the TMJ units recorded, 90 % were slowly adapting and 26 % had an accompanying resting discharge. The majority (86 %) of the TMJ units responded to the movement of the isolated condyle in the anterior and/or ventral directions, and half were sensitive to the condyle movement in a single direction. The discharge frequencies of TMJ units increased as the condyle displacement and constant velocity (5 mm/s) increased within a 5-mm anterior displacement of the isolated condyle. Based on these results, we conclude that sensory information is processed by TMJ neurons encoding at least joint position and displacement in the physiological range of mandibular displacement.

  1. Increased susceptibility of gastric mucosa to ulcerogenic stimulation in diabetic rats–role of capsaicin-sensitive sensory neurons

    PubMed Central

    Tashima, Kimihito; Korolkiewicz, Roman; Kubomi, Masafumi; Takeuchi, Koji

    1998-01-01

    We examined the gastric mucosal blood flow (GMBF) and ulcerogenic responses following barrier disruption induced by sodium taurocholate (TC) in diabetic rats and investigated the role of capsaicin-sensitive sensory neurons in these responses.Animals were injected streptozotocin (STZ: 70 mg kg−1, i.p.) and used after 5, 10 and 15 weeks of diabetes with blood glucose levels of >350 mg dl−1. The stomach was mounted on an ex-vivo chamber under urethane anaesthesia and exposed to 20 mM TC plus 50 mM HCl for 30 min in the presence of omeprazole. Gastric transmucosal potential difference (PD), GMBF, and luminal acid loss (H+ back-diffusion) were measured before and after exposure to 20 mM TC, and the mucosa was examined for lesions 90 min after TC treatment.Mucosal application of TC caused PD reduction in all groups; the degree of PD reduction was similar between normal and diabetic rats, although basal PD values were lower in diabetic rats. In normal rats, TC treatment caused luminal acid loss, followed by an increase of GMBF, resulting in minimal damage in the mucosa.The increased GMBF responses associated with H+ back-diffusion were mitigated in STZ-treated rats, depending on the duration of diabetes, and severe haemorrhagic lesions occurred in the stomach after 10 weeks of diabetes.Intragastric application of capsaicin increased GMBF in normal rats, but such responses were mitigated in STZ diabetic rats. The amount of CGRP released in the isolated stomach in response to capsaicin was significantly lower in diabetic rats when compared to controls.The deleterious influences on GMBF and mucosal ulcerogenic responses in STZ-diabetic rats were partially but significantly antagonized by daily insulin (4 units rat−1) treatment.These results suggest that the gastric mucosa of diabetic rats is more vulnerable to acid injury following barrier disruption, and this change is insulin-sensitive and may be partly accounted for by the impairment of GMBF

  2. Compound action potential of sensory tail nerves in the rat.

    PubMed

    Leandri, Massimo; Saturno, Moreno; Cilli, Michele; Bisaglia, Michela; Lunardi, Gianluigi

    2007-01-01

    Assessment of the conduction velocity of motor fibers of the rat tail nerves has been used by some authors in the past, but very little is known about the sensory fibers. In 10 adult rats, weighing between 320 and 380 g, responses from the nerves and muscles of the tail have been recorded after stimulation at its root and tip. It was found that stimulation of the tip involved mainly sensory fibers, of which two main groups could be identified. One faster group, conducting within the range of 38-27 m/s, and one slower group with range 14-7 m/s. The bipolar recording configuration was found to be optimal for sensory recording. Stimulation of the tail root evoked a motor response, which was preceded by a very small neurographic activity, due to the fastest sensory fibers conducting antidromically. The conduction velocity of motor fibers was calculated to be approximately 19 m/s. Distance traveled by the volley can be assessed with excellent precision on the tail nerves; hence the calculated conduction velocities are highly reliable and reproducible. We propose that the tail nerves may be a useful tool for evaluation of conduction velocity of Abeta and Adelta afferents. As the technique is just minimally invasive, the test can be repeated a number of times in animals under chronic experimental conditions.

  3. Atypical expression of Drosophila gustatory receptor genes in sensory and central neurons.

    PubMed

    Thorne, Natasha; Amrein, Hubert

    2008-02-01

    Members of the Drosophila gustatory receptor (Gr) gene family are generally expressed in chemosensory neurons and are known to mediate the perception of sugars, bitter substrates, CO(2), and pheromones. The Gr gene family consists of 68 members, many of which are organized in gene clusters of up to six genes, yet only expression of about 15 Gr genes has been characterized in detail prior to this study. Here we describe the first comprehensive expression analysis of six highly conserved Gr genes, Gr28a and Gr28b.a to Gr28b.e. Four of these Gr genes are not only expressed in the characteristic pattern associated with previously analyzed Gr genes-chemosensory neurons of the gustatory and olfactory system-but several other types of sensory neurons and neurons in the brain. Specifically, we show that several of the Gr28 genes are expressed in abdominal multidendritic neurons, putative hygroreceptive neurons of the arista, neurons associated with the Johnston's organ, peripheral proprioceptive neurons in the legs, neurons in the larval and adult brain, and oenocytes. Thus, our findings suggest that some Gr genes are utilized in nongustatory roles in the nervous system and tissues involved in proprioception, hygroreception, and other sensory modalities. It is also possible that the Gr28 genes have chemosensory roles in the detection of internal ligands. (c) 2007 Wiley-Liss, Inc.

  4. Endogenous angiotensinergic system in neurons of rat and human trigeminal ganglia

    PubMed Central

    Imboden, Hans; Patil, Jaspal; Nussberger, Juerg; Nicoud, Françoise; Hess, Benno; Ahmed, Nermin; Schaffner, Thomas; Wellner, Maren; Müller, Dominik; Inagami, Tadashi; Senbonmatsu, Takaaki; Pavel, Jaroslav; Saavedra, Juan M.

    2009-01-01

    To clarify the role of Angiotensin II (Ang II) in the sensory system and especially in the trigeminal ganglia, we studied the expression of angiotensinogen (Ang-N)-, renin-, angiotensin converting enzyme (ACE)- and cathepsin D-mRNA, and the presence of Ang II and substance P in the rat and human trigeminal ganglia. The rat trigeminal ganglia expressed substantial amounts of Ang-N- and ACE mRNA as determined by quantitative real time PCR. Renin mRNA was untraceable in rat samples. Cathepsin D was detected in the rat trigeminal ganglia indicating the possibility of existence of pathways alternative to renin for Ang I formation. In situ hybridization in rat trigeminal ganglia revealed expression of Ang-N mRNA in the cytoplasm of numerous neurons. By using immunocytochemistry, a number of neurons and their processes in both the rat and human trigeminal ganglia were stained for Ang II. Post in situ hybridization immunocytochemistry reveals that in the rat trigeminal ganglia some, but not all Ang-N mRNA-positive neurons marked for Ang II. In some neurons Substance P was found colocalized with Ang II. Angiotensins from rat trigeminal ganglia were quantitated by radioimmunoassay with and without prior separation by high performance liquid chromatography. Immunoreactive angiotensin II (ir-Ang II) was consistently present and the sum of true Ang II (1-8) octapeptide and its specifically measured metabolites were found to account for it. Radioimmunological and immunocytochemical evidence of ir-Ang II in neuronal tissue is compatible with Ang II as a neurotransmitter. In conclusion, these results suggest that Ang II could be produced locally in the neurons of rat trigeminal ganglia. The localization and colocalization of neuronal Ang II with Substance P in the trigeminal ganglia neurons may be the basis for a participation and function of Ang II in the regulation of nociception and migraine pathology. PMID:19323983

  5. Development of sensory motor reflexes in 2 G exposed rats.

    PubMed

    Wubbels, Réne; Bouët, Valentine; de Jong, Herman; Gramsbergen, Albert

    2004-07-01

    During gestation and early postnatal development, the animal's size and weight rapidly increase. Within that period, gravity affects sensory and motor development. We studied age-dependent modifications of several types of motor reflexes in 5 groups of rats conceived, born and reared in hypergravity (HG; 2 g). These rats were transferred to normal gravity (NG; 1 g) at various postnatal days, and their behavioral reflexes were compared with a control group which was constantly kept under NG. HG induced a retarded development of vestibular dependent reflexes. Other types of motor behavior were not delayed.

  6. Distinct Nav1.7-dependent pain sensations require different sets of sensory and sympathetic neurons.

    PubMed

    Minett, Michael S; Nassar, Mohammed A; Clark, Anna K; Passmore, Gayle; Dickenson, Anthony H; Wang, Fan; Malcangio, Marzia; Wood, John N

    2012-04-24

    Human acute and inflammatory pain requires the expression of voltage-gated sodium channel Nav1.7 but its significance for neuropathic pain is unknown. Here we show that Nav1.7 expression in different sets of mouse sensory and sympathetic neurons underlies distinct types of pain sensation. Ablating Nav1.7 gene (SCN9A) expression in all sensory neurons using Advillin-Cre abolishes mechanical pain, inflammatory pain and reflex withdrawal responses to heat. In contrast, heat-evoked pain is retained when SCN9A is deleted only in Nav1.8-positive nociceptors. Surprisingly, responses to the hotplate test, as well as neuropathic pain, are unaffected when SCN9A is deleted in all sensory neurons. However, deleting SCN9A in both sensory and sympathetic neurons abolishes these pain sensations and recapitulates the pain-free phenotype seen in humans with SCN9A loss-of-function mutations. These observations demonstrate an important role for Nav1.7 in sympathetic neurons in neuropathic pain, and provide possible insights into the mechanisms that underlie gain-of-function Nav1.7-dependent pain conditions.

  7. Calcium-activated chloride current expression in axotomized sensory neurons: what for?

    PubMed Central

    Boudes, Mathieu; Scamps, Frédérique

    2012-01-01

    Calcium-activated chloride currents (CaCCs) are activated by an increase in intracellular calcium concentration. Peripheral nerve injury induces the expression of CaCCs in a subset of adult sensory neurons in primary culture including mechano- and proprioceptors, though not nociceptors. Functional screenings of potential candidate genes established that Best1 is a molecular determinant for CaCC expression among axotomized sensory neurons, while Tmem16a is acutely activated by inflammatory mediators in nociceptors. In nociceptors, such CaCCs are preferentially activated under receptor-induced calcium mobilization contributing to cell excitability and pain. In axotomized mechano- and proprioceptors, CaCC activation does not promote electrical activity and prevents firing, a finding consistent with electrical silencing for growth competence of adult sensory neurons. In favor of a role in the process of neurite growth, CaCC expression is temporally correlated to neurons displaying a regenerative mode of growth. This perspective focuses on the molecular identity and role of CaCC in axotomized sensory neurons and the future directions to decipher the cellular mechanisms regulating CaCC during neurite (re)growth. PMID:22461766

  8. The sensory neurone membrane protein SNMP1 contributes to the sensitivity of a pheromone detection system.

    PubMed

    Pregitzer, P; Greschista, M; Breer, H; Krieger, J

    2014-12-01

    Male moths detect female-released sex pheromones with extraordinary sensitivity. The remarkable sensory ability is based on a cooperative interplay of pheromone binding proteins in the lymph of hair-like sensilla trichodea and pheromone receptors in the dendrites of sensory neurones. Here we examined whether in Heliothis virescens the so-called 'sensory neurone membrane protein 1' (SNMP1) may contribute to responsiveness to the pheromone component, (Z)-11-hexadecenal (Z11-16:Ald). By means of immunohistochemistry and in situ hybridization we demonstrated that SNMP1 is in fact present in cells expressing the Z11-16:Ald receptor HR13 and the dendrites of sensory neurones. To assess a possible function of SNMP1 we monitored the responsiveness of cell lines that expressed HR13 alone or the combination SNMP1/HR13 to stimulation with Z11-16:Ald by calcium imaging. It was found that SNMP1/HR13 cells were 1000-fold more sensitive to pheromone stimulation compared with HR13 cells. In contrast, cells that expressed HR13 and the non-neuronal SNMP2-type showed no change in pheromone sensitivity. Overall, our reconstitution experiments demonstrate that the presence of SNMP1 significantly increases the HR13-based responsiveness of cells to Z11-16:Ald, suggesting that SNMP1 also contributes to the response of the antennal neurones and thus to the remarkable sensitivity of the pheromone detection system.

  9. The Upregulation of α2δ-1 Subunit Modulates Activity-Dependent Ca2+ Signals in Sensory Neurons

    PubMed Central

    Margas, Wojciech; Cassidy, John S.

    2015-01-01

    As auxiliary subunits of voltage-gated Ca2+ channels, the α2δ proteins modulate membrane trafficking of the channels and their localization to specific presynaptic sites. Following nerve injury, upregulation of the α2δ-1 subunit in sensory dorsal root ganglion neurons contributes to the generation of chronic pain states; however, very little is known about the underlying molecular mechanisms. Here we show that the increased expression of α2δ-1 in rat sensory neurons leads to prolonged Ca2+ responses evoked by membrane depolarization. This mechanism is coupled to CaV2.2 channel-mediated responses, as it is blocked by a ω-conotoxin GVIA application. Once initiated, the prolonged Ca2+ transients are not dependent on extracellular Ca2+ and do not require Ca2+ release from the endoplasmic reticulum. The selective inhibition of mitochondrial Ca2+ uptake demonstrates that α2δ-1-mediated prolonged Ca2+ signals are buffered by mitochondria, preferentially activated by Ca2+ influx through CaV2.2 channels. Thus, by controlling channel abundance at the plasma membrane, the α2δ-1 subunit has a major impact on the organization of depolarization-induced intracellular Ca2+ signaling in dorsal root ganglion neurons. PMID:25878262

  10. Electrophysiological property and chemical sensitivity of primary afferent neurons that innervate rat whisker hair follicles

    PubMed Central

    Ikeda, Ryo

    2016-01-01

    Whisker hair follicles are sensory organs that sense touch and perform tactile discrimination in animals, and they are sites where sensory impulses are initiated when whisker hairs touch an object. The sensory signals are then conveyed by whisker afferent fibers to the brain for sensory perception. Electrophysiological property and chemical sensitivity of whisker afferent fibers, important factors affecting whisker sensory processing, are largely not known. In the present study, we performed patch-clamp recordings from pre-identified whisker afferent neurons in whole-mount trigeminal ganglion preparations and characterized their electrophysiological property and sensitivity to ATP, serotonin and glutamate. Of 97 whisker afferent neurons examined, 67% of them are found to be large-sized (diameter ≥45 µm) cells and 33% of them are medium- to small-sized (diameter <45 µm) cells. Almost every large-sized whisker afferent neuron fires a single action potential but many (40%) small/medium-sized whisker afferent neurons fire multiple action potentials in response to prolonged stepwise depolarization. Other electrophysiological properties including resting membrane potential, action potential threshold, and membrane input resistance are also significantly different between large-sized and small/medium-sized whisker afferent neurons. Most large-sized and many small/medium-sized whisker afferent neurons are sensitive to ATP and/or serotonin, and ATP and/or serotonin could evoke strong inward currents in these cells. In contrast, few whisker afferent neurons are sensitive to glutamate. Our results raise a possibility that ATP and/or serotonin may be chemical messengers involving sensory signaling for different types of rat whisker afferent fibers. PMID:27927797

  11. The Drosophila female aphrodisiac pheromone activates ppk23(+) sensory neurons to elicit male courtship behavior.

    PubMed

    Toda, Hirofumi; Zhao, Xiaoliang; Dickson, Barry J

    2012-06-28

    Females of many animal species emit chemical signals that attract and arouse males for mating. For example, the major aphrodisiac pheromone of Drosophila melanogaster females, 7,11-heptacosadiene (7,11-HD), is a potent inducer of male-specific courtship and copulatory behaviors. Here, we demonstrate that a set of gustatory sensory neurons on the male foreleg, defined by expression of the ppk23 marker, respond to 7,11-HD. Activity of these neurons is required for males to robustly court females or to court males perfumed with 7,11-HD. Artificial activation of these ppk23(+) neurons stimulates male-male courtship even without 7,11-HD perfuming. These data identify the ppk23(+) sensory neurons as the primary targets for female sex pheromones in Drosophila.

  12. Calcium signalling in sensory neurones and peripheral glia in the context of diabetic neuropathies.

    PubMed

    Verkhratsky, Alexei; Fernyhough, Paul

    2014-11-01

    Peripheral sensory nervous system is comprised of neurones with their axons and neuroglia that includes satellite glial cells in sensory ganglia, myelinating, non-myelinating and perisynaptic Schwann cells. Pathogenesis of peripheral diabetic polyneuropathies is associated with aberrant function of both neurones and glia. Deregulated Ca(2+) homoeostasis and aberrant Ca(2+) signalling in neuronal and glial elements contributes to many forms of neuropathology and is fundamental to neurodegenerative diseases. In diabetes both neurones and glia experience metabolic stress and mitochondrial dysfunction which lead to deregulation of Ca(2+) homeostasis and Ca(2+) signalling, which in their turn lead to pathological cellular reactions contributing to development of diabetic neuropathies. Molecular cascades responsible for Ca(2+) homeostasis and signalling, therefore, can be regarded as potential therapeutic targets. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Reduction in Voltage-Gated K+ Channel Activity in Primary Sensory Neurons in Painful Diabetic Neuropathy: Role of Brain-Derived Neurotrophic Factor

    PubMed Central

    Cao, Xue-Hong; Byun, Hee-Sun; Chen, Shao-Rui; Cai, You-Qing; Pan, Hui-Lin

    2010-01-01

    Abnormal hyperexcitability of primary sensory neurons plays an important role in neuropathic pain. Voltage-gated potassium (Kv) channels regulate neuronal excitability by affecting the resting membrane potential and influencing the repolarization and frequency of the action potential. Here we determined changes in Kv channels in dorsal root ganglion (DRG) neurons in a rat model of diabetic neuropathic pain. The densities of total Kv, A-type (IA), and sustained delayed (IK) currents were markedly reduced in medium- and large-, but not in small-, diameter DRG neurons in diabetic rats. Quantitative RT-PCR analysis revealed that the mRNA levels of IA subunits, including Kv1.4, Kv3.4, Kv4.2, and Kv4.3, in the DRG were reduced ~50% in diabetic rats compared with those in control rats. However, there were no significant differences in the mRNA levels of IK subunits (Kv1.1, Kv1.2, Kv2.1, and Kv2.2) in the DRG between the two groups. Incubation with brain-derived neurotrophic factor (BDNF) caused a large reduction in Kv currents, especially IA currents, in medium and large DRG neurons from control rats. Furthermore, the reductions in Kv currents and mRNA levels of IA subunits in diabetic rats were normalized by pretreatment with anti-BDNF antibody or K252a, a TrkB tyrosine kinase inhibitor. In addition, the number of medium and large DRG neurons with BDNF immunoreactivity was greater in diabetic than control rats. Collectively, our findings suggest that diabetes primarily reduces Kv channel activity in medium and large DRG neurons. Increased BDNF activity in these neurons likely contributes to the reduction in Kv channel function through TrkB receptor stimulation in painful diabetic neuropathy. PMID:20557422

  14. Inhibition of the plasma membrane Ca2+ pump by CD44 receptor activation of tyrosine kinases increases the action potential afterhyperpolarization in sensory neurons.

    PubMed

    Ghosh, Biswarup; Li, Yan; Thayer, Stanley A

    2011-02-16

    The cytoplasmic Ca(2+) clearance rate affects neuronal excitability, plasticity, and synaptic transmission. Here, we examined the modulation of the plasma membrane Ca(2+) ATPase (PMCA) by tyrosine kinases. In rat sensory neurons grown in culture, the PMCA was under tonic inhibition by a member of the Src family of tyrosine kinases (SFKs). Ca(2+) clearance accelerated in the presence of selective tyrosine kinase inhibitors. Tonic inhibition of the PMCA was attenuated in cells expressing a dominant-negative construct or shRNA directed to message for the SFKs Lck or Fyn, but not Src. SFKs did not appear to phosphorylate the PMCA directly but instead activated focal adhesion kinase (FAK). Expression of constitutively active FAK enhanced and dominant-negative or shRNA knockdown of FAK attenuated tonic inhibition. Antisense knockdown of PMCA isoform 4 removed tonic inhibition of Ca(2+) clearance, indicating that FAK acts on PMCA4. The hyaluronan receptor CD44 activates SFK-FAK signaling cascades and is expressed in sensory neurons. Treating neurons with a CD44-blocking antibody or short hyaluronan oligosaccharides, which are produced during injury and displace macromolecular hyaluronan from CD44, attenuated tonic PMCA inhibition. Ca(2+)-activated K(+) channels mediate a slow afterhyperpolarization in sensory neurons that was inhibited by tyrosine kinase inhibitors and enhanced by knockdown of PMCA4. Thus, we describe a novel kinase cascade in sensory neurons that enables the extracellular matrix to alter Ca(2+) signals by modulating PMCA-mediated Ca(2+) clearance. This signaling pathway may influence the excitability of sensory neurons following injury.

  15. Dynamics of Population Activity in Rat Sensory Cortex: Network Correlations Predict Anatomical Arrangement and Information Content

    PubMed Central

    Sabri, Mohammad Mahdi; Adibi, Mehdi; Arabzadeh, Ehsan

    2016-01-01

    To study the spatiotemporal dynamics of neural activity in a cortical population, we implanted a 10 × 10 microelectrode array in the vibrissal cortex of urethane-anesthetized rats. We recorded spontaneous neuronal activity as well as activity evoked in response to sustained and brief sensory stimulation. To quantify the temporal dynamics of activity, we computed the probability distribution function (PDF) of spiking on one electrode given the observation of a spike on another. The spike-triggered PDFs quantified the strength, temporal delay, and temporal precision of correlated activity across electrodes. Nearby cells showed higher levels of correlation at short delays, whereas distant cells showed lower levels of correlation, which tended to occur at longer delays. We found that functional space built based on the strength of pairwise correlations predicted the anatomical arrangement of electrodes. Moreover, the correlation profile of electrode pairs during spontaneous activity predicted the “signal” and “noise” correlations during sensory stimulation. Finally, mutual information analyses revealed that neurons with stronger correlations to the network during spontaneous activity, conveyed higher information about the sensory stimuli in their evoked response. Given the 400-μm-distance between adjacent electrodes, our functional quantifications unravel the spatiotemporal dynamics of activity among nearby and distant cortical columns. PMID:27458347

  16. Molecular correlates of cortical network modulation by long-term sensory experience in the adult rat barrel cortex

    PubMed Central

    Vallès, Astrid; Granic, Ivica; De Weerd, Peter; Martens, Gerard J.M.

    2014-01-01

    Modulation of cortical network connectivity is crucial for an adaptive response to experience. In the rat barrel cortex, long-term sensory stimulation induces cortical network modifications and neuronal response changes of which the molecular basis is unknown. Here, we show that long-term somatosensory stimulation by enriched environment up-regulates cortical expression of neuropeptide mRNAs and down-regulates immediate-early gene (IEG) mRNAs specifically in the barrel cortex, and not in other brain regions. The present data suggest a central role of neuropeptides in the fine-tuning of sensory cortical circuits by long-term experience. PMID:25171421

  17. Synaptobrevin I mediates exocytosis of CGRP from sensory neurons and inhibition by botulinum toxins reflects their anti-nociceptive potential.

    PubMed

    Meng, Jianghui; Wang, Jiafu; Lawrence, Gary; Dolly, J Oliver

    2007-08-15

    Calcitonin-gene-related peptide (CGRP), a potent vasodilator that mediates inflammatory pain, is elevated in migraine; nevertheless, little is known about its release from sensory neurons. In this study, CGRP was found to occur in the majority of neurons from rat trigeminal ganglia, together with the three exocytotic SNAREs [SNAP25, syntaxin 1 and the synaptobrevin (Sbr, also known as VAMP) isoforms] and synaptotagmin. Ca(2+)-dependent CGRP release was evoked with K(+)-depolarisation and, to lower levels, by capsaicin or bradykinin from neurons that contain the vanilloid receptor 1 and/or bradykinin receptor 2. Botulinum neurotoxin (BoNT) type A cleaved SNAP25 and inhibited release triggered by K(+) > bradykinin > capsaicin. Unlike BoNT type D, BoNT type B did not affect exocytosis, even though the neurons possess its receptor and Sbr II and Sbr III got proteolysed (I is resistant in rat) but, in mouse neurons, it additionally cleaved Sbr I and blocked transmitter release. Sbr I and II were found in CGRP-containing vesicles, and each was shown to separately form a SNARE complex. These new findings, together with punctate staining of Sbr I and CGRP in neurites, implicate isoform Sbr I in exocytosis from large dense-core vesicles together with SNAP25 (also, probably, syntaxin 1 because BoNT type C1 caused partial cleavage and inhibition); this differs from Sbr-II-dependent release of transmitters from small synaptic vesicles. Such use of particular Sbr isoform(s) by different neurons raises the functional implications for other cells previously unrecognised.

  18. Anti-Hu associated paraneoplastic sensory neuronopathy with upper motor neurone involvement.

    PubMed

    Ogawa, M; Nishie, M; Kurahashi, K; Kaimori, M; Wakabayashi, K

    2004-07-01

    Paraneoplastic neurological syndrome is characterised by neuronal degeneration with lymphocytic infiltration in various regions of the central and peripheral nervous systems. Motor neurone symptoms may occur as a remote effect of malignancy, and have been considered because of the involvement of lower motor neurones. A case is reported of an 80 year old woman suffering from paraneoplastic sensory neuronopathy with anti-Hu antibody. Postmortem examination showed adenocarcinoma of the gall bladder and small cell carcinoma of the duodenum. Neuronal loss with lymphocytic infiltration was found in the dorsal root ganglia, brain stem, and cerebellum. Despite the absence of upper motor neurone signs, there was severe loss of Betz cells and degeneration of the bilateral pyramidal tracts. To our knowledge, this is the first demonstration of upper motor neurone involvement in anti-Hu associated paraneoplatic syndrome.

  19. Sensory deprivation increases phagocytosis of adult-born neurons by activated microglia in the olfactory bulb.

    PubMed

    Denizet, Marie; Cotter, Laurent; Lledo, Pierre-Marie; Lazarini, Françoise

    2017-02-01

    The olfactory bulb (OB) is a highly plastic structure that can change organizational networks depending on environmental inputs in adult mammals. Particularly, in rodents, adult neurogenesis underlies plastic changes in the OB circuitry by continuously adding new interneurons to the network. We addressed the question of whether microglia, the immune cells of the brain, were involved in pruning OB neurons. Using lentiviral labeling of neurons in neonatal or adult mice and confocal analysis, we showed that microglia engulfed parts of neonatal-born and adult-born neurons in the healthy OB. We demonstrated that OB deafferentation by Dichlobenil administration induced sensory deprivation. It also increased phagocytosis of adult-born, but not neonatal-born neurons, by activated microglia. Conversely, intranasal lipopolysaccharide administration induced activation of microglia but changed neither adult neurogenesis nor olfaction. Our data reveal that steady-state microglia eliminate adult-born neurons and their synapses in both healthy and sensory deprived OBs, thereby adapting neuronal connections to the sensory experience.

  20. MeCP2 regulates activity-dependent transcriptional responses in olfactory sensory neurons

    PubMed Central

    Lee, Wooje; Yun, Jung-Mi; Woods, Rima; Dunaway, Keith; Yasui, Dag H.; Lasalle, Janine M.; Gong, Qizhi

    2014-01-01

    During postnatal development, neuronal activity controls the remodeling of initially imprecise neuronal connections through the regulation of gene expression. MeCP2 binds to methylated DNA and modulates gene expression during neuronal development and MECP2 mutation causes the autistic disorder Rett syndrome. To investigate a role for MeCP2 in neuronal circuit refinement and to identify activity-dependent MeCP2 transcription regulations, we leveraged the precise organization and accessibility of olfactory sensory axons to manipulation of neuronal activity through odorant exposure in vivo. We demonstrate that olfactory sensory axons failed to develop complete convergence when Mecp2 is deficient in olfactory sensory neurons (OSNs) in an otherwise wild-type animal. Furthermore, we demonstrate that expression of selected adhesion genes was elevated in Mecp2-deficient glomeruli, while acute odor stimulation in control mice resulted in significantly reduced MeCP2 binding to these gene loci, correlating with increased expression. Thus, MeCP2 is required for both circuitry refinement and activity-dependent transcriptional responses in OSNs. PMID:25008110

  1. P2X3 and TRPV1 functionally interact and mediate sensitization of trigeminal sensory neurons

    PubMed Central

    Saloman, Jami L.; Chung, Man-Kyo; Ro, Jin Y.

    2012-01-01

    Musculoskeletal pain conditions, particularly those associated with temporomandibular joint and muscle disorders (TMD) affect a large percentage of the population. Identifying mechanisms underlying hyperalgesia could contribute to the development of new treatment strategies for the management of TMD and other muscle pain conditions. In this study, we provide evidence of functional interactions between two ligand-gated channels, P2X3 and TRPV1, in trigeminal sensory neurons, and propose that the interactions serve as an underlying mechanism for the development of mechanical hyperalgesia. Mechanical sensitivity of the masseter muscle was assessed in lightly anesthetized rats via an electronic anesthesiometer (Ro et al., 2009). Direct intramuscular injection of a selective P2X3 agonist, αβmeATP, induced a dose- and time-dependent hyperalgesia. Mechanical sensitivity in the contralateral muscle was unaffected suggesting local P2X3 mediate the hyperalgesia. Anesthetizing the overlying skin had no effect on αβmeATP-induced hyperalgesia confirming the contribution of P2X3 from muscle. Importantly, the αβmeATP-induced hyperalgesia was prevented by pretreatment of the muscle with a TRPV1 antagonist, AMG9810. P2X3 was co-expressed with TRPV1 in masseter muscle afferents confirming the possibility for intracellular interactions. Additionally, in a subpopulation of P2X3/TRPV1 positive neurons, capsaicin-induced Ca2+ transients were significantly amplified following P2X3 activation. Finally, activation of P2X3 induced phosphorylation of serine, but not threonine, residues in TRPV1 in trigeminal ganglia cultures. Significant phosphorylation was observed at 15 min, the time point at which behavioral hyperalgesia was prominent. Previously, activation of either P2X3 or TRPV1 had been independently implicated in the development of mechanical hyperalgesia. Our data propose P2X3 and TRPV1 interact in a facilitatory manner, which could contribute to the peripheral sensitization

  2. Redox and Nitric Oxide-Mediated Regulation of Sensory Neuron Ion Channel Function

    PubMed Central

    2015-01-01

    Abstract Significance: Reactive oxygen and nitrogen species (ROS and RNS, respectively) can intimately control neuronal excitability and synaptic strength by regulating the function of many ion channels. In peripheral sensory neurons, such regulation contributes towards the control of somatosensory processing; therefore, understanding the mechanisms of such regulation is necessary for the development of new therapeutic strategies and for the treatment of sensory dysfunctions, such as chronic pain. Recent Advances: Tremendous progress in deciphering nitric oxide (NO) and ROS signaling in the nervous system has been made in recent decades. This includes the recognition of these molecules as important second messengers and the elucidation of their metabolic pathways and cellular targets. Mounting evidence suggests that these targets include many ion channels which can be directly or indirectly modulated by ROS and NO. However, the mechanisms specific to sensory neurons are still poorly understood. This review will therefore summarize recent findings that highlight the complex nature of the signaling pathways involved in redox/NO regulation of sensory neuron ion channels and excitability; references to redox mechanisms described in other neuron types will be made where necessary. Critical Issues: The complexity and interplay within the redox, NO, and other gasotransmitter modulation of protein function are still largely unresolved. Issues of specificity and intracellular localization of these signaling cascades will also be addressed. Future Directions: Since our understanding of ROS and RNS signaling in sensory neurons is limited, there is a multitude of future directions; one of the most important issues for further study is the establishment of the exact roles that these signaling pathways play in pain processing and the translation of this understanding into new therapeutics. Antioxid. Redox Signal. 22, 486–504. PMID:24735331

  3. Informational basis of sensory adaptation: entropy and single-spike efficiency in rat barrel cortex.

    PubMed

    Adibi, Mehdi; Clifford, Colin W G; Arabzadeh, Ehsan

    2013-09-11

    We showed recently that exposure to whisker vibrations enhances coding efficiency in rat barrel cortex despite increasing correlations in variability (Adibi et al., 2013). Here, to understand how adaptation achieves this improvement in sensory representation, we decomposed the stimulus information carried in neuronal population activity into its fundamental components in the framework of information theory. In the context of sensory coding, these components are the entropy of the responses across the entire stimulus set (response entropy) and the entropy of the responses conditional on the stimulus (conditional response entropy). We found that adaptation decreased response entropy and conditional response entropy at both the level of single neurons and the pooled activity of neuronal populations. However, the net effect of adaptation was to increase the mutual information because the drop in the conditional entropy outweighed the drop in the response entropy. The information transmitted by a single spike also increased under adaptation. As population size increased, the information content of individual spikes declined but the relative improvement attributable to adaptation was maintained.

  4. The formation of the superior and jugular ganglia: insights into the generation of sensory neurons by the neural crest.

    PubMed

    Thompson, Hannah; Blentic, Aida; Watson, Sheona; Begbie, Jo; Graham, Anthony

    2010-02-01

    The superior and jugular ganglia (S/JG) are the proximal ganglia of the IXth and Xth cranial nerves and the sensory neurons of these ganglia are neural crest derived. However, it has been unclear the extent to which their differentiation resembles that of the Dorsal Root Ganglia (DRGs). In the DRGs, neural crest cells undergo neuronal differentiation just after the onset of migration and there is evidence suggesting that these cells are pre-specified towards a sensory fate. We have analysed sensory neuronal differentiation in the S/JG. We show, in keeping with previous studies, that neuronal differentiation initiates long after the cessation of neural crest migration. We also find no evidence for the existence of migratory neural crest cells pre-specified towards a sensory phenotype prior to ganglion formation. Rather our results suggest that sensory neuronal differentiation in the S/JG is the result of localised spatiotemporal cues.

  5. Cracking Taste Codes by Tapping into Sensory Neuron Impulse Traffic

    PubMed Central

    Frank, Marion E.; Lundy, Robert F.; Contreras, Robert J.

    2008-01-01

    Insights into the biological basis for mammalian taste quality coding began with electrophysiological recordings from “taste” nerves and this technique continues to produce essential information today. Chorda tympani (geniculate ganglion) neurons, which are particularly involved in taste quality discrimination, are specialists or generalists. Specialists respond to stimuli characterized by a single taste quality as defined by behavioral cross-generalization in conditioned taste tests. Generalists respond to electrolytes that elicit multiple aversive qualities. Na+-salt (N) specialists in rodents and sweet-stimulus (S) specialists in multiple orders of mammals are well-characterized. Specialists are associated with species’ nutritional needs and their activation is known to be malleable by internal physiological conditions and contaminated external caloric sources. S specialists, associated with the heterodimeric G-protein coupled receptor: T1R, and N specialists, associated with the epithelial sodium channel: ENaC, are consistent with labeled line coding from taste bud to afferent neuron. Yet, S-specialist neurons and behavior are less specific thanT1R2-3 in encompassing glutamate and E generalist neurons are much less specific than a candidate, PDK TRP channel, sour receptor in encompassing salts and bitter stimuli. Specialist labeled lines for nutrients and generalist patterns for aversive electrolytes may be transmitting taste information to the brain side by side. However, specific roles of generalists in taste quality coding may be resolved by selecting stimuli and stimulus levels found in natural situations. T2Rs, participating in reflexes via the glossopharynygeal nerve, became highly diversified in mammalian phylogenesis as they evolved to deal with dangerous substances within specific environmental niches. Establishing the information afferent neurons traffic to the brain about natural taste stimuli imbedded in dynamic complex mixtures will

  6. Trafficking regulates the subcellular distribution of voltage-gated sodium channels in primary sensory neurons.

    PubMed

    Bao, Lan

    2015-09-30

    Voltage-gated sodium channels (Navs) comprise at least nine pore-forming α subunits. Of these, Nav1.6, Nav1.7, Nav1.8 and Nav1.9 are the most frequently studied in primary sensory neurons located in the dorsal root ganglion and are mainly localized to the cytoplasm. A large pool of intracellular Navs raises the possibility that changes in Nav trafficking could alter channel function. The molecular mediators of Nav trafficking mainly consist of signals within the Navs themselves, interacting proteins and extracellular factors. The surface expression of Navs is achieved by escape from the endoplasmic reticulum and proteasome degradation, forward trafficking and plasma membrane anchoring, and it is also regulated by channel phosphorylation and ubiquitination in primary sensory neurons. Axonal transport and localization of Navs in afferent fibers involves the motor protein KIF5B and scaffold proteins, including contactin and PDZ domain containing 2. Localization of Nav1.6 to the nodes of Ranvier in myelinated fibers of primary sensory neurons requires node formation and the submembrane cytoskeletal protein complex. These findings inform our understanding of the molecular and cellular mechanisms underlying Nav trafficking in primary sensory neurons.

  7. Calcium-activated chloride currents in olfactory sensory neurons from mice lacking bestrophin-2.

    PubMed

    Pifferi, Simone; Dibattista, Michele; Sagheddu, Claudia; Boccaccio, Anna; Al Qteishat, Ahmed; Ghirardi, Filippo; Tirindelli, Roberto; Menini, Anna

    2009-09-01

    Olfactory sensory neurons use a chloride-based signal amplification mechanism to detect odorants. The binding of odorants to receptors in the cilia of olfactory sensory neurons activates a transduction cascade that involves the opening of cyclic nucleotide-gated channels and the entry of Ca(2+) into the cilia. Ca(2+) activates a Cl(-) current that produces an efflux of Cl(-) ions and amplifies the depolarization. The molecular identity of Ca(2+)-activated Cl(-) channels is still elusive, although some bestrophins have been shown to function as Ca(2+)-activated Cl(-) channels when expressed in heterologous systems. In the olfactory epithelium, bestrophin-2 (Best2) has been indicated as a candidate for being a molecular component of the olfactory Ca(2+)-activated Cl(-) channel. In this study, we have analysed mice lacking Best2. We compared the electrophysiological responses of the olfactory epithelium to odorant stimulation, as well as the properties of Ca(2+)-activated Cl(-) currents in wild-type (WT) and knockout (KO) mice for Best2. Our results confirm that Best2 is expressed in the cilia of olfactory sensory neurons, while odorant responses and Ca(2+)-activated Cl(-) currents were not significantly different between WT and KO mice. Thus, Best2 does not appear to be the main molecular component of the olfactory channel. Further studies are required to determine the function of Best2 in the cilia of olfactory sensory neurons.

  8. Calcium-activated chloride currents in olfactory sensory neurons from mice lacking bestrophin-2

    PubMed Central

    Pifferi, Simone; Dibattista, Michele; Sagheddu, Claudia; Boccaccio, Anna; Al Qteishat, Ahmed; Ghirardi, Filippo; Tirindelli, Roberto; Menini, Anna

    2009-01-01

    Olfactory sensory neurons use a chloride-based signal amplification mechanism to detect odorants. The binding of odorants to receptors in the cilia of olfactory sensory neurons activates a transduction cascade that involves the opening of cyclic nucleotide-gated channels and the entry of Ca2+ into the cilia. Ca2+ activates a Cl− current that produces an efflux of Cl− ions and amplifies the depolarization. The molecular identity of Ca2+-activated Cl− channels is still elusive, although some bestrophins have been shown to function as Ca2+-activated Cl− channels when expressed in heterologous systems. In the olfactory epithelium, bestrophin-2 (Best2) has been indicated as a candidate for being a molecular component of the olfactory Ca2+-activated Cl− channel. In this study, we have analysed mice lacking Best2. We compared the electrophysiological responses of the olfactory epithelium to odorant stimulation, as well as the properties of Ca2+-activated Cl− currents in wild-type (WT) and knockout (KO) mice for Best2. Our results confirm that Best2 is expressed in the cilia of olfactory sensory neurons, while odorant responses and Ca2+-activated Cl− currents were not significantly different between WT and KO mice. Thus, Best2 does not appear to be the main molecular component of the olfactory channel. Further studies are required to determine the function of Best2 in the cilia of olfactory sensory neurons. PMID:19622610

  9. Intrinsic frequency response patterns in mechano-sensory neurons of the leech.

    PubMed

    Fischer, Linda; Scherbarth, Frank; Chagnaud, Boris; Felmy, Felix

    2017-07-15

    Animals employ mechano-sensory systems to detect and explore their environment. Mechano-sensation encompasses stimuli such as constant pressure, surface movement or vibrations at various intensities that need to be segregated in the central nervous system. Besides different receptor structures, sensory filtering via intrinsic response properties could provide a convenient way to solve this problem. In leech, three major mechano-sensory cell types can be distinguished, according to their stimulus sensitivity, as nociceptive, pressure and touch cells. Using intracellular recordings, we show that the different mechano-sensory neuron classes in Hirudo medicinalis differentially respond supra-threshold to distinct frequencies of sinusoidal current injections between 0.2 and 20 Hz. Nociceptive cells responded with a low-pass filter characteristic, pressure cells as high-pass filters and touch cells as an intermediate band-pass filter. Each class of mechano-sensory neurons is thus intrinsically tuned to a specific frequency range of voltage oscillation that could help segregate mechano-sensory information centrally. © 2017. Published by The Company of Biologists Ltd.

  10. Intrinsic frequency response patterns in mechano-sensory neurons of the leech

    PubMed Central

    Fischer, Linda; Scherbarth, Frank; Chagnaud, Boris

    2017-01-01

    ABSTRACT Animals employ mechano-sensory systems to detect and explore their environment. Mechano-sensation encompasses stimuli such as constant pressure, surface movement or vibrations at various intensities that need to be segregated in the central nervous system. Besides different receptor structures, sensory filtering via intrinsic response properties could provide a convenient way to solve this problem. In leech, three major mechano-sensory cell types can be distinguished, according to their stimulus sensitivity, as nociceptive, pressure and touch cells. Using intracellular recordings, we show that the different mechano-sensory neuron classes in Hirudo medicinalis differentially respond supra-threshold to distinct frequencies of sinusoidal current injections between 0.2 and 20 Hz. Nociceptive cells responded with a low-pass filter characteristic, pressure cells as high-pass filters and touch cells as an intermediate band-pass filter. Each class of mechano-sensory neurons is thus intrinsically tuned to a specific frequency range of voltage oscillation that could help segregate mechano-sensory information centrally. PMID:28546342

  11. Sensory defects in Necdin deficient mice result from a loss of sensory neurons correlated within an increase of developmental programmed cell death

    PubMed Central

    Andrieu, David; Meziane, Hamid; Marly, Fabienne; Angelats, Corinne; Fernandez, Pierre-Alain; Muscatelli, Françoise

    2006-01-01

    Background The human NECDIN gene is involved in a neurodevelopmental disorder, Prader-Willi syndrome (PWS). Previously we reported a mouse Necdin knock-out model with similar defects to PWS patients. Despite the putative roles attributed to Necdin, mainly from in vitro studies, its in vivo function remains unclear. In this study, we investigate sensory-motor behaviour in Necdin deficient mice. We reveal cellular defects and analyse their cause. Results We report sensory differences in Necdin deficient mice compared to wild type animals. These differences led us to investigate sensory neuron development in Necdin deficient mouse embryos. First, we describe the expression pattern of Necdin in developing DRGs and report a reduction of one-third in specified sensory neurons in dorsal roots ganglia and show that this neuronal loss is achieved by E13.5, when DRGs sensory neurons are specified. In parallel, we observed an increase of 41% in neuronal apoptosis during the wave of naturally occurring cell death at E12.5. Since it is assumed that Necdin is a P75NTR interactor, we looked at the P75NTR-expressing cell population in Necdin knock-out embryos. Unexpectedly, Necdin loss of function has no effect on p75NTR expressing neurons suggesting no direct genetic interaction between Necdin and P75NTR in this context. Although we exclude a role of Necdin in axonal outgrowth from spinal sensory neurons in early developmental stages; such a role could occur later in neuronal differentiation. Finally we also exclude an anti-proliferative role of Necdin in developing sensory neurons. Conclusion Overall, our data show clearly that, in early development of the nervous system, Necdin is an anti-apoptotic or survival factor. PMID:17116257

  12. Phasic activation of the locus coeruleus enhances responses of primary sensory cortical neurons to peripheral receptive field stimulation.

    PubMed

    Waterhouse, B D; Moises, H C; Woodward, D J

    1998-04-20

    In the present study we examined the effects of phasic activation of the nucleus locus coeruleus (LC) on transmission of somatosensory information to the rat cerebral cortex. The rationale for this investigation was based on earlier findings that local microiontophoretic application of the putative LC transmitter, norepinephrine (NE), had facilitating actions on cortical neuronal responses to excitatory and inhibitory synaptic stimuli and more recent microdialysis experiments that have demonstrated increases in cortical levels of NE following phasic or tonic activation of LC. Glass micropipets were used to record the extracellular activity of single neurons in the somatosensory cortex of halothane-anesthetized rats. Somatosensory afferent pathways were activated by threshold level mechanical stimulation of the glabrous skin on the contralateral forepaw. Poststimulus time histograms were used to quantitate cortical neuronal responses before and at various time intervals after preconditioning burst activation of the ipsilateral LC. Excitatory and postexcitatory inhibitory responses to forepaw stimulation were enhanced when preceded by phasic activation of LC at conditioning intervals of 200-500 ms. These effects were anatomically specific in that they were only observed upon stimulation of brainstem sites close to (>150 micron) or within LC and were pharmacologically specific in that they were not consistently observed in animals where the LC-NE system had been disrupted by 6-OHDA pretreatment. Overall, these data suggest that following phasic activation of the LC efferent system, the efficacy of signal transmission through sensory networks in mammalian brain is enhanced.

  13. T-type calcium channels cause bursts of spikes in motor but not sensory thalamic neurons during mimicry of natural patterns of synaptic input.

    PubMed

    Kim, Haram R; Hong, Su Z; Fiorillo, Christopher D

    2015-01-01

    Although neurons within intact nervous systems can be classified as 'sensory' or 'motor,' it is not known whether there is any general distinction between sensory and motor neurons at the cellular or molecular levels. Here, we extend and test a theory according to which activation of certain subtypes of voltage-gated ion channel (VGC) generate patterns of spikes in neurons of motor systems, whereas VGC are proposed to counteract patterns in sensory neurons. We previously reported experimental evidence for the theory from visual thalamus, where we found that T-type calcium channels (TtCCs) did not cause bursts of spikes but instead served the function of 'predictive homeostasis' to maximize the causal and informational link between retinogeniculate excitation and spike output. Here, we have recorded neurons in brain slices from eight sensory and motor regions of rat thalamus while mimicking key features of natural excitatory and inhibitory post-synaptic potentials. As predicted by theory, TtCC did cause bursts of spikes in motor thalamus. TtCC-mediated responses in motor thalamus were activated at more hyperpolarized potentials and caused larger depolarizations with more spikes than in visual and auditory thalamus. Somatosensory thalamus is known to be more closely connected to motor regions relative to auditory and visual thalamus, and likewise the strength of its TtCC responses was intermediate between these regions and motor thalamus. We also observed lower input resistance, as well as limited evidence of stronger hyperpolarization-induced ('H-type') depolarization, in nuclei closer to motor output. These findings support our theory of a specific difference between sensory and motor neurons at the cellular level.

  14. Neuronal intrinsic properties shape naturally evoked sensory inputs in the dorsal horn of the spinal cord

    PubMed Central

    Reali, Cecilia; Russo, Raúl E.

    2013-01-01

    Intrinsic electrophysiological properties arising from specific combinations of voltage-gated channels are fundamental for the performance of small neural networks in invertebrates, but their role in large-scale vertebrate circuits remains controversial. Although spinal neurons have complex intrinsic properties, some tasks produce high-conductance states that override intrinsic conductances, minimizing their contribution to network function. Because the detection and coding of somato-sensory information at early stages probably involves a relatively small number of neurons, we speculated that intrinsic electrophysiological properties are likely involved in the processing of sensory inputs by dorsal horn neurons (DHN). To test this idea, we took advantage of an integrated spinal cord–hindlimbs preparation from turtles allowing the combination of patch-clamp recordings of DHN embedded in an intact network, with accurate control of the extracellular milieu. We found that plateau potentials and low threshold spikes (LTS) -mediated by L- and T-type Ca2+channels, respectively- generated complex dynamics by interacting with naturally evoked synaptic potentials. Inhibitory receptive fields could be changed in sign by activation of the LTS. On the other hand, the plateau potential transformed sensory signals in the time domain by generating persistent activity triggered on and off by brief sensory inputs and windup of the response to repetitive sensory stimulation. Our findings suggest that intrinsic properties dynamically shape sensory inputs and thus represent a major building block for sensory processing by DHN. Intrinsic conductances in DHN appear to provide a mechanism for plastic phenomena such as dynamic receptive fields and sensitization to pain. PMID:24399934

  15. Relationship between electrophysiological signature and defined sensory modality of trigeminal ganglion neurons in vivo.

    PubMed

    Boada, M Danilo

    2013-02-01

    The trigeminal ganglia (TG) innervate a heterogeneous set of highly sensitive and exposed tissues. Weak, innocuous stimuli can evoke pain as a normal response in some areas such as the cornea. This observation implies, however, the capability of low-threshold mechanoreceptors, inducing pain in the normal condition. To clarify this matter, the present study correlates the electrical signature (both fiber conduction velocity and somatic electrical properties) with receptor field, mechanical threshold, and temperature responsiveness of sensory afferents innervating tissues with dissimilar sensitivity (skin vs. cornea) in the trigeminal domain. Intracellular recordings were obtained in vivo from 148 neurons of the left TG of 62 mice. In 111 of these neurons, the peripheral receptor field was successfully localized: 96 of them innervated the hairy skin, while the remaining 15 innervated the cornea. The electrical signature was defined and peripheral responses correlated with tissue target. No high threshold neurons were found in the cornea. Moreover, the electrical signature of corneal afferents resembles nociceptive neurons in the skin. TG skin afferents showed similar membrane electrical signature and sensory modality as skin afferents from dorsal root ganglion, although TG afferents exhibited a shorter duration of afterhyperpolarization then those previously described in dorsal root ganglion. These data suggest than new or different ways to classify and study TG sensory neurons may be required.

  16. Transient receptor potential channels in sensory neurons are targets of the antimycotic agent clotrimazole.

    PubMed

    Meseguer, Victor; Karashima, Yuji; Talavera, Karel; D'Hoedt, Dieter; Donovan-Rodríguez, Tansy; Viana, Felix; Nilius, Bernd; Voets, Thomas

    2008-01-16

    Clotrimazole (CLT) is a widely used drug for the topical treatment of yeast infections of skin, vagina, and mouth. Common side effects of topical CLT application include irritation and burning pain of the skin and mucous membranes. Here, we provide evidence that transient receptor potential (TRP) channels in primary sensory neurons underlie these unwanted effects of CLT. We found that clinically relevant CLT concentrations activate heterologously expressed TRPV1 and TRPA1, two TRP channels that act as receptors of irritant chemical and/or thermal stimuli in nociceptive neurons. In line herewith, CLT stimulated a subset of capsaicin-sensitive and mustard oil-sensitive trigeminal neurons, and evoked nocifensive behavior and thermal hypersensitivity with intraplantar injection in mice. Notably, CLT-induced pain behavior was suppressed by the TRPV1-antagonist BCTC [(N-(-4-tertiarybutylphenyl)-4-(3-cholorpyridin-2-yl)tetrahydropyrazine-1(2H)-carboxamide)] and absent in TRPV1-deficient mice. In addition, CLT inhibited the cold and menthol receptor TRPM8, and blocked menthol-induced responses in capsaicin- and mustard oil-insensitive trigeminal neurons. The concentration for 50% inhibition (IC50) of inward TRPM8 current was approximately 200 nM, making CLT the most potent known TRPM8 antagonist and a useful tool to discriminate between TRPM8- and TRPA1-mediated responses. Together, our results identify TRP channels in sensory neurons as molecular targets of CLT, and offer means to develop novel CLT preparations with fewer unwanted sensory side effects.

  17. Neuronal correlates of sensory discrimination in the somatosensory cortex

    PubMed Central

    Hernández, Adrián; Zainos, Antonio; Romo, Ranulfo

    2000-01-01

    Monkeys are able to discriminate the difference in frequency between two periodic mechanical vibrations applied sequentially to the fingertips. It has been proposed that this ability is mediated by the periodicity of the responses in the quickly adapting (QA) neurons of the primary somatosensory cortex (S1), instead of the average firing rates. We recorded from QA neurons of S1 while monkeys performed the vibrotactile discrimination task. We found that the periodic mechanical vibrations can be represented both in the periodicity and in the firing rate responses to varying degrees across the QA neuronal population. We then computed neurometric functions by using both the periodicity and the firing rate and sought to determine which of these two measures is associated with the psychophysical performance. We found that neurometric thresholds based on the firing rate are very similar to the animal's psychometric thresholds whereas neurometric thresholds based on periodicity are far lower than those thresholds. These results indicate that an observer could solve this task with a precision similar to that of the monkey, based only on the firing rate produced during the stimulus periods. PMID:10811922

  18. Analysing neuronal correlates of the comparison of two sequentially presented sensory stimuli.

    PubMed Central

    Brody, Carlos D; Hernández, Adrián; Zainos, Antonio; Lemus, Luis; Romo, Ranulfo

    2002-01-01

    In a typical sequential sensory discrimination task, subjects are required to make a decision based on comparing a sensory stimulus against the memory trace left by a previous stimulus. What is the neuronal substrate for such comparisons and the resulting decisions? This question was studied by recording neuronal responses in a variety of cortical areas of awake monkeys (Macaca mulatta), trained to carry out a vibrotactile sequential discrimination task. We describe methods to analyse responses obtained during the comparison and decision phases of the task, and describe the resulting findings from recordings in secondary somatosensory cortical area (S2). A subset of neurons in S2 become highly correlated with the monkey's decision in the task. PMID:12626017

  19. Sensory, motor somatic, and autonomic neurons projecting to the porcine cremaster muscle.

    PubMed

    Botti, Maddalena; Minelli, Luisa Bo; Gazza, Ferdinando; Ragionieri, Luisa; Acone, Franca; Panu, Rino; Palmieri, Giovanni

    2006-10-01

    The location of sensory, somatic, and autonomic neurons projecting to the pig cremaster muscle (CM) was studied by means of the retrograde neuronal tracer Fast Blue (FB) technique. FB was randomly injected in the left CM of four impuberal pigs and serial sections of sensory and autonomic ganglia and spinal cord were examined under a fluorescence microscope. Additionally, some indications about the number and size of labeled neurons were given. Sensory pseudounipolar somata were located ipsilaterally in the L2-L6 and S1-S2 dorsal root ganglia, their total number ranging between 125 and 194, their mean diameter between 24 and 89 microm. Somatic multipolar motoneurons were located ipsilaterally in the L2-L4 neuromeres of the spinal cord, their total number ranging between 53 and 169, their mean diameter between 29 and 53 microm. Autonomic multipolar paravertebral ganglia neurons were located ipsilaterally from L1 to S4 and contralaterally from L2 to S2. Their total number ranged from 2,015 to 3,067 and their mean diameter between 25 and 55 microm. The multipolar caudal mesenteric ganglia neurons were located bilaterally, their total number ranging between 14 and 1,408 and their diameter from 22 to 39 microm. In two subjects only, multipolar neurons were also found ipsilaterally in the microganglia of pelvic plexus (2 and 13 neurons). Their mean diameter ranged between 28 and 54 microm. Our study documented that the CM-projecting neurons were located at different neural levels, with a predominance in the autonomic ganglia.

  20. Morphological Analysis of Drosophila Larval Peripheral Sensory Neuron Dendrites and Axons Using Genetic Mosaics

    PubMed Central

    Karim, M. Rezaul; Moore, Adrian W.

    2011-01-01

    Nervous system development requires the correct specification of neuron position and identity, followed by accurate neuron class-specific dendritic development and axonal wiring. Recently the dendritic arborization (DA) sensory neurons of the Drosophila larval peripheral nervous system (PNS) have become powerful genetic models in which to elucidate both general and class-specific mechanisms of neuron differentiation. There are four main DA neuron classes (I-IV)1. They are named in order of increasing dendrite arbor complexity, and have class-specific differences in the genetic control of their differentiation2-10. The DA sensory system is a practical model to investigate the molecular mechanisms behind the control of dendritic morphology11-13 because: 1) it can take advantage of the powerful genetic tools available in the fruit fly, 2) the DA neuron dendrite arbor spreads out in only 2 dimensions beneath an optically clear larval cuticle making it easy to visualize with high resolution in vivo, 3) the class-specific diversity in dendritic morphology facilitates a comparative analysis to find key elements controlling the formation of simple vs. highly branched dendritic trees, and 4) dendritic arbor stereotypical shapes of different DA neurons facilitate morphometric statistical analyses. DA neuron activity modifies the output of a larval locomotion central pattern generator14-16. The different DA neuron classes have distinct sensory modalities, and their activation elicits different behavioral responses14,16-20. Furthermore different classes send axonal projections stereotypically into the Drosophila larval central nervous system in the ventral nerve cord (VNC)21. These projections terminate with topographic representations of both DA neuron sensory modality and the position in the body wall of the dendritic field7,22,23. Hence examination of DA axonal projections can be used to elucidate mechanisms underlying topographic mapping7,22,23, as well as the wiring of a

  1. Morphological analysis of Drosophila larval peripheral sensory neuron dendrites and axons using genetic mosaics.

    PubMed

    Karim, M Rezaul; Moore, Adrian W

    2011-11-07

    Nervous system development requires the correct specification of neuron position and identity, followed by accurate neuron class-specific dendritic development and axonal wiring. Recently the dendritic arborization (DA) sensory neurons of the Drosophila larval peripheral nervous system (PNS) have become powerful genetic models in which to elucidate both general and class-specific mechanisms of neuron differentiation. There are four main DA neuron classes (I-IV)(1). They are named in order of increasing dendrite arbor complexity, and have class-specific differences in the genetic control of their differentiation(2-10). The DA sensory system is a practical model to investigate the molecular mechanisms behind the control of dendritic morphology(11-13) because: 1) it can take advantage of the powerful genetic tools available in the fruit fly, 2) the DA neuron dendrite arbor spreads out in only 2 dimensions beneath an optically clear larval cuticle making it easy to visualize with high resolution in vivo, 3) the class-specific diversity in dendritic morphology facilitates a comparative analysis to find key elements controlling the formation of simple vs. highly branched dendritic trees, and 4) dendritic arbor stereotypical shapes of different DA neurons facilitate morphometric statistical analyses. DA neuron activity modifies the output of a larval locomotion central pattern generator(14-16). The different DA neuron classes have distinct sensory modalities, and their activation elicits different behavioral responses(14,16-20). Furthermore different classes send axonal projections stereotypically into the Drosophila larval central nervous system in the ventral nerve cord (VNC)(21). These projections terminate with topographic representations of both DA neuron sensory modality and the position in the body wall of the dendritic field(7,22,23). Hence examination of DA axonal projections can be used to elucidate mechanisms underlying topographic mapping(7,22,23), as well as

  2. Modulatory Role of Sensory Innervation on Hair Follicle Stem Cell Progeny during Wound Healing of the Rat Skin

    PubMed Central

    Martínez-Martínez, Eduardo; Galván-Hernández, Claudio I.; Toscano-Márquez, Brenda; Gutiérrez-Ospina, Gabriel

    2012-01-01

    Background The bulge region of the hair follicle contains resident epithelial stem cells (SCs) that are activated and mobilized during hair growth and after epidermal wounding. However, little is known about the signals that modulate these processes. Clinical and experimental observations show that a reduced supply of sensory innervation is associated with delayed wound healing. Since axon terminals of sensory neurons are among the components of the bulge SC niche, we investigated whether these neurons are involved in the activation and mobilization of the hair stem cells during wound healing. Methodology/Principal Findings We used neonatal capsaicin treatment to reduce sensory terminals in the rat skin and performed morphometric analyses using design-based stereological methods. Epithelial proliferation was analyzed by quantifying the number of bromodeoxyuridine-labeled (BrdU+) nuclei in the epidermis and hair follicles. After wounding, the epidermis of capsaicin-treated rats presented fewer BrdU+ nuclei than in control rats. To assess SC progeny migration, we employed a double labeling protocol with iododeoxyuridine and chlorodeoxyuridine (IdU+/CldU+). The proportion of double-labeled cells was similar in the hair follicles of both groups at 32 h postwounding. IdU+/CldU+ cell proportion increased in the epidermis of control rats and decreased in treated rats at 61 h postwounding. The epidermal volume immunostained for keratin 6 was greater in treated rats at 61 h. Confocal microscopy analysis revealed that substance P (SP) and calcitonin gene-related peptide (CGRP) receptor immunoreactivity were both present in CD34+ and BrdU-retaining cells of the hair follicles. Conclusions/Significance Our results suggest that capsaicin denervation impairs SC progeny egress from the hair follicles, a circumstance associated with a greater epidermal activation. Altogether, these phenomena would explain the longer times for healing in denervated skin. Thus, sensory innervation

  3. TRPA1 contributes to specific mechanically activated currents and sensory neuron mechanical hypersensitivity

    PubMed Central

    Brierley, Stuart M; Castro, Joel; Harrington, Andrea M; Hughes, Patrick A; Page, Amanda J; Rychkov, Grigori Y; Blackshaw, L Ashley

    2011-01-01

    Abstract The mechanosensory role of TRPA1 and its contribution to mechanical hypersensitivity in sensory neurons remains enigmatic. We elucidated this role by recording mechanically activated currents in conjunction with TRPA1 over- and under-expression and selective pharmacology. First, we established that TRPA1 transcript, protein and functional expression are more abundant in smaller-diameter neurons than larger-diameter neurons, allowing comparison of two different neuronal populations. Utilising whole cell patch clamping, we applied calibrated displacements to neurites of dorsal root ganglion (DRG) neurons in short-term culture and recorded mechanically activated currents termed intermediately (IAMCs), rapidly (RAMCs) or slowly adapting (SAMCs). Trpa1 deletion (–/–) significantly reduced maximum IAMC amplitude by 43% in small-diameter neurons compared with wild-type (+/+) neurons. All other mechanically activated currents in small- and large-diameter Trpa1−/− neurons were unaltered. Seventy-three per cent of Trpa1+/+ small-diameter neurons responding to the TRPA1 agonist allyl-isothiocyanate (AITC) displayed IAMCs to neurite displacement, which were significantly enhanced after AITC addition. The TRPA1 antagonist HC-030031 significantly decreased Trpa1+/+ IAMC amplitudes, but only in AITC responsive neurons. Using a transfection system we also showed TRPA1 over-expression in Trpa1+/+ small-diameter neurons increases IAMC amplitude, an effect reversed by HC-030031. Furthermore, TRPA1 introduction into Trpa1−/− small-diameter neurons restored IAMC amplitudes to Trpa1+/+ levels, which was subsequently reversed by HC-030031. In summary our data demonstrate TRPA1 makes a contribution to normal mechanosensation in a specific subset of DRG neurons. Furthermore, they also provide new evidence illustrating mechanisms by which sensitisation or over-expression of TRPA1 enhances nociceptor mechanosensitivity. Overall, these findings suggest TRPA1 has the

  4. TRPA1 contributes to specific mechanically activated currents and sensory neuron mechanical hypersensitivity.

    PubMed

    Brierley, Stuart M; Castro, Joel; Harrington, Andrea M; Hughes, Patrick A; Page, Amanda J; Rychkov, Grigori Y; Blackshaw, L Ashley

    2011-07-15

    The mechanosensory role of TRPA1 and its contribution to mechanical hypersensitivity in sensory neurons remains enigmatic. We elucidated this role by recording mechanically activated currents in conjunction with TRPA1 over- and under-expression and selective pharmacology. First, we established that TRPA1 transcript, protein and functional expression are more abundant in smaller-diameter neurons than larger-diameter neurons, allowing comparison of two different neuronal populations. Utilising whole cell patch clamping, we applied calibrated displacements to neurites of dorsal root ganglion (DRG) neurons in short-term culture and recorded mechanically activated currents termed intermediately (IAMCs), rapidly (RAMCs) or slowly adapting (SAMCs). Trpa1 deletion (–/–) significantly reduced maximum IAMC amplitude by 43% in small-diameter neurons compared with wild-type (+/+) neurons. All other mechanically activated currents in small- and large-diameter Trpa1−/− neurons were unaltered. Seventy-three per cent of Trpa1+/+ small-diameter neurons responding to the TRPA1 agonist allyl-isothiocyanate (AITC) displayed IAMCs to neurite displacement, which were significantly enhanced after AITC addition. The TRPA1 antagonist HC-030031 significantly decreased Trpa1+/+ IAMC amplitudes, but only in AITC responsive neurons. Using a transfection system we also showed TRPA1 over-expression in Trpa1+/+ small-diameter neurons increases IAMC amplitude, an effect reversed by HC-030031. Furthermore, TRPA1 introduction into Trpa1−/− small-diameter neurons restored IAMC amplitudes to Trpa1+/+ levels, which was subsequently reversed by HC-030031. In summary our data demonstrate TRPA1 makes a contribution to normal mechanosensation in a specific subset of DRG neurons. Furthermore, they also provide new evidence illustrating mechanisms by which sensitisation or over-expression of TRPA1 enhances nociceptor mechanosensitivity. Overall, these findings suggest TRPA1 has the capacity to

  5. Human Induced Pluripotent Cell-Derived Sensory Neurons for Fate Commitment of Bone Marrow-Derived Schwann Cells: Implications for Remyelination Therapy.

    PubMed

    Cai, Sa; Han, Lei; Ao, Qiang; Chan, Ying-Shing; Shum, Daisy Kwok-Yan

    2017-02-01

    Strategies that exploit induced pluripotent stem cells (iPSCs) to derive neurons have relied on cocktails of cytokines and growth factors to bias cell-signaling events in the course of fate choice. These are often costly and inefficient, involving multiple steps. In this study, we took an alternative approach and selected 5 small-molecule inhibitors of key signaling pathways in an 8-day program to induce differentiation of human iPSCs into sensory neurons, reaching ≥80% yield in terms of marker proteins. Continuing culture in maintenance medium resulted in neuronal networks immunopositive for synaptic vesicle markers and vesicular glutamate transporters suggestive of excitatory neurotransmission. Subpopulations of the derived neurons were electrically excitable, showing tetrodotoxin-sensitive action potentials in patch-clamp experiments. Coculture of the derived neurons with rat Schwann cells under myelinating conditions resulted in upregulated levels of neuronal neuregulin 1 type III in conjunction with the phosphorylated receptors ErbB2 and ErbB3, consistent with amenability of the neuritic network to myelination. As surrogates of embryonic dorsal root ganglia neurons, the derived sensory neurons provided contact-dependent cues to commit bone marrow-derived Schwann cell-like cells to the Schwann cell fate. Our rapid and efficient induction protocol promises not only controlled differentiation of human iPSCs into sensory neurons, but also utility in the translation to a protocol whereby human bone marrow-derived Schwann cells become available for autologous transplantation and remyelination therapy. Stem Cells Translational Medicine 2017;6:369-381.

  6. Transcriptome Analysis of Chemically-Induced Sensory Neuron Ablation in Zebrafish

    PubMed Central

    Cox, Jane A.; Zhang, Bo; Pope, Holly M.; Voigt, Mark M.

    2016-01-01

    Peripheral glia are known to have a critical role in the initial response to axon damage and degeneration. However, little is known about the cellular responses of non-myelinating glia to nerve injury. In this study, we analyzed the transcriptomes of wild-type and mutant (lacking peripheral glia) zebrafish larvae that were treated with metronidazole. This treatment allowed us to conditionally and selectively ablate cranial sensory neurons whose axons are ensheathed only by non-myelinating glia. While transcripts representing over 27,000 genes were detected by RNAseq, only a small fraction (~1% of genes) were found to be differentially expressed in response to neuronal degeneration in either line at either 2 hrs or 5 hrs of metronidazole treatment. Analysis revealed that most expression changes (332 out of the total of 458 differentially expressed genes) occurred over a continuous period (from 2 to 5 hrs of metronidazole exposure), with a small number of genes showing changes limited to only the 2 hr (55 genes) or 5 hr (71 genes) time points. For genes with continuous alterations in expression, some of the most meaningful sets of enriched categories in the wild-type line were those involving the inflammatory TNF-alpha and IL6 signaling pathways, oxidoreductase activities and response to stress. Intriguingly, these changes were not observed in the mutant line. Indeed, cluster analysis indicated that the effects of metronidazole treatment on gene expression was heavily influenced by the presence or absence of glia, indicating that the peripheral non-myelinating glia play a significant role in the transcriptional response to sensory neuron degeneration. This is the first transcriptome study of metronidazole-induced neuronal death in zebrafish and the response of non-myelinating glia to sensory neuron degeneration. We believe this study provides important insight into the mechanisms by which non-myelinating glia react to neuronal death and degeneration in sensory

  7. Calcium-activated chloride channels in the apical region of mouse vomeronasal sensory neurons

    PubMed Central

    Dibattista, Michele; Amjad, Asma; Maurya, Devendra Kumar; Sagheddu, Claudia; Montani, Giorgia; Tirindelli, Roberto

    2012-01-01

    The rodent vomeronasal organ plays a crucial role in several social behaviors. Detection of pheromones or other emitted signaling molecules occurs in the dendritic microvilli of vomeronasal sensory neurons, where the binding of molecules to vomeronasal receptors leads to the influx of sodium and calcium ions mainly through the transient receptor potential canonical 2 (TRPC2) channel. To investigate the physiological role played by the increase in intracellular calcium concentration in the apical region of these neurons, we produced localized, rapid, and reproducible increases in calcium concentration with flash photolysis of caged calcium and measured calcium-activated currents with the whole cell voltage-clamp technique. On average, a large inward calcium-activated current of −261 pA was measured at −50 mV, rising with a time constant of 13 ms. Ion substitution experiments showed that this current is anion selective. Moreover, the chloride channel blockers niflumic acid and 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid partially inhibited the calcium-activated current. These results directly demonstrate that a large chloride current can be activated by calcium in the apical region of mouse vomeronasal sensory neurons. Furthermore, we showed by immunohistochemistry that the calcium-activated chloride channels TMEM16A/anoctamin1 and TMEM16B/anoctamin2 are present in the apical layer of the vomeronasal epithelium, where they largely colocalize with the TRPC2 transduction channel. Immunocytochemistry on isolated vomeronasal sensory neurons showed that TMEM16A and TMEM16B coexpress in the neuronal microvilli. Therefore, we conclude that microvilli of mouse vomeronasal sensory neurons have a high density of calcium-activated chloride channels that may play an important role in vomeronasal transduction. PMID:22732308

  8. Calcium-activated chloride channels in the apical region of mouse vomeronasal sensory neurons.

    PubMed

    Dibattista, Michele; Amjad, Asma; Maurya, Devendra Kumar; Sagheddu, Claudia; Montani, Giorgia; Tirindelli, Roberto; Menini, Anna

    2012-07-01

    The rodent vomeronasal organ plays a crucial role in several social behaviors. Detection of pheromones or other emitted signaling molecules occurs in the dendritic microvilli of vomeronasal sensory neurons, where the binding of molecules to vomeronasal receptors leads to the influx of sodium and calcium ions mainly through the transient receptor potential canonical 2 (TRPC2) channel. To investigate the physiological role played by the increase in intracellular calcium concentration in the apical region of these neurons, we produced localized, rapid, and reproducible increases in calcium concentration with flash photolysis of caged calcium and measured calcium-activated currents with the whole cell voltage-clamp technique. On average, a large inward calcium-activated current of -261 pA was measured at -50 mV, rising with a time constant of 13 ms. Ion substitution experiments showed that this current is anion selective. Moreover, the chloride channel blockers niflumic acid and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid partially inhibited the calcium-activated current. These results directly demonstrate that a large chloride current can be activated by calcium in the apical region of mouse vomeronasal sensory neurons. Furthermore, we showed by immunohistochemistry that the calcium-activated chloride channels TMEM16A/anoctamin1 and TMEM16B/anoctamin2 are present in the apical layer of the vomeronasal epithelium, where they largely colocalize with the TRPC2 transduction channel. Immunocytochemistry on isolated vomeronasal sensory neurons showed that TMEM16A and TMEM16B coexpress in the neuronal microvilli. Therefore, we conclude that microvilli of mouse vomeronasal sensory neurons have a high density of calcium-activated chloride channels that may play an important role in vomeronasal transduction.

  9. THE NEURONAL DISTRIBUTION OF CANNABINOID RECEPTOR TYPE 1 IN THE TRIGEMINAL GANGLION OF THE RAT

    PubMed Central

    PRICE, T. J.; HELESIC, G.; PARGHI, D.; HARGREAVES, K. M.; FLORES, C. M.

    2007-01-01

    Cannabinoid compounds have been shown to produce antinociception and antihyperalgesia by acting upon cannabinoid receptors located in both the CNS and the periphery. A potential mechanism by which cannabinoids could inhibit nociception in the periphery is the activation of cannabinoid receptors located on one or more classes of primary nociceptive neurons. To address this hypothesis, we evaluated the neuronal distribution of cannabinoid receptor type 1 (CB1) in the trigeminal ganglion (TG) of the adult rat through combined in situ hybridization (ISH) and immunohistochemistry (IHC). CB1 receptor mRNA was localized mainly to medium and large diameter neurons of the maxillary and mandibular branches of the TG. Consistent with this distribution, in a de facto nociceptive sensory neuron population that exhibited vanilloid receptor type 1 immunoreactivity, colocalization with CB1 mRNA was also sparse (<5%). Furthermore, very few neurons (approximately 5%) in the peptidergic (defined as calcitonin gene-related peptide- or substance P-immunoreactive) or the isolectin B4-binding sensory neuron populations contained CB1 mRNA. In contrast, and consistent with the neuron-size distribution for CB1, nearly 75% of CB1-positive neurons exhibited N52-immunoreactivity, a marker of myelinated axons. These results indicate that in the rat TG, CB1 receptors are expressed predominantly in neurons that are not thought to subserve nociceptive neurotransmission in the noninjured animal. Taken together with the absence of an above background in situ signal for CB2 mRNA in TG neurons, these findings suggest that the peripherally mediated antinociceptive effects of cannabinoids may involve either as yet unidentified receptors or interaction with afferent neuron populations that normally subserve non-nociceptive functions. PMID:12849749

  10. Current concepts of nociception: nociceptive molecular sensors in sensory neurons.

    PubMed

    Hwang, Sun Wook; Oh, Uhtaek

    2007-10-01

    A large number of channels that are in some way linked to sensory transduction including nociception have been discovered in recent years. This review summarizes newly discovered channels that are implicated in nociception. Furthermore, details are discussed with emphasis on their possible application to clinical use as analgesics. Studies with null mutant animals deficient in these channel genes reveal that the channels are indeed implicated in physiological as well as pathological nociception. Many transient receptor potential channels are thermosensors that detect cold, warm and hot temperatures. These channels are activated not only by natural chemicals such as capsaicin, menthol, and camphor, but by various inflammatory signaling pathways. The acid-sensing ion channel and P2X channel that detect extracellular acidosis and ATP are also implicated in some types of pain. Voltage-gated sodium or calcium channels draw attention because of their involvement in neuropathic pain.

  11. A Case-controlled Investigation of Pain Experience and Sensory Function in Neuronal Ceroid Lipofuscinosis

    PubMed Central

    Barney, Chantel C.; Hoch, John; Byiers, Breanne; Dimian, Adele; Symons, Frank J.

    2014-01-01

    Objectives This case-control study explored pain experience and expression among individuals with Neuronal Ceroid Lipofuscinosis (NCL) through parental report, tactile-sensory testing, and infrared thermography (IRT). Methods Individuals with NCL (n=8; M age= 14.8 years) and their unaffected siblings (n=8;M age 23.5 years) were characterized in terms of pain response to a brief tactile sensory test (light touch, Von Frey monofilament). During sensory testing, behavioral expression was measured using the Battens Observational Pain Scale (BOPS) and infrared thermography (IRT) was used to quantify changes in skin/eye temperature. Results Individuals with NCL experienced pain frequently and from multiple sources that negatively impacted their lives. Individuals with NCL were reactive to the sensory testing as indexed by significant increased IRT temperature change (p<.001). Across combined sensory conditions, individuals with NCL were significantly more reactive (BOPS total score) to sensory testing compared to siblings (p< .05). Similarly, IRT difference scores between sensory conditions revealed a significant increase in temperature for individuals with NCL compared to siblings (p<.001). Discussion Ongoing reported pain was a problem for the individuals with NCL in this sample. Increased pain expression during the repeated Von Frey filament suggests that the pathophysiology of the ongoing pain may be centrally mediated. PMID:25569218

  12. Correlation between Cortical State and Locus Coeruleus Activity: Implications for Sensory Coding in Rat Barrel Cortex

    PubMed Central

    Fazlali, Zeinab; Ranjbar-Slamloo, Yadollah; Adibi, Mehdi; Arabzadeh, Ehsan

    2016-01-01

    Cortical state modulates the background activity of cortical neurons, and their evoked response to sensory stimulation. Multiple mechanisms are involved in switching between cortical states including various neuromodulatory systems. Locus Coeruleus (LC) is one of the major neuromodulatory nuclei in the brainstem with widespread projections throughout the brain and modulates the activity of cells and networks. Here, we quantified the link between the LC spontaneous activity, cortical state and sensory processing in the rat vibrissal somatosensory “barrel” cortex (BC). We simultaneously recorded unit activity from LC and BC along with prefrontal electroencephalogram (EEG) while presenting brief whisker deflections under urethane anesthesia. The ratio of low to high frequency components of EEG (referred to as the L/H ratio) was employed to identify cortical state. We found that the spontaneous activity of LC units exhibited a negative correlation with the L/H ratio. Cross-correlation analysis revealed that changes in LC firing preceded changes in the cortical state: the correlation of the LC firing profile with the L/H ratio was maximal at an average lag of −1.2 s. We further quantified BC neuronal responses to whisker stimulation during the synchronized and desynchronized states. In the desynchronized state, BC neurons showed lower stimulus detection threshold, higher response fidelity, and shorter response latency. The most prominent change was observed in the late phase of BC evoked activity (100–400 ms post stimulus onset): almost every BC unit exhibited a greater late response during the desynchronized state. Categorization of the BC evoked responses based on LC activity (into high and low LC discharge rates) resulted in highly similar response profiles compared to categorization based on the cortical state (low and high L/H ratios). These findings provide evidence for the involvement of the LC neuromodulatory system in desynchronization of cortical state

  13. Exposure to Zinc Sulfate Results in Differential Effects on Olfactory Sensory Neuron Subtypes in Adult Zebrafish

    PubMed Central

    Hentig, James T.; Byrd-Jacobs, Christine A.

    2016-01-01

    Zinc sulfate is a known olfactory toxicant, although its specific effects on the olfactory epithelium of zebrafish are unknown. Olfactory organs of adult zebrafish were exposed to zinc sulfate and, after 2, 3, 5, 7, 10 or 14 days, fish were processed for histological, immunohistochemical, ultrastructural, and behavioral analyses. Severe morphological disruption of the olfactory organ was observed two days following zinc sulfate exposure, including fusion of lamellae, epithelial inflammation, and significant loss of anti-calretinin labeling. Scanning electron microscopy revealed the apical surface of the sensory region was absent of ciliated structures, but microvilli were still present. Behavioral analysis showed significant loss of the ability to perceive bile salts and some fish also had no response to amino acids. Over the next several days, olfactory organ morphology, epithelial structure, and anti-calretinin labeling returned to control-like conditions, although the ability to perceive bile salts remained lost until day 14. Thus, exposure to zinc sulfate results in rapid degeneration of the olfactory organ, followed by restoration of morphology and function within two weeks. Zinc sulfate appears to have a greater effect on ciliated olfactory sensory neurons than on microvillous olfactory sensory neurons, suggesting differential effects on sensory neuron subtypes. PMID:27589738

  14. Exposure to Zinc Sulfate Results in Differential Effects on Olfactory Sensory Neuron Subtypes in Adult Zebrafish.

    PubMed

    Hentig, James T; Byrd-Jacobs, Christine A

    2016-08-31

    Zinc sulfate is a known olfactory toxicant, although its specific effects on the olfactory epithelium of zebrafish are unknown. Olfactory organs of adult zebrafish were exposed to zinc sulfate and, after 2, 3, 5, 7, 10 or 14 days, fish were processed for histological, immunohistochemical, ultrastructural, and behavioral analyses. Severe morphological disruption of the olfactory organ was observed two days following zinc sulfate exposure, including fusion of lamellae, epithelial inflammation, and significant loss of anti-calretinin labeling. Scanning electron microscopy revealed the apical surface of the sensory region was absent of ciliated structures, but microvilli were still present. Behavioral analysis showed significant loss of the ability to perceive bile salts and some fish also had no response to amino acids. Over the next several days, olfactory organ morphology, epithelial structure, and anti-calretinin labeling returned to control-like conditions, although the ability to perceive bile salts remained lost until day 14. Thus, exposure to zinc sulfate results in rapid degeneration of the olfactory organ, followed by restoration of morphology and function within two weeks. Zinc sulfate appears to have a greater effect on ciliated olfactory sensory neurons than on microvillous olfactory sensory neurons, suggesting differential effects on sensory neuron subtypes.

  15. Combinatorial expression of TRPV channel proteins defines their sensory functions and subcellular localization in C. elegans neurons.

    PubMed

    Tobin, David M; Madsen, David M; Kahn-Kirby, Amanda; Peckol, Erin L; Moulder, Gary; Barstead, Robert; Maricq, Andres V; Bargmann, Cornelia I

    2002-07-18

    C. elegans OSM-9 is a TRPV channel protein involved in sensory transduction and adaptation. Here, we show that distinct sensory functions arise from different combinations of OSM-9 and related OCR TRPV proteins. Both OSM-9 and OCR-2 are essential for several forms of sensory transduction, including olfaction, osmosensation, mechanosensation, and chemosensation. In neurons that express both OSM-9 and OCR-2, tagged OCR-2 and OSM-9 proteins reside in sensory cilia and promote each other's localization to cilia. In neurons that express only OSM-9, tagged OSM-9 protein resides in the cell body and acts in sensory adaptation rather than sensory transduction. Thus, alternative combinations of TRPV proteins may direct different functions in distinct subcellular locations. Animals expressing the mammalian TRPV1 (VR1) channel in ASH nociceptor neurons avoid the TRPV1 ligand capsaicin, allowing selective, drug-inducible activation of a specific behavior.

  16. Primary sensory neuron-specific interference of TRPV1 signaling by adeno-associated virus-encoded TRPV1 peptide aptamer attenuates neuropathic pain

    PubMed Central

    Xiang, Hongfei; Liu, Zhen; Wang, Fei; Xu, Hao; Roberts, Christopher; Fischer, Gregory; Stucky, Cheryl L; Dean, Caron; Pan, Bin

    2017-01-01

    Background TRPV1 (transient receptor potential vanilloid subfamily member 1) is a pain signaling channel highly expressed in primary sensory neurons. Attempts for analgesia by systemic TRPV1 blockade produce undesirable side effects, such as hyperthermia and impaired heat pain sensation. One approach for TRPV1 analgesia is to target TRPV1 along the peripheral sensory pathway. Results For functional blockade of TRPV1 signaling, we constructed an adeno-associated virus (AAV) vector expressing a recombinant TRPV1 interfering peptide aptamer, derived from a 38mer tetrameric assembly domain (TAD), encompassing residues 735 to 772 of rat TRPV1, fused to the C-terminus of enhanced green fluorescent protein (EGFP). AAV-targeted sensory neurons expressing EGFP-TAD after vector injection into the dorsal root ganglia (DRG) revealed decreased inward calcium current and diminished intracellular calcium accumulation in response to capsaicin, compared to neurons of naïve or expressing EGFP alone. To examine the potential for treating neuropathic pain, AAV-EGFP-TAD was injected into fourth and fifth lumbar (L) DRGs of rats subjected to neuropathic pain by tibial nerve injury (TNI). Results showed that AAV-directed selective expression of EGFP-TAD in L4/L5 DRG neuron somata, and their peripheral and central axonal projections can limit TNI-induced neuropathic pain behavior, including hypersensitivity to heat and, to a less extent, mechanical stimulation. Conclusion Selective inhibition of TRPV1 activity in primary sensory neurons by DRG delivery of AAV-encoded analgesic interfering peptide aptamers is efficacious in attenuation of neuropathic pain. With further improvements of vector constructs and in vivo application, this approach might have the potential to develop as an alternative gene therapy strategy to treat chronic pain, especially heat hypersensitivity, without complications due to systemic TRPV1 blockade. PMID:28604222

  17. Sexually dimorphic control of gene expression in sensory neurons regulates decision-making behavior in C. elegans.

    PubMed

    Hilbert, Zoë A; Kim, Dennis H

    2017-01-24

    Animal behavior is directed by the integration of sensory information from internal states and the environment. Neuroendocrine regulation of diverse behaviors of Caenorhabditis elegans is under the control of the DAF-7/TGF-β ligand that is secreted from sensory neurons. Here, we show that C. elegans males exhibit an altered, male-specific expression pattern of daf-7 in the ASJ sensory neuron pair with the onset of reproductive maturity, which functions to promote male-specific mate-searching behavior. Molecular genetic analysis of the switch-like regulation of daf-7 expression in the ASJ neuron pair reveals a hierarchy of regulation among multiple inputs-sex, age, nutritional status, and microbial environment-which function in the modulation of behavior. Our results suggest that regulation of gene expression in sensory neurons can function in the integration of a wide array of sensory information and facilitate decision-making behaviors in C. elegans.

  18. FGF and Notch signaling in sensory neuron formation: a multifactorial approach to understanding signaling pathway hierarchy.

    PubMed

    Voelkel, Jacob E; Harvey, Jamison A; Adams, Jason S; Lassiter, Rhonda N; Stark, Michael R

    2014-11-01

    The ophthalmic trigeminal (opV) placode exclusively gives rise to sensory neurons, making it a good model to study the molecular regulation of sensory neurogenesis. A number of signaling pathways including Wnt, PDGF, FGF, and Notch have been shown to be involved in the process of opV placode cell development. However, the regulatory relationships between these signaling pathways in placode cells are still unknown and have been difficult to study experimentally. Using a novel multifactorial approach in chick embryos that allows for inhibition of FGF throughout the tissue or in individual cells, with simultaneous inactivation of Notch signaling, we investigated the potential interaction between the FGF and Notch signaling pathways in trigeminal sensory neurogenesis. This study builds on prior research describing the individual role of FGF signaling or Notch signaling in opV placode development, where blocking FGF signaling resulted in neurogenesis failure, while blocking Notch signaling resulted in enhanced neurogenesis. Reported here, blocking both pathways simultaneously resulted in a reduction in the number of cells delaminating from the opV placode and undergoing sensory neuron differentiation. Further, Notch inhibition alone did not lead to an increase in the number of cells expressing FGFR4 or in the FGFR4 expression domain, but did result in a highly fragmented basal lamina, which was reversed when blocking FGF signaling. Cumulatively, the results presented here do not support a model of Notch/FGF interdependence, rather that FGF and Notch act in parallel to promote sensory neurogenesis.

  19. Phasic and Tonic Patterns of Locus Coeruleus Output Differentially Modulate Sensory Network Function in the Awake Rat

    PubMed Central

    Waterhouse, Barry D.

    2011-01-01

    Neurons of the nucleus locus coeruleus (LC) discharge with phasic bursts of activity superimposed on highly regular tonic discharge rates. Phasic bursts are elicited by bottom-up input mechanisms involving novel/salient sensory stimuli and top-down decision making processes; whereas tonic rates largely fluctuate according to arousal levels and behavioral states. Although it is generally believed that these two modes of activity differentially modulate information processing in LC targets, the unique role of phasic versus tonic LC output on signal processing in cells, circuits, and neural networks of waking animals is not well understood. In the current study, simultaneous recordings of individual neurons within ventral posterior medial thalamus and barrel field cortex of conscious rats provided evidence that each mode of LC output produces a unique modulatory impact on single neuron responsiveness to sensory-driven synaptic input and representations of sensory information across ensembles of simultaneously recorded cells. Each mode of LC activation specifically modulated the relationship between sensory-stimulus intensity and the subsequent responses of individual neurons and neural ensembles. Overall these results indicate that phasic versus tonic modes of LC discharge exert fundamentally different modulatory effects on target neuronal circuits within the rodent trigeminal somatosensory system. As such, each mode of LC output may differentially influence signal processing as a means of optimizing behaviorally relevant neural computations within this sensory network. Likely the ability of the LC system to differentially regulate neural responses and local circuit operations according to behavioral demands extends to other brain regions including those involved in higher cognitive functions. PMID:20980542

  20. Sensory Neurons that Detect Stretch and Nutrients in the Digestive System.

    PubMed

    Williams, Erika K; Chang, Rui B; Strochlic, David E; Umans, Benjamin D; Lowell, Bradford B; Liberles, Stephen D

    2016-06-30

    Neural inputs from internal organs are essential for normal autonomic function. The vagus nerve is a key body-brain connection that monitors the digestive, cardiovascular, and respiratory systems. Within the gastrointestinal tract, vagal sensory neurons detect gut hormones and organ distension. Here, we investigate the molecular diversity of vagal sensory neurons and their roles in sensing gastrointestinal inputs. Genetic approaches allowed targeted investigation of gut-to-brain afferents involved in homeostatic responses to ingested nutrients (GPR65 neurons) and mechanical distension of the stomach and intestine (GLP1R neurons). Optogenetics, in vivo ganglion imaging, and genetically guided anatomical mapping provide direct links between neuron identity, peripheral anatomy, central anatomy, conduction velocity, response properties in vitro and in vivo, and physiological function. These studies clarify the roles of vagal afferents in mediating particular gut hormone responses. Moreover, genetic control over gut-to-brain neurons provides a molecular framework for understanding neural control of gastrointestinal physiology. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. The RhoGEF Trio Functions in Sculpting Class Specific Dendrite Morphogenesis in Drosophila Sensory Neurons

    PubMed Central

    Iyer, Srividya Chandramouli; Wang, Dennis; Iyer, Eswar Prasad R.; Trunnell, Sarah A.; Meduri, Ramakrishna; Shinwari, Riaz; Sulkowski, Mikolaj J.; Cox, Daniel N.

    2012-01-01

    Background As the primary sites of synaptic or sensory input in the nervous system, dendrites play an essential role in processing neuronal and sensory information. Moreover, the specification of class specific dendrite arborization is critically important in establishing neural connectivity and the formation of functional networks. Cytoskeletal modulation provides a key mechanism for establishing, as well as reorganizing, dendritic morphology among distinct neuronal subtypes. While previous studies have established differential roles for the small GTPases Rac and Rho in mediating dendrite morphogenesis, little is known regarding the direct regulators of these genes in mediating distinct dendritic architectures. Methodology/Principal Findings Here we demonstrate that the RhoGEF Trio is required for the specification of class specific dendritic morphology in dendritic arborization (da) sensory neurons of the Drosophila peripheral nervous system (PNS). Trio is expressed in all da neuron subclasses and loss-of-function analyses indicate that Trio functions cell-autonomously in promoting dendritic branching, field coverage, and refining dendritic outgrowth in various da neuron subtypes. Moreover, overexpression studies demonstrate that Trio acts to promote higher order dendritic branching, including the formation of dendritic filopodia, through Trio GEF1-dependent interactions with Rac1, whereas Trio GEF-2-dependent interactions with Rho1 serve to restrict dendritic extension and higher order branching in da neurons. Finally, we show that de novo dendritic branching, induced by the homeodomain transcription factor Cut, requires Trio activity suggesting these molecules may act in a pathway to mediate dendrite morphogenesis. Conclusions/Significance Collectively, our analyses implicate Trio as an important regulator of class specific da neuron dendrite morphogenesis via interactions with Rac1 and Rho1 and indicate that Trio is required as downstream effector in Cut

  2. Evidence for regulatory diversity and auto-regulation at the TAC1 locus in sensory neurones.

    PubMed

    Shanley, Lynne; Lear, Marissa; Davidson, Scott; Ross, Ruth; MacKenzie, Alasdair

    2011-02-04

    The neuropeptide substance-P (SP) is expressed from the TAC1 gene in sensory neurones where it acts as a key modulator of neurogenic inflammation. The promoter of TAC1 (TAC1prom) plays a central role in the regulation of the TAC1 gene but requires the presence of a second regulatory element; ECR2, to support TAC1 expression in sensory neurones and to respond appropriately to signalling pathways such as MAPkinases and noxious induction by capsaicin. We examined whether the effect of capsaicin on ECR2-TAC1prom activity in larger diameter neurones was cell autonomous or non- cell autonomous. We demonstrate that TRPV1 is not expressed in all the same cells as SP following capsaicin induction suggesting the presence of a non-cell autonomous mechanism for TAC1 up-regulation following capsaicin induction. In addition, we demonstrate that induction of SP and ECR1-TAC1prom activity in these larger diameter neurones can be induced by potassium depolarisation suggesting that, in addition to capsaicin induction, transgene activity may be modulated by voltage gated calcium channels. Furthermore, we show that NK1 is expressed in all SP- expressing cells after capsaicin induction and that an agonist of NK1 can activate both SP and the transgene in larger diameter neurones. These observations suggest the presence of an autocrine loop that controls the expression of the TAC1 promoter in sensory neurones. In contrast, induction of the TAC1 promoter by LPS was not dependent on ECR2 and did not occur in large diameter neurones. These studies demonstrate the diversity of mechanisms modulating the activity of the TAC1 promoter and provide novel directions for the development of new anti-inflammatory therapies.

  3. The Relationship of Neuronal Activity within the Sensori-Motor Region of the Subthalamic Nucleus to Speech

    ERIC Educational Resources Information Center

    Watson, Peter; Montgomery, Erwin B., Jr.

    2006-01-01

    Microelectrode recordings of human sensori-motor subthalamic neuronal activity during spoken sentence and syllable-repetition tasks provided an opportunity to evaluate the relationship between changes in neuronal activities and specific aspects of these vocal behaviors. Observed patterns of neuronal activity included a build up of activity in…

  4. Knockout of glial channel ACD-1 exacerbates sensory deficits in a C. elegans mutant by regulating calcium levels of sensory neurons

    PubMed Central

    Wang, Ying; D'Urso, Giulia

    2012-01-01

    Degenerin/epithelial Na+ channels (DEG/ENaCs) are voltage-independent Na+ or Na+/Ca2+ channels expressed in many tissues and are needed for a wide range of physiological functions, including sensory perception and transepithelial Na+ transport. In the nervous system, DEG/ENaCs are expressed in both neurons and glia. However, the role of glial vs. neuronal DEG/ENaCs remains unclear. We recently reported the characterization of a novel DEG/ENaC in Caenorhabditis elegans that we named ACD-1. ACD-1 is expressed in glial amphid sheath cells. The glial ACD-1, together with the neuronal DEG/ENaC DEG-1, is necessary for acid avoidance and attraction to lysine. We report presently that knockout of acd-1 in glia exacerbates sensory deficits caused by another mutant: the hypomorphic allele of the cGMP-gated channel subunit tax-2. Furthermore, sensory deficits caused by mutations in Gi protein odr-3 and guanylate cyclase daf-11, which regulate the activity of TAX-2/TAX-4 channels, are worsened by knockout of acd-1. We also show that sensory neurons of acd-1 tax-2(p694) double mutants fail to undergo changes in intracellular Ca2+ when animals are exposed to low concentrations of attractant. Finally, we show that exogenous expression of TRPV1 in sensory neurons and exposure to capsaicin rescue sensory deficits of acd-1 tax-2(p694) mutants, suggesting that sensory deficits of these mutants are bypassed by increasing neuronal excitability. Our data suggest a role of glial DEG/ENaC channel ACD-1 in supporting neuronal activity. PMID:21994266

  5. Knockout of glial channel ACD-1 exacerbates sensory deficits in a C. elegans mutant by regulating calcium levels of sensory neurons.

    PubMed

    Wang, Ying; D'Urso, Giulia; Bianchi, Laura

    2012-01-01

    Degenerin/epithelial Na(+) channels (DEG/ENaCs) are voltage-independent Na(+) or Na(+)/Ca(2+) channels expressed in many tissues and are needed for a wide range of physiological functions, including sensory perception and transepithelial Na(+) transport. In the nervous system, DEG/ENaCs are expressed in both neurons and glia. However, the role of glial vs. neuronal DEG/ENaCs remains unclear. We recently reported the characterization of a novel DEG/ENaC in Caenorhabditis elegans that we named ACD-1. ACD-1 is expressed in glial amphid sheath cells. The glial ACD-1, together with the neuronal DEG/ENaC DEG-1, is necessary for acid avoidance and attraction to lysine. We report presently that knockout of acd-1 in glia exacerbates sensory deficits caused by another mutant: the hypomorphic allele of the cGMP-gated channel subunit tax-2. Furthermore, sensory deficits caused by mutations in G(i) protein odr-3 and guanylate cyclase daf-11, which regulate the activity of TAX-2/TAX-4 channels, are worsened by knockout of acd-1. We also show that sensory neurons of acd-1 tax-2(p694) double mutants fail to undergo changes in intracellular Ca(2+) when animals are exposed to low concentrations of attractant. Finally, we show that exogenous expression of TRPV1 in sensory neurons and exposure to capsaicin rescue sensory deficits of acd-1 tax-2(p694) mutants, suggesting that sensory deficits of these mutants are bypassed by increasing neuronal excitability. Our data suggest a role of glial DEG/ENaC channel ACD-1 in supporting neuronal activity.

  6. Lamin B1 is required for mature neuron-specific gene expression during olfactory sensory neuron differentiation

    PubMed Central

    Gigante, Crystal M.; Dibattista, Michele; Dong, Frederick N.; Zheng, Xiaobin; Yue, Sibiao; Young, Stephen G.; Reisert, Johannes; Zheng, Yixian; Zhao, Haiqing

    2017-01-01

    B-type lamins are major constituents of the nuclear lamina in all metazoan cells, yet have specific roles in the development of certain cell types. Although they are speculated to regulate gene expression in developmental contexts, a direct link between B-type lamins and developmental gene expression in an in vivo system is currently lacking. Here, we identify lamin B1 as a key regulator of gene expression required for the formation of functional olfactory sensory neurons. By using targeted knockout in olfactory epithelial stem cells in adult mice, we show that lamin B1 deficient neurons exhibit attenuated response to odour stimulation. This deficit can be explained by decreased expression of genes involved in mature neuron function, along with increased expression of genes atypical of the olfactory lineage. These results support that the broadly expressed lamin B1 regulates expression of a subset of genes involved in the differentiation of a specific cell type. PMID:28425486

  7. Strongly alkaline pH avoidance mediated by ASH sensory neurons in C. elegans.

    PubMed

    Sassa, Toshihiro; Murayama, Takashi; Maruyama, Ichi N

    2013-10-25

    High pH is a noxious stimulus to animals, and their ability to avoid dangerously alkaline pH is critical for survival. However, the means by which they sense high pH has not been determined. The nematode Caenorhabditis elegans (C. elegans) avoids environmental pH above 10.5. In contrast, C. elegans mutants with structurally, developmentally, and/or functionally abnormal sensory cilia fail to avoid high pH, suggesting that sensory neurons in the cilia participate in sensing. Genetic rescue of the mutants indicates that ASH polymodal sensory neurons play a vital role in the process. Consistently, specific laser ablation of ASH neurons made animals insensitive to high pH. Furthermore, avoidance assays of other mutants also indicated that transient receptor potential vanilloid type (TRPV) ion channels encoded by osm-9 and ocr-2 are involved in sensing. Indeed, genetic rescue of osm-9 mutants by specifically expressing OSM-9 in ASH showed that TRPV channels play an essential role in sensing of high pH. Ca(2+) imaging in vivo also revealed that ASH neurons were activated by high pH stimulation, but ASH of osm-9 or ocr-2 mutants were not. These results demonstrate that in C. elegans, high pH is sensed by ASH nociceptors through opening of OSM-9/OCR-2 TRPV channels. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  8. The vanilloid receptor TRPV1 is activated and sensitized by local anesthetics in rodent sensory neurons.

    PubMed

    Leffler, Andreas; Fischer, Michael J; Rehner, Dietlinde; Kienel, Stephanie; Kistner, Katrin; Sauer, Susanne K; Gavva, Narender R; Reeh, Peter W; Nau, Carla

    2008-02-01

    Local anesthetics (LAs) block the generation and propagation of action potentials by interacting with specific sites of voltage-gated Na(+) channels. LAs can also excite sensory neurons and be neurotoxic through mechanisms that are as yet undefined. Nonspecific cation channels of the transient receptor potential (TRP) channel family that are predominantly expressed by nociceptive sensory neurons render these neurons sensitive to a variety of insults. Here we demonstrated that the LA lidocaine activated TRP channel family receptors TRPV1 and, to a lesser extent, TRPA1 in rodent dorsal root ganglion sensory neurons as well as in HEK293t cells expressing TRPV1 or TRPA1. Lidocaine also induced a TRPV1-dependent release of calcitonin gene-related peptide (CGRP) from isolated skin and peripheral nerve. Lidocaine sensitivity of TRPV1 required segments of the putative vanilloid-binding domain within and adjacent to transmembrane domain 3, was diminished under phosphatidylinositol 4,5-bisphosphate depletion, and was abrogated by a point mutation at residue R701 in the proximal C-terminal TRP domain. These data identify TRPV1 and TRPA1 as putative key elements of LA-induced nociceptor excitation. This effect is sufficient to release CGRP, a key component of neurogenic inflammation, and warrants investigation into the role of TRPV1 and TRPA1 in LA-induced neurotoxicity.

  9. Direct action and modulating effect of (+)- and (-)-nicotine on ion channels expressed in trigeminal sensory neurons.

    PubMed

    Schreiner, Benjamin S P; Lehmann, Ramona; Thiel, Ulrike; Ziemba, Paul M; Beltrán, Leopoldo R; Sherkheli, Muhammad A; Jeanbourquin, Philippe; Hugi, Alain; Werner, Markus; Gisselmann, Günter; Hatt, Hanns

    2014-04-05

    Nicotine sensory perception is generally thought to be mediated by nicotinic acetylcholine (nACh) receptors. However, recent data strongly support the idea that other receptors (e.g., transient receptor potential A1 channel, TRPA1) and other pathways contribute to the detection mechanisms underlying the olfactory and trigeminal cell response to nicotine flavor. This is in accordance with the reported ability of humans to discriminate between (+)- and (-)- nicotine enantiomers. To get a more detailed understanding of the molecular and cellular basis underlying the sensory perception of nicotine, we studied the activity of (+)- and (-)-nicotine on cultured murine trigeminal sensory neurons and on a range of heterologously expressed receptors. The human TRPA1 channel is activated by (-)-nicotine. In this work, we show that (+)-nicotine is also an activator of this channel. Pharmacological experiments using nicotinic acetylcholine receptors and transient receptor potential blockers revealed that trigeminal neurons express one or more unidentified receptors that are sensitive to (+)- and/or (-)-nicotine. Results also indicate that the presence of extracellular calcium ions is required to elicit trigeminal neuron responses to (+)- and (-)-nicotine. Results also show that both (+)-nicotine and (-)-nicotine can block 5-hydroxytryptamine type 3 (5-HT3) receptor-mediated responses in recombinant expression systems and in cultured trigeminal neurons expressing 5-HT3 receptors. Our investigations broaden the spectra of receptors that are targets for nicotine enantiomers and give new insights into the physiological role of nicotine.

  10. Transient receptor potential ion channels in primary sensory neurons as targets for novel analgesics.

    PubMed

    Sousa-Valente, J; Andreou, A P; Urban, L; Nagy, I

    2014-05-01

    The last decade has witnessed an explosion in novel findings relating to the molecules involved in mediating the sensation of pain in humans. Transient receptor potential (TRP) ion channels emerged as the greatest group of molecules involved in the transduction of various physical stimuli into neuronal signals in primary sensory neurons, as well as, in the development of pain. Here, we review the role of TRP ion channels in primary sensory neurons in the development of pain associated with peripheral pathologies and possible strategies to translate preclinical data into the development of effective new analgesics. Based on available evidence, we argue that nociception-related TRP channels on primary sensory neurons provide highly valuable targets for the development of novel analgesics and that, in order to reduce possible undesirable side effects, novel analgesics should prevent the translocation from the cytoplasm to the cell membrane and the sensitization of the channels rather than blocking the channel pore or binding sites for exogenous or endogenous activators.

  11. Dynamic synchronization of ongoing neuronal activity across spinal segments regulates sensory information flow

    PubMed Central

    Contreras-Hernández, E; Chávez, D; Rudomin, P

    2015-01-01

    Previous studies on the correlation between spontaneous cord dorsum potentials recorded in the lumbar spinal segments of anaesthetized cats suggested the operation of a population of dorsal horn neurones that modulates, in a differential manner, transmission along pathways mediating Ib non-reciprocal postsynaptic inhibition and pathways mediating primary afferent depolarization and presynaptic inhibition. In order to gain further insight into the possible neuronal mechanisms that underlie this process, we have measured changes in the correlation between the spontaneous activity of individual dorsal horn neurones and the cord dorsum potentials associated with intermittent activation of these inhibitory pathways. We found that high levels of neuronal synchronization within the dorsal horn are associated with states of incremented activity along the pathways mediating presynaptic inhibition relative to pathways mediating Ib postsynaptic inhibition. It is suggested that ongoing changes in the patterns of functional connectivity within a distributed ensemble of dorsal horn neurones play a relevant role in the state-dependent modulation of impulse transmission along inhibitory pathways, among them those involved in the central control of sensory information. This feature would allow the same neuronal network to be involved in different functional tasks. Key points We have examined, in the spinal cord of the anaesthetized cat, the relationship between ongoing correlated fluctuations of dorsal horn neuronal activity and state-dependent activation of inhibitory reflex pathways. We found that high levels of synchronization between the spontaneous activity of dorsal horn neurones occur in association with the preferential activation of spinal pathways leading to primary afferent depolarization and presynaptic inhibition relative to activation of pathways mediating Ib postsynaptic inhibition. It is suggested that changes in synchronization of ongoing activity within a

  12. Subthreshold Membrane Conductances Enhance Directional Selectivity in Vertebrate Sensory Neurons

    PubMed Central

    Chacron, Maurice J.; Fortune, Eric S.

    2016-01-01

    Directional selectivity, in which neurons respond preferentially to one “preferred” direction of movement over the opposite “null” direction, is a critical computation that is found in the central nervous systems of many animals. Such responses are generated using two mechanisms: spatiotemporal convergence via pathways that differ in the timing of information from different locations on the receptor array and the nonlinear integration of this information. Previous studies have showed that various mechanisms may act as nonlinear integrators by suppressing the response in the null direction. Here we show, through a combination of mathematical modeling and in vivo intracellular recordings, that subthreshold membrane conductances can act as a nonlinear integrator by increasing the response in the preferred direction of motion only, thereby enhancing the directional bias. Such subthreshold conductances are ubiquitous in the CNS and therefore may be used in a wide array of computations that involve the enhancement of an existing bias arising from differential spatiotemporal filtering. PMID:20445028

  13. The functional expression of mu opioid receptors on sensory neurons is developmentally regulated; morphine analgesia is less selective in the neonate.

    PubMed

    Nandi, Reema; Beacham, Daniel; Middleton, Jacqueta; Koltzenburg, Martin; Howard, Richard F; Fitzgerald, Maria

    2004-09-01

    Opioid requirements in neonatal patients are reported to be lower than older infants and this may be a reflection of the developmental regulation of opioid receptors. In this study we have investigated the postnatal regulation of Mu opioid receptor (MOR) function in both rat lumbar dorsal root ganglion (DRG) cultures and behavioural mechanical and thermal reflex tests in rat pups. Immunostaining with MOR and selective neurofilament (NF200) antibodies was combined with calcium imaging of MOR function in cultured neonatal and adult rat dorsal root ganglion cells. Calcium imaging showed that a significantly greater number of neonatal DRG neurons expressed functional MOR compared to adult (56.5+/-3.4 versus 39.9+/-1.5%, n=8, mean+/-SEM, P<0.001). This expression is confined to the large, neurofilament positive sensory neurons, while expression in small, nociceptive, neurofilament negative neurons remains unchanged. Sensory threshold testing in rat pups showed that the analgesic potency of systemic morphine to mechanical stimulation is significantly greater in the neonate and declines with postnatal age. Morphine analgesic potency in thermal nociceptive tests did not change with postnatal age. These experiments show that the MOR expressed on large DRG neurons in neonates are functional and are subject to postnatal developmental regulation. This changing functional receptor profile is consistent with greater morphine potency in mechanical, but not thermal, sensory tests in young animals. These results have important clinical implications for the use of morphine in neonates and provide a possible explanation for the differences in morphine requirements observed in the youngest patients.

  14. Sound sensitivity of neurons in rat hippocampus during performance of a sound-guided task

    PubMed Central

    Vinnik, Ekaterina; Honey, Christian; Schnupp, Jan; Diamond, Mathew E.

    2012-01-01

    To investigate how hippocampal neurons encode sound stimuli, and the conjunction of sound stimuli with the animal's position in space, we recorded from neurons in the CA1 region of hippocampus in rats while they performed a sound discrimination task. Four different sounds were used, two associated with water reward on the right side of the animal and the other two with water reward on the left side. This allowed us to separate neuronal activity related to sound identity from activity related to response direction. To test the effect of spatial context on sound coding, we trained rats to carry out the task on two identical testing platforms at different locations in the same room. Twenty-one percent of the recorded neurons exhibited sensitivity to sound identity, as quantified by the difference in firing rate for the two sounds associated with the same response direction. Sensitivity to sound identity was often observed on only one of the two testing platforms, indicating an effect of spatial context on sensory responses. Forty-three percent of the neurons were sensitive to response direction, and the probability that any one neuron was sensitive to response direction was statistically independent from its sensitivity to sound identity. There was no significant coding for sound identity when the rats heard the same sounds outside the behavioral task. These results suggest that CA1 neurons encode sound stimuli, but only when those sounds are associated with actions. PMID:22219030

  15. Sound sensitivity of neurons in rat hippocampus during performance of a sound-guided task.

    PubMed

    Itskov, Pavel M; Vinnik, Ekaterina; Honey, Christian; Schnupp, Jan; Diamond, Mathew E

    2012-04-01

    To investigate how hippocampal neurons encode sound stimuli, and the conjunction of sound stimuli with the animal's position in space, we recorded from neurons in the CA1 region of hippocampus in rats while they performed a sound discrimination task. Four different sounds were used, two associated with water reward on the right side of the animal and the other two with water reward on the left side. This allowed us to separate neuronal activity related to sound identity from activity related to response direction. To test the effect of spatial context on sound coding, we trained rats to carry out the task on two identical testing platforms at different locations in the same room. Twenty-one percent of the recorded neurons exhibited sensitivity to sound identity, as quantified by the difference in firing rate for the two sounds associated with the same response direction. Sensitivity to sound identity was often observed on only one of the two testing platforms, indicating an effect of spatial context on sensory responses. Forty-three percent of the neurons were sensitive to response direction, and the probability that any one neuron was sensitive to response direction was statistically independent from its sensitivity to sound identity. There was no significant coding for sound identity when the rats heard the same sounds outside the behavioral task. These results suggest that CA1 neurons encode sound stimuli, but only when those sounds are associated with actions.

  16. Protons activate a cation conductance in a sub-population of rat dorsal root ganglion neurones.

    PubMed Central

    Bevan, S; Yeats, J

    1991-01-01

    1. The responses of adult and neonatal rat dorsal root ganglion (DRG) neurones to buffered acidic solutions were studied with both voltage clamp and radioactive ion flux techniques. Electrophysiological experiments were made on acutely isolated neurones and ion flux experiments were made on cells that had been in culture for 3-6 days. 2. Acid solutions of pH < 6.2 evoked a sustained, slowly inactivating inward current in neurones voltage clamped at negative holding potentials. The size of the current increased with increasing proton concentrations. This response was restricted to a sub-population (approximately 45%) of adult and neonatal rat DRG neurones and was distinct from a rapidly activating and inactivating proton-induced inward sodium current that was also found in DRG neurones. 3. The proton-activated sustained current was due to an increase in cation conductance that allowed K+, Cs+ and Na+ to pass with PK/PNa = 1.32 and PCs/PNa = 1.12. 4. Radioactive ion efflux experiments made on neonatal rat cultured DRG neurones showed that protons also increased the permeability to both [14C]guanidinium and 86Rb+ ions. The half-maximal increase in efflux rate for 86Rb+ occurred at pH 5.8. Acid solution also stimulated the efflux of 86Rb+ in cultures of adult rat neurones. 5. Cells that showed a late, sustained proton-activated current also responded to capsaicin. In addition, no proton-activated fluxes of either [14C]guanidinium or 86Rb+ ions were observed in cultures of DRG neurones that had been treated with high concentrations of capsaicin (10 microM) to kill the capsaicin-sensitive neurones. Thus this proton-activated current is restricted largely, if not exclusively, to capsaicin-sensitive peripheral sensory neurones. PMID:1726795

  17. A Thalamo-Hypothalamic Pathway That Activates Oxytocin Neurons in Social Contexts in Female Rats.

    PubMed

    Cservenák, Melinda; Keller, Dávid; Kis, Viktor; Fazekas, Emese A; Öllös, Hanna; Lékó, András H; Szabó, Éva R; Renner, Éva; Usdin, Ted B; Palkovits, Miklós; Dobolyi, Árpád

    2017-02-01

    Oxytocin is released from neurons in the paraventricular hypothalamic nucleus (PVN) in mothers upon suckling and during adult social interactions. However, neuronal pathways that activate oxytocin neurons in social contexts are not yet established. Neurons in the posterior intralaminar complex of the thalamus (PIL), which contain tuberoinfundibular peptide 39 (TIP39) and are activated by pup exposure in lactating mothers, provide a candidate projection. Innervation of oxytocin neurons by TIP39 neurons was examined by double labeling in combination with electron microscopy and retrograde tract-tracing. Potential classic neurotransmitters in TIP39 neurons were investigated by in situ hybridization histochemistry. Neurons activated after encounter with a familiar conspecific female in a familiar environment were mapped with the c-Fos technique. PVN and the supraoptic nucleus oxytocin neurons were closely apposed by an average of 2.0 and 0.4 TIP39 terminals, respectively. Asymmetric (presumed excitatory) synapses were found between TIP39 terminals and cell bodies of oxytocin neurons. In lactating rats, PIL TIP39 neurons were retrogradely labeled from the PVN. TIP39 neurons expressed vesicular glutamate transporter 2 but not glutamic acid decarboxylase 67. PIL contained a markedly increased number of c-Fos-positive neurons in response to social encounter with a familiar conspecific female. Furthermore, the PIL received ascending input from the spinal cord and the inferior colliculus. Thus, TIP39 neurons in the PIL may receive sensory input in response to social interactions and project to the PVN to innervate and excite oxytocin neurons, suggesting that the PIL-PVN projection contributes to the activation of oxytocin neurons in social contexts. Copyright © 2017 by the Endocrine Society.

  18. Tissue engineering the monosynaptic circuit of the stretch reflex arc with co-culture of embryonic motoneurons and proprioceptive sensory neurons

    PubMed Central

    Guo, Xiufang; Ayala, Jennifer E.; Gonzalez, Mercedes; Stancescu, Maria; Lambert, Stephen; Hickman, James J.

    2013-01-01

    The sensory circuit of the stretch reflex arc is composed of intrafusal muscle fibers and their innervating proprioceptive neurons that convert mechanical information regarding muscle length and tension into action potentials that synapse onto the homonymous motoneurons in the ventral spinal cord which innervate the extrafusal fibers of the same muscle. To date, the in vitro synaptic connection between proprioceptive sensory neurons and spinal motoneurons has not been demonstrated. A functional in vitro system demonstrating this connection would enable the understanding of feedback by the integration of sensory input into the spinal reflex arc. Here we report a co-culture of rat embryonic motoneurons and proprioceptive sensory neurons from dorsal root ganglia (DRG) in a defined serum-free medium on a synthetic silane substrate (DETA). Furthermore, we have demonstrated functional synapse formation in the co-culture by immunocytochemistry and electrophysiological analysis. This work will be valuable for enabling in vitro model systems for the study of spinal motor control and related pathologies such as spinal cord injury, muscular dystrophy and spasticity by improving our understanding of the integration of the mechanosensitive feedback mechanism. PMID:22594977

  19. Genetic ablation of GINIP-expressing primary sensory neurons strongly impairs Formalin-evoked pain

    PubMed Central

    Urien, Louise; Gaillard, Stéphane; Lo Re, Laure; Malapert, Pascale; Bohic, Manon; Reynders, Ana; Moqrich, Aziz

    2017-01-01

    Primary sensory neurons are heterogeneous by myriad of molecular criteria. However, the functional significance of this remarkable heterogeneity is just emerging. We precedently described the GINIP+ neurons as a new subpopulation of non peptidergic C-fibers encompassing the free nerve ending cutaneous MRGPRD+ neurons and C-LTMRs. Using our recently generated ginip mouse model, we have been able to selectively ablate the GINIP+ neurons and assess their functional role in the somatosensation. We found that ablation of GINIP+ neurons affected neither the molecular contents nor the central projections of the spared neurons. GINIP-DTR mice exhibited impaired sensation to gentle mechanical stimuli applied to their hairy skin and had normal responses to noxious mechanical stimuli applied to their glabrous skin, under acute and injury-induced conditions. Importantly, loss of GINIP+ neurons significantly altered formalin-evoked first pain and drastically suppressed the second pain response. Given that MRGPRD+ neurons have been shown to be dispensable for formalin-evoked pain, our study suggest that C-LTMRs play a critical role in the modulation of formalin-evoked pain. PMID:28240741

  20. Somatosensory response properties of excitatory and inhibitory neurons in rat motor cortex

    PubMed Central

    Murray, Peter D.

    2011-01-01

    In sensory cortical networks, peripheral inputs differentially activate excitatory and inhibitory neurons. Inhibitory neurons typically have larger responses and broader receptive field tuning compared with excitatory neurons. These differences are thought to underlie the powerful feedforward inhibition that occurs in response to sensory input. In the motor cortex, as in the somatosensory cortex, cutaneous and proprioceptive somatosensory inputs, generated before and during movement, strongly and dynamically modulate the activity of motor neurons involved in a movement and ultimately shape cortical command. Human studies suggest that somatosensory inputs modulate motor cortical activity in a center excitation, surround inhibition manner such that input from the activated muscle excites motor cortical neurons that project to it, whereas somatosensory input from nearby, nonactivated muscles inhibit these neurons. A key prediction of this hypothesis is that inhibitory and excitatory motor cortical neurons respond differently to somatosensory inputs. We tested this prediction with the use of multisite extracellular recordings in anesthetized rats. We found that fast-spiking (presumably inhibitory) neurons respond to tactile and proprioceptive inputs at shorter latencies and larger response magnitudes compared with regular-spiking (presumably excitatory) neurons. In contrast, we found no differences in the receptive field size of these neuronal populations. Strikingly, all fast-spiking neuron pairs analyzed with cross-correlation analysis displayed common excitation, which was significantly more prevalent than common excitation for regular-spiking neuron pairs. These findings suggest that somatosensory inputs preferentially evoke feedforward inhibition in the motor cortex. We suggest that this provides a mechanism for dynamic selection of motor cortical modules during voluntary movements. PMID:21653707

  1. Somatosensory response properties of excitatory and inhibitory neurons in rat motor cortex.

    PubMed

    Murray, Peter D; Keller, Asaf

    2011-09-01

    In sensory cortical networks, peripheral inputs differentially activate excitatory and inhibitory neurons. Inhibitory neurons typically have larger responses and broader receptive field tuning compared with excitatory neurons. These differences are thought to underlie the powerful feedforward inhibition that occurs in response to sensory input. In the motor cortex, as in the somatosensory cortex, cutaneous and proprioceptive somatosensory inputs, generated before and during movement, strongly and dynamically modulate the activity of motor neurons involved in a movement and ultimately shape cortical command. Human studies suggest that somatosensory inputs modulate motor cortical activity in a center excitation, surround inhibition manner such that input from the activated muscle excites motor cortical neurons that project to it, whereas somatosensory input from nearby, nonactivated muscles inhibit these neurons. A key prediction of this hypothesis is that inhibitory and excitatory motor cortical neurons respond differently to somatosensory inputs. We tested this prediction with the use of multisite extracellular recordings in anesthetized rats. We found that fast-spiking (presumably inhibitory) neurons respond to tactile and proprioceptive inputs at shorter latencies and larger response magnitudes compared with regular-spiking (presumably excitatory) neurons. In contrast, we found no differences in the receptive field size of these neuronal populations. Strikingly, all fast-spiking neuron pairs analyzed with cross-correlation analysis displayed common excitation, which was significantly more prevalent than common excitation for regular-spiking neuron pairs. These findings suggest that somatosensory inputs preferentially evoke feedforward inhibition in the motor cortex. We suggest that this provides a mechanism for dynamic selection of motor cortical modules during voluntary movements.

  2. T-type calcium channels cause bursts of spikes in motor but not sensory thalamic neurons during mimicry of natural patterns of synaptic input

    PubMed Central

    Kim, Haram R.; Hong, Su Z.; Fiorillo, Christopher D.

    2015-01-01

    Although neurons within intact nervous systems can be classified as ‘sensory’ or ‘motor,’ it is not known whether there is any general distinction between sensory and motor neurons at the cellular or molecular levels. Here, we extend and test a theory according to which activation of certain subtypes of voltage-gated ion channel (VGC) generate patterns of spikes in neurons of motor systems, whereas VGC are proposed to counteract patterns in sensory neurons. We previously reported experimental evidence for the theory from visual thalamus, where we found that T-type calcium channels (TtCCs) did not cause bursts of spikes but instead served the function of ‘predictive homeostasis’ to maximize the causal and informational link between retinogeniculate excitation and spike output. Here, we have recorded neurons in brain slices from eight sensory and motor regions of rat thalamus while mimicking key features of natural excitatory and inhibitory post-synaptic potentials. As predicted by theory, TtCC did cause bursts of spikes in motor thalamus. TtCC-mediated responses in motor thalamus were activated at more hyperpolarized potentials and caused larger depolarizations with more spikes than in visual and auditory thalamus. Somatosensory thalamus is known to be more closely connected to motor regions relative to auditory and visual thalamus, and likewise the strength of its TtCC responses was intermediate between these regions and motor thalamus. We also observed lower input resistance, as well as limited evidence of stronger hyperpolarization-induced (‘H-type’) depolarization, in nuclei closer to motor output. These findings support our theory of a specific difference between sensory and motor neurons at the cellular level. PMID:26582654

  3. Rapid Integration of Artificial Sensory Feedback during Operant Conditioning of Motor Cortex Neurons.

    PubMed

    Prsa, Mario; Galiñanes, Gregorio L; Huber, Daniel

    2017-02-22

    Neuronal motor commands, whether generating real or neuroprosthetic movements, are shaped by ongoing sensory feedback from the displacement being produced. Here we asked if cortical stimulation could provide artificial feedback during operant conditioning of cortical neurons. Simultaneous two-photon imaging and real-time optogenetic stimulation were used to train mice to activate a single neuron in motor cortex (M1), while continuous feedback of its activity level was provided by proportionally stimulating somatosensory cortex. This artificial signal was necessary to rapidly learn to increase the conditioned activity, detect correct performance, and maintain the learned behavior. Population imaging in M1 revealed that learning-related activity changes are observed in the conditioned cell only, which highlights the functional potential of individual neurons in the neocortex. Our findings demonstrate the capacity of animals to use an artificially induced cortical channel in a behaviorally relevant way and reveal the remarkable speed and specificity at which this can occur.

  4. Control of P2X3 channel function by metabotropic P2Y2 utp receptors in primary sensory neurons.

    PubMed

    Mo, Gary; Peleshok, Jennifer C; Cao, Chang-Qing; Ribeiro-da-Silva, Alfredo; Séguéla, Philippe

    2013-03-01

    Purinergic signaling contributes significantly to pain mechanisms, and the nociceptor-specific P2X3 ATP receptor channel is considered a target in pain therapeutics. Recent findings suggesting the coexpression of metabotropic P2Y receptors with P2X3 implies that ATP release triggers the activation of both ionotropic and metabotropic purinoceptors, with strong potential for functional interaction. Modulation of native P2X3 function by P2Y receptor activation was investigated in rat dorsal root ganglia (DRG) neurons using whole cell patch-clamp recordings. Application of the selective P2Y receptor agonist UTP decreased peak amplitudes of α,β-meATP-evoked homomeric P2X3-mediated currents, but had no effect on heteromeric P2X2/3-mediated currents. Treatment with phospholipase C inhibitor U73122 significantly reversed P2X3 current inhibition induced by UTP-sensitive P2Y receptor activation. We previously reported the modulation of P2X receptors by phospholipids in DRG neurons and injection of exogenous phosphatidylinositol-4,5-bisphosphate (PIP(2)) fully reverses UTP-mediated regulation of P2X3 channel activity. Pharmacological as well as functional screening of P2Y receptor subtypes indicates the predominant involvement of P2Y2 receptor in P2X3 inhibition, and immunolocalization confirms a significant cellular coexpression of P2X3 and P2Y2 in rat DRG neurons. In summary, the function of P2X3 ATP receptor can be inhibited by P2Y2-mediated depletion of PIP(2). We propose that expression of P2Y2 purinoceptor in nociceptive sensory neurons provides an homeostatic mechanism to prevent excessive ATP signaling through P2X3 receptor channels.

  5. Cardiac Arrest-Induced Global Brain Hypoxia-Ischemia during Development Affects Spontaneous Activity Organization in Rat Sensory and Motor Thalamocortical Circuits during Adulthood.

    PubMed

    Shoykhet, Michael; Middleton, Jason W

    2016-01-01

    Normal maturation of sensory information processing in the cortex requires patterned synaptic activity during developmentally regulated critical periods. During early development, spontaneous synaptic activity establishes required patterns of synaptic input, and during later development it influences patterns of sensory experience-dependent neuronal firing. Thalamocortical neurons occupy a critical position in regulating the flow of patterned sensory information from the periphery to the cortex. Abnormal thalamocortical inputs may permanently affect the organization and function of cortical neuronal circuits, especially if they occur during a critical developmental window. We examined the effect of cardiac arrest (CA)-associated global brain hypoxia-ischemia in developing rats on spontaneous and evoked firing of somatosensory thalamocortical neurons and on large-scale correlations in the motor thalamocortical circuit. The mean spontaneous and sensory-evoked firing rate activity and variability were higher in CA injured rats. Furthermore, spontaneous and sensory-evoked activity and variability were correlated in uninjured rats, but not correlated in neurons from CA rats. Abnormal activity patterns of ventroposterior medial nucleus (VPm) neurons persisted into adulthood. Additionally, we found that neurons in the entopeduncular nucleus (EPN) in the basal ganglia had lower firing rates yet had higher variability and higher levels of burst firing after injury. Correlated levels of power in local field potentials (LFPs) between the EPN and the motor cortex (MCx) were also disrupted by injury. Our findings indicate that hypoxic-ischemic injury during development leads to abnormal spontaneous and sensory stimulus-evoked input patterns from thalamus to cortex. Abnormal thalamic inputs likely permanently and detrimentally affect the organization of cortical circuitry and processing of sensory information. Hypoxic-ischemic injury also leads to abnormal single neuron and

  6. Cardiac Arrest-Induced Global Brain Hypoxia-Ischemia during Development Affects Spontaneous Activity Organization in Rat Sensory and Motor Thalamocortical Circuits during Adulthood

    PubMed Central

    Shoykhet, Michael; Middleton, Jason W.

    2016-01-01

    Normal maturation of sensory information processing in the cortex requires patterned synaptic activity during developmentally regulated critical periods. During early development, spontaneous synaptic activity establishes required patterns of synaptic input, and during later development it influences patterns of sensory experience-dependent neuronal firing. Thalamocortical neurons occupy a critical position in regulating the flow of patterned sensory information from the periphery to the cortex. Abnormal thalamocortical inputs may permanently affect the organization and function of cortical neuronal circuits, especially if they occur during a critical developmental window. We examined the effect of cardiac arrest (CA)-associated global brain hypoxia-ischemia in developing rats on spontaneous and evoked firing of somatosensory thalamocortical neurons and on large-scale correlations in the motor thalamocortical circuit. The mean spontaneous and sensory-evoked firing rate activity and variability were higher in CA injured rats. Furthermore, spontaneous and sensory-evoked activity and variability were correlated in uninjured rats, but not correlated in neurons from CA rats. Abnormal activity patterns of ventroposterior medial nucleus (VPm) neurons persisted into adulthood. Additionally, we found that neurons in the entopeduncular nucleus (EPN) in the basal ganglia had lower firing rates yet had higher variability and higher levels of burst firing after injury. Correlated levels of power in local field potentials (LFPs) between the EPN and the motor cortex (MCx) were also disrupted by injury. Our findings indicate that hypoxic-ischemic injury during development leads to abnormal spontaneous and sensory stimulus-evoked input patterns from thalamus to cortex. Abnormal thalamic inputs likely permanently and detrimentally affect the organization of cortical circuitry and processing of sensory information. Hypoxic-ischemic injury also leads to abnormal single neuron and

  7. The Sensory Impact of Nicotine on Noradrenergic and Dopaminergic Neurons of the Nicotine Reward - Addiction Neurocircuitry

    PubMed Central

    Rose, Jed E; Dehkordi, Ozra; Manaye, Kebreten F; Millis, Richard M; Cianaki, Salman Ameri; Jayam-Trouth, Annapurni

    2016-01-01

    The sensory experience of smoking is a key component of nicotine addiction known to result, in part, from stimulation of nicotinic acetylcholine receptors (nAChRs) at peripheral sensory nerve endings. Such stimulation of nAChRs is followed by activation of neurons at multiple sites in the mesocorticolimbic reward pathways. However, the neurochemical profiles of CNS cells that mediate the peripheral sensory impact of nicotine remain unknown. In the present study in mice, we first used c-Fos immunohistochemistry to identify CNS cells stimulated by nicotine (NIC, 40 μg/kg, IP) and by a peripherally-acting analog of nicotine, nicotine pyrrolidine methiodide (NIC-PM, 30 μg/kg, IP). Sequential double-labelling was then performed to determine whether noradrenergic and dopaminergic neurons of the nicotine reward-addiction circuitry were primary targets of NIC and NIC-PM. Double-labelling of NIC and/or NIC-PM activated c-Fos immunoreactive cells with tyrosine hydroxylase (TH) showed no apparent c-Fos expression by the dopaminergic cells of the ventral tegmental area (VTA). With the exception of sparse numbers of TH immunoreactive D11 cells, dopamine-containing neurons in other areas of the reward-addiction circuitry, namely periaqueductal gray, and dorsal raphe, were also devoid of c-Fos immunoreactivity. Noradrenergic neurons of locus coeruleus (LC), known to innervate VTA, were activated by both NIC and NIC-PM. These results demonstrate that noradrenergic neurons of LC are among the first structures that are stimulated by single acute IP injection of NIC and NIC-PM. Dopaminergic neurons of VTA and other CNS sites, did not respond to acute IP administration of NIC or NIC-PM by induction of c-Fos. PMID:27347434

  8. Increased acid responsiveness in vagal sensory neurons in a guinea pig model of eosinophilic esophagitis

    PubMed Central

    Hu, Youtian; Liu, Zhenyu; Yu, Xiaoyun; Pasricha, Pankaj J.; Undem, Bradley J.

    2014-01-01

    Eosinophilic esophagitis (EoE) is characterized with eosinophils and mast cells predominated allergic inflammation in the esophagus and present with esophageal dysfunctions such as dysphagia, food impaction, and heartburn. However, the underlying mechanism of esophageal dysfunctions is unclear. This study aims to determine whether neurons in the vagal sensory ganglia are modulated in a guinea pig model of EoE. Animals were actively sensitized by ovalbumin (OVA) and then challenged with aerosol OVA inhalation for 2 wk. This results in a mild esophagitis with increases in mast cells and eosinophils in the esophageal wall. Vagal nodose and jugular neurons were disassociated, and their responses to acid, capsaicin, and transient receptor potential vanilloid type 1 (TRPV1) antagonist AMG-9810 were studied by calcium imaging and whole cell patch-clamp recording. Compared with naïve animals, antigen challenge significantly increased acid responsiveness in both nodose and jugular neurons. Their responses to capsaicin were also increased after antigen challenge. AMG-9810, at a concentration that blocked capsaicin-evoked calcium influx, abolished the increase in acid-induced activation in both nodose and jugular neurons. Vagotomy strongly attenuated those increased responses of nodose and jugular neurons to both acid and capsaicin induced by antigen challenge. These data for the first time demonstrated that prolonged antigen challenge significantly increases acid responsiveness in vagal nodose and jugular ganglia neurons. This sensitization effect is mediated largely through TRPV1 and initiated at sensory nerve endings in the peripheral tissues. Allergen-induced enhancement of responsiveness to noxious stimulation by acid in sensory nerve may contribute to the development of esophageal dysfunctions such as heartburn in EoE. PMID:24875100

  9. The Sensory Impact of Nicotine on Noradrenergic and Dopaminergic Neurons of the Nicotine Reward - Addiction Neurocircuitry.

    PubMed

    Rose, Jed E; Dehkordi, Ozra; Manaye, Kebreten F; Millis, Richard M; Cianaki, Salman Ameri; Jayam-Trouth, Annapurni

    2016-04-01

    The sensory experience of smoking is a key component of nicotine addiction known to result, in part, from stimulation of nicotinic acetylcholine receptors (nAChRs) at peripheral sensory nerve endings. Such stimulation of nAChRs is followed by activation of neurons at multiple sites in the mesocorticolimbic reward pathways. However, the neurochemical profiles of CNS cells that mediate the peripheral sensory impact of nicotine remain unknown. In the present study in mice, we first used c-Fos immunohistochemistry to identify CNS cells stimulated by nicotine (NIC, 40 μg/kg, IP) and by a peripherally-acting analog of nicotine, nicotine pyrrolidine methiodide (NIC-PM, 30 μg/kg, IP). Sequential double-labelling was then performed to determine whether noradrenergic and dopaminergic neurons of the nicotine reward-addiction circuitry were primary targets of NIC and NIC-PM. Double-labelling of NIC and/or NIC-PM activated c-Fos immunoreactive cells with tyrosine hydroxylase (TH) showed no apparent c-Fos expression by the dopaminergic cells of the ventral tegmental area (VTA). With the exception of sparse numbers of TH immunoreactive D11 cells, dopamine-containing neurons in other areas of the reward-addiction circuitry, namely periaqueductal gray, and dorsal raphe, were also devoid of c-Fos immunoreactivity. Noradrenergic neurons of locus coeruleus (LC), known to innervate VTA, were activated by both NIC and NIC-PM. These results demonstrate that noradrenergic neurons of LC are among the first structures that are stimulated by single acute IP injection of NIC and NIC-PM. Dopaminergic neurons of VTA and other CNS sites, did not respond to acute IP administration of NIC or NIC-PM by induction of c-Fos.

  10. Extracellular pancuronium affects sodium current in chick embryo sensory neurones.

    PubMed Central

    Maestrone, E.; Magnelli, V.; Nobile, M.; Usai, C.

    1994-01-01

    1. The action of pancuronium on transmembrane sodium conductance was investigated in dorsal root ganglion neurones of chick embryos. The Na+ current was measured by use of the patch-clamp technique in whole-cell configuration. 2. Externally perfused pancuronium (50 microM to 1 mM) reversibly inhibited the current by a fast mechanism of action. Inhibition was concentration-dependent (with a half-effective dose of 170 microM) but not voltage-dependent. 3. The activation and inactivation kinetics of the Na+ current were estimated in pancuronium and in control solution by fitting experimental data with a Hodgkin-Huxley theoretical model. 4. The activation time constant tau m, at negative membrane voltages, was larger in the presence of pancuronium than in the control. In contrast, the inactivation time constant tau h was smaller during drug perfusion at membrane voltages < -10 mV. The steady-state inactivation h infinity was not affected by pancuronium. 5. These results suggest that pancuronium may reduce the sodium current by interacting with the sodium channels in both the resting and open states. PMID:8012707

  11. SHANK3 Deficiency Impairs Heat Hyperalgesia and TRPV1 Signaling in Primary Sensory Neurons.

    PubMed

    Han, Qingjian; Kim, Yong Ho; Wang, Xiaoming; Liu, Di; Zhang, Zhi-Jun; Bey, Alexandra L; Lay, Mark; Chang, Wonseok; Berta, Temugin; Zhang, Yan; Jiang, Yong-Hui; Ji, Ru-Rong

    2016-12-21

    Abnormal pain sensitivity is commonly associated with autism spectrum disorders (ASDs) and affects the life quality of ASD individuals. SHANK3 deficiency was implicated in ASD and pain dysregulation. Here, we report functional expression of SHANK3 in mouse dorsal root ganglion (DRG) sensory neurons and spinal cord presynaptic terminals. Homozygous and heterozygous Shank3 complete knockout (Δe4-22) results in impaired heat hyperalgesia in inflammatory and neuropathic pain. Specific deletion of Shank3 in Nav1.8-expressing sensory neurons also impairs heat hyperalgesia in homozygous and heterozygous mice. SHANK3 interacts with transient receptor potential subtype V1 (TRPV1) via Proline-rich region and regulates TRPV1 surface expression. Furthermore, capsaicin-induced spontaneous pain, inward currents in DRG neurons, and synaptic currents in spinal cord neurons are all reduced after Shank3 haploinsufficiency. Finally, partial knockdown of SHANK3 expression in human DRG neurons abrogates TRPV1 function. Our findings reveal a peripheral mechanism of SHANK3, which may underlie pain deficits in SHANK3-related ASDs.

  12. A new nonconvex variational approach for sensory neurons receptive field estimation

    NASA Astrophysics Data System (ADS)

    Drogoul, A.; Aubert, G.; Cessac, B.; Kornprobst, P.

    2016-10-01

    Determining the receptive field of a visual sensory neuron is crucial to characterize the region of the visual field and the stimuli this neuron is sensitive to. We propose a new method to estimate receptive fields by a nonconvex variational approach, thus relaxing the simplifying and unrealistic assumption of convexity made by standard approaches. The method consists of solving a relaxed discrete energy minimization problem using a proximal alternating algorithm. We compare our approach with the classical spike-triggered-average technique on simulated data, considering a typical retinal ganglion cell as ground truth. Results show a high improvement in terms of accuracy and convergence with respect to the duration of the experiment.

  13. Morphology and dendritic maturation of developing principal neurons in the rat basolateral amygdala.

    PubMed

    Ryan, Steven J; Ehrlich, David E; Rainnie, Donald G

    2016-03-01

    The basolateral nucleus of the amygdala (BLA) assigns emotional valence to sensory stimuli, and many amygdala-dependent behaviors undergo marked development during postnatal life. We recently showed principal neurons in the rat BLA undergo dramatic changes to their electrophysiological properties during the first postnatal month, but no study to date has thoroughly characterized changes to morphology or gene expression that may underlie the functional development of this neuronal population. We addressed this knowledge gap with reconstructions of biocytin-filled principal neurons in the rat BLA at postnatal days 7 (P7), 14, 21, 28, and 60. BLA principal neurons underwent a number of morphological changes, including a twofold increase in soma volume from P7 to P21. Dendritic arbors expanded significantly during the first postnatal month and achieved a mature distribution around P28, in terms of total dendritic length and distance from soma. The number of primary dendrites and branch points were consistent with age, but branch points were found farther from the soma in older animals. Dendrites of BLA principal neurons at P7 had few spines, and spine density increased nearly fivefold by P21. Given the concurrent increase in dendritic material, P60 neurons had approximately 17 times as many total spines as P7 neurons. Together, these developmental transitions in BLA principal neuron morphology help explain a number of concomitant electrophysiological changes during a critical period in amygdala development.

  14. Neuronal Entropy-Rate Feature of Entopeduncular Nucleus in Rat Model of Parkinson's Disease.

    PubMed

    Darbin, Olivier; Jin, Xingxing; Von Wrangel, Christof; Schwabe, Kerstin; Nambu, Atsushi; Naritoku, Dean K; Krauss, Joachim K; Alam, Mesbah

    2016-03-01

    The function of the nigro-striatal pathway on neuronal entropy in the basal ganglia (BG) output nucleus, i.e. the entopeduncular nucleus (EPN) was investigated in the unilaterally 6-hyroxydopamine (6-OHDA)-lesioned rat model of Parkinson's disease (PD). In both control subjects and subjects with 6-OHDA lesion of dopamine (DA) the nigro-striatal pathway, a histological hallmark for parkinsonism, neuronal entropy in EPN was maximal in neurons with firing rates ranging between 15 and 25 Hz. In 6-OHDA lesioned rats, neuronal entropy in the EPN was specifically higher in neurons with firing rates above 25 Hz. Our data establishes that the nigro-striatal pathway controls neuronal entropy in motor circuitry and that the parkinsonian condition is associated with abnormal relationship between firing rate and neuronal entropy in BG output nuclei. The neuronal firing rates and entropy relationship provide putative relevant electrophysiological information to investigate the sensory-motor processing in normal condition and conditions such as movement disorders.

  15. Depletion of calcium stores in injured sensory neurons: anatomic and functional correlates.

    PubMed

    Gemes, Geza; Rigaud, Marcel; Weyker, Paul D; Abram, Stephen E; Weihrauch, Dorothee; Poroli, Mark; Zoga, Vasiliki; Hogan, Quinn H

    2009-08-01

    Painful nerve injury leads to disrupted Ca signaling in primary sensory neurons, including decreased endoplasmic reticulum (ER) Ca storage. This study examines potential causes and functional consequences of Ca store limitation after injury. Neurons were dissociated from axotomized fifth lumbar (L5) and the adjacent L4 dorsal root ganglia after L5 spinal nerve ligation that produced hyperalgesia, and they were compared to neurons from control animals. Intracellular Ca levels were measured with Fura-2 microfluorometry, and ER was labeled with probes or antibodies. Ultrastructural morphology was analyzed by electron microscopy of nondissociated dorsal root ganglia, and intracellular electrophysiological recordings were obtained from intact ganglia. Live neuron staining with BODIPY FL-X thapsigargin (Invitrogen, Carlsbad, CA) revealed a 40% decrease in sarco-endoplasmic reticulum Ca-ATPase binding in axotomized L5 neurons and a 34% decrease in L4 neurons. Immunocytochemical labeling for the ER Ca-binding protein calreticulin was unaffected by injury. Total length of ER profiles in electron micrographs was reduced by 53% in small axotomized L5 neurons, but it was increased in L4 neurons. Cisternal stacks of ER and aggregation of ribosomes occurred less frequently in axotomized neurons. Ca-induced Ca release, examined by microfluorometry with dantrolene, was eliminated in axotomized neurons. Pharmacologic blockade of Ca-induced Ca release with dantrolene produced hyperexcitability in control neurons, confirming its functional importance. After axotomy, ER Ca stores are reduced by anatomic loss and possibly diminished sarco-endoplasmic reticulum Ca-ATPase. The resulting disruption of Ca-induced Ca release and protein synthesis may contribute to the generation of neuropathic pain.

  16. A Functional Role for VEGFR1 Expressed in Peripheral Sensory Neurons in Cancer Pain

    PubMed Central

    Selvaraj, Deepitha; Gangadharan, Vijayan; Michalski, Christoph W.; Kurejova, Martina; Stösser, Sebastian; Srivastava, Kshitij; Schweizerhof, Matthias; Waltenberger, Johannes; Ferrara, Napoleone; Heppenstall, Paul; Shibuya, Masabumi; Augustin, Hellmut G.; Kuner, Rohini

    2015-01-01

    Summary Cancer pain is a debilitating disorder and a primary determinant of the poor quality of life. Here, we report a non-vascular role for ligands of the Vascular Endothelial Growth Factor (VEGF) family in cancer pain. Tumor-derived VEGF-A, PLGF-2, and VEGF-B augment pain sensitivity through selective activation of VEGF receptor 1 (VEGFR1) expressed in sensory neurons in human cancer and mouse models. Sensory-neuron-specific genetic deletion/silencing or local or systemic blockade of VEGFR1 prevented tumor-induced nerve remodeling and attenuated cancer pain in diverse mouse models in vivo. These findings identify a therapeutic potential for VEGFR1-modifying drugs in cancer pain and suggest a palliative effect for VEGF/VEGFR1-targeting anti-angiogenic tumor therapies. PMID:26058077

  17. Mechanical sensitivity and electrophysiological properties of acutely dissociated dorsal root ganglion neurons of rats.

    PubMed

    Viatchenko-Karpinski, Viacheslav; Gu, Jianguo G

    2016-11-10

    Primary afferent fibers use mechanically activated (MA) currents to transduce innocuous and noxious mechanical stimuli. However, it is largely unknown about the differences in MA currents between the afferents for sensing innocuous and noxious stimuli. In the present study, we used dorsal root ganglion (DRG) neurons acutely dissociated from rats and studied their MA currents and also their intrinsic membrane properties. Recorded from small-sized DRG neurons, we found that most of these neurons were mechanically sensitive (MS) showing MA currents. The MS neurons could be classified into nociceptive-like mechanically sensitive (Noci-MS) and non-nociceptive-like mechanically sensitive (nonNoci-MS) neurons based on their action potential shapes. Noci-MS neurons responded to mechanical stimulation with three types of MA currents, rapidly adapting (RA), intermediately adapting (IA), and slowly adapting (SA) currents. In contrast, almost all nonNoci-MS neurons showed RA current type in response to mechanical stimulation. Mechanical thresholds had a broad range for both nonNoci-MS and Noci-MS neurons, and the thresholds were not significantly different between them. However, MA current densities were significantly smaller in Noci-MS than in nonNoci-MS neurons. Noci-MS and nonNoci-MS neurons also showed significant differences in their electrophysiological properties including action potential (AP) thresholds and AP firing patterns. These differences may contribute to the differential sensory encoding for innocuous and noxious mechanical stimuli. Copyright © 2016. Published by Elsevier Ireland Ltd.

  18. GRK2 in sensory neurons regulates epinephrine-induced signalling and duration of mechanical hyperalgesia.

    PubMed

    Wang, Huijing; Heijnen, Cobi J; Eijkelkamp, Niels; Garza Carbajal, Anibal; Schedlowski, Manfred; Kelley, Keith W; Dantzer, Robert; Kavelaars, Annemieke

    2011-07-01

    Epinephrine (EPI) contributes to hyperalgesia in inflammatory and stress conditions. EPI signals via adrenoceptors, which are regulated by G protein-coupled receptor kinase 2 (GRK2). We previously reported that GRK2 is decreased in nociceptors during chronic inflammation. Herein, we investigated whether GRK2 modulates EPI-induced mechanical and thermal hyperalgesia by using GRK2(+/-) mice, which express 50% of the GRK2 protein. We demonstrate for the first time that EPI-induced mechanical as well as thermal hyperalgesia is prolonged to approximately 21 days in GRK2(+/-) mice, whereas it lasts only 3 to 4 days in wild-type mice. Using cell- specific GRK2-deficient mice, we further show that a low level of GRK2 in primary sensory neurons is critical for this prolongation of EPI-induced hyperalgesia. Low GRK2 in microglia had only a small effect on EPI-induced hyperalgesia. Low GRK2 in astrocytes did not alter EPI-induced hyperalgesia. EPI-induced hyperalgesia was prolonged similarly in mice with tamoxifen-induced homozygous or heterozygous deletion of GRK2. In terms of EPI signalling pathways, the protein kinase A (PKA) inhibitor H-89 inhibited EPI-induced mechanical hyperalgesia in wild-type mice, whereas H-89 had no effect in mice with low GRK2 in sensory neurons (SNS-GRK2(+/-) mice). Conversely, intraplantar injection of the protein kinase Cε PKCε inhibitor TAT-PKC(εv1-2) inhibited hyperalgesia in sensory neuron specific (SNS)-GRK2(+/-) mice and not in wild-type mice. These results indicate that low GRK2 in primary sensory neurons switches EPI-induced signalling from a protein kinase A-dependent toward a PKCε-dependent pathway that ultimately mediates prolonged EPI-induced hyperalgesia.

  19. Pyrethroids inhibit K2P channels and activate sensory neurons: basis of insecticide-induced paraesthesias.

    PubMed

    Castellanos, Aida; Andres, Alba; Bernal, Laura; Callejo, Gerard; Comes, Nuria; Gual, Arcadi; Giblin, Jonathan P; Roza, Carolina; Gasull, Xavier

    2017-09-25

    Pyrethroid insecticides are widely used for pest control, in agriculture or in human public health commonly as a topical treatment for scabies and head lice. Exposure to pyrethroids such as permethrin or tetramethrin (TM) causes sensory alterations such as transient pain, burning, stinging sensations and paraesthesias. Despite the well-known effects of pyrethroids on sodium channels, actions on other channels that control sensory neuron excitability are less studied. Given the role of two-pore domain potassium (K2P) channels in modulating sensory neuron excitability and firing, both in physiological and pathological conditions, we examined the effect of pyrethroids on K2P channels mainly expressed in sensory neurons. Through electrophysiological and calcium imaging experiments, we show that a high percentage of TM-responding neurons were nociceptors, which were also activated by TRPA1 and/or TRPV1 agonists. This pyrethroid also activated and enhanced the excitability of peripheral saphenous nerve fibers. Pyrethroids produced a significant inhibition of native TRESK, TRAAK, TREK-1 and TREK-2 currents. Similar effects were found in transfected HEK293 cells. At the behavioral level, intradermal TM injection in the mouse paw produced nocifensive responses and caused mechanical allodynia, demonstrating that the effects seen on nociceptors in culture lead to pain-associated behaviors in vivo. In TRESK knockout mice, pain-associated behaviors elicited by TM were enhanced, providing further evidence for a role of this channel in preventing excessive neuronal activation. Our results indicate that inhibition of K2P channels facilitates sensory neuron activation and increases their excitability. These effects contribute to the generation of paraesthesias and pain after pyrethroid exposure.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and

  20. Phosphatidylinositol 3-kinase activates ERK in primary sensory neurons and mediates inflammatory heat hyperalgesia through TRPV1 sensitization.

    PubMed

    Zhuang, Zhi-Ye; Xu, Haoxing; Clapham, David E; Ji, Ru-Rong

    2004-09-22

    Although the PI3K (phosphatidylinositol 3-kinase) pathway typically regulates cell growth and survival, increasing evidence indicates the involvement of this pathway in neural plasticity. It is unknown whether the PI3K pathway can mediate pain hypersensitivity. Intradermal injection of capsaicin and NGF produce heat hyperalgesia by activating their respective TRPV1 (transient receptor potential vanilloid receptor-1) and TrkA receptors on nociceptor sensory nerve terminals. We examined the activation of PI3K in primary sensory DRG neurons by these inflammatory agents and the contribution of PI3K activation to inflammatory pain. We further investigated the correlation between the PI3K and the ERK (extracellular signal-regulated protein kinase) pathway. Capsaicin and NGF induce phosphorylation of the PI3K downstream target AKT (protein kinase B), which is blocked by the PI3K inhibitors LY294002 and wortmannin, indicative of the activation of PI3K by both agents. ERK activation by capsaicin and NGF was also blocked by PI3K inhibitors. Similarly, intradermal capsaicin in rats activated PI3K and ERK in C-fiber DRG neurons and epidermal nerve fibers. Injection of PI3K or MEK (ERK kinase) inhibitors into the hindpaw attenuated capsaicin- and NGF-evoked heat hyperalgesia but did not change basal heat sensitivity. Furthermore, PI3K, but not ERK, inhibition blocked early induction of hyperalgesia. In acutely dissociated DRG neurons, the capsaicin-induced TRPV1 current was strikingly potentiated by NGF, and this potentiation was completely blocked by PI3K inhibitors and primarily suppressed by MEK inhibitors. Therefore, PI3K induces heat hyperalgesia, possibly by regulating TRPV1 activity, in an ERK-dependent manner. The PI3K pathway also appears to play a role that is distinct from ERK by regulating the early onset of inflammatory pain.

  1. ZBTB20 regulates nociception and pain sensation by modulating TRP channel expression in nociceptive sensory neurons.

    PubMed

    Ren, An-Jing; Wang, Kai; Zhang, Huan; Liu, Anjun; Ma, Xianhua; Liang, Qing; Cao, Dongmei; Wood, John N; He, David Z; Ding, Yu-Qiang; Yuan, Wen-Jun; Xie, Zhifang; Zhang, Weiping J

    2014-11-05

    In mammals, pain sensation is initiated by the detection of noxious stimuli through specialized transduction ion channels and receptors in nociceptive sensory neurons. Transient receptor potential (TRP) channels are the key sensory transducers that confer nociceptors distinct sensory modalities. However, the regulatory mechanisms about their expression are poorly defined. Here we show that the zinc-finger protein ZBTB20 regulates TRP channels expression in nociceptors. ZBTB20 is highly expressed in nociceptive sensory neurons of dorsal root ganglia. Disruption of ZBTB20 in nociceptors led to a marked decrease in the expression levels of TRPV1, TRPA1 and TRPM8 and the response of calcium flux and whole-cell currents evoked by their respective specific agonists. Phenotypically, the mice lacking ZBTB20 specifically in nociceptors showed a defect in nociception and pain sensation in response to thermal, mechanical and inflammatory stimulation. Our findings point to ZBTB20 as a critical regulator of nociception and pain sensation by modulating TRP channels expression in nociceptors.

  2. Electrophysiological recording from neurons controlling sensory and motor functions of the esophagus.

    PubMed

    Sengupta, J N

    2001-12-03

    Much work has been done in recent years to understand the functional roles of sensory neurons that regulate reflexes and sensations. Information about the response patterns of spinal dorsal horn and brain stem neurons associated with esophageal functions has become available by using electrophysiological techniques. These techniques allow understanding of response characteristics of neurons to various types of stimuli, neurotransmitters involved in excitation or inhibition of neurons, changes in response characteristics of neurons under pathological conditions, and the shape and size of a particular neuron in the central nervous system, as well as its projection to other areas of the brain. Response properties of primary afferent fibers in the vagus and thoracic sympathetic nerves have been studied in intact animal models by using single-fiber or extracellular microelectrode recording techniques. Recently, the single-fiber recording technique has been used in vitro in isolated esophagus-vagus nerve preparations. Recordings from the brain stem nuclei and thoracic spinal dorsal horn neurons also have examined the response characteristics of second-order neurons receiving afferent input from the esophagus. In the spinal cord, dorsal horn neurons responsive to esophageal distension also receive ipsilateral somatic input (ie, viscero-somatic convergence) from the upper thoracic area. These neurons exhibit sensitization of response after repeated noxious distension of the esophagus or instillation of irritant substances in the esophagus. In the nucleus ambiguus, neurons receiving input from the distal esophagus exhibit excitation to distension of the distal esophagus but undergo inhibition to midthoracic esophageal distension or to swallow. Neurons in the nucleus tractus solitarius receiving input from the distal esophagus exhibit 2 types of responses to proximal and distal esophageal distension. One type of response is a rhythmic firing synchronized with peristaltic

  3. Mitochondrial abnormality in sensory, but not motor, axons in paclitaxel-evoked painful peripheral neuropathy in the rat.

    PubMed

    Xiao, W H; Zheng, H; Zheng, F Y; Nuydens, R; Meert, T F; Bennett, G J

    2011-12-29

    The dose-limiting side effect of the anti-neoplastic agent, paclitaxel, is a chronic distal symmetrical peripheral neuropathy that produces sensory dysfunction (hypoesthesia and neuropathic pain) but little or no distal motor dysfunction. Similar peripheral neuropathies are seen with chemotherapeutics in the vinca alkaloid, platinum-complex, and proteasome inhibitor classes. Studies in rats suggest that the cause is a mitotoxic effect on axonal mitochondria. If so, then the absence of motor dysfunction may be due to mitotoxicity that affects sensory axons but spares motor axons. To investigate this, paclitaxel exposure levels in the dorsal root, ventral root, dorsal root ganglion, peripheral nerve, and spinal cord were measured, and the ultrastructure and the respiratory function of mitochondria in dorsal roots and ventral roots were compared. Sensory and motor axons in the roots and nerve had comparably low exposure to paclitaxel and exposure in the spinal cord was negligible. However, sensory neurons in the dorsal root ganglion had a very high and remarkably persistent (up to 10 days or more after the last injection) exposure to paclitaxel. Paclitaxel evoked a significant increase in the incidence of swollen and vacuolated mitochondria in the myelinated and unmyelinated sensory axons of the dorsal root (as seen previously in the peripheral nerve) but not in the motor axons of the ventral root. Stimulated mitochondrial respiration in the dorsal root was significantly depressed in paclitaxel-treated animals examined 2-4 weeks after the last injection, whereas respiration in the ventral root was normal. We conclude that the absence of motor dysfunction in paclitaxel-evoked peripheral neuropathy may be due to the absence of a mitotoxic effect in motor neuron axons, whereas the sensory dysfunction may be due to a mitotoxic effect resulting from the primary afferent neuron's cell body being exposed to high and persistent levels of paclitaxel.

  4. Influence of norepinephrine on somatosensory neuronal responses in the rat thalamus: a combined modeling and in vivo multi-channel, multi-neuron recording study.

    PubMed

    Moxon, Karen A; Devilbiss, David M; Chapin, John K; Waterhouse, Barry D

    2007-05-25

    Norepinephrine released within primary sensory circuits from locus coeruleus afferent fibers can produce a spectrum of modulatory actions on spontaneous or sensory-evoked activity of individual neurons. Within the ventral posterior medial thalamus, membrane currents modulated by norepinephrine have been identified. However, the relationship between the cellular effects of norepinephrine and the impact of norepinephrine release on populations of neurons encoding sensory signals is still open to question. To address this lacuna in understanding the net impact of the noradrenergic system on sensory signal processing, a computational model of the rat trigeminal somatosensory thalamus was generated. The effects of independent manipulation of different cellular actions of norepinephrine on simulated afferent input to the computational model were then examined. The results of these simulations aided in the design of in vivo neural ensemble recording experiments where sensory-driven responses of thalamic neurons were measured before and during locus coeruleus activation in waking animals. Together the simulated and experimental results reveal several key insights regarding the regulation of neural network operation by norepinephrine including: 1) cell-specific modulatory actions of norepinephrine, 2) mechanisms of norepinephrine action that can improve the tuning of the network and increase the signal-to-noise ratio of cellular responses in order to enhance network representation of salient stimulus features and 3) identification of the dynamic range of thalamic neuron function through which norepinephrine operates.

  5. Influence of Norepinephrine on Somatosensory Neuronal Responses in the Rat Thalamus: A Combined Modeling and In Vivo Multi-channel, Multi-neuron Recording Study

    PubMed Central

    Moxon, Karen A.; Devilbiss, David M.; Chapin, John K.; Waterhouse, Barry D.

    2011-01-01

    Norepinephrine released within primary sensory circuits from locus coeruleus afferent fibers can produce a spectrum of modulatory actions on spontaneous or sensory-evoked activity of individual neurons. Within the ventral posterior medial thalamus, membrane currents modulated by norepinephrine have been identified. However, the relationship between the cellular effects of norepinephrine and the impact of norepinephrine release on populations of neurons encoding sensory signals is still open to question. To address this lacuna in understanding the net impact of the noradrenergic system on sensory signal processing, a computational model of the rat trigeminal somatosensory thalamus was generated. The effects of independent manipulation of different cellular actions of norepinephrine on simulated afferent input to the computational model were then examined. The results of these simulations aided in the design of in vivo neural ensemble recording experiments where sensory-driven responses of thalamic neurons were measured before and during locus coeruleus activation in waking animals. Together the simulated and experimental results reveal several key insights regarding the regulation of neural network operation by norepinephrine including: 1) cell specific modulatory actions of norepinephrine, 2) mechanisms of norepinephrine action that can improve the tuning of the network and increase the signal-to-noise ratio of cellular responses in order to enhance network representation of salient stimulus features and 3) identification of the dynamic range of thalamic neuron function through which norepinphrine operates. PMID:17368434

  6. Rootletin organizes the ciliary rootlet to achieve neuron sensory function in Drosophila

    PubMed Central

    Kao, Ling-Rong; Jana, Swadhin C.; Sivan-Loukianova, Elena; Mendonça, Susana; Cabrera, Oscar A.; Singh, Priyanka; Cabernard, Clemens; Eberl, Daniel F.; Bettencourt-Dias, Monica

    2015-01-01

    Cilia are essential for cell signaling and sensory perception. In many cell types, a cytoskeletal structure called the ciliary rootlet links the cilium to the cell body. Previous studies indicated that rootlets support the long-term stability of some cilia. Here we report that Drosophila melanogaster Rootletin (Root), the sole orthologue of the mammalian paralogs Rootletin and C-Nap1, assembles into rootlets of diverse lengths among sensory neuron subtypes. Root mutant neurons lack rootlets and have dramatically impaired sensory function, resulting in behavior defects associated with mechanosensation and chemosensation. Root is required for cohesion of basal bodies, but the cilium structure appears normal in Root mutant neurons. We show, however, that normal rootlet assembly requires centrioles. The N terminus of Root contains a conserved domain and is essential for Root function in vivo. Ectopically expressed Root resides at the base of mother centrioles in spermatocytes and localizes asymmetrically to mother centrosomes in neuroblasts, both requiring Bld10, a basal body protein with varied functions. PMID:26483560

  7. Sensory specificity and speciation: a potential neuronal pathway for host fruit odour discrimination in Rhagoletis pomonella

    PubMed Central

    Batra, Srishti; Ramaswamy, Sree Subha; Feder, Jeffrey L.

    2016-01-01

    Behavioural changes in habitat or mate choice can trigger population divergence, leading to speciation. However, little is known about the neurological bases for such changes. Rhagoletis pomonella (Diptera: Tephritidae) is a model for ecological speciation via host plant shifts. Within the past 180 years, Rhagoletis flies infesting hawthorn (Crataegus spp.) shifted to attack domesticated apple (Malus pumila). The two populations differ in their olfactory preferences for apple versus hawthorn fruit. Here, we looked for patterns of sensory organization that may have contributed to this shift by characterizing the morphology, specificity and distribution of olfactory sensory neurons (OSNs) on the antennae of Rhagoletis responding to host fruit and non-host volatiles. Of 28 OSN classes identified, two colocalized OSN pairs were found that specifically responded to the major behavioural attractant and antagonist volatiles for each fly population. A reversal in the response of these OSNs to fruit volatiles, either through a switch in receptor expression between these paired neurons or changes in neuronal projections in the brain, could therefore account for the behavioural difference between apple and hawthorn flies. The finding supports the hypothesis that relatively minor changes in olfactory sensory pathways may contribute to rapid host shifting and divergence in Rhagoletis. PMID:28003447

  8. Injured sensory neuron-derived CSF1 induces microglia proliferation and DAP12-dependent pain

    PubMed Central

    Guan, Zhonghui; Kuhn, Julia A.; Wang, Xidao; Colquitt, Bradley; Solorzano, Carlos; Vaman, Smitha; Guan, Andrew K.; Evans-Reinsch, Zoe; Braz, Joao; Devor, Marshall; Abboud-Werner, Sherry L.; Lanier, Lewis L.; Lomvardas, Stavros; Basbaum, Allan I.

    2015-01-01

    SUMMARY Although microglia are implicated in nerve injury-induced neuropathic pain, how injured sensory neurons engage microglia is unclear. Here we demonstrate that peripheral nerve injury induces de novo expression of colony-stimulating factor 1 (CSF1) in injured sensory neurons. The CSF1 is transported to the spinal cord where it targets the microglial CSF1 receptor (CSF1R). Cre-mediated sensory neuron deletion of Csf1 completely prevented nerve injury-induced mechanical hypersensitivity and reduced microglia activation and proliferation. In contrast, intrathecal injection of CSF1 induces mechanical hypersensitivity and microglial proliferation. Nerve injury also upregulated CSF1 in motoneurons, where it is required for ventral horn microglial activation and proliferation. Downstream of CSF1R, we found that the microglial membrane adapter protein DAP12 is required for both nerve injury- and intrathecal CSF1-induced upregulation of pain-related microglial genes and the ensuing pain, but not for microglia proliferation. Thus, both CSF1 and DAP12 are potential targets for the pharmacotherapy of neuropathic pain. PMID:26642091

  9. Transient receptor potential channels encode volatile chemicals sensed by rat trigeminal ganglion neurons.

    PubMed

    Lübbert, Matthias; Kyereme, Jessica; Schöbel, Nicole; Beltrán, Leopoldo; Wetzel, Christian Horst; Hatt, Hanns

    2013-01-01

    Primary sensory afferents of the dorsal root and trigeminal ganglia constantly transmit sensory information depicting the individual's physical and chemical environment to higher brain regions. Beyond the typical trigeminal stimuli (e.g. irritants), environmental stimuli comprise a plethora of volatile chemicals with olfactory components (odorants). In spite of a complete loss of their sense of smell, anosmic patients may retain the ability to roughly discriminate between different volatile compounds. While the detailed mechanisms remain elusive, sensory structures belonging to the trigeminal system seem to be responsible for this phenomenon. In order to gain a better understanding of the mechanisms underlying the activation of the trigeminal system by volatile chemicals, we investigated odorant-induced membrane potential changes in cultured rat trigeminal neurons induced by the odorants vanillin, heliotropyl acetone, helional, and geraniol. We observed the dose-dependent depolarization of trigeminal neurons upon application of these substances occurring in a stimulus-specific manner and could show that distinct neuronal populations respond to different odorants. Using specific antagonists, we found evidence that TRPA1, TRPM8, and/or TRPV1 contribute to the activation. In order to further test this hypothesis, we used recombinantly expressed rat and human variants of these channels to investigate whether they are indeed activated by the odorants tested. We additionally found that the odorants dose-dependently inhibit two-pore potassium channels TASK1 and TASK3 heterologously expressed In Xenopus laevis oocytes. We suggest that the capability of various odorants to activate different TRP channels and to inhibit potassium channels causes neuronal depolarization and activation of distinct subpopulations of trigeminal sensory neurons, forming the basis for a specific representation of volatile chemicals in the trigeminal ganglia.

  10. Transient Receptor Potential Channels Encode Volatile Chemicals Sensed by Rat Trigeminal Ganglion Neurons

    PubMed Central

    Schöbel, Nicole; Beltrán, Leopoldo; Wetzel, Christian Horst; Hatt, Hanns

    2013-01-01

    Primary sensory afferents of the dorsal root and trigeminal ganglia constantly transmit sensory information depicting the individual’s physical and chemical environment to higher brain regions. Beyond the typical trigeminal stimuli (e.g. irritants), environmental stimuli comprise a plethora of volatile chemicals with olfactory components (odorants). In spite of a complete loss of their sense of smell, anosmic patients may retain the ability to roughly discriminate between different volatile compounds. While the detailed mechanisms remain elusive, sensory structures belonging to the trigeminal system seem to be responsible for this phenomenon. In order to gain a better understanding of the mechanisms underlying the activation of the trigeminal system by volatile chemicals, we investigated odorant-induced membrane potential changes in cultured rat trigeminal neurons induced by the odorants vanillin, heliotropyl acetone, helional, and geraniol. We observed the dose-dependent depolarization of trigeminal neurons upon application of these substances occurring in a stimulus-specific manner and could show that distinct neuronal populations respond to different odorants. Using specific antagonists, we found evidence that TRPA1, TRPM8, and/or TRPV1 contribute to the activation. In order to further test this hypothesis, we used recombinantly expressed rat and human variants of these channels to investigate whether they are indeed activated by the odorants tested. We additionally found that the odorants dose-dependently inhibit two-pore potassium channels TASK1 and TASK3 heterologously expressed In Xenopus laevis oocytes. We suggest that the capability of various odorants to activate different TRP channels and to inhibit potassium channels causes neuronal depolarization and activation of distinct subpopulations of trigeminal sensory neurons, forming the basis for a specific representation of volatile chemicals in the trigeminal ganglia. PMID:24205061

  11. Development of inner ear afferent connections: forming primary neurons and connecting them to the developing sensory epithelia

    NASA Technical Reports Server (NTRS)

    Fritzsch, Bernd

    2003-01-01

    The molecular and cellular origin of the primary neurons of the inner ear, the vestibular and spiral neurons, is reviewed including how they connect to the specific sensory epithelia and what the molecular nature of their survival is. Primary neurons of the ear depend on a single basic Helix-Loop-Helix (bHLH) protein for their formation, neurogenin 1 (ngn1). An immediate downstream gene is the bHLH gene neuronal differentiation (NeuroD). Targeted null mutations of ngn1 results in absence of primary neuron formation; targeted null mutation of NeuroD results in loss of almost all spiral and many vestibular neurons. NeuroD and a later expressed gene, Brn3a, play a role in pathfinding to and within sensory epithelia. The molecular nature of this pathfinding property is unknown. Reduction of hair cells in ngn1 null mutations suggests a clonal relationship with primary neurons. This relationship may play some role in specifying the identity of hair cells and the primary neurons that connect with them. Primary neuron neurites growth to sensory epithelia is initially independent of trophic factors released from developing sensory epithelia, but becomes rapidly dependent on those factors. Null mutations of specific neurotrophic factors lose distinct primary neuron populations which undergo rapid embryonic cell death.

  12. Development of inner ear afferent connections: forming primary neurons and connecting them to the developing sensory epithelia

    NASA Technical Reports Server (NTRS)

    Fritzsch, Bernd

    2003-01-01

    The molecular and cellular origin of the primary neurons of the inner ear, the vestibular and spiral neurons, is reviewed including how they connect to the specific sensory epithelia and what the molecular nature of their survival is. Primary neurons of the ear depend on a single basic Helix-Loop-Helix (bHLH) protein for their formation, neurogenin 1 (ngn1). An immediate downstream gene is the bHLH gene neuronal differentiation (NeuroD). Targeted null mutations of ngn1 results in absence of primary neuron formation; targeted null mutation of NeuroD results in loss of almost all spiral and many vestibular neurons. NeuroD and a later expressed gene, Brn3a, play a role in pathfinding to and within sensory epithelia. The molecular nature of this pathfinding property is unknown. Reduction of hair cells in ngn1 null mutations suggests a clonal relationship with primary neurons. This relationship may play some role in specifying the identity of hair cells and the primary neurons that connect with them. Primary neuron neurites growth to sensory epithelia is initially independent of trophic factors released from developing sensory epithelia, but becomes rapidly dependent on those factors. Null mutations of specific neurotrophic factors lose distinct primary neuron populations which undergo rapid embryonic cell death.

  13. Measuring Physiological Responses of Drosophila Sensory Neurons to Lipid Pheromones Using Live Calcium Imaging.

    PubMed

    Shankar, Shruti; Calvert, Meredith E K; Yew, Joanne Y

    2016-04-29

    Unlike mammals, insects such as Drosophila have multiple taste organs. The chemosensory neurons on the legs, proboscis, wings and ovipositor of Drosophila express gustatory receptors(1,2), ion channels(3-6), and ionotropic receptors(7) that are involved in the detection of volatile and non-volatile sensory cues. These neurons directly contact tastants such as food, noxious substances and pheromones and therefore influence many complex behaviors such as feeding, egg-laying and mating. Electrode recordings and calcium imaging have been widely used in insects to quantify the neuronal responses evoked by these tastants. However, electrophysiology requires specialized equipment and obtaining measurements from a single taste sensillum can be technically challenging depending on the cell-type, size, and position. In addition, single neuron resolution in Drosophila can be difficult to achieve since taste sensilla house more than one type of chemosensory neuron. The live calcium imaging method described here allows responses of single gustatory neurons in live flies to be measured. This method is especially suitable for imaging neuronal responses to lipid pheromones and other ligand types that have low solubility in water-based solvents.

  14. Acetyl L-carnitine protects motor neurons and Rohon-Beard sensory neurons against ketamine-induced neurotoxicity in zebrafish embryos.

    PubMed

    Cuevas, Elvis; Trickler, William J; Guo, Xiaoqing; Ali, Syed F; Paule, Merle G; Kanungo, Jyotshna

    2013-01-01

    Ketamine, a non-competitive antagonist of N-methyl-D-aspartate (NMDA) type glutamate receptors is commonly used as a pediatric anesthetic. Multiple studies have shown ketamine to be neurotoxic, particularly when administered during the brain growth spurt. Previously, we have shown that ketamine is detrimental to motor neuron development in the zebrafish embryos. Here, using both wild type (WT) and transgenic (hb9:GFP) zebrafish embryos, we demonstrate that ketamine is neurotoxic to both motor and sensory neurons. Drug absorption studies showed that in the WT embryos, ketamine accumulation was approximately 0.4% of the original dose added to the exposure medium. The transgenic embryos express green fluorescent protein (GFP) localized in the motor neurons making them ideal for evaluating motor neuron development and toxicities in vivo. The hb9:GFP zebrafish embryos (28 h post fertilization) treated with 2 mM ketamine for 20 h demonstrated significant reductions in spinal motor neuron numbers, while co-treatment with acetyl L-carnitine proved to be neuroprotective. In whole mount immunohistochemical studies using WT embryos, a similar effect was observed for the primary sensory neurons. In the ketamine-treated WT embryos, the number of primary sensory Rohon-Beard (RB) neurons was significantly reduced compared to that in controls. However, acetyl L-carnitine co-treatment prevented ketamine-induced adverse effects on the RB neurons. These results suggest that acetyl L-carnitine protects both motor and sensory neurons from ketamine-induced neurotoxicity.

  15. Ablation of sensory neurons in a genetic model of pancreatic ductal adenocarcinoma slows initiation and progression of cancer.

    PubMed

    Saloman, Jami L; Albers, Kathryn M; Li, Dongjun; Hartman, Douglas J; Crawford, Howard C; Muha, Emily A; Rhim, Andrew D; Davis, Brian M

    2016-03-15

    Pancreatic ductal adenocarcinoma (PDAC) is characterized by an exuberant inflammatory desmoplastic response. The PDAC microenvironment is complex, containing both pro- and antitumorigenic elements, and remains to be fully characterized. Here, we show that sensory neurons, an under-studied cohort of the pancreas tumor stroma, play a significant role in the initiation and progression of the early stages of PDAC. Using a well-established autochthonous model of PDAC (PKC), we show that inflammation and neuronal damage in the peripheral and central nervous system (CNS) occurs as early as the pancreatic intraepithelial neoplasia (PanIN) 2 stage. Also at the PanIN2 stage, pancreas acinar-derived cells frequently invade along sensory neurons into the spinal cord and migrate caudally to the lower thoracic and upper lumbar regions. Sensory neuron ablation by neonatal capsaicin injection prevented perineural invasion (PNI), astrocyte activation, and neuronal damage, suggesting that sensory neurons convey inflammatory signals from Kras-induced pancreatic neoplasia to the CNS. Neuron ablation in PKC mice also significantly delayed PanIN formation and ultimately prolonged survival compared with vehicle-treated controls (median survival, 7.8 vs. 4.5 mo; P = 0.001). These data establish a reciprocal signaling loop between the pancreas and nervous system, including the CNS, that supports inflammation associated with oncogenic Kras-induced neoplasia. Thus, pancreatic sensory neurons comprise an important stromal cell population that supports the initiation and progression of PDAC and may represent a potential target for prevention in high-risk populations.

  16. Whisker row deprivation affects the flow of sensory information through rat barrel cortex.

    PubMed

    Jacob, Vincent; Mitani, Akinori; Toyoizumi, Taro; Fox, Kevin

    2017-01-01

    Whisker trimming causes substantial reorganization of neuronal response properties in barrel cortex. However, little is known about experience-dependent rerouting of sensory processing following sensory deprivation. To address this, we performed in vivo intracellular recordings from layers 2/3 (L2/3), layer 4 (L4), layer 5 regular-spiking (L5RS), and L5 intrinsically bursting (L5IB) neurons and measured their multiwhisker receptive field at the level of spiking activity, membrane potential, and synaptic conductance before and after sensory deprivation. We used Chernoff information to quantify the "sensory information" contained in the firing patterns of cells in response to spared and deprived whisker stimulation. In the control condition, information for flanking-row and same-row whiskers decreased in the order L4, L2/3, L5IB, L5RS. However, after whisker-row deprivation, spared flanking-row whisker information was reordered to L4, L5RS, L5IB, L2/3. Sensory information from the trimmed whiskers was reduced and delayed in L2/3 and L5IB neurons, whereas sensory information from spared whiskers was increased and advanced in L4 and L5RS neurons. Sensory information from spared whiskers was increased in L5IB neurons without a latency change. L5RS cells exhibited the largest changes in sensory information content through an atypical plasticity combining a significant decrease in spontaneous activity and an increase in a short-latency excitatory conductance.

  17. Functional modulation of IFT kinesins extends the sensory repertoire of ciliated neurons in Caenorhabditis elegans.

    PubMed

    Evans, James E; Snow, Joshua J; Gunnarson, Amy L; Ou, Guangshuo; Stahlberg, Henning; McDonald, Kent L; Scholey, Jonathan M

    2006-02-27

    The diversity of sensory cilia on Caenorhabditis elegans neurons allows the animal to detect a variety of sensory stimuli. Sensory cilia are assembled by intraflagellar transport (IFT) kinesins, which transport ciliary precursors, bound to IFT particles, along the ciliary axoneme for incorporation into ciliary structures. Using fluorescence microscopy of living animals and serial section electron microscopy of high pressure-frozen, freeze-substituted IFT motor mutants, we found that two IFT kinesins, homodimeric OSM-3 kinesin and heterotrimeric kinesin II, function in a partially redundant manner to build full-length amphid channel cilia but are completely redundant for building full-length amphid wing (AWC) cilia. This difference reflects ci