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Sample records for rat spinal dorsal

  1. Responses of spinal neurones to cutaneous and dorsal root stimuli in rats with mechanical allodynia after contusive spinal cord injury.

    PubMed

    Drew, G M; Siddall, P J; Duggan, A W

    2001-03-01

    The firing of neurones in spinal segments adjacent to a contusive T13 spinal cord injury was characterised in anaesthetised rats. Three groups of rats were examined: (1) allodynic spinally injured, (2) non-allodynic spinally injured and (3) normal, uninjured. Spinal cord field potentials evoked by electrical dorsal root stimulation and the responses of 207 dorsal horn neurones to mechanical stimuli applied to the skin were studied. Within the lesioned spinal segment few active neurones were encountered and field potentials were absent. Depolarising field potentials recorded rostral to the lesion were reduced in both allodynic and non-allodynic animals compared to uninjured controls, while those recorded in caudal segments were enhanced in allodynic animals. Neuronal recordings revealed that allodynia was associated with exaggerated responses, including afterdischarges, to innocuous and noxious mechanical stimuli in a proportion of wide dynamic range, but not low threshold, neurones. These changes were observed both rostral and caudal to the site of injury. The results suggest that an increased responsiveness of some dorsal horn neurones in segments neighbouring a contusive spinal cord injury may contribute to the expression of mechanical allodynia. It is proposed that a relative lack of inhibition underlies altered cell responses. PMID:11222993

  2. Responses of spinal dorsal horn neurons to foot movements in rats with a sprained ankle.

    PubMed

    Kim, Jae Hyo; Kim, Hee Young; Chung, Kyungsoon; Chung, Jin Mo

    2011-05-01

    Acute ankle injuries are common problems and often lead to persistent pain. To investigate the underlying mechanism of ankle sprain pain, the response properties of spinal dorsal horn neurons were examined after ankle sprain. Acute ankle sprain was induced manually by overextending the ankle of a rat hindlimb in a direction of plantarflexion and inversion. The weight-bearing ratio (WBR) of the affected foot was used as an indicator of pain. Single unit activities of dorsal horn neurons in response to plantarflexion and inversion of the foot or ankle compression were recorded from the medial part of the deep dorsal horn, laminae IV-VI, in normal and ankle-sprained rats. One day after ankle sprain, rats showed significantly reduced WBRs on the affected foot, and this reduction was partially restored by systemic morphine. The majority of deep dorsal horn neurons responded to a single ankle stimulus modality. After ankle sprain, the mean evoked response rates were significantly increased, and afterdischarges were developed in recorded dorsal horn neurons. The ankle sprain-induced enhanced evoked responses were significantly reduced by morphine, which was reversed by naltrexone. The data indicate that movement-specific dorsal horn neuron responses were enhanced after ankle sprain in a morphine-dependent manner, thus suggesting that hyperactivity of dorsal horn neurons is an underlying mechanism of pain after ankle sprain. PMID:21389306

  3. Control of glutamatergic neurotransmission in the rat spinal dorsal horn by the nucleoside transporter ENT1.

    PubMed

    Ackley, Michael A; Governo, Ricardo J M; Cass, Carol E; Young, James D; Baldwin, Stephen A; King, Anne E

    2003-04-15

    Adenosine modulates nociceptive processing in the superficial dorsal horn of the spinal cord. In other tissues, membrane transporters influence profoundly the extracellular levels of adenosine. To investigate the putative role of nucleoside transporters in the regulation of excitatory synaptic transmission in the dorsal horn, we employed immunohistochemistry and whole-cell patch-clamp recording of substantia gelatinosa neurons in slices of rat spinal cord in vitro. The rat equilibrative nucleoside transporter (rENT1) was revealed by antibody staining to be abundant in neonatal and mature dorsal horn, especially within laminae I-III. This was confirmed by immunoblots of dorsal horn homogenate. Nitrobenzylthioinosine (NBMPR), a potent non-transportable inhibitor of rENT1, attenuated synaptically evoked EPSCs onto lamina II neurons in a concentration-dependent manner. Application of an adenosine A1 antagonist 1,3-dipropyl-8-cyclopentylxanthine produced a parallel rightward shift in the NBMPR concentration-effect curve. The effects of NBMPR were partially reversed by adenosine deaminase, which facilitates the metabolic degradation of adenosine. The modulation by NBMPR of evoked EPSCs was mimicked by exogenous adenosine or the selective A1 receptor agonist, 2-chloro-N6-cyclopentyl adenosine. NBMPR reduced the frequency but not the amplitude of spontaneous miniature EPSCs and increased the paired-pulse ratio of evoked currents, an effect that is consistent with presynaptic modulation. These data provide the first direct evidence that nucleoside transporters are able to critically modulate glutamatergic synaptic transmission. PMID:12611914

  4. Increased ability to induce long-term potentiation of spinal dorsal horn neurones in monoarthritic rats.

    PubMed

    Vikman, Kristina S; Duggan, Arthur W; Siddall, Philip J

    2003-11-14

    Long-term potentiation (LTP) of transmission of impulses in unmyelinated (C-fibre) primary afferents by prior tetanic conditioning stimulation has been demonstrated in the dorsal horn of the spinal cord. Since this potentiation has been proposed to be relevant to the increased responsiveness of spinal neurones associated with peripheral inflammation (central sensitisation), the present experiments compared the induction of LTP in normal rats and rats with monoarthritis. Monoarthritis was induced by injection of complete Freund's adjuvant (CFA) into the left ankle joint of 12 rats. All animals showed behavioural signs of thermal hyperalgesia and were used for electrophysiological experiments after 4-8 days. In each animal, extracellular recordings were obtained from a single, wide dynamic range (WDR) dorsal horn neurone. High frequency tetanic conditioning stimulation of the sciatic nerve gave varying effects on the C-fibre-evoked responses of neurones in the normal rats, with potentiation in two, no change in five and a depression in five. By contrast, conditioning stimulation in rats with inflammation produced a long-lasting potentiation of C-fibre-evoked responses in 11 out of 12 neurones, with no effect in one. The ease with which LTP was induced in animals with inflammation supports the proposal that the underlying mechanisms of LTP are similar to those of the central sensitisation associated with peripheral inflammation. PMID:14568329

  5. Reversal of neurochemical alterations in the spinal dorsal horn and dorsal root ganglia by Mas-related gene (Mrg) receptors in a rat model of spinal nerve injury.

    PubMed

    Wang, Dongmei; Xue, Yaping; Yan, Yanhua; Lin, Minjie; Yang, Jiajia; Huang, Jianzhong; Hong, Yanguo

    2016-07-01

    The rodent Mas-related gene (Mrg) receptor subtype C has been demonstrated to inhibit pathological pain. This study investigated the mechanisms underlying the reversal of pain hypersensitivity by the selective MrgC receptor agonist bovine adrenal medulla 8-22 (BAM8-22) in a rat model of L5 spinal nerve ligation (SNL). Intrathecal (i.t.) administration of BAM8-22 (0.1-10nmol) attenuated mechanical allodynia in a dose-dependent manner on day 10 after SNL. The antiallodynia effect of BAM8-22 was abolished by MrgC receptor antibody, but not by naloxone. I.t. BAM8-22 (10nmol) inhibited SNL-induced upregulation of neuronal nitric oxide synthesis (nNOS) and phosphorylation of cyclic AMP response element-binding protein (p-CREB) in the spinal dorsal horn. The BAM8-22 treatment reversed the SNL-induced astrocyte activation, increase of interleukin-1β (IL-1β) expression and phosphorylation of extracellular signal-regulated kinase (p-ERK) in the spinal cord. BAM8-22 also reversed the upregulation of fractalkine and IL-1β in small- and medium-sized dorsal root ganglion (DRG) neurons. Furthermore, the BAM8-22 exposure suppressed the lipopolysaccharide (LPS)-induced increase of nNOS and IL-1β in the DRG explant cultures and the BAM8-22-induced suppression disappeared in the presence of MrgC receptor antibody. The present study provides evidence that activation of MrgC receptors inhibits nerve injury-induced increase of pronociceptive molecules in DRG neurons, suppressing astrocyte activation, the upregulation of excitatory mediators and phosphorylation of transcription factors in the spinal dorsal horn. As MrgC receptors are unequally expressed in the dorsal root and trigeminal ganglia, this study suggests that targeting MrgC receptors could be a new therapy for neuropathic pain with limited unwanted effects. PMID:27018398

  6. Electrophysiological properties of rat spinal dorsal horn neurones in vitro: calcium-dependent action potentials.

    PubMed Central

    Murase, K; Randić, M

    1983-01-01

    1. The electrophysiological properties of dorsal horn neurones have been investigated in the immature rat in vitro spinal cord slice preparation. 2. Intracellular recordings from dorsal horn neurones show that direct or orthodromic stimulation generates action potentials followed by a brief after-hyperpolarization. Synaptic potentials were elicited by the activation of primary afferent fibres in the dorsal root. 3. Input resistance for dorsal horn neurones ranged from 48 to 267 M omega, and the membrane time constant was in the range of 4-19 ms. 4. In response to strong depolarizing currents dorsal horn neurones perfused with TTX and TEA frequently exhibit a slow regenerative depolarizing potential followed by a slow after-hyperpolarization. The depolarizing potential probably results from an influx of Ca. It is blocked by low concentration Ca, Co or Mn, and enhanced by high levels of extracellular Ca. 5. There is, in addition, a low-threshold Ca-dependent response which is activated at membrane potentials more negative than -65 mV and has a maximum rate of rise at the polarization level of about -80 mV. 6. The addition of Ba or TEA to the perfusing medium provided support for the Ca-dependence of the low- and high-threshold responses, and the lack of fast inactivation of the high-threshold Ca potential. Images Plate 1 PMID:6306228

  7. Both dorsal and ventral spinal cord pathways contribute to overground locomotion in the adult rat.

    PubMed

    Loy, David N; Talbott, Jason F; Onifer, Stephen M; Mills, Michael D; Burke, Darlene A; Dennison, Jessica B; Fajardo, Lili C; Magnuson, David S K; Whittemore, Scott R

    2002-10-01

    Identification of long tracts responsible for spontaneous locomotion is critical for spinal cord injury (SCI) repair strategies. We recently demonstrated that extensive demyelination of adult rat thoracic ventral columns, ventromedial, and ventrolateral white matter produces persistent, significant open-field hindlimb locomotor deficits. Locomotor movements resulting from stimulation of the pontomedullary locomotor region are inhibited by dorsolateral funiculus (DLF) lesions suggesting that important pathways for locomotion may also exist in the dorsal white matter. However, dorsal hemisections that interrupt dorsal columns/dorsal corticospinal tract (DC/CST) and DLF pathways do not produce persistent, severe locomotor deficits in the adult rat. We studied the contributions of myelinated tracts in the DLF and DC/CST to overground locomotion following complete conduction blockade of axons in the ventrolateral funiculus (VLF), a region important for locomotor movements and for transcranial magnetic motor-evoked potentials (tcMMEP). Animals received ethidium bromide plus photon irradiation to produce discrete demyelinating lesions sufficient to stop axonal conduction in the VLF, combined VLF + DLF, or combined VLF + DC/CST. Open-field BBB scores and tcMMEPs were studied at 1, 2, 3, and 4 weeks postlesion. VLF lesions resulted in mean BBB scores of 17 at 4 weeks. VLF + DC/CST and VLF + DLF lesions resulted in mean BBB scores of 15.9 and 11.1, respectively. TcMMEPs were absent in all lesion types confirming VLF conduction blockade throughout the study. Our data indicate that significant contributions to locomotion from myelinated pathways within the rat DLF can be revealed when combined with simultaneous compromise of the VLF. PMID:12429203

  8. Modulation of neuronal activity in dorsal column nuclei by upper cervical spinal cord stimulation in rats

    PubMed Central

    Qin, Chao; Yang, Xiaoli; Wu, Mingyuan; Farber, Jay P.; Linderoth, Bengt; Foreman, Robert D.

    2009-01-01

    Clinical human and animal studies show that upper cervical spinal cord stimulation (cSCS) has beneficial effects in treatment of some cerebral disorders, including those due to deficient cerebral circulation. However, the underlying mechanisms and neural pathways activated by cSCS using clinical parameters remain unclear. We have shown that a cSCS-induced increase in cerebral blood flow is mediated via rostral spinal dorsal column fibers implying that the dorsal column nuclei (DCNs) are involved. The aim of this study was to examine how cSCS modulated neuronal activity of DCNs.. A spring-loaded unipolar ball electrode was placed on the left dorsal column at cervical (C2) spinal cord in pentobarbital anesthetized, ventilated and paralyzed male rats. Stimulation with frequencies of 1, 10, 20, 50 Hz (0.2 ms, 10 s) and an intensity of 90% of motor threshold was applied. Extracellular potentials of single neurons in DCNs were recorded and examined for effects of cSCS. In total, 109 neurons in DCNs were isolated and tested for effects of cSCS. Out of these, 56 neurons were recorded from the cuneate nucleus and 53 from the gracile nucleus. Mechanical somatic stimuli altered activity of 87/109 (83.2%) examined neurons. Of the neurons receiving somatic input, 62 were classified as low-threshold and 25 as wide dynamic range. The cSCS at 1 Hz changed the activity of 96/109 (88.1%) of the neurons. Neuronal responses to cSCS exhibited multiple patterns of excitation and/or inhibition: excitation (E, n=21), inhibition (I, n=19), E-I (n=37), I-E (n=8) and E-I-E (n=11). Furthermore, cSCS with high-frequency (50 Hz) altered the activity of 92.7% (51/55) of tested neurons, including 30 E, 24 I, and 2 I-E responses to cSCS. These data suggested that cSCS significantly modulates neuronal activity in dorsal column nuclei. These nuclei might serve as a neural relay for cSCS-induced effects on cerebral dysfunction and diseases. PMID:19665525

  9. In vivo longitudinal Myelin Water Imaging in rat spinal cord following dorsal column transection injury.

    PubMed

    Kozlowski, Piotr; Rosicka, Paulina; Liu, Jie; Yung, Andrew C; Tetzlaff, Wolfram

    2014-04-01

    Longitudinal Myelin Water Imaging was carried out in vivo to characterize white matter damage following dorsal column transection (DC Tx) injury at the lumbar level L1 of rat spinal cords. A transmit-receive implantable coil system was used to acquire multiple spin-echo (MSE) quantitative T2 data from the lumbar spinal cords of 16 rats at one week pre-injury as well as 3 and 8weeks post-injury (117 microns in-plane resolution and 1.5mm slice thickness). In addition, ex vivo MSE and DTI data were acquired from cords fixed and excised at 3 or 8weeks post injury using a solenoid coil. The MSE data were used to generate Myelin Water Fractions (MWFs) as a surrogate measure of myelin content, while DTI data were acquired to study damage to the axons. Myelin damage was assessed histologically with Eriochrome cyanine (EC) and Myelin Basic Protein in degenerated myelin (dgen-MBP) staining, and axonal damage was assessed by neurofilament-H in combination with neuron specific beta-III-tubulin (NF/Tub) staining. These MRI and histological measures of injury were studied in the dorsal column at 5mm cranial and 5mm caudal to injury epicenter. MWF increased significantly at 3weeks post-injury at both the cranial and caudal sites, relative to baseline. The values on the cranial side of injury returned to baseline at 8weeks post-injury but remained elevated on the caudal side. This trend was found in both in vivo and ex vivo data. This MWF increase was likely due to the presence of myelin debris, which were cleared by 8 weeks on the cranial, but not the caudal, side. Both EC and dgen-MBP stains displayed similar trends. MWF showed significant correlation with EC staining (R=0.63, p=0.005 in vivo and R=0.74, p=0.0001 ex vivo). MWF also correlated strongly with the dgen-MBP stain, but only on the cranial side (R=0.64, p=0.05 in vivo; R=0.63, p=0.038 ex vivo). This study demonstrates that longitudinal MWI in vivo can accurately characterize white matter damage in DC Tx model of injury

  10. Propofol differentially inhibits the release of glutamate, γ-aminobutyric acid and glycine in the spinal dorsal horn of rats

    PubMed Central

    Yang, Jing; Wang, Wei; Yong, Zheng; Mi, Weidong; Zhang, Hong

    2015-01-01

    Objective(s): Propofol (2, 6-diisopropylphenol) is an intravenous anesthetic that is commonly used for the general anesthesia. It is well known that the spinal cord is one of the working targets of general anesthesia including propofol. However, there is a lack of investigation of the effects of propofol on spinal dorsal horn which is important for the sensory transmission of nociceptive signals. The objective of this study was to investigate the effects of increasing dosage of propofol on the release of glutamate (Glu), γ-aminobutyric acid (GABA) and glycine (Gly) in the spinal dorsal horn. Materials and Methods: The efflux of Glu, GABA or Gly in the spinal dorsal horn of rats was detected using transverse spinal microdialysis under an awake condition and various depths of propofol anesthesia. The infusion rates of propofol were, in order, 400 µg/(kg·min), 600 µg/(kg·min) and 800 µg/(kg·min), with a 20 min infusion period being maintained at each infusion rate. Results: Propofol decreased the glutamate efflux within spinal dorsal horn in a dose-dependent manner, and the maximum decrease was 56.8 ± 6.0% at high-dose propofol infusion producing immobility. The inhibitory GABA and Gly efflux was also decreased about 15–20% at low-dose propofol infusion only producing sedation, but did not continue to drop with higher doses of propofol. Conclusion: Propofol decreased both excitatory and inhibitory amino acids efflux in spinal dorsal horn, and the preferential suppression of the excitatory amino acid might be associated with the analgesic effect of propofol. PMID:26557972

  11. Modulation of Spinal GABAergic Inhibition and Mechanical Hypersensitivity following Chronic Compression of Dorsal Root Ganglion in the Rat

    PubMed Central

    Lee, Moon Chul; Nam, Taick Sang; Jung, Se Jung; Gwak, Young S.; Leem, Joong Woo

    2015-01-01

    Chronic compression of dorsal root ganglion (CCD) results in neuropathic pain. We investigated the role of spinal GABA in CCD-induced pain using rats with unilateral CCD. A stereological analysis revealed that the proportion of GABA-immunoreactive neurons to total neurons at L4/5 laminae I–III on the injured side decreased in the early phase of CCD (post-CCD week 1) and then returned to the sham-control level in the late phase (post-CCD week 18). In the early phase, the rats showed an increase in both mechanical sensitivity of the hind paw and spinal WDR neuronal excitability on the injured side, and such increase was suppressed by spinally applied muscimol (GABA-A agonist, 5 nmol) and baclofen (GABA-B agonist, 25 nmol), indicating the reduced spinal GABAergic inhibition involved. In the late phase, the CCD-induced increase in mechanical sensitivity and neuronal excitability returned to pre-CCD levels, and such recovered responses were enhanced by spinally applied bicuculline (GABA-A antagonist, 15 nmol) and CGP52432 (GABA-B antagonist, 15 nmol), indicating the regained spinal GABAergic inhibition involved. In conclusion, the alteration of spinal GABAergic inhibition following CCD and leading to a gradual reduction over time of CCD-induced mechanical hypersensitivity is most likely due to changes in GABA content in spinal GABA neurons. PMID:26451259

  12. Functional differences between neurochemically defined populations of inhibitory interneurons in the rat spinal dorsal horn☆

    PubMed Central

    Polgár, Erika; Sardella, Thomas C.P.; Tiong, Sheena Y.X.; Locke, Samantha; Watanabe, Masahiko; Todd, Andrew J.

    2013-01-01

    In order to understand how nociceptive information is processed in the spinal dorsal horn we need to unravel the complex synaptic circuits involving interneurons, which constitute the vast majority of the neurons in laminae I–III. The main limitation has been the difficulty in defining functional populations among these cells. We have recently identified 4 non-overlapping classes of inhibitory interneuron, defined by expression of galanin, neuropeptide Y (NPY), neuronal nitric oxide synthase (nNOS) and parvalbumin, in the rat spinal cord. In this study we demonstrate that these form distinct functional populations that differ in terms of sst2A receptor expression and in their responses to painful stimulation. The sst2A receptor was expressed by nearly all of the nNOS- and galanin-containing inhibitory interneurons but by few of those with NPY and none of the parvalbumin cells. Many galanin- and NPY-containing cells exhibited phosphorylated extracellular signal-regulated kinases (pERK) after mechanical, thermal or chemical noxious stimuli, but very few nNOS-containing cells expressed pERK after any of these stimuli. However, many nNOS-positive inhibitory interneurons up-regulated Fos after noxious thermal stimulation or injection of formalin, but not after capsaicin injection. Parvalbumin cells did not express either activity-dependent marker following any of these stimuli. These results suggest that interneurons belonging to the NPY, nNOS and galanin populations are involved in attenuating pain, and for NPY and nNOS cells this is likely to result from direct inhibition of nociceptive projection neurons. They also suggest that the nociceptive inputs to the nNOS cells differ from those to the galanin and NPY populations. PMID:23707280

  13. Evidence that dorsal locus coeruleus neurons can maintain their spinal cord projection following neonatal transection of the dorsal adrenergic bundle in rats.

    PubMed

    Stanfield, B B

    1989-01-01

    In adult rats, locus coeruleus neurons which extend axons to the spinal cord are found only at mid-rostrocaudal levels of the nucleus, where they are essentially confined to its ventral, wedge-shaped half (Satoh et al. 1980; Westlund et al. 1983; Loughlin et al. 1986). However, during early postnatal development, coeruleospinal cells are found throughout the locus coeruleus (Cabana and Martin 1984; Chen and Stanfield 1987). This developmental restriction of the distribution of coeruleospinal neurons is due to axonal elimination rather than to cell death, since neurons retrogradely labeled through their spinal axons perinatally are still present in the dorsal portion of the locus coeruleus at survival periods beyond the age at which these cells lose their spinal projection (Chen and Stanfield 1987). I now report that if axons ascending from the locus coeruleus are cut by transecting the dorsal adrenergic bundle on the day of birth, a more widespread distribution of coeruleospinal neurons is retained beyond the perinatal period. These results not only indicate that the absence of the normally maintained collateral of a locus coeruleus neuron is sufficient to prevent the elimination of a collateral which would otherwise be lost, but also may imply that during normal postnatal development the presence of the maintained collateral is somehow causally involved in the elimination of the transient collateral. PMID:2612596

  14. Silent NMDA receptor-mediated synapses are developmentally regulated in the dorsal horn of the rat spinal cord.

    PubMed

    Baba, H; Doubell, T P; Moore, K A; Woolf, C J

    2000-02-01

    In vitro whole cell patch-clamp recording techniques were utilized to study silent pure-N-methyl-D-aspartate (NMDA) receptor-mediated synaptic responses in lamina II (substantia gelatinosa, SG) and lamina III of the spinal dorsal horn. To clarify whether these synapses are present in the adult and contribute to neuropathic pain, transverse lumbar spinal cord slices were prepared from neonatal, naive adult and adult sciatic nerve transected rats. In neonatal rats, pure-NMDA receptor-mediated excitatory postsynaptic currents (EPSCs) were elicited in SG neurons either by focal intraspinal stimulation (n = 15 of 20 neurons) or focal stimulation of the dorsal root (n = 2 of 7 neurons). In contrast, in slices from naive adult rats, no silent pure-NMDA EPSCs were recorded in SG neurons following focal intraspinal stimulation (n = 27), and only one pure-NMDA EPSC was observed in lamina III (n = 23). Furthermore, in rats with chronic sciatic nerve transection, pure-NMDA EPSCs were elicited by focal intraspinal stimulation in only 2 of 45 SG neurons. Although a large increase in Abeta fiber evoked mixed alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and NMDA receptor-mediated synapses was detected after sciatic nerve injury, Abeta fiber-mediated pure-NMDA EPSCs were not evoked in SG neurons by dorsal root stimulation. Pure-NMDA receptor-mediated EPSCs are therefore a transient, developmentally regulated phenomenon, and, although they may have a role in synaptic refinement in the immature dorsal horn, they are unlikely to be involved in receptive field plasticity in the adult. PMID:10669507

  15. Glial nitric oxide-mediated long-term presynaptic facilitation revealed by optical imaging in rat spinal dorsal horn.

    PubMed

    Ikeda, Hiroshi; Murase, Kazuyuki

    2004-11-01

    We investigated a presynaptic form of long-term potentiation (LTP) in horizontal slices of the rat spinal cord by visualizing presynaptic and postsynaptic excitation with a voltage-sensitive dye. To record presynaptic excitation, we stained primary afferent fibers anterogradely from the dorsal root. A single-pulse test stimulation of C fiber-activating strength to the dorsal root elicited action potential (AP)-like or compound AP-like optical signals throughout the superficial dorsal horn. After conditioning (240 pulses at 2 Hz for 2 min), the presynaptic excitation was augmented. Furthermore, new excitation was elicited in the areas that were silent before conditioning. For postsynaptic recording, projection neurons in spinal lamina I were stained retrogradely from the periaqueductal gray in the brain stem. The test stimulation elicited AP-like or EPSP-like optical signals in the stained neurons. After conditioning, the EPSP-like responses were augmented, and previously silent neurons were converted to active ones. Results obtained with a nitric oxide (NO) donor, NO synthase inhibitors, metabotropic glutamate receptor (mGluR) agonist and mGluR1 antagonist, and a glial metabolism inhibitor suggest that after conditioning, presynaptic excitation is facilitated by NO released from glial cells via the activation of mGluR1. The results also indicate the possible presence of additional presynaptic and postsynaptic mechanism(s) for the LTP induction. Activity-dependent LTP of nociceptive afferent synaptic transmission in the spinal cord is believed to underlie central sensitization after inflammation or nerve injury. This glial NO-mediated control of presynaptic excitation may contribute to the induction at least in part. PMID:15525773

  16. Inflammation alters trafficking of extrasynaptic AMPA receptors in tonically firing lamina II neurons of the rat spinal dorsal horn

    PubMed Central

    Kopach, Olga; Kao, Sheng-Chin; Petralia, Ronald S.; Belan, Pavel; Tao, Yuan-Xiang; Voitenko, Nana

    2011-01-01

    Peripheral inflammation alters AMPA receptor (AMPAR) subunit trafficking and increases AMPAR Ca2+ permeability at synapses of spinal dorsal horn neurons. However, it is unclear whether AMPAR trafficking at extrasynaptic sites of these neurons also changes under persistent inflammatory pain conditions. Using patch-clamp recording combined with Ca2+ imaging and cobalt staining, we found that, under normal conditions, an extrasynaptic pool of AMPARs in rat substantia gelatinosa (SG) neurons of spinal dorsal horn predominantly consists of GluR2-containing Ca2+-impermeable receptors. Maintenance of complete Freund’s adjuvant (CFA)-induced inflammation was associated with a marked enhancement of AMPA-induced currents and [Ca2+]i transients in SG neurons, while, as we previously showed, the amplitude of synaptically evoked AMPAR-mediated currents was not changed 24 h after CFA. These findings indicate that extrasynaptic AMPARs are upregulated and their Ca2+ permeability increases dramatically. This increase occurred in SG neurons characterized by intrinsic tonic firing properties, but not in those exhibited strong adaptation. This increase was also accompanied by an inward rectification of AMPA-induced currents and enhancement of sensitivity to a highly selective Ca2+-permeable AMPAR blocker, IEM-1460. Electron microcopy and biochemical assays additionally showed an increase in the amount of GluR1 at extrasynaptic membranes in dorsal horn neurons 24 h post-CFA. Taken together, our findings suggest that CFA-induced inflammation increases functional expression and proportion of extrasynaptic GluR1-containing Ca2+-permeable AMPARs in tonically firing excitatory dorsal horn neurons. We suggest that the altered extrasynaptic AMPAR trafficking might participate in the maintenance of persistent inflammatory pain. PMID:21282008

  17. Inflammation alters trafficking of extrasynaptic AMPA receptors in tonically firing lamina II neurons of the rat spinal dorsal horn.

    PubMed

    Kopach, Olga; Kao, Sheng-Chin; Petralia, Ronald S; Belan, Pavel; Tao, Yuan-Xiang; Voitenko, Nana

    2011-04-01

    Peripheral inflammation alters AMPA receptor (AMPAR) subunit trafficking and increases AMPAR Ca(2+) permeability at synapses of spinal dorsal horn neurons. However, it is unclear whether AMPAR trafficking at extrasynaptic sites of these neurons also changes under persistent inflammatory pain conditions. Using patch-clamp recording combined with Ca(2+) imaging and cobalt staining, we found that, under normal conditions, an extrasynaptic pool of AMPARs in rat substantia gelatinosa (SG) neurons of spinal dorsal horn predominantly consists of GluR2-containing Ca(2+)-impermeable receptors. Maintenance of complete Freund's adjuvant (CFA)-induced inflammation was associated with a marked enhancement of AMPA-induced currents and [Ca(2+)](i) transients in SG neurons, while, as we previously showed, the amplitude of synaptically evoked AMPAR-mediated currents was not changed 24 h after CFA. These findings indicate that extrasynaptic AMPARs are upregulated and their Ca(2+) permeability increases dramatically. This increase occurred in SG neurons characterized by intrinsic tonic firing properties, but not in those exhibited strong adaptation. This increase was also accompanied by an inward rectification of AMPA-induced currents and enhancement of sensitivity to a highly selective Ca(2+)-permeable AMPAR blocker, IEM-1460. Electron microcopy and biochemical assays additionally showed an increase in the amount of GluR1 at extrasynaptic membranes in dorsal horn neurons 24h post-CFA. Taken together, our findings indicate that CFA-induced inflammation increases functional expression and proportion of extrasynaptic GluR1-containing Ca(2+)-permeable AMPARs in tonically firing excitatory dorsal horn neurons, suggesting that the altered extrasynaptic AMPAR trafficking might participate in the maintenance of persistent inflammatory pain. PMID:21282008

  18. Direct communication of the spinal subarachnoid space with the rat dorsal root ganglia.

    PubMed

    Joukal, Marek; Klusáková, Ilona; Dubový, Petr

    2016-05-01

    The anatomical position of the subarachnoid space (SAS) in relation to dorsal root ganglia (DRG) and penetration of tracer from the SAS into DRG were investigated. We used intrathecal injection of methylene blue to visualize the anatomical position of the SAS in relation to DRG and immunostaining of dipeptidyl peptidase IV (DPP-IV) for detecting arachnoid limiting the SAS. Intrathecal administration of fluorescent-conjugated dextran (fluoro-emerald; FE) was used to demonstrate direct communication between the SAS and DRG. Intrathecal injection of methylene blue and DPP-IV immunostaining revealed that SAS delimited by the arachnoid was extended up to the capsule of DRG in a fold-like recess that may reach approximately half of the DRG length. The arachnoid was found in direct contact to the neuronal body-rich area in the angle between dorsal root and DRG as well as between spinal nerve roots at DRG. Particles of FE were found in the cells of DRG capsule, satellite glial cells, interstitial space, as well as in small and medium-sized neurons after intrathecal injection. Penetration of FE from the SAS into the DRG induced an immune reaction expressed by colocalization of FE and immunofluorescence indicating antigen-presenting cells (MHC-II+), activated (ED1+) and resident (ED2+) macrophages, and activation of satellite glial cells (GFAP+). Penetration of lumbar-injected FE into the cervical DRG was greater than that into the lumbar DRG after intrathecal injection of FE into the cisterna magna. Our results demonstrate direct communication between DRG and cerebrospinal fluid in the SAS that can create another pathway for possible propagation of inflammatory and signaling molecules from DRG primary affected by peripheral nerve injury into DRG of remote spinal segments. PMID:26844624

  19. Downregulation of Cdh1 signalling in spinal dorsal horn contributes to the maintenance of mechanical allodynia after nerve injury in rats

    PubMed Central

    Hu, Rong; Li, Li; Li, Dajia; Tan, Wei; Wan, Li; Zhu, Chang; Zhang, Yue; Zhang, Chuanhan

    2016-01-01

    Background Anaphase-promoting complex/cyclosome (APC/C) and its co-activator Cdh1 are important ubiquitin-ligases in proliferating cells and terminally differentiated neurons. In recent years, APC/C-Cdh1 has been reported as an important complex contributing to synaptic development and transmission. Interestingly, cortical APC/C-Cdh1 is found to play a critical role in the maintenance of neuropathic pain, but it is not clear whether APC/C-Cdh1 in spinal dorsal cord is involved in molecular mechanisms of neuropathic pain conditions. Results Immunostaining showed that Cdh1 was mainly distributed in dorsal horn neurons of the spinal cord in rats. Its expression was downregulated in the ipsilateral dorsal horn at 14 days after spared nerve injury. Rescued expression of Cdh1 in spinal cord by intrathecal administration of recombinant lentivirus encoding Cdh1 (Lenti-Cdh1-GFP) significantly attenuated spared nerve injury-induced mechanical allodynia. Furthermore, rescued expression of spinal Cdh1 significantly reduced surface membrane expression of GluR1, but increased the expression of GluR1-related erythropoietin-producing human hepatocellular receptor A4 and its ligand EphrinA1 in dorsal horn of spared nerve injury-treated animals. Conclusions This study indicates that a downregulation of Cdh1 expression in spinal dorsal horn is involved in molecular mechanisms underlying the maintenance of neuropathic pain. Upregulation of spinal Cdh1 may be a promising approach to treat neuropathic pain. PMID:27184142

  20. Dorsal-ventral differences in the glia limitans of the spinal cord: an ultrastructural study in developing normal and irradiated rats

    SciTech Connect

    Sims, T.J.; Gilmore, S.A.; Waxman, S.G.; Klinge, E.

    1985-07-01

    The dorsal and ventral surfaces of the lumbosacral spinal cord were examined in normal and irradiated postnatal rats. In normal rats between three and 13 days postnatal (DP), the glia limitans (GL) of the ventral surface was a more complex structure than the dorsal GL. This greater degree of complexity was manifested in a greater number of subpial astrocytes, a greater number of radial glial processes and a more advanced state in differentiation of its constituents. In rats irradiated at three DP and examined at 13 DP, the ventral GL remained intact and relatively unaffected by the radiation. In contrast, the dorsal GL was disrupted, and Schwann cells were seen within the dorsal funiculus. The ventral GL of the rat lumbosacral spinal cord is a more substantial structure than the dorsal GL during normal development. This factor alone may account for the integrity of the barrier properties of the ventral GL following radiation. However, these observations suggest that subpial astrocytes of the dorsal GL are more susceptible to radiation damage at three DP than the subpial astrocytes and radial glia of the ventral GL.

  1. Characteristics of the electrical oscillations evoked by 4-aminopyridine on dorsal root fibers and their relation to fictive locomotor patterns in the rat spinal cord in vitro.

    PubMed

    Taccola, G; Nistri, A

    2005-01-01

    4-Aminopyridine (4-AP) is suggested to improve symptomatology of spinal injury patients because it may facilitate neuromuscular transmission, spinal impulse flow and the operation of the locomotor central pattern generator (CPG). Since 4-AP can also induce repetitive discharges from dorsal root afferents, this phenomenon might interfere with sensory signals necessary to modulate CPG activity. Using electrophysiological recording from dorsal and ventral roots of the rat isolated spinal cord, we investigated 4-AP-evoked discharges and their relation with fictive locomotor patterns. On dorsal roots 4-AP (5-10 microM) induced sustained synchronous oscillations (3.3+/-0.8 s period) smaller than electrically evoked synaptic potentials, persistent after sectioning off the ventral region and preserved in an isolated dorsal quadrant, indicating their dorsal horn origin. 4-AP oscillations were blocked by tetrodotoxin, or 6-cyano-7-nitroquinoxaline-2,3-dione and d-amino-phosphonovalerate, or strychnine and bicuculline, suggesting they were network mediated via glutamatergic, glycinergic and GABAergic transmission. Isolated ventral horn areas could not generated 4-AP oscillations, although their intrinsic disinhibited bursting was accelerated by 4-AP. Thus, ventral horn areas contained 4-AP sensitive sites, yet lacked the network for 4-AP induced oscillations. Activation of fictive locomotion by either application of N-methyl-D-aspartate and serotonin or stimulus trains to a single dorsal root reversibly suppressed dorsal root oscillations induced by 4-AP. This suppression was due to depression of dorsal network activity rather than simple block of root discharges. Since dorsal root oscillations evoked by 4-AP were turned off when the fictive locomotor program was initiated, these discharges are unlikely to interfere with proprioceptive signals during locomotor training in spinal patients. PMID:15857720

  2. Serotonin Concentrations in the Lumbosacral Spinal Cord of the Adult Rat Following Microinjection or Dorsal Surface Application

    PubMed Central

    Brumley, Michele R.; Hentall, Ian D.; Pinzon, Alberto; Kadam, Brijesh H.; Blythe, Anthony; Sanchez, Francisco J.; Taberner, Annette M.; Noga, Brian R.

    2009-01-01

    Application of neuroactive substances, including monoamines, is common in studies examining the spinal mechanisms of sensation and behavior. However, affected regions and time courses of transmitter activity are uncertain. We measured the spatial and temporal distribution of serotonin [5-hydroxytryptamine (5-HT)] in the lumbosacral spinal cord of halothane-anesthetized adult rats, following its intraspinal microinjection or surface application. Carbon fiber microelectrodes (CFMEs) were positioned at various locations in the spinal cord and oxidation currents corresponding to extracellular 5-HT were measured by fast cyclic voltammetry. Intraspinal microinjection of 5-HT (100μM, 1–3 μl) produced responses that were most pronounced at CFMEs positioned ≤800 μm from the drug micropipette: 5-HT concentration was significantly higher (1.43 vs. <0.28% of initial concentration) and response latency was shorter (67.1 vs. 598.2 s) compared with more distantly positioned CFMEs. Treatment with the selective 5-HT reuptake inhibitor clomipramine only slightly affected the spread of microinjected 5-HT. Surface application over several segments led to a transient rise in concentration that was usually apparent within 30 s and was dramatically attenuated with increasing depth: 0.25% of initial concentration (1 mM) within 400 μm of the dorsal surface and <0.001% between 1,170 and 2,000 μm. This initial response to superfusion was sometimes followed by a gradual increase to a new concentration plateau. In sum, compared with bath application, microinjection can deliver about tenfold higher transmitter concentrations, but to much more restricted areas of the spinal cord. PMID:17634342

  3. Stimulation of the ventral tegmental area increased nociceptive thresholds and decreased spinal dorsal horn neuronal activity in rat.

    PubMed

    Li, Ai-Ling; Sibi, Jiny E; Yang, Xiaofei; Chiao, Jung-Chih; Peng, Yuan Bo

    2016-06-01

    Deep brain stimulation has been found to be effective in relieving intractable pain. The ventral tegmental area (VTA) plays a role not only in the reward process, but also in the modulation of nociception. Lesions of VTA result in increased pain thresholds and exacerbate pain in several pain models. It is hypothesized that direct activation of VTA will reduce pain experience. In this study, we investigated the effect of direct electrical stimulation of the VTA on mechanical, thermal and carrageenan-induced chemical nociceptive thresholds in Sprague-Dawley rats using our custom-designed wireless stimulator. We found that: (1) VTA stimulation itself did not show any change in mechanical or thermal threshold; and (2) the decreased mechanical and thermal thresholds induced by carrageenan injection in the hind paw contralateral to the stimulation site were significantly reversed by VTA stimulation. To further explore the underlying mechanism of VTA stimulation-induced analgesia, spinal cord dorsal horn neuronal responses to graded mechanical stimuli were recorded. VTA stimulation significantly inhibited dorsal horn neuronal activity in response to pressure and pinch from the paw, but not brush. This indicated that VTA stimulation may have exerted its analgesic effect via descending modulatory pain pathways, possibly through its connections with brain stem structures and cerebral cortex areas. PMID:26821313

  4. Activation of presynaptic glycine receptors facilitates glycine release from presynaptic terminals synapsing onto rat spinal sacral dorsal commissural nucleus neurons

    PubMed Central

    Jeong, Hyo-Jin; Jang, Il-Sung; Moorhouse, Andrew J; Akaike, Norio

    2003-01-01

    Glycine is a major inhibitory neurotransmitter in the spinal cord and brainstem. Here we report the novel finding that presynaptic glycine autoreceptors modulate release from terminals synapsing onto rat spinal sacral dorsal commissural nucleus (SDCN) neurons. In mechanically dissociated SDCN neurons, in which functional presynaptic nerve terminals remain adherent to the isolated neurons, exogenously applied glycine (3 μM) increased the frequency of glycinergic spontaneous inhibitory postsynaptic currents (sIPSCs) without affecting their amplitudes or decay times. This suggests that glycine acts presynaptically to increase glycine release probability. Picrotoxin, at a concentration that had little direct effect on sIPSC frequency and amplitude (30 μM), significantly attenuated glycine-induced presynaptic sIPSC facilitation. The glycine-induced sIPSC frequency facilitation was completely abolished either in a Ca2+-free external solution or in the presence of 100 μM Cd2+, suggesting the involvement of extracellular Ca2+ influx into the nerve terminals. The glycine action was also completely occluded in the presence of 300 nM tetrodotoxin. In recordings from SDCN neurons in spinal cord slices, glycine (10 μM) increased evoked IPSC (eIPSC) amplitude and decreased the extent of paired-pulse facilitation. In response to brief high frequency stimulus trains the eIPSCs displayed a profound frequency-dependent facilitation that was greatly reduced by picrotoxin (30 μM). These results indicate that glycine acts at presynaptic autoreceptors, causing depolarization of the glycinergic nerve terminals, the subsequent activation of voltage-dependent Na+ and Ca2+ channels, and facilitation of glycine release. Furthermore, this presynaptic facilitation was observed under more physiological conditions, suggesting that these glycinergic autoreceptors may contribute to the integration of local inhibitory inputs to SDCN neurons. PMID:12754315

  5. Long-term potentiation of neuronal excitation by neuron-glia interactions in the rat spinal dorsal horn.

    PubMed

    Ikeda, Hiroshi; Tsuda, Makoto; Inoue, Kazuhide; Murase, Kazuyuki

    2007-03-01

    By imaging neuronal excitation in rat spinal cord slices with a voltage-sensitive dye, we examined the role of glial cells in the P2X receptor agonist alphabeta-methylene ATP (alphabetameATP)-triggered long-term potentiation (LTP) in the dorsal horn. Bath application of alphabetameATP potentiated neuronal excitation in the superficial dorsal horn. The potentiation was inhibited in the presence of the P2X receptor antagonists TNP-ATP, PPADS and A-317491, and was not induced in slices taken from rats neonatally treated with capsaicin. These results suggest that alphabetameATP acts on P2X receptors, possibly P2X(3) and/or P2X(2/3), in capsaicin-sensitive primary afferent terminals. Furthermore, the potentiation was inhibited by treatment with the glial metabolism inhibitor monofluoroacetic acid. Results obtained with the p38 mitogen-activated protein kinase (p38 MAPK) inhibitor SB203580, tumour necrosis factor-alpha (TNF-alpha) and interleukin (IL)-6, and antibodies to TNF-alpha and IL-6, as well as by double immunolabelling of activated p38 MAPK with markers of astrocytes and microglia, demonstrated that alphabetameATP activated p38 MAPK in astrocytes, and that the presence of proinflammatory cytokines and p38 MAPK activation were necessary for the induction of alphabetameATP-triggered LTP. These findings indicate that glial cells contribute to the alphabetameATP-induced LTP, which might be part of a cellular mechanism for the induction of persistent pain. PMID:17425556

  6. Impacts of anti-nerve growth factor antibody on pain-related behaviors and expressions of opioid receptor in spinal dorsal horn and dorsal root ganglia of rats with cancer-induced bone pain

    PubMed Central

    Ding, Yuanyuan; Wang, Zhibin; Ma, Jiaming; Hong, Tao; Zhu, Yongqiang; Li, Hongxi; Pan, Shinong

    2016-01-01

    Objective To investigate the impacts of anti-nerve growth factor antibody on pain-related behaviors and expressions of μ-opioid receptor in spinal dorsal horn and dorsal root ganglia of rats with cancer-induced bone pain. Methods The rats were randomly grouped and then injected with 10 μl of phosphate buffer saline or Walker256 tumor cells into the upper segment of left tibia. Thirteen days after the injection, the intrathecal catheterization was performed, followed by the injection of saline, anti-nerve growth factor, nerve growth factor, and naloxone twice a day. The pain ethological changes were measured at the set time points; the expression changes of μ-opioid receptor protein and mRNA in spinal dorsal horn and dorsal root ganglia were detected on the 18th day. Results After the tumor cells were injected into the tibia, hyperalgesia appeared and the expression of μ-opioid receptor protein and mRNA in spinal dorsal horn and dorsal root ganglia was increased, compared with the sham group; after intrathecally injected anti-nerve growth factor, the significant antinociceptive effects appeared, and the μ-opioid receptor expression was increased, compared with the cancer pain group; the μ-opioid receptor expressions in the other groups showed no statistical significance. The naloxone pretreatment could mostly inverse the antinociception effects of anti-nerve growth factor. Conclusions Anti-nerve growth factor could reduce hyperalgesia in the cancer-induced bone pain rats, and the antinociceptive effects were related with the upregulation of μ-opioid receptor. PMID:27118770

  7. Regulation by equilibrative nucleoside transporter of adenosine outward currents in adult rat spinal dorsal horn neurons.

    PubMed

    Liu, Tao; Fujita, Tsugumi; Kawasaki, Yasuhiko; Kumamoto, Eiichi

    2004-07-30

    A current response induced by superfusing adenosine was examined in substantia gelatinosa (SG) neurons of adult rat spinal cord slices by using the whole-cell patch-clamp technique. In 78% of the neurons examined, adenosine induced an outward current at -70 mV [18.8 +/- 1.1 pA (n = 98) at 1mM] in a dose-dependent manner (EC(50) = 177 microM). A similar current was induced by A(1) agonist N(6)-cyclopentyladenosine (1 microM), whereas A(1) antagonist 8-cyclopentyl-1,3-dipropylxanthine (1 microM) reversed the adenosine action. The adenosine current reversed its polarity at a potential being close to the equilibrium potential for K(+), and was attenuated by Ba(2+) (100 microM) and 4-aminopyridine (5mM) but not tetraethylammonium (5mM). The adenosine current was enhanced in duration by equilibrative nucleoside-transport (rENT1) inhibitor S-(4-nitrobenzyl)-6-thioinosine (1 microM) and adenosine deaminase (ADA) inhibitor erythro-9-(2-hydroxy-3-nonyl) adenine (1 microM), and slowed in falling phase by adenosine kinase (AK) inhibitor iodotubercidine (1 microM). We conclude that a Ba(2+)- and 4-aminopyridine-sensitive K(+) channel in SG neurons is opened via the activation of A(1) receptors by adenosine whose level is possibly regulated by rENT1, adenosine deaminase and adenosine kinase. Considering that intrathecally-administered adenosine analogues produce antinociception, the regulatory systems of adenosine may serve as targets for antinociceptive drugs. PMID:15275960

  8. Minocycline enhances inhibitory transmission to substantia gelatinosa neurons of the rat spinal dorsal horn.

    PubMed

    Peng, H-Z; Ma, L-X; Lv, M-H; Hu, T; Liu, T

    2016-04-01

    Minocycline, a second-generation tetracycline, is well known for its antibiotic, anti-inflammatory, and antinociceptive effects. Modulation of synaptic transmission is one of the analgesic mechanisms of minocycline. Although it has been reported that minocycline may suppress excitatory glutamatergic synaptic transmission, it remains unclear whether it could affect inhibitory synaptic transmission, which also plays a key role in modulating pain signaling. To examine the effect of minocycline on synaptic transmission in rat spinal substantia gelatinosa (SG) neurons, we recorded spontaneous inhibitory postsynaptic currents (sIPSCs) using whole-cell patch-clamp recording at a holding potential of 0 mV. Bath application of minocycline significantly increased the frequency but not the amplitude of sIPSCs in a reversible and concentration-dependent manner with an EC50 of 85. The enhancement of inhibitory synaptic transmission produced by minocycline was not affected by the glutamate receptor antagonists CNQX and D-APV or by the voltage-gated sodium channel blocker tetrodotoxin (TTX). Moreover, the potency of minocycline for facilitating sIPSC frequency was the same in both glycinergic and GABAergic sIPSCs without changing their decay phases. However, the facilitatory effect of minocycline on sIPSCs was eliminated in a Ca(2+)-free Krebs solution or by co-administration with calcium channel blockers. In summary, our data demonstrate that baseline inhibitory synaptic transmission in SG neurons is markedly enhanced by minocycline. This may function to decrease the excitability of SG neurons, thus leading to a modulation of nociceptive transmission. PMID:26826332

  9. Differential expression patterns of K(+) /Cl(-) cotransporter 2 in neurons within the superficial spinal dorsal horn of rats.

    PubMed

    Javdani, Fariba; Holló, Krisztina; Hegedűs, Krisztina; Kis, Gréta; Hegyi, Zoltán; Dócs, Klaudia; Kasugai, Yu; Fukazawa, Yugo; Shigemoto, Ryuichi; Antal, Miklós

    2015-09-01

    γ-Aminobutyric acid (GABA)- and glycine-mediated hyperpolarizing inhibition is associated with a chloride influx that depends on the inwardly directed chloride electrochemical gradient. In neurons, the extrusion of chloride from the cytosol primarily depends on the expression of an isoform of potassium-chloride cotransporters (KCC2s). KCC2 is crucial in the regulation of the inhibitory tone of neural circuits, including pain processing neural assemblies. Thus we investigated the cellular distribution of KCC2 in neurons underlying pain processing in the superficial spinal dorsal horn of rats by using high-resolution immunocytochemical methods. We demonstrated that perikarya and dendrites widely expressed KCC2, but axon terminals proved to be negative for KCC2. In single ultrathin sections, silver deposits labeling KCC2 molecules showed different densities on the surface of dendritic profiles, some of which were negative for KCC2. In freeze fracture replicas and tissue sections double stained for the β3-subunit of GABAA receptors and KCC2, GABAA receptors were revealed on dendritic segments with high and also with low KCC2 densities. By measuring the distances between spots immunoreactive for gephyrin (a scaffolding protein of GABAA and glycine receptors) and KCC2 on the surface of neurokinin 1 (NK1) receptor-immunoreactive dendrites, we found that gephyrin-immunoreactive spots were located at various distances from KCC2 cotransporters; 5.7 % of them were recovered in the middle of 4-10-µm-long dendritic segments that were free of KCC2 immunostaining. The variable local densities of KCC2 may result in variable postsynaptic potentials evoked by the activation of GABAA and glycine receptors along the dendrites of spinal neurons. PMID:25764511

  10. Differences in Neural-Immune Gene Expression Response in Rat Spinal Dorsal Horn Correlates with Variations in Electroacupuncture Analgesia

    PubMed Central

    Xiang, Xiaohui; He, Fei; Lin, Libo; Ping, Xingjie; Yu, Lei; Han, Jisheng; Zhao, Guoping; Zhang, Qinghua; Cui, Cailian

    2012-01-01

    Background Electroacupuncture (EA) has been widely used to alleviate diverse pains. Accumulated clinical experiences and experimental observations indicated that significant differences exist in sensitivity to EA analgesia for individuals of patients and model animals. However, the molecular mechanism accounting for this difference remains obscure. Methodology/Principal Findings We classified model male rats into high-responder (HR; TFL changes >150) and non-responder (NR; TFL changes ≤0) groups based on changes of their pain threshold detected by tail-flick latency (TFL) before and after 2 Hz or 100 Hz EA treatment. Gene expression analysis of spinal dorsal horn (DH) revealed divergent expression in HR and NR after 2 Hz/100 Hz EA. The expression of the neurotransmitter system related genes was significantly highly regulated in the HR animals while the proinflammation cytokines related genes were up-regulated more significantly in NR than that in HR after 2 Hz and 100 Hz EA stimulation, especially in the case of 2 Hz stimulation. Conclusions/Significance Our results suggested that differential regulation and coordination of neural-immune related genes might play an important role for individual variations in analgesic effects responding to EA in DH. It also provided new candidate genes related to EA responsiveness for future investigation. PMID:22879942

  11. Cortical and subcortical plasticity in the brains of humans, primates, and rats after damage to sensory afferents in the dorsal columns of the spinal cord

    PubMed Central

    Kaas, Jon H.; Qi, Hui-Xin; Burish, Mark; Gharbawie, Omar; Onifer, Stephen M.; Massey, James M.

    2008-01-01

    The failure of injured axons to regenerate following spinal cord injury deprives brain neurons of their normal sources of activation. These injuries also result in the reorganization of affected areas of the central nervous system that is thought to drive both the ensuing recovery of function and the formation of maladaptive neuronal circuitry. Better understanding of the physiological consequences of novel synaptic connections produced by injury and the mechanisms that control their formation are important to the development of new successful strategies for the treatment of patients with spinal cord injuries. Here we discuss the anatomical, physiological and behavioral changes that take place in response to injury-induced plasticity after damage to the dorsal column pathway in rats and monkeys. Complete section of the dorsal columns of the spinal cord at a high cervical level in monkeys and rats interrupts the ascending axon branches of low threshold mechanoreceptor afferents subserving the forelimb and the rest of the lower body. Such lesions render the corresponding part of the somatotopic representation of primary somatosensory cortex totally unresponsive to tactile stimuli. There are also behavioral consequences of the sensory loss, including an impaired use of the hand/forelimb in manipulating small objects. In monkeys, if some of the afferents from the hand remain intact after dorsal column lesions, these remaining afferents extensively reactivate portions of somatosensory cortex formerly representing the hand. This functional reorganization develops over a postoperative period of one month, during which hand use rapidly improves. These recoveries appear to be mediated, at least in part, by the sprouting of preserved afferents within the cuneate nucleus of the dorsal column-trigeminal complex. In rats, such functional collateral sprouting has been promoted by the post-lesion digestion of the perineuronal net in the cuneate nucleus. Thus, this and other

  12. Study on the Mechanism Underlying the Regulation of the NMDA Receptor Pathway in Spinal Dorsal Horns of Visceral Hypersensitivity Rats by Moxibustion

    PubMed Central

    Wang, L. D.; Zhao, J. M.; Huang, R. J.; Tan, L. Y.; Hu, Z. H.; Weng, Z. J.; Wang, K.; Wu, H. G.; Liu, H. R.

    2016-01-01

    Visceral hypersensitivity is enhanced in irritable bowel syndrome (IBS) patients. Treatment of IBS visceral pain by moxibustion methods has a long history and rich clinical experience. In the clinic, moxibustion on the Tianshu (ST25) and Shangjuxu (ST37) acupoints can effectively treat bowel disease with visceral pain and diarrhea symptoms. To investigate the regulatory function of moxibustion on the Tianshu (ST25) and Shangjuxu (ST37) acupoints on spinal cord NR1, NR2B, and PKCε protein and mRNA expression in irritable bowel syndrome (IBS) visceral hypersensitivity rats, we did some research. In the study, we found that moxibustion effectively relieved the IBS visceral hyperalgesia status of rats. Analgesic effect of moxibustion was similar to intrathecal injection of Ro 25-6981. The expression of NR1, NR2B, and PKCε in the spinal dorsal horns of IBS visceral hyperalgesia rats increased. Moxibustion on the Tianshu and Shangjuxu acupoints might inhibit the visceral hypersensitivity, simultaneously decreasing the expression of NR1, NR2B, and PKCε in spinal cord of IBS visceral hyperalgesia rats. Based on the above experimental results, we hypothesized NR1, NR2B, and PKCε of spinal cord could play an important role in moxibustion inhibiting the process of central sensitization and visceral hyperalgesia state. PMID:27200098

  13. Neuronal and glial expression of inward rectifier potassium channel subunits Kir2.x in rat dorsal root ganglion and spinal cord.

    PubMed

    Murata, Yuzo; Yasaka, Toshiharu; Takano, Makoto; Ishihara, Keiko

    2016-03-23

    Inward rectifier K(+) channels of the Kir2.x subfamily play important roles in controlling the neuronal excitability. Although their cellular localization in the brain has been extensively studied, only a few studies have examined their expression in the spinal cord and peripheral nervous system. In this study, immunohistochemical analyses of Kir2.1, Kir2.2, and Kir2.3 expression were performed in rat dorsal root ganglion (DRG) and spinal cord using bright-field and confocal microscopy. In DRG, most ganglionic neurons expressed Kir2.1, Kir2.2 and Kir2.3, whereas satellite glial cells chiefly expressed Kir2.3. In the spinal cord, Kir2.1, Kir2.2 and Kir2.3 were all expressed highly in the gray matter of dorsal and ventral horns and moderately in the white matter also. Within the gray matter, the expression was especially high in the substantia gelatinosa (lamina II). Confocal images obtained using markers for neuronal cells, NeuN, and astrocytes, Sox9, showed expression of all three Kir2 subunits in both neuronal somata and astrocytes in lamina I-III of the dorsal horn and the lateral spinal nucleus of the dorsolateral funiculus. Immunoreactive signals other than those in neuronal and glial somata were abundant in lamina I and II, which probably located mainly in nerve fibers or nerve terminals. Colocalization of Kir2.1 and 2.3 and that of Kir2.2 and 2.3 were present in neuronal and glial somata. In the ventral horn, motor neurons and interneurons were also immunoreactive with the three Kir2 subunits. Our study suggests that Kir2 channels composed of Kir2.1-2.3 subunits are expressed in neuronal and glial cells in the DRG and spinal cord, contributing to sensory transduction and motor control. PMID:26854211

  14. Structural and molecular alterations of primary afferent fibres in the spinal dorsal horn in vincristine-induced neuropathy in rat.

    PubMed

    Thibault, Karine; Rivals, Isabelle; M'Dahoma, Saïd; Dubacq, Sophie; Pezet, Sophie; Calvino, Bernard

    2013-11-01

    Vincristine is one of the most common anti-cancer drug therapies administered for the treatment of many types of cancer. Its dose-limiting side effect is the emergence of peripheral neuropathy, resulting in chronic neuropathic pain in many patients. This study sought to understand the mechanisms underlying the development of neuropathic pain by vincristine-induced neurotoxicity. We focused on signs of functional changes and revealed that deep layers of the spinal cord (III-IV) experience increased neuronal activity both in the absence of peripheral stimulation and, as a result of tactile mechanical stimulations. These laminae and superficial laminae I-II were also subject to structural changes as evidenced by an increase in immunoreactivity of Piccolo, a marker of active presynaptic elements. Further investigations performed, using DNA microarray technology, describe a large number of genes differentially expressed in dorsal root ganglions and in the spinal dorsal horn after vincristine treatment. Our study describes an important list of genes differentially regulated by vincristine treatment that will be useful for future studies and brings forward evidence for molecular and anatomical modifications of large diameter sensory neurons terminating in deep dorsal horn laminae, which could participate in the development of tactile allodynia. PMID:23975629

  15. Radiotherapy Suppresses Bone Cancer Pain through Inhibiting Activation of cAMP Signaling in Rat Dorsal Root Ganglion and Spinal Cord

    PubMed Central

    Zhu, Guiqin; Dong, Yanbin; He, Xueming; Zhao, Ping; Yang, Aixing; Zhou, Rubing; Ma, Jianhua; Xie, Zhong; Song, Xue-Jun

    2016-01-01

    Radiotherapy is one of the major clinical approaches for treatment of bone cancer pain. Activation of cAMP-PKA signaling pathway plays important roles in bone cancer pain. Here, we examined the effects of radiotherapy on bone cancer pain and accompanying abnormal activation of cAMP-PKA signaling. Female Sprague-Dawley rats were used and received tumor cell implantation (TCI) in rat tibia (TCI cancer pain model). Some of the rats that previously received TCI treatment were treated with X-ray radiation (radiotherapy). Thermal hyperalgesia and mechanical allodynia were measured and used for evaluating level of pain caused by TCI treatment. PKA mRNA expression in dorsal root ganglion (DRG) was detected by RT-PCR. Concentrations of cAMP, IL-1β, and TNF-α as well as PKA activity in DRG and the spinal cord were measured by ELISA. The results showed that radiotherapy significantly suppressed TCI-induced thermal hyperalgesia and mechanical allodynia. The level of PKA mRNA in DRG, cAMP concentration and PKA activity in DRG and in the spinal cord, and concentrations of IL-1β and TNF-α in the spinal cord were significantly reduced by radiotherapy. In addition, radiotherapy also reduced TCI-induced bone loss. These findings suggest that radiotherapy may suppress bone cancer pain through inhibition of activation of cAMP-PKA signaling pathway in DRG and the spinal cord. PMID:26989332

  16. Opiate receptor agonists regulate phosphorylation of synapsin I in cocultures of rat spinal cord and dorsal root ganglion.

    PubMed Central

    Nah, S Y; Saya, D; Barg, J; Vogel, Z

    1993-01-01

    Kappa opiate receptor agonists applied to cocultures of spinal cord and dorsal root ganglion neurons have been previously shown to inhibit voltage-dependent Ca2+ influx and adenylate cyclase activity. Here we describe the effect of kappa opiate receptor agonists on phosphorylation of synapsin I, a synaptic-vesicle-associated protein whose phosphorylation was shown to be regulated by cAMP and Ca2+ concentrations. Depolarization of spinal cord-dorsal root ganglion cocultured cells (by high K+ or veratridine) and the addition of forskolin (which activates adenylate cyclase) led to increased phosphorylation of synapsin I. Addition of kappa opiate agonists attenuated both the depolarization- and the forskolin-induced phosphorylation of synapsin I. This attenuation was blocked by the opiate antagonist naloxone. mu and delta opiate receptor agonists had much weaker effects on the depolarization-induced phosphorylation of synapsin I. Similarly, kappa opiate agonists decreased (by 40-60%) the high-K+- or veratridine-induced phosphorylation of synapsin I in spinal cord synaptosomes. These results show that opiate ligands modulate synapsin I phosphorylation. Moreover, the data could explain the reduction in synaptic efficacy observed after opiate treatment. Images Fig. 1 Fig. 2 Fig. 3 Fig. 5 Fig. 7 PMID:8097883

  17. Upregulation of Chemokine CXCL12 in the Dorsal Root Ganglia and Spinal Cord Contributes to the Development and Maintenance of Neuropathic Pain Following Spared Nerve Injury in Rats.

    PubMed

    Bai, Liying; Wang, Xinru; Li, Zhisong; Kong, Cunlong; Zhao, Yonghui; Qian, Jun-Liang; Kan, Quancheng; Zhang, Wei; Xu, Ji-Tian

    2016-02-01

    Emerging evidence indicates that CXCL12/CXCR4 signaling is involved in chronic pain. However, few studies have systemically assessed its role in direct nerve injury-induced neuropathic pain and the underlying mechanism. Here, we determined that spared nerve injury (SNI) increased the expression of CXCL12 and its cognate receptor CXCR4 in lumbar 5 dorsal root ganglia (DRG) neurons and satellite glial cells. SNI also induced long-lasting upregulation of CXCL12 and CXCR4 in the ipsilateral L4-5 spinal cord dorsal horn, characterized by CXCL12 expression in neurons and microglia, and CXCR4 expression in neurons and astrocytes. Moreover, SNI-induced a sustained increase in TNF-α expression in the DRG and spinal cord. Intraperitoneal injection (i.p.) of the TNF-α synthesis inhibitor thalidomide reduced the SNI-induced mechanical hypersensitivity and inhibited the expression of CXCL12 in the DRG and spinal cord. Intrathecal injection (i.t.) of the CXCR4 antagonist AMD3100, both 30 min before and 7 days after SNI, reduced the behavioral signs of allodynia. Rats given an i.t. or i.p. bolus of AMD3100 on day 8 of SNI exhibited attenuated abnormal pain behaviors. The neuropathic pain established following SNI was also impaired by i.t. administration of a CXCL12-neutralizing antibody. Moreover, repetitive i.t. AMD3100 administration prevented the activation of ERK in the spinal cord. The mechanical hypersensitivity induced in naïve rats by i.t. CXCL12 was alleviated by pretreatment with the MEK inhibitor PD98059. Collectively, our results revealed that TNF-α might mediate the upregulation of CXCL12 in the DRG and spinal cord following SNI, and that CXCL12/CXCR4 signaling via ERK activation contributes to the development and maintenance of neuropathic pain. PMID:26781879

  18. Localization of the NBMPR-sensitive equilibrative nucleoside transporter, ENT1, in the rat dorsal root ganglion and lumbar spinal cord.

    PubMed

    Governo, Ricardo J M; Deuchars, Jim; Baldwin, Stephen A; King, Anne E

    2005-10-19

    ENT1 is an equilibrative nucleoside transporter that enables trans-membrane bi-directional diffusion of biologically active purines such as adenosine. In spinal cord dorsal horn and in sensory afferent neurons, adenosine acts as a neuromodulator with complex pro- and anti-nociceptive actions. Although uptake and release mechanisms for adenosine are believed to exist in both the dorsal horn and sensory afferent neurons, the expression profile of specific nucleoside transporter subtypes such as ENT1 is not established. In this study, immunoblot analysis with specific ENT1 antibodies (anti-rENT1(227-290) or anti-hENT1(227-290)) was used to reveal the expression of ENT1 protein in tissue homogenates of either adult rat dorsal horn or dorsal root ganglia (DRG). Immunoperoxidase labeling with ENT1 antibodies produced specific staining in dorsal horn which was concentrated over superficial laminae, especially the substantia gelatinosa (lamina II). Immunofluorescence double-labeling revealed a punctate pattern for ENT1 closely associated, in some instances, with cell bodies of either neurons (confirmed with NeuN) or glia (confirmed with CNPase). Electron microscopy analysis of ENT1 expression in lamina II indicated its presence within pre- and post-synaptic elements, although a number of other structures, including myelinated and unmyelinated, axons were also labeled. In sensory ganglia, ENT1 was localized to a high proportion of cell bodies of all sizes that co-expressed substance P, IB4 or NF, although ENT1 was most highly expressed in the peptidergic population. These data provide the first detailed account of the expression and cellular distribution of ENT1 in rat dorsal horn and sensory ganglia. The functional significance of ENT1 expression with regard to the homeostatic regulation of adenosine at synapses remains to be established. PMID:16226730

  19. Mechanical allodynia following contusion injury of the rat spinal cord is associated with loss of GABAergic inhibition in the dorsal horn.

    PubMed

    Drew, Geoffrey M; Siddall, Philip J; Duggan, Arthur W

    2004-06-01

    The present study investigated whether mechanical allodynia following contusive spinal cord injury (SCI) of the thoracic segments 12 and 13 of the rat was associated with a reduction in gamma-aminobutyric acid (GABA)ergic inhibition adjacent to the site of injury. Five to 7 days following SCI, extracellular recordings were obtained from dorsal horn neurones located 1-2 segments caudal to the injury, in non-allodynic and allodynic halothane anaesthetised rats and from comparable neurones in normal rats. To assess spinal GABAergic inhibition in the three groups of animals, spontaneous and evoked cell firing rates were recorded before, during and after microiontophoretic application of the GABA(A) receptor antagonist bicuculline. Administration of bicuculline to normal animals resulted in significant and reversible increases in the receptive field size, spontaneous firing rate, response to brushing and pinching the skin and afterdischarge activity of dorsal horn neurones, as well as decreasing paired-pulse depression of responses evoked by transcutaneous electrical stimulation. In non-allodynic SCI animals, bicuculline ejection led to significant changes in receptive field size, paired-pulse depression and responses to brush and pinch stimulation that were comparable to those observed in normal animals. By contrast, in allodynic SCI animals, bicuculline ejection had little or no effect on dorsal horn neurone responses to mechanical skin stimuli and paired-pulse depression despite reliably blocking the inhibition of cell firing produced by similarly applied GABA. The demonstration of reduced GABAergic inhibition predominantly in the allodynic SCI rats suggests that such a deficiency contributed to this pain-related behaviour acutely following SCI. PMID:15157699

  20. The role of c-AMP-dependent protein kinase in spinal cord and post synaptic dorsal column neurons in a rat model of visceral pain.

    PubMed

    Wu, Jing; Su, Guangxiao; Ma, Long; Zhang, Xuan; Lei, Yongzhong; Lin, Qing; Nauta, Haring J W; Li, Junfa; Fang, Li

    2007-04-01

    Visceral noxious stimulation induces central neuronal plasticity changes and suggests that the c-AMP-dependent protein kinase (PKA) signal transduction cascade contributes to long-term changes in nociceptive processing at the spinal cord level. Our previous studies reported the clinical neurosurgical interruption of post synaptic dorsal column neuron (PSDC) pathway by performing midline myelotomy effectively alleviating the intractable visceral pain in patients with severe pain. However, the intracellular cascade in PSDC neurons mediated by PKA nociceptive neurotransmission was not known. In this study, by using multiple experimental approaches, we investigated the role of PKA in nociceptive signaling in the spinal cord and PSDC neurons in a visceral pain model in rats with the intracolonic injection of mustard oil. We found that mustard oil injection elicited visceral pain that significantly changed exploratory behavior activity in rats in terms of decreased numbers of entries, traveled distance, active and rearing time, rearing activity and increased resting time when compared to that of rats receiving mineral oil injection. However, the intrathecal infusion of PKA inhibitor, H89 partially reversed the visceral pain-induced effects. Results from Western blot studies showed that mustard oil injection significantly induced the expression of PKA protein in the lumbosacral spinal cord. Immunofluorescent staining in pre-labeled PSDC neurons showed that mustard oil injection greatly induces the neuronal profile numbers. We also found that the intrathecal infusion of a PKA inhibitor, H89 significantly blocked the visceral pain-induced phosphorylation of c-AMP-responsive element binding (CREB) protein in spinal cord in rats. The results of our study suggest that the PKA signal transduction cascade may contribute to visceral nociceptive changes in spinal PSDC pathways. PMID:17320244

  1. Reactive oxygen species enhance excitatory synaptic transmission in rat spinal dorsal horn neurons by activating TRPA1 and TRPV1 channels.

    PubMed

    Nishio, N; Taniguchi, W; Sugimura, Y K; Takiguchi, N; Yamanaka, M; Kiyoyuki, Yasukuni; Yamada, H; Miyazaki, N; Yoshida, M; Nakatsuka, T

    2013-09-01

    Central neuropathic pain (CNP) in the spinal cord, such as chronic pain after spinal cord injury (SCI), is an incurable ailment. However, little is known about the spinal cord mechanisms underlying CNP. Recently, reactive oxygen species (ROS) have been recognized to play an important role in CNP of the spinal cord. However, it is unclear how ROS affect synaptic transmission in the dorsal horn of the spinal cord. To clarify how ROS impact on synaptic transmission, we investigated the effects of ROS on synaptic transmission in rat spinal cord substantia gelatinosa (SG) neurons using whole-cell patch-clamp recordings. Administration of tert-butyl hydroperoxide (t-BOOH), an ROS donor, into the spinal cord markedly increased the frequency and amplitude of spontaneous excitatory postsynaptic currents (sEPSCs) in SG neurons. This t-BOOH-induced enhancement was not suppressed by the Na(+) channel blocker tetrodotoxin. However, in the presence of a non-N-methyl-D-aspartate glutamate receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione, t-BOOH did not generate any sEPSCs. Furthermore, in the presence of a transient receptor potential ankyrin 1 (TRPA1) channel antagonist (HC-030031) or a transient receptor potential vanilloid 1 (TRPV1) channel antagonist (capsazepine or AMG9810), the t-BOOH-induced increase in the frequency of sEPSCs was inhibited. These results indicate that ROS enhance the spontaneous release of glutamate from presynaptic terminals onto SG neurons through TRPA1 and TRPV1 channel activation. Excessive activation of these ion channels by ROS may induce central sensitization in the spinal cord and result in chronic pain such as that following SCI. PMID:23707800

  2. Evidence for a haematogenous origin of some of the macrophages appearing in the spinal cord of the rat after dorsal rhizotomy.

    PubMed Central

    Ling, E A

    1979-01-01

    A single dose of colloidal carbon was given intravascularly to young adult rats in order to label circulating monocytes. Two days after injection dorsal rhizotomies were performed on the fifth to eighth cervical nerves on the right side. The rats were killed 1, 3, 4 and 8 days later. Electron microscopic examination of the spinal cord showed wide-spread tissue degeneration on the operated side in the dorsolateral fasciculus, the dorsal horn and the dorsal neuronal white column, the changes in the last named being the most severe. A variety of non-neuronal elements was found in the dorsolateral fasciculus and dorsal horn. These included astrocytes, oligodendrocytes, microglia-like cells, plasma cells, mast cells, polymorphonuclear leucocytes, monocytes and macrophages. Monocytes and macrophages were most common 3 and 4 days after operation. Some of these cells carried intracytoplasmic carbon particles. Carbon-labelled monocytes were observed in blood vessel lumina, perivascularly and in the neuropil. Monocytes crossing blood vessel walls were also encountered, indicating that the neuropil monocytes were derived from circulating cells. Macrophages were characterized by pleomorphic phagosomes which seemed to be composed largely of myelin remnants. The presence of carbon particles in their cytoplasm, and also their general similarity to monocytes, suggested that they originated from the latter. Local microglial cells were considered to be another source of macrophages. Indeed, there were present some microglia-like cells which were regarded as 'activated microglia' as they showed morphological resemblances to microglia on the one hand and to macrophages on the other. In particular their cytoplasm always included phagosomes. It is concluded that the macrophages which appear in the altered spinal cord following rhizotomy are derived both from circulating monocytes and from indigenous microglia. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10

  3. Clinically relevant concentration of pregabalin has no acute inhibitory effect on excitation of dorsal horn neurons under normal or neuropathic pain conditions: An intracellular calcium-imaging study in spinal cord slices from adult rats.

    PubMed

    Baba, Hiroshi; Petrenko, Andrey B; Fujiwara, Naoshi

    2016-10-01

    Pregabalin is thought to exert its therapeutic effect in neuropathic pain via binding to α2δ-1 subunits of voltage-gated calcium (Ca(2+)) channels. However, the exact analgesic mechanism after its binding to α2δ-1 subunits remains largely unknown. Whether a clinical concentration of pregabalin (≈10μM) can cause acute inhibition of dorsal horn neurons in the spinal cord is controversial. To address this issue, we undertook intracellular Ca(2+)-imaging studies using spinal cord slices with an intact attached L5 dorsal root, and examined if pregabalin acutely inhibits the primary afferent stimulation-evoked excitation of dorsal horn neurons in normal rats and in rats with streptozotocin-induced painful diabetic neuropathy. Under normal conditions, stimulation of a dorsal root evoked Ca(2+) signals predominantly in the superficial dorsal horn. Clinically relevant (10μM) and a very high concentration of pregabalin (100μM) did not affect the intensity or spread of dorsal root stimulation-evoked Ca(2+) signals, whereas an extremely high dose of pregabalin (300μM) slightly but significantly attenuated Ca(2+) signals in normal rats and in diabetic neuropathic (DN) rats. There was no difference between normal rats and DN rats with regard to the extent of signal attenuation at all concentrations tested. These results suggest that the activity of dorsal horn neurons in the spinal cord is not inhibited acutely by clinical doses of pregabalin under normal or DN conditions. It is very unlikely that an acute inhibitory action in the dorsal horn is the main analgesic mechanism of pregabalin in neuropathic pain states. PMID:27543338

  4. Expression and transport of Angiotensin II AT1 receptors in spinal cord, dorsal root ganglia and sciatic nerve of the rat

    PubMed Central

    Pavel, Jaroslav; Tang, Hui; Brimijoin, Stephen; Moughamian, Armen; Nishioku, Tsuyoshi; Benicky, Julius; Saavedra, Juan M

    2009-01-01

    To clarify the role of Angiotensin II in the regulation of peripheral sensory and motor systems, we initiated a study of the expression, localization and transport of Angiotensin II receptor types in the rat sciatic nerve pathway, including L4–L5 spinal cord segments, the corresponding dorsal root ganglia (DRGs) and the sciatic nerve. We used quantitative autoradiography for AT1 and AT2 receptors, and in situ hybridization to detect AT1A, AT1B and AT2 mRNAs. We found substantial expression and discrete localization of Angiotensin II AT1 receptors, with much higher numbers in the grey than in the white matter. A very high AT1 receptor expression was detected in the superficial dorsal horns and in neuronal clusters of the DRGs. Expression of AT1A mRNA was significantly higher than that of AT1B. AT1 receptor binding and AT1A and AT1B mRNAs were especially prominent in ventral horn motor neurons, and in the DRG neuronal cells. Unilateral dorsal rhizotomy significantly reduced AT1 receptor binding in the ipsilateral side of the superficial dorsal horn, indicating that a substantial number of dorsal horn AT1 receptors have their origin in the DRGs. After ligation of the sciatic nerve, there was a high accumulation of AT1 receptors proximal to the ligature, a demonstration of anterograde receptor transport. We found inconsistent levels of AT2 receptor binding and mRNA. Our results suggest multiple roles of Angiotensin II AT1 receptors in the regulation of sensory and motor functions. PMID:18976642

  5. Signalling of a step-like intensity change of noxious mechanical stimuli by dorsal horn neurones in the rat spinal cord.

    PubMed Central

    Laird, J M; Cervero, F

    1991-01-01

    1. Single-unit extracellular recordings were made from thirty-one dorsal horn neurones in the sacral spinal cord of barbiturate-anaesthetized rats. Each neurone was tested with four noxious mechanical pinches applied to its receptive field on the tail. Each pinch lasted 120 s, with a step-like change in intensity after 60 s. In two pinches the step increased the intensity, from 4 to 6 N or from 6 to 8 N, and in two the step decreased the intensity, from 8 to 6 N or from 6 to 4 N. 2. The ability of the neurones to signal these step changes in intensity was examined. Five neurones with an exclusively low-threshold afferent input (class 1) were tested, and found to fire only briefly at the start of the 120 s stimulus. Neurones with a high-threshold input (nociceptive neurones), either exclusively (class 3; n = 10) or in addition to a low-threshold input (class 2: n = 16), responded throughout the 120 s stimuli. 3. Nociceptive dorsal horn neurones have been divided into two groups of 'good' and 'poor' encoders on the basis of their response to the step changes in intensity. 4. 'Good' encoders (n = 13) were neurones signalling both a step increase and a step decrease in intensity, of which seven were class 2 and six class 3, five recorded in the superficial dorsal horn and eight in the deep dorsal horn. 5. 'Poor' encoders (n = 13) were neurones which failed to signal one or both of the step changes in intensity, of which nine were class 2 and four class 3, three recorded in the superficial dorsal horn and ten in the deep dorsal horn. 6. These results demonstrate that neurones with similar input properties and location are not necessarily a homogeneous group in terms of their processing of nociceptive stimuli. Moreover, they suggest that subgroups of both class 2 and class 3 and of superficial and deep dorsal horn neurones contribute to the different components of a nociceptive response. 7. We propose that the output and projection target of a particular dorsal horn

  6. Neuropathological and neuroprotective features of vitamin B12 on the dorsal spinal ganglion of rats after the experimental crush of sciatic nerve: an experimental study

    PubMed Central

    2013-01-01

    Background Spinal motoneuron neuroprotection by vitaminB12 was previously reported; the present study was carried out to evaluate neuroprotectivity in the dorsal root ganglion sensory neuron. Methods In present study thirty-six Wister-Albino rats (aged 8–9 weeks and weighing 200–250 g) were tested. The animals were randomly divided into 6 groups which every group contained 6 rats. Group A: received normal saline (for 42 days); Group B: vitamin B12 was administered (0.5 mg/kg/day for 21 days); Group C: received vitamin B12 (1 mg/kg/day for 21days); Group D: received vitamin B12 (0.5 mg/kg/day for 42 days); Group E; received vitamin B12 (1 mg/kg/day for 42 days); Group F; received no treatment. The L5 Dorsal Root Ganglion (DRG) neurons count compared to the number of left and right neurons .Furthermore, DRG sensory neurons for regeneration were evaluated 21 or 42 days after injury (each group was analyzed by One-Way ANOVA test). Results (1): The comparison of left crushed neurons (LCN) number with right non-crushed neurons in all experimental groups (B, C, D and C), indicating a significant decline in their neurons enumeration (p<0/05). (2): The comparison of test group’s LCN with the control group’s LCN revealed a significant rise in the number of experimental group neurons (p<0/05). (3): Moreover, comparing the number of right neurons in experimental groups with the number of neurons in crushed neurons indicated that the average number of right neurons showed a significant increase in experimental groups (p<0/05). Conclusion Consequently, the probability of nerve regeneration will be increased by the increment of the administered drug dosage and duration. On the other hand, the regeneration and healing in Dorsal Spinal Ganglion will be improved by increase of administration time and vitamin B12 dose, indicating that such vitamin was able to progress recovery process of peripheral nerves damage in experimental rats. Finally, our results have important

  7. L5 spinal nerve axotomy induces sensitization of cutaneous L4 Aβ-nociceptive dorsal root ganglion neurons in the rat in vivo.

    PubMed

    Djouhri, Laiche

    2016-06-15

    Partial nerve injury often leads to peripheral neuropathic pain (PNP), a major health problem that lacks effective drug treatment. PNP is characterized by ongoing/spontaneous pain, and hypersensitivity to noxious (hyperalgesia) and innocuous (allodynia) stimuli. Preclinical studies using the L5 spinal nerve ligation/axotomy (SNL/SNA) model of PNP suggest that this type of chronic pain results partly from sensitization of ipsilateral L4C-and Aδ-fiber nociceptive dorsal root ganglion (DRG) neurons, but whether L4 β-nociceptors, which constitute a substantial group of DRG neurons, also become sensitized remains unanswered. To address this issue, intracellular recordings from somata of cutaneous Aβ-nociceptors (classified according to their dorsal root conduction velocities (>6.5m/s), and physiologically based on their responses to noxious (but not innocuous) mechanical stimuli) were made from L4-DRGs in normal (control) rats and in rats seven days after L5 SNA in vivo. Compared with control, cutaneous L4 Aβ-nociceptive DRG neurons in SNA rats (that developed mechanical hypersensitivity) exhibited sensitization indicated by: a) decreased mean mechanical threshold (from 57.8±7.1 to 10.3±1.7mN), b) decreased mean dorsal root electrical threshold (from 11.4±0.7 to 4.3±0.4V), c) increased mean response to a suprathreshold mechanical stimulus (from 18.5±1.8 to 34±3.7spikes/sec) and d) an obvious, but non-significant, increase in the incidence of ongoing/spontaneous activity (from 3% to 18%). These findings suggest that cutaneous L4 Aβ-nociceptors also become sensitized after L5 SNA, and that sensitization of this subclass of A-fiber nociceptors may contribute both directly and indirectly to nerve injury-induced PNP. PMID:27173166

  8. Activation of the cAMP-PKA signaling pathway in rat dorsal root ganglion and spinal cord contributes toward induction and maintenance of bone cancer pain.

    PubMed

    Zhu, Gui-Qin; Liu, Su; He, Duan-Duan; Liu, Yue-Peng; Song, Xue-Jun

    2014-08-01

    The objective of this study was to explore the role of cyclic adenosine monophosphate-protein kinase A (cAMP-PKA) signaling in the development of bone cancer pain in rats. Female Sprague-Dawley rats (N=48) were divided randomly into four groups: sham (n=8), tumor cell implantation (TCI) (n=16), TCI+saline (n=8), and TCI+PKA inhibitor (n=16). Bone cancer-induced pain behaviors - thermal hyperalgesia and mechanical allodynia - were tested at postoperative days -3, -1, 1, 3, 5, 7, 10, and 14. A PKA inhibitor, Rp-cAMPS (1 mmol/l/20 μl), was injected intrathecally on postoperative days 3, 4, and 5 (early phase) or 7, 8, and 9 postoperative days (late phase). The expression of PKA mRNA in dorsal root ganglia (DRG) was detected by reverse transcription-PCR. The concentration of cAMP and activity of PKA in DRG and spinal cord were measured by enzyme-linked immunosorbent assay. TCI treatment induced significant pain behaviors, manifested as thermal hyperalgesia and mechanical allodynia. Spinal administration of the PKA inhibitor Rp-cAMPS during the early phase and late phase significantly delayed or reversed, respectively, TCI-induced thermal hyperalgesia and mechanical allodynia. TCI treatment also led to obvious tumor growth and bone destruction. The level of PKA mRNA in the DRG, as well as the concentration of cAMP and the activity of PKA, in both the DRG and spinal cord were significantly increased after TCI treatment (P<0.01). We conclude that the inhibition of the cAMP-PKA signaling pathway may reduce bone cancer pain. PMID:24978483

  9. Increased expression of HCN2 channel protein in L4 dorsal root ganglion neurons following axotomy of L5- and inflammation of L4-spinal nerves in rats.

    PubMed

    Smith, T; Al Otaibi, M; Sathish, J; Djouhri, L

    2015-06-01

    A hallmark of peripheral neuropathic pain (PNP) is chronic spontaneous pain and/or hypersensitivity to normally painful stimuli (hyperalgesia) or normally nonpainful stimuli (allodynia).This pain results partly from abnormal hyperexcitability of dorsal root ganglion (DRG) neurons. We have previously shown, using a modified version of the lumbar 5 (L5)-spinal nerve ligation model of PNP (mSNA model involving L5-spinal nerve axotomy plus loose ligation of the lumbar 4 (L4)-spinal nerve with neuroinflammation-inducing chromic-gut), that L4 DRG neurons exhibit increased spontaneous activity, the key characteristic of neuronal hyperexcitability. The underlying ionic and molecular mechanisms of the hyperexcitability of L4 DRG neurons are incompletely understood, but could result from changes in expression and/or function of ion channels including hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which are active near the neuron's resting membrane potential, and which produce an excitatory inward current that depolarizes the membrane potential toward the threshold of action potential generation. Therefore, in the present study we used the mSNA model to investigate whether: (a) expression of HCN1-HCN3 channels is altered in L4 DRG neurons which, in the mSNA model, are essential for transmission of the evoked pain, and which contribute to chronic spontaneous pain, and (b) local (intraplantar) blockade of these HCN channels, with a specific blocker, ZD7288, attenuates chronic spontaneous pain and/or evoked pain in mSNA rats. We found 7days after mSNA: (1) a significant increase in HCN2-immunoreactivity in small (<30μm) DRG neurons (predominantly IB4-negative neurons), and in the proportion of small neurons expressing HCN2 (putative nociceptors); (2) no significant change in HCN1- or HCN3-immunoreactivity in all cell types; and (3) attenuation, with ZD7288 (100μM intraplantar), of chronic spontaneous pain behavior (spontaneous foot lifting) and mechanical

  10. Sensitization of the transient receptor potential vanilloid type 1 ion channel by isoflurane or sevoflurane does not result in extracellular signal-regulated kinase 1/2 activation in rat spinal dorsal horn neurons.

    PubMed

    White, J P M; Cibelli, M; Fidalgo, A R; Paule, C C; Anderson, P J; Jenes, A; Rice, A S C; Nagy, I

    2010-03-17

    Clinically relevant concentrations of isoflurane or sevoflurane sensitize transient receptor potential vanilloid type 1 to several of its activators, including capsaicin. It has, moreover, been suggested these volatile general anaesthetics may augment nociceptive signalling arising from surgical procedures and thereby contribute to post-operative pain. To investigate this suggestion, we have studied intraplantar capsaicin injection-induced phosphorylation of extracellular signal-regulated kinase 1/2 in spinal dorsal horn neurons (which is a recognized marker of spinal nociceptive processing) in rat during isoflurane or sevoflurane anaesthesia after 60 min under anaesthesia. Control animals were anaesthetized with pentobarbital (which of itself does not activate extracellular signal-regulated kinase 1/2 in spinal dorsal horn neurons). Unilateral intraplantar capsaicin injection in control animals evoked extracellular signal-regulated kinase 1/2 phosphorylation in a group of neurons in lamina I and lamina II of the ipsilateral spinal dorsal horn in a somatotopically appropriate area. In contrast, both anaesthetic gases (given for 60 min and without subsequent capsaicin injection) induced extracellular signal-regulated kinase 1/2 activation in a different group of mainly lamina I neurons bilaterally. The total number of spinal dorsal horn neurons labelled on the ipliateral side following capsaicin injection into the isoflurane-, or sevoflurane-, anaesthetized animals was significantly less than that produced by capsaicin alone. Further, capsaicin injection into isoflurane-, or sevoflurane-, anaesthetized animals reduced extracellular signal-regulated kinase 1/2 phosphorylation induced by the gases alone on both sides. These findings do not support the suggestion that isoflurane-, or sevoflurane-, induced sensitization of transient receptor potential vanilloid type 1 by capsaicin, or other agonist, is translated into induction of spinal nociceptive processing and

  11. Below Level Central Pain Induced by Discrete Dorsal Spinal Cord Injury

    PubMed Central

    Ellis, Amanda L.; McFadden, Andrew; Brown, Kimberley; Starnes, Charlotte; Maier, Steven F.; Watkins, Linda R.; Falci, Scott

    2010-01-01

    Abstract Central neuropathic pain occurs with multiple sclerosis, stroke, and spinal cord injury (SCI). Models of SCI are commonly used to study central neuropathic pain and are excellent at modeling gross physiological changes. Our goal was to develop a rat model of central neuropathic pain by traumatizing a discrete region of the dorsal spinal cord, thereby avoiding issues including paralysis, urinary tract infection, and autotomy. To this end, dorsal root avulsion was pursued. The model was developed by first determining the number of avulsed dorsal roots sufficient to induce below-level hindpaw mechanical allodynia. This was optimally achieved by unilateral T13 and L1 avulsion, which resulted in tissue damage confined to Lissauer's tract, dorsal horn, and dorsal columns, at the site of avulsion, with no gross physical changes at other spinal levels. Behavior following avulsion was compared to that following rhizotomy of the T13 and L1 dorsal roots, a commonly used model of neuropathic pain. Avulsion induced below-level allodynia that was more robust and enduring than that seen after rhizotomy. This, plus the lack of direct spinal cord damage associated with rhizotomy, suggests that avulsion is not synonymous with rhizotomy, and that avulsion (but not rhizotomy) is a model of central neuropathic pain. The new model described here is the first to use discrete dorsal horn damage by dorsal root avulsion to create below-level bilateral central neuropathic pain. PMID:20649467

  12. Injury-specific functional alteration of N-type voltage-gated calcium channels in synaptic transmission of primary afferent C-fibers in the rat spinal superficial dorsal horn.

    PubMed

    Takasu, Keiko; Ogawa, Koichi; Minami, Kazuhisa; Shinohara, Shunji; Kato, Akira

    2016-02-01

    We investigated functional alterations of voltage-gated calcium channels (VGCCs) in excitatory synaptic transmission from primary afferent A- and C-fibers after peripheral nerve injury. Patch-clamp recordings were performed on substantia gelatinosa (SG) neurons of spinal cord slices with an attached dorsal root, prepared from L5 spinal nerve-ligated (SNL) rats. The effects of neuronal VGCC blockers, ω-conotoxin GVIA (ω-CgTX) for N-type channels and ω-agatoxin IVA (ω-AgaIVA) for P/Q-type channels, on evoked excitatory postsynaptic currents (eEPSCs) by stimulation of A- or C-fibers were studied. Besides, electrophysiological assay using dorsal root ganglion (DRG) and immunohistochemistry were done. In naïve rats, ω-CgTX (0.1-1μM) reduced more effectively A-fiber eEPSCs than C-fiber ones. After nerve injury, ω-CgTX produced great inhibition of C-fiber eEPSCs in slices with the injured L5 dorsal root of SNL model rats, as compared to sham-operated rats. By contrast, in slices with the non-injured L4 one, inhibitory effects of ω-CgTX were not changed. This occurred concurrently with increased expression of N-type VGCCs in L5 spinal dorsal horn and with enhanced Ca(2+) currents through N-type VGCCs in small-sized (C-type) L5 DRG. In terms of A-fiber eEPSCs, ω-CgTX elicited similar inhibition in nerve-injured and sham-operated rats. ω-AgaIVA (0.1μM) had less effect on A- or C-fiber eEPSCs. These results indicate that N-type, but not P/Q-type, VGCCs mainly contribute to excitatory synaptic transmission from A- and C-fibers in the spinal dorsal horn. More importantly, following nerve injury, the functional contribution of N-type VGCCs to nociceptive transmission is increased in the pre-synaptic terminals of injured C-fibers. PMID:26708163

  13. Developmentally Regulated Expression of HDNF/NT-3 mRNA in Rat Spinal Cord Motoneurons and Expression of BDNF mRNA in Embryonic Dorsal Root Ganglion.

    PubMed

    Ernfors, Patrik; Persson, Håkan

    1991-01-01

    Northern blot analysis was used to demonstrate high levels of hippocampus-derived neurotrophic factor/neurotrophin-3 (HDNF/NT-3) mRNA in the embryonic day (E) 13 - 14 and 15 - 16 spinal cord. The level decreased at E18 - 19 and remained the same until postnatal day (P) 1, after which it decreased further to a level below the detection limit in the adult. In situ hybridization revealed that the NT-3 mRNA detected in the developing spinal cord was derived from motoneurons and the decrease seen at E18 - 19 was caused by a reduction in the number of motoneurons expressing NT-3 mRNA. The distribution of NT-3 mRNA-expressing cells in the E15 spinal cord was very similar to the distribution of cells expressing choline acetyltransferase or nerve growth factor receptor (NGFR) mRNA. Moreover, a striking similarity between the developmentally regulated expression of NT-3 and NGFR mRNA was noted in spinal cord motoneurons. A subpopulation of all neurons in the dorsal root ganglia expressed brain-derived neurotrophic factor (BDNF) mRNA from E13, the earliest time examined, to adulthood. These results are consistent with a trophic role of NT-3 for proprioceptive sensory neurons innervating the ventral horn, and imply a local action of BDNF for developing sensory neurons within the dorsal root ganglia. PMID:12106253

  14. Hypericum perforatum Attenuates Spinal Cord Injury-Induced Oxidative Stress and Apoptosis in the Dorsal Root Ganglion of Rats: Involvement of TRPM2 and TRPV1 Channels.

    PubMed

    Özdemir, Ümit Sinan; Nazıroğlu, Mustafa; Şenol, Nilgün; Ghazizadeh, Vahid

    2016-08-01

    Oxidative stress and cytosolic Ca(2+) overload have important roles on apoptosis in dorsal root ganglion (DRG) neurons after spinal cord injury (SCI). Hypericum perforatum (HP) has an antioxidant property in the DRGs due to its ability to modulate NADPH oxidase and protein kinase C pathways. We aimed to investigate the protective property of HP on oxidative stress, apoptosis, and Ca(2+) entry through transient receptor potential melastatin 2 (TRPM2) and transient receptor potential vanilloid 1 (TRPV1) channels in SCI-induced DRG neurons of rats. Rats were divided into four groups as control, HP, SCI, and SCI + HP. The HP groups received 30 mg/kg HP for three concessive days after SCI induction. The SCI-induced TRPM2 and TRPV1 currents and cytosolic free Ca(2+) concentration were reduced by HP. The SCI-induced decrease in glutathione peroxidase and cell viability values were ameliorated by HP treatment, and the SCI-induced increase in apoptosis, caspase 3, caspase 9, cytosolic reactive oxygen species (ROS) production, and mitochondrial membrane depolarization values in DRG of SCI group were overcome by HP treatment. In conclusion, we observed a protective role of HP on SCI-induced oxidative stress, apoptosis, and Ca(2+) entry through TRPM2 and TRPV1 in the DRG neurons. Our findings may be relevant to the etiology and treatment of SCI by HP. Graphical Abstract Possible molecular pathways of involvement of Hypericum perforatum (HP) on apoptosis, oxidative stress, and calcium accumulation through TRPM2 and TRPV1 channels in DRG neurons of SCI-induced rats. The TRPM2 channel is activated by ADP-ribose and oxidative stress through activation of ADP-ribose pyrophosphate although it was inhibited by N-(p-amylcinnamoyl) anthranilic acid (ACA) and 2-aminoethyl diphenylborinate (2APB). The TRPV1 channel is activated by oxidative stress and capsaicin and it is blocked by capsazepine. Injury in the DRG can result in augmented ROS release, leading to Ca(2+) uptake through

  15. Expression of LC3 and Beclin 1 in the spinal dorsal horn following spinal nerve ligation-induced neuropathic pain.

    PubMed

    Zhang, Enji; Yi, Min-Hee; Ko, Youngkwon; Kim, Hyun-Woo; Seo, Je Hoon; Lee, Young Ho; Lee, Wonhyung; Kim, Dong Woon

    2013-06-26

    Impaired spinal GABAergic inhibitory function is known to be pivotal in neuropathic pain (NPP). At present, data concerning time-dependent alterations in cell type and cell death in the spinal dorsal horn are highly controversial, likely related to the experimental NPP model used. In this study, we examined the expression of autophagy using a L5 spinal nerve ligation (SNL)-induced neuropathic pain rat model. Following ligation of the spinal nerve, neuropathic pain behavior, such as mechanical allodynia, was induced rapidly and maintained for 14 days. After testing for mechanical allodynia, we assessed the changes in expression of LC3 and Beclin 1 in the spinal cord following SNL. Immunohistochemical analysis showed that the levels of LC3 and Beclin 1 protein in the ipsilateral L5 spinal dorsal horn were significantly elevated on day 14 following SNL. Double immunohistochemical analysis further confirmed increases in LC3 and Beclin 1 in mostly neurons and a few astrocytes following SNL. LC3 and Beclin 1 expressions were upregulated in GABAergic interneurons of spinal dorsal horn after SNL, while the loss of GABAergic interneurons did not change significantly. Our results suggest that autophagic disruption in GABAergic interneurons and astrocytes following peripheral nerve injury might be involved in the induction and maintenance of neuropathic pain. PMID:23665054

  16. Bulleyaconitine A depresses neuropathic pain and potentiation at C-fiber synapses in spinal dorsal horn induced by paclitaxel in rats.

    PubMed

    Zhu, He-Quan; Xu, Jing; Shen, Kai-Feng; Pang, Rui-Ping; Wei, Xu-Hong; Liu, Xian-Guo

    2015-11-01

    Paclitaxel, a widely used chemotherapeutic agent, often induces painful peripheral neuropathy and at present no effective drug is available for treatment of the serious side effect. Here, we tested if intragastrical application of bulleyaconitine A (BLA), which has been approved for clinical treatment of chronic pain in China since 1985, could relieve the paclitaxel-induced neuropathic pain. A single dose of BLA attenuated the mechanical allodynia, thermal hyperalgesia induced by paclitaxel dose-dependently. Repetitive administration of the drug (0.4 and 0.8 mg/kg, t.i.d. for 7 d) during or after paclitaxel treatment produced a long-lasting inhibitory effect on thermal hyperalgesia, but not on mechanical allodynia. In consistency with the behavioral results, in vivo electrophysiological experiments revealed that spinal synaptic transmission mediated by C-fiber but not A fiber was potentiated, and the magnitude of long-term potentiation (LTP) at C-fiber synapses induced by the same high frequency stimulation was ~50% higher in paclitaxel-treated rats, compared to the naïve rats. Spinal or intravenous application of BLA depressed the spinal LTP, dose-dependently. Furthermore, patch clamp recordings in spinal cord slices revealed that the frequency but not amplitude of both spontaneous excitatory postsynaptic current (sEPSCs) and miniature excitatory postsynaptic currents (mEPSCs) in lamina II neurons was increased in paclitaxel-treated rats, and the superfusion of BLA reduced the frequency of sEPSCs and mEPSCs in paclitaxel-treated rats but not in naïve ones. Taken together, we provide novel evidence that BLA attenuates paclitaxel-induced neuropathic pain and that depression of spinal LTP at C-fiber synapses via inhibiting presynaptic transmitter release may contribute to the effect. PMID:26376216

  17. Glial glutamate transporter and glutamine synthetase regulate GABAergic synaptic strength in the spinal dorsal horn.

    PubMed

    Jiang, Enshe; Yan, Xisheng; Weng, Han-Rong

    2012-05-01

    Decreased GABAergic synaptic strength ('disinhibition') in the spinal dorsal horn is a crucial mechanism contributing to the development and maintenance of pathological pain. However, mechanisms leading to disinhibition in the spinal dorsal horn remain elusive. We investigated the role of glial glutamate transporters (GLT-1 and GLAST) and glutamine synthetase in maintaining GABAergic synaptic activity in the spinal dorsal horn. Electrically evoked GABAergic inhibitory post-synaptic currents (eIPSCs), spontaneous IPSCs (sIPSCs) and miniature IPSCs were recorded in superficial spinal dorsal horn neurons of spinal slices from young adult rats. We used (2S,3S)-3-[3-[4-(trifluoromethyl)benzoylamino]benzyloxy]aspartate (TFB-TBOA), to block both GLT-1 and GLAST and dihydrokainic acid to block only GLT-1. We found that blockade of both GLAST and GLT-1 and blockade of only GLT-1 in the spinal dorsal horn decreased the amplitude of GABAergic eIPSCs, as well as both the amplitude and frequency of GABAergic sIPSCs or miniature IPSCs. Pharmacological inhibition of glial glutamine synthetase had similar effects on both GABAergic eIPSCs and sIPSCs. We provided evidence demonstrating that the reduction in GABAergic strength induced by the inhibition of glial glutamate transporters is due to insufficient GABA synthesis through the glutamate-glutamine cycle between astrocytes and neurons. Thus, our results indicate that deficient glial glutamate transporters and glutamine synthetase significantly attenuate GABAergic synaptic strength in the spinal dorsal horn, which may be a crucial synaptic mechanism underlying glial-neuronal interactions caused by dysfunctional astrocytes in pathological pain conditions. PMID:22339645

  18. Chronic at-level thermal hyperalgesia following rat cervical contusion spinal cord injury is accompanied by neuronal and astrocyte activation and loss of the astrocyte glutamate transporter, GLT1, in superficial dorsal horn.

    PubMed

    Putatunda, Rajarshi; Hala, Tamara J; Chin, Jeannie; Lepore, Angelo C

    2014-09-18

    Neuropathic pain is a form of pathological nociception that occurs in a significant portion of traumatic spinal cord injury (SCI) patients, resulting in debilitating and often long-term physical and psychological burdens. While many peripheral and central mechanisms have been implicated in neuropathic pain, central sensitization of dorsal horn spinothalamic tract (STT) neurons is a major underlying substrate. Furthermore, dysregulation of extracellular glutamate homeostasis and chronic astrocyte activation play important underlying roles in persistent hyperexcitability of these superficial dorsal horn neurons. To date, central sensitization and astrocyte changes have not been characterized in cervical SCI-induced neuropathic pain models, despite the fact that a major portion of SCI patients suffer contusion trauma to cervical spinal cord. In this study, we have characterized 2 rat models of unilateral cervical contusion SCI that behaviorally result in chronic persistence of thermal hyperalgesia in the ipsilateral forepaw. In addition, we find that STT neurons are chronically activated in both models when compared to laminectomy-only uninjured rats. Finally, persistent astrocyte activation and significantly reduced expression of the major CNS glutamate transporter, GLT1, in superficial dorsal horn astrocytes are associated with both excitability changes in STT neurons and the neuropathic pain behavioral phenotype. In conclusion, we have characterized clinically-relevant rodent models of cervical contusion-induced neuropathic pain that result in chronic activation of both STT neurons and astrocytes, as well as compromise in astrocyte glutamate transporter expression. These models can be used as important tools to further study mechanisms underlying neuropathic pain post-SCI and to test potential therapeutic interventions. PMID:24833066

  19. Attenuated Glial K+ Clearance Contributes to Long-Term Synaptic Potentiation Via Depolarizing GABA in Dorsal Horn Neurons of Rat Spinal Cord

    PubMed Central

    Lee, Jaekwang; Favorov, Oleg V; Tommerdahl, Mark

    2014-01-01

    It has been reported that long-term enhancement of superficial dorsal horn (DHs) excitatory synaptic transmission underlies central sensitization, secondary hyperalgesia, and persistent pain. We tested whether impaired clearance of K+ and glutamate by glia in DHs may contribute to initiation and maintenance of the CNS pain circuit and sensorimotor abnormalities. Transient exposure of the spinal cord slice to fluorocitrate (FC) is shown to be accompanied by a protracted decrease of the DHs optical response to repetitive electrical stimulation of the ipsilateral dorsal root, and by a similarly protracted increase in the postsynaptic response of the DHs like LTP. It also is shown that LTPFC does not occur in the presence of APV, and becomes progressively smaller as [K+]o in the perfusion solution decreased from 3.0 mM to 0.0 mM. Interestingly LTPFC is reduced by bath application of Bic. Whole-cell patch recordings were carried out to evaluate the effects of FC on the response of DHs neurons to puffer-applied GABA. The observations reveal that transient exposure to FC is reliably accompanied by a prolonged (>1 hr) depolarizing shift of the equilibrium potential for the DHs neuron transmembrane ionic currents evoked by GABA. Considered collectively, the findings demonstrate that LTPFC involves (1) elevation of [K+]o in the DHs, (2) NMDAR activation, and (3) conversion of the effect of GABA on DHs neurons from inhibition to excitation. It is proposed that a transient impairment of astrocyte energy production can trigger the cascade of dorsal horn mechanisms that underlies hyperalgesia and persistent pain. PMID:24737940

  20. Collateral sprouting of uninjured primary afferent A-fibers into the superficial dorsal horn of the adult rat spinal cord after topical capsaicin treatment to the sciatic nerve.

    PubMed

    Mannion, R J; Doubell, T P; Coggeshall, R E; Woolf, C J

    1996-08-15

    That terminals of uninjured primary sensory neurons terminating in the dorsal horn of the spinal cord can collaterally sprout was first suggested by Liu and Chambers (1958), but this has since been disputed. Recently, horseradish peroxidase conjugated to the B subunit of cholera toxin (B-HRP) and intracellular HRP injections have shown that sciatic nerve section or crush produces a long-lasting rearrangement in the organization of primary afferent central terminals, with A-fibers sprouting into lamina II, a region that normally receives only C-fiber input (Woolf et al., 1992). The mechanism of this A-fiber sprouting has been thought to involve injury-induced C-fiber transganglionic degeneration combined with myelinated A-fibers being conditioned into a regenerative growth state. In this study, we ask whether C-fiber degeneration and A-fiber conditioning are both necessary for the sprouting of A-fibers into lamina II. Local application of the C-fiber-specific neurotoxin capsaicin to the sciatic nerve has previously been shown to result in C-fiber damage and degenerative atrophy in lamina II. We have used B-HRP to transganglionically label A-fiber central terminals and have shown that 2 weeks after topical capsaicin treatment to the sciatic nerve, the pattern of B-HRP staining in the dorsal horn is indistinguishable from that seen after axotomy, with lamina II displaying novel staining in the identical region containing capsaicin-treated C-fiber central terminals. These results suggest that after C-fiber injury, uninjured A-fiber central terminals can collaterally sprout into lamina II of the dorsal horn. This phenomenon may help to explain the pain associated with C-fiber neuropathy. PMID:8756447

  1. Calcium channel alpha-2-delta-1 protein upregulation in dorsal spinal cord mediates spinal cord injury induced neuropathic pain states

    PubMed Central

    Boroujerdi, Amin; Zeng, Jun; Sharp, Kelli; Kim, Donghyun; Steward, Oswald; Luo, Z. David

    2011-01-01

    Spinal cord injury (SCI) commonly results in the development of neuropathic pain, which can dramatically impair the quality of life for SCI patients. SCI induced neuropathic pain can be manifested as both tactile allodynia (a painful sensation to a non-noxious stimulus) and or hyperalgesia (an enhanced sensation to a painful stimulus). The mechanisms underlying these pain states are poorly understood. Clinical studies have shown that gabapentin, a drug that binds to the voltage gated calcium channel alpha-2-delta-1 subunit (Cavα2δ-1) proteins is effective in the management of SCI induced neuropathic pain. Accordingly, we hypothesized that tactile allodynia post SCI is mediated by an upregulation of Cavα2δ-1 in dorsal spinal cord (DSC). To test this hypothesis, we examined if SCI-induced dysregulation of spinal Cavα2δ-1 plays a contributory role in below-level allodynia development in a rat spinal T9 contusion injury model. We found that Cavα2δ-1 expression levels were significantly increased in L4-6 dorsal, but not ventral, spinal cord of SCI rats that correlated with tactile allodynia development in the hindpaw plantar surface. Furthermore, both intrathecal gabapentin treatment and blocking SCI induced Cavα2δ-1 protein upregulation by intrathecal Cavα2δ-1 antisense oligodeoxynucleotides could reverse tactile allodynia in SCI rats. These findings support that SCI induced Cavα2δ-1 upregulation in spinal dorsal horn is a key component in mediating below-level neuropathic pain development and selectively targeting this pathway may provide effective pain relief for SCI patients. PMID:21239111

  2. Spinal dorsal dermal sinus tract: An experience of 21 cases

    PubMed Central

    Singh, Ishwar; Rohilla, Seema; Kumar, Prashant; Sharma, Saurabh

    2015-01-01

    Background: Spinal dorsal dermal sinus is a rare entity, which usually comes to clinical attention by cutaneous abnormalities, neurologic deficit, and/or infection. The present study was undertaken to know the clinical profile of these patients, to study associated anomalies and to assess the results of surgical intervention. Methods: Medical records of 21 patients treated for spinal dorsal dermal sinus from September 2007 to December 2013 were reviewed. Results: We had 21 patients with male: female ratio of 13:8. Only 2 patients were below 1-year of age, and most cases (15) were between 2 and 15 years (mean age = 8.2 years). Lumbar region (11 cases) was most frequently involved, followed by thoracic (4 cases), lumbosacral, and cervical region in 3 patients each. All of our patients presented with neurological deficits. Three patients were admitted with acute meningitis with acute onset paraplegia and had intraspinal abscess. The motor, sensory, and autonomic deficits were seen in 14, 6, and 8 patients, respectively. Scoliosis and congenital talipes equinovarus were the common associated anomalies. All patients underwent surgical exploration and repair of dysraphic state and excision of the sinus. Overall, 20 patients improved or neurological status stabilized and only 1 patient deteriorated. Postoperative wound infection was seen in 2 cases. Conclusions: All patients with spinal dorsal dermal sinuses should be offered aggressive surgical treatment in the form of total excision of sinus tract and correction of spinal malformation, as soon as diagnosed. PMID:26539316

  3. Synaptic inhibition and disinhibition in the spinal dorsal horn.

    PubMed

    Prescott, Steven A

    2015-01-01

    Nociceptive signals originating in the periphery must be transmitted to the brain to evoke pain. Rather than being conveyed unchanged, those signals undergo extensive processing in the spinal dorsal horn. Synaptic inhibition plays a crucial role in that processing. On the one hand, neuropathy and inflammation are associated with reduced spinal inhibition; on the other hand, the hypersensitivity associated with inflammatory and neuropathic pain can be reproduced by blocking inhibition at the spinal level. To understand the consequences of disinhibition and how to therapeutically reverse it, one must understand how synaptic inhibition normally operates. To that end, this chapter will discuss the structure and function of GABAA and glycine receptors together with the role of associated molecules involved in transmitter handling and chloride regulation. Mechanisms by which inhibition modulates cellular excitability will be described. The chapter will end with discussion of how inhibition goes awry under pathological conditions and what the implications are for the treatment of resulting pain. PMID:25744679

  4. Characterization of blood flow in the mouse dorsal spinal venous system before and after dorsal spinal vein occlusion

    PubMed Central

    Farrar, Matthew J; Rubin, Jonathan D; Diago, Darcy M; Schaffer, Chris B

    2015-01-01

    The availability of transgenic strains has made the laboratory mouse a popular model for the study of healthy and diseased state spinal cord (SC). Essential to identifying physiologic and pathologic events is an understanding of the microvascular network and flow patterns of the SC. Using 2-photon excited fluorescence (2PEF) microscopy we performed in vivo measurements of blood flow in the lower thoracic portion of the mouse dorsal spinal vein (dSV) and in the first upstream branches supplying it, denoted as dorsal ascending venules (dAVs). We found that the dSV had large radiculomedullary veins (RMVs) exiting the SC, and that flow in the dSV between pairs of RMVs was bidirectional. Volumetric flow increased in each direction away from the point of bifurcation. Flow in the upstream dAVs varied with diameter in a manner consistent with a constant distal pressure source. By performing ex vivo 2PEF microscopy of fluorescent-gel perfused tissue, we created a 3-D map of the dorsal spinal vasculature. From these data, we constructed a simple model that predicted changes in the flow of upstream branches after occlusion of the dSV in different locations. Using an atraumatic model of dSV occlusion, we confirmed the predictions of this model in vivo. PMID:25564237

  5. Direct catecholaminergic innervation of spinal dorsal horn neurons with axons ascending the dorsal columns in cat.

    PubMed

    Doyle, C A; Maxwell, D J

    1993-05-15

    Previous ultrastructural studies have shown that catecholamine-containing nerve terminals in the spinal dorsal horn form synaptic junctions with dendrites and somata, but the identity of the neurons giving rise to these structures is largely unknown. In this study we have investigated the possibility that spinomedullary neurons, which project through the dorsal columns to the dorsal column nuclei, are synaptic targets for descending catecholaminergic axons. Neurons with axons ascending the dorsal columns were retrogradely labelled after uptake of horseradish peroxidase by their severed axons in the thoracic (T10-T12) or cervical (C2-C3) dorsal columns. After the retrogradely labelled neurons were visualized, the tissue was immunocytochemically stained with antisera raised against tyrosine hydroxylase or dopamine-beta-hydroxylase. Three hundred forty-three retrogradely labelled neurons within laminae III-V of the lumbosacral dorsal horn were examined under high power with the light microscope. In Triton X-100 treated material, over 60% of cells were found to have dopamine-beta-hydroxylase-immunoreactive varicosities closely apposed to their somata and proximal dendrites. The number of contacts per cell varied from 1 to 22, with a mean number of 4.5. Fewer cells (34%) received contacts from axons immunoreactive for tyrosine hydroxylase as a consequence of the weaker immunoreaction produced by this antiserum. Correlated light and electron microscopic analysis confirmed that many of these contacts were regions of synaptic specialization and that immunostained boutons contained pleomorphic (round to oval) agranular vesicles together with several dense core vesicles. These observations suggest that catecholamines regulate sensory transmission through this spinomedullary pathway by a direct postsynaptic action upon its cells of origin. Such an action would be predicted to suppress transmission generally through this pathway. PMID:8099918

  6. Effects of baclofen on mechanical noxious and innocuous transmission in the spinal dorsal horn of the adult rat: in vivo patch-clamp analysis.

    PubMed

    Fukuhara, Kaori; Katafuchi, Toshihiko; Yoshimura, Megumu

    2013-11-01

    The effects of a GABAB agonist, baclofen, on mechanical noxious and innocuous synaptic transmission in the substantia gelatinosa (SG) were investigated in adult rats with the in vivo patch-clamp technique. Under current-clamp conditions, perfusion with baclofen (10 μm) on the surface of the spinal cord caused hyperpolarisation of SG neurons and a decrease in the number of action potentials elicited by pinch and touch stimuli applied to the receptive field of the ipsilateral hindlimb. The suppression of action potentials was preserved under blockade of postsynaptic G-proteins, although baclofen-induced hyperpolarisation was completely blocked. These findings suggest presynaptic effects of baclofen on the induced action potentials. Under voltage-clamp conditions, application of baclofen reduced the frequency, but not the amplitude, of miniature excitatory postsynaptic currents (mEPSCs), whereas the GABAB receptor antagonist CGP55845 increased the frequency of mEPSCs without affecting the amplitude. Furthermore, application of a GABA uptake inhibitor, nipecotic acid, decreased the frequency of mEPSCs; this effect was blocked by CGP55845, but not by the GABAA antagonist bicuculline. Both the frequency and the amplitude of the pinch-evoked barrage of excitatory postsynaptic currents (EPSCs) were suppressed by baclofen in a dose-dependent manner. The frequency and amplitude of touch-evoked EPSCs was also suppressed by baclofen, but the suppression was significantly smaller than that of pinch-evoked EPSCs. We conclude that mechanical noxious transmission is presynaptically blocked through GABAB receptors in the SG, and is more effectively suppressed than innocuous transmission, which may account for a part of the mechanism of the efficient analgesic effects of baclofen. PMID:23961926

  7. Sensory and spinal inhibitory dorsal midline crossing is independent of Robo3

    PubMed Central

    Comer, John D.; Pan, Fong Cheng; Willet, Spencer G.; Haldipur, Parthiv; Millen, Kathleen J.; Wright, Christopher V. E.; Kaltschmidt, Julia A.

    2015-01-01

    Commissural neurons project across the midline at all levels of the central nervous system (CNS), providing bilateral communication critical for the coordination of motor activity and sensory perception. Midline crossing at the spinal ventral midline has been extensively studied and has revealed that multiple developmental lineages contribute to this commissural neuron population. Ventral midline crossing occurs in a manner dependent on Robo3 regulation of Robo/Slit signaling and the ventral commissure is absent in the spinal cord and hindbrain of Robo3 mutants. Midline crossing in the spinal cord is not limited to the ventral midline, however. While prior anatomical studies provide evidence that commissural axons also cross the midline dorsally, little is known of the genetic and molecular properties of dorsally-crossing neurons or of the mechanisms that regulate dorsal midline crossing. In this study, we describe a commissural neuron population that crosses the spinal dorsal midline during the last quarter of embryogenesis in discrete fiber bundles present throughout the rostrocaudal extent of the spinal cord. Using immunohistochemistry, neurotracing, and mouse genetics, we show that this commissural neuron population includes spinal inhibitory neurons and sensory nociceptors. While the floor plate and roof plate are dispensable for dorsal midline crossing, we show that this population depends on Robo/Slit signaling yet crosses the dorsal midline in a Robo3-independent manner. The dorsally-crossing commissural neuron population we describe suggests a substrate circuitry for pain processing in the dorsal spinal cord. PMID:26257608

  8. Sensory and spinal inhibitory dorsal midline crossing is independent of Robo3.

    PubMed

    Comer, John D; Pan, Fong Cheng; Willet, Spencer G; Haldipur, Parthiv; Millen, Kathleen J; Wright, Christopher V E; Kaltschmidt, Julia A

    2015-01-01

    Commissural neurons project across the midline at all levels of the central nervous system (CNS), providing bilateral communication critical for the coordination of motor activity and sensory perception. Midline crossing at the spinal ventral midline has been extensively studied and has revealed that multiple developmental lineages contribute to this commissural neuron population. Ventral midline crossing occurs in a manner dependent on Robo3 regulation of Robo/Slit signaling and the ventral commissure is absent in the spinal cord and hindbrain of Robo3 mutants. Midline crossing in the spinal cord is not limited to the ventral midline, however. While prior anatomical studies provide evidence that commissural axons also cross the midline dorsally, little is known of the genetic and molecular properties of dorsally-crossing neurons or of the mechanisms that regulate dorsal midline crossing. In this study, we describe a commissural neuron population that crosses the spinal dorsal midline during the last quarter of embryogenesis in discrete fiber bundles present throughout the rostrocaudal extent of the spinal cord. Using immunohistochemistry, neurotracing, and mouse genetics, we show that this commissural neuron population includes spinal inhibitory neurons and sensory nociceptors. While the floor plate and roof plate are dispensable for dorsal midline crossing, we show that this population depends on Robo/Slit signaling yet crosses the dorsal midline in a Robo3-independent manner. The dorsally-crossing commissural neuron population we describe suggests a substrate circuitry for pain processing in the dorsal spinal cord. PMID:26257608

  9. Photochemically induced spinal ischaemia: a model of spinal cord trauma in the rat

    NASA Astrophysics Data System (ADS)

    Olby, Natasha J.; Blakemore, W. F.

    1995-05-01

    Focal thrombosis was induced in the dorsal funiculus of the rat spinal cord by exposing the cord to light following intravenous injection of the photoactive dye, rose bengal. The light source was a 599 standing wave dye laser, pumped by an Innova 70 - 4 argon ion laser (Coherent Ltd, Cambridge, UK) and the light was delivered to the operative site via an optical fiber. The histological characteristics of the development and resolution of the lesion have been studied. Forty rats were examined with light and electron microscopy at various time points between 30 minutes and one month after irradiation and the lesion length was measured. Platelet aggregation, increased extracellular space in the white matter and vacuolation of the neurones and glia of the grey matter were present 30 minutes after injury. Progressive necrosis of the white and grey matter developed over the subsequent 24 hours to produce a fusiform lesion that occupied the dorsal funiculus and dorsal horns of the spinal cord at its center and tapered cranially and caudally along the dorsal columns for a total distance of seven millimeters. By one month after injury the area of necrosis had become a cyst lined by astrocytes ventrolaterally and meningeal cells dorsally. Measurements of lesion length showed a variability of 26%. This model of spinal cord trauma produces a lesion that is sufficiently reproducible to be suitable for performing studies aimed at tissue preservation and repair.

  10. Trigeminal and spinal dorsal horn (dis)continuity and avian evolution.

    PubMed

    Wild, J Martin; Krützfeldt, Nils O E; Altshuler, Douglas L

    2010-01-01

    The organization of the dorsal horn in the avian spinal cord differs in different species. For instance, in pigeons and doves, cranes, cuckoos, songbirds, ratites and tinamous, the dorsal horn is organized in laminar fashion, such that laminae II and III are sandwiched between lamina I dorsally and lamina IV ventrally, as they are in mammals and other nonavian amniotes. In most other avian species, including chickens, however, the organization of the dorsal horn is not strictly laminar, in that the structures homologous to laminae II and III lie side by side rather than in dorsoventral order. Because spinal and trigeminal dorsal horns are generally thought to be continuous, the question arises as to the organization of the trigeminal dorsal horn in these species. We examined this question in chickens, first by defining II and III of trigeminal and spinal dorsal horns using calcium-binding protein immunohistochemistry, and second by determining the caudal extent of the projections of the three branches of the trigeminal nerve using injections of cholera toxin B chain. It was found (1) that the trigeminal dorsal horn and the spinal dorsal horn of the first 2 cervical segments are organized in laminar fashion, but further caudally, II and III in the spinal dorsal horn gradually come to be arranged side by side and (2) that the descending trigeminal tract terminates no further caudal than the 3rd spinal segment. Therefore, unlike spinal nerves, trigeminal nerve branches do not project to II and III, once these cease to be organized in laminar fashion. These findings imply some kind or organizational discontinuity of trigeminal and spinal dorsal horns in the chicken and perhaps in other species with a side-by-side arrangement of II and III. It has also been suggested that the condition in which the spinal dorsal horn structures homologous to laminae II and II lie side by side may define a novel clade of birds. This suggestion was reexamined within the context of a

  11. Spinal dorsal horn neuronal responses to myelinated versus unmyelinated heat nociceptors and their modulation by activation of the periaqueductal grey in the rat.

    PubMed

    McMullan, Simon; Lumb, Bridget M

    2006-10-15

    The aim of this study was to further understand the central processing of inputs arising from unmyelinated and myelinated nociceptors by (i) determining the response characteristics of Class 2 dorsal horn neurones to preferential activation of C- and A-fibre heat nociceptors, and (ii) investigating the control exerted by the dorsolateral/lateral region of the midbrain periaqueductal grey (DL/L-PAG) on C- and A-fibre-evoked responses of these neurones. The use of different rates of skin heating to preferentially activate unmyelinated (C-fibre; 2.5 degrees C s(-1)) versus myelinated (A-fibre; 7.5 degrees C s(-1)) heat nociceptors revealed that, in response to C-nociceptor activation, Class 2 neurones encode well only over the first 5 degrees C above threshold, and that at higher temperatures responses decline. In contrast, responses to A-nociceptor activation are linear and encode skin temperature over more than 10 degrees C, and almost certainly into the tissue-damaging range. PAG stimulation raised thresholds and decreased significantly the magnitude of responses to A- and C-nociceptor activation. However, differences were revealed in the effects of descending control on the relationships between skin temperature and neuronal firing rate; the linear relationship that occurred over the first 5 degrees C of slow rates of skin heating was no longer evident, whereas that to fast rates of skin heating was maintained over the entire range, albeit shifted to the right. These data indicate that the sensori-discriminative information conveyed in A-fibre nociceptors is maintained and that the information from C-nociceptors is lost in the presence of descending control from the DL/L-PAG. The data are discussed in relation to the role of the DL/L-PAG in mediating active coping strategies. PMID:16916903

  12. Changes in Synaptic Populations in the Spinal Dorsal Horn Following a Dorsal Rhizotomy in the Monkey

    PubMed Central

    Darian-Smith, Corinna; Hopkins, Stephanie; Ralston, Henry J.

    2010-01-01

    Studies in monkeys have shown substantial neuronal reorganization and behavioral recovery during the months following a cervical dorsal root lesion (DRL; Darian-Smith [2004] J. Comp. Neurol. 470:134–150; Darian-Smith and Ciferri [2005] J. Comp. Neurol. 491:27–45, [2006] J. Comp. Neurol. 498:552–565). The goal of the present study was to identify ultrastructural synaptic changes post-DRL within the dorsal horn (DH). Two monkeys received a unilateral DRL, as described previously (Darian-Smith and Brown [2000] Nat. Neurosci. 3:476–481), which removed cutaneous and proprioceptive input from the thumb, index finger, and middle finger. Six weeks before terminating the experiment at 4 post-DRL months, hand representation was mapped electrophysiologically within the somatosensory cortex, and anterograde tracers were injected into reactivated cortex to label corticospinal terminals. Sections were collected through the spinal lesion zone. Corticospinal terminals and inhibitory profiles were visualized by using preembedding immunohistochemistry and postembedding γ-aminobutyric acid (GABA) immunostaining, respectively. Synaptic elements were systematically counted through the superficial DH and included synaptic profiles with round vesicles (R), pleomorphic flattened vesicles (F; presumed inhibitory synapses), similar synapses immunolabeled for GABA (F-GABA), primary afferent synapses (C-type), synapses with dense-cored vesicles (D, mostly primary afferents), and presynaptic dendrites of interneurons (PSD). Synapse types were compared bilaterally via ANOVAs. As expected, we found a significant drop in C-type profiles on the lesioned side (~16% of contralateral), and R profiles did not differ bilaterally. More surprising was a significant increase in the number of F profiles (~170% of contralateral) and F-GABA profiles (~315% of contralateral) on the side of the lesion. Our results demonstrate a striking increase in the inhibitory circuitry within the deafferented DH

  13. Pulsed electrical stimulation protects neurons in the dorsal root and anterior horn of the spinal cord after peripheral nerve injury

    PubMed Central

    Pei, Bao-an; Zi, Jin-hua; Wu, Li-sheng; Zhang, Cun-hua; Chen, Yun-zhen

    2015-01-01

    Most studies on peripheral nerve injury have focused on repair at the site of injury, but very few have examined the effects of repair strategies on the more proximal neuronal cell bodies. In this study, an approximately 10-mm-long nerve segment from the ischial tuberosity in the rat was transected and its proximal and distal ends were inverted and sutured. The spinal cord was subjected to pulsed electrical stimulation at T10 and L3, at a current of 6.5 mA and a stimulation frequency of 15 Hz, 15 minutes per session, twice a day for 56 days. After pulsed electrical stimulation, the number of neurons in the dorsal root ganglion and anterior horn was increased in rats with sciatic nerve injury. The number of myelinated nerve fibers was increased in the sciatic nerve. The ultrastructure of neurons in the dorsal root ganglion and spinal cord was noticeably improved. Conduction velocity of the sciatic nerve was also increased. These results show that pulsed electrical stimulation protects sensory neurons in the dorsal root ganglia as well as motor neurons in the anterior horn of the spinal cord after peripheral nerve injury, and that it promotes the regeneration of peripheral nerve fibers. PMID:26692864

  14. Pulsed electrical stimulation protects neurons in the dorsal root and anterior horn of the spinal cord after peripheral nerve injury.

    PubMed

    Pei, Bao-An; Zi, Jin-Hua; Wu, Li-Sheng; Zhang, Cun-Hua; Chen, Yun-Zhen

    2015-10-01

    Most studies on peripheral nerve injury have focused on repair at the site of injury, but very few have examined the effects of repair strategies on the more proximal neuronal cell bodies. In this study, an approximately 10-mm-long nerve segment from the ischial tuberosity in the rat was transected and its proximal and distal ends were inverted and sutured. The spinal cord was subjected to pulsed electrical stimulation at T10 and L3, at a current of 6.5 mA and a stimulation frequency of 15 Hz, 15 minutes per session, twice a day for 56 days. After pulsed electrical stimulation, the number of neurons in the dorsal root ganglion and anterior horn was increased in rats with sciatic nerve injury. The number of myelinated nerve fibers was increased in the sciatic nerve. The ultrastructure of neurons in the dorsal root ganglion and spinal cord was noticeably improved. Conduction velocity of the sciatic nerve was also increased. These results show that pulsed electrical stimulation protects sensory neurons in the dorsal root ganglia as well as motor neurons in the anterior horn of the spinal cord after peripheral nerve injury, and that it promotes the regeneration of peripheral nerve fibers. PMID:26692864

  15. Interferon-gamma induced disruption of GABAergic inhibition in the spinal dorsal horn in vivo.

    PubMed

    Vikman, Kristina S; Duggan, Arthur W; Siddall, Philip J

    2007-12-15

    The proinflammatory cytokine interferon-gamma (IFN-gamma), which can be present in elevated levels in the central nervous system during pathological conditions, may be involved in the generation of persistent pain states by inducing neuronal hyperexcitability. The aim of the present study was to examine whether loss of dorsal horn GABAergic inhibition may underlie this IFN-gamma-mediated neuronal hyperexcitability. Repetitive intrathecal injections of recombinant rat IFN-gamma (1000 U) or control buffer were administered to rats every second day for eight days. Electrophysiological recordings from lumbar dorsal horn neurons (n=46) were performed under halothane anaesthesia. Cellular responses were recorded before, during and after microiontophoretic application of the GABA antagonist bicuculline. In control animals, all cellular responses studied were significantly enhanced in the presence of bicuculline, including increased spontaneous activity, enhanced responses to innocuous and noxious mechanical stimulation and reduced paired-pulse depression. In contrast, in IFN-gamma-treated animals, bicuculline ejection had little or no facilitating effect on neuronal responses and instead a significant proportion of neurons displayed reduced responses. Seventy-four percent of cells from IFN-gamma treated animals showed a reduction in the response to noxious stimulation and 47% of the cells showed increased rather than reduced paired-pulse depression in the presence of bicuculline, thus suggesting IFN-gamma-induced excitatory actions by GABA. These findings show that the prolonged presence of increased levels of IFN-gamma in the central nervous system may contribute to the generation of central sensitization and persistent pain by reducing inhibitory tone in the dorsal horn. This implies a potential link between disinhibition and cytokine action in the spinal cord. PMID:17407800

  16. Neuroimmune and Neuropathic Responses of Spinal Cord and Dorsal Root Ganglia in Middle Age

    PubMed Central

    Galbavy, William; Kaczocha, Martin; Puopolo, Michelino; Liu, Lixin; Rebecchi, Mario J.

    2015-01-01

    Prior studies of aging and neuropathic injury have focused on senescent animals compared to young adults, while changes in middle age, particularly in the dorsal root ganglia (DRG), have remained largely unexplored. 14 neuroimmune mRNA markers, previously associated with peripheral nerve injury, were measured in multiplex assays of lumbar spinal cord (LSC), and DRG from young and middle-aged (3, 17 month) naïve rats, or from rats subjected to chronic constriction injury (CCI) of the sciatic nerve (after 7 days), or from aged-matched sham controls. Results showed that CD2, CD3e, CD68, CD45, TNF-α, IL6, CCL2, ATF3 and TGFβ1 mRNA levels were substantially elevated in LSC from naïve middle-aged animals compared to young adults. Similarly, LSC samples from older sham animals showed increased levels of T-cell and microglial/macrophage markers. CCI induced further increases in CCL2, and IL6, and elevated ATF3 mRNA levels in LSC of young and middle-aged adults. Immunofluorescence images of dorsal horn microglia from middle-aged naïve or sham rats were typically hypertrophic with mostly thickened, de-ramified processes, similar to microglia following CCI. Unlike the spinal cord, marker expression profiles in naïve DRG were unchanged across age (except increased ATF3); whereas, levels of GFAP protein, localized to satellite glia, were highly elevated in middle age, but independent of nerve injury. Most neuroimmune markers were elevated in DRG following CCI in young adults, yet middle-aged animals showed little response to injury. No age-related changes in nociception (heat, cold, mechanical) were observed in naïve adults, or at days 3 or 7 post-CCI. The patterns of marker expression and microglial morphologies in healthy middle age are consistent with development of a para-inflammatory state involving microglial activation and T-cell marker elevation in the dorsal horn, and neuronal stress and satellite cell activation in the DRG. These changes, however, did not

  17. Growth-associated protein 43 immunoreactivity in the superficial dorsal horn of the rat spinal cord is localized in atrophic C-fiber, and not in sprouted A-fiber, central terminals after peripheral nerve injury.

    PubMed

    Doubell, T P; Woolf, C J

    1997-09-15

    Peripheral nerve injury induces the up-regulation in dorsal root ganglion cells of growth-associated protein 43 (GAP-43) and its transport to the superficial laminae of the dorsal horn of the spinal cord, where it is located primarily in unmyelinated axons and growth-cone like structures. Peripheral nerve injury also induces the central terminals of axotomized myelinated axons to sprout and form novel synaptic contacts in lamina II of the dorsal horn. To investigate whether the sprouting of A-fiber central terminals into lamina II is the consequence of GAP-43 incorporation into their terminal membranes, we have used an ultrastructural analysis with double labelling to identify the localization of GAP-43 immunoreactivity. Transganglionic transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) was used to identify C-fiber terminals. Transganglionic transport of the B fragment of cholera toxin conjugated to horseradish peroxidase (B-HRP) was used to label A-fiber sciatic nerve central terminals in combination with GAP-43 immunocytochemistry. GAP-43 was found to colocalize only with WGA-HRP- and not with B-HRP-labelled synapses or axons. In addition, many single-labelled GAP-43 synapses were observed. Many of the WGA-HRP-labelled terminals that were characterized by degenerative changes were GAP-43 immunoreactive. Our results indicate that peripheral nerve injury induces novel synapse formation of A fibers in lamina II but that up-regulated levels of GAP-43 are present mainly in other axon projections to the superficial dorsal horn. PMID:9303528

  18. Slow dorsal-ventral rhythm generator in the lamprey spinal cord.

    PubMed

    Aoki, F; Wannier, T; Grillner, S

    2001-01-01

    In the isolated lamprey spinal cord, a very slow rhythm (0.03-0.11 Hz), superimposed on fast N-methyl-D-aspartate (NMDA)-induced locomotor activity (0.26-2.98 Hz), could be induced by a blockade of GABA(A) or glycine receptors or by administration of (1 s, 3 s)-l-aminocyclopentane-1,3-dicarboxylic acid a metabotropic glutamate receptor agonist. Ventral root branches supplying dorsal and ventral myotomes were exposed bilaterally to study the motor pattern in detail. The slow rhythm was expressed in two main forms: 1) a dorsal-ventral reciprocal pattern was the most common (18 of 24 preparations), in which bilateral dorsal branches were synchronous and alternated with the ventral branches, in two additional cases a diagonal dorsal-ventral reciprocal pattern with alternation between the left (or right) dorsal and the right (or left) ventral branches was observed; 2) synchronous bursting in all branches was encountered in four cases. In contrast, the fast locomotor rhythm occurred always in a left-right reciprocal pattern. Thus when the slow rhythm appeared in a dorsal-ventral reciprocal pattern, fast rhythms would simultaneously display left-right alternation. A longitudinal midline section of the spinal cord during ongoing slow bursting abolished the reciprocal pattern between ipsilateral dorsal and ventral branches but a synchronous burst activity could still remain. The fast swimming rhythm did not recover after the midline section. These results suggest that in addition to the network generating the swimming rhythm in the lamprey spinal cord, there is also a network providing slow reciprocal alternation between dorsal and ventral parts of the myotome. During steering, a selective activation of dorsal and ventral myotomes is required and the neural network generating the slow rhythm may represent activity in the spinal machinery used for steering. PMID:11152721

  19. A novel transverse push-pull microprobe: in vitro characterization and in vivo demonstration of the enzymatic production of adenosine in the spinal cord dorsal horn.

    PubMed

    Patterson, S L; Sluka, K A; Arnold, M A

    2001-01-01

    Adenosine produces analgesia in the spinal cord and can be formed extracellularly through enzymatic conversion of adenine nucleotides. A transverse push-pull microprobe was developed and characterized to sample extracellular adenosine concentrations of the dorsal horn of the rat spinal cord. Samples collected via this sampling technique reveal that AMP is converted to adenosine in the dorsal horn. This conversion is decreased by the ecto-5'-nucleotidase inhibitor, alpha,beta-methylene ADP. Related behavioral studies demonstrate that AMP administered directly to the spinal cord can reverse the secondary mechanical hyperalgesia characteristic of the intradermal capsaicin model of inflammatory pain. The specific adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dimethylxanthine (CPT) inhibits the antihyperalgesia produced by AMP. This research introduces a novel microprobe that can be used as an adjunct sampling technique to microdialysis and push-pull cannulas. Furthermore, we conclude that AMP is converted to adenosine in the dorsal horn of the spinal cord by ecto-5'-nucleotidase and subsequently may be one source of adenosine, acting through adenosine A(1) receptors in the dorsal horn of the spinal cord, which produce antihyperalgesia. PMID:11145997

  20. A central role for spinal dorsal horn neurons that express neurokinin-1 receptors in chronic itch

    PubMed Central

    Akiyama, Tasuku; Nguyen, Tony; Curtis, Eric; Nishida, Katsuko; Devireddy, Jahnavi; Delahanty, Jeremy; Carstens, Mirela Iodi; Carstens, E.

    2015-01-01

    We investigated roles for spinal neurons expressing the neurokinin-1 receptor (NK1R) and/or gastrin releasing peptide receptor (GRPR) in a mouse model of ovalbumin (OVA)-induced chronic atopic dermatitis (AD). Mice receiving repeated topical application of OVA exhibited atopic-like skin lesions and behavioral signs of chronic itch including spontaneous scratching, touch-evoked scratching (alloknesis), and enhancement of chloroquine-evoked scratching (hyperknesis). Substance P-saporin (SP-SAP) and bombesin-saporin (BB-SAP) were intrathecally injected into OVA-sensitized mice to neurotoxically ablate NK1R- or GRPR-expressing spinal neurons, respectively. SP-SAP diminished the expression of NK1R in the superficial spinal dorsal horn, and significantly attenuated all behavioral signs of chronic itch. BB-SAP reduced the spinal dorsal horn expression of GRPR and significantly attenuated hyperknesis, with no effect on spontaneous scratching or alloknesis. To investigate whether NK1R-expressing spinal neurons project in ascending somatosensory pathways, we performed a double-label study. The retrograde tracer, Fluorogold (FG), was injected into either the somatosensory thalamus or lateral parabrachial nucleus. In the upper cervical (C1-2) spinal cord, most neurons retrogradely labeled with FG were located in the dorsomedial aspect of the superficial dorsal horn. Of FG-labeled spinal neurons, 89-94% were double-labeled for NK1R. These results indicate that NK1R-expressing spinal neurons play a major role in the expression of symptoms of chronic itch, and give rise to ascending somatosensory projections. GRPR-expressing spinal neurons contribute to hyperknesis but not alloknesis or ongoing itch. NK1R-expressing spinal neurons represent a potential target to treat chronic itch. PMID:25830923

  1. Time Course of Substance P Expression in Dorsal Root Ganglia Following Complete Spinal Nerve Transection

    PubMed Central

    Weissner, Wendy; Winterson, Barbara J.; Stuart-Tilley, Alan; Devor, Marshall; Bove, Geoffrey M.

    2008-01-01

    Recent evidence suggests that substance P (SP) is upregulated in primary sensory neurons following axotomy, and that this change occurs in larger neurons that do not usually produce SP. If so, this upregulation may allow normally neighboring, uninjured, and non-nociceptive dorsal root ganglion (DRG) neurons to become effective in activating pain pathways. Using immunohistochemistry, we performed a unilateral L5 spinal nerve transection upon male Wistar rats, and measured SP expression in ipsilateral L4 and L5 DRGs and contralateral L5 DRGs, at 1 to 14 days postoperatively (dpo), and in control and sham operated rats. In normal and sham operated DRGs, SP was detectable almost exclusively in small neurons (≤ 800 μm2). Following surgery, the mean size of SP-positive neurons from the axotomized L5 ganglia was greater at 2, 4, 7 and 14 dpo. Among large neurons (> 800 μm2) from the axotomized L5, the percentage of SP-positive neurons increased at 2, 4, 7, and 14 dpo. Among small neurons from the axotomized L5, the percentage of SP-positive neurons was increased at 1 and 3 dpo, but was decreased at 7 and 14 dpo. Thus, SP expression is affected by axonal damage, and the time course of the expression is different between large and small DRG neurons. These data support a role of SP-producing, large DRG neurons in persistent sensory changes due to nerve injury. PMID:16680762

  2. Noxious mechanical heterotopic stimulation induces inhibition of the spinal dorsal horn neuronal network: analysis of spinal somatosensory-evoked potentials.

    PubMed

    Meléndez-Gallardo, J; Eblen-Zajjur, A

    2016-09-01

    Most of the endogenous pain modulation (EPM) involves the spinal dorsal horn (SDH). EPM including diffuse noxious inhibitory controls have been extensively described in oligoneuronal electrophysiological recordings but less attention had been paid to responses of the SDH neuronal population to heterotopic noxious stimulation (HNS). Spinal somatosensory-evoked potentials (SEP) offer the possibility to evaluate the neuronal network behavior, reflecting the incoming afferent volleys along the entry root, SDH interneuron activities and the primary afferent depolarization. SEP from de lumbar cord dorsum were evaluated during mechanical heterotopic noxious stimuli. Sprague-Dawley rats (n = 12) were Laminectomized (T10-L3). The sural nerve of the left hind paw was electrically stimulated (5 mA, 0.5 ms, 0.05 Hz) to induce lumbar SEP. The HNS (mechanic clamp) was applied sequentially to the tail, right hind paw, right forepaw, muzzle and left forepaw during sural stimulation. N wave amplitude decreases (-16.6 %) compared to control conditions when HNS was applied to all areas of stimulation. This effect was more intense for muzzle stimulation (-23.5 %). N wave duration also decreased by -23.6 %. HNS did not change neither the amplitude nor the duration of the P wave but dramatically increases the dispersion of these two parameters. The results of the present study strongly suggest that a HNS applied to different parts of the body is able to reduce the integrated electrical response of the SDH, suggesting that not only wide dynamic range neurons but many others in the SDH are modulated by the EPM. PMID:27207681

  3. Select spinal lesions reveal multiple ascending pathways in the rat conveying input from the male genitalia.

    PubMed

    Hubscher, C H; Reed, W R; Kaddumi, E G; Armstrong, J E; Johnson, R D

    2010-04-01

    The specific white matter location of all the spinal pathways conveying penile input to the rostral medulla is not known. Our previous studies using rats demonstrated the loss of low but not high threshold penile inputs to medullary reticular formation (MRF) neurons after acute and chronic dorsal column (DC) lesions of the T8 spinal cord and loss of all penile inputs after lesioning the dorsal three-fifths of the cord. In the present study, select T8 lesions were made and terminal electrophysiological recordings were performed 45-60 days later in a limited portion of the nucleus reticularis gigantocellularis (Gi) and Gi pars alpha. Lesions included subtotal dorsal hemisections that spared only the lateral half of the dorsal portion of the lateral funiculus on one side, dorsal and over-dorsal hemisections, and subtotal transections that spared predominantly just the ventromedial white matter. Electrophysiological data for 448 single unit recordings obtained from 32 urethane-anaesthetized rats, when analysed in groups based upon histological lesion reconstructions, revealed (1) ascending bilateral projections in the dorsal, dorsolateral and ventrolateral white matter of the spinal cord conveying information from the male external genitalia to MRF, and (2) ascending bilateral projections in the ventrolateral white matter conveying information from the pelvic visceral organs (bladder, descending colon, urethra) to MRF. Multiple spinal pathways from the penis to the MRF may correspond to different functions, including those processing affective/pleasure/motivational, nociception, and mating-specific (such as for erection and ejaculation) inputs. PMID:20142271

  4. Alterations of spinal dorsal horn substance P following electroacupuncture analgesia--a study of the formalin test with immunohistochemistry and densitometry.

    PubMed

    Du, J; He, L

    1992-01-01

    Substance P (SP), released from thin afferent terminals, is believed to be a neurotransmitter for pain transmission in the spinal dorsal horn. It has been demonstrated that in addition to analgesia, morphine increases the accumulation of SP possibly due to the inhibition of its release. The present work investigated the level of spinal SP like immunoreactivity (SPLI) following electroacupuncture analgesia in rats using immunohistochemistry and image analysis. Experiment results revealed that formalin injected into the hind paw elicited marked pain response and accumulation of SP in the spinal dorsal horn. Electroacupuncture of Tsu-San-Li could depress the pain response, however increasing further the SP accumulation. It is thus suggested that pain stimulation itself may activate the endogenous opioid mechanism to inhibit SP release and acupuncture is able to enhance the process. This may be one mechanism of acupuncture analgesia. PMID:1376550

  5. Measuring Spinal Presynaptic Inhibition in Mice By Dorsal Root Potential Recording In Vivo

    PubMed Central

    Grünewald, Benedikt; Geis, Christian

    2014-01-01

    Presynaptic inhibition is one of the most powerful inhibitory mechanisms in the spinal cord. The underlying physiological mechanism is a depolarization of primary afferent fibers mediated by GABAergic axo-axonal synapses (primary afferent depolarization). The strength of primary afferent depolarization can be measured by recording of volume-conducted potentials at the dorsal root (dorsal root potentials, DRP). Pathological changes of presynaptic inhibition are crucial in the abnormal central processing of certain pain conditions and in some disorders of motor hyperexcitability. Here, we describe a method of recording DRP in vivo in mice. The preparation of spinal cord dorsal roots in the anesthetized animal and the recording procedure using suction electrodes are explained. This method allows measuring GABAergic DRP and thereby estimating spinal presynaptic inhibition in the living mouse. In combination with transgenic mouse models, DRP recording may serve as a powerful tool to investigate disease-associated spinal pathophysiology. In vivo recording has several advantages compared to ex vivo isolated spinal cord preparations, e.g. the possibility of simultaneous recording or manipulation of supraspinal networks and induction of DRP by stimulation of peripheral nerves. PMID:24747664

  6. Loss of Hoxb8 alters spinal dorsal laminae and sensory responses in mice

    PubMed Central

    Holstege, Jan C.; de Graaff, Wim; Hossaini, Mehdi; Cano, Sebastian Cardona; Jaarsma, Dick; van den Akker, Eric; Deschamps, Jacqueline

    2008-01-01

    Although Hox gene expression has been linked to motoneuron identity, a role of these genes in development of the spinal sensory system remained undocumented. Hoxb genes are expressed at high levels in the dorsal horn of the spinal cord. Hoxb8 null mutants manifest a striking phenotype of excessive grooming and hairless lesions on the lower back. Applying local anesthesia underneath the hairless skin suppressed excessive grooming, indicating that this behavior depends on peripheral nerve activity. Functional ablation of mouse Hoxb8 also leads to attenuated response to nociceptive and thermal stimuli. Although spinal ganglia were normal, a lower postmitotic neural count was found in the dorsalmost laminae at lumbar levels around birth, leading to a smaller dorsal horn and a correspondingly narrowed projection field of nociceptive and thermoceptive afferents. The distribution of the dorsal neuronal cell types that we assayed, including neurons expressing the itch-specific gastrin-releasing peptide receptor, was disorganized in the lumbar region of the mutant. BrdU labeling experiments and gene-expression studies at stages around the birth of these neurons suggest that loss of Hoxb8 starts impairing development of the upper laminae of the lumbar spinal cord at approximately embryonic day (E)15.5. Because none of the neuronal markers used was unexpressed in the adult dorsal horn, absence of Hoxb8 does not impair neuronal differentiation. The data therefore suggest that a lower number of neurons in the upper spinal laminae and neuronal disorganization in the dorsal horn underlie the sensory defects including the excessive grooming of the Hoxb8 mutant. PMID:18430798

  7. Loss of Hoxb8 alters spinal dorsal laminae and sensory responses in mice.

    PubMed

    Holstege, Jan C; de Graaff, Wim; Hossaini, Mehdi; Cardona Cano, Sebastian; Jaarsma, Dick; van den Akker, Eric; Deschamps, Jacqueline

    2008-04-29

    Although Hox gene expression has been linked to motoneuron identity, a role of these genes in development of the spinal sensory system remained undocumented. Hoxb genes are expressed at high levels in the dorsal horn of the spinal cord. Hoxb8 null mutants manifest a striking phenotype of excessive grooming and hairless lesions on the lower back. Applying local anesthesia underneath the hairless skin suppressed excessive grooming, indicating that this behavior depends on peripheral nerve activity. Functional ablation of mouse Hoxb8 also leads to attenuated response to nociceptive and thermal stimuli. Although spinal ganglia were normal, a lower postmitotic neural count was found in the dorsalmost laminae at lumbar levels around birth, leading to a smaller dorsal horn and a correspondingly narrowed projection field of nociceptive and thermoceptive afferents. The distribution of the dorsal neuronal cell types that we assayed, including neurons expressing the itch-specific gastrin-releasing peptide receptor, was disorganized in the lumbar region of the mutant. BrdU labeling experiments and gene-expression studies at stages around the birth of these neurons suggest that loss of Hoxb8 starts impairing development of the upper laminae of the lumbar spinal cord at approximately embryonic day (E)15.5. Because none of the neuronal markers used was unexpressed in the adult dorsal horn, absence of Hoxb8 does not impair neuronal differentiation. The data therefore suggest that a lower number of neurons in the upper spinal laminae and neuronal disorganization in the dorsal horn underlie the sensory defects including the excessive grooming of the Hoxb8 mutant. PMID:18430798

  8. Spinal dorsal horn neuron response to mechanical stimuli is decreased by electrical stimulation of the primary motor cortex.

    PubMed

    Senapati, Arun K; Huntington, Paula J; Peng, Yuan B

    2005-03-01

    Motor cortex stimulation (MCS) has been used clinically as a tool for the control for central post-stroke pain and neuropathic facial pain. The underlying mechanisms involved in the antinociceptive effect of MCS are not clearly understood. We hypothesize that the antinociceptive effect is through the modulation of the spinal dorsal horn neuron activity. Thirty-two wide dynamic range spinal dorsal horn neurons were recorded, in response to graded mechanical stimulation (brush, pressure, and pinch) at their respective receptive fields, while a stepwise electrical stimulation was applied simultaneously in the motor cortex. The responses to brush at control, 10 V, 20 V, and 30 V, and recovery were 11.5+/-1.6, 12.1+/-2.6, 11.1+/-2.2, 10.5+/-2.1, and 13.2+/-2.5 spikes/s, respectively. The responses to pressure at control, 10 V, 20 V, and 30 V, and recovery were 33.2+/-6.1, 22.9+/-5.3, 20.5+/-5.0, 17.3+/-3.8, and 27.0+/-4.0 spikes/s, respectively. The responses to pinch at control, 10 V, 20 V, and 30 V, and recovery were 37.2+/-6.4, 26.3+/-4.7, 25.9+/-4.7, 22.5+/-4.3, and 35.0+/-6.2 spikes/s, respectively. It is concluded that, in the rat, electrical stimulation of the motor cortex produces significant transient inhibition of the responses of spinal cord dorsal horn neurons to higher intensity mechanical stimuli without affecting their response to an innocuous stimulus. PMID:15725415

  9. Allodynia-like effects in rat after ischaemic spinal cord injury photochemically induced by laser irradiation.

    PubMed

    Hao, J X; Xu, X J; Aldskogius, H; Seiger, A; Wiesenfeld-Hallin, Z

    1991-05-01

    involve the sympathetic system. Histological examination of allodynic animals 3 days after spinal cord injury revealed considerable morphological damage in the dorsal spinal cord of a rat irradiated for 5 min. The related dorsal roots were also slightly affected in this animal, while the dorsal root ganglia were normal. However, in rats irradiated for 1 min, despite the existence of strong allodynia, no damage could be found at this time in the spinal cord, dorsal roots or dorsal root ganglia. It is suggested that functional deficits in the GABAB system in the spinal cord may be related to this allodynia-like phenomenon.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:1652116

  10. Dorsal and ventral respiratory groups of neurons in the medulla of the rat.

    PubMed

    Saether, K; Hilaire, G; Monteau, R

    1987-09-01

    The aim of the present work was to identify and localize in rat the medullary neurons involved in respiration. Neural activity was recorded in ketamine-anesthetized, paralyzed and artificially ventilated rats. Active sites were marked by electrocoagulation. Neurons firing in relation to phrenic nerve activity were located between 0.5 and 2 mm lateral to the midline, extending from 0.5 mm caudal to 2 mm rostral to the posterior end of the area postrema. Two groups of respiratory neurons were found: a dorsal group located ventrolateral to the tractus solitarius and a ventral group located in the ventrolateral reticular formation close to the nucleus ambiguus. Neurons were classified as bulbospinal or laryngeal if stimulation of the spinal cord or the vagus nerve, respectively, elicited antidromic action potentials, or as propriobulbar if they were not activated. Neurons firing synchronously with lung inflation were termed pump (P) cells. The dorsal respiratory group includes inspiratory (I) bulbospinal and propriobulbar neurons, P cells, but few expiratory (E) propriobulbar neurons. The ventral respiratory group includes bulbospinal, laryngeal and propriobulbar I and E neurons. Laryngeal motoneurons project ipsilaterally whereas bulbospinal neurons project contralaterally. Cross-correlations between inspiratory bulbospinal neuronal activity and phrenic discharge suggest that bulbospinal I neurons of dorsal and ventral groups project monosynaptically to contralateral phrenic motoneurons. These results indicate a similarity of the medullary respiratory centers of rats and cats, suggesting that rats may profitably be used in studies of respiratory rhythmogenesis. PMID:3676744

  11. Dysregulation of Kv3.4 channels in dorsal root ganglia following spinal cord injury.

    PubMed

    Ritter, David M; Zemel, Benjamin M; Hala, Tamara J; O'Leary, Michael E; Lepore, Angelo C; Covarrubias, Manuel

    2015-01-21

    Spinal cord injury (SCI) patients develop chronic pain involving poorly understood central and peripheral mechanisms. Because dysregulation of the voltage-gated Kv3.4 channel has been implicated in the hyperexcitable state of dorsal root ganglion (DRG) neurons following direct injury of sensory nerves, we asked whether such a dysregulation also plays a role in SCI. Kv3.4 channels are expressed in DRG neurons, where they help regulate action potential (AP) repolarization in a manner that depends on the modulation of inactivation by protein kinase C (PKC)-dependent phosphorylation of the channel's inactivation domain. Here, we report that, 2 weeks after cervical hemicontusion SCI, injured rats exhibit contralateral hypersensitivity to stimuli accompanied by accentuated repetitive spiking in putative DRG nociceptors. Also in these neurons at 1 week after laminectomy and SCI, Kv3.4 channel inactivation is impaired compared with naive nonsurgical controls. At 2-6 weeks after laminectomy, however, Kv3.4 channel inactivation returns to naive levels. Conversely, Kv3.4 currents at 2-6 weeks post-SCI are downregulated and remain slow-inactivating. Immunohistochemistry indicated that downregulation mainly resulted from decreased surface expression of the Kv3.4 channel, as whole-DRG-protein and single-cell mRNA transcript levels did not change. Furthermore, consistent with Kv3.4 channel dysregulation, PKC activation failed to shorten the AP duration of small-diameter DRG neurons. Finally, re-expressing synthetic Kv3.4 currents under dynamic clamp conditions dampened repetitive spiking in the neurons from SCI rats. These results suggest a novel peripheral mechanism of post-SCI pain sensitization implicating Kv3.4 channel dysregulation and potential Kv3.4-based therapeutic interventions. PMID:25609640

  12. Dysregulation of Kv3.4 Channels in Dorsal Root Ganglia Following Spinal Cord Injury

    PubMed Central

    Ritter, David M.; Zemel, Benjamin M.; Hala, Tamara J.; O'Leary, Michael E.; Lepore, Angelo C.

    2015-01-01

    Spinal cord injury (SCI) patients develop chronic pain involving poorly understood central and peripheral mechanisms. Because dysregulation of the voltage-gated Kv3.4 channel has been implicated in the hyperexcitable state of dorsal root ganglion (DRG) neurons following direct injury of sensory nerves, we asked whether such a dysregulation also plays a role in SCI. Kv3.4 channels are expressed in DRG neurons, where they help regulate action potential (AP) repolarization in a manner that depends on the modulation of inactivation by protein kinase C (PKC)-dependent phosphorylation of the channel's inactivation domain. Here, we report that, 2 weeks after cervical hemicontusion SCI, injured rats exhibit contralateral hypersensitivity to stimuli accompanied by accentuated repetitive spiking in putative DRG nociceptors. Also in these neurons at 1 week after laminectomy and SCI, Kv3.4 channel inactivation is impaired compared with naive nonsurgical controls. At 2–6 weeks after laminectomy, however, Kv3.4 channel inactivation returns to naive levels. Conversely, Kv3.4 currents at 2–6 weeks post-SCI are downregulated and remain slow-inactivating. Immunohistochemistry indicated that downregulation mainly resulted from decreased surface expression of the Kv3.4 channel, as whole-DRG-protein and single-cell mRNA transcript levels did not change. Furthermore, consistent with Kv3.4 channel dysregulation, PKC activation failed to shorten the AP duration of small-diameter DRG neurons. Finally, re-expressing synthetic Kv3.4 currents under dynamic clamp conditions dampened repetitive spiking in the neurons from SCI rats. These results suggest a novel peripheral mechanism of post-SCI pain sensitization implicating Kv3.4 channel dysregulation and potential Kv3.4-based therapeutic interventions. PMID:25609640

  13. Sox5 controls dorsal progenitor and interneuron specification in the spinal cord.

    PubMed

    Quiroga, Alejandra C; Stolt, C Claus; Diez del Corral, Ruth; Dimitrov, Spas; Pérez-Alcalá, Siro; Sock, Elisabeth; Barbas, Julio A; Wegner, Michael; Morales, Aixa V

    2015-05-01

    The basic organization of somatosensory circuits in the spinal cord is already setup during the initial patterning of the dorsal neural tube. Extrinsic signals, such as Wnt and TGF-β pathways, activate combinatorial codes of transcription factors that are responsible for generating a pattern of discrete domains of dorsal progenitors (dp). These progenitors will give rise to distinct dorsal interneurons (dI). The Wnt/ βcatenin signaling pathway controls specification of dp/dI1-3 progenitors and interneurons. According to the current model in the field, Wnt/βcatenin activity seems to act in a graded fashion in the spinal cord, as different relative levels determine the identity of adjacent progenitors. However, it is not clear how this activity gradient is controlled and how the identities of dI1-3 are differentially regulated by Wnt signalling. We have determined that two SoxD transcription factors, Sox5 and Sox6, are expressed in restricted domains of dorsal progenitors in the neural tube. Using gain- and loss-of function approaches in chicken embryos, we have established that Sox5 controls cell fate specification of dp2 and dp3 progenitors and, as a result, controls the correct number of the corresponding dorsal interneurons (dI2 and dI3). Furthermore, Sox5 exerts its function by restricting dorsally Wnt signaling activity via direct transcriptional induction of the negative Wnt pathway regulator Axin2. By that way, Sox5 acts as a Wnt pathway modulator that contributes to sharpen the dorsal gradient of Wnt/βcatenin activity to control the distinction of two functionally distinct types of interneurons, dI2 and dI3 involved in the somatosensory relay. PMID:25363628

  14. Plasticity and Recovery After Dorsal Column Spinal Cord Injury in Nonhuman Primates.

    PubMed

    Reed, Jamie L; Liao, Chia-Chi; Qi, Hui-Xin; Kaas, Jon H

    2016-01-01

    Here, we review recent work on plasticity and recovery after dorsal column spinal cord injury in nonhuman primates. Plasticity in the adult central nervous system has been established and studied for the past several decades; however, capacities and limits of plasticity are still under investigation. Studies of plasticity include assessing multiple measures before and after injury in animal models. Such studies are particularly important for improving recovery after injury in patients. In summarizing work by our research team and others, we suggest how the findings from plasticity studies in nonhuman primate models may affect therapeutic interventions for conditions involving sensory loss due to spinal cord injury. PMID:27578996

  15. Plasticity and Recovery After Dorsal Column Spinal Cord Injury in Nonhuman Primates

    PubMed Central

    Reed, Jamie L.; Liao, Chia-Chi; Qi, Hui-Xin; Kaas, Jon H.

    2016-01-01

    Here, we review recent work on plasticity and recovery after dorsal column spinal cord injury in nonhuman primates. Plasticity in the adult central nervous system has been established and studied for the past several decades; however, capacities and limits of plasticity are still under investigation. Studies of plasticity include assessing multiple measures before and after injury in animal models. Such studies are particularly important for improving recovery after injury in patients. In summarizing work by our research team and others, we suggest how the findings from plasticity studies in nonhuman primate models may affect therapeutic interventions for conditions involving sensory loss due to spinal cord injury. PMID:27578996

  16. Frequency Mapping of Rat Spinal Cord at 7T

    NASA Astrophysics Data System (ADS)

    Chen, Evan; Rauscher, Alexander; Kozlowski, Piotr; Yung, Andrew

    2012-10-01

    The spinal cord is an integral part of the nervous system responsible for sensory, motor, and reflex control crucial to all bodily function. Due to its non-invasive nature, MRI is well matched for characterizing and imaging of spinal cord, and is used extensively for clinical applications. Recent developments in magnetic resonance imaging (MRI) at high field (7T) using phase represents a new approach of characterizing spinal cord myelin. Theory suggests that microstructure differences in myelinated white matter (WM) and non-myelinated gray matter (GM) affect MR phase, measurable frequency shifts. Data from pilot experiments using a multi-gradient echo (MGE) sequence to image rat spinal cords placed parallel to main magnetic field B0 has shown frequency shifts between not only between WM and GM, but also between specific WM tracts of the dorsal column, including the fasciculus gracilis, fasciculus cuneatus, and corticospinal tract. Using MGE, frequency maps at multiple echo times (TE) between 4ms and 22ms show a non-linear relationship between WM frequency, contrary to what was previously expected. These results demonstrate the effectiveness of MGE in revealing new information about spinal cord tissue microstructure, and lays important groundwork for in-vivo and human studies.

  17. Evaluation of optimal electrode configurations for epidural spinal cord stimulation in cervical spinal cord injured rats

    PubMed Central

    Alam, Monzurul; Garcia-Alias, Guillermo; Shah, Prithvi K.; Gerasimenko, Yury; Zhong, Hui; Roy, Roland R.; Edgerton, V. Reggie

    2015-01-01

    Background Epidural spinal cord stimulation is a promising technique for modulating the level of excitability and reactivation of dormant spinal neuronal circuits after spinal cord injury (SCI). We examined the ability of chronically implanted epidural stimulation electrodes within the cervical spinal cord to (1) directly elicit spinal motor evoked potentials (sMEPs) in forelimb muscles and (2) determine whether these sMEPs can serve as a biomarker of forelimb motor function after SCI. New method We implanted EMG electrodes in forelimb muscles and epidural stimulation electrodes at C6 and C8 in adult rats. After recovering from a dorsal funiculi crush (C4), rats were tested with different stimulation configurations and current intensities to elicit sMEPs and determined forelimb grip strength. Results: sMEPs were evoked in all muscles tested and their characteristics were dependent on electrode configurations and current intensities. C6(−) stimulation elicited more robust sMEPs than stimulation at C8(−). Stimulating C6 and C8 simultaneously produced better muscle recruitment and higher grip strengths than stimulation at one site. Comparison with existing method(s) Classical method to select the most optimal stimulation configuration is to empirically test each combination individually for every subject and relate to functional improvements. This approach is impractical, requiring extensively long experimental time to determine the more effective stimulation parameters. Our proposed method is fast and physiologically sound. Conclusions Results suggest that sMEPs from forelimb muscles can be useful biomarkers for identifying optimal parameters for epidural stimulation of the cervical spinal cord after SCI. PMID:25791014

  18. Neuron-astrocyte interactions in spinal cord dorsal horn in neuropathic pain development and docosahexaenoic acid therapy.

    PubMed

    Manzhulo, Igor V; Ogurtsova, Olga S; Kipryushina, Yuliya O; Latyshev, Nikolay A; Kasyanov, Sergey P; Dyuizen, Inessa V; Tyrtyshnaia, Anna A

    2016-09-15

    The analgesic activity of docosahexaenoic acid (DHA, 22:6 n-3) was studied using a chronic constriction injury (CCI) rat model. Animals were subcutaneously injected with DHA emulsion at a dose of 4.5mg/kg (125mМ/kg) daily during 2weeks after surgery. We characterized the dynamics of GFAP-positive astrocyte, substance P (SP) and nNOS-positive neurons activity in the spinal cord dorsal horn (SCDH) superficial lamina. We found that DHA treatment decrease the intensity and duration of neurogenic pain syndrome, results in earlier stabilization of weight distribution, prevents the cold allodynia and dystrophic changings in denervated limb tissue. DHA treatment reduced the reactive astrocyte number, decrease SP-immunopositive fibers and nNOS-positive neurons number in the SCDH in neuropathic pain. PMID:27609281

  19. Spino-olivary projections in the rat are anatomically separate from postsynaptic dorsal column projections.

    PubMed

    Flavell, Charlotte R; Cerminara, Nadia L; Apps, Richard; Lumb, Bridget M

    2014-06-15

    The gracile nucleus (GN) and lateral part of rostral dorsal accessory olive (rDAO) are important relays for indirect, postsynaptic dorsal column, and direct ascending pathways, respectively, that terminate as climbing fibers in the "hindlimb-receiving" parts of the C1 and C3 zones in the cerebellar cortex. While the spinal cells of origin of that project to GN and rDAO are from largely separate territories in the spinal cord, previous studies have indicated that there could be an area of overlap between these two populations in the medial dorsal horn. Given the access of these two ascending tracts to sensory (thalamic) versus sensorimotor (precerebellar) pathways, the present study therefore addresses the important question of whether or not individual neurons have the potential to contribute axons to both ascending pathways. A double-fluorescent tracer strategy was used in rats (red Retrobeads and Fluoro-Ruby or green Retrobeads and Fluoro-Emerald) to map the spatial distribution of cells of origin of the two projections in the lumbar spinal cord. The two pathways were found to receive input from almost entirely separate territories within the lumbar cord (levels L3-L5). GN predominantly receives input from lamina IV, while rDAO receives its input from three cell populations: medial laminae V-VI, lateral lamina V, and medial laminae VII-VIII. Cells that had axons that branched to supply both GN and rDAO represented only about 1% of either single-labeled cell population. Overall, the findings therefore suggest functional independence of the two ascending pathways. PMID:24357064

  20. Spinal Interneurons and Forelimb Plasticity after Incomplete Cervical Spinal Cord Injury in Adult Rats

    PubMed Central

    Rombola, Angela M.; Rousseau, Celeste A.; Mercier, Lynne M.; Fitzpatrick, Garrett M.; Reier, Paul J.; Fuller, David D.; Lane, Michael A.

    2015-01-01

    Abstract Cervical spinal cord injury (cSCI) disrupts bulbospinal projections to motoneurons controlling the upper limbs, resulting in significant functional impairments. Ongoing clinical and experimental research has revealed several lines of evidence for functional neuroplasticity and recovery of upper extremity function after SCI. The underlying neural substrates, however, have not been thoroughly characterized. The goals of the present study were to map the intraspinal motor circuitry associated with a defined upper extremity muscle, and evaluate chronic changes in the distribution of this circuit following incomplete cSCI. Injured animals received a high cervical (C2) lateral hemisection (Hx), which compromises supraspinal input to ipsilateral spinal motoneurons controlling the upper extremities (forelimb) in the adult rat. A battery of behavioral tests was used to characterize the time course and extent of forelimb motor recovery over a 16 week period post-injury. A retrograde transneuronal tracer – pseudorabies virus – was used to define the motor and pre-motor circuitry controlling the extensor carpi radialis longus (ECRL) muscle in spinal intact and injured animals. In the spinal intact rat, labeling was observed unilaterally within the ECRL motoneuron pool and within spinal interneurons bilaterally distributed within the dorsal horn and intermediate gray matter. No changes in labeling were observed 16 weeks post-injury, despite a moderate degree of recovery of forelimb motor function. These results suggest that recovery of the forelimb function assessed following C2Hx injury does not involve recruitment of new interneurons into the ipsilateral ECRL motor pathway. However, the functional significance of these existing interneurons to motor recovery requires further exploration. PMID:25625912

  1. Periaqueductal grey cyclooxygenase-dependent facilitation of C-nociceptive drive and encoding in dorsal horn neurons in the rat

    PubMed Central

    Leith, J Lianne; Wilson, Alex W; You, Hao-Jun; Lumb, Bridget M; Donaldson, Lucy F

    2014-01-01

    Abstract The experience of pain is strongly affected by descending control systems originating in the brainstem ventrolateral periaqueductal grey (VL-PAG), which control the spinal processing of nociceptive information. A- and C-fibre nociceptors detect noxious stimulation, and have distinct and independent contributions to both the perception of pain quality (fast and slow pain, respectively) and the development of chronic pain. Evidence suggests a separation in the central processing of information arising from A- vs. C-nociceptors; for example, inhibition of the cyclooxygenase-1 (COX-1)–prostaglandin system within the VL-PAG alters spinal nociceptive reflexes evoked by C-nociceptor input in vivo via descending pathways, leaving A-nociceptor-evoked reflexes largely unaffected. As the spinal neuronal mechanisms underlying these different responses remain unknown, we determined the effect of inhibition of VL-PAG COX-1 on dorsal horn wide dynamic-range neurons evoked by C- vs. A-nociceptor activation. Inhibition of VL-PAG COX-1 in anaesthetised rats increased firing thresholds of lamina IV–V wide dynamic-range dorsal horn neurons in response to both A- and C-nociceptor stimulation. Importantly, wide dynamic-range dorsal horn neurons continued to faithfully encode A-nociceptive information, even after VL-PAG COX-1 inhibition, whereas the encoding of C-nociceptor information by wide dynamic-range spinal neurons was significantly disrupted. Dorsal horn neurons with stronger C-nociceptor input were affected by COX-1 inhibition to a greater extent than those with weak C-fibre input. These data show that the gain and contrast of C-nociceptive information processed in individual wide dynamic-range dorsal horn neurons is modulated by prostanergic descending control mechanisms in the VL-PAG. PMID:25239460

  2. Interferon-gamma potentiates NMDA receptor signaling in spinal dorsal horn neurons via microglia–neuron interaction

    PubMed Central

    Sonekatsu, Mayumi; Yamanaka, Manabu; Nishio, Naoko; Tsutsui, Shunji; Yamada, Hiroshi; Yoshida, Munehito; Nakatsuka, Terumasa

    2016-01-01

    Background Glia–neuron interactions play an important role in the development of neuropathic pain. Expression of the pro-inflammatory cytokne →cytokine Interferon-gamma (IFNγ) is upregulated in the dorsal horn after peripheral nerve injury, and intrathecal IFNγ administration induces mechanical allodynia in rats. A growing body of evidence suggests that IFNγ might be involved in the mechanisms of neuropathic pain, but its effects on the spinal dorsal horn are unclear. We performed blind whole-cell patch-clamp recording to investigate the effect of IFNγ on postsynaptic glutamate-induced currents in the substantia gelatinosa neurons of spinal cord slices from adult male rats. Results IFNγ perfusion significantly enhanced the amplitude of NMDA-induced inward currents in substantia gelatinosa neurons, but did not affect AMPA-induced currents. The facilitation of NMDA-induced current by IFNγ was inhibited by bath application of an IFNγ receptor-selective antagonist. Adding the Janus activated kinase inhibitor tofacitinib to the pipette solution did not affect the IFNγ-induced facilitation of NMDA-induced currents. However, the facilitatory effect of IFNγ on NMDA-induced currents was inhibited by perfusion of the microglial inhibitor minocycline. These results suggest that IFNγ binds the microglial IFNγ receptor and enhances NMDA receptor activity in substantia gelatinosa neurons. Next, to identify the effector of signal transmission from microglia to dorsal horn neurons, we added an inhibitor of G proteins, GDP-β-S, to the pipette solution. In a GDP-β-S–containing pipette solution, IFNγ-induced potentiation of the NMDA current was significantly suppressed after 30 min. In addition, IFNγ-induced potentiation of NMDA currents was blocked by application of a selective antagonist of CCR2, and its ligand CCL2 increased NMDA-induced currents. Conclusion Our findings suggest that IFNγ enhance the amplitude of NMDA-induced inward currents in substantia

  3. Morphological, biophysical and synaptic properties of glutamatergic neurons of the mouse spinal dorsal horn

    PubMed Central

    Punnakkal, Pradeep; Schoultz, Carolin; Haenraets, Karen; Wildner, Hendrik; Zeilhofer, Hanns Ulrich

    2014-01-01

    Interneurons of the spinal dorsal horn are central to somatosensory and nociceptive processing. A mechanistic understanding of their function depends on profound knowledge of their intrinsic properties and their integration into dorsal horn circuits. Here, we have used BAC transgenic mice expressing enhanced green fluorescent protein (eGFP) under the control of the vesicular glutamate transporter (vGluT2) gene (vGluT2::eGFP mice) to perform a detailed electrophysiological and morphological characterisation of excitatory dorsal horn neurons, and to compare their properties to those of GABAergic (Gad67::eGFP tagged) and glycinergic (GlyT2::eGFP tagged) neurons. vGluT2::eGFP was detected in about one-third of all excitatory dorsal horn neurons and, as demonstrated by the co-expression of vGluT2::eGFP with different markers of subtypes of glutamatergic neurons, probably labelled a representative fraction of these neurons. Three types of dendritic tree morphologies (vertical, central, and radial), but no islet cell-type morphology, were identified in vGluT2::eGFP neurons. vGluT2::eGFP neurons had more depolarised action potential thresholds and longer action potential durations than inhibitory neurons, while no significant differences were found for the resting membrane potential, input resistance, cell capacitance and after-hyperpolarisation. Delayed firing and single action potential firing were the single most prevalent firing patterns in vGluT2::eGFP neurons of the superficial and deep dorsal horn, respectively. By contrast, tonic firing prevailed in inhibitory interneurons of the dorsal horn. Capsaicin-induced synaptic inputs were detected in about half of the excitatory and inhibitory neurons, and occurred more frequently in superficial than in deep dorsal horn neurons. Primary afferent-evoked (polysynaptic) inhibitory inputs were found in the majority of glutamatergic and glycinergic neurons, but only in less than half of the GABAergic population. Excitatory

  4. Enhanced Functional Recovery in MRL/MpJ Mice after Spinal Cord Dorsal Hemisection

    PubMed Central

    Thuret, Sandrine; Thallmair, Michaela; Horky, Laura L.; Gage, Fred H.

    2012-01-01

    Adult MRL/MpJ mice have been shown to possess unique regeneration capabilities. They are able to heal an ear-punched hole or an injured heart with normal tissue architecture and without scar formation. Here we present functional and histological evidence for enhanced recovery following spinal cord injury (SCI) in MRL/MpJ mice. A control group (C57BL/6 mice) and MRL/MpJ mice underwent a dorsal hemisection at T9 (thoracic vertebra 9). Our data show that MRL/MpJ mice recovered motor function significantly faster and more completely. We observed enhanced regeneration of the corticospinal tract (CST). Furthermore, we observed a reduced astrocytic response and fewer micro-cavities at the injury site, which appear to create a more growth-permissive environment for the injured axons. Our data suggest that the reduced astrocytic response is in part due to a lower lesion-induced increase of cell proliferation post-SCI, and a reduced astrocytic differentiation of the proliferating cells. Interestingly, we also found an increased number of proliferating microglia, which could be involved in the MRL/MpJ spinal cord repair mechanisms. Finally, to evaluate the molecular basis of faster spinal cord repair, we examined the difference in gene expression changes in MRL/MpJ and C57BL/6 mice after SCI. Our microarray data support our histological findings and reveal a transcriptional profile associated with a more efficient spinal cord repair in MRL/MpJ mice. PMID:22348029

  5. Electrical maturation of spinal neurons in the human fetus: comparison of ventral and dorsal horn.

    PubMed

    Tadros, M A; Lim, R; Hughes, D I; Brichta, A M; Callister, R J

    2015-11-01

    The spinal cord is critical for modifying and relaying sensory information to, and motor commands from, higher centers in the central nervous system to initiate and maintain contextually relevant locomotor responses. Our understanding of how spinal sensorimotor circuits are established during in utero development is based largely on studies in rodents. In contrast, there is little functional data on the development of sensory and motor systems in humans. Here, we use patch-clamp electrophysiology to examine the development of neuronal excitability in human fetal spinal cords (10-18 wk gestation; WG). Transverse spinal cord slices (300 μm thick) were prepared, and recordings were made, from visualized neurons in either the ventral (VH) or dorsal horn (DH) at 32°C. Action potentials (APs) could be elicited in VH neurons throughout the period examined, but only after 16 WG in DH neurons. At this age, VH neurons discharged multiple APs, whereas most DH neurons discharged single APs. In addition, at 16-18 WG, VH neurons also displayed larger AP and after-hyperpolarization amplitudes than DH neurons. Between 10 and 18 WG, the intrinsic properties of VH neurons changed markedly, with input resistance decreasing and AP and after-hyperpolarization amplitudes increasing. These findings are consistent with the hypothesis that VH motor circuitry matures more rapidly than the DH circuits that are involved in processing tactile and nociceptive information. PMID:26334015

  6. Experimental autoimmune neuritis induces differential microglia activation in the rat spinal cord.

    PubMed

    Beiter, Thomas; Artelt, Matthias R; Trautmann, Katrin; Schluesener, Hermann J

    2005-03-01

    The reactive spatial and temporal activation pattern of parenchymal spinal cord microglia was analyzed in rat experimental autoimmune neuritis (EAN). We observed a differential activation of spinal cord microglial cells. A significant increase in ED1(+) microglia predominantly located in the dorsal horn grey matter of lumbar and thoracic spinal cord levels was observed on Day 12. As revealed by morphological criteria and by staining with further activation markers [allograft inflammatory factor 1 (AIF-1), EMAPII, OX6, P2X(4)R], reactive microglia did not reach a macrophage-like state of full activation. On Day 12, a significant proliferative response could be observed, affecting all spinal cord areas and including ED1(+) microglial cells and a wide range of putative progenitor cells. Thus, in rat EAN, a reactive localized and distinct microglial activation correlating with a generalized proliferative response could be observed. PMID:15710454

  7. Pronociceptive and Antinociceptive Effects of Buprenorphine in the Spinal Cord Dorsal Horn Cover a Dose Range of Four Orders of Magnitude

    PubMed Central

    Gerhold, Katharina J.; Drdla-Schutting, Ruth; Honsek, Silke D.; Forsthuber, Liesbeth

    2015-01-01

    Due to its distinct pharmacological profile and lower incidence of adverse events compared with other opioids, buprenorphine is considered a safe option for pain and substitution therapy. However, despite its wide clinical use, little is known about the synaptic effects of buprenorphine in nociceptive pathways. Here, we demonstrate dose-dependent, bimodal effects of buprenorphine on transmission at C-fiber synapses in rat spinal cord dorsal horn in vivo. At an analgesically active dose of 1500 μg·kg−1, buprenorphine reduced the strength of spinal C-fiber synapses. This depression required activation of spinal opioid receptors, putatively μ1-opioid receptors, as indicated by its sensitivity to spinal naloxone and to the selective μ1-opioid receptor antagonist naloxonazine. In contrast, a 15,000-fold lower dose of buprenorphine (0.1 μg·kg−1), which caused thermal and mechanical hyperalgesia in behaving animals, induced an enhancement of transmission at spinal C-fiber synapses. The ultra-low-dose buprenorphine-induced synaptic facilitation was mediated by supraspinal naloxonazine-insensitive, but CTOP-sensitive μ-opioid receptors, descending serotonergic pathways, and activation of spinal glial cells. Selective inhibition of spinal 5-hydroxytryptamine-2 receptors (5-HT2Rs), putatively located on spinal astrocytes, abolished both the induction of synaptic facilitation and the hyperalgesia elicited by ultra-low-dose buprenorphine. Our study revealed that buprenorphine mediates its modulatory effects on transmission at spinal C-fiber synapses by dose dependently acting on distinct μ-opioid receptor subtypes located at different levels of the neuraxis. PMID:26134641

  8. Reactive Oxygen Species Donors Increase the Responsiveness of Dorsal Horn Neurons and Induce Mechanical Hyperalgesia in Rats

    PubMed Central

    Kim, Hee Young; Lee, Inhyung; Chun, Sang Woo; Kim, Hee Kee

    2015-01-01

    Our previous studies suggest that reactive oxygen species (ROS) scavengers have analgesic effect on neuropathic pain through spinal mechanisms in the rat. The studies suggest that superoxide in spinal cord is one of important mediators of persistent pain. To test the hypothesis that increase of superoxide-derived intermediates leads to central sensitization and pain, the effects of an intrathecal injection of chemical ROS donors releasing either OH∙, OCl−, or H2O2 were examined on pain behaviors. Following treatment with t-BOOH (OH∙ donor), dorsal horn neuron responses to mechanical stimuli in normal rats and the changes of neuronal excitability were explored on substantia gelatinosa (SG) neurons using whole-cell patch clamping recordings. Intrathecal administration of t-BOOH or NaOCl (OCl− donor), but not H2O2, significantly decreased mechanical thresholds of hind paws. The responses of wide dynamic range neurons to mechanical stimuli increased after a local application of t-BOOH. The t-BOOH increased the frequency and the amplitude of excitatory postsynaptic potentials, depolarized membrane potential in SG neurons, and increased the frequency of action potentials evoked by depolarizing current pulses. These results suggest that elevated ROS, especially OH∙, in the spinal cord sensitized dorsal horn neurons and produced hyperalgesia in normal rats. PMID:26457204

  9. 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

  10. Intravenous administration of lidocaine directly acts on spinal dorsal horn and produces analgesic effect: An in vivo patch-clamp analysis.

    PubMed

    Kurabe, Miyuki; Furue, Hidemasa; Kohno, Tatsuro

    2016-01-01

    Intravenous lidocaine administration produces an analgesic effect in various pain states, such as neuropathic and acute pain, although the underlying mechanisms remains unclear. Here, we hypothesized that intravenous lidocaine acts on spinal cord neurons and induces analgesia in acute pain. We therefore examined the action of intravenous lidocaine in the spinal cord using the in vivo patch-clamp technique. We first investigated the effects of intravenous lidocaine using behavioural measures in rats. We then performed in vivo patch-clamp recording from spinal substantia gelatinosa (SG) neurons. Intravenous lidocaine had a dose-dependent analgesic effect on the withdrawal response to noxious mechanical stimuli. In the electrophysiological experiments, intravenous lidocaine inhibited the excitatory postsynaptic currents (EPSCs) evoked by noxious pinch stimuli. Intravenous lidocaine also decreased the frequency, but did not change the amplitude, of both spontaneous and miniature EPSCs. However, it did not affect inhibitory postsynaptic currents. Furthermore, intravenous lidocaine induced outward currents in SG neurons. Intravenous lidocaine inhibits glutamate release from presynaptic terminals in spinal SG neurons. Concomitantly, it hyperpolarizes postsynaptic neurons by shifting the membrane potential. This decrease in the excitability of spinal dorsal horn neurons may be a possible mechanism for the analgesic action of intravenous lidocaine in acute pain. PMID:27188335

  11. Intravenous administration of lidocaine directly acts on spinal dorsal horn and produces analgesic effect: An in vivo patch-clamp analysis

    PubMed Central

    Kurabe, Miyuki; Furue, Hidemasa; Kohno, Tatsuro

    2016-01-01

    Intravenous lidocaine administration produces an analgesic effect in various pain states, such as neuropathic and acute pain, although the underlying mechanisms remains unclear. Here, we hypothesized that intravenous lidocaine acts on spinal cord neurons and induces analgesia in acute pain. We therefore examined the action of intravenous lidocaine in the spinal cord using the in vivo patch-clamp technique. We first investigated the effects of intravenous lidocaine using behavioural measures in rats. We then performed in vivo patch-clamp recording from spinal substantia gelatinosa (SG) neurons. Intravenous lidocaine had a dose-dependent analgesic effect on the withdrawal response to noxious mechanical stimuli. In the electrophysiological experiments, intravenous lidocaine inhibited the excitatory postsynaptic currents (EPSCs) evoked by noxious pinch stimuli. Intravenous lidocaine also decreased the frequency, but did not change the amplitude, of both spontaneous and miniature EPSCs. However, it did not affect inhibitory postsynaptic currents. Furthermore, intravenous lidocaine induced outward currents in SG neurons. Intravenous lidocaine inhibits glutamate release from presynaptic terminals in spinal SG neurons. Concomitantly, it hyperpolarizes postsynaptic neurons by shifting the membrane potential. This decrease in the excitability of spinal dorsal horn neurons may be a possible mechanism for the analgesic action of intravenous lidocaine in acute pain. PMID:27188335

  12. Localization of cyclooxygenase-2 and prostaglandin E2 receptor EP3 in the rat lumbar spinal cord.

    PubMed

    Beiche, F; Klein, T; Nüsing, R; Neuhuber, W; Goppelt-Struebe, M

    1998-08-14

    Cyclooxygenase-2 (COX-2) is now considered to be the major constitutively expressed COX isozyme in the central nervous system. The present immunocytochemical study details localization of COX-2 immunoreactivity in rat spinal cord along with the expression of prostaglandin E2 receptor subtype EP3. Prominent COX-2 staining was observed in the nuclear envelope of neurons throughout the spinal cord, especially in the superficial dorsal horn laminae and motoneurons of lamina IX, as well as in glial cells of the white matter. Expression of EP3 receptor was strictly confined to afferent terminal areas in the superficial dorsal horns. PMID:9726822

  13. Critical evaluation of the expression of gastrin-releasing peptide in dorsal root ganglia and spinal cord

    PubMed Central

    Barry, Devin M; Li, Hui; Liu, Xian-Yu; Shen, Kai-Feng; Liu, Xue-Ting; Wu, Zhen-Yu; Munanairi, Admire; Chen, Xiao-Jun; Yin, Jun; Sun, Yan-Gang; Li, Yun-Qing

    2016-01-01

    There are substantial disagreements about the expression of gastrin-releasing peptide (GRP) in sensory neurons and whether GRP antibody cross-reacts with substance P (SP). These concerns necessitate a critical revaluation of GRP expression using additional approaches. Here, we show that a widely used GRP antibody specifically recognizes GRP but not SP. In the spinal cord of mice lacking SP (Tac1 KO), the expression of not only GRP but also other peptides, notably neuropeptide Y (NPY), is significantly diminished. We detected Grp mRNA in dorsal root ganglias using reverse transcription polymerase chain reaction, in situ hybridization and RNA-seq. We demonstrated that Grp mRNA and protein are upregulated in dorsal root ganglias, but not in the spinal cord, of mice with chronic itch. Few GRP+ immunostaining signals were detected in spinal sections following dorsal rhizotomy and GRP+ cell bodies were not detected in dissociated dorsal horn neurons. Ultrastructural analysis further shows that substantially more GRPergic fibers form synaptic contacts with gastrin releasing peptide receptor-positive (GRPR+) neurons than SPergic fibers. Our comprehensive study demonstrates that a majority of GRPergic fibers are of primary afferent origin. A number of factors such as low copy number of Grp transcripts, small percentage of cells expressing Grp, and the use of an eGFP GENSAT transgenic as a surrogate for GRP protein have contributed to the controversy. Optimization of experimental procedures facilitates the specific detection of GRP expression in dorsal root ganglia neurons. PMID:27068287

  14. Development of regional specificity of spinal and medullary dorsal horn neurons

    PubMed Central

    Xie, Yu-Feng; Jiang, Xing-Hong; Sessle, Barry J; Yu, Xian-Min

    2016-01-01

    Extensive studies have focused on the development and regionalization of neurons in the central nervous system (CNS). Many genes, which play crucial roles in the development of CNS neurons, have been identified. By using the technique “direct reprogramming”, neurons can be produced from multiple cell sources such as fibroblasts. However, understanding the region-specific regulation of neurons in the CNS is still one of the biggest challenges in the research field of neuroscience. Neurons located in the trigeminal subnucleus caudalis (Vc) and in the spinal dorsal horn (SDH) play crucial roles in pain and sensorimotor functions in the orofacial and other somatic body regions, respectively. Anatomically, Vc represents the most caudal component of the trigeminal system, and is contiguous with SDH. This review is focused on recent data dealing with the regional specificity involved in the development of neurons in Vc and SDH. PMID:26981202

  15. Delta opioid receptors presynaptically regulate cutaneous mechanosensory neuron input to the spinal cord dorsal horn.

    PubMed

    Bardoni, Rita; Tawfik, Vivianne L; Wang, Dong; François, Amaury; Solorzano, Carlos; Shuster, Scott A; Choudhury, Papiya; Betelli, Chiara; Cassidy, Colleen; Smith, Kristen; de Nooij, Joriene C; Mennicken, Françoise; O'Donnell, Dajan; Kieffer, Brigitte L; Woodbury, C Jeffrey; Basbaum, Allan I; MacDermott, Amy B; Scherrer, Grégory

    2014-03-19

    Cutaneous mechanosensory neurons detect mechanical stimuli that generate touch and pain sensation. Although opioids are generally associated only with the control of pain, here we report that the opioid system in fact broadly regulates cutaneous mechanosensation, including touch. This function is predominantly subserved by the delta opioid receptor (DOR), which is expressed by myelinated mechanoreceptors that form Meissner corpuscles, Merkel cell-neurite complexes, and circumferential hair follicle endings. These afferents also include a small population of CGRP-expressing myelinated nociceptors that we now identify as the somatosensory neurons that coexpress mu and delta opioid receptors. We further demonstrate that DOR activation at the central terminals of myelinated mechanoreceptors depresses synaptic input to the spinal dorsal horn, via the inhibition of voltage-gated calcium channels. Collectively our results uncover a molecular mechanism by which opioids modulate cutaneous mechanosensation and provide a rationale for targeting DOR to alleviate injury-induced mechanical hypersensitivity. PMID:24583022

  16. Delta Opioid Receptors Presynaptically Regulate Cutaneous Mechanosensory Neuron Input to the Spinal Cord Dorsal Horn

    PubMed Central

    Bardoni, Rita; Tawfik, Vivianne L.; Wang, Dong; François, Amaury; Solorzano, Carlos; Shuster, Scott A.; Choudhury, Papiya; Betelli, Chiara; Cassidy, Colleen; Smith, Kristen; de Nooij, Joriene C.; Mennicken, Françoise; O’Donnell, Dajan; Kieffer, Brigitte L.; Woodbury, C. Jeffrey; Basbaum, Allan I.; MacDermott, Amy B.; Scherrer, Grégory

    2014-01-01

    SUMMARY Cutaneous mechanosensory neurons detect mechanical stimuli that generate touch and pain sensation. Although opioids are generally associated only with the control of pain, here we report that the opioid system in fact broadly regulates cutaneous mechanosensation, including touch. This function is predominantly subserved by the delta opioid receptor (DOR), which is expressed by myelinated mechanoreceptors that form Meissner corpuscles, Merkel cell-neurite complexes, and circumferential hair follicle endings. These afferents also include a small population of CGRP-expressing myelinated nociceptors that we now identify as the somatosensory neurons that coexpress mu and delta opioid receptors. We further demonstrate that DOR activation at the central terminals of myelinated mechanoreceptors depresses synaptic input to the spinal dorsal horn, via the inhibition of voltage-gated calcium channels. Collectively our results uncover a molecular mechanism by which opioids modulate cutaneous mechanosensation and provide a rationale for targeting DOR to alleviate injury-induced mechanical hypersensitivity. PMID:24583022

  17. Intraneuronal angiotensinergic system in rat and human dorsal root ganglia

    PubMed Central

    Patil, Jaspal; Schwab, Alexander; Nussberger, Juerg; Schaffner, Thomas; Saavedra, Juan M.; Imboden, Hans

    2010-01-01

    To elucidate the local formation of angiotensin II (Ang II) in the neurons of sensory dorsal root ganglia (DRG), we studied the expression of angiotensinogen (Ang-N)-, renin-, angiotensin converting enzyme (ACE)- and cathepsin D-mRNA, and the presence of protein renin, Ang II, Substance P and calcitonin gene-related peptide (CGRP) in the rat and human thoracic DRG. Quantitative real time PCR (qRT-PCR) studies revealed that rat DRG expressed substantial amounts of Ang-N- and ACE mRNA, while renin mRNA as well as the protein renin were untraceable. Cathepsin D-mRNA and cathepsin D-protein were detected in the rat DRG indicating the possibility of existence of pathways alternative to renin for Ang I formation. Angiotensin peptides were successfully detected with high performance liquid chromatography and radioimmunoassay in human DRG extracts. In situ hybridization in rat DRG confirmed additionally expression of Ang-N mRNA in the cytoplasm of numerous neurons. Intracellular Ang II staining could be shown in number of neurons and their processes in both the rat and human DRG. Interestingly we observed neuronal processes with angiotensinergic synapses en passant, colocalized with synaptophysin, within the DRG. In the DRG, we also identified by qRT-PCR, expression of Ang II receptor AT1A and AT2-mRNA while AT1B-mRNA was not traceable. In some neurons Substance P and CGRP were found colocalized with Ang II. The intracellular localization and colocalization of Ang II with Substance P and CGRP in the DRG neurons may indicate a participation and function of Ang II in the regulation of nociception. In conclusion, these results suggest that Ang II may be produced locally in the neurons of rat and human DRG and act as a neurotransmitter. PMID:20346377

  18. Selective axonal and glial distribution of monoacylglycerol lipase immunoreactivity in the superficial spinal dorsal horn of rodents.

    PubMed

    Dócs, Klaudia; Hegyi, Zoltán; Holló, Krisztina; Kis, Gréta; Hegedűs, Krisztina; Antal, Miklós

    2015-09-01

    The importance of 2-AG-mediated endogenous cannabinoid signaling in spinal pain control has recently been well substantiated. Although the degradation of 2-AG seems to be essential in cannabinoid-mediated spinal nociceptive information processing, no experimental data are available about the cellular distribution of monoacylglycerol lipase (MGL), the main degrading enzyme of 2-AG in the spinal dorsal horn. Thus, here we investigated the cellular distribution of MGL in laminae I-II of the spinal gray matter with immunocytochemical methods and revealed an abundant immunoreactivity for MGL in the rodent superficial spinal dorsal horn. We addressed the co-localization of MGL with markers of peptidergic and non-peptidergic primary afferents, axon terminals of putative glutamatergic and GABAergic spinal neurons, as well as astrocytic and microglial profiles, and we found that nearly 17 % of the peptidergic (immunoreactive for CGRP), a bit more than 10 % of the axon terminals of putative glutamatergic spinal neurons (immunoreactive for VGLUT2), and approximately 20 % of the astrocytic (immunoreactive for GFAP) profiles were immunolabeled for MGL. On the other hand, however, axon terminals of non-peptidergic (binding isolectin-B4) nociceptive primary afferents and putative inhibitory spinal neurons (immunoreactive for VGAT) as well as microglial (immunoreactive for CD11b) profiles showed negligible immunostaining for MGL. The results suggest that only nociceptive inputs arriving through a population of CGRP immunoreactive fibers are modulated by the spinal DGLα-MGL pathway. We also postulate that the DGLα-MGL signaling pathway may modulate spinal excitatory but not inhibitory neural circuits. PMID:24942136

  19. Inhibitory coupling between inhibitory interneurons in the spinal cord dorsal horn.

    PubMed

    Labrakakis, Charalampos; Lorenzo, Louis-Etienne; Bories, Cyril; Ribeiro-da-Silva, Alfredo; De Koninck, Yves

    2009-01-01

    Local inhibitory interneurons in the dorsal horn play an important role in the control of excitability at the segmental level and thus determine how nociceptive information is relayed to higher structures. Regulation of inhibitory interneuron activity may therefore have critical consequences on pain perception. Indeed, disinhibition of dorsal horn neuronal networks disrupts the balance between excitation and inhibition and is believed to be a key mechanism underlying different forms of pain hypersensitivity and chronic pain states. In this context, studying the source and the synaptic properties of the inhibitory inputs that the inhibitory interneurons receive is important in order to predict the impact of drug action at the network level. To address this, we studied inhibitory synaptic transmission in lamina II inhibitory interneurons identified under visual guidance in spinal slices taken from transgenic mice expressing enhanced green fluorescent protein (EGFP) under the control of the GAD promoter. The majority of these cells fired tonically to a long depolarizing current pulse. Monosynaptically evoked inhibitory postsynaptic currents (eIPSCs) in these cells were mediated by both GABAA and glycine receptors. Consistent with this, both GABAA and glycine receptor-mediated miniature IPSCs were recorded in all of the cells. These inhibitory inputs originated at least in part from local lamina II interneurons as verified by simultaneous recordings from pairs of EGFP+ cells. These synapses appeared to have low release probability and displayed potentiation and asynchronous release upon repeated activation. In summary, we report on a previously unexamined component of the dorsal horn circuitry that likely constitutes an essential element of the fine tuning of nociception. PMID:19432997

  20. Retronasal odor representations in the dorsal olfactory bulb of rats

    PubMed Central

    Gautam, Shree Hari; Verhagen, Justus V.

    2012-01-01

    Animals perceive their olfactory environment not only from odors originating in the external world (orthonasal route) but also from odors released in the oral cavity while eating food (retronasal route). Retronasal olfaction is crucial for the perception of food flavor in humans. However, little is known about the retronasal stimulus coding in the brain. The most basic question is if and how route affects the odor representations at the level of the olfactory bulb (OB), where odor quality codes originate. We used optical calcium imaging of presynaptic dorsal OB responses to odorants in anesthetized rats to ask whether the rat OB could be activated retronasally, and how these responses compare to orthonasal responses under similar conditions. We further investigated the effects of specific odorant properties on orthoversus retronasal response patterns. We found that at a physiologically relevant flow rate retronasal odorants can effectively reach the olfactory receptor neurons, eliciting glomerular response patterns that grossly overlap with those of orthonasal responses, but differ from the orthonasal patterns in the response amplitude and temporal dynamics. Interestingly, such differences correlated well with specific odorant properties. Less volatile odorants yielded relatively smaller responses retronasally, but volatility did not affect relative temporal profiles. More polar odorants responded with relatively longer onset latency and time to peak retronasally, but polarity did not affect relative response magnitudes. These data provide insight into the early stages of retronasal stimulus coding and establish relationships between ortho- and retronasal odor representations in the rat OB. PMID:22674270

  1. The influence of protein-calorie malnutrition on the development of paranodal regions in spinal roots. A study with the OTAN method on rat.

    PubMed

    Nordborg, C

    1977-11-28

    During the early postnatal development of spinal roots in rats paranodal regions were often found, containing OTAN-positive inclusions in the Schwann cell cytoplasm. The presence of OTAN-positive paranodal regions showed variations in time, which were synchronous for ventral and dorsal roots. Dorsal roots, however, showed a more marked presence during development than ventral roots. Spinal roots of animals submitted to a 50% food restriction, were shown to contain more OTAN-positive paranodal regions than controls. This was true for ventral as well as dorsal roots. It is suggested that crowding of internodal segments could be one factor, determining the presence of paranodal, OTAN-positive material. PMID:414508

  2. Comparison of the Spinal Neuropathic Pain Induced by Intraspinal Injection of N-Methyl-D-Aspartate and Quisquate in Rats

    PubMed Central

    Choi, Seong-Soo; Min, Hong-Gi; Leem, Jeong-Gil

    2011-01-01

    Objective Excitatory amino acids play important roles in the development of secondary pathology following spinal cord injury (SCI). This study was designed to evaluate morphological changes in the dorsal horn of the spinal cord and assess profiles of pain behaviors following intraspinal injection of N-methyl-D-aspartate (NMDA) or quisqualate (QUIS) in rats. Methods Forty male Sprague-Dawley rats were randomized into three groups : a sham, and two experimental groups receiving injections of 125 mM NMDA or QUIS into their spinal dorsal horn. Following injection, hypersensitivity to cold and mechanical stimuli, and excessive grooming behaviors were assessed serially for four weeks. At the end of survival periods, morphological changes in the spinal cord were evaluated. Results Cold allodynia was developed in both the NMDA and QUIS groups, which was significantly higher in the QUIS group than in the NMDA group. The mechanical threshold for the ipsilateral hind paw in both QUIS and NMDA groups was significantly lower than that in the control group. The number of groomers was significantly higher in the NMDA group than in the QUIS group. The size of the neck region of the spinal dorsal horn, but not the superficial layer, was significantly smaller in the NMDA and QUIS groups than in the control group. Conclusion Intraspinal injection of NMDA or QUIS can be used as an excitotoxic model of SCI for further research on spinal neuropathic pain. PMID:22259688

  3. A novel device for studying weight supported, quadrupedal overground locomotion in spinal cord injured rats

    PubMed Central

    Hamlin, Marvin; Traughber, Terrance; Reinkensmeyer, David J.; de Leon, Ray D.

    2015-01-01

    Background Providing weight support facilitates locomotion in spinal cord injured animals. To control weight support, robotic systems have been developed for treadmill stepping and more recently for overground walking. New Method We developed a novel device, the body weight supported ambulatory rodent trainer (i.e. BART). It has a small pneumatic cylinder that moves along a linear track above the rat. When air is supplied to the cylinder, the rats are lifted as they perform overground walking. We tested the BART device in rats that received a moderate spinal cord contusion injury and in normal rats. Locomotor training with the BART device was not performed. Results All of the rats learned to walk in the BART device. In the contused rats, significantly greater paw dragging and dorsal stepping occurred in the hindlimbs compared to normal. Providing weight support significantly raised hip position and significantly reduced locomotor deficits. Hindlimb stepping was tightly coupled to forelimb stepping but only when the contused rats stepped without weight support. Three weeks after the contused rats received a complete spinal cord transection, significantly fewer hindlimb steps were performed. Comparison with Existing Methods Relative to rodent robotic systems, the BART device is a simpler system for studying overground locomotion. The BART device lacks sophisticated control and sensing capability, but it can be assembled relatively easily and cheaply. Conclusions These findings suggest that the BART device is a useful tool for assessing quadrupedal, overground locomotion which is a more natural form of locomotion relative to treadmill locomotion. PMID:25794460

  4. Remote Astrocytic and Microglial Activation Modulate Neuronal Hyperexcitability and Below-Level Neuropathic Pain after Spinal Injury in Rat

    PubMed Central

    Gwak, Young Seob; Hulsebosch, Claire E.

    2010-01-01

    In this study, we evaluated whether astrocytic and microglial activation mediates below-level neuropathic pain following spinal cord injury. Male Sprague-Dawley (225–250 g) rats were given low thoracic (T13) spinal transverse hemisection and behavioral, electrophysiological and immunohistochemical methods were used to examine the development and maintenance of below-level neuropathic pain. On post operation day 28, both hindlimbs showed significantly decreased paw withdrawal thresholds and thermal latencies as well as hyperexcitability of lumbar (L4-5) spinal wide dynamic range (WDR) neurons on both sides of spinal dorsal horn compared to sham controls (*p<0.05). Intrathecal treatment with propentofylline (PPF, 10 mM) for 7 consecutive days immediately after spinal injury attenuated the development of mechanical allodynia and thermal hyperalgesia in both hindlimbs in a dose related reduction compared to vehicle treatments (*p<0.05). Intrathecal treatment with single injections of PPF at 28 days after spinal injury, attenuated the existing mechanical allodynia and thermal hyperalgesia in both hindlimbs in a dose related reduction (*p<0.05). In electrophysiological studies, topical treatment of 10 mM PPF onto the spinal surface attenuated the neuronal hyperexcitability in response to mechanical stimuli. In immunohistochemical studies, astrocytes and microglia in rats with spinal hemisection showed significantly increased GFAP and OX-42 expression in both superficial and deep dorsal horns in the lumbar spinal dorsal horn compared to sham controls (*p<0.05) that was prevented in a dose related manner by PPF. In conclusion, our present data support astrocytic and microglial activation that contributes to below-level central neuropathic pain following spinal cord injury. PMID:19332108

  5. AMPKα1 knockout enhances nociceptive behaviors and spinal glutamatergic synaptic activities via production of reactive oxygen species in the spinal dorsal horn.

    PubMed

    Maixner, Dylan W; Yan, Xisheng; Hooks, Shelley B; Weng, Han-Rong

    2016-06-21

    Emerging studies have shown that pharmacological activation of adenosine monophosphate-activated protein kinase (AMPK) produces potent analgesic effects in different animal pain models. Currently, the spinal molecular and synaptic mechanism by which AMPK regulates the pain signaling system remains unclear. To address this issue, we utilized the Cre-LoxP system to conditionally knockout the AMPKα1 gene in the nervous system of mice. We demonstrated that AMPKα1 is imperative for maintaining normal nociception, and mice deficient for AMPKα1 exhibit mechanical allodynia. This is concomitantly associated with increased glutamatergic synaptic activities in neurons located in the superficial spinal dorsal horn, which results from the increased glutamate release from presynaptic terminals and function of ligand-gated glutamate receptors at the postsynaptic neurons. Additionally, AMPKα1 knockout mice have increased activities of extracellular signal-regulated kinases (ERK) and p38 mitogen-activated protein kinases (p38), as well as elevated levels of interleukin-1β (IL-1β), reactive oxygen species (ROS), and heme oxygenase 1 (HO-1) in the spinal dorsal horn. Systemic administration of a non-specific ROS scavenger (phenyl-N-tert-butylnitrone, PBN) or a HO-1 activator (Cobalt protoporphyrin IX, CoPP) attenuated allodynia in AMPKα1 knockout mice. Bath-perfusion of the ROS scavenger or HO-1 activator effectively attenuated the increased ROS levels and glutamatergic synaptic activities in the spinal dorsal horn. Our findings suggest that ROS are the key down-stream signaling molecules mediating the behavioral hypersensitivity in AMPKα1 knockout mice. Thus, targeting AMPKα1 may represent an effective approach for the treatment of pathological pain conditions associated with neuroinflammation at the spinal dorsal horn. PMID:27058143

  6. Respiratory outcomes after mid-cervical transplantation of embryonic medullary cells in rats with cervical spinal cord injury.

    PubMed

    Dougherty, B J; Gonzalez-Rothi, E J; Lee, K Z; Ross, H H; Reier, P J; Fuller, D D

    2016-04-01

    Respiratory motor output after cervical spinal cord injury (cSCI) is profoundly influenced by spinal serotonin. We hypothesized that intraspinal transplantation of embryonic midline brainstem (MB) cells rich in serotonergic raphé neurons would improve respiratory outcomes after cSCI. One week after hemisection of the 2nd cervical segment (C2Hx) a suspension of either embryonic (E14) MB cells, fetal spinal cord cells (FSC), or media only (sham) was delivered to the dorsal C3 spinal cord of adult male rats. Six weeks later, ventilation was evaluated using plethysmography; phrenic nerve activity was evaluated in a subset of rats. Seven of 12 rats receiving MB-derived grafts had clear histological evidence of serotonin-positive neurons in the C3-4 dorsal white matter. The transplantations had no impact on baseline breathing patterns, but during a brief respiratory challenge (7% inspired CO2) rats with successful MB grafts had increased ventilation compared to rats with failed MB grafts, FSC or sham grafts. Recordings from the phrenic nerve ipsilateral to C2Hx also indicated increased output during respiratory challenge in rats with successful MB grafts. We conclude that intraspinal allografting of E14 MB cells can have a positive impact on respiratory motor recovery following high cSCI. PMID:26808660

  7. Patterns of x-radiation-induced Schwann cell development in spinal cords of immature rats

    SciTech Connect

    Gilmore, S.A.; Heard, J.K.; Leiting, J.E.

    1983-03-01

    Schwann cells, Schwann cell myelin, and connective tissue components develop in the spinal cord of the immature rat following exposure to x-rays. For the purposes of this paper, these intraspinal peripheral nervous tissue constituents are referred to as IPNT. A series of investigations are in progress to elucidate factors related to the development of IPNT, and the present study is a light microscopic evaluation of the relationship between the amount of radiation administered (1,000-3,000R) to the lumbosacral spinal cord in 3-day-old rats and the incidence and distribution of IPNT at intervals up to 60 days postirradiation (P-I). The results showed that IPNT was present in only 33% of the rats exposed to 1,000R, whereas its presence was observed in 86% or more of those in the 2,000-, 2,500-, and 3,000R groups. The distribution of IPNT was quite limited in the 1,000R group, where it was restricted to the spinal cord-dorsal root junction and was found in only a few sections within the irradiated area. The distribution was more widespread with increasing amounts of radiation, and IPNT occupied substantial portions of the dorsal funiculi and extended into the dorsal gray matter in the 3,000R group. In all aR mals developing IPNT in the groups receiving 2,000R or more, the IPNT was present in essentially all sections from the irradiated area. Further studies will compare in detail spinal cords exposed to 1,000R in which IPNT is an infrequent, limited occurrence with those exposed to higher doses where IPNT occurs in a more widespread fashion in essentially all animals.

  8. Transgenic mice ectopically expressing HOXA5 in the dorsal spinal cord show structural defects of the cervical spinal cord along with sensory and motor defects of the forelimb.

    PubMed

    Krieger, Karin E; Abbott, Matthew A; Joksimovic, Milan; Lueth, Paul A; Sonea, Ioana M; Jeannotte, Lucie; Tuggle, Christopher K

    2004-06-21

    Mutation of murine Hoxa5 has shown that HOXA5 controls lung, gastrointestinal tract and vertebrae development. Hoxa5 is also expressed in the spinal cord, yet no central nervous system phenotype has been described in Hoxa5 knockouts. To identify the role of Hoxa5 in spinal cord development, we developed transgenic mice that express HOXA5 in the dorsal spinal cord in the brachial region. Using HOXA5-specific antibodies, we show this expression pattern is ectopic as the endogenous protein is expressed only in the ventral spinal cord at this anterio-posterior level. This transgenic line (Hoxa5SV2) also displays forelimb-specific motor and sensory defects. Hoxa5SV2 transgenic mice cannot support their body weight in a forelimb hang, and forelimb strength is decreased. However, Rotarod performance was not impaired in Hoxa5SV2 mice. Hoxa5SV2 mice also show a delayed forelimb response to noxious heat, although hindlimb response time was normal. Administration of an analgesic significantly reduced the hang test defect and decreased the transgene effect on forelimb strength, indicating that pain pathways may be affected. The morphology of transgenic cervical (but not lumbar) spinal cord is highly aberrant. Nissl staining indicates superficial laminae of the dorsal horn are severely disrupted. The distribution of cells and axons immunoreactive for substance P, neurokinin-B, and their primary receptors were aberrant only in transgenic cervical spinal cord. Further, we see increased levels of apoptosis in transgenic spinal cord at embryonic day 13.5. Our evidence suggests apoptosis due to HOXA5 misexpression is a major cause of loss of superficial lamina cells in Hoxa5SV2 mice. PMID:15158076

  9. Nesfatin-1 immunoreactivity in rat brain and spinal cord autonomic nuclei

    PubMed Central

    Goebel, Miriam; Stengel, Andreas; Lambrecht, Nils W.G.; Wang, Lixin; Taché, Yvette

    2009-01-01

    Nesfatin-1 is one of the peptide products of posttranslational processing of the nucleobindin-2 (NUCB2) gene, suggested to have physiological relevance to suppress food intake and body weight gain in rats. Nesfatin-1-immunoreactive cells have been found in distinct nuclei in the rat brain related to circuitries regulating food intake. Here, we report novel yet undescribed localization of NUCB2/nesfatin-1 at the mRNA and protein level in the rat central nervous system. Immunohistochemical staining revealed the localization of NUCB2/nesfatin-1 in the piriform and insular cortex, endopiriform nucleus, nucleus accumbens, lateral septum, bed nucleus of stria terminalis, central amygdaloid nucleus, medial preoptic area, dorsal raphe nucleus, ambiguus nucleus, ventrolateral medulla and gigantocellular reticular nucleus, as well as Purkinje-cells of the cerebellum. In the spinal cord, nesfatin-1 immunoreactivity (IR) was found in both sympathetic and parasympathetic preganglionic neuronal groups and in the dorsal area X from lower thoracic to sacral segments. The immunohistochemical results were confirmed by RT-PCR in the central amygdaloid nucleus, nucleus accumbens, cerebellum and lumbar spinal cord microdissected by punch technique. The features and distributions of nesfatin-1 IR and mRNA expression in the brain and spinal cord suggest that NUCB2/nesfatin-1 could play a wider role in autonomic regulation of visceral-endocrine functions besides food intake. PMID:19348732

  10. Identification of spinal 5-HT sub 3 receptors and their role in the modulation of nociceptive responses in the rat

    SciTech Connect

    Glaum, S.R.

    1988-01-01

    The project consisted of two related studies: (1) the characterization of serotonin binding sites in crude and purified synaptic membranes prepared from the rat spinal cord, and (2) the association of serotonin binding sites with functional 5-HT receptor responses in the modulation of nociceptive information at the level of the spinal cord. The first series of experiments involved the preparation of membranes from the dorsal and ventral halves of the rat spinal cord and the demonstration of specific ({sup 3}H)serotonin binding to these membranes. High affinity binding sites which conformed to the 5-HT{sub 3} subtype were identified in dorsal, but not ventral spinal cord synaptic membranes. These experiments also confirmed the presence of high affinity ({sup 3}H)5-HT binding sites in dorsal spinal cord synaptic membranes of the 5-HT{sub 1} subtype. The second group of studies demonstrated the ability of selective 5-HT{sub 3} antagonists to inhibit the antinociceptive response to intrathecally administered 5-HT, as measured by a change in tail flick and hot plate latencies. Intrathecal pretreatment with the selective 5-HT{sub 3} antagonists ICS 205-930 or MDL 72222 abolished the antinociceptive effects of 5-HT. Furthermore, the selective 5-HT{sub 3} agonist 2-methyl-5-HT mimicked the antinociceptive effects of 5-HT.

  11. Teratogenic effects of pyridoxine on the spinal cord and dorsal root ganglia of embryonic chickens.

    PubMed

    Sharp, A A; Fedorovich, Y

    2015-03-19

    Our understanding of the role of somatosensory feedback in regulating motility during chicken embryogenesis and fetal development in general has been hampered by the lack of an approach to selectively alter specific sensory modalities. In adult mammals, pyridoxine overdose has been shown to cause a peripheral sensory neuropathy characterized by a loss of both muscle and cutaneous afferents, but predominated by a loss of proprioception. We have begun to explore the sensitivity of the nervous system in chicken embryos to the application of pyridoxine on embryonic days 7 and 8, after sensory neurons in the lumbosacral region become post-mitotic. Upon examination of the spinal cord, dorsal root ganglion and peripheral nerves, we find that pyridoxine causes a loss of neurotrophic tyrosine kinase receptor type 3-positive neurons, a decrease in the diameter of the muscle innervating nerve tibialis, and a reduction in the number of large diameter axons in this nerve. However, we found no change in the number of Substance P or calcitonin gene-related peptide-positive neurons, the number of motor neurons or the diameter or axonal composition of the femoral cutaneous nerve. Therefore, pyridoxine causes a peripheral sensory neuropathy in embryonic chickens largely consistent with its effects in adult mammals. However, the lesion may be more restricted to proprioception in the chicken embryo. Therefore, pyridoxine lesion induced during embryogenesis in the chicken embryo can be used to assess how the loss of sensation, largely proprioception, alters spontaneous embryonic motility and subsequent motor development. PMID:25592428

  12. Subdural infusion of dexamethasone inhibits leukomyelitis after acute spinal cord injury in a rat model.

    PubMed

    Kwiecien, Jm; Jarosz, B; Urdzikova, L M; Rola, R; Dabrowski, W

    2015-01-01

    Trauma in spinal cord injury often results in massive damage to the white matter and in damage to myelin that results in a severe phagocyte-rich infiltration apparently directed at removing immunologically toxic myelin debris. In the epidural balloon crush injury to the rat cranial thoracic spinal cord, the dorsal column was crushed, which at one week post-op resulted in its obliteration by a severe infiltration by a virtually pure population of macrophages that internalized all damaged myelin. A week-long subdural infusion of dexamethasone, a stable synthetic corticosteroid, resulted in remarkable inhibition of the macrophage infiltration of the crush cavity and in the lack of removal of myelin debris by phagocytosis. In this study we demonstrated that spinal cord injury results in a severe inflammatory response directed at massively damaged myelin, and we inhibited this response with a subdural infusion of a powerful anti-inflammatory drug, dexamethasone. PMID:25909874

  13. The post-natal development of cutaneous afferent fibre input and receptive field organization in the rat dorsal horn.

    PubMed Central

    Fitzgerald, M

    1985-01-01

    The responses evoked in lumbar dorsal horn cells by both natural and electrical hind-limb skin stimulation were recorded in the spinal cord of rat pups aged 0-15 days under urethane anaesthesia. The input volley was recorded on the L4 dorsal root and consisted of two separate waves from birth. Latency and threshold measurements were consistent with these two waves being immature A (myelinated fibre) waves and C (non-myelinated fibre) waves. On the first 3 days of life background activity of cells in the dorsal horn was low and evoked discharges were sluggish. On electrical stimulation of the skin, neonatal dorsal horn cells frequently responded with only 1 or 2 impulses per input volley with long central delays of up to 20 ms. Synaptic linkage appeared weak and many cells failed to follow stimulation rates of 5 Hz. Natural skin stimulation showed that the majority of cells at days 0-3 responded to pinching the skin only. The development of responses evoked by C fibres in the dorsal horn was delayed compared to that of responses evoked by A fibres. Short and long latency responses corresponding to the early A and late C afferent input volleys could be recorded in the superficial laminae (I, II and III) of the dorsal horn from day 0, but in the deeper laminae only early short latency A responses were evoked until the age of day 7-8. After this time, a long latency C response also appeared and increased in strength with age. Convergence of low and high threshold inputs onto dorsal horn cells was rare at birth but increased gradually over the following two weeks. Receptive field areas, mapped by natural mechanical stimulation of skin, were large at birth and decreased in size with age. At birth the mean receptive field area was 14.2% of the total hind-limb area whereas at day 15 it was 3.6%. This fall in size was particularly marked in cells of the deep dorsal horn. Pinching or brushing the receptive field of many neonatal dorsal horn cells resulted in long

  14. Meso-diencephalic regions projecting to spinal cord and dorsal column nuclear complex in the hedgehog-tenrec, Echinops telfairi.

    PubMed

    Künzle, H

    1992-01-01

    The distribution of neurons projecting to the spinal cord and dorsal column nuclear complex was investigated in the mesodiencephalic regions of the lesser hedgehog-tenrec, Echinops telfairi (Insectivora) by using the retrograde flow technique. While only few neurons projected to the dorsal column nuclear complex, numerous cells were found to give rise to spinal projections. Rubro-spinal neurons of various sizes were distributed over the entire rostrocaudal extent of the contra-lateral nucleus; a few neurons were also located ipsilaterally, Unlike that of the opossum, the projection appeared to be somatotopically organised. Interstitio-spinal neurons were differentiated into several subpopulations according to their location and laterality of projection. In the ipsilateral periventricular grey, in addition, there was a distinct population of cells possibly corresponding to the nucleus of Darkschewitsch. The mesencephalic central grey contained relatively few labeled neurons, the great majority of them being mesencephalic trigeminal, ectopic cuneiform or midline cells. Labeled cuneiform and midline cells, on the other hand, were quite numerous, extending both from a level just caudal to the trochlear nucleus to levels far beyond the rostral tip of the somatic oculomotor nucleus. The discrepancy between the poorly differentiated oculomotor nuclei and the apparently well-developed Edinger-Westphal complex is discussed. Hypothalamo-spinal neurons were essentially restricted to dorsal regions: the hypothalamic paraventricular nucleus (PAV), the dorso-medial (DmHy) and dorso-intermediate cell groups as well as the lateral hypothalamic zone. The latter two cell groups were bilaterally labeled, while the labeled neurons in DmHy and PAV were located predominantly ipsilaterally. Labeled neurons in the amygdala, colliculus superior and mesencephalic trigeminal nucleus were only found following cervical injections; all other mentioned areas and the posterior commissure complex

  15. Principles of electrical stimulation and dorsal column mapping as it relates to spinal cord stimulation: an overview.

    PubMed

    Ramasubbu, Chitra; Flagg, Artemus; Williams, Kayode

    2013-02-01

    The last 30 years have witnessed the growth of spinal cord stimulation as a treatment modality for an increasing number of chronic pain conditions. In spite of this growth, one of the greatest criticisms is the lack of concrete evidence for the mechanism of action. With the ever increasing enlightenment with regards to the neurophysiology of pain, and the development of more dynamic neuroimaging techniques, the opportunity to better define the mechanism of action of the spinal cord stimulator will continue to expand. In the interim, clinicians will benefit from the consolidation of the available knowledge that will enhance the effective use of the device. This review serves to provide an overview of the key principles of electrical stimulation and dorsal column mapping as it relates to spinal cord stimulation. We aim at enhancing the understanding regarding the basis for successful placement of leads and manipulation of electrical parameters. PMID:23299905

  16. Abnormal DNA methylation in the lumbar spinal cord following chronic constriction injury in rats.

    PubMed

    Wang, Ying; Lin, Zhi-Ping; Zheng, Hui-Zhe; Zhang, Shuang; Zhang, Zong-Luan; Chen, Yan; You, Yi-Sheng; Yang, Ming-Hua

    2016-01-01

    Pathogenesis of neuropathic pain is complex and not clearly understood. Glutamate decarboxylase 67 (GAD 67) is a key synthetic enzyme for the main inhibitory transmitter gamma-aminobutyric acid (GABA), and diminishes in the spinal dorsal horn in rats following chronic constriction injury (CCI). GAD 67 is coded by gene GAD 1. DNA methylation can regulate the expression of GAD 67 by regulating the methylation of GAD 1 promoter in the psychotic brain. DNA methylation is primarily mediated by DNA methyltransferases (DNMTs) and methyl-DNA binding domain proteins (MBDs). In this study, in order to discover whether DNA methylation regulates GAD 67 expression in the spinal cord in CCI rats and is involved in neuropathic pain, we examined mRNA levels of DNMTs, MBDs and GAD 67 with real-time reverse transcriptase-polymerase chain reaction (qRT-PCR), and methylation of GAD 1 promoter with Pyromark CpG Assays in the lumbar spinal cord in CCI rats on day 14 after surgery. Our results showed that DNMT3a, DNMT3b and methyl-CpG binding protein 2 (MeCP2) expression increased, MBD2 expression decreased, and DNMT1, MBD1 and MBD3 expression hardly changed in the lumbar spinal cord in CCI rats on day 14 after surgery. GAD 67 expression decreased, and methylation of GAD 1 promoter increased in the lumbar spinal cord in CCI rats on day 14 after surgery. These results indicate that decreased GAD 67 may be associated with increased GAD 1 promoter methylation, which may be mediated by DNMT3a, DNMT3b, MeCP2 and MBD2 in CCI rats. These indicate that abnormal DNA methylation may be highly involved in CCI-induced neuropathic pain. PMID:26515497

  17. Blockade of spinal glutamate recycling produces paradoxical antinociception in rats with orofacial inflammatory pain.

    PubMed

    Yang, Kui Y; Mun, Jun H; Park, Ki D; Kim, Min J; Ju, Jin S; Kim, Seong T; Bae, Yong C; Ahn, Dong K

    2015-03-01

    In our current study, we investigated the role of spinal glutamate recycling in the development of orofacial inflammatory pain. DL-threo-β-benzyloxyaspartate (TBOA) or methionine sulfoximine (MSO) was administered intracisternally to block spinal glutamate transporter and glutamine synthetase activity in astroglia. Intracisternal administration of high dose TBOA (10 μg) produced thermal hyperalgesia in naïve rats but significantly attenuated the thermal hyperalgesia in rats that had been pretreated with interleukin (IL)-1β or Complete Freund's Adjuvant (CFA). In contrast, intracisternal injection of MSO produced anti-hyperalgesic effects against thermal stimuli in CFA-treated rats only. To confirm the paradoxical antinociceptive effects of TBOA and MSO, we examined changes in c-Fos expression in the medullary dorsal horn produced by thermal stimulation in naïve, IL-1β-, or CFA-treated rats, after intracisternal injections of TBOA and MSO. Intracisternal administration of TBOA significantly increased c-Fos immunoreactivity in naïve rats. In contrast, intracisternal administration of TBOA significantly decreased the up-regulation of c-Fos immunoreactivity in the medullary dorsal horn of IL-1β- and CFA-treated rats. However, intracisternal injection of MSO blocked the up-regulation of c-Fos immunoreactivity in CFA-treated rats only. We also investigated the effects of botulinum toxin type A (BoNT-A) on TBOA-induced paradoxical antinociception in CFA-treated rats, as BoNT-A inhibits the release of neurotransmitters, including glutamate. BoNT-A treatment reversed behavioral responses produced by intracisternal administration of TBOA in CFA-treated rats. These results suggest that the paradoxical responses produced by blocking glutamate transporters under inflammatory pain conditions are mediated by the modulation of glutamate release from presynaptic terminals. Moreover, blockade of glutamate reuptake could represent a new therapeutic target for the treatment of

  18. Hyperbaric oxygen preconditioning attenuates early apoptosis after spinal cord ischemia in rats.

    PubMed

    Wang, Liping; Li, Wenxian; Kang, Zhimin; Liu, Yun; Deng, Xiaoming; Tao, Hengyi; Xu, Weigang; Li, Runping; Sun, Xuejun; Zhang, John H

    2009-01-01

    This study tested the hypothesis that spinal cord ischemic tolerance induced by hyperbaric oxygen preconditioning (HBO-PC) is mediated by inhibition of early apoptosis. Male Sprague-Dawley rats were preconditioned with consecutive 4 cycles of 1-h HBO exposures (2.5 atmospheres absolute [ATA], 100% O(2)) at a 12-h interval. At 24 h after the last HBO pretreatment, rats underwent 9 min of spinal cord ischemia induced by occlusion of the descending thoracic aorta in combination with systemic hypotension (40 mmHg). Spinal cord ischemia produced marked neuronal death and neurological dysfunction in animals. HBO-PC enhanced activities of Mn-superoxide dismutase (Mn-SOD) and catalase, as well as the expression of Bcl-2 in the mitochondria in the normal spinal cord at 24 h after the last pretreatment (before spinal cord ischemia), and retained higher levels throughout the early reperfusion in the ischemic spinal cord. In parallel, superoxide and hydrogen peroxide levels in mitochondria were decreased, cytochrome c release into the cytosol was reduced at 1 h after reperfusion, and activation of caspase-3 and -9 was subsequently attenuated. HBO-PC improved neurobehavioral scores and reduced neuronal apoptosis in the anterior, intermediate, and dorsal gray matter of lumbar segment at 24 h after spinal cord ischemia. HBO-PC increased nitric oxide (NO) production. L-nitroarginine-methyl-ester (L-NAME; 10 mg/kg), a nonselective NO synthase (NOS) inhibitor, applied before each HBO-PC protocol abolished these beneficial effects of HBO-PC. We conclude that HBO-PC reduced spinal cord ischemia-reperfusion injury by increasing Mn-SOD, catalase, and Bcl-2, and by suppressing mitochondrial apoptosis pathway. NO may be involved in this neuroprotection. PMID:19196076

  19. Different types of spinal afferent nerve endings in stomach and esophagus identified by anterograde tracing from dorsal root ganglia.

    PubMed

    Spencer, Nick J; Kyloh, Melinda; Beckett, Elizabeth A; Brookes, Simon; Hibberd, Tim

    2016-10-15

    In visceral organs of mammals, most noxious (painful) stimuli as well as innocuous stimuli are detected by spinal afferent neurons, whose cell bodies lie in dorsal root ganglia (DRGs). One of the major unresolved questions is the location, morphology, and neurochemistry of the nerve endings of spinal afferents that actually detect these stimuli in the viscera. In the upper gastrointestinal (GI) tract, there have been many anterograde tracing studies of vagal afferent endings, but none on spinal afferent endings. Recently, we developed a technique that now provides selective labeling of only spinal afferents. We used this approach to identify spinal afferent nerve endings in the upper GI tract of mice. Animals were anesthetized, and injections of dextran-amine were made into thoracic DRGs (T8-T12). Seven days post surgery, mice were euthanized, and the stomach and esophagus were removed, fixed, and stained for calcitonin gene-related peptide (CGRP). Spinal afferent axons were identified that ramified extensively through many rows of myenteric ganglia and formed nerve endings in discrete anatomical layers. Most commonly, intraganglionic varicose endings (IGVEs) were identified in myenteric ganglia of the stomach and varicose simple-type endings in the circular muscle and mucosa. Less commonly, nerve endings were identified in internodal strands, blood vessels, submucosal ganglia, and longitudinal muscle. In the esophagus, only IGVEs were identified in myenteric ganglia. No intraganglionic lamellar endings (IGLEs) were identified in the stomach or esophagus. We present the first identification of spinal afferent endings in the upper GI tract. Eight distinct types of spinal afferent endings were identified in the stomach, and most of them were CGRP immunoreactive. J. Comp. Neurol. 524:3064-3083, 2016. © 2016 Wiley Periodicals, Inc. PMID:27019197

  20. Validity of acute and chronic tactile sensory testing after spinal cord injury in rats

    PubMed Central

    Detloff, Megan Ryan; Clark, Leslie M.; Hutchinson, Karen J.; Kloos, Anne D.; Fisher, Lesley C.; Basso, D. Michele

    2016-01-01

    Spinal cord injury (SCI) impairs sensory systems causing allodynia. Measuring the development of allodynia in rodent models of SCI is challenging due to spinal shock and marked motor impairments. Assessment of SCI-induced allodynia is not standardized across labs, making interpretation of results difficult. Therefore, we validated sensory threshold assessment after SCI and developed a novel assessment of allodynia prior to motor recovery in a rat SCI model. One hundred fifty-six Sprague–Dawley rats received T8 laminectomy or mild to moderate SCI using the OSU SCI device (0.3 mm to 1.3mm cord displacement). To determine tactile thresholds, von Frey hairs (VFH) were applied in Up–Down or ascending order to the dorsal or plantar hindpaw. The most efficient and valid procedures that maintain high sensitivity and specificity were identified. Ten Up–Down VFH applications yielded stable thresholds; reducing the risk of threshold decay and unnecessary exposure to painful stimuli. Importantly, distraction of SCI-rats with food revealed differential decay of thresholds than when distraction is not provided. The new test uses dorsal VFH stimulation and is independent of trunk or hindlimb control. Acute dorsal VFH thresholds collected before recovery of hindlimb weight support accurately predicted plantar VFH thresholds measured at late timepoints (χ2=8.479; p<0.05). Thus, standardized testing early after SCI using the dorsal VFH test or later using 10 stimuli in the Up–Down test produces valid measures of tactile sensation across many SCI severities. Early detection of allodynia in experimental SCI will allow identification of mechanisms responsible for pain development and determine targets for therapeutic interventions. PMID:20643128

  1. Validity of acute and chronic tactile sensory testing after spinal cord injury in rats.

    PubMed

    Detloff, Megan Ryan; Clark, Leslie M; Hutchinson, Karen J; Kloos, Anne D; Fisher, Lesley C; Basso, D Michele

    2010-10-01

    Spinal cord injury (SCI) impairs sensory systems causing allodynia. Measuring the development of allodynia in rodent models of SCI is challenging due to spinal shock and marked motor impairments. Assessment of SCI-induced allodynia is not standardized across labs, making interpretation of results difficult. Therefore, we validated sensory threshold assessment after SCI and developed a novel assessment of allodynia prior to motor recovery in a rat SCI model. One hundred fifty-six Sprague-Dawley rats received T8 laminectomy or mild to moderate SCI using the OSU SCI device (0.3 mm to 1.3 mm cord displacement). To determine tactile thresholds, von Frey hairs (VFH) were applied in Up-Down or ascending order to the dorsal or plantar hindpaw. The most efficient and valid procedures that maintain high sensitivity and specificity were identified. Ten Up-Down VFH applications yielded stable thresholds; reducing the risk of threshold decay and unnecessary exposure to painful stimuli. Importantly, distraction of SCI-rats with food revealed differential decay of thresholds than when distraction is not provided. The new test uses dorsal VFH stimulation and is independent of trunk or hindlimb control. Acute dorsal VFH thresholds collected before recovery of hindlimb weight support accurately predicted plantar VFH thresholds measured at late timepoints (chi(2)=8.479; p<0.05). Thus, standardized testing early after SCI using the dorsal VFH test or later using 10 stimuli in the Up-Down test produces valid measures of tactile sensation across many SCI severities. Early detection of allodynia in experimental SCI will allow identification of mechanisms responsible for pain development and determine targets for therapeutic interventions. PMID:20643128

  2. Lidocaine Inhibits HCN Currents in Rat Spinal Substantia Gelatinosa Neurons

    PubMed Central

    Hu, Tao; Liu, Nana; Lv, Minhua; Ma, Longxian; Peng, Huizhen; Peng, Sicong

    2016-01-01

    BACKGROUND: Lidocaine, which blocks voltage-gated sodium channels, is widely used in surgical anesthesia and pain management. Recently, it has been proposed that the hyperpolarization-activated cyclic nucleotide (HCN) channel is one of the other novel targets of lidocaine. Substantia gelatinosa in the spinal dorsal horn, which plays key roles in modulating nociceptive information from primary afferents, comprises heterogeneous interneurons that can be electrophysiologically categorized by firing pattern. Our previous study demonstrated that a substantial proportion of substantia gelatinosa neurons reveal the presence of HCN current (Ih); however, the roles of lidocaine and HCN channel expression in different types of substantia gelatinosa neurons remain unclear. METHODS: By using the whole-cell patch-clamp technique, we investigated the effect of lidocaine on Ih in rat substantia gelatinosa neurons of acute dissociated spinal cord slices. RESULTS: We found that lidocaine rapidly decreased the peak Ih amplitude with an IC50 of 80 μM. The inhibition rate on Ih was not significantly different with a second application of lidocaine in the same neuron. Tetrodotoxin, a sodium channel blocker, did not affect lidocaine’s effect on Ih. In addition, lidocaine shifted the half-activation potential of Ih from −109.7 to −114.9 mV and slowed activation. Moreover, the reversal potential of Ih was shifted by −7.5 mV by lidocaine. In the current clamp, lidocaine decreased the resting membrane potential, increased membrane resistance, delayed rebound depolarization latency, and reduced the rebound spike frequency. We further found that approximately 58% of substantia gelatinosa neurons examined expressed Ih, in which most of them were tonically firing. CONCLUSIONS: Our studies demonstrate that lidocaine strongly inhibits Ih in a reversible and concentration-dependent manner in substantia gelatinosa neurons, independent of tetrodotoxin-sensitive sodium channels. Thus, our

  3. Macrophage-Colony Stimulating Factor Derived from Injured Primary Afferent Induces Proliferation of Spinal Microglia and Neuropathic Pain in Rats.

    PubMed

    Okubo, Masamichi; Yamanaka, Hiroki; Kobayashi, Kimiko; Dai, Yi; Kanda, Hirosato; Yagi, Hideshi; Noguchi, Koichi

    2016-01-01

    Peripheral nerve injury induces proliferation of microglia in the spinal cord, which can contribute to neuropathic pain conditions. However, candidate molecules for proliferation of spinal microglia after injury in rats remain unclear. We focused on the colony-stimulating factors (CSFs) and interleukin-34 (IL-34) that are involved in the proliferation of the mononuclear phagocyte lineage. We examined the expression of mRNAs for macrophage-CSF (M-CSF), granulocyte macrophage-CSF (GM-CSF), granulocyte-CSF (G-CSF) and IL-34 in the dorsal root ganglion (DRG) and spinal cord after spared nerve injury (SNI) in rats. RT-PCR and in situ hybridization revealed that M-CSF and IL-34, but not GM- or G-CSF, mRNAs were constitutively expressed in the DRG, and M-CSF robustly increased in injured-DRG neurons. M-CSF receptor mRNA was expressed in naive rats and increased in spinal microglia following SNI. Intrathecal injection of M-CSF receptor inhibitor partially but significantly reversed the proliferation of spinal microglia and in early phase of neuropathic pain induced by SNI. Furthermore, intrathecal injection of recombinant M-CSF induced microglial proliferation and mechanical allodynia. Here, we demonstrate that M-CSF is a candidate molecule derived from primary afferents that induces proliferation of microglia in the spinal cord and leads to induction of neuropathic pain after peripheral nerve injury in rats. PMID:27071004

  4. Macrophage-Colony Stimulating Factor Derived from Injured Primary Afferent Induces Proliferation of Spinal Microglia and Neuropathic Pain in Rats

    PubMed Central

    Okubo, Masamichi; Yamanaka, Hiroki; Kobayashi, Kimiko; Dai, Yi; Kanda, Hirosato; Yagi, Hideshi; Noguchi, Koichi

    2016-01-01

    Peripheral nerve injury induces proliferation of microglia in the spinal cord, which can contribute to neuropathic pain conditions. However, candidate molecules for proliferation of spinal microglia after injury in rats remain unclear. We focused on the colony-stimulating factors (CSFs) and interleukin-34 (IL-34) that are involved in the proliferation of the mononuclear phagocyte lineage. We examined the expression of mRNAs for macrophage-CSF (M-CSF), granulocyte macrophage-CSF (GM-CSF), granulocyte-CSF (G-CSF) and IL-34 in the dorsal root ganglion (DRG) and spinal cord after spared nerve injury (SNI) in rats. RT-PCR and in situ hybridization revealed that M-CSF and IL-34, but not GM- or G-CSF, mRNAs were constitutively expressed in the DRG, and M-CSF robustly increased in injured-DRG neurons. M-CSF receptor mRNA was expressed in naive rats and increased in spinal microglia following SNI. Intrathecal injection of M-CSF receptor inhibitor partially but significantly reversed the proliferation of spinal microglia and in early phase of neuropathic pain induced by SNI. Furthermore, intrathecal injection of recombinant M-CSF induced microglial proliferation and mechanical allodynia. Here, we demonstrate that M-CSF is a candidate molecule derived from primary afferents that induces proliferation of microglia in the spinal cord and leads to induction of neuropathic pain after peripheral nerve injury in rats. PMID:27071004

  5. The antiallodynic action of pregabalin may depend on the suppression of spinal neuronal hyperexcitability in rats with spared nerve injury

    PubMed Central

    Ding, Lei; Cai, Jie; Guo, Xiang-Yang; Meng, Xiu-Li; Xing, Guo-Gang

    2014-01-01

    BACKGROUND: Pregabalin (PGB) is a novel antiepileptic drug and is also used as a first-line medication for the treatment of neuropathic pain. However, the mechanisms of its analgesic effects remain largely unknown. OBJECTIVES: To elucidate the mechanisms underlying the antiallodynic action of PGB in rats with neuropathic pain. METHODS: In a rat model of neuropathic pain induced by spared nerve injury, mechanical allodynia, as a behavioural sign of neuropathic pain, was assessed by measuring 50% paw withdrawal threshold with von Frey filaments. Activities of dorsal horn wide dynamic range (WDR) neurons were examined by extracellular electrophysiological recording in vivo. RESULTS: Spinal administration of PGB exerted a significant antiallodynic effect and a prominent inhibitory effect on the hypersensitivity of dorsal horn WDR neurons in rats with spared nerve injury. CONCLUSION: The antiallodynic action of PGB is likely dependent on the suppression of WDR neuron hyperexcitability in rats with neuropathic pain. PMID:24851240

  6. Neural coding of nociceptive stimuli-from rat spinal neurones to human perception.

    PubMed

    Sikandar, Shafaq; Ronga, Irene; Iannetti, Gian Domenico; Dickenson, Anthony H

    2013-08-01

    Translational studies are key to furthering our understanding of nociceptive signalling and bridging the gaps between molecules and pathways to the patients. This requires use of appropriate preclinical models that accurately depict outcome measures used in humans. Whereas behavioural animal studies classically involve reports related to nociceptive thresholds of, for example, withdrawal, electrophysiological recordings of spinal neurones that receive convergent input from primary afferents permits investigation of suprathreshold events and exploration of the full-range coding of different stimuli. We explored the central processing of nociceptive inputs in a novel parallel investigation between rats and humans. Using radiant laser pulses, we first compared the electrophysiological responses of deep wide dynamic range and superficial nociceptive-specific neurones in the rat dorsal horn with human psychophysics and cortical responses. Secondly, we explored the effects of spatial summation using laser pulses of identical energy and different size. We observed 3 main findings. Firstly, both rodent and human data confirmed that neodymium-yttrium aluminium perovskite laser stimulation is a nociceptive-selective stimulus that never activates Aβ afferents. Secondly, graded laser stimulation elicited similarly graded electrophysiological and behavioural responses in both species. Thirdly, there was a significant degree of spatial summation of laser nociceptive input. The remarkable similarity in rodent and human coding indicates that responses of rat dorsal horn neurones can translate to human nociceptive processing. These findings suggest that recordings of spinal neuronal activity elicited by laser stimuli could be a valuable predictive measure of human pain perception. PMID:23719576

  7. 5-HT potentiation of the GABAA response in the rat sacral dorsal commissural neurones

    PubMed Central

    Xu, Tian-Le; Pang, Zhi-Ping; Li, Ji-Shuo; Akaike, Norio

    1998-01-01

    The modulatory effect of 5-hydroxytryptamine (5-HT) on the γ-aminobutyric acidA (GABAA) response was investigated in the neurones freshly dissociated from the rat sacral dorsal commissural nucleus (SDCN) using the nystatin perforated patch recording configuration under the voltage-clamp conditions.5-HT potentiated GABA-induced Cl− current (IGABA) without affecting the reversal potential of IGABA and the apparent affinity of GABA to its receptor.α-Methyl-5-HT mimicked the potentiation effect of 5-HT on IGABA while ketanserine blocked it. 1-Oleoyl-2-acetyl-glycerol (OAG) potentiated IGABA, and the effect of 5-HT on IGABA was occluded by OAG pretreatment. In the presence of chelerythrine, 5-HT failed to potentiate IGABA, suggesting that protein kinase C (PKC) is involved in the pathway through which the activation of the 5-HT2 receptor potentiates the IGABA.The facilitatory effect of 5-HT on IGABA remained in the presence of BAPTA-AM. LiCl also had no effect on 5-HT-induced potentiation of IGABA.H-89, genistein, okadaic acid and pervanadate all had no effects on 5-HT potentiation of IGABA. Pertussis toxin treatment for 6–8 h did not block the facilitatory effect of 5-HT on IGABA.The present results show that GABAA receptor in the rat SDCN could be modulated in situ by 5-HT, one of the major transmitters involved in the supraspinal control of nociception, and that the phosphorylation of GABAA receptor by PKC may be sufficient to support such modulation. The results also strongly support the hypothesis that the cotransmission by 5-HT and GABA has an important role in the spinal cord. PMID:9690871

  8. Marked Increase in Nitric Oxide Synthase mRNA in Rat Dorsal Root Ganglia after Peripheral Axotomy: In situ Hybridization and Functional Studies

    NASA Astrophysics Data System (ADS)

    Verge, Valerie M. K.; Xu, Zhang; Xu, Xiao-Jun; Wiesenfeld-Hallin, Zsuzsanna; Hokfelt, Tomas

    1992-12-01

    Using in situ hybridization, we studied nitric oxide (NO) synthase (EC 1.14.23.-) mRNA in lumbar dorsal root ganglia after peripheral transection of the sciatic nerve in rats. The effect of the NO synthase inhibitor N^ω-nitro-L-arginine methyl ester on the nociceptive flexor reflex was also studied in axotomized rats. Nerve section induced a dramatic increase in number of NO synthase mRNA-positive cells in the ipsilateral dorsal root ganglia. In some of these cells the peptides galanin and/or vasoactive intestinal polypeptide and/or neuropeptide Y were also strongly up-regulated. Intravenous administration of nitro-L-arginine methyl ester blocked spinal hyperexcitability at much lower dosages in axotomized than in normal animals. The results suggest involvement of NO in the function of lumbar sensory neurons, especially after axotomy, perhaps preferentially at peripheral sites.

  9. Deafferentation is insufficient to induce sprouting of A-fibre central terminals in the rat dorsal horn.

    PubMed

    Mannion, R J; Doubell, T P; Gill, H; Woolf, C J

    1998-04-01

    The mechanism by which A-fibres sprout into lamina II of the dorsal horn of the adult rat after peripheral nerve injury, a region which normally receives input from noci- and thermoreceptive C-fibres alone, is not known. Recent findings indicating that selective C-fibre injury and subsequent degenerative changes in this region are sufficient to induce sprouting of uninjured A-fibres have raised the possibility that the structural reorganisation of A-fibre terminals is an example of collateral sprouting, in that deafferentation of C-fibre terminals alone in lamina II may be sufficient to cause A-fibre sprouting. Primary afferents of the sciatic nerve have their cell bodies located predominantly in the L4 and L5 dorsal root ganglia (DRGs), and the A-fibres of each DRG have central termination fields that show an extensive rostrocaudal overlap in lamina III in the L4 and L5 spinal segments. In this study, we have found that C-fibres from either DRG have central terminal fields that overlap much less in lamina II than A-fibres in lamina III. We have exploited this differential terminal organisation to produce deafferentation in lamina II of the L5 spinal segment, by an L5 rhizotomy, and then test whether A-fibres of the intact L4 dorsal root ganglion, which terminate within the L5 segment, sprout into the denervated lamina II in the L5 spinal segment. Neither intact nor peripherally injured A-fibres were seen to sprout into denervated lamina II after L5 rhizotomy. Sprouting was only ever seen into regions of lamina II containing the terminals of peripherally injured C-fibres. Therefore, it seems that the creation of synaptic space within lamina II is not the explanation for A-fibre sprouting after peripheral nerve section or crush, emphasising that injury-induced changes in C-fibres and subsequent chemotrophic effects in the superficial dorsal horn are the likely explanation. PMID:9548693

  10. Blockade of capsaicin-induced reduction of GABA-immunoreactivity by spantide in cat spinal superficial dorsal horn.

    PubMed

    Wei, F; Zhao, Z Q

    1996-03-01

    In our previous study, perineural application of capsaicin not only produced release and depletion of substance P from primary nociceptive afferent terminals, but also reduced GABA immunoreactivity in the superficial dorsal horn. The aim of the present study was to determine whether the release of GABA is triggered by substance P released from primary nociceptive afferent terminals by capsaican. GABA and substance P immunoreactivity in the lumbar dorsal horn was examined in two groups: in the first group the tibial nerve was treated with 3% capsaicin, and in the second group the dorsal surface of the lumbar cord was infused with spantide (50 nM), a substance P receptor antagonist, before application of capsaicin to the tibial nerve. Following perineural treatment of capsaicin for 30 min, both the GABA-immunostaining density and the number of GABA immunoreactive neurons were reduced significantly in the ipsilateral laminae I-II at L5 through L7. GABA immunoreactivity was reduced by 54.12%, 44.46% and 31.0% in the medial, central and lateral parts of the ipsilateral laminae I-II at L7, respectively. With pre-application of spantide to the spinal cord, GABA immunoreactivity was reduced only to 14.4%, 16.4% and 10.16%, respectively, in the medial, central and lateral parts of laminae I-II at L7 and no reduction of GABA immunoreactive neurons was observed. Additionally, capsaicin-induced reduction of substance P immunoreactivity was partially blocked by spantide. These results suggest that capsaicin produces substance P release from primary nociceptive afferent terminals, and that substance P, in turn, activates the second-order GABAergic interneurons in the dorsal horn. The functional significance of capsaicin-induced activation of GABAergic neurons in modulation of spinal nociception is discussed. PMID:8834409

  11. The antinociceptive action of etorphine in the dorsal horn is due to a direct spinal action and not to activation of descending inhibition.

    PubMed Central

    Clark, S. L.; Ryall, R. W.

    1983-01-01

    1--Etorphine, microinjected into the brainstem or administered intravenously, inhibited the firing of dorsal horn neurones to noxious heat in spinal or non-spinal anaesthetized cats and in decerebrate, non-anaesthetized cats with intact spinal cords. 2--Small doses of etorphine sometimes caused facilitation, especially when the cord was intact, but this was invariably followed by inhibition at higher doses. 3--The ED50 for inhibition (mean 3.9 micrograms/kg) after microinjection into nucleus raphe magnus, nucleus reticularis magnocellularis or the lateral tegmental field was similar at all sites in anaesthetized, non-spinal cats. 4--The ED50 for microinjection was not increased by spinal transection in anaesthetized cats (mean ED50, 2.6 micrograms/kg) and was similar to the ED50 in decerebrate, non-anaesthetized cats. 5--Intravenous administration was 2 to 3 times more effective than microinjection and the time course of inhibition was faster after intravenous administration than after microinjection. 6--It is concluded that etorphine inhibits dorsal horn neurones after microinjection or intravenous administration by a direct action on the spinal cord and not by activating a descending inhibition. After microinjection it rapidly enters the general circulation and subsequently distributes into the spinal cord. 7--It is also concluded that naloxone readily gains entry to the circulation from the brain because microinjection antagonized the effects of systemic etorphine on dorsal horn neurones in spinal cats. PMID:6338986

  12. Spinal translocator protein alleviates chronic neuropathic pain behavior and modulates spinal astrocyte-neuronal function in rats with L5 spinal nerve ligation model.

    PubMed

    Liu, Xiaoming; Liu, Hongjun; Xu, Shuangshuang; Tang, Zongxiang; Xia, Weiliang; Cheng, Zhuqiang; Li, Weiyan; Jin, Yi

    2016-01-01

    Recent studies reported the translocator protein (TSPO) to play critical roles in several kinds of neurological diseases including the inflammatory and neuropathic pain. However, the precise mechanism remains unclear. This study was undertaken to explore the distribution and possible mechanism of spinal TSPO against chronic neuropathic pain (CNP) in a rat model of L5 spinal nerve ligation (SNL). Our results showed that TSPO was upregulated in a time-related manner in the spinal dorsal horn after SNL. Spinal TSPO was predominately expressed in astrocytes. A single intrathecal injection of TSPO agonist Ro5-4864, but not TSPO antagonist PK11195, alleviated the mechanical allodynia in a dose-dependent manner. A single intraspinal injection of TSPO overexpression lentivirus (LV-TSPO), but not TSPO inhibited lentivirus (LV-shTSPO), also relieved the development of CNP. Intrathecal administration of 2 μg Ro5-4864 on day 3 induced a significant increase of TSPO protein content at the early stage (days 5-7) while inhibited the TSPO activation during the chronic period (days 14-21) compared with the control group. Ro5-4864 suppressed the astrocytes and p-JNK1 activation and decreased the CXCL1 expression in both in vivo and in vitro studies. Ro5-4864 also attenuated the spinal CXCR2 and p-ERK expressions. These results suggested that early upregulation of TSPO could elicit potent analgesic effects against CNP, which might be partly attributed to the inhibition of CXCL1-CXCR2-dependent astrocyte-to-neuron signaling and central sensitization. TSPO signaling pathway may present a novel strategy for the treatment of CNP. PMID:26307860

  13. Deafferentation causes a loss of presynaptic bombesin receptors and supersensitivity of substance P receptors in the dorsal horn of the cat spinal cord.

    PubMed

    Massari, V J; Shults, C W; Park, C H; Tizabi, Y; Moody, T W; Chronwall, B M; Culver, M; Chase, T N

    1985-09-23

    Bombesin (BN)- and substance P (SP)-containing neurons are found in the dorsal root ganglia, and project to the dorsal horn of the spinal cord. The present study was undertaken to determine if chronic deafferentation of the cat spinal cord would affect BN or SP receptors in the spinal cord. Ten and 30 days after a unilateral lumbosacral dorsal rhizotomy, BN and SP receptor binding was evaluated autoradiographically using iodinated ligands to bind to these receptors in vitro. The normal distribution of BN receptors detected by this method was restricted to the head of the dorsal horn. Deafferentation caused a 38% and 22% decline in BN receptor binding in laminae I-IV at 10 or 30 days postoperatively, respectively. These data suggest that 'presynaptic' BN receptors are found on the central nervous system terminals of primary sensory afferents. Normal SP receptor distribution was most dense in lamina X, not in the superficial laminae of the dorsal horn. Deafferentation caused an initial decline in SP receptor binding in laminae I-II, followed by a 14% increase at 30 days in comparison to the unoperated side of the spinal cord. This delayed supersensitivity of SP receptors was confirmed in a separate experiment using a homogenate binding assay. These data are discussed with respect to the potential roles of receptor supersensitivity or subsensitivity in the development of deafferentation-induced changes in reactivity of dorsal horn neurons to nociceptive and non-nociceptive stimuli. PMID:2413960

  14. Sumatriptan inhibits the release of CGRP and substance P from the rat spinal cord.

    PubMed

    Arvieu, L; Mauborgne, A; Bourgoin, S; Oliver, C; Feltz, P; Hamon, M; Cesselin, F

    1996-08-12

    The possible presynaptic action of the anti-migraine drug sumatriptan on primary afferent fibres containing substance P and/or calcitonin gene-related peptide was investigated on superfused rat horizontal spinal cord slices with attached dorsal roots. Electrical stimulation of dorsal roots triggered a significant overflow of both peptides; this could be reduced by sumatriptan in a concentration-dependent manner. As expected from the involvement of 5-HT1B/1.D beta receptors, methiothepin, (-)tertatolol and GR 127,935, but not WAY 100,635, prevented the inhibitors effect of sumatriptan. These data support the idea that the anti-migraine action of sumatriptan may involve, at least in part, a presynaptic inhibitory control of nociceptive (trigeminovascular) substance P- and/or calcitonin gene-related peptide-containing sensory fibres. PMID:8905706

  15. Electrophysiological properties of brain-natriuretic peptide- and gastrin-releasing peptide-responsive dorsal horn neurons in spinal itch transmission.

    PubMed

    Kusube, Fumiya; Tominaga, Mitsutoshi; Kawasaki, Hiroaki; Yamakura, Fumiyuki; Naito, Hisashi; Ogawa, Hideoki; Tomooka, Yasuhiro; Takamori, Kenji

    2016-08-01

    Spinal itch transmission has been reported to be mediated by at least two neuronal populations in spinal dorsal horn, neurons expressing brain-natriuretic peptide (BNP) receptor (Npra) and gastrin-releasing peptide (GRP) receptor (GRPR). Although Npra-expressing neurons were shown to be upstream of GRPR- expressing neurons in spinal itch transmission, the roles of BNP and GRP in the spinal neurotransmission of histamine-dependent and -independent itch remains unclear. Using in vivo electrophysiology and behavior analysis, this study examined the responses of chloroquine (histamine-independent pruritogen)-responsive and histamine-responsive dorsal horn neurons to spinal applications of BNP and GRP. Electrophysiologically, 9.5% of chloroquine-responsive neurons responded to BNP, 33.3% to GRP, and 4.8% to both, indicating that almost half of chloroquine-responsive neurons were unresponsive to both BNP and GRP. In contrast, histamine-responsive neurons did not respond to spinal BNP application, whereas 30% responded to spinal GRP application, indicating that 70% of histamine-responsive neurons were unresponsive to both BNP and GRP. Behavioral analyses showed differences in the time-course and frequency of scratching responses evoked by intrathecal BNP and GRP. These findings provide evidence that most BNP-Npra and GRP-GRPR signaling involve different pathways of spinal itch transmission, and that multiple neurotransmitters, in addition to BNP and GRP, are involved in spinal itch transmission. The electrophysiological results also suggest that spinal BNP contributes little to histaminergic itch directly. PMID:27235577

  16. Spatial and temporal pattern of changes in the number of GAD65-immunoreactive inhibitory terminals in the rat superficial dorsal horn following peripheral nerve injury.

    PubMed

    Lorenzo, Louis-Etienne; Magnussen, Claire; Bailey, Andrea L; St Louis, Manon; De Koninck, Yves; Ribeiro-da-Silva, Alfredo

    2014-01-01

    Inhibitory interneurons are an important component of dorsal horn circuitry where they serve to modulate spinal nociception. There is now considerable evidence indicating that reduced inhibition in the spinal dorsal horn contributes to neuropathic pain. A loss of these inhibitory neurons after nerve injury is one of the mechanisms being proposed to account for reduced inhibition; however, this remains controversial. This is in part because previous studies have focused on global measurements of inhibitory neurons without assessing the number of inhibitory synapses. To address this, we conducted a quantitative analysis of the spatial and temporal changes in the number of inhibitory terminals, as detected by glutamic acid decarboxylase 65 (GAD65) immunoreactivity, in the superficial dorsal horn of the spinal cord following a chronic constriction injury (CCI) to the sciatic nerve in rats. Isolectin B4 (IB4) labelling was used to define the location within the dorsal horn directly affected by the injury to the peripheral nerve. The density of GAD65 inhibitory terminals was reduced in lamina I (LI) and lamina II (LII) of the spinal cord after injury. The loss of GAD65 terminals was greatest in LII with the highest drop occurring around 3-4 weeks and a partial recovery by 56 days. The time course of changes in the number of GAD65 terminals correlated well with both the loss of IB4 labeling and with the altered thresholds to mechanical and thermal stimuli. Our detailed analysis of GAD65+ inhibitory terminals clearly revealed that nerve injury induced a transient loss of GAD65 immunoreactive terminals and suggests a potential involvement for these alterations in the development and amelioration of pain behaviour. PMID:25189404

  17. Are all spinal segments equal: intrinsic membrane properties of superficial dorsal horn neurons in the developing and mature mouse spinal cord

    PubMed Central

    Tadros, M A; Harris, B M; Anderson, W B; Brichta, A M; Graham, B A; Callister, R J

    2012-01-01

    Neurons in the superficial dorsal horn (SDH; laminae I–II) of the spinal cord process nociceptive information from skin, muscle, joints and viscera. Most of what we know about the intrinsic properties of SDH neurons comes from studies in lumbar segments of the cord even though clinical evidence suggests nociceptive signals from viscera and head and neck tissues are processed differently. This ‘lumbar-centric’ view of spinal pain processing mechanisms also applies to developing SDH neurons. Here we ask whether the intrinsic membrane properties of SDH neurons differ across spinal cord segments in both the developing and mature spinal cord. Whole cell recordings were made from SDH neurons in slices of upper cervical (C2–4), thoracic (T8–10) and lumbar (L3–5) segments in neonatal (P0–5) and adult (P24–45) mice. Neuronal input resistance (RIN), resting membrane potential, AP amplitude, half-width and AHP amplitude were similar across spinal cord regions in both neonates and adults (∼100 neurons for each region and age). In contrast, these intrinsic membrane properties differed dramatically between neonates and adults. Five types of AP discharge were observed during depolarizing current injection. In neonates, single spiking dominated (∼40%) and the proportions of each discharge category did not differ across spinal regions. In adults, initial bursting dominated in each spinal region, but was significantly more prevalent in rostral segments (49% of neurons in C2–4 vs. 29% in L3–5). During development the dominant AP discharge pattern changed from single spiking to initial bursting. The rapid A-type potassium current (IAr) dominated in neonates and adults, but its prevalence decreased (∼80%vs. ∼50% of neurons) in all regions during development. IAr steady state inactivation and activation also changed in upper cervical and lumbar regions during development. Together, our data show the intrinsic properties of SDH neurons are generally conserved

  18. Effects of Lateral Funiculus Sparing, Spinal Lesion Level, and Gender on Recovery of Bladder Voiding Reflexes and Hematuria in Rats

    PubMed Central

    Ferrero, Sunny L.; Brady, Tiffany D.; Dugan, Victoria P.; Armstrong, James E.; Hubscher, Charles H.

    2015-01-01

    Abstract Deficits in bladder function are complications following spinal cord injury (SCI), severely affecting quality of life. Normal voiding function requires coordinated contraction of bladder and urethral sphincter muscles dependent upon intact lumbosacral reflex arcs and integration of descending and ascending spinal pathways. We previously reported, in electrophysiological recordings, that segmental reflex circuit neurons in anesthetized male rats were modulated by a bilateral spino-bulbo-spinal pathway in the mid-thoracic lateral funiculus. In the present study, behavioral measures of bladder voiding reflexes and hematuria (hemorrhagic cystitis) were obtained to assess the correlation of plasticity-dependent recovery to the degree of lateral funiculus sparing and mid-thoracic lesion level. Adult rats received mid-thoracic-level lesions at one of the following severities: complete spinal transection; bilateral dorsal column lesion; unilateral hemisection; bilateral dorsal hemisection; a bilateral lesion of the lateral funiculi and dorsal columns; or a severe contusion. Voiding function and hematuria were evaluated by determining whether the bladder was areflexic (requiring manual expression, i.e., “crede maneuver”), reflexive (voiding initiated by perineal stroking), or “automatic” (spontaneous voiding without caretaker assistance). Rats with one or both lateral funiculi spared (i.e., bilateral dorsal column lesion or unilateral hemisection) recovered significantly faster than animals with bilateral lateral funiculus lesions, severe contusion, or complete transection. Bladder reflex recovery time was significantly slower the closer a transection lesion was to T10, suggesting that proximity to the segmental sensory and sympathetic innervation of the upper urinary tract (kidney, ureter) should be avoided in the choice of lesion level for SCI studies of micturition pathways. In addition, hematuria duration was significantly longer in males, compared to

  19. Fluoxetine treatment promotes functional recovery in a rat model of cervical spinal cord injury

    PubMed Central

    Scali, Manuela; Begenisic, Tatjana; Mainardi, Marco; Milanese, Marco; Bonifacino, Tiziana; Bonanno, Giambattista; Sale, Alessandro; Maffei, Lamberto

    2013-01-01

    Spinal cord injury (SCI) is a severe condition leading to enduring motor deficits. When lesions are incomplete, promoting spinal cord plasticity might be a useful strategy to elicit functional recovery. Here we investigated whether long-term fluoxetine administration in the drinking water, a treatment recently demonstrated to optimize brain plasticity in several pathological conditions, promotes motor recovery in rats that received a C4 dorsal funiculus crush. We show that fluoxetine administration markedly improved motor functions compared to controls in several behavioral paradigms. The improved functional effects correlated positively with significant sprouting of intact corticospinal fibers and a modulation of the excitation/inhibition balance. Our results suggest a potential application of fluoxetine treatment as a non invasive therapeutic strategy for SCI-associated neuropathologies. PMID:23860568

  20. Regulation of Nociceptive Plasticity Threshold and DARPP-32 Phosphorylation in Spinal Dorsal Horn Neurons by Convergent Dopamine and Glutamate Inputs.

    PubMed

    Buesa, Itsaso; Aira, Zigor; Azkue, Jon Jatsu

    2016-01-01

    Dopamine can influence NMDA receptor function and regulate glutamate-triggered long-term changes in synaptic strength in several regions of the CNS. In spinal cord, regulation of the threshold of synaptic plasticity may determine the proneness to undergo sensitization and hyperresponsiveness to noxious input. In the current study, we increased endogenous dopamine levels in the dorsal horn by using re-uptake inhibitor GBR 12935. During the so-induced hyperdopaminergic transmission, conditioning low-frequency (1 Hz) stimulation (LFS) to the sciatic nerve induced long-term potentiation (LTP) of C-fiber-evoked potentials in dorsal horn neurons. The magnitude of LTP was attenuated by blockade of either dopamine D1-like receptors (D1LRs) by with SCH 23390 or NMDA receptor subunit NR2B with antagonist Ro25-6981. Conditioning LFS during GBR 12935 administration increased phosphorylation of dopamine- and cAMP-regulated phosphoprotein of Mr 32kDa (DARPP-32) at threonine 34 residue in synaptosomal (P3) fraction of dorsal horn homogenates, as assessed by Western blot analysis, which was partially prevented by NR2B blockade prior to conditioning stimulation. Conditioning LFS also was followed by higher co-localization of phosphorylated form of NR2B at tyrosine 1472 and pDARPP-32Thr34- with postsynaptic marker PSD-95 in transverse L5 dorsal horn sections. Such increase could be significantly attenuated by D1LR blockade with SCH 23390. The current results support that coincidental endogenous recruitment of D1LRs and NR2B in dorsal horn synapses plays a role in regulating afferent-induced nociceptive plasticity. Parallel increases in DARPP-32 phosphorylation upon LTP induction suggests a role for this phosphoprotein as intracellular detector of convergent D1L- and NMDA receptor activation. PMID:27610622

  1. Spinal high-mobility group box 1 contributes to mechanical allodynia in a rat model of bone cancer pain

    SciTech Connect

    Tong, Wei; Wang, Wei; Huang, Jing; Ren, Ning; Wu, Sheng-Xi; Li, Yong-Qi

    2010-05-14

    Mechanisms underlying bone cancer-induced pain are largely unknown. Previous studies indicate that neuroinflammation in the spinal dorsal horn is especially involved. Being first reported as a nonhistone chromosomal protein, high-mobility group box 1 (HMGB1) is now implicated as a mediator of inflammation. We hypothesized that HMGB1 could trigger the release of cytokines in the spinal dorsal horn and contribute to bone cancer pain. To test this hypothesis, we first built a bone cancer pain model induced by intratibal injection of Walker 256 mammary gland carcinoma cells. The structural damage to the tibia was monitored by radiological analysis. The mechanical allodynia was measured and the expression of spinal HMGB1 and IL-1{beta} was evaluated. We observed that inoculation of cancer cells, but not heat-killed cells, induced progressive bone destruction from 9 d to 21 d post inoculation. Behavioral tests demonstrated that the significant nociceptive response in the cancer cells-injected rats emerged on day 9 and this kind of mechanical allodynia lasted at least 21 d following inoculation. Tumor cells inoculation significantly increased HMGB1 expression in the spinal dorsal horn, while intrathecal injecting a neutralizing antibody against HMGB1 showed an effective and reliable anti-allodynia effect with a dose-dependent manner. IL-1{beta} was significantly increased in caner pain rats while intrathecally administration of anti-HMGB1 could decrease IL-1{beta}. Together with previous reports, we predict that bone cancer induces HMGB1 production, enhancing spinal IL-1{beta} expression and thus modulating spinal excitatory synaptic transmission and pain response.

  2. Somatotopic organization of single primary afferent axon projections to cat spinal cord dorsal horn.

    PubMed

    Brown, P B; Gladfelter, W E; Culberson, J C; Covalt-Dunning, D; Sonty, R V; Pubols, L M; Millecchia, R J

    1991-01-01

    Horseradish peroxidase injection of identified low threshold cutaneous mechanoreceptor (LTCM) primary afferent axons was used to assess the somatotopic organization of hindlimb projections to laminae III and IV of cat dorsal horn. Multiple injections in the same animals were used to assess bilateral symmetry and precision. Thirty-one axons were injected, with more than 1 axon injected in each of 8 animals (25 axons). Somatotopic relations between their receptive field (RF) centers and the centers of their dorsal horn projections were similar to the somatotopic relations between dorsal horn cell RF centers and cell locations. Very few reversals of mediolateral somatotopic gradients (proximodistal RF location as a function of mediolateral projection center) were observed. Two afferents with nearly identical RFs in 1 animal had nearly identical projections. These observations held for many different combinations of receptor types. A simple mathematical model was used to demonstrate that assembly of dorsal horn cell RFs via passive sampling of the presynaptic neuropil by dorsal horn cell dendrites cannot account for the sizes of dorsal horn cell LTCM RFs. Hypothesized mechanisms for assembly of dorsal horn cell RFs must take into account the functional selectivity of connections required to produce RFs smaller than those predicted by the passive assembly model. PMID:1702466

  3. Role of the potassium chloride cotransporter isoform 2-mediated spinal chloride homeostasis in a rat model of visceral hypersensitivity.

    PubMed

    Tang, Dong; Qian, Ai-Hua; Song, Dan-Dan; Ben, Qi-Wen; Yao, Wei-Yan; Sun, Jing; Li, Wei-Guang; Xu, Tian-Le; Yuan, Yao-Zong

    2015-05-01

    Visceral hypersensitivity represents an important hallmark in the pathophysiology of irritable bowel syndrome (IBS), of which the mechanisms remain elusive. The present study was designed to examine whether cation-chloride cotransporter (CCC)-mediated chloride (Cl(-)) homeostasis of the spinal cord is involved in chronic stress-induced visceral hypersensitivity. Chronic visceral hypersensitivity was induced by exposing male Wistar rats to water avoidance stress (WAS). RT-PCR, Western blotting, and immunohistochemistry were used to assess the expression of CCCs in the spinal cord. Patch-clamp recordings were performed on adult spinal cord slices to evaluate Cl(-) homeostasis and Cl(-) extrusion capacity of lamina I neurons. Visceral sensitivity was estimated by measuring the abdominal withdrawal reflex in response to colorectal distension (CRD). After 10 days of WAS exposure, levels of both total protein and the oligomeric form of the K(+)-Cl(-) cotransporter isoform 2 (KCC2), but not Na(+)-K(+)-2Cl(-) transporter isoform 1 (NKCC1), were significantly decreased in the dorsal horn of the lumbosacral spinal cord. The downregulation of KCC2 resulted in a depolarizing shifted equilibrium potential of GABAergic inhibitory postsynaptic current and impaired Cl(-) extrusion capacity in lamina I neurons of the lumbosacral spinal cord from WAS rats. Acute noxious CRD disrupted spinal KCC2 expression and function 2 h after the final distention in sham rats, but not in WAS rats. Pharmacological blockade of KCC2 activity by intrathecal injection of a KCC2 inhibitor [(dihydroindenyl)oxy] alkanoic acid enhanced visceral nociceptive sensitivity in sham rats, but not in WAS rats. These results suggest that KCC2 downregulation-mediated impairment of spinal cord Cl(-) homeostasis may play an important role in chronic stress-induced visceral hypersensitivity. PMID:25792562

  4. Schwann cell myelination of the myelin deficient rat spinal cord following X-irradiation

    SciTech Connect

    Duncan, I.D.; Hammang, J.P.; Gilmore, S.A.

    1988-01-01

    The myelin-deficient (md) rat is an X-linked myelin mutant that has an abnormality of oligodendrocytes and a severe paucity of myelin throughout the CNS. This lack of myelin makes it an ideal model in which to study the cellular interactions that occur when foreign myelinating cells are induced in the milieu of this nonmyelinated CNS. In this study, Schwann cells were induced in the lumbosacral spinal cord by exposing it to radiation, a technique demonstrated repeatedly in other nonmutant strains of rats. Md rats and their age-matched littermates were irradiated (3,000 to 4,000 R) at 3 days of age and perfused 16-22 days later after pulse labeling with tritiated thymidine. In the md rat, Schwann cell invasion progressed from the area of the spinal cord-nerve root junction and extended into the dorsal columns and adjacent gray matter. Autoradiographic evidence revealed that many of these cells incorporated 3H-thymidine, indicating that they were undergoing proliferation. Ultrastructural observations showed that there was an integration of these intraspinal Schwann cells with the cells normally occurring in this environment, i.e., oligodendrocytes and astrocytes. The extent of migration and division of Schwann cells, as well as their interactions with glial cells, were similar to those seen in the nonmutant irradiated littermates. These studies provide conclusive evidence that md rat axons are normal with respect to their ability to provide trophic and mitogenic signals to myelinating cells.

  5. Distribution of cortical neurons projecting to dorsal column nuclear complex and spinal cord in the hedgehog tenrec, Echinops telfairi.

    PubMed

    Künzle, H; Rehkämper, G

    1992-01-01

    Using retrograde axonal flow and wheatgerm agglutinin conjugated to horseradish peroxidase, we studied the distribution of cortical neurons giving rise to spinal and dorsal column nuclear projections, and correlated the regions involved in the projections with the cytoarchitectonic areas recently identified in the lesser hedgehog tenrec, Echinops telfairi (Insectivora). Labeled cortical neurons were most numerous following injections of tracer into higher cervical segments, whereas almost none were found following thoracic injections. The cortical labeling appeared more prominent ipsilaterally than contralaterally after spinal injections, although it was more prominent on the contralateral side after injection into the dorsal column nuclear complex. The majority of labeled neurons found in lamina V occupied the neocortex adjacent to the interhemispheric fissure along the rostrocaudal extent of the small corpus callosum. This location corresponded to an intermediate rostrocaudal portion of the hemisphere, and particularly to area 2 of Rehkämper. In some cases, adjacent portions of areas 1 and 3 were also involved, as well as neocortical regions of the lateral hemisphere. The present data did not suggest a somatotopic organization of the projections; likewise, evidence for the presence of more than one somatosensorimotor representation was sparse. PMID:1414117

  6. Anatomical and Functional Outcomes following a Precise, Graded, Dorsal Laceration Spinal Cord Injury in C57BL/6 Mice

    PubMed Central

    Hill, Rachel L.; Zhang, Yi Ping; Burke, Darlene A.; DeVries, William H.; Zhang, Yongjie; Magnuson, David S.K.; Whittemore, Scott R.

    2009-01-01

    Abstract To study the pathophysiology of spinal cord injury (SCI), we used the LISA-Vibraknife to generate a precise and reproducible dorsal laceration SCI in the mouse. The surgical procedure involved a T9 laminectomy, dural resection, and a spinal cord laceration to a precisely controlled depth. Four dorsal hemisection injuries with lesion depths of 0.5, 0.8, 1.1, and 1.4 mm, as well as normal, sham (laminectomy and dural removal only), and transection controls were examined. Assessments including the Basso Mouse Scale (BMS), footprint analysis, beam walk, toe spread reflex, Hargreaves' test, and transcranial magnetic motor-evoked potential (tcMMEP) analysis were performed to assess motor, sensorimotor, and sensory function. These outcome measures demonstrated significant increases in functional deficits as the depth of the lesion increased, and significant behavioral recovery was observed in the groups over time. Quantitative histological examination showed significant differences between the injury groups and insignificant lesion depth variance within each of the groups. Statistically significant differences were additionally found in the amount of ventral spared tissue at the lesion site between the injury groups. This novel, graded, reproducible laceration SCI model can be used in future studies to look more closely at underlying mechanisms that lead to functional deficits following SCI, as well as to determine the efficacy of therapeutic intervention strategies in the injury and recovery processes following SCI. PMID:19196178

  7. Anatomical and functional outcomes following a precise, graded, dorsal laceration spinal cord injury in C57BL/6 mice.

    PubMed

    Hill, Rachel L; Zhang, Yi Ping; Burke, Darlene A; Devries, William H; Zhang, Yongjie; Magnuson, David S K; Whittemore, Scott R; Shields, Christopher B

    2009-01-01

    To study the pathophysiology of spinal cord injury (SCI), we used the LISA-Vibraknife to generate a precise and reproducible dorsal laceration SCI in the mouse. The surgical procedure involved a T9 laminectomy, dural resection, and a spinal cord laceration to a precisely controlled depth. Four dorsal hemisection injuries with lesion depths of 0.5, 0.8, 1.1, and 1.4 mm, as well as normal, sham (laminectomy and dural removal only), and transection controls were examined. Assessments including the Basso Mouse Scale (BMS), footprint analysis, beam walk, toe spread reflex, Hargreaves' test, and transcranial magnetic motor-evoked potential (tcMMEP) analysis were performed to assess motor, sensorimotor, and sensory function. These outcome measures demonstrated significant increases in functional deficits as the depth of the lesion increased, and significant behavioral recovery was observed in the groups over time. Quantitative histological examination showed significant differences between the injury groups and insignificant lesion depth variance within each of the groups. Statistically significant differences were additionally found in the amount of ventral spared tissue at the lesion site between the injury groups. This novel, graded, reproducible laceration SCI model can be used in future studies to look more closely at underlying mechanisms that lead to functional deficits following SCI, as well as to determine the efficacy of therapeutic intervention strategies in the injury and recovery processes following SCI. PMID:19196178

  8. Electrophysiological characterization of activation state-dependent Ca(v)2 channel antagonist TROX-1 in spinal nerve injured rats.

    PubMed

    Patel, R; Rutten, K; Valdor, M; Schiene, K; Wigge, S; Schunk, S; Damann, N; Christoph, T; Dickenson, A H

    2015-06-25

    Prialt, a synthetic version of Ca(v)2.2 antagonist ω-conotoxin MVIIA derived from Conus magus, is the first clinically approved voltage-gated calcium channel blocker for refractory chronic pain. However, due to the narrow therapeutic window and considerable side effects associated with systemic dosing, Prialt is only administered intrathecally. N-triazole oxindole (TROX-1) is a novel use-dependent and activation state-selective small-molecule inhibitor of Ca(v)2.1, 2.2 and 2.3 calcium channels designed to overcome the limitations of Prialt. We have examined the neurophysiological and behavioral effects of blocking calcium channels with TROX-1. In vitro, TROX-1, in contrast to state-independent antagonist Prialt, preferentially inhibits Ca(v)2.2 currents in rat dorsal root ganglia (DRG) neurons under depolarized conditions. In vivo electrophysiology was performed to record from deep dorsal horn lamina V/VI wide dynamic range neurons in non-sentient spinal nerve-ligated (SNL) and sham-operated rats. In SNL rats, spinal neurons exhibited reduced responses to innocuous and noxious punctate mechanical stimulation of the receptive field following subcutaneous administration of TROX-1, an effect that was absent in sham-operated animals. No effect was observed on neuronal responses evoked by dynamic brushing, heat or cold stimulation in SNL or sham rats. The wind-up response of spinal neurons following repeated electrical stimulation of the receptive field was also unaffected. Spinally applied TROX-1 dose dependently inhibited mechanically evoked neuronal responses in SNL but not sham-operated rats, consistent with behavioral observations. This study confirms the pathological state-dependent actions of TROX-1 through a likely spinal mechanism and reveals a modality selective change in calcium channel function following nerve injury. PMID:25839150

  9. Electrophysiological characterization of activation state-dependent Cav2 channel antagonist TROX-1 in spinal nerve injured rats

    PubMed Central

    Patel, R.; Rutten, K.; Valdor, M.; Schiene, K.; Wigge, S.; Schunk, S.; Damann, N.; Christoph, T.; Dickenson, A.H.

    2015-01-01

    Prialt, a synthetic version of Cav2.2 antagonist ω-conotoxin MVIIA derived from Conus magus, is the first clinically approved voltage-gated calcium channel blocker for refractory chronic pain. However, due to the narrow therapeutic window and considerable side effects associated with systemic dosing, Prialt is only administered intrathecally. N-triazole oxindole (TROX-1) is a novel use-dependent and activation state-selective small-molecule inhibitor of Cav2.1, 2.2 and 2.3 calcium channels designed to overcome the limitations of Prialt. We have examined the neurophysiological and behavioral effects of blocking calcium channels with TROX-1. In vitro, TROX-1, in contrast to state-independent antagonist Prialt, preferentially inhibits Cav2.2 currents in rat dorsal root ganglia (DRG) neurons under depolarized conditions. In vivo electrophysiology was performed to record from deep dorsal horn lamina V/VI wide dynamic range neurons in non-sentient spinal nerve-ligated (SNL) and sham-operated rats. In SNL rats, spinal neurons exhibited reduced responses to innocuous and noxious punctate mechanical stimulation of the receptive field following subcutaneous administration of TROX-1, an effect that was absent in sham-operated animals. No effect was observed on neuronal responses evoked by dynamic brushing, heat or cold stimulation in SNL or sham rats. The wind-up response of spinal neurons following repeated electrical stimulation of the receptive field was also unaffected. Spinally applied TROX-1 dose dependently inhibited mechanically evoked neuronal responses in SNL but not sham-operated rats, consistent with behavioral observations. This study confirms the pathological state-dependent actions of TROX-1 through a likely spinal mechanism and reveals a modality selective change in calcium channel function following nerve injury. PMID:25839150

  10. Reorganization of somatosensory cortical areas 3b and 1 after unilateral section of dorsal columns of the spinal cord in squirrel monkeys

    PubMed Central

    Qi, H-X; Chen, L. M.; Kaas, J.H.

    2011-01-01

    An incomplete lesion of the ascending afferents from the hand in the dorsal columns of the spinal cord in monkeys is followed after weeks of recovery by a reactivation of much of the territory of the hand representations in primary somatosensory cortex (area 3b). However, the relationship between the extent of the dorsal column lesion and the amount of cortical reactivation has not been clear. Largely, this is due to the uncertainties about axon sparing after spinal cord lesions. Here, we unilaterally sectioned dorsal column afferents in the cervical spinal cord (C4-C6) in adult squirrel monkeys. After weeks of recovery, cholera toxin subunit B (CTB) was injected into the distal phalanges to label normal and surviving afferents to the cuneate nuclei representing the hands. Days later, the responsiveness of neurons in cortical areas 3b and 1 to tactile stimulation on the hand was evaluated in a microelectrode mapping session. The sizes and densities of CTB-labeled patches in the cuneate nuclei of both sides were quantified and compared. The results indicate that extensive reactivations of the hand representations in cortical areas 3b and 1 occur contralateral to the spinal cord lesion, even when less than 1% of labeled dorsal column terminations in the cuneate nucleus remained. These results raise the possibilities that secondary afferents from innervated neurons in the spinal cord contribute to the reactivation, and that the reactivation of area 1 is not completely dependent on inputs from area 3b. PMID:21940457

  11. Breathing patterns after mid-cervical spinal contusion in rats

    PubMed Central

    Golder, FJ; Fuller, DD; Lovett-Barr, MR; Vinit, S; Resnick, DK; Mitchell, GS

    2011-01-01

    Respiratory failure is the leading cause of death after cervical spinal injury. We hypothesized that incomplete cervical spinal injuries would alter respiratory pattern and initiate plasticity in the neural control of breathing. Further, we hypothesized that the severity of cervical spinal contusion would correlate with changes in breathing pattern. Fourteen days after C4–C5 contusions, respiratory frequency and tidal volume were measured in unanesthetized Sprague Dawley rats in a whole body plethysmograph. Phrenic motor output was monitored in the same rats which were anesthetized, vagotomized, paralyzed and ventilated to eliminate and/or control sensory feedback that could alter breathing patterns. The extent of spinal injury was approximated histologically by measurements of the injury-induced cyst area in transverse sections; cysts ranged from 2 to 28% of spinal cross-sectional area, and had a unilateral bias. In unanesthetized rats, the severity of spinal injury correlated negatively with tidal volume (R2=0.85; p<0.001) and positively with breathing frequency (R2=0.65; p<0.05). Thus, the severity of C4–C5 spinal contusion dictates post-injury breathing pattern. In anesthetized rats, phrenic burst amplitude was decreased on the side of injury, and burst frequency correlated negatively with contusion size (R2=0.51; p<0.05). A strong correlation between unanesthetized breathing pattern and the pattern of phrenic bursts in anesthetized, vagotomized and ventilated rats suggests that changes in respiratory motor output after spinal injury reflect, at least in part, intrinsic neural mechanisms of CNS plasticity initiated by injury. PMID:21683697

  12. A physiological study of the prenatal development of cutaneous sensory inputs to dorsal horn cells in the rat.

    PubMed Central

    Fitzgerald, M

    1991-01-01

    1. The response of fetal dorsal horn cells to natural and electrical stimulation of the skin of the hindpaw was recorded in vivo from the lumbar spinal cord of anaesthetized rat fetuses still in contact with their mother via the maternal circulation. 2. Responses to electrical stimulation were obtained from embryonic day 17 (E17) but spikes were not evoked by natural skin stimulation until embryonic day 19 (E19). 3. At E19 responses were evoked by pressure or pinching the skin, but responses to low intensity brush and touch were not clear until E20. 4. Receptive fields were small and response amplitudes and frequencies initially very low. However, by E20 bursts of up to fifty spikes were recorded to a single pinch and some cells displayed responses that outlasted the stimulus by 10-15 s. 5. The development of dorsal horn cutaneous evoked spike activity and consequently the ability to transmit cutaneous sensory information to the brain therefore occurs some 2 days after the development of peripheral afferent receptive fields. It is concluded that this represents the maturation time for central synaptic connections. PMID:1886065

  13. Inhibition of opioid release in the rat spinal cord by α2C adrenergic receptors

    PubMed Central

    Chen, Wenling; Song, Bingbing; Marvizón, Juan Carlos G.

    2008-01-01

    Neurotransmitter receptors that control the release of opioid peptides in the spinal cord may play an important role in pain modulation. Norepinephrine, released by a descending pathway originating in the brainstem, is a powerful inducer of analgesia in the spinal cord. Adrenergic α2C receptors are present in opioid-containing terminals in the dorsal horn, where they could modulate opioid release. The goal of this study was to investigate this possibility. Opioid release was evoked from rat spinal cord slices by incubating them with the sodium channel opener veratridine in the presence of peptidase inhibitors (actinonin, captopril and thiorphan), and was measured in situ through the internalization of μ-opioid receptors in dorsal horn neurons. Veratridine produced internalization in 70% of these neurons. The α2 receptor agonists clonidine, guanfacine, medetomidine and UK-14304 inhibited the evoked μ-opioid receptor internalization with IC50s of 1.7 μM, 248 nM, 0.3 nM and 22 nM, respectively. However, inhibition by medetomidine was only partial, and inhibition by UK-14304 reversed itself at concentrations higher than 50 nM. None of these agonists inhibited μ-opioid receptor internalization produced by endomorphin-2, showing that they inhibited opioid release and not the internalization itself. The inhibition produced by clonidine, guanfacine or UK-14304 was completely reversed by the selective α2C antagonist JP-1203. In contrast, inhibition by guanfacine was not prevented by the α2A antagonist BRL-44408. These results show that α2C receptors inhibit the release of opioids in the dorsal horn. This action may serve to shut down the opioid system when the adrenergic system is active. PMID:18343461

  14. The majority of dorsal spinal cord gastrin releasing peptide is synthesized locally whereas neuromedin B is highly expressed in pain- and itch-sensing somatosensory neurons

    PubMed Central

    2012-01-01

    Background Itch is one of the major somatosensory modalities. Some recent findings have proposed that gastrin releasing peptide (Grp) is expressed in a subset of dorsal root ganglion (DRG) neurons and functions as a selective neurotransmitter for transferring itch information to spinal cord interneurons. However, expression data from public databases and earlier literatures indicate that Grp mRNA is only detected in dorsal spinal cord (dSC) whereas its family member neuromedin B (Nmb) is highly expressed in DRG neurons. These contradictory results argue that a thorough characterization of the expression of Grp and Nmb is warranted. Findings Grp mRNA is highly expressed in dSC but is barely detectable in DRGs of juvenile and adult mice. Anti-bombesin serum specifically recognizes Grp but not Nmb. Grp is present in a small number of small-diameter DRG neurons and in abundance in layers I and II of the spinal cord. The reduction of dSC Grp after dorsal root rhizotomy is significantly different from those of DRG derived markers but similar to that of a spinal cord neuronal marker. Double fluorescent in situ of Nmb and other molecular markers indicate that Nmb is highly and selectively expressed in nociceptive and itch-sensitive DRG neurons. Conclusion The majority of dSC Grp is synthesized locally in dorsal spinal cord neurons. On the other hand, Nmb is highly expressed in pain- and itch-sensing DRG neurons. Our findings provide direct anatomic evidence that Grp could function locally in the dorsal spinal cord in addition to its roles in DRG neurons and that Nmb has potential roles in nociceptive and itch-sensitive neurons. These results will improve our understanding about roles of Grp and Nmb in mediating itch sensation. PMID:22776446

  15. Erector Spinal Muscular Schwannoma of the Dorsal Ramus Nerve: A Case Report

    PubMed Central

    Kim, Jeong Hoon; Kim, Chang Hyun; Moon, Jae Gon; Lee, Ho Kook

    2015-01-01

    We present a rare case of intramuscular schwannoma originating from the dorsal ramus nerve in a 62-year-old woman. The mass grew slowly, with pain developing upon touch five years prior. No neurological deficit was detected. The mass was observed in the erector spinae muscles in magnetic resonance imaging (MRI), and surgical excision was performed. The mass was well encapsulated with clear margin. The lesion appeared to originate from the cranial side. We completely removed the mass including the origin. Histopathology confirmed a schwannoma diagnosis. This is the first report, to our knowledge, of a dorsal ramus-nerve schwannoma within the erector spinae muscles. PMID:26512285

  16. Dorsal root ganglia microenvironment of female BB Wistar diabetic rats with mild neuropathy.

    PubMed

    Zochodne, D W; Ho, L T; Allison, J A

    1994-12-01

    Abnormalities in the microenvironment of dorsal root ganglia (DRG) might play a role in the pathogenesis of sensory abnormalities in human diabetic neuropathy. We examined aspects of DRG microenvironment by measuring local blood flow and oxygen tension in the L4 dorsal root ganglia of female BB Wistar (BBW) diabetic rats with mild neuropathy. The findings were compared with concurrent measurements of local sciatic endoneurial blood flow and oxygen tension. Diabetic rats were treated with insulin and underwent electrophysiological, blood flow and oxygen tension measurements at either 7-11 or 17-23 weeks after the development of glycosuria. Nondiabetic female BB Wistar rats from the same colony served as controls. At both ages, BBW diabetic rats had significant abnormalities in sensory, but not motor conduction compared to nondiabetic controls. Sciatic endoneurial blood flow in the diabetic rats of both ages was similar to control values, but the older (17-23 week diabetic) BBW diabetic rats had a selective reduction in DRG blood flow. Sciatic endoneurial oxygen tensions were not significantly altered in the diabetic rats. DRG oxygen tension appeared lowered in younger (7-11 week diabetic) but not older (17-23 week diabetic) BBW rats. Our findings indicate that there are important changes in the DRG microenvironment of diabetic rats with selective sensory neuropathy. PMID:7699389

  17. The Role of Spinal Dopaminergic Transmission in the Analgesic Effect of Nefopam on Rat Inflammatory Pain

    PubMed Central

    Kim, Do Yun; Chae, Joo Wung; Lim, Chang Hun; Heo, Bong Ha; Park, Keun Suk; Lee, Hyung Gon; Choi, Jeong Il; Yoon, Myung Ha

    2016-01-01

    Background Nefopam has been known as an inhibitor of the reuptake of monoamines, and the noradrenergic and/or serotonergic system has been focused on as a mechanism of its analgesic action. Here we investigated the role of the spinal dopaminergic neurotransmission in the antinociceptive effect of nefopam administered intravenously or intrathecally. Methods The effects of intravenously and intrathecally administered nefopam were examined using the rat formalin test. Then we performed a microdialysis study to confirm the change of extracellular dopamine concentration in the spinal dorsal horn by nefopam. To determine whether the changes of dopamine level are associated with the nefopam analgesia, its mechanism was investigated pharmacologically via pretreatment with sulpiride, a dopaminergic D2 receptor antagonist. Results When nefopam was administered intravenously the flinching responses in phase I of the formalin test were decreased, but not those in phase II of the formalin test were decreased. Intrathecally injected nefopam reduced the flinching responses in both phases of the formalin test in a dose dependent manner. Microdialysis study revealed a significant increase of the level of dopamine in the spinal cord by intrathecally administered nefopam (about 3.8 fold the baseline value) but not by that administered intravenously. The analgesic effects of intrathecally injected nefopam were not affected by pretreatment with sulpiride, and neither were those of the intravenous nefopam. Conclusions Both the intravenously and intrathecally administered nefopam effectively relieved inflammatory pain in rats. Nefopam may act as an inhibitor of dopamine reuptake when delivered into the spinal cord. However, the analgesic mechanism of nefopam may not involve the dopaminergic transmission at the spinal level. PMID:27413481

  18. In vivo characterization of colorectal and cutaneous inputs to lumbosacral dorsal horn neurons in the mouse spinal cord.

    PubMed

    Farrell, K E; Rank, M M; Keely, S; Brichta, A M; Graham, B A; Callister, R J

    2016-03-01

    Chronic abdominal pain is a common symptom of inflammatory bowel disease and often persists in the absence of gut inflammation. Although the mechanisms responsible for ongoing pain are unknown, clinical and preclinical evidence suggests lumbosacral spinal cord dorsal horn neurons contribute to these symptoms. At present, we know little about the intrinsic and synaptic properties of this population of neurons in either normal or inflammed conditions. Therefore, we developed an in vivo preparation to make patch-clamp recordings from superficial dorsal horn (SDH) neurons receiving colonic inputs in naïve male mice. Recordings were made in the lumbosacral spinal cord (L6-S1) under isoflurane anesthesia. Noxious colorectal distension (CRD) was used to determine whether SDH neurons received inputs from mechanical stimulation/distension of the colon. Responses to hind paw/tail cutaneous stimulation and intrinsic and synaptic properties were also assessed, as well as action potential discharge properties. Approximately 11% of lumbosacral SDH neurons in the cohort of neurons sampled responded to CRD and a majority of these responses were subthreshold. Most CRD-responsive neurons (80%) also responded to cutaneous stimuli, compared with <50% of CRD-non-responsive neurons. Furthermore, CRD-responsive neurons had more hyperpolarized resting membrane potentials, larger rheobase currents, and reduced levels of excitatory drive, compared to CRD-non-responsive neurons. Our results demonstrate that CRD-responsive neurons can be distinguished from CRD-non-responsive neurons by several differences in their membrane properties and excitatory synaptic inputs. We also demonstrate that SDH neurons with colonic inputs show predominately subthreshold responses to CRD and exhibit a high degree of viscerosomatic convergence. PMID:26708745

  19. Regulation of Neurotrophin-3 and Interleukin-1β and Inhibition of Spinal Glial Activation Contribute to the Analgesic Effect of Electroacupuncture in Chronic Neuropathic Pain States of Rats

    PubMed Central

    Tu, Wenzhan; Wang, Wansheng; Xi, Haiyan; He, Rong; Gao, Liping; Jiang, Songhe

    2015-01-01

    Growing evidence indicates that neurotrophin-3, interleukin-1β, and spinal glia are involved in neuropathic pain derived from dorsal root ganglia to spinal cord. Electroacupuncture is widely accepted to treat chronic pain, but the precise mechanism underlying the analgesic effect of EA has not been fully demonstrated. In this study, the mechanical withdrawal threshold and thermal withdrawal latency were recorded. We used immunofluorescence and western blots methods to investigate the effect of EA on the expression of NT-3 and IL-1β in DRG and spinal cord of CCI rats; we also examined the expression of spinal GFAP and OX-42 in spinal cord. In present study, the MWT and TWL of CCI group rats were lower than those in the Sham CCI group rats, but EA treatment increased the pain thresholds. Furtherly, we found that EA upregulates the expression of NT-3 in DRG and spinal cord of CCI rats, while EA downregulates the expression of IL-1β. Additionally, immunofluorescence exhibited that CCI-induced activation of microglia and astrocytes was inhibited significantly by EA treatment. These results demonstrated that the analgesic effect of EA may be achieved through promoting the neural protection of NT-3 as well as the inhibition of IL-1β production and spinal glial activity. PMID:26161124

  20. GLT1 overexpression reverses established neuropathic pain-related behavior and attenuates chronic dorsal horn neuron activation following cervical spinal cord injury.

    PubMed

    Falnikar, Aditi; Hala, Tamara J; Poulsen, David J; Lepore, Angelo C

    2016-03-01

    Development of neuropathic pain occurs in a major portion of traumatic spinal cord injury (SCI) patients, resulting in debilitating and often long-term physical and psychological burdens. Following SCI, chronic dysregulation of extracellular glutamate homeostasis has been shown to play a key role in persistent central hyperexcitability of superficial dorsal horn neurons that mediate pain neurotransmission, leading to various forms of neuropathic pain. Astrocytes express the major CNS glutamate transporter, GLT1, which is responsible for the vast majority of functional glutamate uptake, particularly in the spinal cord. In our unilateral cervical contusion model of mouse SCI that is associated with ipsilateral forepaw heat hypersensitivity (a form of chronic at-level neuropathic pain-related behavior), we previously reported significant and long-lasting reductions in GLT1 expression and functional GLT1-mediated glutamate uptake in cervical spinal cord dorsal horn. To therapeutically address GLT1 dysfunction following cervical contusion SCI, we injected an adeno-associated virus type 8 (AAV8)-Gfa2 vector into the superficial dorsal horn to increase GLT1 expression selectively in astrocytes. Compared to both contusion-only animals and injured mice that received AAV8-eGFP control injection, AAV8-GLT1 delivery increased GLT1 protein expression in astrocytes of the injured cervical spinal cord dorsal horn, resulting in a significant and persistent reversal of already-established heat hypersensitivity. Furthermore, AAV8-GLT1 injection significantly reduced expression of the transcription factor and marker of persistently increased neuronal activation, ΔFosB, in superficial dorsal horn neurons. These results demonstrate that focal restoration of GLT1 expression in the superficial dorsal horn is a promising target for treating chronic neuropathic pain following SCI. PMID:26496514

  1. Severe burn injury induces a characteristic activation of extracellular signal-regulated kinase 1/2 in spinal dorsal horn neurons.

    PubMed

    White, John P M; Ko, Chin Wing; Fidalgo, Antonio Rei; Cibelli, Mario; Paule, Cleoper C; Anderson, Peter J; Cruz, Celia; Gomba, Szabolcs; Matesz, Klara; Veress, Gabor; Avelino, Antonio; Nagy, Istvan

    2011-08-01

    We have studied scalding-type burn injury-induced activation of extracellular signal-regulated kinase 1/2 (ERK1/2) in the spinal dorsal horn, which is a recognised marker for spinal nociceptive processing. At 5min after severe scalding injury to mouse hind-paw, a substantial number of phosphorylated ERK1/2 (pERK1/2) immunopositive neurons were found in the ipsilateral dorsal horn. At 1h post-injury, the number of pERK1/2-labelled neurons remained substantially the same. However, at 3h post-injury, a further increase in the number of labelled neurons was found on the ipsilateral side, while a remarkable increase in the number of labelled neurons on the contralateral side resulted in there being no significant difference between the extent of the labelling on both sides. By 6h post-injury, the number of labelled neurons was reduced on both sides without there being significant difference between the two sides. A similar pattern of severe scalding injury-induced activation of ERK1/2 in spinal dorsal horn neurons over the same time-course was found in mice which lacked the transient receptor potential type 1 receptor (TRPV1) except that the extent to which ERK1/2 was activated in the ipsilateral dorsal horn at 5 min post-injury was significantly greater in wild-type animals when compared to TRPV1 null animals. This difference in activation of ERK1/2 in spinal dorsal horn neurons was abolished within 1h after injury, demonstrating that TRPV1 is not essential for the maintenance of ongoing spinal nociceptive processing in inflammatory pain conditions in mouse resulting from at least certain types of severe burn injury. PMID:21371920

  2. Immunostaining for Homer reveals the majority of excitatory synapses in laminae I-III of the mouse spinal dorsal horn.

    PubMed

    Gutierrez-Mecinas, Maria; Kuehn, Emily D; Abraira, Victoria E; Polgár, Erika; Watanabe, Masahiko; Todd, Andrew J

    2016-08-01

    The spinal dorsal horn processes somatosensory information before conveying it to the brain. The neuronal organization of the dorsal horn is still poorly understood, although recent studies have defined several distinct populations among the interneurons, which account for most of its constituent neurons. All primary afferents, and the great majority of neurons in laminae I-III are glutamatergic, and a major factor limiting our understanding of the synaptic circuitry has been the difficulty in identifying glutamatergic synapses with light microscopy. Although there are numerous potential targets for antibodies, these are difficult to visualize with immunocytochemistry, because of protein cross-linking following tissue fixation. Although this can be overcome by antigen retrieval methods, these lead to difficulty in detecting other antigens. The aim of this study was to test whether the postsynaptic protein Homer can be used to reveal glutamatergic synapses in the dorsal horn. Immunostaining for Homer gave punctate labeling when viewed by confocal microscopy, and this was restricted to synapses at the ultrastructural level. We found that Homer puncta were colocalized with the AMPA receptor GluR2 subunit, but not with the inhibitory synapse-associated protein gephyrin. We also examined several populations of glutamatergic axons and found that most boutons were in contact with at least one Homer punctum. These results suggest that Homer antibodies can be used to reveal the great majority of glutamatergic synapses without antigen retrieval. This will be of considerable value in tracing synaptic circuits, and also in investigating plasticity of glutamatergic synapses in pain states. PMID:27185486

  3. Antinociceptive effect of ambroxol in rats with neuropathic spinal cord injury pain.

    PubMed

    Hama, Aldric T; Plum, Ann Woodhouse; Sagen, Jacqueline

    2010-12-01

    Symptoms of neuropathic spinal cord injury (SCI) pain include evoked cutaneous hypersensitivity and spontaneous pain, which can be present below the level of the injury. Adverse side-effects obtained with currently available analgesics complicate effective pain management in SCI patients. Voltage-gated Na(+) channels expressed in primary afferent nociceptors have been identified to mediate persistent hyperexcitability in dorsal root ganglia (DRG) neurons, which in part underlies the symptoms of nerve injury-induced pain. Ambroxol has previously demonstrated antinociceptive effects in rat chronic pain models and has also shown to potently block Na(+) channel current in DRG neurons. Ambroxol was tested in rats that underwent a mid-thoracic spinal cord compression injury. Injured rats demonstrated robust hind paw (below-level) heat and mechanical hypersensitivity. Orally administered ambroxol significantly attenuated below-level hypersensitivity at doses that did not affect performance on the rotarod test. Intrathecal injection of ambroxol did not ameliorate below-level hypersensitivity. The current data suggest that ambroxol could be effective for clinical neuropathic SCI pain. Furthermore, the data suggest that peripherally expressed Na(+) channels could lend themselves as targets for the development of pharmacotherapies for SCI pain. PMID:20732348

  4. Antinociceptive effect of ambroxol in rats with neuropathic spinal cord injury pain

    PubMed Central

    Hama, Aldric T.; Plum, Ann Woodhouse; Sagen, Jacqueline

    2010-01-01

    Symptoms of neuropathic spinal cord injury (SCI) pain include evoked cutaneous hypersensitivity and spontaneous pain, which can be present below the level of the injury. Adverse side-effects obtained with currently available analgesics complicate effective pain management in SCI patients. Voltage-gated Na+ channels expressed in primary afferent nociceptors have been identified to mediate persistent hyperexcitability in dorsal root ganglia (DRG) neurons, which in part underlies the symptoms of nerve injury-induced pain. Ambroxol has previously demonstrated antinociceptive effects in rat chronic pain models and has also shown to potently block Na+ channel current in DRG neurons. Ambroxol was tested in rats that underwent a mid-thoracic spinal cord compression injury. Injured rats demonstrated robust hind paw (below-level) heat and mechanical hypersensitivity. Orally administered ambroxol significantly attenuated below-level hypersensitivity at doses that did not affect performance on the rotarod test. Intrathecal injection of ambroxol did not ameliorate below-level hypersensitivity. The current data suggest that ambroxol could be effective for clinical neuropathic SCI pain. Furthermore, the data suggests that peripherally expressed Na+ channels could lend themselves as targets for the development of pharmacotherapies for SCI pain. PMID:20732348

  5. Spinal estrogen receptor alpha mediates estradiol-induced pronociception in a visceral pain model in the rat.

    PubMed

    Ji, Yaping; Tang, Bin; Traub, Richard J

    2011-05-01

    We previously reported that 17β-estradiol (E2) is pronociceptive in a visceral pain model in the rat. Subcutaneously (s.c.) administered E2 reversed the decrease in the colorectal distention (CRD)-evoked visceromotor response produced by ovariectomy (OVx) and CRD-induced nociceptive responses were greater in proestrous rats compared with met/diestrous rats. The site of action, the type of estrogen receptors activated, and the possible intracellular signaling pathway involved are yet to be established. In the present study, intrathecal (i.t.) E2 administered to OVx rats mimicked the effects of s.c. E2, suggesting that spinal estrogen receptors are involved. This is further supported by the observations that the anti-estrogen ICI 182,780 injected i.t. in intact female rats significantly decreased the visceromotor response to CRD, the response of colonic afferents was not affected by OVx, and colonic afferents did not label for estrogen receptor α (ERα). The ERα selective agonist, 4,4',4''-[4-propyl-(1H)-pyrazole-1,3,5-triyl]tris-phenol (PPT; s.c. or i.t.) facilitated the visceromotor response similar to E2, suggesting ERα activation is involved in mediating the pronociceptive effect of E2. PPT (s.c. or i.t.) increased the response of spinal dorsal horn neurons to CRD, indicating a spinal site of action. In addition, s.c. E2 or PPT increased CRD-induced spinal extracellular signal-regulated kinase (ERK) phosphorylation that was not observed in OVx rats and a mitogen-activated protein kinase (MAPK) kinase (MEK) inhibitor blocked facilitation of the visceromotor response by PPT. Taken together, the present study demonstrates that spinal ERα mediates the pronociceptive effect of E2 on visceral signal processing through activation of the MAPK pathway. PMID:21392887

  6. Neuroprotective effects of lactation against kainic acid treatment in the dorsal hippocampus of the rat.

    PubMed

    Vanoye-Carlo, América; Morales, Teresa; Ramos, Eugenia; Mendoza-Rodríguez, Adriana; Cerbón, Marco

    2008-01-01

    Marked hippocampal changes in response to excitatory amino acid agonists occur during pregnancy (e.g. decreased frequency in spontaneous recurrent seizures in rats with KA lesions of the hippocampus) and lactation (e.g. reduced c-Fos expression in response to N-methyl-d,l-aspartic acid but not to kainic acid). In this study, the possibility that lactation protects against the excitotoxic damage induced by KA in hippocampal areas was explored. We compared cell damage induced 24 h after a single systemic administration of KA (5 or 7.5 mg/kg bw) in regions CA1, CA3, and CA4 of the dorsal hippocampus of rats in the final week of lactation to that in diestrus phase. To determine cellular damage in a rostro-caudal segment of the dorsal hippocampus, we used NISSL and Fluorojade staining, immunohistochemistry for active caspase-3 and TUNEL, and we observed that the KA treatment provoked a significant loss of neurons in diestrus rats, principally in the pyramidal cells of CA1 region. In contrast, in lactating rats, pyramidal neurons from CA1, CA3, and CA4 in the dorsal hippocampus were significantly protected against KA-induced neuronal damage, indicating that lactation may be a natural model of neuroprotection. PMID:17963758

  7. Spinal Cord Dopamine D2/D3 Receptors: In Vivo and Ex Vivo Imaging in the Rat using 18F/11C-Fallypride

    PubMed Central

    Kaur, Jasmeet; Khararjian, Armen; Coleman, Robert A.; Constantinescu, Cristian C.; Pan, Min-Liang; Mukherjee, Jogeshwar

    2014-01-01

    Objectives Spinal cord is known to be innervated with dopaminergic cells with catecholaminergic projections arising from the medulla and pons and dopaminergic transmission in the spinal cord is vital for sensory and motor function. Our goal was to evaluate and compare the imaging capability of dopamine D2/D3 receptors in the rat spinal cord using PET ligands 18F-fallypride and 11C-fallypride. Methods Male Sprague-Dawley rats were used in all in vitro and in vivo studies. Spinal cord and brain sections were used for in vitro autoradiography and ex vivo autoradiography. For in vivo studies animals received a 18F-fallypride scan or a 11C-fallypride PET scan. The spinal cord and the brain were then harvested, flash-frozen and imaged ex vivo. For in vivo analysis Logan plots with cerebellum as a reference was used to evaluate binding potentials (BP). Tissue ratios were used for ex vivo analysis. Drug effects were evaluated using clozapine, haloperidol and dopamine were evaluated on spinal cord sections in vitro. Results In vitro studies showed 18F-fallypride binding to superficial dorsal horn (SDH), dorsal horn (DH), ventral horn (VH) and the pars centralis (PC). In the cervical section, the greatest amount of binding appeared to be in the SDH. Ex vivo studies showed approximately 6% of 18F-fallypride in SDH compared to that observed in the striatum. In vivo analysis of both 18F-fallypride and 11C-fallypride in the spinal cord were comparable to that in the extrastriatal regions. Haloperidol and clozapine displaced more than 75% of the 18F-fallypride in spinal cord sections. Conclusions Our studies showed 18F-fallypride and 11C-fallypride binding in the spinal cord in vitro and in vivo. The binding pattern correlates well with the known distribution of dopamine D2/D3 receptors in the spinal cord. PMID:25199843

  8. Overexpression of the dopamine D3 receptor in the rat dorsal striatum induces dyskinetic behaviors.

    PubMed

    Cote, Samantha R; Chitravanshi, Vineet C; Bleickardt, Carina; Sapru, Hreday N; Kuzhikandathil, Eldo V

    2014-04-15

    L-DOPA-induced dyskinesias (LID) are motor side effects associated with treatment of Parkinson's disease (PD). The etiology of LID is not clear; however, studies have shown that the dopamine D3 receptor is upregulated in the basal ganglia of mice, rats and non-human primate models of LID. It is not known if the upregulation of D3 receptor is a cause or result of LID. In this paper we tested the hypothesis that overexpression of the dopamine D3 receptor in dorsal striatum, in the absence of dopamine depletion, will elicit LID. Replication-deficient recombinant adeno-associated virus-2 expressing the D3 receptor or enhanced green fluorescent protein (EGFP) were stereotaxically injected, unilaterally, into the dorsal striatum of adult rats. Post-hoc immunohistochemical analysis revealed that ectopic expression of the D3 receptor was limited to neurons near the injection sites in the dorsal striatum. Following a 3-week recovery period, rats were administered saline, 6 mg/kg L-DOPA, 0.1 mg/kg PD128907 or 10 mg/kg ES609, i.p., and motor behaviors scored. Rats overexpressing the D3 receptor specifically exhibited contralateral axial abnormal involuntary movements (AIMs) following administration of L-DOPA and PD128907 but not saline or the novel agonist ES609. Daily injection of 6 mg/kg L-DOPA to the rats overexpressing the D3 receptor also caused increased vacuous chewing behavior. These results suggest that overexpression of the D3 receptor in the dorsal striatum results in the acute expression of agonist-induced axial AIMs and chronic L-DOPA-induced vacuous chewing behavior. Agonists such as ES609 might provide a novel therapeutic approach to treat dyskinesia. PMID:24462727

  9. Spinal Cord Transection-Induced Allodynia in Rats – Behavioral, Physiopathological and Pharmacological Characterization

    PubMed Central

    M'Dahoma, Saïd; Bourgoin, Sylvie; Kayser, Valérie; Barthélémy, Sandrine; Chevarin, Caroline; Chali, Farah; Orsal, Didier; Hamon, Michel

    2014-01-01

    In humans, spinal cord lesions induce not only major motor and neurovegetative deficits but also severe neuropathic pain which is mostly resistant to classical analgesics. Better treatments can be expected from precise characterization of underlying physiopathological mechanisms. This led us to thoroughly investigate (i) mechanical and thermal sensory alterations, (ii) responses to acute treatments with drugs having patent or potential anti-allodynic properties and (iii) the spinal/ganglion expression of transcripts encoding markers of neuronal injury, microglia and astrocyte activation in rats that underwent complete spinal cord transection (SCT). SCT was performed at thoracic T8–T9 level under deep isoflurane anaesthesia, and SCT rats were examined for up to two months post surgery. SCT induced a marked hyper-reflexia at hindpaws and strong mechanical and cold allodynia in a limited (6 cm2) cutaneous territory just rostral to the lesion site. At this level, pressure threshold value to trigger nocifensive reactions to locally applied von Frey filaments was 100-fold lower in SCT- versus sham-operated rats. A marked up-regulation of mRNAs encoding ATF3 (neuronal injury) and glial activation markers (OX-42, GFAP, P2×4, P2×7, TLR4) was observed in spinal cord and/or dorsal root ganglia at T6-T11 levels from day 2 up to day 60 post surgery. Transcripts encoding the proinflammatory cytokines IL-1β, IL-6 and TNF-α were also markedly but differentially up-regulated at T6–T11 levels in SCT rats. Acute treatment with ketamine (50 mg/kg i.p.), morphine (3–10 mg/kg s.c.) and tapentadol (10–20 mg/kg i.p.) significantly increased pressure threshold to trigger nocifensive reaction in the von Frey filaments test, whereas amitriptyline, pregabalin, gabapentin and clonazepam were ineffective. Because all SCT rats developed long lasting, reproducible and stable allodynia, which could be alleviated by drugs effective in humans, thoracic cord transection might be a

  10. Primary afferents with TRPM8 and TRPA1 profiles target distinct subpopulations of rat superficial dorsal horn neurones

    PubMed Central

    Wrigley, Paul J; Jeong, Hyo-Jin; Vaughan, Christopher W

    2009-01-01

    Background and purpose: The transient receptor potential (TRP) channels, transient receptor potential melastatin-1 (TRPM8) and transient receptor potential ankyrin-1 (TRPA1), are expressed in subpopulations of sensory neurones and have been proposed to mediate innocuous and noxious cold sensation respectively. The aim of this study was to compare TRPM8 and TRPA1 modulation of glutamatergic afferent transmission within the spinal dorsal horn. Experimental approach: Whole cell patch clamp recordings were made from rat spinal cord slices in vitro to examine the effect of TRP agonists and temperature on glutamatergic excitatory postsynaptic currents (EPSCs). Key results: Icilin (3 or 100 µmol·L−1), menthol (200 µmol·L−1) and capsaicin (1 µmol·L−1) reduced the amplitude of primary afferent evoked EPSCs in subpopulations of lamina I and II neurones. In a subpopulation of superficial neurones, innocuous cold (threshold 29°C), 3 µmol·L−1 icilin (EC50 1.5 µmol·L−1) and menthol (EC50 263 µmol·L−1) increased the rate of spontaneous miniature EPSCs. In the majority of lamina I and II neurones, 100 µmol·L−1 icilin (EC50 79 µmol·L−1), allyl isothiocyanate (EC50 226 µmol·L−1), cinnamaldehyde (EC50 38 µmol·L−1) and capsaicin (1 µmol·L−1) increased miniature EPSC rate. The response to 100 µmol·L−1, but not 3 µmol·L−1 icilin, was abolished by ruthenium red, while neither was affected by iodoresiniferatoxin. Responsiveness to 3 µmol·L−1, but not to 100 µmol·L−1 icilin, was highly predictive of innocuous cold responsiveness. Neurones responding to 3 µmol·L−1 icilin and innocuous cold were located more superficially than those responding to 100 µmol·L−1 icilin. Conclusions and implications: Activation of TRPM8 and TRPA1 presynaptically modulated glutamatergic transmission onto partially overlapping but distinct populations of superficial dorsal horn neurones. Spinal TRPM8 and TRPA1 channels may therefore provide

  11. Vitamin A Deficiency Induces Congenital Spinal Deformities in Rats

    PubMed Central

    Li, Zheng; Shen, Jianxiong; Wu, William Ka Kei; Wang, Xiaojuan; Liang, Jinqian; Qiu, Guixing; Liu, Jiaming

    2012-01-01

    Most cases of congenital spinal deformities were sporadic and without strong evidence of heritability. The etiology of congenital spinal deformities is still elusive and assumed to be multi-factorial. The current study seeks to elucidate the effect of maternal vitamin A deficiency and the production of congenital spinal deformities in the offsping. Thirty two female rats were randomized into two groups: control group, which was fed a normal diet; vitamin A deficient group, which were given vitamin A-deficient diet from at least 2 weeks before mating till delivery. Three random neonatal rats from each group were killed the next day of parturition. Female rats were fed an AIN-93G diet sufficient in vitamin A to feed the rest of neonates for two weeks until euthanasia. Serum levels of vitamin A were assessed in the adult and filial rats. Anteroposterior (AP) spine radiographs were obtained at week 2 after delivery to evaluate the presence of the skeletal abnormalities especially of spinal deformities. Liver and vertebral body expression of retinaldehyde dehydrogenase (RALDHs) and RARs mRNA was assessed by reverse transcription-real time PCR. VAD neonates displayed many skeletal malformations in the cervical, thoracic, the pelvic and sacral and limbs regions. The incidence of congenital scoliosis was 13.79% (8/58) in the filial rats of vitamin A deficiency group and 0% in the control group. Furthermore, vitamin A deficiency negatively regulate the liver and verterbral body mRNA levels of RALDH1, RALDH2, RALDH3, RAR-α, RAR-β and RAR-γ. Vitamin A deficiency in pregnancy may induce congenital spinal deformities in the postnatal rats. The decreases of RALDHs and RARs mRNA expression induced by vitamin A deprivation suggest that vertebral birth defects may be caused by a defect in RA signaling pathway during somitogenesis. PMID:23071590

  12. Neuroprotective Effect of Ginsenoside Rd in Spinal Cord Injury Rats.

    PubMed

    Cong, Lin; Chen, Wenting

    2016-08-01

    In this study, the neuroprotective effects of ginsenoside Rd (GS Rd) were evaluated in a rat model of spinal cord injury (SCI). Rats in SCI groups received a T8 laminectomy and a spinal contusion injury. GS Rd 12.5, 25 and 50 mg/kg were administered intraperitoneally 1 hr before the surgery and once daily for 14 days. Dexamethasone 1 mg/kg was administered as a positive control. Locomotor function was evaluated using the BBB score system. H&E staining and Nissl staining were performed to observe the histological changes in the spinal cord. The levels of MDA and GSH and the activity of SOD were assessed to reflect the oxidative stress state. The production of TNF-α, IL-1β and IL-1 was assessed using ELISA kits to examine the inflammatory responses in the spinal cord. TUNEL staining was used to detect the cell apoptosis in the spinal cord. Western blot analysis was used to examine the expression of apoptosis-associated proteins and MAPK proteins. The results demonstrated that GS Rd 25 and 50 mg/kg significantly improved the locomotor function of rats after SCI, reduced tissue injury and increased neuron survival in the spinal cord. Mechanically, GS Rd decreased MDA level, increased GSH level and SOD activity, reduced the production of pro-inflammatory cytokines and prevented cell apoptosis. The effects were equivalent to those of dexamethasone. In addition, GS Rd effectively inhibited the activation of MAPK signalling pathway induced by SCI, which might be involved in the protective effects of GS Rd against SCI. In conclusion, GS Rd attenuates SCI-induced secondary injury through reversing the redox-state imbalance, inhibiting the inflammatory response and apoptosis in the spinal cord tissue. PMID:26833867

  13. Chronic Contusion Spinal Cord Injury Impairs Ejaculatory Reflexes in Male Rats: Partial Recovery by Systemic Infusions of Dopamine D3 Receptor Agonist 7OHDPAT.

    PubMed

    Kozyrev, Natalie; Staudt, Michael D; Brown, Arthur; Coolen, Lique M

    2016-05-15

    Chronic spinal cord injury (SCI) causes major disruption of ejaculatory function in men. Ejaculation is a reflex and the spinal generator for ejaculatory reflexes in the rat has been located in the lumbosacral spinal cord. The effects of SCI on the rat spinal ejaculation generator and ejaculatory reflexes remain understudied. The first goal of the current study was to establish the effects of chronic SCI on the function of the spinal ejaculation generator. Male rats received a contusion injury of the spinal cord at spinal level T6-T7. Ejaculatory reflexes elicited by electrical stimulation of the dorsal penile nerve (DPN) were evaluated in injured and control rats at 4-6 weeks following SCI. SCI males demonstrated significant reductions in bursting of the bulbocavernosus muscle (BCM), an indicator for expulsion phase of ejaculation, and in seminal vesicle pressure (SVP) increases, an indicator for the emission phase of ejaculation, following DPN stimulation. Thus, contusion SCI resulted in long-term impairment of ejaculatory reflexes. The D3 agonist 7-hydroxy-2-(di-N-propylamino) tetralin (7OHDPAT) facilitates ejaculation in spinal cord intact rats, thus the second goal of the current study was to test whether subcutaneous infusions of 7OHDPAT can facilitate ejaculatory reflexes in rats with chronic SCI. Male rats received a contusion injury at T6-T7 and effects of systemic administration of 7OHDPAT (1 mg/kg) were tested 4-5 weeks following injury. Results showed that 7OHDPAT administration facilitated ejaculatory reflexes in SCI males with or without DPN stimulation, provided that supraspinal inputs to the lumbar cord were severed by transection just prior to evaluating the reflex. Thus, 7OHDPAT administration in SCI males was able to overcome the detrimental effects of SCI on ejaculatory reflexes. PMID:26437577

  14. Prolonged noxious mechanical stimulation of the rat's tail: responses and encoding properties of dorsal horn neurones.

    PubMed Central

    Cervero, F; Handwerker, H O; Laird, J M

    1988-01-01

    1. Single-unit electrical activity has been recorded from dorsal horn neurones in the sacral (S1-S2) segments of the spinal cord of barbiturate-anaesthetized rats. Fifty-two neurones responding to a manually applied pinch of their receptive fields in the tail were selected. They were subsequently tested for their responses to four successive 2 min pinches at noxious intensities delivered by a feed-back-controlled mechanical device. 2. Neurones were tested with both innocuous (i.e. brushing and stroking) and noxious (i.e. pinching, pin-prick, and in some cases heating about 45 degrees C) stimulation of their cutaneous receptive fields. Three of the tested cells were driven exclusively by innocuous skin stimulation (mechanoreceptive or class 1), thirty-six were driven by both innocuous and noxious skin stimulation (multireceptive or class 2) and thirteen were driven exclusively by noxious skin stimulation (nocireceptive or class 3). 3. All of the multireceptive and nocireceptive neurones responded to the 2 min noxious pinch with an initial phasic discharge followed by sustained firing that showed little evidence of adaptation throughout the stimulus period. The three mechanoreceptive neurones responded to the 2 min noxious pinch with a short discharge at the stimulus onset, but were silent for the remainder of the stimulus period. 4. Thirty-one cells were tested with successive 2 min pinches of 4, 6 and 8 N (and in some cases, a further 4 N pinch) applied at 10 min intervals. Different encoding properties were observed during the sustained part of the neuronal response according to: (i) the afferent fibre input characteristics of the cell; (ii) whether or not the tail had received a test series of pinches earlier in the same experiment. 5. None of the multireceptive cells with only an A-fibre afferent input encoded the stimulus strength. However, the multireceptive cells with both an A- and a C-fibre afferent input and all nocireceptive cells did encode the stimulus

  15. Modulators of Calcium Influx Regulate Membrane Excitability in Rat Dorsal Root Ganglion Neurons

    PubMed Central

    Lirk, Philipp; Poroli, Mark; Rigaud, Marcel; Fuchs, Andreas; Fillip, Patrick; Huang, Chun-Yuan; Ljubkovic, Marko; Sapunar, Damir; Hogan, Quinn

    2009-01-01

    Background Chronic neuropathic pain resulting from neuronal damage remains difficult to treat, in part due to incomplete understanding of underlying cellular mechanisms. We have previously shown that inward Ca2+ flux (ICa) across the sensory neuron plasmalemma is decreased in a rodent model of chronic neuropathic pain, but the direct consequence of this loss of ICa on function of the sensory neuron has not been defined. We therefore examined the extent to which altered membrane properties after nerve injury, especially increased excitability that may contribute to chronic pain, are attributable to diminished Ca2+ entry. Methods Intracellular microelectrode measurements were obtained from A-type neurons of dorsal root ganglia excised from control rats and those with neuropathic pain behavior following spinal nerve ligation. Recording conditions were varied to suppress or promote ICa while biophysical parameters and excitability were determined. Results Both lowered external bath Ca2+ concentration and blockade of ICa with bath cadmium diminished the duration and area of the afterhyperpolarization (AHP), accompanied by decreased current threshold for action potential (AP) initiation and increased repetitive firing during sustained depolarization. Reciprocally, elevated bath Ca2+ increased the AHP and suppressed repetitive firing. Voltage sag during neuronal hyperpolarization, indicative of the cation-nonselective H-current, diminished with lowered bath Ca2+, cadmium application, or chelation of intracellular Ca2+. Additional recordings with selective blockers of ICa subtypes showed that N-, P/Q, L-, and R-type currents each contribute to generation of the AHP, and that blockade of any of these as well as the T-type current slows the AP upstroke, prolongs the AP duration, and (except for L-type current) decreases the current threshold for AP initiation. Conclusions Taken together, our findings show that suppression of ICa decreases the AHP, reduces the

  16. Purinergic signalling in a latent stem cell niche of the rat spinal cord.

    PubMed

    Marichal, Nicolás; Fabbiani, Gabriela; Trujillo-Cenóz, Omar; Russo, Raúl E

    2016-06-01

    The ependyma of the spinal cord harbours stem cells which are activated by traumatic spinal cord injury. Progenitor-like cells in the central canal (CC) are organized in spatial domains. The cells lining the lateral aspects combine characteristics of ependymocytes and radial glia (RG) whereas in the dorsal and ventral poles, CC-contacting cells have the morphological phenotype of RG and display complex electrophysiological phenotypes. The signals that may affect these progenitors are little understood. Because ATP is massively released after spinal cord injury, we hypothesized that purinergic signalling plays a part in this spinal stem cell niche. We combined immunohistochemistry, in vitro patch-clamp whole-cell recordings and Ca(2+) imaging to explore the effects of purinergic agonists on ependymal progenitor-like cells in the neonatal (P1-P6) rat spinal cord. Prolonged focal application of a high concentration of ATP (1 mM) induced a slow inward current. Equimolar concentrations of BzATP generated larger currents that reversed close to 0 mV, had a linear current-voltage relationship and were blocked by Brilliant Blue G, suggesting the presence of functional P2X7 receptors. Immunohistochemistry showed that P2X7 receptors were expressed around the CC and the processes of RG. BzATP also generated Ca(2+) waves in RG that were triggered by Ca(2+) influx and propagated via Ca(2+) release from internal stores through activation of ryanodine receptors. We speculate that the intracellular Ca(2+) signalling triggered by P2X7 receptor activation may be an epigenetic mechanism to modulate the behaviour of progenitors in response to ATP released after injury. PMID:26988236

  17. Persistent at-level thermal hyperalgesia and tactile allodynia accompany chronic neuronal and astrocyte activation in superficial dorsal horn following mouse cervical contusion spinal cord injury.

    PubMed

    Watson, Jaime L; Hala, Tamara J; Putatunda, Rajarshi; Sannie, Daniel; Lepore, Angelo C

    2014-01-01

    In humans, sensory abnormalities, including neuropathic pain, often result from traumatic spinal cord injury (SCI). SCI can induce cellular changes in the CNS, termed central sensitization, that alter excitability of spinal cord neurons, including those in the dorsal horn involved in pain transmission. Persistently elevated levels of neuronal activity, glial activation, and glutamatergic transmission are thought to contribute to the hyperexcitability of these dorsal horn neurons, which can lead to maladaptive circuitry, aberrant pain processing and, ultimately, chronic neuropathic pain. Here we present a mouse model of SCI-induced neuropathic pain that exhibits a persistent pain phenotype accompanied by chronic neuronal hyperexcitability and glial activation in the spinal cord dorsal horn. We generated a unilateral cervical contusion injury at the C5 or C6 level of the adult mouse spinal cord. Following injury, an increase in the number of neurons expressing ΔFosB (a marker of chronic neuronal activation), persistent astrocyte activation and proliferation (as measured by GFAP and Ki67 expression), and a decrease in the expression of the astrocyte glutamate transporter GLT1 are observed in the ipsilateral superficial dorsal horn of cervical spinal cord. These changes have previously been associated with neuronal hyperexcitability and may contribute to altered pain transmission and chronic neuropathic pain. In our model, they are accompanied by robust at-level hyperaglesia in the ipsilateral forepaw and allodynia in both forepaws that are evident within two weeks following injury and persist for at least six weeks. Furthermore, the pain phenotype occurs in the absence of alterations in forelimb grip strength, suggesting that it represents sensory and not motor abnormalities. Given the importance of transgenic mouse technology, this clinically-relevant model provides a resource that can be used to study the molecular mechanisms contributing to neuropathic pain

  18. Intrathecal orphenadrine elicits spinal block in the rat.

    PubMed

    Chen, Yu-Wen; Tzeng, Jann-Inn; Chen, Yu-Chung; Hung, Ching-Hsia; Wang, Jhi-Joung

    2014-11-01

    The purpose of this study was to estimate the local anesthetic effect of orphenadrine, an anti-muscarinic agent, in spinal anesthesia and its comparison with the local anesthetic lidocaine. After the rat was injected intrathecally, the spinal block of orphenadrine and lidocaine was constructed in a dosage-dependent fashion. The potency and duration of spinal anesthesia with orphenadrine were compared with that of lidocaine. Our data demonstrated that orphenadrine and lidocaine elicited dose-dependent spinal blockades on the motor function, sensory, and proprioception. On the 50% effective dose (ED50) basis, the ranks of potency in motor function, nociception, and proprioception were orphenadrine>lidocaine (P<0.01). At equipotent doses (ED25, ED50, ED75), the block duration elicited by orphenadrine was greater than that elicited by lidocaine (P<0.01). Orphenadrine, but not lidocaine, exhibited longer duration of nociceptive/sensory blockade than that of motor blockade at equipotent doses. Ineffective-dose orphenadrine as adjuvant did not enhance spinal anesthesia with lidocaine. The preclinical data revealed that orphenadrine with a more sensory-selective action over motor block exhibited more potent and longer spinal anesthesia when compared to lidocaine. PMID:25205132

  19. Regional differences in radiosensitivity across the rat cervical spinal cord

    SciTech Connect

    Bijl, Hendrik P. . E-mail: h.p.bijl@rt.azg.nl; Luijk, Peter van; Coppes, Rob P.; Schippers, Jacobus M.; Konings, Antonius W.T.; Kogel, Albert J. van der

    2005-02-01

    Purpose: To study regional differences in radiosensitivity within the rat cervical spinal cord. Methods and materials: Three types of inhomogeneous dose distributions were applied to compare the radiosensitivity of the lateral and central parts of the rat cervical spinal cord. The left lateral half of the spinal cord was irradiated with two grazing proton beams, each with a different penumbra (20-80% isodoses): lateral wide (penumbra = 1.1 mm) and lateral tight (penumbra = 0.8 mm). In the third experiment, the midline of the cord was irradiated with a narrow proton beam with a penumbra of 0.8 mm. The irradiated spinal cord length (CT-2) was 20 mm in all experiments. The animals were irradiated with variable single doses of unmodulated protons (150 MeV) with the shoot-through method, whereby the plateau of the depth-dose profile is used rather than the Bragg peak. The endpoint for estimating isoeffective dose (ED{sub 50}) values was paralysis of fore and/or hind limbs within 210 days after irradiation. Histology of the spinal cords was performed to assess the radiation-induced tissue damage. Results: High-precision proton irradiation of the lateral or the central part of the spinal cord resulted in a shift of dose-response curves to higher dose values compared with the homogeneously irradiated cervical cord to the same 20-mm length. The ED{sub 50} values were 28.9 Gy and 33.4 Gy for the lateral wide and lateral tight irradiations, respectively, and as high as 71.9 Gy for the central beam experiment, compared with 20.4 Gy for the homogeneously irradiated 20-mm length of cervical cord. Histologic analysis of the spinal cords showed that the paralysis was due to white matter necrosis. The radiosensitivity was inhomogeneously distributed across the spinal cord, with a much more radioresistant central white matter (ED{sub 50} = 71.9 Gy) compared with lateral white matter (ED{sub 50} values = 28.9 Gy and 33.4 Gy). The gray matter did not show any noticeable lesions, such

  20. Optogenetic Inhibition of Dorsal Medial Prefrontal Cortex Attenuates Stress-Induced Reinstatement of Palatable Food Seeking in Female Rats

    PubMed Central

    Calu, Donna J.; Kawa, Alex B.; Marchant, Nathan J.; Navarre, Brittany M.; Henderson, Mark J.; Chen, Billy; Yau, Hau-Jie; Bossert, Jennifer M.; Schoenbaum, Geoffrey; Deisseroth, Karl; Harvey, Brandon K.; Hope, Bruce T.; Shaham, Yavin

    2013-01-01

    Relapse to maladaptive eating habits during dieting is often provoked by stress. Recently, we identified a role of dorsal medial prefrontal cortex (mPFC) neurons in stress-induced reinstatement of palatable food seeking in male rats. It is unknown whether endogenous neural activity in dorsal mPFC drives stress-induced reinstatement in female rats. Here, we used an optogenetic approach, in which female rats received bilateral dorsal mPFC microinjections of viral constructs coding light-sensitive eNpHR3.0 – eYFP or control eYFP protein and intracranial fiber optic implants. Rats were food restricted and trained to lever press for palatable food pellets. Subsequently, pellets were removed, and lever pressing was extinguished; then the effect of bilateral dorsal mPFC light delivery on reinstatement of food seeking was assessed after injections of the pharmacological stressor yohimbine (an α-2 andrenoceptor antagonist) or pellet priming, a manipulation known to provoke food seeking in hungry rats. Dorsal mPFC light delivery attenuated yohimbine-induced reinstatement of food seeking in eNpHR3.0-injected but not eYFP-injected rats. This optical manipulation had no effect on pellet-priming-induced reinstatement or ongoing food-reinforced responding. Dorsal mPFC light delivery attenuated yohimbine-induced Fos immuno-reactivity and disrupted neural activity during in vivo electrophysiological recording in awake rats. Optical stimulation caused significant outward currents and blocked electrically evoked action potentials in eNpHR3.0-injected but not eYFP-injected mPFC hemispheres. Light delivery alone caused no significant inflammatory response in mPFC. These findings indicate that intracranial light delivery in eNpHR3.0 rats disrupts endogenous dorsal mPFC neural activity that plays a role in stress-induced relapse to food seeking in female rats. PMID:23283335

  1. Expression of Lymphatic Markers in the Adult Rat Spinal Cord

    PubMed Central

    Kaser-Eichberger, Alexandra; Schroedl, Falk; Bieler, Lara; Trost, Andrea; Bogner, Barbara; Runge, Christian; Tempfer, Herbert; Zaunmair, Pia; Kreutzer, Christina; Traweger, Andreas; Reitsamer, Herbert A.; Couillard-Despres, Sebastien

    2016-01-01

    Under physiological conditions, lymphatic vessels are thought to be absent from the central nervous system (CNS), although they are widely distributed within the rest of the body. Recent work in the eye, i.e., another organ regarded as alymphatic, revealed numerous cells expressing lymphatic markers. As the latter can be involved in the response to pathological conditions, we addressed the presence of cells expressing lymphatic markers within the spinal cord by immunohistochemistry. Spinal cord of young adult Fisher rats was scrutinized for the co-expression of the lymphatic markers PROX1 and LYVE-1 with the cell type markers Iba1, CD68, PGP9.5, OLIG2. Rat skin served as positive control for the lymphatic markers. PROX1-immunoreactivity was detected in many nuclei throughout the spinal cord white and gray matter. These nuclei showed no association with LYVE-1. Expression of LYVE-1 could only be detected in cells at the spinal cord surface and in cells closely associated with blood vessels. These cells were found to co-express Iba1, a macrophage and microglia marker. Further, double labeling experiments using CD68, another marker found in microglia and macrophages, also displayed co-localization in the Iba1+ cells located at the spinal cord surface and those apposed to blood vessels. On the other hand, PROX1-expressing cells found in the parenchyma were lacking Iba1 or PGP9.5, but a significant fraction of those cells showed co-expression of the oligodendrocyte lineage marker OLIG2. Intriguingly, following spinal cord injury, LYVE-1-expressing cells assembled and reorganized into putative pre-vessel structures. As expected, the rat skin used as positive controls revealed classical lymphatic vessels, displaying PROX1+ nuclei surrounded by LYVE-1-immunoreactivity. Classical lymphatics were not detected in adult rat spinal cord. Nevertheless, numerous cells expressing either LYVE-1 or PROX1 were identified. Based on their localization and overlapping expression with

  2. Effects of neonatal capsaicin treatment on descending modulation of spinal nociception from the rostral, medial medulla in adult rat.

    PubMed

    Zhuo, M; Gebhart, G F

    1994-05-01

    Stimulation-produced modulation from the rostral, medial medulla (RMM) on the spinal nociceptive tail-flick (TF) reflex and on lumbar spinal dorsal horn neuron responses to noxious cutaneous stimuli was studied in adult rats treated as neonates with capsaicin or vehicle. In vehicle-treated rats (n = 7), both descending facilitatory and inhibitory influences on the TF reflex were produced from the RMM. At 11/23 sites in the RMM, electrical stimulation produced biphasic modulatory effects. Electrical stimulation facilitated the spinal nociceptive TF reflex at low intensities (5-25 microA) and inhibited the TF reflex at greater intensities (50-200 microA). The mean threshold intensity of stimulation to inhibit the TF reflex (cut-off time = 7.0 s) was 66 microA (n = 11). At 11 of 23 sites, electrical stimulation only inhibited the TF reflex; the mean threshold intensity of stimulation to inhibit the TF reflex was 50 microA (n = 11). At one stimulation site, electrical stimulation only facilitated the TF reflex at the intensities tested (5-100 microA). In capsaicin-treated rats (n = 6), the proportion of sites from which electrical stimulation only inhibited the TF reflex was significantly less (3/27 sites = 11%) than in vehicle-treated rats (11/23 = 48%). The threshold intensity of stimulation to inhibit the TF reflex from these three sites was 50 microA. The number of sites in RMM from which electrical stimulation only facilitated the TF reflex was significantly greater in capsaicin-treated rats (15/27 = 56%) than in vehicle-treated rats (1/23 = 4%). Neither the number of sites in RMM from which electrical stimulation produced biphasic modulatory effects on the TF reflex (48% and 33%, respectively) nor the intensities of stimulation or magnitudes of facilitation or inhibition of the TF reflex significantly differed between vehicle- and capsaicin-treated rats. In electrophysiological experiments, all units studied responded to non-noxious and noxious intensities of

  3. Cognitive impairment and morphological changes in the dorsal hippocampus of very old female rats.

    PubMed

    Morel, G R; Andersen, T; Pardo, J; Zuccolilli, G O; Cambiaggi, V L; Hereñú, C B; Goya, R G

    2015-09-10

    The hippocampus, a medial temporal lobe structure necessary for the formation of spatial memory, is particularly affected by both normal and pathologic aging. In previous studies, we observed a significant age-related increase in dopaminergic neuron loss in the hypothalamus and the substantia nigra of female rats, which becomes more conspicuous at extreme ages. Here, we extend our studies by assessing spatial memory in 4-6 month-old (young), 26-month-old (old) and 29-32-month-old (senile) Sprague-Dawley female rats as well as the age-related histopathological changes in their dorsal hippocampus. Age changes in spatial memory performance were assessed with a modified version of the Barnes maze test. We employed two probe trials (PTs), one and five days after training, respectively, in order to evaluate learning ability as well as short-term and longer-term spatial memory retention. A set of relevant hippocampal cell markers was also quantitated in the animals by means of an unbiased stereological approach. The results revealed that old rats perform better than senile rats in acquisition trials and young rats perform better than both aging groups. However, during short-term PT both aging groups showed a preserved spatial memory while in longer-term PT, spatial memory showed deterioration in both aged groups. Morphological analysis showed a marked decrease (94-97%) in doublecortin neuron number in the dentate gyrus in both aged groups and a reduction in glial fibrillary acidic protein-positive cell number in the stratum radiatum of aging rats. Astroglial process length and branching complexity decreased in aged rats. We conclude that while target-seeking activity and learning ability decrease in aged females, spatial memory only declines in the longer-term tests. The reduction in neuroblast number and astroglial arborescence complexity in the dorsal hippocampus are likely to play a role in the cognitive deficits of aging rats. PMID:26141841

  4. Comparison of dorsal root ganglion gene expression in rat models of traumatic and HIV-associated neuropathic pain

    PubMed Central

    Maratou, Klio; Wallace, Victoria C.J.; Hasnie, Fauzia S.; Okuse, Kenji; Hosseini, Ramine; Jina, Nipurna; Blackbeard, Julie; Pheby, Timothy; Orengo, Christine; Dickenson, Anthony H.; McMahon, Stephen B.; Rice, Andrew S.C.

    2009-01-01

    To elucidate the mechanisms underlying peripheral neuropathic pain in the context of HIV infection and antiretroviral therapy, we measured gene expression in dorsal root ganglia (DRG) of rats subjected to systemic treatment with the anti-retroviral agent, ddC (Zalcitabine) and concomitant delivery of HIV-gp120 to the rat sciatic nerve. L4 and L5 DRGs were collected at day 14 (time of peak behavioural change) and changes in gene expression were measured using Affymetrix whole genome rat arrays. Conventional analysis of this data set and Gene Set Enrichment Analysis (GSEA) was performed to discover biological processes altered in this model. Transcripts associated with G protein coupled receptor signalling and cell adhesion were enriched in the treated animals, while ribosomal proteins and proteasome pathways were associated with gene down-regulation. To identify genes that are directly relevant to neuropathic mechanical hypersensitivity, as opposed to epiphenomena associated with other aspects of the response to a sciatic nerve lesion, we compared the gp120 + ddC-evoked gene expression with that observed in a model of traumatic neuropathic pain (L5 spinal nerve transection), where hypersensitivity to a static mechanical stimulus is also observed. We identified 39 genes/expressed sequence tags that are differentially expressed in the same direction in both models. Most of these have not previously been implicated in mechanical hypersensitivity and may represent novel targets for therapeutic intervention. As an external control, the RNA expression of three genes was examined by RT-PCR, while the protein levels of two were studied using western blot analysis. PMID:18606552

  5. Connections from the rat dorsal column nuclei (DCN) to the periaqueductal gray matter (PAG).

    PubMed

    Barbaresi, Paolo; Mensà, Emanuela

    2016-08-01

    Electrical stimulation of the dorsal columns (DCs; spinal cord stimulation; SCS) has been proposed to treat chronic neuropathic pain. SCS may activate a dual mechanism that would affect both the spinal cord and supraspinal levels. Stimulation of DCs or DC nuclei (DCN) in animals where neuropathic pain has been induced causes activation of brainstem centers including the periaqueductal gray (PAG), which is involved in the endogenous pain suppression system. Biotinylated dextran-amine (BDA) was iontophoretically injected into the DCN to analyze the ascending projection directed to the PAG. Separate injections into the gracile nucleus (GrN) and the cuneate nucleus (CunN) showed BDA-positive fibers terminating in different regions of the contralateral PAG. GrN-PAG afferents terminated in the caudal and middle portions of PAG-l, whereas CunN-PAG fibers terminated in the middle and rostral portions of PAG-l. Based on the DCN somatotopic map, the GrN sends information to the PAG from the contralateral hindlimb and the tail and the CunN from the contralateral forelimb, shoulder, neck and ear. This somatotopic organization is consistent with earlier electrophysiological and PAG stimulation studies. These fibers could form part of the DCs-brainstem-spinal cord loop, which may be involved in the inhibitory effects of SCS on neuropathic pain. PMID:26902642

  6. Upregulation of EMMPRIN (OX47) in Rat Dorsal Root Ganglion Contributes to the Development of Mechanical Allodynia after Nerve Injury

    PubMed Central

    Wang, Qun; Sun, Yanyuan; Ren, Yingna; Gao, Yandong; Tian, Li; Liu, Yang; Pu, Yanan; Gou, Xingchun; Chen, Yanke; Lu, Yan

    2015-01-01

    Matrix metalloproteinases (MMPs) are widely implicated in inflammation and tissue remodeling associated with various neurodegenerative diseases and play an important role in nociception and allodynia. Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) plays a key regulatory role for MMP activities. However, the role of EMMPRIN in the development of neuropathic pain is not clear. Western blotting, real-time quantitative RT-PCR (qRT-PCR), and immunofluorescence were performed to determine the changes of messenger RNA and protein of EMMPRIN/OX47 and their cellular localization in the rat dorsal root ganglion (DRG) after nerve injury. Paw withdrawal threshold test was examined to evaluate the pain behavior in spinal nerve ligation (SNL) model. The lentivirus containing OX47 shRNA was injected into the DRG one day before SNL. The expression level of both mRNA and protein of OX47 was markedly upregulated in ipsilateral DRG after SNL. OX47 was mainly expressed in the extracellular matrix of DRG. Administration of shRNA targeted against OX47 in vivo remarkably attenuated mechanical allodynia induced by SNL. In conclusion, peripheral nerve injury induced upregulation of OX47 in the extracellular matrix of DRG. RNA interference against OX47 significantly suppressed the expression of OX47 mRNA and the development of mechanical allodynia. The altered expression of OX47 may contribute to the development of neuropathic pain after nerve injury. PMID:26697232

  7. Tlx1/3 and Ptf1a control the expression of distinct sets of transmitter and peptide receptor genes in the developing dorsal spinal cord.

    PubMed

    Guo, Zhen; Zhao, Congling; Huang, Menggui; Huang, Tianwen; Fan, Mingran; Xie, Zhiqin; Chen, Ying; Zhao, Xiaolin; Xia, Guannan; Geng, Junlan; Cheng, Leping

    2012-06-20

    Establishing the pattern of expression of transmitters and peptides as well as their receptors in different neuronal types is crucial for understanding the circuitry in various regions of the brain. Previous studies have demonstrated that the transmitter and peptide phenotypes in mouse dorsal spinal cord neurons are determined by the transcription factors Tlx1/3 and Ptf1a. Here we show that these transcription factors also determine the expression of two distinct sets of transmitter and peptide receptor genes in this region. We have screened the expression of 78 receptor genes in the spinal dorsal horn by in situ hybridization. We found that receptor genes Gabra1, Gabra5, Gabrb2, Gria3, Grin3a, Grin3b, Galr1, and Npy1r were preferentially expressed in Tlx3-expressing glutamatergic neurons and their derivatives, and deletion of Tlx1 and Tlx3 resulted in the loss of expression of these receptor genes. Furthermore, we obtained genetic evidence that Tlx3 uses distinct pathways to control the expression of receptor genes. We also found that receptor genes Grm3, Grm4, Grm5, Grik1, Grik2, Grik3, and Sstr2 were mainly expressed in Pax2-expressing GABAergic neurons in the spinal dorsal horn, and their expression in this region was abolished or markedly reduced in Ptf1a and Pax2 deletion mutant mice. Together, our studies indicate that Tlx1/3 and Ptf1a, the key transcription factors for fate determination of glutamatergic and GABAergic neurons in the dorsal spinal cord, are also responsible for controlling the expression of two distinct sets of transmitter and peptide receptor genes. PMID:22723691

  8. Peripheral and central alterations affecting spinal nociceptive processing and pain at adulthood in rats exposed to neonatal maternal deprivation.

    PubMed

    Juif, Pierre-Eric; Salio, Chiara; Zell, Vivien; Melchior, Meggane; Lacaud, Adrien; Petit-Demouliere, Nathalie; Ferrini, Francesco; Darbon, Pascal; Hanesch, Ulrike; Anton, Fernand; Merighi, Adalberto; Lelièvre, Vincent; Poisbeau, Pierrick

    2016-08-01

    The nociceptive system of rodents is not fully developed and functional at birth. Specifically, C fibers transmitting peripheral nociceptive information establish synaptic connections in the spinal cord already during the embryonic period that only become fully functional after birth. Here, we studied the consequences of neonatal maternal deprivation (NMD, 3 h/day, P2-P12) on the functional establishment of C fiber-mediated neurotransmission in spinal cord and of pain-related behavior. In vivo recording revealed that C fiber-mediated excitation of spinal cord neurons could be observed at P14 only in control but not in NMD rats. NMD was associated with a strong alteration in the expression of growth factors controlling C nociceptor maturation as well as two-pore domain K+ channels known to set nociceptive thresholds. In good agreement, C-type sensory neurons from NMD animals appeared to be hypoexcitable but functionally connected to spinal neurons, especially those expressing TRPV1 receptors. In vivo and in vitro recordings of lamina II spinal neurons at P14 revealed that the NMD-related lack of C fiber-evoked responses resulted from an inhibitory barrage in the spinal cord dorsal horn. Eventually, C-type sensory-spinal processing could be recovered after a delay of about 10 days in NMD animals. However, animals remained hypersensitive to noxious stimulus up to P100 and this might be due to an excessive expression of Nav1.8 transcripts in DRG neurons. Together, our data provide evidence for a deleterious impact of perinatal stress exposure on the maturation of the sensory-spinal nociceptive system that may contribute to the nociceptive hypersensitivity in early adulthood. PMID:27285721

  9. Spinal Cord T-Cell Infiltration in the Rat Spared Nerve Injury Model: A Time Course Study

    PubMed Central

    Gattlen, Christophe; Clarke, Christine B.; Piller, Nicolas; Kirschmann, Guylène; Pertin, Marie; Decosterd, Isabelle; Gosselin, Romain-Daniel; Suter, Marc R.

    2016-01-01

    The immune system is involved in the development of neuropathic pain. In particular, the infiltration of T-lymphocytes into the spinal cord following peripheral nerve injury has been described as a contributor to sensory hypersensitivity. We used the spared nerve injury (SNI) model of neuropathic pain in Sprague Dawley adult male rats to assess proliferation, and/or protein/gene expression levels for microglia (Iba1), T-lymphocytes (CD2) and cytotoxic T-lymphocytes (CD8). In the dorsal horn ipsilateral to SNI, Iba1 and BrdU stainings revealed microglial reactivity and proliferation, respectively, with different durations. Iba1 expression peaked at D4 and D7 at the mRNA and protein level, respectively, and was long-lasting. Proliferation occurred almost exclusively in Iba1 positive cells and peaked at D2. Gene expression observation by RT-qPCR array suggested that T-lymphocytes attracting chemokines were upregulated after SNI in rat spinal cord but only a few CD2/CD8 positive cells were found. A pronounced infiltration of CD2/CD8 positive T-cells was seen in the spinal cord injury (SCI) model used as a positive control for lymphocyte infiltration. Under these experimental conditions, we show early and long-lasting microglia reactivity in the spinal cord after SNI, but no lymphocyte infiltration was found. PMID:27005622

  10. Acute Delivery of EphA4-Fc Improves Functional Recovery after Contusive Spinal Cord Injury in Rats

    PubMed Central

    Spanevello, Mark Damien; Tajouri, Sophie Ines; Mirciov, Cornel; Kurniawan, Nyoman; Pearse, Martin John; Fabri, Louis Jerry; Owczarek, Catherine Mary; Hardy, Matthew Philip; Bradford, Rebecca Anne; Ramunno, Melanie Louise; Turnley, Ann Maree; Ruitenberg, Marc Jan

    2013-01-01

    Abstract Blocking the action of inhibitory molecules at sites of central nervous system injury has been proposed as a strategy to promote axonal regeneration and functional recovery. We have previously shown that genetic deletion or competitive antagonism of EphA4 receptor activity promotes axonal regeneration and functional recovery in a mouse model of lateral hemisection spinal cord injury. Here we have assessed the effect of blocking EphA4 activation using the competitive antagonist EphA4-Fc in a rat model of thoracic contusive spinal cord injury. Using a ledged tapered balance beam and open-field testing, we observed significant improvements in recovery of locomotor function after EphA4-Fc treatment. Consistent with functional improvement, using high-resolution ex vivo magnetic resonance imaging at 16.4T, we found that rats treated with EphA4-Fc had a significantly increased cross-sectional area of the dorsal funiculus caudal to the injury epicenter compared with controls. Our findings indicate that EphA4-Fc promotes functional recovery following contusive spinal cord injury and provides further support for the therapeutic benefit of treatment with the competitive antagonist in acute cases of spinal cord injury. PMID:23557244

  11. Distinct forms of synaptic inhibition and neuromodulation regulate calretinin-positive neuron excitability in the spinal cord dorsal horn.

    PubMed

    Smith, K M; Boyle, K A; Mustapa, M; Jobling, P; Callister, R J; Hughes, D I; Graham, B A

    2016-06-21

    The dorsal horn (DH) of the spinal cord contains a heterogenous population of neurons that process incoming sensory signals before information ascends to the brain. We have recently characterized calretinin-expressing (CR+) neurons in the DH and shown that they can be divided into excitatory and inhibitory subpopulations. The excitatory population receives high-frequency excitatory synaptic input and expresses delayed firing action potential discharge, whereas the inhibitory population receives weak excitatory drive and exhibits tonic or initial bursting discharge. Here, we characterize inhibitory synaptic input and neuromodulation in the two CR+ populations, in order to determine how each is regulated. We show that excitatory CR+ neurons receive mixed inhibition from GABAergic and glycinergic sources, whereas inhibitory CR+ neurons receive inhibition, which is dominated by glycine. Noradrenaline and serotonin produced robust outward currents in excitatory CR+ neurons, predicting an inhibitory action on these neurons, but neither neuromodulator produced a response in CR+ inhibitory neurons. In contrast, enkephalin (along with selective mu and delta opioid receptor agonists) produced outward currents in inhibitory CR+ neurons, consistent with an inhibitory action but did not affect the excitatory CR+ population. Our findings show that the pharmacology of inhibitory inputs and neuromodulator actions on CR+ cells, along with their excitatory inputs can define these two subpopulations further, and this could be exploited to modulate discrete aspects of sensory processing selectively in the DH. PMID:27045594

  12. Presynaptic inhibitory effects of fluvoxamine, a selective serotonin reuptake inhibitor, on nociceptive excitatory synaptic transmission in spinal superficial dorsal horn neurons of adult mice.

    PubMed

    Tomoyose, Orie; Kodama, Daisuke; Ono, Hideki; Tanabe, Mitsuo

    2014-01-01

    Fluvoxamine, a selective serotonin (5-HT) reuptake inhibitor, has been shown to exert analgesic effects in humans and laboratory animals. However, its effects on spinal nociceptive synaptic transmission have not been fully characterized. Here, whole-cell recordings were made from dorsal horn neurons in spinal slices with attached dorsal roots from adult mice, and the effects of fluvoxamine on monosynaptic A-fiber- and C-fiber-mediated excitatory postsynaptic currents (EPSCs) evoked in response to electrical stimulation of a dorsal root were studied. Fluvoxamine (10 - 100 μM) concentration-dependently suppressed both monosynaptic A-fiber- and C-fiber-mediated EPSCs, which were attenuated by the selective 5-HT1A receptor antagonist WAY100635. In the presence of the selective 5-HT3 receptor antagonist tropisetron, fluvoxamine hardly suppressed A-fiber-mediated EPSCs, whereas its inhibitory effect on C-fiber-mediated EPSCs was not affected. Although fluvoxamine increased the paired-pulse ratio of A-fiber-mediated EPSCs, it increased the frequency of spontaneous and miniature EPSCs (sEPSCs and mEPSCs). Since sEPSCs and mEPSCs appeared to arise largely from spinal interneurons, we then recorded strontium-evoked asynchronous events occurring after A-fiber stimulation, whose frequency was reduced by fluvoxamine. These results suggest that fluvoxamine reduces excitatory synaptic transmission from primary afferent fibers via presynaptic mechanisms involving 5-HT1A and/or 5-HT3 receptors, which may contribute to its analgesic effects. PMID:25252797

  13. Segmental Neuropathic Pain Does Not Develop in Male Rats with Complete Spinal Transections

    PubMed Central

    Kaddumi, Ezidin G.; Johnson, Richard D.

    2008-01-01

    Abstract In a previous study using male rats, a correlation was found between the development of “at-level” allodynia in T6-7 dermatomes following severe T8 spinal contusion injury and the sparing of some myelinated axons within the core of the lesion epicenter. To further test our hypothesis that this sparing is important for the expression of allodynia and the supraspinal plasticity that ensues, an injury that severs all axons (i.e., a complete spinal cord transection) was made in 15 male rats. Behavioral assessments were done at level throughout the 30-day recovery period followed by terminal electrophysiological recordings (urethane anesthesia) from single medullary reticular formation (MRF) neurons receiving convergent nociceptive inputs from receptive fields above, at, and below the lesion level. None of the rats developed signs of at-level allodynia (versus 18 of 26 male rats following severe contusion). However, the terminal recording (206 MRF neurons) data resembled those obtained previously post-contusion. That is, there was evidence of neuronal hyper-excitability (relative to previous data from intact controls) to high- and low-threshold mechanical stimulation for “at-level” (dorsal trunk) and “above-level” (eyelids and face) cutaneous territories. These results, when combined with prior data on intact controls and severe/moderate contusions, indicate that (1) an anatomically incomplete injury (some lesion epicenter axonal sparing) following severe contusion is likely important for the development of allodynia and (2) the neuronal hyper-excitability at the level of the medulla is likely involved in nociceptive processes that are not directly related to the conscious expression of pain-like avoidance behaviors that are being used as evidence of allodynia. PMID:18986225

  14. Improvements in impaired GABA and GAD65/67 production in the spinal dorsal horn contribute to exercise-induced hypoalgesia in a mouse model of neuropathic pain

    PubMed Central

    Taguchi, MS, Satoru; Tajima, Fumihiro; Senba, Emiko

    2016-01-01

    Background Physical exercise effectively attenuates neuropathic pain, and multiple events including the inhibition of activated glial cells in the spinal dorsal horn, activation of the descending pain inhibitory system, and reductions in pro-inflammatory cytokines in injured peripheral nerves may contribute to exercise-induced hypoalgesia. Since fewer GABAergic hypoalgesic interneurons exist in the dorsal horn in neuropathic pain model animals, the recovery of impaired GABAergic inhibition in the dorsal horn may improve pain behavior. We herein determined whether the production of gamma-aminobutyric acid (GABA) and glutamic acid decarboxylase (GAD) in the dorsal horn is restored by treadmill running and contributes to exercise-induced hypoalgesia in neuropathic pain model mice. C57BL/6 J mice underwent partial sciatic nerve ligation (PSL). PSL-Runner mice ran on a treadmill at 7 m/min for 60 min/day, 5 days/week, from two days after PSL. Results Mechanical allodynia and heat hyperalgesia developed in PSL-Sedentary mice but were significantly attenuated in PSL-Runner mice. PSL markedly decreased GABA and GAD65/67 levels in neuropils in the ipsilateral dorsal horn, while treadmill running inhibited these reductions. GABA+ neuronal nuclei+ interneuron numbers in the ipsilateral dorsal horn were significantly decreased in PSL-Sedentary mice but not in PSL-Runner mice. Pain behavior thresholds positively correlated with GABA and GAD65/67 levels and GABAergic interneuron numbers in the ipsilateral dorsal horns of PSL-Sedentary and -Runner mice. Conclusions Treadmill running prevented PSL-induced reductions in GAD65/67 production, and, thus, GABA levels may be retained in interneurons and neuropils in the superficial dorsal horn. Therefore, improvements in impaired GABAergic inhibition may be involved in exercise-induced hypoalgesia. PMID:27030712

  15. Fos-like immunoreactivity in rat dorsal raphe nuclei induced by alkaloid extract of Mitragyna speciosa.

    PubMed

    Kumarnsit, Ekkasit; Vongvatcharanon, Uraporn; Keawpradub, Niwat; Intasaro, Pranom

    2007-04-12

    Mitragyna speciosa (MS) has been traditionally used for medicinal purposes especially in southern Thailand. Previously, an alkaloid extract of this plant was demonstrated to mediate antinociception, partly, through the descending serotonergic system. The present study investigated the stimulatory effect of the MS extract on the dorsal raphe nucleus and its antidepressant-like activity. The MS extract containing approximately 60% mitragynine as a major indole alkaloid was used to treat the animals. The stimulatory effect of the MS extract was determined by detecting the expression of the immediate early gene, cfos, in the dorsal raphe nucleus of male Wistar rats. The immunohistochemistry was used to detect Fos protein, the protein product of cfos gene. The present data show that a significant increase in Fos expression was observed following long-term administration of the MS extract (40 mg/kg) for 60 consecutive days. In addition, the antidepressant-like activity of the MS extract was determined by using the forced swimming test (FST) in male mice. The results show that a single injection (either 60 or 90 mg/kg doses) significantly decreased immobility time in the FST. These findings indicate that the MS extract has a stimulatory effect on the dorsal raphe nucleus and an antidepressant-like activity. Stimulation of this brain area has been known to cause antinociception. These findings suggest that the MS extract might produce antinociceptive and/or antidepressive actions partly through activation of the dorsal raphe nucleus. Moreover, the dorsal raphe nucleus may be one of site of MS action in the central nervous system. PMID:17316993

  16. Quantitative analysis of hindlimbs locomotion kinematics in spinalized rats treated with Tamoxifen plus treadmill exercise.

    PubMed

    Osuna-Carrasco, L P; López-Ruiz, J R; Mendizabal-Ruiz, E G; De la Torre-Valdovinos, B; Bañuelos-Pineda, J; Jiménez-Estrada, I; Dueñas-Jiménez, S H

    2016-10-01

    Locomotion recovery after a spinal cord injury (SCI) includes axon regeneration, myelin preservation and increased plasticity in propriospinal and descending spinal circuitries. The combined effects of tamoxifen and exercise after a SCI were analyzed in this study to determine whether the combination of both treatments induces the best outcome in locomotion recovery. In this study, the penetrating injury was provoked by a sharp projectile that penetrates through right dorsal and ventral portions of the T13-L1 spinal segments, affecting propriospinal and descending/ascending tracts. Intraperitoneal application of Tamoxifen and a treadmill exercise protocol, as rehabilitation therapies, separately or combined, were used. To evaluate the functional recovery, angular patterns of the hip, knee and ankle joints as well as the leg pendulum-like movement (PLM) were measured during the unrestricted gait of treated and untreated (UT) animals, previously and after the traumatic injury (15 and 30days post-injury (dpi)). A pattern (curve) comparison analysis was made by using a locally designed Matlab script that determines the Frechet dissimilarity. The SCI magnitude was assessed by qualitative and quantitative histological analysis of the injury site 30days after SCI. Our results showed that all treated groups had an improvement in hindlimbs kinematics compared to the UT group, which showed a poor gait locomotion recovery throughout the rehabilitation period. The group with the combined treatment (tamoxifen+exercise (TE)) presented the best outcome. In conclusion, tamoxifen and treadmill exercise treatments are complementary therapies for the functional recovery of gait locomotion in hemi-spinalized rats. PMID:27450566

  17. The role of N-methylaspartate receptors in mediating responses of rat and cat spinal neurones to defined sensory stimuli.

    PubMed

    Headley, P M; Parsons, C G; West, D C

    1987-04-01

    1. Single-cell recordings were made from neurones in various spinal laminae in anaesthetized or decerebrated, spinalized or intact rats and cats. Cells were activated by controlled peripheral sensory stimuli which mimicked natural conditions and with some cells also by micro-electrophoretically administered excitatory amino acid analogues. Such responses were tested with amino acid antagonists administered both micro-electrophoretically and intravenously. 2. With cells in the dorsal horn, the dissociative anaesthetic ketamine, administered either micro-electrophoretically or intravenously at doses which selectively reduce responses to N-methylaspartate, had no consistent effect on any of the sensory responses examined. 3. The non-selective amino acid antagonist cis-2,3-piperidine dicarboxylate was somewhat more effective at reducing sensory responses. 4. With motoneurones, intravenous N-methylaspartate-blocking doses of ketamine consistently reduced nociceptive responses. Non-nociceptive responses were less affected. 5. With ventral horn interneurones, intravenous but not micro-electrophoretic ketamine reduced nociceptive responses on about half the cells tested. 6. These results are interpreted in terms of the physiological role of the N-methylaspartate class of excitatory amino acid receptor in mediating responses in the ventral but not dorsal horn of the spinal cord to peripheral somatic stimuli. PMID:2821241

  18. Dynorphin Acts as a Neuromodulator to Inhibit Itch in the Dorsal Horn of the Spinal Cord

    PubMed Central

    Kardon, Adam P.; Polgár, Erika; Hachisuka, Junichi; Snyder, Lindsey M.; Cameron, Darren; Savage, Sinead; Cai, Xiaoyun; Karnup, Sergei; Fan, Christopher R.; Hemenway, Gregory M.; Bernard, Carcha S.; Schwartz, Erica S.; Nagase, Hiroshi; Schwarzer, Christoph; Watanabe, Masahiko; Furuta, Takahiro; Kaneko, Takeshi; Koerber, H. Richard; Todd, Andrew J.; Ross, Sarah E.

    2014-01-01

    Summary Menthol and other counterstimuli relieve itch, resulting in an antipruritic state that persists for minutes to hours. However, the neural basis for this effect is unclear, and the underlying neuromodulatory mechanisms are unknown. Previous studies revealed that Bhlhb5−/− mice, which lack a specific population of spinal inhibitory interneurons (B5-I neurons), develop pathological itch. Here we characterize B5-I neurons and show that they belong to a neurochemically distinct subset. We provide cause-and-effect evidence that B5-I neurons inhibit itch and show that dynorphin, which is released from B5-I neurons, is a key neuromodulator of pruritus. Finally, we show that B5-I neurons are innervated by menthol-, capsaicin-, and mustard oil-responsive sensory neurons and are required for the inhibition of itch by menthol. These findings provide a cellular basis for the inhibition of itch by chemical counterstimuli and suggest that kappa opioids may be a broadly effective therapy for pathological itch. PMID:24726382

  19. Injury-Dependent and Disability-Specific Lumbar Spinal Gene Regulation following Sciatic Nerve Injury in the Rat.

    PubMed

    Austin, Paul J; Bembrick, Alison L; Denyer, Gareth S; Keay, Kevin A

    2015-01-01

    Allodynia, hyperalgesia and spontaneous pain are cardinal sensory signs of neuropathic pain. Clinically, many neuropathic pain patients experience affective-motivational state changes, including reduced familial and social interactions, decreased motivation, anhedonia and depression which are severely debilitating. In earlier studies we have shown that sciatic nerve chronic constriction injury (CCI) disrupts social interactions, sleep-wake-cycle and endocrine function in one third of rats, a subgroup reliably identified six days after injury. CCI consistently produces allodynia and hyperalgesia, the intensity of which was unrelated either to the altered social interactions, sleep-wake-cycle or endocrine changes. This decoupling of the sensory consequences of nerve injury from the affective-motivational changes is reported in both animal experiments and human clinical data. The sensory changes triggered by CCI are mediated primarily by functional changes in the lumbar dorsal horn, however, whether lumbar spinal changes may drive different affective-motivational states has never been considered. In these studies, we used microarrays to identify the unique transcriptomes of rats with altered social behaviours following sciatic CCI to determine whether specific patterns of lumbar spinal adaptations characterised this subgroup. Rats underwent CCI and on the basis of reductions in dominance behaviour in resident-intruder social interactions were categorised as having Pain & Disability, Pain & Transient Disability or Pain alone. We examined the lumbar spinal transcriptomes two and six days after CCI. Fifty-four 'disability-specific' genes were identified. Sixty-five percent were unique to Pain & Disability rats, two-thirds of which were associated with neurotransmission, inflammation and/or cellular stress. In contrast, 40% of genes differentially regulated in rats without disabilities were involved with more general homeostatic processes (cellular structure

  20. Injury-Dependent and Disability-Specific Lumbar Spinal Gene Regulation following Sciatic Nerve Injury in the Rat

    PubMed Central

    Denyer, Gareth S.; Keay, Kevin A.

    2015-01-01

    Allodynia, hyperalgesia and spontaneous pain are cardinal sensory signs of neuropathic pain. Clinically, many neuropathic pain patients experience affective-motivational state changes, including reduced familial and social interactions, decreased motivation, anhedonia and depression which are severely debilitating. In earlier studies we have shown that sciatic nerve chronic constriction injury (CCI) disrupts social interactions, sleep-wake-cycle and endocrine function in one third of rats, a subgroup reliably identified six days after injury. CCI consistently produces allodynia and hyperalgesia, the intensity of which was unrelated either to the altered social interactions, sleep-wake-cycle or endocrine changes. This decoupling of the sensory consequences of nerve injury from the affective-motivational changes is reported in both animal experiments and human clinical data. The sensory changes triggered by CCI are mediated primarily by functional changes in the lumbar dorsal horn, however, whether lumbar spinal changes may drive different affective-motivational states has never been considered. In these studies, we used microarrays to identify the unique transcriptomes of rats with altered social behaviours following sciatic CCI to determine whether specific patterns of lumbar spinal adaptations characterised this subgroup. Rats underwent CCI and on the basis of reductions in dominance behaviour in resident-intruder social interactions were categorised as having Pain & Disability, Pain & Transient Disability or Pain alone. We examined the lumbar spinal transcriptomes two and six days after CCI. Fifty-four ‘disability-specific’ genes were identified. Sixty-five percent were unique to Pain & Disability rats, two-thirds of which were associated with neurotransmission, inflammation and/or cellular stress. In contrast, 40% of genes differentially regulated in rats without disabilities were involved with more general homeostatic processes (cellular structure

  1. Whole-body vibration induces pain and lumbar spinal inflammation responses in the rat that vary with the vibration profile.

    PubMed

    Zeeman, Martha E; Kartha, Sonia; Winkelstein, Beth A

    2016-08-01

    Whole-body vibration (WBV) is linked epidemiologically to neck and back pain in humans, and to forepaw mechanical allodynia and cervical neuroinflammation in a rodent model of WBV, but the response of the low back and lumbar spine to WBV is unknown. A rat model of WBV was used to determine the effect of different WBV exposures on hind paw behavioral sensitivity and neuroinflammation in the lumbar spinal cord. Rats were exposed to 30 min of WBV at either 8 or 15 Hz on days 0 and 7, with the lumbar spinal cord assayed using immunohistochemistry at day 14. Behavioral sensitivity was measured using mechanical stimulation of the hind paws to determine the onset, persistence, and/or recovery of allodynia. Both WBV exposures induce mechanical allodynia 1 day following WBV, but only the 8 Hz WBV induces a sustained decrease in the withdrawal threshold through day 14. Similarly, increased activation of microglia, macrophages, and astrocytes in the superficial dorsal horn of the lumbar spinal cord is only evident after the painful 8 Hz WBV. Moreover, extracellular signal-regulated kinase (ERK)-phosphorylation is most robust in neurons and astrocytes of the dorsal horn, with the most ERK phosphorylation occurring in the 8 Hz group. These findings indicate that a WBV exposure that induces persistent pain also induces a host of neuroimmune cellular activation responses that are also sustained. This work indicates there is an injury-dependent response that is based on the vibration parameters, providing a potentially useful platform for studying mechanisms of painful spinal injuries. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1439-1446, 2016. PMID:27571442

  2. Vasopressin immunoreactive fibers and neurons in the dorsal pontine tegmentum of the rat, monkey and human.

    PubMed

    Caffé, A R; Holstege, J C; van Leeuwen, F W

    1991-01-01

    It is now well established that extensive extrahypothalamic vasopressin (VP) systems exist in the rat, monkey and human brain. There are marked differences between species, but in each case VP nuclei provide dense afferents to the dorsal pontine tegmentum. Here VP may play a role in the mechanisms exerted by the locus coeruleus (LC) neurons, possibly both as a neurotransmitter and as a neuromodulator. Although we are aware of some properties of VP systems, e.g., gonadal steroid dependency in the rat, major gaps characterize our knowledge of its anatomy. With regard to the interaction of VP with the LC in the brainstem of mammals some of the questions which stand out are: (1) Is VP really being biosynthesized and transported by LC cells and, if not, what is its function within these cells? (2) Is there a structural difference between male and female LC neurons in the rat as a consequence of the sex-dimorphic VP innervation? (3) What is the origin of VP afferents in the dorsal pontine tegmentum of the (non)human primate and are these afferents also controlled by gonadal steroids? Research strategies to answer these questions will provide us with information to resolve some of the current inconsistencies about the anatomy and the function of the VP and LC systems in the brain. PMID:1813922

  3. Reorganization of central terminals of myelinated primary afferents in the rat dorsal horn following peripheral axotomy.

    PubMed

    Woolf, C J; Shortland, P; Reynolds, M; Ridings, J; Doubell, T; Coggeshall, R E

    1995-09-11

    We have investigated the time course and extent to which peripheral nerve lesions cause a morphological reorganization of the central terminals of choleragenoid-horseradish peroxidase (B-HRP)-labelled primary afferent fibers in the mammalian dorsal horn. Choleragenoid-horseradish peroxidase is retrogradely transported by myelinated (A) sensory axons to laminae I, III, IV and V of the normal dorsal horn of the spinal cord, leaving lamina II unlabelled. We previously showed that peripheral axotomy results in the sprouting of numerous B-HRP-labelled large myelinated sensory axons into lamina II. We show here that this spread of B-HRP-labelled axons into lamina II is detectable at 1 week, maximal by 2 weeks and persists for over 6 months postlesion. By 9 months, however, B-HRP fibers no longer appear in lamina II. The sprouting into lamina II occurs whether regeneration is allowed (crush) or prevented (section with ligation), and does not reverse at times when peripheral fibers reinnervate the periphery. We also show that 15 times more synaptic terminals in lamina II are labelled by B-HRP 2 weeks after axotomy than in the normal. We interpret this as indicating that the sprouting fibers are making synaptic contacts with postsynaptic targets. This implies that A-fiber terminal reorganization is a prominent and long-lasting but not permanent feature of peripheral axotomy. We also provide evidence that this sprouting is the consequence of a combination of an atrophic loss of central synaptic terminals and the conditioning of the sensory neurons by peripheral axotomy. The sprouting of large sensory fibers into the spinal territory where postsynaptic targets usually receive only small afferent fiber input may bear on the intractable touch-evoked pain that can follow nerve injury. PMID:7499558

  4. Decoupling Actions from Consequences: Dorsal Hippocampal Lesions Facilitate Instrumental Performance, but Impair Behavioral Flexibility in Rats

    PubMed Central

    Busse, Sebastian; Schwarting, Rainer K. W.

    2016-01-01

    The present study is part of a series of experiments, where we analyze why and how damage of the rat’s dorsal hippocampus (dHC) can enhance performance in a sequential reaction time task (SRTT). In this task, sequences of distinct visual stimulus presentations are food-rewarded in a fixed-ratio-13-schedule. Our previous study (Busse and Schwarting, 2016) had shown that rats with lesions of the dHC show substantially shorter session times and post-reinforcement pauses (PRPs) than controls, which allows for more practice when daily training is kept constant. Since sequential behavior is based on instrumental performance, a sequential benefit might be secondary to that. In order to test this hypothesis in the present study, we performed two experiments, where pseudorandom rather than sequential stimulus presentation was used in rats with excitotoxic dorsal hippocampal lesions. Again, we found enhanced performance in the lesion-group in terms of shorter session times and PRPs. During the sessions we found that the lesion-group spent less time with non-instrumental behavior (i.e., grooming, sniffing, and rearing) after prolonged instrumental training. Also, such rats showed moderate evidence for an extinction impairment under devalued food reward conditions and significant deficits in a response-outcome (R-O)-discrimination task in comparison to a control-group. These findings suggest that facilitatory effects on instrumental performance after dorsal hippocampal lesions may be primarily a result of complex behavioral changes, i.e., reductions of behavioral flexibility and/or alterations in motivation, which then result in enhanced instrumental learning. PMID:27375453

  5. Peripheral inflammation facilitates Abeta fiber-mediated synaptic input to the substantia gelatinosa of the adult rat spinal cord.

    PubMed

    Baba, H; Doubell, T P; Woolf, C J

    1999-01-15

    Whole-cell patch-clamp recordings were made from substantia gelatinosa (SG) neurons in thick adult rat transverse spinal cord slices with attached dorsal roots to study changes in fast synaptic transmission induced by peripheral inflammation. In slices from naive rats, primary afferent stimulation at Abeta fiber intensity elicited polysynaptic EPSCs in only 14 of 57 (25%) SG neurons. In contrast, Abeta fiber stimulation evoked polysynaptic EPSCs in 39 of 62 (63%) SG neurons recorded in slices from rats inflamed by an intraplantar injection of complete Freund's adjuvant (CFA) 48 hr earlier (p < 0.001). Although the peripheral inflammation had no significant effect on the threshold and conduction velocities of Abeta, Adelta, and C fibers recorded in dorsal roots, the mean threshold intensity for eliciting EPSCs was significantly lower in cells recorded from rats with inflammation (naive: 33.2 +/- 15.1 microA, n = 57; inflamed: 22.8 +/- 11.3 microA, n = 62, p < 0.001), and the mean latency of EPSCs elicited by Abeta fiber stimulation in CFA-treated rats was significantly shorter than that recorded from naive rats (3.3 +/- 1.8 msec, n = 36 vs 6.0 +/- 3.5 msec, n = 12; p = 0.010). Abeta fiber stimulation evoked polysynaptic IPSCs in 4 of 25 (16%) cells recorded from naive rat preparations and 14 of 26 (54%) SG neurons from CFA-treated rats (p < 0.001). The mean threshold intensity for IPSCs was also significantly lower in CFA-treated rats (naive: 32.5 +/- 15.7 microA, n = 25; inflamed: 21. 9 +/- 9.9 microA, n = 26, p = 0.013). The facilitation of Abeta fiber-mediated input into the substantia gelatinosa after peripheral inflammation may contribute to altered sensory processing. PMID:9880605

  6. Role of spinal P2Y6 and P2Y11 receptors in neuropathic pain in rats: possible involvement of glial cells

    PubMed Central

    2014-01-01

    Background The participation of spinal P2X receptors in neuropathic pain is well recognized. However, the role of P2Y receptors has been less studied. The purpose of this study was to investigate the contribution of spinal P2Y6,11 receptors following peripheral nerve damage induced by spinal nerve ligation. In addition, we determined the expression of P2Y6,11 receptors in the dorsal spinal cord in presence of the selective P2Y6,11 receptors antagonists. Furthermore, we evaluated the participation of spinal microglia and astrocytes in the pronociceptive role of P2Y6,11 receptors. Results Spinal administration of the selective P2Y6 (MRS2578, 10–100 μM) and P2Y11 (NF340, 0.3–30 μM) receptor antagonists reduced tactile allodynia in spinal nerve ligated rats. Nerve injury increased the expression of P2Y6,11 receptors at 7, 14 and 21 days after injury. Furthermore, intrathecal administration of MRS2578 (100 μM/day) and NF340 (30 μM/day) for 3 days significantly reduced spinal nerve injury-induced increase in P2Y6,11 receptors expression, respectively. Spinal treatment (on day 14 after injury) with minocycline (100 μg/day) or fluorocitrate (1 nmol/day) for 7 days reduced tactile allodynia and spinal nerve injury-induced up-regulation in Iba-1 and GFAP, respectively. In addition, minocycline reduced nerve injury-induced up-regulation in P2Y6,11 receptors whereas that fluorocitrate diminished P2Y11, but not P2Y6, receptors up-regulation. Intrathecal treatment (on day 21 after injury) with the selective P2Y6 (PSB0474, 3–30 μM) and P2Y11 (NF546, 1–10 μM) receptor agonists produced remarkable tactile allodynia in nerve ligated rats previously treated with minocycline or fluorocitrate for 7 days. Conclusions Our data suggest that spinal P2Y6 is present in spinal microglia while P2Y11 receptors are present in both spinal microglia and astrocytes, and both receptors are up-regulated in rats subjected to spinal nerve injury. In addition, our data suggest

  7. Increased responsiveness of rat dorsal horn neurons in vivo following prolonged intrathecal exposure to interferon-gamma.

    PubMed

    Vikman, K S; Siddall, P J; Duggan, A W

    2005-01-01

    Prolonged increases in the level of the pro-inflammatory cytokine interferon-gamma occur in the CNS during some disease states associated with persistent pain. Administration of interferon-gamma to both humans and rodents has produced pain or pain-related behavior but the underlying mechanisms are unknown. The present study examined the effects of repeated intrathecal administration of interferon-gamma on dorsal horn neuronal responses under in vivo conditions. In addition, behavioral effects of interferon-gamma treatment were studied. Intrathecal cannulae were implanted into anesthetized rats. Animals then received either 1000 U of recombinant rat interferon-gamma in 10 microl buffer intrathecally, repeated four times over 8 days, or similarly administered buffer (controls). Interferon-gamma-treated animals showed a significant reduction in paw withdrawal threshold to mechanical stimulation of the hind paw. Electrophysiological experiments were performed under halothane anesthesia. Extracellular recordings of spontaneous and evoked responses were obtained from dorsal horn neurons (n=64) in the lumbar spinal cord. There was a significantly higher proportion of spontaneously active neurons in the interferon-gamma-treated animals (50%) when compared with controls (19%). A significantly increased proportion of neurons from interferon-gamma-treated animals displayed afterdischarges following both innocuous and noxious mechanical stimulation of the receptive field (brush: 21% in interferon-gamma-treated, 3% in controls; pinch: 97% in interferon-gamma-treated, 50% in controls). Neurons from interferon-gamma-treated animals also showed significantly increased wind-up of action potentials in response to repeated electrical stimulation of the sciatic nerve at C-fiber strength at both 0.5 and 1 Hz. Paired-pulse inhibition, evoked through electrical stimulation of the cutaneous receptive field, was significantly decreased in neurons from interferon-gamma-treated animals at 50

  8. Anterograde labeling of ventrolateral funiculus pathways with spinal enlargement connections in the adult rat spinal cord

    PubMed Central

    Reed, William R.; Shum-Siu, Alice; Whelan, Ashley; Onifer, Stephen M.; Magnuson, David S.K.

    2009-01-01

    The ventrolateral funiculus in the spinal cord has been identified as containing important ascending and descending pathways related to locomotion and interlimb coordination. The purpose of this descriptive study was to investigate the patterns of axon termination of long ascending and descending ventrolateral pathways within the cervical and lumbar enlargements of the adult rat spinal cord. To accomplish this, we made discrete unilateral injections of the tracer biotinylated dextran-amine (BDA) into the ventrolateral white matter at T9. Although some BDA-labeled axons with varicosities were found bilaterally at all cervical levels, particularly dense BDA-labeling was observed in laminae VIII and IX ipsilaterally at the C6 and C8 levels. In the same animals, dense terminal labeling was found in the lumbar enlargement in medial lamina VII and ventromedial laminae VIII and IX contralaterally. This labeling was most apparent in the more rostral lumbar segments. These observations continue the characterization of inter-enlargement (long propriospinal) pathways, illustrating a substantial and largely reciprocal inter-enlargement network with large numbers of both ascending and descending ventrolateral commissural neurons. These pathways are anatomically well-suited to the task of interlimb coordination and to participate in the remarkable recovery of locomotor function seen in the rat following thoracic spinal cord injuries that spare as little as 20% of the total white matter cross sectional area. PMID:19766612

  9. Cervical Pre-Phrenic Interneurons in the Normal and Lesioned Spinal Cord of the Adult Rat

    PubMed Central

    Lane, Michael A.; White, Todd E.; Coutts, Marcella A.; Jones, Alex L.; Sandhu, Milapjit S.; Bloom, David C.; Bolser, Donald C.; Yates, Bill J.; Fuller, David D.; Reier, Paul J.

    2008-01-01

    While monosynaptic bulbospinal projections to phrenic motoneurons have been extensively described, little is known about the organization of phrenic premotor neurons in the adult rat spinal cord. As interneurons may play an important role in normal breathing and recovery following spinal cord injury, the present study has used anterograde and transneuronal retrograde tracing to study their distribution and synaptic relations. Exclusive unilateral, first-order labeling of the phrenic motoneuron pool with pseudorabies virus demonstrated a substantial number of second-order, bilaterally-distributed cervical interneurons predominantly in the dorsal horn and around the central canal. Combined transneuronal and anterograde tracing revealed ventral respiratory column projections to pre-phrenic interneurons suggesting some propriospinal relays exist between medullary neurons and the phrenic nucleus. Dual-labeling studies with pseudorabies virus recombinants also showed pre-phrenic interneurons integrated with either contralateral phrenic or intercostal motoneuron pools. The stability of interneuronal pseudorabies virus labeling patterns following lateral cervical hemisection was then addressed. Except for fewer infected contralateral interneurons at the level of the central canal, the number and distribution of phrenic-associated interneurons was not significantly altered two weeks post-hemisection (i.e. when the earliest post-injury recovery of phrenic activity has been reported). These results demonstrate a heterogeneous population of phrenic-related interneurons. Their connectivity and relative stability after cervical hemisection raises speculation for potentially diverse roles in modulating phrenic function normally and post-injury. PMID:18924146

  10. 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

  11. Effects of lesions to the dorsal and ventral hippocampus on defensive behaviors in rats.

    PubMed

    Pentkowski, Nathan S; Blanchard, D Caroline; Lever, Colin; Litvin, Yoav; Blanchard, Robert J

    2006-04-01

    This study investigated the role of the hippocampus in both unconditioned and conditioned defensive behaviors by examining the effects of pretraining ibotenic acid lesions to the dorsal and ventral hippocampus in male Long-Evans hooded rats exposed to three types of threat stimuli: cat-odor, a live cat and footshock. Defensive behaviors were assessed during exposure to cat-odor and a live cat, and immediately following the presentation of footshock. Conditioned defensive behaviors were also assessed in each context 24 h after initial threat exposure. During both unconditioned and conditioned trials, dorsal hippocampal lesions failed to significantly alter any behavioral measure in each test of defense. In contrast, ventral hippocampal lesions significantly reduced unconditioned defensive behaviors during exposure to cat-odor without producing any observable effects during cat exposure. Furthermore, ventral lesions significantly attenuated conditioned defensive behaviors following the administration of footshock and during re-exposure to each context. These results suggest a specific role for the ventral, not dorsal, hippocampus in modulating anxiety-like behaviors in certain animal models of defense. PMID:16630065

  12. Depressing effect of electroacupuncture on the spinal non-painful sensory input of the rat.

    PubMed

    Quiroz-González, Salvador; Segura-Alegría, Bertha; Jiménez-Estrada, Ismael

    2014-09-01

    The aim of this study was to explore the effect of electroacupuncture (EA) applied in the Zusanli (ST36) and Sanyinjiao (SP6) points on the N1 component of the cord dorsum potential (CDP) evoked by electrical stimulation of the sural nerve (SU) in the rat. The experiments were performed in 44 Wistar rats (250-300 g) anesthetized with ketamine (100 mg/kg) and xylazine (2 mg/kg). A bilateral laminectomy was performed to expose the L3 to S2 segments of the spinal cord. The SU nerve was exposed and placed on pairs of hook electrodes for electrical stimulation. The N1-CDPs were recorded with three silver-ball electrodes located on the dorsal surface of the L5 to S1 segments. Ipsilateral high and low EA stimulation (100, 2 Hz, 6 mA, 30 min) induced a considerable reduction in the amplitude (45 ± 5.6, 41 ± 6.2%) of the N1-CDP recorded at the L6 segmental level. Recovery of the N1-CDP amplitude occurred approximately 1-3 s after EA. Sectioning of the saphenous and superficial peroneal nerves reduced the depressing effect provoked by the EA stimulation (18.7 ± 1.3, 27 ± 3.8%). Similarly, sectioning of the posterior and anterior tibial, deep peroneal and gastrocnemius nerves partially reduced the effect provoked by EA (11 ± 1.5, 9.8 ± 1.1, 12.6 ± 1.9%). Intravenous picrotoxin (1 mg/kg) also reduced the action of low and high EA (23 ± 4.8, 27 ± 5.2%). It is suggested that EA stimulation depresses non-painful sensory pathways through the activation of specific inhibitory pathways that receive modulatory actions from other sensory and muscle afferent inputs in the rat spinal cord. PMID:24770863

  13. Bipolar spinal cord stimulation attenuates mechanical hypersensitivity at an intensity that activates a small portion of A-fiber afferents in spinal nerve-injured rats.

    PubMed

    Yang, F; Carteret, A F; Wacnik, P W; Chung, C-Y; Xing, L; Dong, X; Meyer, R A; Raja, S N; Guan, Y

    2011-12-29

    Spinal cord stimulation (SCS) is used clinically to treat neuropathic pain states, but the precise mechanism by which it attenuates neuropathic pain remains to be established. The profile of afferent fiber activation during SCS and how it may correlate with the efficacy of SCS-induced analgesia are unclear. After subjecting rats to an L5 spinal nerve ligation (SNL), we implanted a miniature quadripolar electrode similar to that used clinically. Our goal was to determine the population and number of afferent fibers retrogradely activated by SCS in SNL rats by recording the antidromic compound action potential (AP) at the sciatic nerve after examining the ability of bipolar epidural SCS to alleviate mechanical hypersensitivity in this model. Notably, we compared the profiles of afferent fiber activation to SCS between SNL rats that exhibited good SCS-induced analgesia (responders) and those that did not (nonresponders). Additionally, we examined how different contact configurations affect the motor threshold (MoT) and compound AP threshold. Results showed that three consecutive days of SCS treatment (50 Hz, 0.2 ms, 30 min, 80-90% of MoT), but not sham stimulation, gradually alleviated mechanical hypersensitivity in SNL rats. The MoT obtained in the animal behavioral study was significantly less than the Aα/β-threshold of the compound AP determined during electrophysiological recording, suggesting that SCS could attenuate mechanical hypersensitivity with a stimulus intensity that recruits only a small fraction of the A-fiber population in SNL rats. Although both the MoT and compound AP threshold were similar between responders and nonresponders, the size of the compound AP waveform at higher stimulation intensities was larger in the responders, indicating a more efficient activation of the dorsal column structure in responders. PMID:22001681

  14. Decreased Spinothalamic and Dorsal Column Medial Lemniscus-Mediated Function Is Associated with Neuropathic Pain after Spinal Cord Injury

    PubMed Central

    Cruz-Almeida, Yenisel; Felix, Elizabeth R.; Martinez-Arizala, Alberto

    2012-01-01

    Abstract Neuropathic pain (NP) after spinal cord injury (SCI) can significantly and negatively affect quality of life and is often refractory to currently available treatments. In order to find more effective therapeutic avenues, it would be helpful to identify the primary underlying pathophysiological mechanisms in each individual. The aim of the present study was to assess the relationship between the presence and severity of NP after SCI and measures of somatosensory function mediated via the dorsal column medial lemniscal (DCML) pathway and the spinothalamic tract (STT). Vibratory, mechanical, thermal, and pain thresholds measured in areas at and below the neurological level of injury (LOI) in persons with SCI and NP (SCI-NP, n=47) and in persons with SCI without NP (SCI-noNP, n=18) were normalized to data obtained from able-bodied pain-free control subjects (A-B, n=30). STT-mediated function at and below the LOI was significantly impaired in both SCI groups compared with A-B controls (p<0.001), but not significantly different between the two SCI groups (NP vs. no-NP). In contrast, the SCI-NP group had significantly greater impairment of DCML-mediated function at the LOI, as reflected by greater vibratory detection deficits (z=−3.89±0.5), compared with the SCI-noNP group (z=−1.95±0.7, p=0.034). Within the SCI-NP group, NP severity was significantly associated with increased thermal sensitivity below the LOI (r=0.50, p=0.038). Our results suggest that both impaired STT and DCML-mediated function are necessary for the development of NP after SCI. However, within the SCI-NP group, greater NP severity was associated with greater sensitivity to thermal stimuli below the LOI. This finding concurs with other studies suggesting that STT damage with some sparing is associated with NP. PMID:22845918

  15. Single-prolonged stress induces apoptosis in dorsal raphe nucleus in the rat model of posttraumatic stress disorder

    PubMed Central

    2012-01-01

    Introduction Post-traumatic stress disorder (PTSD) is an anxiety disorder that develops after exposure to a life-threatening traumatic experience. Meta-analyses of the brainstem showed that midsagittal area of the pons was significantly reduced in patients with PTSD, suggesting a potential apoptosis in dorsal raphe nucleus after single-prolonged stress (SPS). The aim of this study is to investigate whether SPS induces apoptosis in dorsal raphe nucleus in PTSD rats, which may be a possible mechanism of reduced volume of pons and density of gray matter. Methods In this study, rats were randomly divided into 1d, 7d and 14d groups after SPS along with the control group. The apoptosis rate was determined using annexin V-FITC/PI double-labeled flow cytometry (FCM). Levels of Cytochrome c (Cyt-C) was examined by Western blotting. Expression of Cyt-C on mitochondria in the dorsal raphe nucleus neuron was determined by enzymohistochemistry under transmission electron microscopy (TEM). The change of thiamine monophosphatase (TMP) levels was assessed by enzymohistochemistry under light microscope and TEM. Morphological changes of the ultrastructure of the dorsal raphe nucleus neuron were determined by TEM. Results Apoptotic morphological alterations were observed in dorsal raphe nucleus neuron for all SPS-stimulate groups of rats. The apoptosis rates were significantly increased in dorsal raphe nucleus neuron of SPS rats, along with increased release of cytochrome c from the mitochondria into the cytoplasm, increased expression of Cyt-C and TMP levels in the cytoplasm, which reached to the peak of increase 7 days of SPS. Conclusions The results indicate that SPS induced Cyt-C released from mitochondria into cytosol and apoptosis in dorsal raphe nucleus neuron of rats. Increased TMP in cytoplasm facilitated the clearance of apoptotic cells. We propose that this presents one of the mechanisms that lead to reduced volume of pons and gray matter associated with PTSD. PMID

  16. Intact sciatic myelinated primary afferent terminals collaterally sprout in the adult rat dorsal horn following section of a neighbouring peripheral nerve.

    PubMed

    Doubell, T P; Mannion, R J; Woolf, C J

    1997-03-31

    Peripheral nerve section induces sprouting of the central terminals of axotomized myelinated primary afferents outside their normal dorsoventral termination zones in lamina I, III, and IV of the dorsal horn into lamina II, an area that normally only receives unmyelinated C-fiber input. This axotomy-induced regenerative sprouting is confined to the somatotopic boundaries of the injured nerve in the spinal cord. We examined whether intact myelinated sciatic afferents are able to sprout novel terminals into neighbouring areas of the dorsal horn in the adult rat following axotomy of two test nerves, either the posterior cutaneous nerve of the thigh or the saphenous nerve. These peripheral nerves have somatotopically organized terminal areas in the dorsal horn that overlap in some areas and are contiguous in others, with that of the sciatic central terminal field. Two weeks after cutting either the posterior cutaneous or the saphenous nerve, intact sciatic myelinated fibers labelled with the B fragment of cholera toxin conjugated to horseradish peroxidase (B-HRP) sprouted into an area of lamina II normally only innervated by the adjacent injured test nerve. This collateral sprouting was strictly limited, however, to those particular areas of the dorsal horn where the A-fiber terminal field of the control sciatic and the C-fiber terminal field of the injured test nerve overlapped in the dorsoventral plane. No mediolateral sprouting was seen into those areas of neuropil solely innervated by the test nerve. We conclude that intact myelinated primary afferents do have the capacity to collaterally sprout, but that any resultant somatotopic reorganization of central projections is limited to the dorsoventral plane. These changes may contribute to sensory hypersensitivity at the edges of denervated skin. PMID:9073085

  17. Gastric dysreflexia after acute experimental spinal cord injury in rats

    PubMed Central

    Tong, M.; Holmes, G. M.

    2009-01-01

    Gastric reflexes are mediated mainly by vago-vagal reflex circuits in the caudal medulla. Despite the fact that brainstem vago-vagal circuitry remains intact after spinal cord injury (SCI), patients with SCI at the cervical level most often present gastric stasis with an increased risk of reflux and aspiration of gastric contents. Using a miniature strain gauge sutured to the gastric surface; we tested gastric motility and reflexive gastric relaxation following oesophageal distension (oesophageal-gastric relaxation reflex) in animals 3 days after a severe spinal contusion at either the third or ninth thoracic spinal segment (acute T3- or T9 SCI, respectively). Both basal gastric motility and the oesophageal-gastric relaxation reflex were significantly diminished in animals with T3 SCI. Conversely, both basal gastric motility and the oesophageal-gastric relaxation reflex were not significantly reduced in T9 SCI animals compared to controls. The reduced gastric motility and oesophageal-gastric reflex in T3 SCI rats was not ameliorated by celiac sympathectomy. Our results show that gastric stasis following acute SCI is independent of altered spinal sympathetic input to the stomach caudal to the lesion. Our data suggest that SCI may alter the sensitivity of vagal reflex function, perhaps by interrupting ascending spinosolitary input to brainstem vagal nuclei. PMID:19126185

  18. Modification of radiation damage in rat spinal cord by mitotane

    SciTech Connect

    Glicksman, A.S.; Bliven, S.F.; Leith, J.T.

    1982-07-01

    Modification of the paralytic response in rats after 6-MV photon irradiation of the spinal cord with either single or split exposures (two equal fractions given in a 24-hour period) by mitotane was investigated. Mitotane was administered as a suspension in physiologic saline (300 mg/kg/day) for either 5 days prior to or 5 days after irradiation. For rats receiving split doses of 6-MV photons, either the last two doses of mitotane were given 2 hours prior to each radiation fraction or mitotane was begun 2 hours after the second fraction and continued for 5 days. The data to 6 months after irradiation indicate that, in rats given mitotane for 5 days prior to single-dose photon irradiation, the paralytic response (as defined by the dose needed to produce paralysis in 50% of the irradiated groups of rats) was enhanced by a dose-enhancement factor (DEF) of 1.40. The DEF in the group of rats given mitotane after single doses of 6-MV photons was 1.15. In the split-dose irradiation experiments, the DEF for the groups of rats given mitotane prior to each radiation fraction was 1.36; while the DEF for the group of rats receiving mitotane beginning after the second fraction was 1.18. These data indicate that mitotane can potentiate the effects of 6-MV photon irradiation to the central nervous system, with mitotane administered prior to irradiation being the most effective sequence.

  19. Prokineticin 2 potentiates acid-sensing ion channel activity in rat dorsal root ganglion neurons

    PubMed Central

    2012-01-01

    Background Prokineticin 2 (PK2) is a secreted protein and causes potent hyperalgesia in vivo, and is therefore considered to be a new pronociceptive mediator. However, the molecular targets responsible for the pronociceptive effects of PK2 are still poorly understood. Here, we have found that PK2 potentiates the activity of acid-sensing ion channels in the primary sensory neurons. Methods In the present study, experiments were performed on neurons freshly isolated from rat dorsal root ganglion by using whole-cell patch clamp and voltage-clamp recording techniques. Results PK2 dose-dependently enhanced proton-gated currents with an EC50 of 0.22 ± 0.06 nM. PK2 shifted the proton concentration-response curve upwards, with a 1.81 ± 0.11 fold increase of the maximal current response. PK2 enhancing effect on proton-gated currents was completely blocked by PK2 receptor antagonist. The potentiation was also abolished by intracellular dialysis of GF109203X, a protein kinase C inhibitor, or FSC-231, a protein interacting with C-kinase 1 inhibitor. Moreover, PK2 enhanced the acid-evoked membrane excitability of rat dorsal root ganglion neurons and caused a significant increase in the amplitude of the depolarization and the number of spikes induced by acid stimuli. Finally, PK2 exacerbated nociceptive responses to the injection of acetic acid in rats. Conclusion These results suggest that PK2 increases the activity of acid-sensing ion channels via the PK2 receptor and protein kinase C-dependent signal pathways in rat primary sensory neurons. Our findings support that PK2 is a proalgesic factor and its signaling likely contributes to acidosis-evoked pain by sensitizing acid-sensing ion channels. PMID:22642848

  20. Thalamic neuronal activity in rats with mechanical allodynia following contusive spinal cord injury.

    PubMed

    Gerke, M B; Duggan, A W; Xu, L; Siddall, P J

    2003-01-01

    Pain and allodynia following spinal cord injury are poorly understood and difficult to treat. Since there is evidence that supraspinal mechanisms are important in such pain, we have studied the role of the thalamus in an experimental model of spinal injury. Extracellular recordings were obtained from neurones of the thalamic nucleus ventralis postero-lateralis (VPL) in normal rats and those which had sustained a contusive spinal cord injury to the thoraco-lumbar junction 7 days previously. Behavioural testing with von Frey hairs established that 11 spinally injured rats showed exaggerated vocal responses to normally innocuous mechanical stimulation (allodynia) whereas eight were non-allodynic. Thalamic VPL neurones in spinally injured rats (both allodynic and non-allodynic) exhibited a dysrhythmia in that a significantly higher proportion fired spontaneously in an oscillatory mode when compared with neurones in uninjured rats. Thus this dysrhythmia was linked to spinal injury, not to allodynia. The evoked responses of VPL thalamic neurones to brushing the skin, however, were significantly elevated in allodynic rats when compared with those in uninjured rats and neuronal afterdischarges to these stimuli (which were absent in uninjured rats) were more common in allodynic than in non-allodynic rats. We have previously reported that a proportion of spinal neurones in allodynic spinally injured rats show increased evoked responses and afterdischarges following brushing the skin and hence the enhanced thalamic responses may reflect a greater spinal input. In view of the increasing evidence that thalamo-cortical rhythmical firing is linked to sensorimotor and cognitive brain functions, we propose that pain following brushing the skin results from an exaggerated spinal input being processed by a dysrhythmic thalamus. Thus both spinal and thalamic mechanisms may be important in the genesis of pain and allodynia following spinal cord injury. PMID:12617975

  1. MAPK Pathways Are Involved in Neuropathic Pain in Rats with Chronic Compression of the Dorsal Root Ganglion

    PubMed Central

    Jia, Lei; Zhang, Xiao; Wei, Hui

    2016-01-01

    The aim of the present study was to investigate whether the MAPK pathways were involved in the mechanism of neuropathic pain in rats with chronic compression of the dorsal root ganglion. We determined the paw withdrawal mechanical threshold (PWMT) of rats before and after CCD surgery and then after p38, JNK, or ERK inhibitors administration. Western blotting, RT-PCR, and immunofluorescence of dorsal root ganglia were performed to investigate the protein and mRNA level of MAPKs and also the alternation in distributions of positive neurons in dorsal root ganglia. Intrathecal administration of MAPKs inhibitors, SB203580 (p38 inhibitor), SP600125 (JNK inhibitor), and U0126 (ERK inhibitor), resulted in a partial reduction in CCD-induced mechanical allodynia. The reduction of allodynia was associated with significant depression in the level of both MAPKs mRNA and protein expression in CCD rats and also associated with the decreased ratios of large size MAPKs positive neurons in dorsal root ganglia. In conclusion, the specific inhibitors of MAPKs contributed to the attenuation of mechanical allodynia in CCD rats and the large size MAPKs positive neurons in dorsal root ganglia were crucial. PMID:27504140

  2. Effects of Electroacupuncture at Governor Vessel Acupoints on Neurotrophin-3 in Rats with Experimental Spinal Cord Injury

    PubMed Central

    Lv, Wei; Song, Liang-yu; Song, Hong-tao; Yuan, Xiao-chen; Mao, Ying-qiu; Jing, Quan-kai

    2016-01-01

    In an effort to explore new, noninvasive treatment options for spinal cord injuries (SCI), this study investigated the effects of electroacupuncture (EA) for SCI rat models. SCI was induced by a modified Allen's weight-drop method. We investigated the response of EA at Dazhui (GV 14) and Mingmen (GV 4) acupoints to understand the effects and mechanisms of EA in neuroprotection and neuronal function recovery after SCI. BBB testing was used to detect motor function of rats' hind limbs among groups, and EA was shown to promote the recovery of SCI rats' motor function. Nissl staining showed a restored neural morphology and an increase in the quantity of neurons after EA. Also, the antiapoptosis role was exposed by TUNEL staining. Western blotting analysis was used to determine the protein expression of neurotrophin-3 (NT-3) in spinal cord tissue. Compared to the sham group, the expression levels of NT-3 were significantly decreased and EA was shown to upregulate the expression of NT-3. The present study suggests that the role of EA in neuroprotection and dorsal neuronal function recovery after SCI in rats, especially EA stimulation at GV 14 and GV 4, can greatly promote neuronal function recovery, which may result from upregulating the expression of NT-3. PMID:27597902

  3. Effects of Electroacupuncture at Governor Vessel Acupoints on Neurotrophin-3 in Rats with Experimental Spinal Cord Injury.

    PubMed

    Mo, Yu-Ping; Yao, Hai-Jiang; Lv, Wei; Song, Liang-Yu; Song, Hong-Tao; Yuan, Xiao-Chen; Mao, Ying-Qiu; Jing, Quan-Kai; Shi, Su-Hua; Li, Zhi-Gang

    2016-01-01

    In an effort to explore new, noninvasive treatment options for spinal cord injuries (SCI), this study investigated the effects of electroacupuncture (EA) for SCI rat models. SCI was induced by a modified Allen's weight-drop method. We investigated the response of EA at Dazhui (GV 14) and Mingmen (GV 4) acupoints to understand the effects and mechanisms of EA in neuroprotection and neuronal function recovery after SCI. BBB testing was used to detect motor function of rats' hind limbs among groups, and EA was shown to promote the recovery of SCI rats' motor function. Nissl staining showed a restored neural morphology and an increase in the quantity of neurons after EA. Also, the antiapoptosis role was exposed by TUNEL staining. Western blotting analysis was used to determine the protein expression of neurotrophin-3 (NT-3) in spinal cord tissue. Compared to the sham group, the expression levels of NT-3 were significantly decreased and EA was shown to upregulate the expression of NT-3. The present study suggests that the role of EA in neuroprotection and dorsal neuronal function recovery after SCI in rats, especially EA stimulation at GV 14 and GV 4, can greatly promote neuronal function recovery, which may result from upregulating the expression of NT-3. PMID:27597902

  4. The Role of C Fibers in Spinal Microglia Induction and Possible Relation with TRPV3 Expression During Chronic Inflammatory Arthritis in Rats

    PubMed Central

    Gazerani, Sasan; Zaringhalam, Jalal; Manaheji, Homa; Golabi, Sahar

    2016-01-01

    Introduction: Stimulation of peptidergic fibers activates microglia in the dorsal horn. Microglia activation causes fractalkine (FKN) release, a neuron-glia signal, which enhances pain. The transient vanilloid receptor 1 (TRPV1) mediates the release of neuropeptides, which can subsequently activate glia. TRPV1 and TRPV2 are generally expressed on C and Aδ fibers, respectively. Expression of both proteins is upregulated during inflammation, but expression of TRPV3 after induction of inflammation is unclear. Methods: Adult male Wistar rats were used in all experiments. Arthritis was induced in them by single subcutaneous injection of complete Freund’s adjuvant (CFA) in their right hindpaws. Resiniferatoxin (RTX) was used to eliminate peptidergic fibers. We examined the relation between FKN and TRPV3 expression by administration of anti-FKN antibody. Results: Our study findings indicated that 1) spinal TRPV3 was mostly expressed on nonpeptidergic fibers, 2) expression of spinal TRPV3 increased following inflammation, 3) elimination of peptidergic fibers decreased spinal TRPV3 expression, 4) alteration of hyperalgesia was compatible with TRPV3 changes in RTX-treated rat, and 5) anti-FKN antibody reduced spinal TRPV3 expression. Discussion: It seems that the hyperalgesia variation during different phases of CFA-induced arthritis correlates with spinal TRPV3 expression variation on peptidergic fibers. Moreover, spinal microglial activation during CFA inflammation is involved in TRPV3 expression changes via FKN signaling. PMID:27563416

  5. Generation patterns of four groups of cholinergic neurons in rat cervical spinal cord: a combined tritiated thymidine autoradiographic and choline acetyltransferase immunocytochemical study

    SciTech Connect

    Phelps, P.E.; Barber, R.P.; Vaughn, J.E.

    1988-07-22

    This report examines the generation of cholinergic neurons in the spinal cord in order to determine whether the transmitter phenotype of neurons is associated with specific patterns of neurogenesis. Previous immunocytochemical studies identified four groups of choline acetyltransferase (ChAT)-positive neurons in the cervical enlargement of the rat spinal cord. These cell groups vary in both somatic size and location along the previously described ventrodorsal neurogenic gradient of the spinal cord. Thus, large (and small) motoneurons are located in the ventral horn, medium-sized partition cells are found in the intermediate gray matter, small central canal cluster cells are situated within lamina X, and small dorsal horn neurons are scattered predominantly through laminae III-V. The relationships among the birthdays of these four subsets of cholinergic neurons have been examined by combining 3H-thymidine autoradiography and ChAT immunocytochemistry. Embryonic day 11 was the earliest time that neurons were generated within the cervical enlargement. Large and small ChAT-positive motoneurons were produced on E11 and 12, with 70% of both groups being born on E11. ChAT-positive partition cells were produced between E11 and 13, with their peak generation occurring on E12. Approximately 70% of the cholinergic central canal cluster and dorsal horn cells were born on E13, and the remainder of each of these groups was generated on E14. Other investigators have shown that all neurons within the rat cervical spinal cord are produced in a ventrodorsal sequence between E11 and E16. In contrast, ChAT-positive neurons are born only from E11 to E14 and are among the earliest cells generated in the ventral, intermediate, and dorsal subdivisions of the spinal cord.

  6. Social interaction with a cagemate in pain facilitates subsequent spinal nociception via activation of the medial prefrontal cortex in rats.

    PubMed

    Li, Zhen; Lu, Yun-Fei; Li, Chun-Li; Wang, Yan; Sun, Wei; He, Ting; Chen, Xue-Feng; Wang, Xiao-Liang; Chen, Jun

    2014-07-01

    Empathy for the pain experience of others can lead to the activation of pain-related brain areas and can even induce aberrant responses to pain in human observers. Recent evidence shows this high-level emotional and cognitive process also exists in lower animals; however, the mechanisms underlying this phenomenon remain unknown. In the present study we found that, after social interaction with a rat that had received subcutaneous injection of bee venom (BV), only the cagemate observer (CO) but not the noncagemate observer (NCO) showed bilateral mechanical hypersensitivity and an enhanced paw flinch reflex following BV injection. Moreover, neuronal activities labeled by c-Fos immunoreactivity in the spinal dorsal horn of CO rats were also significantly increased relative to the control 1 hour after BV injection. A stress-related response can be excluded because serum corticosterone concentration following social interaction with demonstrator rats in pain was not changed in CO rats relative to NCO and isolated control rats. Anxiety can also be excluded because anxiety-like behaviors could be seen in both the CO and NCO rats tested in the open-field test. Finally, bilateral lesions of the medial prefrontal cortex eliminated the enhancement of the BV-induced paw flinch reflex in CO rats, but bilateral lesions of either the amygdala or the entorhinal cortex failed. Together, we have provided another line of evidence for the existence of familiarity-dependent empathy for pain in rats and have demonstrated that the medial prefrontal cortex plays a critical role in processing the empathy-related enhancement of spinal nociception. PMID:24699208

  7. Spinal cord injury repair by implantation of structured hyaluronic acid scaffold with PLGA microspheres in the rat.

    PubMed

    Wen, Yujun; Yu, Shukui; Wu, Yanhong; Ju, Rongkai; Wang, Hao; Liu, Yujun; Wang, Ying; Xu, Qunyuan

    2016-04-01

    In order to create an optimal microenvironment for neural regeneration in the lesion area after spinal cord injury (SCI), we fabricated a novel scaffold composed of a hyaluronic acid (HA) hydrogel with a longitudinal multi-tubular conformation. The scaffold was modified by binding with an anti-Nogo receptor antibody (antiNgR) and mixed further with poly(lactic-co-glycolic acid) (PLGA) microspheres containing brain-derived neurotrophic factor and vascular endothelial growth factor (HA+PLGA). In the rat, after implantation of this composite into an injured area created by a dorsal hemisection at T9-10 of the spinal cord, favorable effects were seen with regard to the promotion of spinal repair, including excellent integration of the implants with host tissue, inhibition of inflammation, and gliosis. In particular, large numbers of new blood vessels and regenerated nerve fibers were found within and around the implants. Simultaneously, the implanted rats exhibited improved locomotor recovery. Thus, this novel composite material might provide a suitable microenvironment for neural regeneration following SCI. PMID:26463048

  8. Morphine paradoxically prolongs neuropathic pain in rats by amplifying spinal NLRP3 inflammasome activation.

    PubMed

    Grace, Peter M; Strand, Keith A; Galer, Erika L; Urban, Daniel J; Wang, Xiaohui; Baratta, Michael V; Fabisiak, Timothy J; Anderson, Nathan D; Cheng, Kejun; Greene, Lisa I; Berkelhammer, Debra; Zhang, Yingning; Ellis, Amanda L; Yin, Hang Hubert; Campeau, Serge; Rice, Kenner C; Roth, Bryan L; Maier, Steven F; Watkins, Linda R

    2016-06-14

    Opioid use for pain management has dramatically increased, with little assessment of potential pathophysiological consequences for the primary pain condition. Here, a short course of morphine, starting 10 d after injury in male rats, paradoxically and remarkably doubled the duration of chronic constriction injury (CCI)-allodynia, months after morphine ceased. No such effect of opioids on neuropathic pain has previously been reported. Using pharmacologic and genetic approaches, we discovered that the initiation and maintenance of this multimonth prolongation of neuropathic pain was mediated by a previously unidentified mechanism for spinal cord and pain-namely, morphine-induced spinal NOD-like receptor protein 3 (NLRP3) inflammasomes and associated release of interleukin-1β (IL-1β). As spinal dorsal horn microglia expressed this signaling platform, these cells were selectively inhibited in vivo after transfection with a novel Designer Receptor Exclusively Activated by Designer Drugs (DREADD). Multiday treatment with the DREADD-specific ligand clozapine-N-oxide prevented and enduringly reversed morphine-induced persistent sensitization for weeks to months after cessation of clozapine-N-oxide. These data demonstrate both the critical importance of microglia and that maintenance of chronic pain created by early exposure to opioids can be disrupted, resetting pain to normal. These data also provide strong support for the recent "two-hit hypothesis" of microglial priming, leading to exaggerated reactivity after the second challenge, documented here in the context of nerve injury followed by morphine. This study predicts that prolonged pain is an unrealized and clinically concerning consequence of the abundant use of opioids in chronic pain. PMID:27247388

  9. Localization of the endocannabinoid-degrading enzyme fatty acid amide hydrolase in rat dorsal root ganglion cells and its regulation after peripheral nerve injury.

    PubMed

    Lever, Isobel J; Robinson, Michelle; Cibelli, Mario; Paule, Cleoper; Santha, Peter; Yee, Louis; Hunt, Stephen P; Cravatt, Benjamin F; Elphick, Maurice R; Nagy, Istvan; Rice, Andrew S C

    2009-03-25

    Fatty acid amide hydrolase (FAAH) is a degradative enzyme for a group of endogenous signaling lipids that includes anandamide (AEA). AEA acts as an endocannabinoid and an endovanilloid by activating cannabinoid and vanilloid type 1 transient receptor potential (TRPV1) receptors, respectively, on dorsal root ganglion (DRG) sensory neurons. Inhibition of FAAH activity increases AEA concentrations in nervous tissue and reduces sensory hypersensitivity in animal pain models. Using immunohistochemistry, Western blotting, and reverse transcription-PCR, we demonstrate the location of the FAAH in adult rat DRG, sciatic nerve, and spinal cord. In naive rats, FAAH immunoreactivity localized to the soma of 32.7 +/- 0.8% of neurons in L4 and L5 DRG. These were small-sized (mean soma area, 395.96 +/- 5.6 mum(2)) and predominantly colabeled with peripherin and isolectin B4 markers of unmyelinated C-fiber neurons; 68% colabeled with antibodies to TRPV1 (marker of nociceptive DRG neurons), and <2% colabeled with NF200 (marker of large myelinated neurons). FAAH-IR was also present in small, NF200-negative cultured rat DRG neurons. Incubation of these cultures with the FAAH inhibitor URB597 increased AEA-evoked cobalt uptake in a capsazepine-sensitive manner. After sciatic nerve axotomy, there was a rightward shift in the cell-size distribution of FAAH-immunoreactive (IR) DRG neurons ipsilateral to injury: FAAH immunoreactivity was detected in larger-sized cells that colabeled with NF200. An ipsilateral versus contralateral increase in both the size and proportion of FAAH-IR DRG occurred after spinal nerve transection injury but not after chronic inflammation of the rat hindpaw 2 d after injection of complete Freund's adjuvant. This study reveals the location of FAAH in neural tissue involved in peripheral nociceptive transmission. PMID:19321773

  10. Neural correlates for angular head velocity in the rat dorsal tegmental nucleus

    NASA Technical Reports Server (NTRS)

    Bassett, J. P.; Taube, J. S.; Oman, C. M. (Principal Investigator)

    2001-01-01

    Many neurons in the rat lateral mammillary nuclei (LMN) fire selectively in relation to the animal's head direction (HD) in the horizontal plane independent of the rat's location or behavior. One hypothesis of how this representation is generated and updated is via subcortical projections from the dorsal tegmental nucleus (DTN). Here we report the type of activity in DTN neurons. The majority of cells (75%) fired as a function of the rat's angular head velocity (AHV). Cells exhibited one of two types of firing patterns: (1) symmetric, in which the firing rate was positively correlated with AHV during head turns in both directions, and (2) asymmetric, in which the firing rate was positively correlated with head turns in one direction and correlated either negatively or not at all in the opposite direction. In addition to modulation by AHV, some of the AHV cells (40.1%) were weakly modulated by the rat's linear velocity, and a smaller number were modulated by HD (11%) or head pitch (15.9%). Autocorrelation analyses indicated that with the head stationary, AHV cells displayed irregular discharge patterns. Because afferents from the DTN are the major source of information projecting to the LMN, these results suggest that AHV information from the DTN plays a significant role in generating the HD signal in LMN. A model is proposed showing how DTN AHV cells can generate and update the LMN HD cell signal.

  11. Role of Medio-Dorsal Frontal and Posterior Parietal Neurons during Auditory Detection Performance in Rats

    PubMed Central

    Bohon, Kaitlin S.; Wiest, Michael C.

    2014-01-01

    To further characterize the role of frontal and parietal cortices in rat cognition, we recorded action potentials simultaneously from multiple sites in the medio-dorsal frontal cortex and posterior parietal cortex of rats while they performed a two-choice auditory detection task. We quantified neural correlates of task performance, including response movements, perception of a target tone, and the differentiation between stimuli with distinct features (different pitches or durations). A minority of units—15% in frontal cortex, 23% in parietal cortex—significantly distinguished hit trials (successful detections, response movement to the right) from correct rejection trials (correct leftward response to the absence of the target tone). Estimating the contribution of movement-related activity to these responses suggested that more than half of these units were likely signaling correct perception of the auditory target, rather than merely movement direction. In addition, we found a smaller and mostly not overlapping population of units that differentiated stimuli based on task-irrelevant details. The detection-related spiking responses we observed suggest that correlates of perception in the rat are sparsely represented among neurons in the rat's frontal-parietal network, without being concentrated preferentially in frontal or parietal areas. PMID:25479194

  12. Neural correlates for angular head velocity in the rat dorsal tegmental nucleus.

    PubMed

    Bassett, J P; Taube, J S

    2001-08-01

    Many neurons in the rat lateral mammillary nuclei (LMN) fire selectively in relation to the animal's head direction (HD) in the horizontal plane independent of the rat's location or behavior. One hypothesis of how this representation is generated and updated is via subcortical projections from the dorsal tegmental nucleus (DTN). Here we report the type of activity in DTN neurons. The majority of cells (75%) fired as a function of the rat's angular head velocity (AHV). Cells exhibited one of two types of firing patterns: (1) symmetric, in which the firing rate was positively correlated with AHV during head turns in both directions, and (2) asymmetric, in which the firing rate was positively correlated with head turns in one direction and correlated either negatively or not at all in the opposite direction. In addition to modulation by AHV, some of the AHV cells (40.1%) were weakly modulated by the rat's linear velocity, and a smaller number were modulated by HD (11%) or head pitch (15.9%). Autocorrelation analyses indicated that with the head stationary, AHV cells displayed irregular discharge patterns. Because afferents from the DTN are the major source of information projecting to the LMN, these results suggest that AHV information from the DTN plays a significant role in generating the HD signal in LMN. A model is proposed showing how DTN AHV cells can generate and update the LMN HD cell signal. PMID:11466446

  13. Increased vitamin D receptor expression in dorsal root ganglia neurons of diabetic rats.

    PubMed

    Filipović, Natalija; Ferhatović, Lejla; Marelja, Ivana; Puljak, Livia; Grković, Ivica

    2013-08-01

    The effects of vitamin D on the nervous system have been studied extensively. In spite of accumulating data about the substantial changes in the vitamin D receptor (VDR) signaling system, during different types of neuroinflammatory diseases, its role in diabetic neuropathy has not been investigated in detail. To assess the role of VDR signaling in diabetic neuropathy, we examined expression of VDRs in dorsal root ganglia (DRG) neurons in a rat model of streptozotocin-induced diabetes mellitus type 1. Diabetes mellitus (DM) type 1 was induced with streptozotocin in male Sprague-Dawley rats. After two months, expression of VDRs was analyzed immunohistochemically in the cytoplasm of L4 and L5 DRG neurons of diabetic rats. Semi-quantitative analysis for the determination of staining in nuclei and plasma-membranes of DRG neurons was performed. A significant increase in VDR expression was observed in DRG neurons of diabetic rats. Expression of VDRs was increased in the cytoplasm, nuclei and in cell membranes of neurons. An increase in VDR expression occurred in all neurons, but the greatest increase of fluorescence intensity in cytoplasm was observed in neurons of small diameter. Results of the present study indicate that the VDR signaling system could be a potential therapeutic target for diabetic neuropathy. PMID:23684983

  14. Spinal neuronal activation during locomotor-like activity enabled by epidural stimulation and 5-HT agonists in spinal rats

    PubMed Central

    Duru, Paul O.; Tillakaratne, Niranjala J.K.; Kim, Jung A.; Zhong, Hui; Stauber, Stacey M.; Pham, Trinh T.; Xiao, Mei S.; Edgerton, V. Reggie; Roy, Roland R.

    2015-01-01

    The neural networks that generate stepping in complete spinal adult rats remain poorly defined. To address this problem we used c-fos (an activity-dependent marker) to identify active interneurons and motoneurons in the lumbar spinal cord of adult spinal rats during a 30-minute bout of bipedal stepping. Spinal rats were either step trained (30 min/day, 3 days/week for 7.5 weeks) or not step-trained. Stepping was enabled by epidural stimulation and the administration of the serotonergic agonists quipazine and 8-OHDPAT. A third group of spinal rats served as untreated (no stimulation, drugs, or stepping) controls. The number of activated cholinergic central canal cluster cells and partition neurons was higher in both step-trained and non-trained than untreated rats, and higher in non-trained than step-trained rats. The latter finding suggests that daily treatment with epidural stimulation plus serotonergic agonist treatment without step training enhanced the excitability of a broader cholinergic interneuronal population than step training. The number of activated interneurons in laminae II-VI of lumbar cross sections was higher in both step-trained and non-trained than untreated rats, and highest in step-trained rats. This finding suggests that this population of interneurons was responsive to epidural stimulation plus serotonergic treatment and that load-bearing induced when stepping had an additive effect. The number of activated motoneurons of all size categories was higher in the step-trained than the other two groups, reflecting a strong effect of loading on motoneuron recruitment. In general, these results indicate that the spinal networks for locomotion are similar with and without brain input. PMID:25789848

  15. Nanomolar Oxytocin Synergizes with Weak Electrical Afferent Stimulation to Activate the Locomotor CPG of the Rat Spinal Cord In Vitro

    PubMed Central

    Dose, Francesco; Zanon, Patrizia; Coslovich, Tamara; Taccola, Giuliano

    2014-01-01

    Synergizing the effect of afferent fibre stimulation with pharmacological interventions is a desirable goal to trigger spinal locomotor activity, especially after injury. Thus, to better understand the mechanisms to optimize this process, we studied the role of the neuropeptide oxytocin (previously shown to stimulate locomotor networks) on network and motoneuron properties using the isolated neonatal rat spinal cord. On motoneurons oxytocin (1 nM–1 μM) generated sporadic bursts with superimposed firing and dose-dependent depolarization. No desensitization was observed despite repeated applications. Tetrodotoxin completely blocked the effects of oxytocin, demonstrating the network origin of the responses. Recording motoneuron pool activity from lumbar ventral roots showed oxytocin mediated depolarization with synchronous bursts, and depression of reflex responses in a stimulus and peptide-concentration dependent fashion. Disinhibited bursting caused by strychnine and bicuculline was accelerated by oxytocin whose action was blocked by the oxytocin antagonist atosiban. Fictive locomotion appeared when subthreshold concentrations of NMDA plus 5HT were coapplied with oxytocin, an effect prevented after 24 h incubation with the inhibitor of 5HT synthesis, PCPA. When fictive locomotion was fully manifested, oxytocin did not change periodicity, although cycle amplitude became smaller. A novel protocol of electrical stimulation based on noisy waveforms and applied to one dorsal root evoked stereotypic fictive locomotion. Whenever the stimulus intensity was subthreshold, low doses of oxytocin triggered fictive locomotion although oxytocin per se did not affect primary afferent depolarization evoked by dorsal root pulses. Among the several functional targets for the action of oxytocin at lumbar spinal cord level, the present results highlight how small concentrations of this peptide could bring spinal networks to threshold for fictive locomotion in combination with other

  16. Expression of the vesicular glutamate transporters-1 and -2 in adult mouse dorsal root ganglia and spinal cord and their regulation by nerve injury.

    PubMed

    Brumovsky, P; Watanabe, M; Hökfelt, T

    2007-06-29

    The expression of two vesicular glutamate transporters (VGLUTs), VGLUT1 and VGLUT2, was studied with immunohistochemistry in lumbar dorsal root ganglia (DRGs), the lumbar spinal cord and the skin of the adult mouse. About 12% and 65% of the total number of DRG neuron profiles (NPs) expressed VGLUT1 and VGLUT2, respectively. VGLUT1-immunoreactive (IR) NPs were usually medium- to large-sized, in contrast to a majority of small- or medium-sized VGLUT2-IR NPs. Most VGLUT1-IR NPs did not coexpress calcitonin gene-related peptide (CGRP) or bound isolectin B4 (IB4). In contrast, approximately 31% and approximately 42% of the VGLUT2-IR DRG NPs were also CGRP-IR or bound IB4, respectively. Conversely, virtually all CGRP-IR and IB4-binding NPs coexpressed VGLUT2. Moderate colocalization between VGLUT1 and VGLUT2 was also observed. Sciatic nerve transection induced a decrease in the overall number of VGLUT1- and VGLUT2-IR NPs (both ipsi- and contralaterally) and, in addition, a parallel, unilateral increase of VGLUT2-like immunoreactivity (LI) in a subpopulation of mostly small NPs. In the dorsal horn of the spinal cord, strong VGLUT1-LI was detected, particularly in deep dorsal horn layers and in the ventral horns. VGLUT2-LI was abundant throughout the gray spinal matter, 'radiating' into/from the white matter. A unilateral dorsal rhizotomy reduced VGLUT1-LI, while apparently leaving unaffected the VGLUT2-LI. Transport through axons for both VGLUTs was confirmed by their accumulation after compression of the sciatic nerve or dorsal roots. In the hind paw skin, abundant VGLUT2-IR nerve fibers were observed, sometimes associated with Merkel cells. Lower numbers of VGLUT1-IR fibers were also detected in the skin. Some VGLUT1-IR and VGLUT2-IR fibers were associated with hair follicles. Based on these data and those by Morris et al. [Morris JL, Konig P, Shimizu T, Jobling P, Gibbins IL (2005) Most peptide-containing sensory neurons lack proteins for exocytotic release and

  17. Connectivity of Pacemaker Neurons in the Neonatal Rat Superficial Dorsal Horn

    PubMed Central

    Ford, Neil C.; Arbabi, Shahriar; Baccei, Mark L.

    2014-01-01

    Pacemaker neurons with an intrinsic ability to generate rhythmic burst-firing have been characterized in lamina I of the neonatal spinal cord, where they are innervated by high-threshold sensory afferents. However, little is known about the output of these pacemakers, as the neuronal populations which are targeted by pacemaker axons have yet to be identified. The present study combines patch clamp recordings in the intact neonatal rat spinal cord with tract-tracing to demonstrate that lamina I pacemaker neurons contact multiple spinal motor pathways during early life. Retrograde labeling of premotor interneurons with the trans-synaptic virus PRV-152 revealed the presence of burst-firing in PRV-infected lamina I neurons, thereby confirming that pacemakers are synaptically coupled to motor networks in the spinal ventral horn. Notably, two classes of pacemakers could be distinguished in lamina I based on cell size and the pattern of their axonal projections. While small pacemaker neurons possessed ramified axons which contacted ipsilateral motor circuits, large pacemaker neurons had unbranched axons which crossed the midline and ascended rostrally in the contralateral white matter. Recordings from identified spino-parabrachial and spino-PAG neurons indicated the presence of pacemaker activity within neonatal lamina I projection neurons. Overall, these results show that lamina I pacemakers are positioned to regulate both the level of activity in developing motor circuits as well as the ascending flow of nociceptive information to the brain, thus highlighting a potential role for pacemaker activity in the maturation of pain and sensorimotor networks in the CNS. PMID:25380417

  18. Differential Activation of TRP Channels in the Adult Rat Spinal Substantia Gelatinosa by Stereoisomers of Plant-Derived Chemicals.

    PubMed

    Kumamoto, Eiichi; Fujita, Tsugumi

    2016-01-01

    Activation of TRPV1, TRPA1 or TRPM8 channel expressed in the central terminal of dorsal root ganglion (DRG) neuron increases the spontaneous release of l-glutamate onto spinal dorsal horn lamina II (substantia gelatinosa; SG) neurons which play a pivotal role in regulating nociceptive transmission. The TRP channels are activated by various plant-derived chemicals. Although stereoisomers activate or modulate ion channels in a distinct manner, this phenomenon is not fully addressed for TRP channels. By applying the whole-cell patch-clamp technique to SG neurons of adult rat spinal cord slices, we found out that all of plant-derived chemicals, carvacrol, thymol, carvone and cineole, increase the frequency of spontaneous excitatory postsynaptic current, a measure of the spontaneous release of l-glutamate from nerve terminals, by activating TRP channels. The presynaptic activities were different between stereoisomers (carvacrol and thymol; (-)-carvone and (+)-carvone; 1,8-cineole and 1,4-cineole) in the extent or the types of TRP channels activated, indicating that TRP channels in the SG are activated by stereoisomers in a distinct manner. This result could serve to know the properties of the central terminal TRP channels that are targets of drugs for alleviating pain. PMID:27483289

  19. Axotomy of tributaries of the pelvic and pudendal nerves induces changes in the neurochemistry of mouse dorsal root ganglion neurons and the spinal cord.

    PubMed

    McCarthy, Carly J; Tomasella, Eugenia; Malet, Mariana; Seroogy, Kim B; Hökfelt, Tomas; Villar, Marcelo J; Gebhart, G F; Brumovsky, Pablo R

    2016-05-01

    Using immunohistochemical techniques, we characterized changes in the expression of several neurochemical markers in lumbar 4-sacral 2 (L4-S2) dorsal root ganglion (DRG) neuron profiles (NPs) and the spinal cord of BALB/c mice after axotomy of the L6 and S1 spinal nerves, major tributaries of the pelvic (targeting pelvic visceral organs) and pudendal (targeting perineum and genitalia) nerves. Sham animals were included. Expression of cyclic AMP-dependent transcription factor 3 (ATF3), calcitonin gene-related peptide (CGRP), transient receptor potential cation channel subfamily V, member 1 (TRPV1), tyrosine hydroxylase (TH) and vesicular glutamate transporters (VGLUT) types 1 and -2 was analysed seven days after injury. L6-S1 axotomy induced dramatic de novo expression of ATF3 in many L6-S1 DRG NPs, and parallel significant downregulations in the percentage of CGRP-, TRPV1-, TH- and VGLUT2-immunoreactive (IR) DRG NPs, as compared to their expression in uninjured DRGs (contralateral L6-S1-AXO; sham mice); VGLUT1 expression remained unaltered. Sham L6-S1 DRGs only showed a small ipsilateral increase in ATF3-IR NPs (other markers were unchanged). L6-S1-AXO induced de novo expression of ATF3 in several lumbosacral spinal cord motoneurons and parasympathetic preganglionic neurons; in sham mice the effect was limited to a few motoneurons. Finally, a moderate decrease in CGRP- and TRPV1-like-immunoreactivities was observed in the ipsilateral superficial dorsal horn neuropil. In conclusion, injury of a mixed visceral/non-visceral nerve leads to considerable neurochemical alterations in DRGs matched, to some extent, in the spinal cord. Changes in these and potentially other nociception-related molecules could contribute to pain due to injury of nerves in the abdominopelvic cavity. PMID:25749859

  20. Chronic At- and Below-Level Pain after Moderate Unilateral Cervical Spinal Cord Contusion in Rats

    PubMed Central

    Wade, Rodel E.; Houlé, John D.

    2013-01-01

    Abstract Chronic neuropathic pain is a significant consequence of spinal cord injury (SCI) that is associated with evoked pain, including allodynia and/or hyperalgesia. Allodynia is defined as a painful response to normally innocuous stimuli, and hyperalgesia occurs when there is an amplified pain response to normally noxious stimuli. We describe a model of a unilateral cervical level (C5) contusion injury where sensory recovery was assessed weekly for 6 weeks in 32 adult, female, Sprague-Dawley rats. Bilateral thermal hyperalgesia and tactile allodynia are detectable in the fore- and hindpaws as early as 7 days post-injury (dpi) and persist for at least 42 days. Paw withdrawal latency in response to a noxious thermal stimulus significantly intra-animal pre-operative values. Change in paw withdrawal latency plateaued at 21 dpi. Interestingly, bilateral forepaw allodynia develops in fewer than 40% of rats as measured by von Frey monofilament testing. Similar results occur in the hindpaws, where bilateral allodynia occurs in 46% of rats with SCI. The contralesional forepaw and both hindpaws of rats showed a slight increase in paw withdrawal threshold to tactile stimuli acutely after SCI, corresponding to ipsilesional forelimb motor deficits that resolve over time. That there is no difference among allodynic and non-allodynic groups in overall spared tissue or specifically of the dorsal column or ventrolateral white matter where ascending sensory tracts reside suggests that SCI-induced pain does not depend solely on the size or extent of the lesion, but that other mechanisms are in play. These observations provide a valid model system for future testing of therapeutic interventions to prevent the onset or to reduce the debilitating effects of chronic neuropathic pain after SCI. PMID:23216008

  1. Protein kinases paralleling late-phase LTP formation in dorsal hippocampus in the rat.

    PubMed

    Li, Lin; Wan, Jia; Sase, Sunetra; Gröger, Marion; Pollak, Arnold; Korz, Volker; Lubec, Gert

    2014-10-01

    Hippocampal long term potentiation (LTP), representing a cellular model for learning and memory formation, can be dissociated into at least two phases: a protein-synthesis-independent early phase, lasting about 4h and a protein-synthesis-dependent late phase LTP lasting 6h or longer, or even days. A large series of protein kinases have been shown to be involved and herein, a distinct set of protein kinases proposed to be involved in memory retrieval in previous work was tested in dorsal hippocampus of the rat following induction of late-phase LTP. A bipolar stimulation electrode was chronically implanted into the perforant path, while two monopolar recording electrodes were implanted into the dentate gyrus of the dorsal hippocampus. The recording electrode was measuring extracellular excitatory postsynaptic potentials, while the other one measured population spikes. Protein kinases were determined by immunoblotting and immunoflourescence on hippocampal areas showed the distribution pattern of protein kinases PKN1 and NEK7. Induction of LTP was proven, elevated levels for protein kinases PKN1, RPS6KB1, STK4, CDC42BPB, PRKG, TLK, BMX and decreased levels for NEK7, MAK14 and PLK1 were observed. A remarkable overlap of protein kinases observed in spatial memory processes with those proposed in LTP formation was demonstrated. The findings may be relevant for design of future studies on protein kinases and for the interpretation of previous work. PMID:24911953

  2. Edaravone combined with Schwann cell transplantation may repair spinal cord injury in rats

    PubMed Central

    Zhang, Shu-quan; Wu, Min-fei; Piao, Zhe; Yao, Jin; Li, Ji-hai; Wang, Xin-gang; Liu, Jun

    2015-01-01

    Edaravone has been shown to delay neuronal apoptosis, thereby improving nerve function and the microenvironment after spinal cord injury. Edaravone can provide a favorable environment for the treatment of spinal cord injury using Schwann cell transplantation. This study used rat models of complete spinal cord transection at T9. Six hours later, Schwann cells were transplanted in the head and tail ends of the injury site. Simultaneously, edaravone was injected through the caudal vein. Eight weeks later, the PKH-26-labeled Schwann cells had survived and migrated to the center of the spinal cord injury region in rats after combined treatment with edaravone and Schwann cells. Moreover, the number of PKH-26-labeled Schwann cells in the rat spinal cord was more than that in rats undergoing Schwann cell transplantation alone or rats without any treatment. Horseradish peroxidase retrograde tracing revealed that the number of horseradish peroxidase-positive nerve fibers was greater in rats treated with edaravone combined withSchwann cells than in rats with Schwann cell transplantation alone. The results demonstrated that lower extremity motor function and neurophysiological function were better in rats treated with edaravone and Schwann cells than in rats with Schwann cell transplantation only. These data confirmed that Schwann cell transplantation combined with edaravone injection promoted the regeneration of nerve fibers of rats with spinal cord injury and improved neurological function. PMID:25883621

  3. Electrical high frequency stimulation in the dorsal striatum: Effects on response learning and on GABA levels in rats.

    PubMed

    Schumacher, Anett; de Vasconcelos, Anne Pereira; Lecourtier, Lucas; Moser, Andreas; Cassel, Jean-Christophe

    2011-09-23

    Electrical high frequency stimulation (HFS) has been used to treat various neurological and psychiatric diseases. The striatal area contributes to response learning and procedural memory. Therefore, we investigated the effect of striatal HFS application on procedural/declarative-like memory in rats. All rats were trained in a flooded Double-H maze for three days (4 trials/day) to swim to an escape platform hidden at a constant location. The starting place was the same for all trials. After each training session, HFS of the left dorsal striatum was performed over 4h in alternating 20 min periods (during rest time, 10a.m. to 3p.m.). Nineteen hours after the last HFS and right after a probe trial assessing the rats' strategy (procedural vs. declarative-like memory-based choice), animals were sacrificed and the dorsal striatum was quickly removed. Neurotransmitter levels were measured by HPLC. Stimulated rats did not differ from sham-operated and control rats in acquisition performance, but exhibited altered behavior during the probe trial (procedural memory responses being less frequent than in controls). In stimulated rats, GABA levels were significantly increased in the dorsal striatum on both sides. We suggest that HFS of the dorsal striatum does not alter learning behavior in rats but influences the strategy by which the rats solve the task. Given that the HFS-induced increase of GABA levels was found 19 h after stimulation, it can be assumed that HFS has consequences lasting for several hours and which are functionally significant at a behavioral level, at least under our stimulation (frequency, timing, location, side and strength of stimulation) and testing conditions. PMID:21501632

  4. Music exposure improves spatial cognition by enhancing the BDNF level of dorsal hippocampal subregions in the developing rats.

    PubMed

    Xing, Yingshou; Chen, Wenxi; Wang, Yanran; Jing, Wei; Gao, Shan; Guo, Daqing; Xia, Yang; Yao, Dezhong

    2016-03-01

    Previous research has shown that dorsal hippocampus plays an important role in spatial memory process. Music exposure can enhance brain-derived neurotrophic factor (BDNF) expression level in dorsal hippocampus (DH) and thus enhance spatial cognition ability. But whether music experience may affect different subregions of DH in the same degree remains unclear. Here, we studied the effects of exposure to Mozart K.448 on learning behavior in developing rats using the classical Morris water maze task. The results showed that early music exposure could enhance significantly learning performance of the rats in the water maze test. Meanwhile, the BDNF/TrkB level of dorsal hippocampus CA3 (dCA3) and dentate gyrus (dDG) was significantly enhanced in rats exposed to Mozart music as compared to those without music exposure. In contrast, the BDNF/TrkB level of dorsal hippocampus CA1 (dCA1) was not affected. The results suggest that the spatial memory improvement by music exposure in rats may be associated with the enhanced BDNF/TrkB level of dCA3 and dDG. PMID:26802511

  5. Native store-operated calcium channels are functionally expressed in mouse spinal cord dorsal horn neurons and regulate resting calcium homeostasis

    PubMed Central

    Xia, Jingsheng; Pan, Rong; Gao, Xinghua; Meucci, Olimpia; Hu, Huijuan

    2014-01-01

    Store-operated calcium channels (SOCs) are calcium-selective cation channels that mediate calcium entry in many different cell types. Store-operated calcium entry (SOCE) is involved in various cellular functions. Increasing evidence suggests that impairment of SOCE is responsible for numerous disorders. A previous study demonstrated that YM-58483, a potent SOC inhibitor, strongly attenuates chronic pain by systemic or intrathecal injection and completely blocks the second phase of formalin-induced spontaneous nocifensive behaviour, suggesting a potential role of SOCs in central sensitization. However, the expression of SOCs, their molecular identity and function in spinal cord dorsal horn neurons remain elusive. Here, we demonstrate that SOCs are expressed in dorsal horn neurons. Depletion of calcium stores from the endoplasmic reticulum (ER) induced large sustained calcium entry, which was blocked by SOC inhibitors, but not by voltage-gated calcium channel blockers. Depletion of ER calcium stores activated inward calcium-selective currents, which was reduced by replacing Ca2+ with Ba2+ and reversed by SOC inhibitors. Using the small inhibitory RNA knockdown approach, we identified both STIM1 and STIM2 as important mediators of SOCE and SOC current, and Orai1 as a key component of the Ca2+ release-activated Ca2+ channels in dorsal horn neurons. Knockdown of STIM1, STIM2 or Orai1 decreased resting Ca2+ levels. We also found that activation of neurokinin 1 receptors led to SOCE and activation of SOCs produced an excitatory action in dorsal horn neurons. Our findings reveal that a novel SOC signal is present in dorsal horn neurons and may play an important role in pain transmission. PMID:24860175

  6. Increase of transcription factor EB (TFEB) and lysosomes in rat DRG neurons and their transportation to the central nerve terminal in dorsal horn after nerve injury.

    PubMed

    Jung, J; Uesugi, N; Jeong, N Y; Park, B S; Konishi, H; Kiyama, H

    2016-01-28

    In the spinal dorsal horn (DH), nerve injury activates microglia and induces neuropathic pain. Several studies clarified an involvement of adenosine triphosphate (ATP) in the microglial activation. However, the origin of ATP together with the release mechanism is unclear. Recent in vitro study revealed that an ATP marker, quinacrine, in lysosomes was released from neurite terminal of dorsal root ganglion (DRG) neurons to extracellular space via lysosomal exocytosis. Here, we demonstrate a possibility that the lysosomal ingredient including ATP released from DRG neurons by lysosomal-exocytosis is an additional source of the glial activation in DH after nerve injury. After rat L5 spinal nerve ligation (SNL), mRNA for transcription factor EB (TFEB), a transcription factor controlling lysosomal activation and exocytosis, was induced in the DRG. Simultaneously both lysosomal protein, LAMP1- and vesicular nuclear transporter (VNUT)-positive vesicles were increased in L5 DRG neurons and ipsilateral DH. The quinacrine staining in DH was increased and co-localized with LAMP1 immunoreactivity after nerve injury. In DH, LAMP1-positive vesicles were also co-localized with a peripheral nerve marker, Isolectin B4 (IB4) lectin. Injection of the adenovirus encoding mCherry-LAMP1 into DRG showed that mCherry-positive lysosomes are transported to the central nerve terminal in DH. These findings suggest that activation of lysosome synthesis including ATP packaging in DRG, the central transportation of the lysosome, and subsequent its exocytosis from the central nerve terminal of DRG neurons in response to nerve injury could be a partial mechanism for activation of microglia in DH. This lysosome-mediated microglia activation mechanism may provide another clue to control nociception and pain. PMID:26601776

  7. Time Course of Immediate Early Gene Protein Expression in the Spinal Cord following Conditioning Stimulation of the Sciatic Nerve in Rats

    PubMed Central

    Bojovic, Ognjen; Panja, Debabrata; Bittins, Margarethe; Bramham, Clive R.; Tjølsen, Arne

    2015-01-01

    Long-term potentiation induced by conditioning electrical stimulation of afferent fibers is a widely studied form of synaptic plasticity in the brain and the spinal cord. In the spinal cord dorsal horn, long-term potentiation is induced by a series of high-frequency trains applied to primary afferent fibers. Conditioning stimulation (CS) of sciatic nerve primary afferent fibers also induces expression of immediate early gene proteins in the lumbar spinal cord. However, the time course of immediate early gene expression and the rostral-caudal distribution of expression in the spinal cord have not been systematically studied. Here, we examined the effects of sciatic nerve conditioning stimulation (10 stimulus trains, 0.5 ms stimuli, 7.2 mA, 100 Hz, train duration 2 s, 8 s intervals between trains) on cellular expression of immediate early genes, Arc, c-Fos and Zif268, in anesthetized rats. Immunohistochemical analysis was performed on sagittal sections obtained from Th13- L5 segments of the spinal cord at 1, 2, 3, 6 and 12 h post-CS. Strikingly, all immediate early genes exhibited a monophasic increase in expression with peak increases detected in dorsal horn neurons at 2 hours post-CS. Regional analysis showed peak increases at the location between the L3 and L4 spinal segments. Both Arc, c-Fos and Zif268 remained significantly elevated at 2 hours, followed by a sharp decrease in immediate early gene expression between 2 and 3 hours post-CS. Colocalization analysis performed at 2 hours post-CS showed that all c-Fos and Zif268 neurons were positive for Arc, while 30% and 43% of Arc positive neurons were positive for c-Fos and Zif268, respectively. The present study identifies the spinal cord level and time course of immediate early gene (IEGP) expression of relevance for analysis of IEGPs function in neuronal plasticity and nociception. PMID:25860146

  8. Microglial Activation in Rat Experimental Spinal Cord Injury Model

    PubMed Central

    Abdanipour, Alireza; Tiraihi, Taki; Taheri, Taher; Kazemi, Hadi

    2013-01-01

    Background: The present study was designed to evaluate the secondary microglial activation processes after spinal cord injury (SCI). Methods: A quantitative histological study was performed to determine ED-1 positive cells, glial cell density, and cavitation size in untreated SCI rats at days 1, 2, and 4, and weeks 1, 2, 3, and 4. Results: The results of glial cell quantification along the 4900-µm long injured spinal cord showed a significant increase in glial cell density percentage at day 2 as compared to other days. Whereas the highest increase in ED-1 immunoreactive cells (monocyte/phagocyte marker in rats) was observed at day 2 (23.15%) post-injury. Evaluation of cavity percentage showed a significant difference between weeks 3 and 4 post-injury groups. Conclusions: This study provides a new insight into the multiphase immune response to SCI, including cellular inflammation, macrophages/microglia activation, glial cell density, and cavitation. Better understanding of the inflammatory processes associated with acute SCI would permit the development of better therapeutic strategies. PMID:23999718

  9. Glucose injections into the dorsal hippocampus or dorsolateral striatum of rats prior to T-maze training: Modulation of learning rates and strategy selection

    PubMed Central

    Canal, Clinton E.; Stutz, Sonja J.; Gold, Paul E.

    2005-01-01

    The present experiments examined the effects of injecting glucose into the dorsal hippocampus or dorsolateral striatum on learning rates and on strategy selection in rats trained on a T-maze that can be solved by using either a hippocampus-sensitive place or striatum-sensitive response strategy. Percentage strategy selection on a probe trial (Pcrit) administered after rats achieved criterion (nine of 10 correct choices) varied by group. All groups predominately exhibited a response strategy on a probe trial administered after overtraining, i.e., after 90 trials. In experiment 1, rats that received intrahippocampal glucose injections showed enhanced acquisition of the T-maze and showed increased use of response solutions at Pcrit compared with that of unimplanted and artificial cerebral spinal fluid (aCSF)-treated groups. These findings suggest that glucose enhanced hippocampal functions to accelerate the rate of learning and the early adoption of a response strategy. In experiment 2, rats that received intrastriatal glucose injections exhibited place solutions early in training and reached criterion more slowly than did aCSF controls, with learning rates comparable to those of unoperated and operated-uninjected controls. Relative to unoperated, operated-uninjected and glucose-injected rats, rats that received intrastriatal aCSF injections showed enhanced acquisition of the T-maze and increased use of response solutions at Pcrit. The unexpected enhanced acquisition seen after striatal aCSF injections suggests at least two possible interpretations: (1) aCSF impaired striatal function, thereby releasing competition with the hippocampus and ceding control over learning to the hippocampus during early training trials; and (2) aCSF enhanced striatal functioning to facilitate striatal-sensitive learning. With either interpretation, the results indicate that intrastriatal glucose injections compensated for the aCSF-induced effect. Finally, enhanced acquisition regardless

  10. Effects of Venous Superdrainage and Arterial Supercharging on Dorsal Perforator Flap in a Rat Model

    PubMed Central

    Zheng, Jun; Xi, Shanshan; Ding, Maochao; Li, Hong; Xu, Wei; Tang, Maolin; Chen, Shixin

    2016-01-01

    Objective To comparatively assess the effects of venous superdrainage and arterial supercharging on dorsal perforator flap survival. Materials and Methods Sixty male Sprague-Dawley rats (450–550g) were randomly divided into three groups (n = 20), including control group (Control) and experimental groups A (venous superdrainage, Exp. A) and B (arterial supercharging, Exp. B). At postoperative day 7, survival areas of the flaps were evaluated and all animals underwent angiography. Laser Doppler was used to evaluate flap perfusion from 0h to 7days after surgery. Histology with hematoxylin and eosin staining was used to count microvessels. Tissue of “Choke vessels”was excised for quantification of hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) by western blot assay at 6h and 7days after surgery. Results In the Exp. A group, almost all flaps survived (98.2±1.6%); in the Exp. B and control group, survival areas accounted for 78.8±8.5% and 60.3±7.8%, respectively (P <0.001). In addition, Exp. A animals showed improved anastomosis of choke vessels 2 compared with the Exp. B and Control groups. Furthermore, flap blood flow and partial pressure of oxygen in the Exp. A group were significantly higher compared with values obtained for the Exp. B and Control groups, from 6 hours to 7 days after surgery. More microvessels were found in the Exp. A group (11.65±1.33) than in Exp. B (9.25±0.34) and control (7.25±0.91) animals on POD 7. The relative expression level of HIF-1α and VEGF were significant at 6h and 7days after surgery. Conclusions Venous superdrainage in rat dorsal perforator flap is more effective than arterial supercharging in promoting flap survival, and could effectively alter hemodynamics in the microcirculation and stimulate blood vessel formation. PMID:27513520

  11. Targeted Ablation, Silencing, and Activation Establish Glycinergic Dorsal Horn Neurons as Key Components of a Spinal Gate for Pain and Itch

    PubMed Central

    Foster, Edmund; Wildner, Hendrik; Tudeau, Laetitia; Haueter, Sabine; Ralvenius, William T.; Jegen, Monika; Johannssen, Helge; Hösli, Ladina; Haenraets, Karen; Ghanem, Alexander; Conzelmann, Karl-Klaus; Bösl, Michael; Zeilhofer, Hanns Ulrich

    2015-01-01

    Summary The gate control theory of pain proposes that inhibitory neurons of the spinal dorsal horn exert critical control over the relay of nociceptive signals to higher brain areas. Here we investigated how the glycinergic subpopulation of these neurons contributes to modality-specific pain and itch processing. We generated a GlyT2::Cre transgenic mouse line suitable for virus-mediated retrograde tracing studies and for spatially precise ablation, silencing, and activation of glycinergic neurons. We found that these neurons receive sensory input mainly from myelinated primary sensory neurons and that their local toxin-mediated ablation or silencing induces localized mechanical, heat, and cold hyperalgesia; spontaneous flinching behavior; and excessive licking and biting directed toward the corresponding skin territory. Conversely, local pharmacogenetic activation of the same neurons alleviated neuropathic hyperalgesia and chloroquine- and histamine-induced itch. These results establish glycinergic neurons of the spinal dorsal horn as key elements of an inhibitory pain and itch control circuit. PMID:25789756

  12. Ameliorative Effects of p75NTR-ED-Fc on Axonal Regeneration and Functional Recovery in Spinal Cord-Injured Rats.

    PubMed

    Wang, Yong-Tang; Lu, Xiu-Min; Zhu, Feng; Huang, Peng; Yu, Ying; Long, Zai-Yun; Wu, Ya-Min

    2015-12-01

    As a co-receptor of Nogo-66 receptor (NgR) and a critical receptor for paired immunoglobulin-like receptor (PirB), p75 neurotrophin receptor (p75NTR) mediates the inhibitory effects of myelin-associated inhibitors on axonal regeneration after spinal cord injury. Therefore, the p75NTR antagonist, such as recombinant p75NTR protein or its homogenates may block the inhibitory effects of myelin and promote the axonal regeneration and functional recovery. The purposes of this study are to subclone and express the extracellular domain gene of human p75NTR with IgG-Fc (hp75NTR-ED-Fc) in prokaryotic expression system and investigate the effects of the recombinant protein on axonal regeneration and functional recovery in spinal cord-injured rats. The hp75NTR-ED-Fc coding sequence was amplified from pcDNA-hp75NTR-ED-Fc by polymerase chain reaction (PCR) and subcloned into vector pET32a (+), then the effects of the purified recombinant protein on neurite outgrowth of dorsal root ganglion (DRG) neurons cultured with myelin-associated glycoprotein (MAG) were determined, and the effects of the fusion protein on axonal regeneration, functional recovery, and its possible mechanisms in spinal cord-injured rats were further investigated. The results indicated that the purified infusion protein could promote neurite outgrowth of DRG neurons, promote axonal regeneration and functional recovery, and decrease RhoA activation in spinal cord-injured rats. Taken together, the findings revealed that p75NTR still may be a potential and novel target for therapeutic intervention for spinal cord injury and that the hp75NTR-ED-Fc fusion protein treatment enhances functional recovery by limiting tissue loss and stimulating axonal growth in spinal cord-injured rats, which may result from decreasing the activation of RhoA. PMID:25394381

  13. The role of spinal nitric oxide and glutamate in nociceptive behaviour evoked by high-dose intrathecal morphine in rats.

    PubMed

    Watanabe, Chizuko; Sakurada, Tsukasa; Okuda, Kazuhiro; Sakurada, Chikai; Ando, Ryuichiro; Sakurada, Shinobu

    2003-12-01

    Injection of high-dose of morphine into the spinal lumbar intrathecal (i.t.) space of rats elicits a nociceptive behavioural syndrome characterized by periodic bouts of spontaneous agitation and severe vocalization. The induced behavioural response such as vocalization and agitation was observed dose-dependently by i.t. administration of morphine (125-500 nmol). Pretreatment with naloxone (s.c. and i.t.), an opioid receptor antagonist, failed to reverse the morphine-induced behavioural response. The excitatory effect of morphine was inhibited dose-dependently by pretreatment with 3-((+)2-carboxy-piperazin-4-yl)-propyl-1-phosphonic acid (CPP), a competitive N-methyl-D-aspartate (NMDA) receptor antagonist and MK-801, a non-competitive NMDA receptor antagonist. The non-selective nitric oxide (NO) synthase inhibitor N(G)-nitro L-arginine methyl ester (L-NAME) inhibited dose-dependently the behavioural response to high-dose i.t. morphine (500 nmol), whereas D-NAME was without affecting the response to high-dose i.t. morphine. In the present study, we measured NO metabolites (nitrite/nitrate) in the extracellular fluid of rat dorsal spinal cord using in vivo microdialysis. The i.t. injection of morphine (500 nmol) evoked significant increases in NO metabolites and glutamate from the spinal cord. Not only NO metabolites but also glutamate released by high-dose morphine were reduced significantly by pretreatment with L-NAME (400 nmol). Pretreatment with CPP and MK-801 showed a significant reduction of the NO metabolites and glutamate levels elevated by high-dose i.t. morphine. These results suggest that the excitatory action of high-dose i.t. morphine may be mediated by an NMDA-NO cascade in the spinal cord. PMID:14659510

  14. Locomotor rhythmogenesis in the isolated rat spinal cord: a phase-coupled set of symmetrical flexion–extension oscillators

    PubMed Central

    Juvin, Laurent; Simmers, John; Morin, Didier

    2007-01-01

    The temporal properties of limb motoneuron bursting underlying quadrupedal locomotion were investigated in isolated spinal cord preparations (without or with brainstem attached) taken from 0 to 4-day-old rats. When activated either with differing combinations of N-methyl-d,l-aspartate, serotonin and dopamine, or by electrical stimulation of the brainstem, the spinal cord generated episodes of fictive locomotion with a constant phase relationship between cervical and lumbar ventral root bursts. Alternation occurred between ipsi- and contra-lateral flexor and extensor motor root bursts, and the cervical and lumbar locomotor networks were always active in a diagonal coordination pattern that corresponded to fictive walking. However, unlike typical locomotion in adult animals in which extensor motoneuron bursts vary more with cycle period than flexor bursts, in the isolated neonatal cord, an increase in fictive locomotor speed was associated with a decrease in the durations of both extensor and flexor bursts, at cervical and lumbar levels. To determine whether this symmetry in flexor/extensor phase durations derived from the absence of sensory feedback that is normally provided from the limbs during intact animal locomotion, EMG recordings were made from hindlimb-attached spinal cords during drug-induced locomotor-like movements. Under these conditions, the duration of extensor muscle bursts increased with cycle period, while flexor burst durations now tended to remain constant. Moreover, after a complete dorsal rhizotomy, this extensor dominant pattern was replaced by flexor and extensor muscle bursts of similar duration. In vivo and in vitro experiments were also conducted on older postnatal (P10–12) rats at an age when body-supported adult-like locomotion occurs. Here again, characteristic extensor-dominated burst patterns observed during intact treadmill locomotion were replaced by symmetrical patterns during fictive locomotion expressed by the chemically

  15. Comparison of histopathologic changes following X-irradiation of mid-thoracic and lumbosacral levels of neonatal rat spinal cord

    SciTech Connect

    Heard, J.K.; Gilmore, S.A.

    1985-02-01

    Light microscopic changes were studied in the dorsal funiculi of spinal cords from rats irradiated (4000 R) at 3 days of age and killed from 9-60 days postirradiation (P-I). The irradiated site was limited to a 5-mm length of mid-thoracic spinal cord (T only) in one group of rats, to a 5-mm length of lumbosacral spinal cord (L only) in a second group, and to 5-mm lengths of both mid-thoracic and lumbosacral spinal cord (T/L) in the third group. Changes in the lumbosacral regions were essentially the same in both L only and T/L irradiated groups. These changes included a decreased neuroglial population and a concurrent state of hypomyelination from 9-30 days P-I. In contrast, in the mid-thoracic regions of T only and T/L irradiated groups the decrease in the neuroglial population was obvious only through 13 days P-I, and by 30 days this population resembled that of the controls. The irradiated mid-thoracic areas were hypomyelinated, with the fasciculus gracilis showing a greater degree of hypomyelination than the fasciculus cuneatus. By 25 days P-I, myelination appeared to be normal in these areas. Scattered hemorrhages were noted in both lumbosacral and mid-thoracic regions, but necrotic areas occurred only at the lumbosacral level. In general, the mid-thoracic area appeared to be less sensitive to x-radiation at 3 days of age than the lumbosacral area. These data suggest that there may be marked differences in the developmental states of cells at these two levels at 3 days of age.

  16. Cannabinoids Inhibit Acid-Sensing Ion Channel Currents in Rat Dorsal Root Ganglion Neurons

    PubMed Central

    Qiu, Chun-Yu; Cai, Qi; Zou, Pengcheng; Wu, Heming; Hu, Wang-Ping

    2012-01-01

    Local acidosis has been found in various pain-generating conditions such as inflammation and tissue injury. Cannabinoids exert a powerful inhibitory control over pain initiation via peripheral cognate receptors. However, the peripheral molecular targets responsible for the antinociceptive effects of cannabinoids are still poorly understood. Here, we have found that WIN55,212-2, a cannabinoid receptor agonist, inhibits the activity of native acid-sensing ion channels (ASICs) in rat dorsal root ganglion (DRG) neurons. WIN55,212-2 dose-dependently inhibited proton-gated currents mediated by ASICs. WIN55,212-2 shifted the proton concentration–response curve downwards, with an decrease of 48.6±3.7% in the maximum current response but with no significant change in the EC50 value. The inhibition of proton-gated current induced by WIN55,212-2 was almost completely blocked by the selective CB1 receptor antagonist AM 281, but not by the CB2 receptor antagonist AM630. Pretreatment of forskolin, an AC activator, and the addition of cAMP also reversed the inhibition of WIN55,212-2. Moreover, WIN55,212-2 altered acid-evoked excitability of rat DRG neurons and decreased the number of action potentials induced by acid stimuli. Finally, WIN55,212-2 attenuated nociceptive responses to injection of acetic acid in rats. These results suggest that WIN55,212-2 inhibits the activity of ASICs via CB1 receptor and cAMP dependent pathway in rat primary sensory neurons. Thus, cannabinoids can exert their analgesic action by interaction with ASICs in the primary afferent neurons, which was novel analgesic mechanism of cannabinoids. PMID:23029075

  17. Serotonergic drugs and spinal cord transections indicate that different spinal circuits are involved in external urethral sphincter activity in rats

    PubMed Central

    Chang, Hui-Yi; Cheng, Chen-Li; Chen, Jia-Jin J.; de Groat, William C.

    2011-01-01

    Lower urinary tract function is regulated by spinal and supraspinal reflexes that coordinate the activity of the urinary bladder and external urethral sphincter (EUS). Two types of EUS activity (tonic and bursting) have been identified in rats. This study in urethane-anesthetized female rats used cystometry, EUS electromyography, spinal cord transection (SCT) at different segmental levels, and analysis of the effects of 5-HT1A receptor agonist (8-OH-DPAT) and antagonist (WAY100635) drugs to examine the origin of tonic and bursting EUS activity. EUS activity was elicited by bladder distension or electrical stimulation of afferent axons in the pelvic nerve (pelvic-EUS reflex). Tonic activity evoked by bladder distension was detected in spinal cord-intact rats and after acute and chronic T8–9 or L3–4 SCT but was abolished after L6–S1 SCT. Bursting activity was abolished by all types of SCT except chronic T8–9 transection. 8-OH-DPAT enhanced tonic activity, and WAY100635 reversed the effect of 8-OH-DPAT. The pelvic-EUS reflex consisted of an early response (ER) and late response (LR) when the bladder was distended in spinal cord-intact rats. ER remained after acute or chronic T8–9 and L3–4 SCT, but was absent after L6–S1 SCT. LR occurred only in chronic T8–9 SCT rats where it was enhanced or unmasked by 8-OH-DPAT. The results indicate that spinal serotonergic mechanisms facilitate tonic and bursting EUS activity. The circuitry for generating different patterns of EUS activity appears to be located in different segments of the spinal cord: tonic activity at L6–S1 and bursting activity between T8–9 and L3–4. PMID:17047164

  18. Spinal direct current stimulation modulates the activity of gracile nucleus and primary somatosensory cortex in anaesthetized rats

    PubMed Central

    Aguilar, J; Pulecchi, F; Dilena, R; Oliviero, A; Priori, A; Foffani, G

    2011-01-01

    Abstract Afferent somatosensory activity from the spinal cord has a profound impact on the activity of the brain. Here we investigated the effects of spinal stimulation using direct current, delivered at the thoracic level, on the spontaneous activity and on the somatosensory evoked potentials of the gracile nucleus, which is the main entry point for hindpaw somatosensory signals reaching the brain from the dorsal columns, and of the primary somatosensory cortex in anaesthetized rats. Anodal spinal direct current stimulation (sDCS) increased the spontaneous activity and decreased the amplitude of evoked responses in the gracile nucleus, whereas cathodal sDCS produced the opposite effects. At the level of the primary somatosensory cortex, the changes in spontaneous activity induced by sDCS were consistent with the effects observed in the gracile nucleus, but the changes in cortical evoked responses were more variable and state dependent. Therefore, sDCS can modulate in a polarity-specific manner the supraspinal activity of the somatosensory system, offering a versatile bottom-up neuromodulation technique that could potentially be useful in a number of clinical applications. PMID:21825031

  19. Evaluation of Cisplatin Neurotoxicity in Cultured Rat Dorsal Root Ganglia via Cytosolic Calcium Accumulation

    PubMed Central

    Erol, Kevser; Yiğitaslan, Semra; Ünel, Çiğdem; Kaygısız, Bilgin; Yıldırım, Engin

    2016-01-01

    Background: Calcium homeostasis is considered to be important in antineoplastic as well as in neurotoxic adverse effects of cisplatin. Aims: This study aimed to investigate the role of Ca2+ in cisplatin neurotoxicity in cultured rat dorsal root ganglia (DRG) cells. Study Design: Cell culture study. Methods: DRG cells prepared from 1-day old Sprague-Dawley rats were used to determine the role of Ca2+ in the cisplatin (10–600 μM) neurotoxicity. The cells were incubated with cisplatin plus nimodipine (1–3 μM), dizocilpine (MK-801) (1–3 μM) or thapsigargin (100–300 nM). Toxicity of cisplatinon DRG cells was determined by the MTT assay. Results: The neurotoxicity of cisplatin was significant when used in high concentrations (100–600 μM). Nimodipine (1 μM) but not MK-801 or thapsigargin prevented the neurotoxic effects of 200 μM of cisplatin. Conclusion: Voltage-dependent calcium channels may play a role in cisplatin neurotoxicity. PMID:27403382

  20. Full Inhibition of Spinal FAAH Leads to TRPV1-Mediated Analgesic Effects in Neuropathic Rats and Possible Lipoxygenase-Mediated Remodeling of Anandamide Metabolism

    PubMed Central

    Starowicz, Katarzyna; Makuch, Wioletta; Korostynski, Michal; Malek, Natalia; Slezak, Michal; Zychowska, Magdalena; Petrosino, Stefania; De Petrocellis, Luciano; Cristino, Luigia; Przewlocka, Barbara; Di Marzo, Vincenzo

    2013-01-01

    Neuropathic pain elevates spinal anandamide (AEA) levels in a way further increased when URB597, an inhibitor of AEA hydrolysis by fatty acid amide hydrolase (FAAH), is injected intrathecally. Spinal AEA reduces neuropathic pain by acting at both cannabinoid CB1 receptors and transient receptor potential vanilloid-1 (TRPV1) channels. Yet, intrathecal URB597 is only partially effective at counteracting neuropathic pain. We investigated the effect of high doses of intrathecal URB597 on allodynia and hyperalgesia in rats with chronic constriction injury (CCI) of the sciatic nerve. Among those tested, the 200 µg/rat dose of URB597 was the only one that elevated the levels of the FAAH non-endocannabinoid and anti-inflammatory substrates, oleoylethanolamide (OEA) and palmitoylethanolamide (PEA), and of the endocannabinoid FAAH substrate, 2-arachidonoylglycerol, and fully inhibited thermal and tactile nociception, although in a manner blocked almost uniquely by TRPV1 antagonism. Surprisingly, this dose of URB597 decreased spinal AEA levels. RT-qPCR and western blot analyses demonstrated altered spinal expression of lipoxygenases (LOX), and baicalein, an inhibitor of 12/15-LOX, significantly reduced URB597 analgesic effects, suggesting the occurrence of alternative pathways of AEA metabolism. Using immunofluorescence techniques, FAAH, 15-LOX and TRPV1 were found to co-localize in dorsal spinal horn neurons of CCI rats. Finally, 15-hydroxy-AEA, a 15-LOX derivative of AEA, potently and efficaciously activated the rat recombinant TRPV1 channel. We suggest that intrathecally injected URB597 at full analgesic efficacy unmasks a secondary route of AEA metabolism via 15-LOX with possible formation of 15-hydroxy-AEA, which, together with OEA and PEA, may contribute at producing TRPV1-mediated analgesia in CCI rats. PMID:23573230

  1. The Antinociceptive and Antihyperalgesic Effects of Topical Propofol on Dorsal Horn Neurons in the Rat

    PubMed Central

    Takechi, Kenichi; Carstens, Mirela Iodi; Klein, Amanda H.; Carstens, E.

    2013-01-01

    Background Propofol (2,6-diisopropylphenol) is an IV anesthetic used for general anesthesia. Recent evidence suggests that propofol-anesthetized patients experience less postoperative pain, and that propofol has analgesic properties when applied topically. We presently investigated the antinociceptive effects of topical propofol using behavioral and single-unit electrophysiological methods in rats. Methods In behavioral experiments with rats, we assessed the effect of topical hindpaw application of propofol (1–25%) on heat and mechanically evoked paw withdrawals. In electrophysiology experiments we recorded from lumbar dorsal horn wide dynamic range (WDR)-type neurons in pentobarbital-anesthetized rats. We assessed the effect of topical application of propofol to the ipsilateral hindpaw on neuronal responses elicited by noxious heat, cold and mechanical stimuli. We additionally tested if propofol blocks heat sensitization of paw withdrawals and WDR neuronal responses induced by topical application of allyl isothiocyanate (AITC; mustard oil). Results Topical application of propofol (1–25%) significantly increased the mean latency of the thermally evoked hindpaw withdrawal reflex on the treated (but not opposite) side in a concentration-dependent manner, with no effect on mechanically evoked hindpaw withdrawal thresholds. Propofol also prevented shortening of paw withdrawal latency induced by AITC. In electrophysiological experiments, topical application of 10 and 25% propofol, but not 1% propofol or vehicle (10% intralipid), to the ipsilateral hindpaw significantly attenuated the magnitude of responses of WDR neurons to noxious heating of glabrous hindpaw skin with no significant change in thermal thresholds. Maximal suppression of noxious heat-evoked responses was achieved 15-min after application followed by recovery to the pre-propofol baseline by 30 min. Responses to skin cooling or graded mechanical stimuli were not significantly affected by any

  2. TRANSCRIPT EXPRESSION OF VESICULAR GLUTAMATE TRANSPORTERS IN LUMBAR DORSAL ROOT GANGLIA AND THE SPINAL CORD OF MICE – EFFECTS OF PERIPHERAL AXOTOMY OR HINDPAW INFLAMMATION

    PubMed Central

    MALET, M.; VIEYTES, C. A.; LUNDGREN, K. H.; SEAL, R. P.; TOMASELLA, E.; SEROOGY, K. B.; HÖKFELT, T.; GEBHART, G.F.; BRUMOVSKY, P. R.

    2013-01-01

    Using specific riboprobes, we characterized the expression of VGLUT1-VGLUT3 transcripts in lumbar 4-5 (L4-5) DRGs and the thoracolumbar to lumbosacral spinal cord in male BALB/C mice after a 1- or 3-day hindpaw inflammation, or a 7-day sciatic nerve axotomy. Sham animals were also included. In sham and contralateral L4-5 DRGs of injured mice, VGLUT1-, VGLUT2- and VGLUT3 mRNAs were expressed in ~45%, ~69% or ~17% of neuron profiles (NPs), respectively. VGLUT1 was expressed in large and medium-sized NPs, VGLUT2 in NPs of all sizes, and VGLUT3 in small and medium-sized NPs. In the spinal cord, VGLUT1 was restricted to a number of NPs at thoracolumbar and lumbar segments, in what appears to be the dorsal nucleus of Clarke, and in mid laminae III-IV. In contrast, VGLUT2 was present in numerous NPs at all analyzed spinal segments, except the lateral aspects of the ventral horns, especially at the lumbar enlargement, where it was virtually absent. VGLUT3 was detected in a discrete number of NPs in laminae III-IV of the dorsal horn. Axotomy resulted in a moderate decrease in the number of DRG NPs expressing VGLUT3, whereas VGLUT1 and VGLUT2 were unaffected. Likewise, the percentage of NPs expressing VGLUT transcripts remained unaltered after hindpaw inflammation, both in DRGs and the spinal cord. Altogether, these results confirm previous descriptions on VGLUTs expression in adult mice DRGs, with the exception of VGLUT1, whose protein expression was detected in a lower percentage of mouse DRG NPs. A detailed account on the location of neurons expressing VGLUTs transcripts in the adult mouse spinal cord is also presented. Finally, the lack of change in the number of neurons expressing VGLUT1 and VGLUT2 transcripts after axotomy, as compared to data on protein expression, suggests translational rather than transcriptional regulation of VGLUTs after injury. PMID:23727452

  3. Effect of the synthetic polyamine N,N'-bis-(3-aminopropyl) cyclohexane-1,4-diamine (DCD) on rat spinal cord nociceptive transmission.

    PubMed

    Bilbeny, Norberto; Paeile, Carlos; Contreras, Selfa; Font, María; García, Hernán

    2004-10-01

    In rats submitted to a C-fiber reflex response paradigm, intravenous (i.v.) administration of 2.5, 5 and 10 mg/kg of the synthetic polyamine N,N'-bis-(3-aminopropyl) cyclohexane-1,4-diamine (DCD) dose-dependently reduced both the integrated C reflex responses and wind-up activity. Inhibitory effects of the polyamine on spinal cord nociceptive transmission are likely to be consequence of blockade by extracellular DCD of NMDA receptor channels localized in dorsal horn neurons, although modulatory actions at supraspinal level and at other ion channels could also be possible. PMID:15353239

  4. Alteration of Forebrain Neurogenesis after Cervical Spinal Cord Injury in the Adult Rat

    PubMed Central

    Felix, Marie-Solenne; Popa, Natalia; Djelloul, Mehdi; Boucraut, José; Gauthier, Patrick; Bauer, Sylvian; Matarazzo, Valery A.

    2012-01-01

    Spinal cord injury (SCI) triggers a complex cellular response at the injury site, leading to the formation of a dense scar tissue. Despite this local tissue remodeling, the consequences of SCI at the cellular level in distant rostral sites (i.e., brain), remain unknown. In this study, we asked whether cervical SCI could alter cell dynamics in neurogenic areas of the adult rat forebrain. To this aim, we quantified BrdU incorporation and determined the phenotypes of newly generated cells (neurons, astrocytes, or microglia) during the subchronic and chronic phases of injury. We find that subchronic SCI leads to a reduction of BrdU incorporation and neurogenesis in the olfactory bulb and in the hippocampal dentate gyrus. By contrast, subchronic SCI triggers an increased BrdU incorporation in the dorsal vagal complex of the hindbrain, where most of the newly generated cells are identified as microglia. In chronic condition 90 days after SCI, BrdU incorporation returns to control levels in all regions examined, except in the hippocampus, where SCI produces a long-term reduction of neurogenesis, indicating that this structure is particularly sensitive to SCI. Finally, we observe that SCI triggers an acute inflammatory response in all brain regions examined, as well as a hippocampal-specific decline in BDNF levels. This study provides the first demonstration that forebrain neurogenesis is vulnerable to a distal SCI. PMID:22509147

  5. Imaging corticospinal tract connectivity in injured rat spinal cord using manganese-enhanced MRI

    PubMed Central

    Bilgen, Mehmet

    2006-01-01

    Background Manganese-enhanced MRI (MEI) offers a novel neuroimaging modality to trace corticospinal tract (CST) in live animals. This paper expands this capability further and tests the utility of MEI to image axonal fiber connectivity in CST of injured spinal cord (SC). Methods A rat was injured at the thoracic T4 level of the SC. The CST was labeled with manganese (Mn) injected intracortically at two weeks post injury. Next day, the injured SC was imaged using MEI and diffusion tensor imaging (DTI) modalities. Results In vivo MEI data obtained from cervical SC confirmed that CST was successfully labeled with Mn. Ex vivo MEI data obtained from excised SC depicted Mn labeling of the CST in SC sections caudal to the lesion, which meant that Mn was transported through the injury, possibly mediated by viable CST fibers present at the injury site. Examining the ex vivo data from the injury epicenter closely revealed a thin strip of signal enhancement located ventrally between the dorsal horns. This enhancement was presumably associated with the Mn accumulation in these intact fibers projecting caudally as part of the CST. Additional measurements with DTI supported this view. Conclusion Combining these preliminary results collectively demonstrated the feasibility of imaging fiber connectivity in experimentally injured SC using MEI. This approach may play important role in future investigations aimed at understanding the neuroplasticity in experimental SCI research. PMID:17112375

  6. Modeling zero-lag synchronization of dorsal horn neurons during the traveling of electrical waves in the cat spinal cord

    PubMed Central

    Kato, Hideyuki; Cuellar, Carlos A; Delgado-Lezama, Rodolfo; Rudomin, Pablo; Jimenez-Estrada, Ismael; Manjarrez, Elias; Mirasso, Claudio R

    2013-01-01

    The first electrophysiological evidence of the phenomenon of traveling electrical waves produced by populations of interneurons within the spinal cord was reported by our interdisciplinary research group. Two interesting observations derive from this study: first, the negative spontaneous cord dorsum potentials (CDPs) that are superimposed on the propagating sinusoidal electrical waves are not correlated with any scratching phase; second, these CDPs do not propagate along the lumbosacral spinal segments, but they appear almost simultaneously at different spinal segments. The aim of this study was to provide experimental data and a mathematical model to explain the simultaneous occurrence of traveling waves and the zero-lag synchronization of some CDPs. PMID:24303110

  7. Sprouty2 in the Dorsal Hippocampus Regulates Neurogenesis and Stress Responsiveness in Rats

    PubMed Central

    Dow, Antonia L.; Lin, Tiffany V.; Chartoff, Elena H.; Potter, David; McPhie, Donna L.; Van’t Veer, Ashlee V.; Knoll, Allison T.; Lee, Kristen N.; Neve, Rachael L.; Patel, Tarun B.; Ongur, Dost; Cohen, Bruce M.; Carlezon, William A.

    2015-01-01

    Both the development and relief of stress-related psychiatric conditions such as major depression (MD) and post-traumatic stress disorder (PTSD) have been linked to neuroplastic changes in the brain. One such change involves the birth of new neurons (neurogenesis), which occurs throughout adulthood within discrete areas of the mammalian brain, including the dorsal hippocampus (HIP). Stress can trigger MD and PTSD in humans, and there is considerable evidence that it can decrease HIP neurogenesis in laboratory animals. In contrast, antidepressant treatments increase HIP neurogenesis, and their efficacy is eliminated by ablation of this process. These findings have led to the working hypothesis that HIP neurogenesis serves as a biomarker of neuroplasticity and stress resistance. Here we report that local alterations in the expression of Sprouty2 (SPRY2), an intracellular inhibitor of growth factor function, produces profound effects on both HIP neurogenesis and behaviors that reflect sensitivity to stressors. Viral vector-mediated disruption of endogenous Sprouty2 function (via a dominant negative construct) within the dorsal HIP of adult rats stimulates neurogenesis and produces signs of stress resilience including enhanced extinction of conditioned fear. Conversely, viral vector-mediated elevation of SPRY2 expression intensifies the behavioral consequences of stress. Studies of these manipulations in HIP primary cultures indicate that SPRY2 negatively regulates fibroblast growth factor-2 (FGF2), which has been previously shown to produce antidepressant- and anxiolytic-like effects via actions in the HIP. Our findings strengthen the relationship between HIP plasticity and stress responsiveness, and identify a specific intracellular pathway that could be targeted to study and treat stress-related disorders. PMID:25822989

  8. Effects of electrical stimulation of the dorsal raphe nucleus on local cerebral blood flow in the rat

    SciTech Connect

    Bonvento, G.; Lacombe, P.; Seylaz, J. )

    1989-06-01

    We have studied the effects of electrical stimulation of the dorsal raphe nucleus on local cerebral blood flow (LCBF), as assessed by the quantitative ({sup 14}C)-iodoantipyrine autoradiographic technique. Stimulation of the dorsal raphe nucleus in the alpha-chloralose anesthetized rat caused a significant decrease in LCBF, ranging from -13 to -26% in 24 brain structures out of 33 investigated. The most pronounced decreases (-23 to -26%) were observed in the accumbens, amygdaloid, interpeduncular nuclei and in the median raphe nucleus, limbic system relays. The decreases also concerned cortical regions and the extrapyramidal system. These results indicate that activation of ascending serotonergic system produces a vasoconstriction and that the dorsal raphe nucleus has a widespread modulatory influence on the cerebral circulation.

  9. Bone blood flow after spinal paralysis in the rat

    SciTech Connect

    Takahashi, H.; Yamamuro, T.; Okumura, H.; Kasai, R.; Tada, K. )

    1990-05-01

    The goal of this study was to investigate the acute and chronic effects of paralysis induced by spinal cord section or sciatic neurotomy on bone blood flow in the rat. Regional bone blood flow was measured in the early stage with the hydrogen washout technique and the change of whole bone blood flow was measured in the early and the late stages with the radioactive microsphere technique. Four to 6 h after cordotomy at the level of the 13th thoracic vertebra, the regional bone blood flow in the denervated tibia increased significantly (p less than 0.01). After hemicordotomy with rhizotomy at the same level, the regional bone blood flow in the denervated tibia increased significantly (p less than 0.05) 6 h postoperatively. The whole bone blood flow in the denervated tibia had also increased significantly (p less than 0.05) at 6 h and at 4 and 12 weeks postoperatively. After sciatic neurotomy, the regional and the whole bone blood flow in the paralytic tibia did not change significantly. The present study demonstrated that monoplegic paralysis caused an increase in bone blood flow in the denervated hind limb from a very early stage. It was suggested that the spinal nervous system contributed to the control of bone blood flow.

  10. Flexibilide Obtained from Cultured Soft Coral Has Anti-Neuroinflammatory and Analgesic Effects through the Upregulation of Spinal Transforming Growth Factor-β1 in Neuropathic Rats

    PubMed Central

    Chen, Nan-Fu; Huang, Shi-Ying; Lu, Ching-Hsiang; Chen, Chun-Lin; Feng, Chien-Wei; Chen, Chun-Hong; Hung, Han-Chun; Lin, Yen-You; Sung, Ping-Jyun; Sung, Chun-Sung; Yang, San-Nan; Wang, Hui-Min David; Chang, Yu-Chia; Sheu, Jyh-Horng; Chen, Wu-Fu; Wen, Zhi-Hong

    2014-01-01

    Chronic neuroinflammation plays an important role in the development and maintenance of neuropathic pain. The compound flexibilide, which can be obtained from cultured soft coral, possesses anti-inflammatory and analgesic effects in the rat carrageenan peripheral inflammation model. In the present study, we investigated the antinociceptive properties of flexibilide in the rat chronic constriction injury (CCI) model of neuropathic pain. First, we found that a single intrathecal (i.t.) administration of flexibilide significantly attenuated CCI-induced thermal hyperalgesia at 14 days after surgery. Second, i.t. administration of 10-μg flexibilide twice daily was able to prevent the development of thermal hyperalgesia and weight-bearing deficits in CCI rats. Third, i.t. flexibilide significantly inhibited CCI-induced activation of microglia and astrocytes, as well as the upregulated proinflammatory enzyme, inducible nitric oxide synthase, in the ipsilateral spinal dorsal horn. Furthermore, flexibilide attenuated the CCI-induced downregulation of spinal transforming growth factor-β1 (TGF-β1) at 14 days after surgery. Finally, i.t. SB431542, a selective inhibitor of TGF-β type I receptor, blocked the analgesic effects of flexibilide in CCI rats. Our results suggest that flexibilide may serve as a therapeutic agent for neuropathic pain. In addition, spinal TGF-β1 may be involved in the anti-neuroinflammatory and analgesic effects of flexibilide. PMID:24979268

  11. Patterns of Phrenic Nerve Discharge after Complete High Cervical Spinal Cord Injury in the Decerebrate Rat.

    PubMed

    Ghali, Michael George Zaki; Marchenko, Vitaliy

    2016-06-15

    Studies conducted since the second half of the 19th century have revealed spontaneous as well as pharmacologically induced phasic/rhythmic discharge in spinal respiratory motor outputs of cats, dogs, rabbits, and neonatal rats following high cervical transection (Tx). The extent to which these various studies validate the existence of a true spinal respiratory rhythm generator remains debated. In this set of studies, we seek to characterize patterns of spontaneous phasic/rhythmic, asphyxia-induced, and pharmacologically induced activity occurring in phrenic nerve (PhN) discharge after complete high cervical (C1-C2) spinal cord transection. Experiments were performed on 20 unanesthetized decerebrate Sprague-Dawley adult male rats. Patterns of spontaneous activity after spinalization included tonic, phasic, slow oscillatory, and long-lasting tonic discharges. Topical application of antagonists of GABAA and glycine receptors to C1- and C2- spinal segments induced left-right synchronized phasic decrementing activity in PhN discharge that was abolished by an additional C2Tx. Asphyxia elicited increases in tonic activity and left-right synchronized gasp-like bursts in PhN discharge, demonstrating the presence of spinal circuits that may underlie a spinal gasping-like mechanism. We conclude that intrinsic slow oscillators and a phasic burst/rhythm generator exist in the spinal cord of the adult rat. If present in humans, this mechanism may be exploited to recover respiratory function in patients sustaining severe spinal cord injury. PMID:26239508

  12. Contusive spinal cord injury evokes localized changes in NADPH-d activity but extensive changes in Fos-like immunoreactivity in the rat.

    PubMed

    Allbutt, Haydn N; Siddall, Phillip J; Keay, Kevin A

    2007-09-01

    The histological detection of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d), a marker for nitric oxide-producing cells, was used to evaluate ongoing changes in the neural biochemistry of the rat spinal cord 1 week following contusive spinal cord injury (SCI). In addition, the immunohistochemical detection of the immediate-early gene c-fos was used to identify basal patterns of neural activity at this time. The numbers and laminar locations of NADPH-d- and c-fos-positive cells were examined in spinal segments adjacent to the site of injury (T12-S3) as well as those distant from the injury (C3-C5) in both SCI and un-injured rats. Our data show that contusive SCI results in a significant reduction in NADPH-d labelling in the superficial dorsal horn, and a significant increase in NADPH-d expression in small bipolar neurons and large motoneurons in the ventral horn at the site of the injury. In spinal segments distant to the injury site (C3-C5), NADPH-d activity did not differ from that of uninjured controls. Furthermore, significant reductions in the levels of c-fos expression were observed in SCI rats, in spinal segments both at and distant to the site of injury for all spinal laminae. The only exception was a dramatic increase observed in the sacral parasympathetic nucleus. These data suggest that increased NADPH-d expression is related to conditions specific to the site of injury, whereas the changes in c-fos expression probably indicate more global changes in neuronal activity following SCI. PMID:17584182

  13. Loss of inhibitory tone on spinal cord dorsal horn spontaneously and nonspontaneously active neurons in a mouse model of neuropathic pain.

    PubMed

    Medrano, Maria Carmen; Dhanasobhon, Dhanasak; Yalcin, Ipek; Schlichter, Rémy; Cordero-Erausquin, Matilde

    2016-07-01

    Plasticity of inhibitory transmission in the spinal dorsal horn (SDH) is believed to be a key mechanism responsible for pain hypersensitivity in neuropathic pain syndromes. We evaluated this plasticity by recording responses to mechanical stimuli in silent neurons (nonspontaneously active [NSA]) and neurons showing ongoing activity (spontaneously active [SA]) in the SDH of control and nerve-injured mice (cuff model). The SA and NSA neurons represented 59% and 41% of recorded neurons, respectively, and were predominantly wide dynamic range (WDR) in naive mice. Nerve-injured mice displayed a marked decrease in the mechanical threshold of the injured paw. After nerve injury, the proportion of SA neurons was increased to 78%, which suggests that some NSA neurons became SA. In addition, the response to touch (but not pinch) was dramatically increased in SA neurons, and high-threshold (nociceptive specific) neurons were no longer observed. Pharmacological blockade of spinal inhibition with a mixture of GABAA and glycine receptor antagonists significantly increased responses to innocuous mechanical stimuli in SA and NSA neurons from sham animals, but had no effect in sciatic nerve-injured animals, revealing a dramatic loss of spinal inhibitory tone in this situation. Moreover, in nerve-injured mice, local spinal administration of acetazolamide, a carbonic anhydrase inhibitor, restored responses to touch similar to those observed in naive or sham mice. These results suggest that a shift in the reversal potential for anions is an important component of the abnormal mechanical responses and of the loss of inhibitory tone recorded in a model of nerve injury-induced neuropathic pain. PMID:26934510

  14. Evaluation of Five Tests for Sensitivity to Functional Deficits following Cervical or Thoracic Dorsal Column Transection in the Rat

    PubMed Central

    Eggers, Ruben; Tuinenbreijer, Lizz; Kouwenhoven, Dorette; Verhaagen, Joost; Mason, Matthew R. J.

    2016-01-01

    The dorsal column lesion model of spinal cord injury targets sensory fibres which originate from the dorsal root ganglia and ascend in the dorsal funiculus. It has the advantages that fibres can be specifically traced from the sciatic nerve, verifiably complete lesions can be performed of the labelled fibres, and it can be used to study sprouting in the central nervous system from the conditioning lesion effect. However, functional deficits from this type of lesion are mild, making assessment of experimental treatment-induced functional recovery difficult. Here, five functional tests were compared for their sensitivity to functional deficits, and hence their suitability to reliably measure recovery of function after dorsal column injury. We assessed the tape removal test, the rope crossing test, CatWalk gait analysis, and the horizontal ladder, and introduce a new test, the inclined rolling ladder. Animals with dorsal column injuries at C4 or T7 level were compared to sham-operated animals for a duration of eight weeks. As well as comparing groups at individual timepoints we also compared the longitudinal data over the whole time course with linear mixed models (LMMs), and for tests where steps are scored as success/error, using generalized LMMs for binomial data. Although, generally, function recovered to sham levels within 2–6 weeks, in most tests we were able to detect significant deficits with whole time-course comparisons. On the horizontal ladder deficits were detected until 5–6 weeks. With the new inclined rolling ladder functional deficits were somewhat more consistent over the testing period and appeared to last for 6–7 weeks. Of the CatWalk parameters base of support was sensitive to cervical and thoracic lesions while hind-paw print-width was affected by cervical lesion only. The inclined rolling ladder test in combination with the horizontal ladder and the CatWalk may prove useful to monitor functional recovery after experimental treatment in this

  15. Evaluation of Five Tests for Sensitivity to Functional Deficits following Cervical or Thoracic Dorsal Column Transection in the Rat.

    PubMed

    Fagoe, Nitish D; Attwell, Callan L; Eggers, Ruben; Tuinenbreijer, Lizz; Kouwenhoven, Dorette; Verhaagen, Joost; Mason, Matthew R J

    2016-01-01

    The dorsal column lesion model of spinal cord injury targets sensory fibres which originate from the dorsal root ganglia and ascend in the dorsal funiculus. It has the advantages that fibres can be specifically traced from the sciatic nerve, verifiably complete lesions can be performed of the labelled fibres, and it can be used to study sprouting in the central nervous system from the conditioning lesion effect. However, functional deficits from this type of lesion are mild, making assessment of experimental treatment-induced functional recovery difficult. Here, five functional tests were compared for their sensitivity to functional deficits, and hence their suitability to reliably measure recovery of function after dorsal column injury. We assessed the tape removal test, the rope crossing test, CatWalk gait analysis, and the horizontal ladder, and introduce a new test, the inclined rolling ladder. Animals with dorsal column injuries at C4 or T7 level were compared to sham-operated animals for a duration of eight weeks. As well as comparing groups at individual timepoints we also compared the longitudinal data over the whole time course with linear mixed models (LMMs), and for tests where steps are scored as success/error, using generalized LMMs for binomial data. Although, generally, function recovered to sham levels within 2-6 weeks, in most tests we were able to detect significant deficits with whole time-course comparisons. On the horizontal ladder deficits were detected until 5-6 weeks. With the new inclined rolling ladder functional deficits were somewhat more consistent over the testing period and appeared to last for 6-7 weeks. Of the CatWalk parameters base of support was sensitive to cervical and thoracic lesions while hind-paw print-width was affected by cervical lesion only. The inclined rolling ladder test in combination with the horizontal ladder and the CatWalk may prove useful to monitor functional recovery after experimental treatment in this

  16. Spinal CPEB-mtROS-CBP signaling pathway contributes to perineural HIV gp120 with ddC-related neuropathic pain in rats.

    PubMed

    Iida, Takafumi; Yi, Hyun; Liu, Shue; Huang, Wan; Kanda, Hirotsugu; Lubarsky, David A; Hao, Shuanglin

    2016-07-01

    Human immunodeficiency virus (HIV) patients treated with nucleoside reverse transcriptase inhibitors (NRTIs), have been known to develop neuropathic pain. While there has been a major shift away from some neurotoxic NRTIs in current antiretroviral therapy, a large number of HIV patients alive today have previously received them, and many have developed painful peripheral neuropathy. The exact mechanisms by which HIV with NRTIs contribute to the development of neuropathic pain are not known. Previous studies suggest that cytoplasmic polyadenylation element-binding protein (CPEB), reactive oxygen species (ROS), and cAMP-response element-binding protein (CREB)-binding protein (CBP), are involved in the neuroimmunological diseases including inflammatory/neuropathic pain. In this study, we investigated the role of CPEB, mitochondrial ROS (mtROS), or CBP in neuropathic pain induced by HIV envelope protein gp120 combined with antiretroviral drug. The application of recombinant gp120 into the sciatic nerve plus systemic ddC (one of NRTIs) induced mechanical allodynia. Knockdown of CPEB or CBP using intrathecal antisense oligodeoxynucleotide (AS-ODN) reduced mechanical allodynia. Intrathecal mitochondrial superoxide scavenger mito-tempol (Mito-T) increased mechanical withdrawal threshold. Knockdown of CPEB using intrathecal AS-ODN, reduced the up-regulated mitochondrial superoxide in the spinal dorsal horn in rats with gp120 combined with ddC. Intrathecal Mito-T lowered the increased expression of CBP in the spinal dorsal horn. Immunostaining studies showed that neuronal CPEB positive cells were co-localized with MitoSox positive profiles, and that MitoSox positive profiles were co-localized with neuronal CBP. Our studies suggest that neuronal CPEB-mtROS-CBP pathway in the spinal dorsal horn, plays an important role in the gp120/ddC-induced neuropathic pain in rats. PMID:27090160

  17. Formation of the central canal and dorsal glial septum in the spinal cord of the domestic cat.

    PubMed Central

    Böhme, G

    1988-01-01

    Development of the neural tube results in a relative reduction of its lumen accompanied by an increasing thickness of its wall. The central canal measures only about one fifth of that of the former neural canal. This has been said to be the result of an obliteration or fusion of a part of the lumen. This transformation of the central canal takes place between fetal days 28 and 34 in the cat and is characterised by an elongation and shifting of the dorsal ependymal matrix cells and by an apposition of the lateral walls in the same region. It is suggested that the increase in size of the dorsal funiculi causes the elongation of the ependymal cells, the basal processes of which remain to form the dorsal glial septum. The proliferation of neurons and the resultant growth of the dorsal grey horns is believed to be responsible for the narrowing of the lumen. The lumen-contacting matrix cells are displaced from the former surface. These 'blast' cells develop into neurons or glial cells. Until two or three months after birth there is a small wedge-shaped area in the dorsal wall of the central canal which consists of fetal matrix cells with long tapering basal processes extending into the glial septum. After this date the matrix is exhausted and the ependyma forms the complete lining of the surface of the central canal. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 11 Fig. 12 PMID:3248971

  18. Activation of TRPV1 by capsaicin induces functional Kinin B1 receptor in rat spinal cord microglia

    PubMed Central

    2012-01-01

    Background The kinin B1 receptor (B1R) is upregulated by pro-inflammatory cytokines and oxydative stress, which are enhanced by transient receptor potential vanilloid subtype 1 (TRPV1) activation. To examine the link between TRPV1 and B1R in inflammatory pain, this study aimed to determine the ability of TRPV1 to regulate microglial B1R expression in the spinal cord dorsal horn, and the underlying mechanism. Methods B1R expression (mRNA, protein and binding sites) was measured in cervical, thoracic and lumbar spinal cord in response to TRPV1 activation by systemic capsaicin (1-50 mg/kg, s.c) in rats pre-treated with TRPV1 antagonists (capsazepine or SB-366791), the antioxidant N-acetyl-L-cysteine (NAC), or vehicle. B1R function was assessed using a tail-flick test after intrathecal (i.t.) injection of a selective B1R agonist (des-Arg9-BK), and its microglial localization was investigated by confocal microscopy with the selective fluorescent B1R agonist, [Nα-bodipy]-des-Arg9-BK. The effect of i.t. capsaicin (1 μg/site) was also investigated. Results Capsaicin (10 to 50 mg/kg, s.c.) enhanced time-dependently (0-24h) B1R mRNA levels in the lumbar spinal cord; this effect was prevented by capsazepine (10 mg/kg, i.p.; 10 μg/site, i.t.) and SB-366791 (1 mg/kg, i.p.; 30 μg/site, i.t.). Increases of B1R mRNA were correlated with IL-1β mRNA levels, and they were significantly less in cervical and thoracic spinal cord. Intrathecal capsaicin (1 μg/site) also enhanced B1R mRNA in lumbar spinal cord. NAC (1 g/kg/d × 7 days) prevented B1R up-regulation, superoxide anion production and NF-kB activation induced by capsaicin (15 mg/kg). Des-Arg9-BK (9.6 nmol/site, i.t.) decreased by 25-30% the nociceptive threshold at 1 min post-injection in capsaicin-treated rats (10-50 mg/kg) while it was without effect in control rats. Des-Arg9-BK-induced thermal hyperalgesia was blocked by capsazepine, SB-366791 and by antagonists/inhibitors of B1R (SSR240612, 10 mg/kg, p.o.), glutamate

  19. A PARYLENE-BASED MICROELECTRODE ARRAY IMPLANT FOR SPINAL CORD STIMULATION IN RATS

    PubMed Central

    Nandra, Mandheerej. S.; Lavrov, Igor A.; Edgerton, V. Reggie; Tai, Yu-Chong

    2011-01-01

    The design and fabrication of an epidural spinal cord implant using a parylene-based microelectrode array is presented. Rats with hindlimb paralysis from a complete spinal cord transection were implanted with the device and studied for up to eight weeks, where we have demonstrated recovery of hindlimb stepping functionality through pulsed stimulation. The microelectrode array allows for a high degree of freedom and specificity in selecting the site of stimulation compared to wire-based implants, and triggers varied biological responses that can lead to an increased understanding of the spinal cord and locomotion recovery for victims of spinal cord injury. PMID:21841938

  20. Dorsal Cochlear Nucleus of the Rat: Representation of Complex Sounds in Ears Damaged by Acoustic Trauma.

    PubMed

    Li, Yang; Ropp, Tessa-Jonne F; May, Bradford J; Young, Eric D

    2015-08-01

    Acoustic trauma damages the cochlea but secondarily modifies circuits of the central auditory system. Changes include decreases in inhibitory neurotransmitter systems, degeneration and rewiring of synaptic circuits, and changes in neural activity. Little is known about the consequences of these changes for the representation of complex sounds. Here, we show data from the dorsal cochlear nucleus (DCN) of rats with a moderate high-frequency hearing loss following acoustic trauma. Single-neuron recording was used to estimate the organization of neurons' receptive fields, the balance of inhibition and excitation, and the representation of the spectra of complex broadband stimuli. The complex stimuli had random spectral shapes (RSSs), and the responses were fit with a model that allows the quality of the representation and its degree of linearity to be estimated. Tone response maps of DCN neurons in rat are like those in other species investigated previously, suggesting the same general organization of this nucleus. Following acoustic trauma, abnormal response types appeared. These can be interpreted as reflecting degraded tuning in auditory nerve fibers plus loss of inhibitory inputs in DCN. Abnormal types are somewhat more prevalent at later times (103-376 days) following the exposure, but not significantly so. Inhibition became weaker in post-trauma neurons that retained inhibitory responses but also disappeared in many neurons. The quality of the representation of spectral shape, measured by sensitivity to the spectral shapes of RSS stimuli, was decreased following trauma; in fact, neurons with abnormal response types responded mainly to overall stimulus level, and not spectral shape. PMID:25967754

  1. Glucose effects on gastric motility and tone evoked from the rat dorsal vagal complex.

    PubMed

    Ferreira, M; Browning, K N; Sahibzada, N; Verbalis, J G; Gillis, R A; Travagli, R A

    2001-10-01

    1. To examine the effects of glucose on the central components of the vago-vagal reflex control of gastric function, we performed both in vivo and in vitro experiments on neurones in the medial nucleus of the tractus solitarius (mNTS) and in the dorsal motor nucleus of the vagus (DMV). 2. In the in vivo anaesthetized rat preparation, unilateral microinjection of D-glucose (10 or 50 mM (60 nl)(-1)) in mNTS produced inhibition of gastric motility and an increase in intragastric pressure. D-glucose had no effect in the DMV. 3. In the in vitro rat brainstem slice preparation, whole-cell recordings of DMV neurones showed that increasing the glucose concentration of the perfusion solution from 5 mM to 15 or 30 mM produced outward currents of 35 +/- 5 pA (n = 7) and 51 +/- 10 pA (n = 11), respectively. These were blocked by tetrodotoxin and picrotoxin, indicating that glucose was acting indirectly to cause the release of GABA. Decreasing the glucose concentration of the perfusing solution by one-half produced an inward current of 36 +/- 5 pA (n = 7). 4. Stimulation of the NTS evoked inhibitory postsynaptic currents (IPSCs) in DMV neurones. The amplitude of the evoked IPSCs was positively correlated with glucose concentration. Perfusion with the ATP-sensitive K(+) (K(ATP)) channel opener diazoxide mimicked the effect of reduced glucose, while perfusion with the K(ATP) channel blocker glibenclamide mimicked the effects of increased glucose. 5. Our data indicate that glucose had no direct excitatory effect on DMV neurones, but DMV neurones appear to be affected by an action of glucose on cell bodies of mNTS neurones via effects on an ATP-sensitive potassium channel. PMID:11579164

  2. Inflammatory mediators release calcitonin gene-related peptide from dorsal root ganglion neurons of the rat.

    PubMed

    Averbeck, B; Izydorczyk, I; Kress, M

    2000-01-01

    The interactions between the inflammatory mediators bradykinin, serotonin, prostaglandin E(2) and acid pH were studied in rat dorsal root ganglion neurons in culture. For this purpose, the cultures were stimulated by inflammatory mediators (bradykinin, serotonin, prostaglandin E(2), 10(-5)M each) or acid solution (pH 6.1) for 5 min and the content of calcitonin gene-related peptide was determined in the supernatant before, during and after stimulation, using an enzyme immunoassay. Acid solution resulted in a threefold increase of the basal calcitonin gene-related peptide release which was entirely dependent on the presence of extracellular calcium. The release could not be blocked by the addition of the capsaicin antagonist capsazepine (10(-5)M). Bradykinin (10(-5)M) caused a 50% increase of the basal calcitonin gene-related peptide release which was again dependent on the presence of extracellular calcium, whereas serotonin and prostaglandin E(2) were each ineffective at 10(-5)M concentration. The combination of bradykinin, serotonin and prostaglandin E(2) led to a fivefold increase of the calcitonin gene-related peptide release which could not be further enhanced by acidification. The competitive capsaicin receptor antagonist capsazepine (10(-5)M) significantly reduced the release induced by the combination of bradykinin, serotonin and prostaglandin E(2). It is suggested that the inflammatory mediators co-operate and together may act as endogenous agonists at the capsaicin receptor to cause calcium influx and consecutive neuropeptide release. PMID:10858619

  3. Dorsal striatal dopamine depletion impairs both allocentric and egocentric navigation in rats.

    PubMed

    Braun, Amanda A; Graham, Devon L; Schaefer, Tori L; Vorhees, Charles V; Williams, Michael T

    2012-05-01

    Successful navigation requires interactions among multiple but overlapping neural pathways mediating distinct capabilities, including egocentric (self-oriented, route-based) and allocentric (spatial, map-based) learning. Route-based navigation has been shown to be impaired following acute exposure to the dopaminergic (DA) drugs (+)-methamphetamine and (+)-amphetamine, but not the serotoninergic (5-HT) drugs (±)-3,4-methylenedioxymethamphetamine or (±)-fenfluramine. The dopaminergic-rich neostriatum is involved in both allocentric and egocentric navigation. This experiment tested whether dorsal striatal DA loss using bilateral 6-hydroxydopamine (6-OHDA) injections impaired one or both types of navigation. Two weeks following 6-OHDA injections, rats began testing in the Cincinnati water maze (CWM) followed by the Morris water maze (MWM) for route-based and spatial navigation, respectively. 6-OHDA treatment significantly increased latency and errors in the CWM and path length, latency, and cumulative distance in the MWM with no difference on cued MWM trials. Neostriatal DA levels were reduced by 80% at 2 and 7 weeks post-treatment. In addition, 6-OHDA increased DA turnover and decreased norepinephrine (NE) levels. 6-OHDA injections did not alter monoamine levels in the prefrontal cortex. The data support that neostriatal DA modulates both types of navigation. PMID:22465436

  4. Decreased voltage-gated potassium currents in rat dorsal root ganglion neurons after chronic constriction injury.

    PubMed

    Xiao, Yun; Wu, Yang; Zhao, Bo; Xia, Zhongyuan

    2016-01-20

    Voltage-gated potassium channels (KV) regulate pain transmission by controlling neuronal excitability. Changes in KV expression patterns may thus contribute toward hyperalgesia following nerve injury. The aim of this study was to characterize KV current density in dorsal root ganglion (DRG) neurons following chronic constriction injury (CCI) of the right sciatic nerve, a robust model of post-traumatic neuropathic pain. The study examined changes in small-diameter potassium ion currents (<30 µm) in neurons in the L4-L6 DRG following CCI by whole-cell patch-clamping and the association with post-CCI mechanical and thermal nociceptive thresholds. Compared with the control group, 7 days after CCI, the mechanical force and temperature required to elicit ipsilateral foot withdrawal decreased significantly, indicating tactile allodynia and thermal hyperalgesia. Post-CCI neurons had a significantly lower rheobase current and depolarized resting membrane potential than controls, suggesting KV current downregulation. Some ipsilateral DRG neurons also had spontaneous action potentials and repetitive firing. There was a 55% reduction in the total KV current density caused by a 55% decrease in the sustained delayed rectifier potassium ion current (IK) density and a 17% decrease in the transient A-type potassium ion current (IA) density. These results indicated that changes in DRG neuron IK and IA current density and concomitant afferent hyperexcitability may contribute toward neuropathic pain following injury. The rat CCI model may prove valuable for examining pathogenic mechanisms and potential therapies, such as KV channel modulators. PMID:26671526

  5. Global analysis of transcriptome in dorsal root ganglia following peripheral nerve injury in rats.

    PubMed

    Gong, Leilei; Wu, Jiancheng; Zhou, Songlin; Wang, Yaxian; Qin, Jing; Yu, Bin; Gu, Xiaosong; Yao, Chun

    2016-09-01

    Peripheral nervous system has intrinsic regeneration ability after injury, accompanied with the coordination of numerous cells, molecules and signaling pathways. These post-injury biological changes are complex with insufficient understanding. Thus, to obtain a global perspective of changes following nerve injury and to elucidate the mechanisms underlying nerve regeneration are of great importance. By RNA sequencing, we detected transcriptional changes in dorsal root ganglia (DRG) neurons at 0 h, 3 h, 9 h, 1 d, 4 d and 7 d following sciatic nerve crush injury in rats. Differentially expressed genes were then selected and classified into major clusters according to their expression patterns. Cluster 2 (with genes high expressed before 9 h and then down expressed) and cluster 6 (combination of cluster 4 and 5 with genes low expressed before 1 d and then up expressed) were underwent GO annotation and KEGG pathway analysis. Gene act networks were then constructed for these two clusters and the expression of pivotal genes was validated by quantitative real-time PCR. This study provided valuable information regarding the transcriptome changes in DRG neurons following nerve injury, identified potential genes that could be used for improving axon regeneration after nerve injury, and facilitated to elucidate the biological process and molecular mechanisms underlying peripheral nerve injury. PMID:27450809

  6. Tonic GABAA Receptor-Mediated Inhibition in the Rat Dorsal Motor Nucleus of the Vagus

    PubMed Central

    Gao, Hong

    2010-01-01

    Type A γ-aminobutyric acid (GABAA) receptors expressed in the dorsal motor nucleus of vagus (DMV) critically regulate the activity of vagal motor neurons and, by inference, the gastrointestinal (GI) tract. Two types of GABAA receptor-mediated inhibition have been identified in the brain, represented by phasic (Iphasic) and tonic (Itonic) inhibitory currents. The hypothesis that Itonic regulates neuron activity was tested in the DMV using whole cell patch-clamp recordings in transverse brain stem slices from rats. An Itonic was present in a subset of DMV neurons, which was determined to be mediated by different receptors than those mediating fast, synaptic currents. Preapplication of tetrodotoxin significantly decreased the resting Itonic amplitude in DMV neurons, suggesting that most of the current was due to action potential (AP)–dependent GABA release. Blocking GABA transport enhanced Itonic and multiple GABA transporters cooperated to regulate Itonic. The Itonic was composed of both a gabazine-insensitive component that was nearly saturated under basal conditions and a gabazine-sensitive component that was activated when extracellular GABA concentration was elevated. Perfusion of THIP (10 μM) significantly increased Itonic amplitude without increasing Iphasic amplitude. The Itonic played a major role in determining the overall excitability of DMV neurons by contributing to resting membrane potential and AP frequency. Our results indicate that Itonic contributes to DMV neuron membrane potential and activity and is thus an important regulator of vagally mediated GI function. PMID:20018836

  7. Motor strategies used by rats spinalized at birth to maintain stance in response to imposed perturbations

    PubMed Central

    Giszter, Simon F; Davies, Michelle R; Graziani, Virginia

    2010-01-01

    Some rats spinalized P1/P2 achieve autonomous weight supported locomotion and quiet stance as adults. We used force platforms and robot applied perturbations to test such spinalized rats (n=6) which exhibited both weight supporting locomotion and stance, and also normal rats (n=8). Ground reaction forces in individual limbs, and the animals’ center of pressure were examined. In normal rats, both forelimbs and hindlimbs participated actively to control horizontal components of ground reaction forces. Rostral perturbations increased forelimb ground reaction forces, and caudal perturbations increased hindlimb ground reaction forces. Operate rats carried 60% body weight on the forelimbs and had a more rostral center of pressure placement. Normal rats pattern was to carry significantly more weight on the hindlimbs in quiet stance (~60%). Operate rats strategy of compensation for perturbations was entirely in forelimbs; as a result, the hind-limbs were largely isolated from the perturbation. Stiffness magnitude of the whole body was measured: its magnitude was hourglass shaped, with the principal axis oriented rostrocaudally. Operate rats were significantly less stiff; only 60-75% of normal rats’ stiffness. The injured rats adopt a stance strategy that isolates the hindlimbs from perturbation and may thus prevent hindlimb loadings. Such loadings could initiate reflex stepping, which we observed. This might activate lumbar pattern generators used in their locomotion. Adult spinalized rats never achieve independent hindlimb weight supported stance. The stance strategy of the P1 spinalized rats differed strongly from the behavior of intact rats and may be difficult for rats spinalized as adults to master. PMID:17287444

  8. Effects of dexmedetomidine on P2X4Rs, p38-MAPK and BDNF in spinal microglia in rats with spared nerve injury.

    PubMed

    Zhou, Tian-tian; Wu, Jing-ru; Chen, Zi-yang; Liu, Zhen-xiu; Miao, Bei

    2014-06-01

    Microglia in the spinal cord is evidenced to play a crucial role in neuropathic pain. Spinal P2X4 receptors (P2X4Rs), which are mainly expressed in microglia, have been investigated for their roles in neuropathic pain. Dexmedetomidine (DEX), a highly selective agonist of α2-adrenergic receptors, is clinically applied to sedation and analgesia. Despite the proposed mechanisms underlying DEX-induced analgesia, the possible interactions between DEX and P2X4Rs at a molecular level have not been elucidated. We designated the spared nerve injury (SNI) to establish the neuropathic pain model. Mechanical paw withdrawal threshold (MWT) was measured to evaluate the sensitivity of neuropathic pain in rats. MWT was significantly decreased in SNI rats versus control rats. Expressions of spinal P2X4Rs, phosphorylated p38-mitogen-activated protein kinase (p-p38-MAPK) and brain-derived neurotrophic factor (BDNF) were upregulated in SNI rats. Immunofluorescence assay indicated higher densities of microglia and P2X4Rs, which appeared yellow in colour, suggesting they were co-labelled. Intraperitoneal injections of DEX 40μg/kg for 14 consecutive days markedly reversed the SNI-induced decline of MWT; the activation of microglia was markedly inhibited; in addition, the protein expressions of P2X4Rs, p-p38-MAPK and BDNF were significantly downregulated. Thus, DEX could attenuate the neuropathic pain in SNI rats, of which the mechanism might be related to the down-expressed P2X4Rs, p-p38 and BDNF in microglia of spinal dorsal horn. PMID:24792496

  9. Electrophysiological Mapping of Rat Sensorimotor Lumbosacral Spinal Networks after Complete Paralysis

    PubMed Central

    Gad, Parag; Roy, Roland R.; Choe, Jaehoon; Zhong, Hui; Nandra, Mandheeraj Singh; Tai, Y.C.; Gerasimenko, Yury; Edgerton, V. Reggie

    2015-01-01

    Stimulation of the spinal cord has been shown to have great potential for improving function after motor deficits caused by injury or pathological conditions. Using a wide range of animal models, many studies have shown that stimulation applied to the neural networks intrinsic to the spinal cord can result in a dramatic improvement of motor ability, even allowing an animal to step and stand after a complete spinal cord transection. Clinical use of this technology, however, has been slow to develop due to the invasive nature of the implantation procedures and the difficulty of ascertaining specific sites of stimulation that would provide optimal amelioration of the motor deficits. Moreover, the development of tools available to control precise stimulation chronically via biocompatible electrodes has been limited. In this paper, we outline the use of a multisite electrode array in the spinal rat model to identify and stimulate specific sites of the spinal cord to produce discrete motor behaviors in spinal rats. The results demonstrate that spinal rats can stand and step when the spinal cord is stimulated tonically via electrodes located at specific sites on the spinal cord. The quality of stepping and standing was dependent on the location of the electrodes on the spinal cord, the specific stimulation parameters, and the orientation of the cathode and anode. The spinal motor evoked potentials (sMEP) in selected muscles during standing and stepping are shown to be critical tools to study selective activation of interneuronal circuits via responses of varying latencies. The present results provide further evidence that the assessment of functional networks in the background of behaviorally relevant functional states is likely to be a physiological tool of considerable importance in developing strategies to facilitate recovery of motor function after a number of neuromotor disorders. PMID:25890138

  10. Perfusion assessment in rat spinal cord tissue using photoplethysmography and laser Doppler flux measurements

    NASA Astrophysics Data System (ADS)

    Phillips, Justin P.; Cibert-Goton, Vincent; Langford, Richard M.; Shortland, Peter J.

    2013-03-01

    Animal models are widely used to investigate the pathological mechanisms of spinal cord injury (SCI), most commonly in rats. It is well known that compromised blood flow caused by mechanical disruption of the vasculature can produce irreversible damage and cell death in hypoperfused tissue regions and spinal cord tissue is particularly susceptible to such damage. A fiberoptic photoplethysmography (PPG) probe and instrumentation system were used to investigate the practical considerations of making measurements from rat spinal cord and to assess its suitability for use in SCI models. Experiments to assess the regional perfusion of exposed spinal cord in anesthetized adult rats using both PPG and laser Doppler flowmetry (LDF) were performed. It was found that signals could be obtained reliably from all subjects, although considerable intersite and intersubject variability was seen in the PPG signal amplitude compared to LDF. We present results from 30 measurements in five subjects, the two methods are compared, and practical application to SCI animal models is discussed.

  11. Transplantation of Neural Stem Cells Cultured in Alginate Scaffold for Spinal Cord Injury in Rats

    PubMed Central

    Sharafkhah, Ali; Koohi-Hosseinabadi, Omid; Semsar-Kazerooni, Maryam

    2016-01-01

    Study Design This study investigated the effects of transplantation of alginate encapsulated neural stem cells (NSCs) on spinal cord injury in Sprague-Dawley male rats. The neurological functions were assessed for 6 weeks after transplantation along with a histological study and measurement of caspase-3 levels. Purpose The aim of this study was to discover whether NSCs cultured in alginate transplantation improve recovery from spinal cord injury. Overview of Literature Spinal cord injury is one of the leading causes of disability and it has no effective treatment. Spinal cord injury can also cause sensory impairment. With an impetus on using stem cells therapy in various central nervous system settings, there is an interest in using stem cells for addressing spinal cord injury. Neural stem cell is one type of stem cells that is able to differentiate to all three neural lineages and it shows promise in spinal injury treatment. Furthermore, a number of studies have shown that culturing NSCs in three-dimensional (3D) scaffolds like alginate could enhance neural differentiation. Methods The NSCs were isolated from 14-day-old rat embryos. The isolated NSCs were cultured in growth media containing basic fibroblast growth factor and endothelial growth factor. The cells were characterized by differentiating to three neural lineages and they were cultured in an alginate scaffold. After 7 days the cells were encapsulated and transplanted in a rat model of spinal cord injury. Results Our data showed that culturing in an alginate 3D scaffold and transplantation of the NSCs could improve neurological outcome in a rat model of spinal cord injury. The inflammation scores and lesion sizes and also the activity of caspase-3 (for apoptosis evaluation) were less in encapsulated neural stem cell transplantation cases. Conclusions Transplantation of NSCs that were cultured in an alginate scaffold led to a better clinical and histological outcome for recovery from spinal cord injury in

  12. Coexistence of choline acetyltransferase and GABA in axon terminals in the dorsal cap of the rat inferior olive.

    PubMed

    Caffé, A R; Hawkins, R K; De Zeeuw, C I

    1996-06-10

    The dorsal cap of Kooy of the inferior olive (DC) is involved in compensatory eye movements. The rat DC receives a prominent input from the nucleus prepositus hypoglossi (NPH); part of these axon terminals are immunoreactive for choline acetyltransferase (ChAT) and part of them are GABAergic. In the present study we investigated the fine distribution of cholinergic terminals in the rat DC, and the possible coexistence of ChAT and GABA. ChAT-positive terminals were observed throughout the entire neuropil of the rat DC contacting both extraglomerular and intraglomerular dendrites. Twenty nine percent of these terminals also contained GABA. The ChAT/GABA double-labelled terminals showed the same morphological characteristics as terminals traced from the NPH. The present data demonstrate colocalization of ChAT and GABA in axon terminals of the rat DC and strongly suggest that neurons in the NPH are the source of these profiles. PMID:8816268

  13. Distinct antinociceptive actions mediated by different opioid receptors in the region of lamina I and laminae III-V of the dorsal horn of the rat.

    PubMed Central

    Hope, P. J.; Fleetwood-Walker, S. M.; Mitchell, R.

    1990-01-01

    1. In view of the presence of mu, delta and kappa opioid receptors in the spinal dorsal horn and their apparent involvement in behavioural analgesia, the present experiments addressed the action of selective agonists ionophoresed in the vicinity of rat dorsal horn neurones which were located either in lamina I or in laminae III-V. 2. In laminae III-V, kappa agonists (U50488H and dynorphin A) caused a selective inhibition of the nociceptive responses of multireceptive cells, whilst mu and delta agonists [( D-Ala2, MePhe4, Gly-ol]enkephalin and [D-Pen2, D-Pen5]enkephalin respectively) failed to alter either the spontaneous activity or the response to noxious and innocuous cutaneous stimuli and to D,L-homocysteic acid or glutamate. Nocispecific neurones were encountered too rarely in laminae III-V to study their properties. 3. In lamina I, agonists had no effects on either nocispecific or multireceptive neurones. In contrast, the mu agonist [D-Ala2, MePhe4, Gly-ol]enkephalin consistently inhibited nociceptive responses of both multireceptive and nocispecific lamina I cells. The delta agonist [D-Pen2, D-Pen5]enkephalin consistently caused selective inhibition of the nociceptive responses of multireceptive cells but had a mixed profile of action on nocispecific cells. 4. These results suggest that mu, delta and kappa opioid receptors mediate different antinociceptive actions in both laminae III-V and lamina I. The study reveals a distinct physiological role for delta receptors in modulating nociceptive inputs to lamina I neurones. In contrast to mu and kappa receptor actions, delta receptors heterogeneously influence subpopulations of neurones. PMID:2175238

  14. Efficient retrograde transport of adeno-associated virus type 8 to spinal cord and dorsal root ganglion after vector delivery in muscle.

    PubMed

    Zheng, Hui; Qiao, Chunping; Wang, Chi-Hsien; Li, Juan; Li, Jianbin; Yuan, Zhenhua; Zhang, Cheng; Xiao, Xiao

    2010-01-01

    The peripheral nervous system (PNS), including peripheral nerves and dorsal root ganglion (DRG), is involved in numerous neurological disorders, such as peripheral neuropathies (diabetic neuropathy, chronic pain, etc.) and demyelination diseases (multiple sclerosis, congenital muscular dystrophy, Charcot-Marie-Tooth disease, etc.). Effective clinical interventions for those diseases are very limited. Gene therapy represents a novel therapeutic strategy for the PNS diseases, especially with simply and minimally invasive delivery methods. Previously, we have shown that adeno-associated virus type 8 (AAV8) can efficiently transduce muscles body wide by a simple intraperitoneal injection in neonatal mice. In this study, we investigated the capacity of AAV8 in transducing PNS in neonatal mice by intraperitoneal injection and also in adult mice by intramuscular injection. Efficient and long-term gene transfer was found in the white matter of the spinal cord, DRG neurons, and peripheral nerves in both groups, treated either as neonates or as adults, particularly neonates. In the adult mice injected with AAV8 in tibialis anterior and gastrocnemius muscles in one of the hind legs, more neurons were transduced in the lower part of the spinal cord than in the upper part; the DRG neurons were transduced more on the vector-injected side than in the contralateral uninjected side. Few cells in the gray matter of the spinal cord were transduced regardless of the delivery methods and age of the mice. These results support the mechanism of vector retrograde transport and suggest that AAV8 crosses blood-nerve barrier poorly. Our finding should have important implications in gene therapy for peripheral neurological disorders. PMID:19719401

  15. Effects of sciatic nerve transection on glucose uptake in the presence and absence of lactate in the frog dorsal root ganglia and spinal cord.

    PubMed

    Rigon, F; Horst, A; Kucharski, L C; Silva, R S M; Faccioni-Heuser, M C; Partata, W A

    2014-08-01

    Frogs have been used as an alternative model to study pain mechanisms because the simplicity of their nervous tissue and the phylogenetic aspect of this question. One of these models is the sciatic nerve transection (SNT), which mimics the clinical symptoms of "phantom limb", a condition that arises in humans after amputation or transverse spinal lesions. In mammals, the SNT increases glucose metabolism in the central nervous system, and the lactate generated appears to serve as an energy source for nerve cells. An answerable question is whether there is elevated glucose uptake in the dorsal root ganglia (DRG) after peripheral axotomy. As glucose is the major energy substrate for frog nervous tissue, and these animals accumulate lactic acid under some conditions, bullfrogs Lithobates catesbeianus were used to demonstrate the effect of SNT on DRG and spinal cord 1-[14C] 2-deoxy-D-glucose (14C-2-DG) uptake in the presence and absence of lactate. We also investigated the effect of this condition on the formation of 14CO2 from 14C-glucose and 14C-L-lactate, and plasmatic glucose and lactate levels. The 3-O-[14C] methyl-D-glucose (14C-3-OMG) uptake was used to demonstrate the steady-state tissue/medium glucose distribution ratio under these conditions. Three days after SNT, 14C-2-DG uptake increased, but 14C-3-OMG uptake remained steady. The increase in 14C-2-DG uptake was lower when lactate was added to the incubation medium. No change was found in glucose and lactate oxidation after SNT, but lactate and glucose levels in the blood were reduced. Thus, our results showed that SNT increased the glucose metabolism in the frog DRG and spinal cord. The effect of lactate on this uptake suggests that glucose is used in glycolytic pathways after SNT. PMID:25627385

  16. Nicotine increases GABAergic input on rat dorsal raphe serotonergic neurons through alpha7 nicotinic acetylcholine receptor.

    PubMed

    Hernández-Vázquez, F; Chavarría, K; Garduño, J; Hernández-López, S; Mihailescu, S P

    2014-12-15

    The dorsal raphe nucleus (DRN) contains large populations of serotonergic (5-HT) neurons. This nucleus receives GABAergic inhibitory afferents from many brain areas and from DRN interneurons. Both GABAergic and 5-HT DRN neurons express functional nicotinic acetylcholine receptors (nAChRs). Previous studies have demonstrated that nicotine increases 5-HT release and 5-HT DRN neuron discharge rate by stimulating postsynaptic nAChRs and by increasing glutamate and norepinephrine release inside DRN. However, the influence of nicotine on the GABAergic input to 5-HT DRN neurons was poorly investigated. Therefore, the aim of this work was to determine the effect of nicotine on GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs) of 5-HT DRN neurons and the subtype of nAChR(s) involved in this response. Experiments were performed in coronal slices obtained from young Wistar rats. GABAergic sIPSCs were recorded from post hoc-identified 5-HT DRN neurons with the whole cell voltage patch-clamp technique. Administration of nicotine (1 μM) increased sIPSC frequency in 72% of identified 5-HT DRN neurons. This effect was not reproduced by the α4β2 nAChR agonist RJR-2403 and was not influenced by TTX (1 μM). It was mimicked by the selective agonist for α7 nAChR, PNU-282987, and exacerbated by the positive allosteric modulator of the same receptor, PNU-120596. The nicotine-induced increase in sIPSC frequency was independent on voltage-gated calcium channels and dependent on Ca(2+)-induced Ca(2+) release (CICR). These results demonstrate that nicotine increases the GABAergic input to most 5-HT DRN neurons, by activating α7 nAChRs and producing CICR in DRN GABAergic terminals. PMID:25231613

  17. Amitriptyline Activates TrkA to Aid Neuronal Growth and Attenuate Anesthesia-Induced Neurodegeneration in Rat Dorsal Root Ganglion Neurons.

    PubMed

    Zheng, Xiaochun; Chen, Feng; Zheng, Ting; Huang, Fengyi; Chen, Jianghu; Tu, Wenshao

    2016-05-01

    Tricyclic antidepressant amitriptyline (AM) has been shown to exert neurotrophic activity on neurons. We thus explored whether AM may aid the neuronal development and protect anesthesia-induced neuro-injury in young spinal cord dorsal root ganglion (DRG) neurons.The DRG explants were prepared from 1-day-old rats. The effect of AM on aiding DRG neural development was examined by immunohistochemistry at dose-dependent manner. AM-induced changes in gene and protein expressions, and also phosphorylation states of tyrosine kinases receptor A (TrkA) and B (TrkB) in DRG, were examined by quantitative real-time polymerase chain reaction and western blot. The effect of AM on attenuating lidocaine-induced DRG neurodegeneration was examined by immunohistochemistry, and small interfering RNA (siRNA)-mediated TrkA/B down-regulation.Amitriptyline stimulated DRG neuronal development in dose-dependent manner, but exerted toxic effect at concentrations higher than 10 M. AM activated TrkA in DRG through phosphorylation, whereas it had little effect on TrkB-signaling pathway. AM reduced lidocaine-induced DRG neurodegeneration by regenerating neurites and growth cones. Moreover, the neuroprotection of AM on lidocaine-injured neurodegeneration was blocked by siRNA-mediated TrkA down-regulation, but not by TrkB down-regulation.Amitriptyline facilitated neuronal development and had protective effect on lidocaine-induced neurodegeneration, very likely through the activation of TrkA-signaling pathway in DRG. PMID:27149473

  18. Amitriptyline Activates TrkA to Aid Neuronal Growth and Attenuate Anesthesia-Induced Neurodegeneration in Rat Dorsal Root Ganglion Neurons

    PubMed Central

    Zheng, Xiaochun; Chen, Feng; Zheng, Ting; Huang, Fengyi; Chen, Jianghu; Tu, Wenshao

    2016-01-01

    Abstract Tricyclic antidepressant amitriptyline (AM) has been shown to exert neurotrophic activity on neurons. We thus explored whether AM may aid the neuronal development and protect anesthesia-induced neuro-injury in young spinal cord dorsal root ganglion (DRG) neurons. The DRG explants were prepared from 1-day-old rats. The effect of AM on aiding DRG neural development was examined by immunohistochemistry at dose-dependent manner. AM-induced changes in gene and protein expressions, and also phosphorylation states of tyrosine kinases receptor A (TrkA) and B (TrkB) in DRG, were examined by quantitative real-time polymerase chain reaction and western blot. The effect of AM on attenuating lidocaine-induced DRG neurodegeneration was examined by immunohistochemistry, and small interfering RNA (siRNA)-mediated TrkA/B down-regulation. Amitriptyline stimulated DRG neuronal development in dose-dependent manner, but exerted toxic effect at concentrations higher than 10 M. AM activated TrkA in DRG through phosphorylation, whereas it had little effect on TrkB-signaling pathway. AM reduced lidocaine-induced DRG neurodegeneration by regenerating neurites and growth cones. Moreover, the neuroprotection of AM on lidocaine-injured neurodegeneration was blocked by siRNA-mediated TrkA down-regulation, but not by TrkB down-regulation. Amitriptyline facilitated neuronal development and had protective effect on lidocaine-induced neurodegeneration, very likely through the activation of TrkA-signaling pathway in DRG. PMID:27149473

  19. Genomewide Analysis of Rat Periaqueductal Gray-Dorsal Horn Reveals Time-, Region- and Frequency-Specific mRNA Expression Changes in Response to Electroacupuncture Stimulation

    PubMed Central

    Wang, Ke; Xiang, Xiao-Hui; Qiao, Nan; Qi, Jun-Yi; Lin, Li-Bo; Zhang, Rong; Shou, Xiao-jing; Ping, Xing-Jie; Han, Ji-Sheng; Han, Jing-Dong; Zhao, Guo-Ping; Cui, Cai-Lian

    2014-01-01

    Electroacupuncture (EA) has been widely applied for illness prevention, treatment or rehabilitation in the clinic, especially for pain management. However, the molecular events that induce these changes remain largely uncharacterized. The periaqueductal gray (PAG) and the spinal dorsal horn (DH) have been verified as two critical regions in the response to EA stimulation in EA analgesia. In this study, a genetic screen was conducted to delineate the gene expression profile in the PAG-DH regions of rats to explore the molecular events of the analgesic effect induced by low-frequency (2-Hz) and high-frequency (100-Hz) EAs. Microarray analysis at two different time points after EA stimulation revealed time-, region- and frequency-specific gene expression changes. These expression differences suggested that modulation of neural-immune interaction in the central nervous system played an important role during EA analgesia. Furthermore, low-frequency EA could regulate gene expression to a greater degree than high-frequency EA. Altogether, the present study offers, for the first time, a characterized transcriptional response pattern in the PAG-DH regions followed by EA stimulation and, thus, provides a solid experimental framework for future in-depth analysis of the mechanisms underlying EA-induced effects. PMID:25346229

  20. MicroRNA-mediated GABA Aα-1 receptor subunit down-regulation in adult spinal cord following neonatal cystitis-induced chronic visceral pain in rats.

    PubMed

    Sengupta, Jyoti N; Pochiraju, Soumya; Pochiraju, Soumiya; Kannampalli, Pradeep; Bruckert, Mitchell; Addya, Sankar; Yadav, Priyanka; Miranda, Adrian; Shaker, Reza; Banerjee, Banani

    2013-01-01

    The nociceptive transmission under pathological chronic pain conditions involves transcriptional and/or translational alteration in spinal neurotransmitters, receptor expressions, and modification of neuronal functions. Studies indicate the involvement of microRNA (miRNA) - mediated transcriptional deregulation in the pathophysiology of acute and chronic pain. In the present study, we tested the hypothesis that long-term cross-organ colonic hypersensitivity in neonatal zymosan-induced cystitis is due to miRNA-mediated posttranscriptional suppression of the developing spinal GABAergic system. Cystitis was produced by intravesicular injection of zymosan (1% in saline) into the bladder during postnatal (P) days P14 through P16 and spinal dorsal horns (L6-S1) were collected either on P60 (unchallenged groups) or on P30 after a zymosan re-challenge on P29 (re-challenged groups). miRNA arrays and real-time reverse transcription-polymerase chain reaction (RT-PCR) revealed significant, but differential, up-regulation of mature miR-181a in the L6-S1 spinal dorsal horns from zymosan-treated rats compared with saline-treated controls in both the unchallenged and re-challenged groups. The target gene analysis demonstrated multiple complementary binding sites in miR-181a for GABA(A) receptor subunit GABA(Aα-1) gene with a miRSVR score of -1.83. An increase in miR-181a concomitantly resulted in significant down-regulation of GABA(Aα-1) receptor subunit gene and protein expression in adult spinal cords from rats with neonatal cystitis. Intrathecal administration of the GABA(A) receptor agonist muscimol failed to attenuate the viscero-motor response (VMR) to colon distension in rats with neonatal cystitis, whereas in adult zymosan-treated rats the drug produced significant decrease in VMR. These results support an integral role for miRNA-mediated transcriptional deregulation of the GABAergic system in neonatal cystitis-induced chronic pelvic pain. PMID:23273104

  1. Involvement of subtype 1 metabotropic glutamate receptors in apoptosis and caspase-7 over-expression in spinal cord of neuropathic rats

    PubMed Central

    Siniscalco, Dario; Giordano, Catia; Fuccio, Carlo; Luongo, Livio; Ferraraccio, Franca; Rossi, Francesca; de Novellis, Vito; Roth, Kevin A.; Maione, Sabatino

    2008-01-01

    The effect of the non-selective, 1-aminoindan-1,5-dicarboxylic acid (AIDA), and selective (3,4-dihydro-2H-pyrano[2,3-b]quinolin-7-yl)-(cis-4- methoxycyclohexyl) methanone (JNJ16259685), metabotropic glutamate subtype 1 (mGlu1) receptor antagonists, on rat sciatic nerve chronic constrictive injury (CCI)- induced hyperalgesia, allodynia, spinal dorsal horn apoptosis, and gliosis was examined at 3 and 7 days post-injury. RT-PCR analysis showed increased expression of bax, apoptotic protease-activating factor-1 (apaf-1), nestin, GFAP, and caspase-7 mRNA in the dorsal horn spinal cord by 3 days post-CCI. At 7 days post-CCI, only over-expression of bcl-2, nestin and GFAP mRNA was observed. Administration of AIDA reduced thermal hyperalgesia and mechanical allodynia at 3 and 7 days post-CCI; administration of JNJ16259685 reduced thermal hyperalgesia at 3 and 7 days post-CCI, but not mechanical allodynia. AIDA decreased the mRNA levels of bax, apaf-1, GFAP and caspase-7 genes. JNJ16259685 increased the mRNA levels of bcl- 2 and GFAP gene, and decreased APAF-1 and caspases-7 genes. Inhibiting mGlu1 receptors also reduced TUNEL-positive profiles and immunohistochemical reactivity for caspase-7. We report here that despite inhibiting CCI-induced over-expression of pro-apoptotic genes in the spinal cord dorsal horn, the selective mGlu1 receptor antagonist JNJ16259685 exerted only a slight and transient allodynic effect. Moreover, JNJ16259685, but not the non-selective AIDA, increased astrogliosis which may account for its decreased analgesic efficacy. This study provides evidence that the contemporary and partial blockade of group I and likely ionotropic glutamate receptors may be a more suitable therapy than selective blockade of mGlu1 subtype receptors condition to decrease neuropathic pain symptoms. PMID:18325779

  2. Docosahexaenoic acid pretreatment confers protection and functional improvements after acute spinal cord injury in adult rats.

    PubMed

    Figueroa, Johnny D; Cordero, Kathia; Baldeosingh, Keisha; Torrado, Aranza I; Walker, Robert L; Miranda, Jorge D; Leon, Marino De

    2012-02-10

    Currently, few interventions have been shown to successfully limit the progression of secondary damage events associated with the acute phase of spinal cord injury (SCI). Docosahexaenoic acid (DHA, C22:6 n-3) is neuroprotective when administered following SCI, but its potential as a pretreatment modality has not been addressed. This study used a novel DHA pretreatment experimental paradigm that targets acute cellular and molecular events during the first week after SCI in rats. We found that DHA pretreatment reduced functional deficits during the acute phase of injury, as shown by significant improvements in Basso-Beattie-Bresnahan (BBB) locomotor scores, and the detection of transcranial magnetic motor evoked potentials (tcMMEPs) compared to vehicle-pretreated animals. We demonstrated that, at 7 days post-injury, DHA pretreatment significantly increased the percentage of white matter sparing, and resulted in axonal preservation, compared to the vehicle injections. We found a significant increase in the survival of NG2+, APC+, and NeuN+ cells in the ventrolateral funiculus (VLF), dorsal corticospinal tract (dCST), and ventral horns, respectively. Interestingly, these DHA protective effects were observed despite the lack of inhibition of inflammatory markers for monocytes/macrophages and astrocytes, ED1/OX42 and GFAP, respectively. DHA pretreatment induced levels of Akt and cyclic AMP responsive element binding protein (CREB) mRNA and protein. This study shows for the first time that DHA pretreatment ameliorates functional deficits, and increases tissue sparing and precursor cell survival. Further, our data suggest that DHA-mediated activation of pro-survival/anti-apoptotic pathways may be independent of its anti-inflammatory effects. PMID:21970623

  3. Docosahexaenoic Acid Pretreatment Confers Protection and Functional Improvements after Acute Spinal Cord Injury in Adult Rats

    PubMed Central

    Figueroa, Johnny D.; Cordero, Kathia; Baldeosingh, Keisha; Torrado, Aranza I.; Walker, Robert L.; Miranda, Jorge D.

    2012-01-01

    Abstract Currently, few interventions have been shown to successfully limit the progression of secondary damage events associated with the acute phase of spinal cord injury (SCI). Docosahexaenoic acid (DHA, C22:6 n-3) is neuroprotective when administered following SCI, but its potential as a pretreatment modality has not been addressed. This study used a novel DHA pretreatment experimental paradigm that targets acute cellular and molecular events during the first week after SCI in rats. We found that DHA pretreatment reduced functional deficits during the acute phase of injury, as shown by significant improvements in Basso-Beattie-Bresnahan (BBB) locomotor scores, and the detection of transcranial magnetic motor evoked potentials (tcMMEPs) compared to vehicle-pretreated animals. We demonstrated that, at 7 days post-injury, DHA pretreatment significantly increased the percentage of white matter sparing, and resulted in axonal preservation, compared to the vehicle injections. We found a significant increase in the survival of NG2+, APC+, and NeuN+ cells in the ventrolateral funiculus (VLF), dorsal corticospinal tract (dCST), and ventral horns, respectively. Interestingly, these DHA protective effects were observed despite the lack of inhibition of inflammatory markers for monocytes/macrophages and astrocytes, ED1/OX42 and GFAP, respectively. DHA pretreatment induced levels of Akt and cyclic AMP responsive element binding protein (CREB) mRNA and protein. This study shows for the first time that DHA pretreatment ameliorates functional deficits, and increases tissue sparing and precursor cell survival. Further, our data suggest that DHA-mediated activation of pro-survival/anti-apoptotic pathways may be independent of its anti-inflammatory effects. PMID:21970623

  4. Antagonism of mGlu receptors and potentiation of EPSCs at rat spinal motoneurones in vitro.

    PubMed

    Cao, C Q; Tse, H W; Jane, D E; Evans, R H; Headley, P M

    1997-03-01

    The patch-clamp technique has been used to record synaptic responses, elicited by electrical stimulation of dorsal roots, in 28 single motoneurones of in vitro spinal cord preparations from neonate (P5 to P8) rats. The effects of (RS)-alpha-methyl-4-phosphonophenylglycine (MPPG) (200 microM), a potent antagonist at L-2-amino-4-phosphonobutanoate (AP4)-sensitive receptors, and (RS)-alpha-methyl-4-carboxyphenylglycine (MCPG) (500 microM), which is a less selective antagonist of mGluRs, were tested on EPSCs alone and as antagonists of AP4-induced depression of EPSCs. The EC50 for depression of EPSCs by AP4 (1.16 +/- 0.12 microM, n = 8) was increased to 18.9 +/- 0.7 microM (n = 6) by MPPG. MCPG (500 microM) had no significant effect on the depressant potency of AP4. Under control conditions, EPSCs had mean peak amplitudes of 983 pA +/- 64 SEM and mean charge transferred of 306 +/- 37 pC (n = 28). These values were increased significantly (p < 0.05) to 1168 +/- 68 pA and 363 +/- 39 pC by MPPG (n = 6), and 1150 +/- 54 pA and 358 +/- 33 pC (n = 6) by MCPG. There was no significant difference between the enhancement of the initial peak of the EPSCs (mean latency from stimulus artifact 5.9 +/- 0.3 ms) and later components, suggesting mGluRs to be present on primary afferent terminals presynaptic to motoneurones as well as in pathways via interneurones. These results are consistent with the presence of at least two types of presynaptic mGluR that modulate release of glutamate in segmental pathways convergent onto motoneurones. These receptors appear to be activated by interstitial glutamate tonically present in the present preparations. PMID:9175609

  5. Transplantation of choroid plexus epithelial cells into contusion-injured spinal cord of rats

    PubMed Central

    Kanekiyo, Kenji; Nakano, Norihiko; Noda, Toru; Yamada, Yoshihiro; Suzuki, Yoshihisa; Ohta, Masayoshi; Yokota, Atsushi; Fukushima, Masanori; Ide, Chizuka

    2016-01-01

    Purpose: The effect of the transplantation of choroid plexus epithelial cells (CPECs) on locomotor improvement and tissue repair including axonal extension in spinal cord lesions was examined in rats with spinal cord injury (SCI). Methods: CPECs were cultured from the choroid plexus of green fluorescent protein (GFP)-transgenic rats, and transplanted directly into the contusion-injured spinal cord lesions of rats of the same strain. Locomotor behaviors were evaluated based on BBB scores every week after transplantation until 4 weeks after transplantation. Histological and immunohistochemical examinations were performed at 2 days, and every week until 5 weeks after transplantation. Results: Locomotor behaviors evaluated by the BBB score were significantly improved in cell-transplanted rats. Numerous axons grew, with occasional interactions with CPECs, through the astrocyte-devoid areas. These axons exhibited structural characteristics of peripheral nerves. GAP-43-positive axons were found at the border of the lesion 2 days after transplantation. Cavity formation was more reduced in cell-transplanted than control spinal cords. CPECs were found within the spinal cord lesion, and sometimes in association with astrocytes at the border of the lesion until 2 weeks after transplantation. Conclusion: The transplantation of CPECs enhanced locomotor improvement and tissue recovery, including axonal regeneration, in rats with SCI. PMID:26923614

  6. Longitudinal Evaluation of Residual Cortical and Subcortical Motor Evoked Potentials in Spinal Cord Injured Rats.

    PubMed

    Redondo-Castro, Elena; Navarro, Xavier; García-Alías, Guillermo

    2016-05-15

    We have applied transcranial electrical stimulation to rats with spinal cord injury and selectively tested the motor evoked potentials (MEPs) conveyed by descending motor pathways with cortical and subcortical origin. MEPs were elicited by electrical stimulation to the brain and recorded on the tibialis anterior muscles. Stimulation parameters were characterized and changes in MEP responses tested in uninjured rats, in rats with mild or moderate contusion, and in animals with complete transection of the spinal cord. All injuries were located at the T8 vertebral level. Two peaks, termed N1 and N2, were obtained when changing from single pulse stimulation to trains of 9 pulses at 9 Hz. Selective injuries to the brain or spinal cord funiculi evidenced the subcortical origin of N1 and the cortical origin of N2. Animals with mild contusion showed small behavioral deficits and abolished N1 but maintained small amplitude N2 MEPs. Substantial motor deficits developed in rats with moderate contusion, and these rats had completely eliminated N1 and N2 MEPs. Animals with complete cord transection had abolished N1 and N2 and showed severe impairment of locomotion. The results indicate the reliability of MEP testing to longitudinally evaluate over time the degree of impairment of cortical and subcortical spinal pathways after spinal cord injuries of different severity. PMID:26560177

  7. Evaluation of spinal toxicity and long-term spinal reflex function following intrathecal levobupivacaine in the neonatal rat

    PubMed Central

    Hamurtekin, Emre; Fitzsimmons, Bethany L.; Shubayev, Veronica I.; Grafe, Marjorie R.; Deumens, Ronald; Yaksh, Tony L.; Walker, Suellen M.

    2013-01-01

    Background Neuraxial anesthesia is utilized in children of all ages. Local anesthetics produce dose-dependent toxicity in certain adult models, but the developing spinal cord may also be susceptible to drug-induced apoptosis. In postnatal rodents, we examined effects of intrathecal levobupivacaine on neuropathology and long-term sensorimotor outcomes. Methods Postnatal day 3 (P3) or P7 rat pups received intrathecal levobupivacaine 2.5mg/kg (0.5%) or saline. Mechanical withdrawal thresholds and motor block were assessed. Spinal cord tissue analysis included: apoptosis counts (activated-caspase-3, Fluoro-Jade C) at 24 h; glial reactivity at 7 days; and histopathology in cord and cauda equina at 24 h and 7 days. Long-term spinal function in young adults (P35) was assessed by hindlimb withdrawal thresholds, electromyography responses to suprathreshold stimuli, and gait analysis. Results Intrathecal levobupivacaine produced spinal anesthesia at P3 and P7. No increase in apoptosis or histopathological change was seen in the cord or cauda equina. In the P3 saline group, activated-caspase-3 (mean±SEM per lumbar cord section 6.1±0.3) and Fluoro-Jade C (12.1±1.2) counts were higher than at P7, but were not altered by levobupivacaine (P=0.62 and P=0.11, two-tailed Mann-Whitney test). At P35, mechanical withdrawal thresholds, thermal withdrawal latency and electromyographic reflex responses did not differ across P3 or P7 levobupivacaine or saline groups (one way ANOVA with Bonferroni comparisons). Intrathecal bupivacaine at P3 did not alter gait. Conclusion Single dose intrathecal levobupivacaine 0.5% did not increase apoptosis or produce spinal toxicity in neonatal rat pups. This study provides preclinical safety data relevant to neonatal use of neuraxial local anesthesia. PMID:23514721

  8. Repetitive Treatment with Diluted Bee Venom Attenuates the Induction of Below-Level Neuropathic Pain Behaviors in a Rat Spinal Cord Injury Model.

    PubMed

    Kang, Suk-Yun; Roh, Dae-Hyun; Choi, Jung-Wan; Ryu, Yeonhee; Lee, Jang-Hern

    2015-07-01

    The administration of diluted bee venom (DBV) into an acupuncture point has been utilized traditionally in Eastern medicine to treat chronic pain. We demonstrated previously that DBV has a potent anti-nociceptive efficacy in several rodent pain models. The present study was designed to examine the potential anti-nociceptive effect of repetitive DBV treatment in the development of below-level neuropathic pain in spinal cord injury (SCI) rats. DBV was applied into the Joksamli acupoint during the induction and maintenance phase following thoracic 13 (T13) spinal hemisection. We examined the effect of repetitive DBV stimulation on SCI-induced bilateral pain behaviors, glia expression and motor function recovery. Repetitive DBV stimulation during the induction period, but not the maintenance, suppressed pain behavior in the ipsilateral hind paw. Moreover, SCI-induced increase in spinal glia expression was also suppressed by repetitive DBV treatment in the ipsilateral dorsal spinal cord. Finally, DBV injection facilitated motor function recovery as indicated by the Basso-Beattie-Bresnahan rating score. These results indicate that the repetitive application of DBV during the induction phase not only decreased neuropathic pain behavior and glia expression, but also enhanced locomotor functional recovery after SCI. This study suggests that DBV acupuncture can be a potential clinical therapy for SCI management. PMID:26184310

  9. Expressions of caspase-3, Tunel, and Hsp72 immunoreactivities in cultured spinal cord neurons of rat after exposure to glutamate, nitric oxide, or peroxynitrite.

    PubMed

    Manabe, Y; Wang, J; Warita, H; Shiro, Y; Abe, K

    2001-07-01

    Although excitotoxic and oxidative stress play important roles in spinal neuron death, the exact mechanisms are not fully understood. We examined cell damage of primary culture of 11 day-old rat spinal cord by addition of glutamate, nitric oxice (NO) or peroxynitrite (PN) with detection of caspase-3, terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL) or 72 kDa heat shock protein (HSP72). With addition of glutamate, NOC18 (a slow NO releaser) or PN, immunoreactivity for caspase-3 became stronger in the cytoplasm of large motor neurons in the ventral horn at 6 to 24 hr. TUNEL positive nuclei were found in spinal large motor neurons from 24 h and the positive cell proportion greatly increased at 48 h in contrast to the vehicle. On the other hand, the immunoreactivity of HSP72 in the ventral horn was already positive at 0 h, and gradually decreased in the course of time with glutamate, NOC18 or PN than vehicle treatment. In the dorsal horn, the proportion of caspase-3 positive small neurons greatly increased at 6 to 48 h after addition of glutamate. The present results suggest that both excitotoxic and oxidative stress play important roles in the apoptotic pathway in cultured spinal neurons. PMID:15111253

  10. Repetitive Treatment with Diluted Bee Venom Attenuates the Induction of Below-Level Neuropathic Pain Behaviors in a Rat Spinal Cord Injury Model

    PubMed Central

    Kang, Suk-Yun; Roh, Dae-Hyun; Choi, Jung-Wan; Ryu, Yeonhee; Lee, Jang-Hern

    2015-01-01

    The administration of diluted bee venom (DBV) into an acupuncture point has been utilized traditionally in Eastern medicine to treat chronic pain. We demonstrated previously that DBV has a potent anti-nociceptive efficacy in several rodent pain models. The present study was designed to examine the potential anti-nociceptive effect of repetitive DBV treatment in the development of below-level neuropathic pain in spinal cord injury (SCI) rats. DBV was applied into the Joksamli acupoint during the induction and maintenance phase following thoracic 13 (T13) spinal hemisection. We examined the effect of repetitive DBV stimulation on SCI-induced bilateral pain behaviors, glia expression and motor function recovery. Repetitive DBV stimulation during the induction period, but not the maintenance, suppressed pain behavior in the ipsilateral hind paw. Moreover, SCI-induced increase in spinal glia expression was also suppressed by repetitive DBV treatment in the ipsilateral dorsal spinal cord. Finally, DBV injection facilitated motor function recovery as indicated by the Basso–Beattie–Bresnahan rating score. These results indicate that the repetitive application of DBV during the induction phase not only decreased neuropathic pain behavior and glia expression, but also enhanced locomotor functional recovery after SCI. This study suggests that DBV acupuncture can be a potential clinical therapy for SCI management. PMID:26184310

  11. Anatomical correlates of recovery in single pellet reaching in spinal cord injured rats.

    PubMed

    Hurd, C; Weishaupt, N; Fouad, K

    2013-09-01

    Modeling spinal cord injury (SCI) in animals is challenging because an appropriate combination of lesion location, lesion severity and behavioral testing is essential to analyze recovery of motor function. For particular tests such as single pellet reaching, the contribution of individual descending tracts to recovery has been investigated using specific tract ablation or graded lesions. However, it has not been established whether single pellet reaching is sufficiently sensitive for assessing the efficacy of treatments for cervical SCI (e.g., one of the currently most successful treatment approaches: rehabilitative training). To address this issue, we trained adult rats in single pellet reaching before and after a cervical (C4) spinal lesion. Animals with lesions of increasing severity were grouped into categories based on damage to anatomical structures such as the corticospinal tract (CST) and the rubrospinal tract (RST), two descending motor tracts that have been implicated in fine motor control of the forelimb. We related lesion extent to spontaneous recovery and plasticity-promoting post injury training and found that reaching performance was not correlated with lesion size or the extent of CST or RST injury. Interestingly, the dorsolateral quadrant (DLQ) lesion category, in which the unilateral dorsal CST and most of the unilateral RST are lesioned, was the only category that showed a clear effect of plasticity-promoting treatment (i.e., training), indicating its usefulness as a lesion model for this testing paradigm. The DLQ lesion likely strikes a balance between tissue sparing and functional impairment and is, therefore, best suited to maximize the potential to observe treatment effects of plasticity-promoting treatments using single pellet reaching. Because of the specific lesion size that is necessary to observe treatment effects, the single pellet skilled reaching task can be considered a stringent behavioral test and therefore may be useful for

  12. Persistent c-fos expression and NADPH-d reactivity in the medulla and the lumbar spinal cord in rat with short-term peripheral anosmia.

    PubMed

    Kalueff, A V; Maisky, V A; Pilyavskii, A I; Makarchuk, N E

    2001-03-30

    Here we examine hypothesis that short-term peripheral ZnSO(4)-induced anosmia can produce effects on c-fos expression within spinal cord and caudal medulla in male Wistar rats (n=4). Fos-like-immunoreactive cells revealed by avidin-biotin-peroxidase method show a significant bilateral increase in the nucleus proprius (layers 3 and 4) and medial part of layers 5 and 6. In substantia gelatinosa (layer 2(i)) and area 10 Fos-positive neurons were intermixed together with nicotin-amide adenine dineucleotide phosphate-diaphorase (NADPH-d)-reactive cells. Short-term anosmia enhanced c-fos expression in ventral horn (layers 7 and 8), ventrolateral segment and dorsal part of the spinal trigeminal nuclei. In anosmic rats varicose fibres and numerous NADPH-d-stained neurons were present in the gelatinous layer of the spinal trigeminal nucleus caudalis, and a separate population of Fos-positive cells was detected within this layer. Nucleus tractus solitaris also contained a few NADPH-d-reactive, medium sized neurons intermixed with Fos-immunoreactive cells. PMID:11248440

  13. Coapplication of noisy patterned electrical stimuli and NMDA plus serotonin facilitates fictive locomotion in the rat spinal cord.

    PubMed

    Dose, Francesco; Taccola, Giuliano

    2012-12-01

    A new stimulating protocol [fictive locomotion-induced stimulation (FListim)], consisting of intrinsically variable weak waveforms applied to a single dorsal root is very effective (though not optimal as it eventually wanes away) in activating the locomotor program of the isolated rat spinal cord. The present study explored whether combination of FListim with low doses of pharmacological agents that raise network excitability might further improve the functional outcome, using this in vitro model. FListim was applied together with N-methyl-d-aspartate (NMDA) + serotonin, while fictive locomotion (FL) was electrophysiologically recorded from lumbar ventral roots. Superimposing FListim on FL evoked by these neurochemicals persistently accelerated locomotor-like cycles to a set periodicity and modulated cycle amplitude depending on FListim rate. Trains of stereotyped rectangular pulses failed to replicate this phenomenon. The GABA(B) agonist baclofen dose dependently inhibited, in a reversible fashion, FL evoked by either FListim or square pulses. Sustained episodes of FL emerged when FListim was delivered, at an intensity subthreshold for FL, in conjunction with subthreshold pharmacological stimulation. Such an effect was, however, not found when high potassium solution instead of NMDA + serotonin was used. These results suggest that the combined action of subthreshold FListim (e.g., via epidural stimulation) and neurochemicals should be tested in vivo to improve locomotor rehabilitation after injury. In fact, reactivation of spinal locomotor circuits by conventional electrical stimulation of afferent fibers is difficult, while pharmacological activation of spinal networks is clinically impracticable due to concurrent unwanted effects. We speculate that associating subthreshold chemical and electrical inputs might decrease side effects when attempting to evoke human locomotor patterns. PMID:22956799

  14. A combined electrophysiological and morphological study of neuropeptide Y–expressing inhibitory interneurons in the spinal dorsal horn of the mouse

    PubMed Central

    Iwagaki, Noboru; Ganley, Robert P.; Dickie, Allen C.; Polgár, Erika; Hughes, David I.; Del Rio, Patricia; Revina, Yulia; Watanabe, Masahiko; Todd, Andrew J.; Riddell, John S.

    2015-01-01

    Abstract The spinal dorsal horn contains numerous inhibitory interneurons that control transmission of somatosensory information. Although these cells have important roles in modulating pain, we still have limited information about how they are incorporated into neuronal circuits, and this is partly due to difficulty in assigning them to functional populations. Around 15% of inhibitory interneurons in laminae I-III express neuropeptide Y (NPY), but little is known about this population. We therefore used a combined electrophysiological/morphological approach to investigate these cells in mice that express green fluorescent protein (GFP) under control of the NPY promoter. We show that GFP is largely restricted to NPY-immunoreactive cells, although it is only expressed by a third of those in lamina I-II. Reconstructions of recorded neurons revealed that they were morphologically heterogeneous, but never islet cells. Many NPY-GFP cells (including cells in lamina III) appeared to be innervated by C fibres that lack transient receptor potential vanilloid-1, and consistent with this, we found that some lamina III NPY-immunoreactive cells were activated by mechanical noxious stimuli. Projection neurons in lamina III are densely innervated by NPY-containing axons. Our results suggest that this input originates from a small subset of NPY-expressing interneurons, with the projection cells representing only a minority of their output. Taken together with results of previous studies, our findings indicate that somatodendritic morphology is of limited value in classifying functional populations among inhibitory interneurons in the dorsal horn. Because many NPY-expressing cells respond to noxious stimuli, these are likely to have a role in attenuating pain and limiting its spread. PMID:26882346

  15. Interactions between Dorsal and Ventral Root Stimulation on the Generation of Locomotor-Like Activity in the Neonatal Mouse Spinal Cord.

    PubMed

    Pujala, Avinash; Blivis, Dvir; O'Donovan, Michael J

    2016-01-01

    We investigated whether dorsal (DR) and ventral root (VR) stimulus trains engage common postsynaptic components to activate the central pattern generator (CPG) for locomotion in the neonatal mouse spinal cord. VR stimulation did not activate the first order interneurons mediating the activation of the locomotor CPG by sacrocaudal afferent stimulation. Simultaneous stimulation of adjacent dorsal or ventral root pairs, subthreshold for evoking locomotor-like activity, did not summate to activate the CPG. This suggests that locomotor-like activity is triggered when a critical class of efferent or afferent axons is stimulated and does not depend on the number of stimulated axons or activated postsynaptic neurons. DR- and VR-evoked episodes exhibited differences in the coupling between VR pairs. In DR-evoked episodes, the coupling between the ipsilateral and contralateral flexor/extensor roots was similar and stronger than the bilateral extensor roots. In VR-evoked episodes, ipsilateral flexor/extensor coupling was stronger than both the contralateral flexor/extensor and the bilateral extensor coupling. For both types of stimulation, the coupling was greatest between the bilateral L1/L2 flexor-dominated roots. This indicates that the recruitment and/or the firing pattern of motoneurons differed in DR and VR-evoked episodes. However, the DR and VR trains do not appear to activate distinct CPGs because trains of DR and VR stimuli at frequencies too low to evoke locomotor-like activity did so when they were interleaved. These results indicate that the excitatory actions of VR stimulation converge onto the CPG through an unknown pathway that is not captured by current models of the locomotor CPG. PMID:27419215

  16. Interactions between Dorsal and Ventral Root Stimulation on the Generation of Locomotor-Like Activity in the Neonatal Mouse Spinal Cord

    PubMed Central

    2016-01-01

    Abstract We investigated whether dorsal (DR) and ventral root (VR) stimulus trains engage common postsynaptic components to activate the central pattern generator (CPG) for locomotion in the neonatal mouse spinal cord. VR stimulation did not activate the first order interneurons mediating the activation of the locomotor CPG by sacrocaudal afferent stimulation. Simultaneous stimulation of adjacent dorsal or ventral root pairs, subthreshold for evoking locomotor-like activity, did not summate to activate the CPG. This suggests that locomotor-like activity is triggered when a critical class of efferent or afferent axons is stimulated and does not depend on the number of stimulated axons or activated postsynaptic neurons. DR- and VR-evoked episodes exhibited differences in the coupling between VR pairs. In DR-evoked episodes, the coupling between the ipsilateral and contralateral flexor/extensor roots was similar and stronger than the bilateral extensor roots. In VR-evoked episodes, ipsilateral flexor/extensor coupling was stronger than both the contralateral flexor/extensor and the bilateral extensor coupling. For both types of stimulation, the coupling was greatest between the bilateral L1/L2 flexor-dominated roots. This indicates that the recruitment and/or the firing pattern of motoneurons differed in DR and VR-evoked episodes. However, the DR and VR trains do not appear to activate distinct CPGs because trains of DR and VR stimuli at frequencies too low to evoke locomotor-like activity did so when they were interleaved. These results indicate that the excitatory actions of VR stimulation converge onto the CPG through an unknown pathway that is not captured by current models of the locomotor CPG. PMID:27419215

  17. Osteolysis and Cervical Cord Compression Secondary to Silicone Granuloma Formation around a Dorsal Spinal Cord Stimulator: A Case Report

    PubMed Central

    Dimar, John R.; Endriga, David T.; Carreon, Leah Y.

    2016-01-01

    Spinal cord stimulators (SCSs) have long been in use as a modality for the management of numerous pain pathologies. Along with commonly anticipated morbidities such as displacement, failure (due to fracture or breakage), or infection, there have also been rare but well-documented complications of fibrous scarring, resulting in spinal cord compression. This is the first known case that demonstrates osteolysis and bony destruction of the vertebrae adjacent to the SCS along with the foreign-body granulomatous reaction. A 61-year-old man who underwent prior posterior cervical implantation with an SCS followed by multiple revisions presented with progressive paresthesias, numbness, and weakness of his upper extremities 10 years later. The SCS was removed followed by decompression, and instrumented fusion of the cervical spine. Histopathologic analysis reveals foreign-body reaction to the SCS and its silicone debris. Tissue cultures were negative for bacterial, fungal, or mycobacterial infection. No malignancy was seen. The current case illustrates the inherent possibility of foreign-body granulomatous reactions with SCS and its silicone particulate matter, made unique in this instance by the associated bony destruction of the adjacent vertebrae. PMID:27247910

  18. Osteolysis and Cervical Cord Compression Secondary to Silicone Granuloma Formation around a Dorsal Spinal Cord Stimulator: A Case Report.

    PubMed

    Dimar, John R; Endriga, David T; Carreon, Leah Y

    2016-06-01

    Spinal cord stimulators (SCSs) have long been in use as a modality for the management of numerous pain pathologies. Along with commonly anticipated morbidities such as displacement, failure (due to fracture or breakage), or infection, there have also been rare but well-documented complications of fibrous scarring, resulting in spinal cord compression. This is the first known case that demonstrates osteolysis and bony destruction of the vertebrae adjacent to the SCS along with the foreign-body granulomatous reaction. A 61-year-old man who underwent prior posterior cervical implantation with an SCS followed by multiple revisions presented with progressive paresthesias, numbness, and weakness of his upper extremities 10 years later. The SCS was removed followed by decompression, and instrumented fusion of the cervical spine. Histopathologic analysis reveals foreign-body reaction to the SCS and its silicone debris. Tissue cultures were negative for bacterial, fungal, or mycobacterial infection. No malignancy was seen. The current case illustrates the inherent possibility of foreign-body granulomatous reactions with SCS and its silicone particulate matter, made unique in this instance by the associated bony destruction of the adjacent vertebrae. PMID:27247910

  19. P2Y13 receptor-mediated rapid increase in intracellular calcium induced by ADP in cultured dorsal spinal cord microglia.

    PubMed

    Zeng, Junwei; Wang, Gaoxia; Liu, Xiaohong; Wang, Chunmei; Tian, Hong; Liu, Aidong; Jin, Huan; Luo, Xiaomei; Chen, Yuanshou

    2014-11-01

    P2Y receptors have been implicated in the calcium mobilization by the response to neuroexcitatory substances in neurons and astrocytes, but little is known about P2Y receptors in microglia cells. In the present study, the effects of ADP on the intracellular calcium concentration ([Ca(2+)]i) in cultured dorsal spinal cord microglia were detected with confocal laser scanning microscopy using fluo-4/AM as a calcium fluorescence indicator that could monitor real-time alterations of [Ca(2+)]i. Here we show that ADP (0.01-100 μM) causes a rapid increase in [Ca(2+)]i with a dose-dependent manner in cultured microglia. The action of ADP on [Ca(2+)]i was significantly blocked by MRS2211 (a selective P2Y13 receptor antagonist), but was unaffected by MRS2179 (a selective P2Y1 receptor antagonist) or MRS2395 (a selective P2Y12 receptor antagonist), which suggest that P2Y13 receptor may be responsible for ADP-evoked Ca(2+) mobilization in cultured microglia. P2Y13-evoked Ca(2+) response can be obviously inhibited by BAPTA-AM and U-73122, respectively. Moreover, removal of extracellular Ca(2+) (by EGTA) also can obvious suppress the Ca(2+) mobilization. These results means both intracellular calcium and extracellular calcium are potentially important mechanisms in P2Y13 receptor-evoked Ca(2+) mobilization. However, P2Y13 receptor-evoked Ca(2+) response was not impaired after CdCl2 and verapamil administration, which suggest that voltage-operated Ca(2+) channels may be not related with P2Y13-evoked Ca(2+) response. In addition, Ca(2+) mobilization induced by ADP was abolished by different store-operated Ca(2+) channels (SOCs) blocker, 2-APB (50 μM) and SKF-96365 (1 mM), respectively. These observations suggest that the activation of P2Y13 receptor might be involved in the effect of ADP on [Ca(2+)]i in cultured dorsal spinal cord microglia. Furthermore, our results raise a possibility that P2Y13 receptor activation causes Ca(2+) release from Ca(2+) store, which leads to the

  20. The effect of glycyrrhizic acid on traumatic spinal cord injury in rats.

    PubMed

    Sehitoglu, M H; Guven, M; Yüksel, Y; Akman, T; Bozkurt Aras, A; Farooqi, A A; Cosar, M

    2016-01-01

    Spine injury associated with traumatic spinal cord injury eventuates in oxidative stress, inflammation and neuronal apoptosis. The aim of this study is to find out whether the glycyrrhizic acid treatment protects spinal cord from traumatic injuries in rats. To this end, the rats were divided into three groups: group I; control group (no drug or operation, n=8), group II; traumatic spinal cord injury group (TSCI, n=8) and group III; glycyrrhizic acid group (TSCI-GA, 80 mg/kg, n=8). Total laminectomy was performed at T10 level. A balloon angioplasty catheter was inserted into the T9 level thoracic spinal cord extradurally. The rats were evaluated with the Tarlov Scale. After 24 hours, spinal cord tissues were taken for biochemical and histopathological examinations. TSCI effectuates unwanted results on tissues, antioxidant systems and cell membranes. Antioxidant enzyme level decreased and lipid peroxidation increased. However, TSCI led to inflammation and apoptosis. Glycyrrhizic acid treatment provided a significant decrease in lipid peroxidation in group III in comparison with group II. Moreover, nuclear respiratory factor 1 levels and superoxide dismutase activity of group III were significantly higher than group II (p<0.05). The histopathological and immunohistochemical results revealed that the numbers of apoptotic and necrotic neuron, edema, hemorrhage, inflammatory cells, NF-κB and S100B expressions were significantly lower than group II (p<0.05). Our study showed that the glycyrrhizic acid treatment reduced oxidative stress and inflammation, and promoted the neuronal functions in traumatic spinal cord injury. PMID:27188862

  1. Neuroprotective effect of epidural hypothermia after spinal cord lesion in rats

    PubMed Central

    Barbosa, Marcello Oliveira; Cristante, Alexandre Fogaça; dos Santos, Gustavo Bispo; Ferreira, Ricardo; Marcon, Raphael Martus; de Barros Filho, Tarcisio Eloy Pessoa

    2014-01-01

    OBJECTIVES : To evaluate the neuroprotective effect of epidural hypothermia in rats subjected to experimental spinal cord lesion. METHODS: Wistar rats (n = 30) weighing 320-360 g were randomized to two groups (hypothermia and control) of 15 rats per group. A spinal cord lesion was induced by the standardized drop of a 10-g weight from a height of 2.5 cm, using the New York University Impactor, after laminectomy at the T9-10 level. Rats in the hypothermia group underwent epidural hypothermia for 20 minutes immediately after spinal cord injury. Motor function was assessed for six weeks using the Basso, Beattie and Bresnahan motor scores and the inclined plane test. At the end of the final week, the rats' neurological status was monitored by the motor evoked potential test and the results for the two groups were compared. RESULTS: Analysis of the Basso, Beattie and Bresnahan scores obtained during the six-week period indicated that there were no significant differences between the two groups. There was no significant difference between the groups in the inclined plane test scores during the six-week period. Furthermore, at the end of the study, the latency and amplitude values of the motor evoked potential test were not significantly different between the two groups. CONCLUSION: Hypothermia did not produce a neuroprotective effect when applied at the injury level and in the epidural space immediately after induction of a spinal cord contusion in Wistar rats. PMID:25141116

  2. Nanomolar oxytocin synergizes with weak electrical afferent stimulation to activate the locomotor CpG of the rat spinal cord in vitro.

    PubMed

    Dose, Francesco; Zanon, Patrizia; Coslovich, Tamara; Taccola, Giuliano

    2014-01-01

    Synergizing the effect of afferent fibre stimulation with pharmacological interventions is a desirable goal to trigger spinal locomotor activity, especially after injury. Thus, to better understand the mechanisms to optimize this process, we studied the role of the neuropeptide oxytocin (previously shown to stimulate locomotor networks) on network and motoneuron properties using the isolated neonatal rat spinal cord. On motoneurons oxytocin (1 nM-1 μM) generated sporadic bursts with superimposed firing and dose-dependent depolarization. No desensitization was observed despite repeated applications. Tetrodotoxin completely blocked the effects of oxytocin, demonstrating the network origin of the responses. Recording motoneuron pool activity from lumbar ventral roots showed oxytocin mediated depolarization with synchronous bursts, and depression of reflex responses in a stimulus and peptide-concentration dependent fashion. Disinhibited bursting caused by strychnine and bicuculline was accelerated by oxytocin whose action was blocked by the oxytocin antagonist atosiban. Fictive locomotion appeared when subthreshold concentrations of NMDA plus 5HT were coapplied with oxytocin, an effect prevented after 24 h incubation with the inhibitor of 5HT synthesis, PCPA. When fictive locomotion was fully manifested, oxytocin did not change periodicity, although cycle amplitude became smaller. A novel protocol of electrical stimulation based on noisy waveforms and applied to one dorsal root evoked stereotypic fictive locomotion. Whenever the stimulus intensity was subthreshold, low doses of oxytocin triggered fictive locomotion although oxytocin per se did not affect primary afferent depolarization evoked by dorsal root pulses. Among the several functional targets for the action of oxytocin at lumbar spinal cord level, the present results highlight how small concentrations of this peptide could bring spinal networks to threshold for fictive locomotion in combination with other

  3. Basic properties of somatosensory-evoked responses in the dorsal hippocampus of the rat.

    PubMed

    Bellistri, Elisa; Aguilar, Juan; Brotons-Mas, Jorge R; Foffani, Guglielmo; de la Prida, Liset Menendez

    2013-05-15

    The hippocampus is a pivotal structure for episodic memory function. This ability relies on the possibility of integrating different features of sensory stimuli with the spatio-temporal context in which they occur. While recent studies now suggest that somatosensory information is already processed by the hippocampus, the basic mechanisms still remain unexplored. Here, we used electrical stimulation of the paws, the whisker pad or the medial lemniscus to probe the somatosensory pathway to the hippocampus in the anaesthetized rat, and multisite electrodes, in combination with tetrode and intracellular recordings, to look at the properties of somatosensory hippocampal responses. We found that peripheral and lemniscal stimulation elicited small local field potential responses in the dorsal hippocampus about 35-40 ms post-stimulus. Current source density analysis established the local nature of these responses, revealing associated synaptic sinks that were consistently confined to the molecular layer (ML) of the dentate gyrus (DG), with less regular activation of the CA1 stratum lacunosum moleculare (SLM). A delayed (40-45 ms), potentially active, current source that outlasted the SLM sink was present in about 50% cases around the CA1 pyramidal cell layer. Somatosensory stimulation resulted in multi-unit firing increases in the majority of DG responses (79%), whereas multi-unit firing suppression was observed in the majority of CA1 responses (62%). Tetrode and intracellular recordings of individual cells confirmed different firing modulation in the DG and the CA1 region, and verified the active nature of both the early ML sink and delayed somatic CA1 source. Hippocampal responses to somatosensory stimuli were dependent on fluctuations in the strength and composition of synaptic inputs due to changes of the ongoing local (hippocampal) and distant (cortical) state. We conclude that somatosensory signals reach the hippocampus mainly from layer II entorhinal cortex to

  4. Immunocytochemical identification of substance P cells and their processes in rat sensory ganglia and their terminals in the spinal cord: Light microscopic studies

    PubMed Central

    Chan-Palay, Victoria; Palay, Sanford L.

    1977-01-01

    The indirect immunofluorescence method and the unlabeled primary antibody peroxidase antiperoxidase method are used to demonstrate the substance P (SP) plexus in the spinal cord and SP cells in the sensory ganglia of the rat. The normal untreated and the control side of the dorsal rhizotomized rat show vast SP immunoreactive plexuses in the substantia gelatinosa, central gray, and ventral gray regions of the spinal cord. In each sensory ganglion, approximately 250 SP immunoreactive cells are found singly or in small groups of 2 or 3, near blood capillaries or among ganglion and satellite cells. They contain intensely immunoreactive cytoplasmic granules 0.1-3.0 μm across. Occasionally, free intensely immunoreactive granules are found in the surrounding tissue near an SP cell but not clearly within the confines of the cell. Another type of immunoreaction has been observed with both methods. A less intense, homogeneous reactivity has been found in lamellae insinuated between ganglion cells and near blood capillaries close to an SP cell; the characteristic disposition of this homogeneous reactivity suggests an extracellular location. Unilateral rhizotomy results in an increased number of immunoreactive SP cells and nerve fibers as well as a more extensive homogeneous immunoreactivity. These results add to existing evidence that SP cells in sensory ganglia send fibers via the dorsal roots to the spinal cord. SP cells, fibers, and terminals do not take up exogenously applied 125I-labeled [Tyr8]SP and cannot be demonstrated by subsequent autoradiography. No neurotensin immunoreactive cells were found in sensory ganglia. Images PMID:333442

  5. Leuprolide acetate induces structural and functional recovery of injured spinal cord in rats.

    PubMed

    Díaz Galindo, Carmen; Gómez-González, Beatriz; Salinas, Eva; Calderón-Vallejo, Denisse; Hernández-Jasso, Irma; Bautista, Eduardo; Quintanar, J Luis

    2015-11-01

    Gonadotropin-releasing hormone (GnRH) and its synthetic analog leuprolide acetate, a GnRH agonist, have neurotrophic properties. This study was designed to determine whether administration of leuprolide acetate can improve locomotor behavior, gait, micturition reflex, spinal cord morphology and the amount of microglia in the lesion epicenter after spinal cord injury in rats. Rats with spinal cord compression injury were administered leuprolide acetate or saline solution for 5 weeks. At the 5(th) week, leuprolide acetate-treated rats showed locomotor activity recovery by 38%, had improvement in kinematic gait and exhibited voiding reflex recovery by 60%, as compared with the 1(st) week. By contrast, saline solution-treated rats showed locomotor activity recovery only by 7%, but voiding reflex did not recover. More importantly, leuprolide acetate treatment reduced microglial immunological reaction and induced a trend towards greater area of white and gray matter in the spinal cord. Therefore, leuprolide acetate has great potential to repair spinal cord injury. PMID:26807118

  6. Leuprolide acetate induces structural and functional recovery of injured spinal cord in rats

    PubMed Central

    Díaz Galindo, Carmen; Gómez-González, Beatriz; Salinas, Eva; Calderón-Vallejo, Denisse; Hernández-Jasso, Irma; Bautista, Eduardo; Quintanar, J Luis

    2015-01-01

    Gonadotropin-releasing hormone (GnRH) and its synthetic analog leuprolide acetate, a GnRH agonist, have neurotrophic properties. This study was designed to determine whether administration of leuprolide acetate can improve locomotor behavior, gait, micturition reflex, spinal cord morphology and the amount of microglia in the lesion epicenter after spinal cord injury in rats. Rats with spinal cord compression injury were administered leuprolide acetate or saline solution for 5 weeks. At the 5th week, leuprolide acetate-treated rats showed locomotor activity recovery by 38%, had improvement in kinematic gait and exhibited voiding reflex recovery by 60%, as compared with the 1st week. By contrast, saline solution-treated rats showed locomotor activity recovery only by 7%, but voiding reflex did not recover. More importantly, leuprolide acetate treatment reduced microglial immunological reaction and induced a trend towards greater area of white and gray matter in the spinal cord. Therefore, leuprolide acetate has great potential to repair spinal cord injury. PMID:26807118

  7. Time-related effects of general functional training in spinal cord-injured rats

    PubMed Central

    Miranda, Taisa Amoroso Bortolato; Vicente, Juliana Mendes Yule; Marcon, Raphael Martus; Cristante, Alexandre Fogaça; Morya, Edgard; do Valle, Angela Cristina

    2012-01-01

    OBJECTIVES: This prospective, randomized, experimental study with rats aimed to investigate the influence of general treatment strategies on the motor recovery of Wistar rats with moderate contusive spinal cord injury. METHODS: A total of 51 Wistar rats were randomized into five groups: control, maze, ramp, runway, and sham (laminectomy only). The rats underwent spinal cord injury at the T9-T10 levels using the NYU-Impactor. Each group was trained for 12 minutes twice a week for two weeks before and five weeks after the spinal cord injury, except for the control group. Functional motor recovery was assessed with the Basso, Beattie, and Bresnahan Scale on the first postoperative day and then once a week for five weeks. The animals were euthanized, and the spinal cords were collected for histological analysis. RESULTS: Ramp and maze groups showed an earlier and greater functional improvement effect than the control and runway groups. However, over time, unexpectedly, all of the groups showed similar effects as the control group, with spontaneous recovery. There were no histological differences in the injured area between the trained and control groups. CONCLUSION: Short-term benefits can be associated with a specific training regime; however, the same training was ineffective at maintaining superior long-term recovery. These results might support new considerations before hospital discharge of patients with spinal cord injuries. PMID:22892926

  8. Tail arteries from chronically spinalized rats have potentiated responses to nerve stimulation in vitro

    PubMed Central

    Yeoh, Melanie; McLachlan, Elspeth M; Brock, James A

    2004-01-01

    Patients with severe spinal cord lesions that damage descending autonomic pathways generally have low resting arterial pressure but bladder or colon distension or unheeded injuries may elicit a life-threatening hypertensive episode. Such episodes (known as autonomic dysreflexia) are thought to result from the loss of descending baroreflex inhibition and/or plasticity within the spinal cord. However, it is not clear whether changes in the periphery contribute to the exaggerated reflex vasoconstriction. The effects of spinal transection at T7–8 on nerve- and agonist-evoked contractions of the rat tail artery were investigated in vitro. Isometric contractions of arterial segments were recorded and responses of arteries from spinalized animals (‘spinalized arteries’) and age-matched and sham-operated controls were compared. Two and eight weeks after transection, nerve stimulation at 0.1–10 Hz produced contractions of greater force and duration in spinalized arteries. At both stages, the α-adrenoceptor antagonists prazosin (10 nm) and idazoxan (0.1 μm) produced less blockade of nerve-evoked contraction in spinalized arteries. Two weeks after transection, spinalized arteries were supersensitive to the α1-adrenoceptor agonist phenylephrine, and the α2-adrenoceptor agonist, clonidine, but 8 weeks after transection, spinalized arteries were supersensitive only to clonidine. Contractions of spinalized arteries elicited by 60 mm K+ were larger and decayed more slowly at both stages. These findings demonstrate that spinal transection markedly increases nerve-evoked contractions and this can, in part, be accounted for by increased reactivity of the vascular smooth muscle to vasoconstrictor agents. This hyper-reactivity may contribute to the genesis of autonomic dysreflexia in patients. PMID:14766944

  9. The Neuroprotective Effect of Kefir on Spinal Cord Ischemia/Reperfusion Injury in Rats

    PubMed Central

    Akman, Tarik; Yener, Ali Umit; Sehitoglu, Muserref Hilal; Yuksel, Yasemin; Cosar, Murat

    2015-01-01

    Objective The main causes of spinal cord ischemia are a variety of vascular pathologies causing acute arterial occlusions. We investigated neuroprotective effects of kefir on spinal cord ischemia injury in rats. Methods Rats were divided into three groups : 1) sham operated control rats; 2) spinal cord ischemia group fed on a standard diet without kefir pretreatment; and 3) spinal cord ischemia group fed on a standard diet plus kefir. Spinal cord ischemia was performed by the infrarenal aorta cross-clamping model. The spinal cord was removed after the procedure. The biochemical and histopathological changes were observed within the samples. Functional assessment was performed for neurological deficit scores. Results The kefir group was compared with the ischemia group, a significant decrease in malondialdehyde levels was observed (p<0.05). Catalase and superoxide dismutase levels of the kefir group were significantly higher than ischemia group (p<0.05). In histopathological samples, the kefir group is compared with ischemia group, there was a significant decrease in numbers of dead and degenerated neurons (p<0.05). In immunohistochemical staining, hipoxia-inducible factor-1α and caspase 3 immunopositive neurons were significantly decreased in kefir group compared with ischemia group (p<0.05). The neurological deficit scores of kefir group were significantly higher than ischemia group at 24 h (p<0.05). Conclusion Our study revealed that kefir pretreatment in spinal cord ischemia/reperfusion reduced oxidative stress and neuronal degeneration as a neuroprotective agent. Ultrastructural studies are required in order for kefir to be developed as a promising therapeutic agent to be utilized for human spinal cord ischemia in the future. PMID:26113960

  10. Bortezomib Treatment Produces Nocifensive Behavior and Changes in the Expression of TRPV1, CGRP, and Substance P in the Rat DRG, Spinal Cord, and Sciatic Nerve

    PubMed Central

    Quartu, M.; Carozzi, V. A.; Dorsey, S. G.; Serra, M. P.; Poddighe, L.; Picci, C.; Boi, M.; Melis, T.; Del Fiacco, M.; Meregalli, C.; Chiorazzi, A.; Renn, C. L.; Cavaletti, G.; Marmiroli, P.

    2014-01-01

    To investigate neurochemical changes associated with bortezomib-induced painful peripheral neuropathy (PN), we examined the effects of a single-dose intravenous administration of bortezomib and a well-established “chronic” schedule in a rat model of bortezomib-induced PN. The TRPV1 channel and sensory neuropeptides CGRP and substance P (SP) were studied in L4-L5 dorsal root ganglia (DRGs), spinal cord, and sciatic nerve. Behavioral measures, performed at the end of the chronic bortezomib treatment, confirmed a reduction of mechanical nociceptive threshold, whereas no difference occurred in thermal withdrawal latency. Western blot analysis showed a relative increase of TRPV1 in DRG and spinal cord after both acute and chronic bortezomib administration. Reverse transcriptase-polymerase chain reaction revealed a decrease of TRPV1 and CGRP mRNA relative levels after chronic treatment. Immunohistochemistry showed that in the DRGs, TRPV1-, CGRP-, and SP-immunoreactive neurons were mostly small- and medium-sized and the proportion of TRPV1- and CGRP-labeled neurons increased after treatment. A bortezomib-induced increase in density of TRPV1- and CGRP-immunoreactive innervation in the dorsal horn was also observed. Our findings show that bortezomib-treatment selectively affects subsets of DRG neurons likely involved in the processing of nociceptive stimuli and that neurochemical changes may contribute to development and persistence of pain in bortezomib-induced PN. PMID:24877063

  11. Effects of polarization in low-level laser therapy of spinal cord injury in rats

    NASA Astrophysics Data System (ADS)

    Ando, Takahiro; Sato, Shunichi; Kobayashi, Hiroaki; Nawashiro, Hiroshi; Ashida, Hiroshi; Hamblin, Michael R.; Obara, Minoru

    2012-03-01

    Low-level laser therapy (LLLT) is a promising approach to treat the spinal cord injury (SCI). Since nerve fibers have optical anisotropy, propagation of light in the spinal tissue might be affected by its polarization direction. However, the effect of polarization on the efficacy of LLLT has not been elucidated. In the present study, we investigated the effect of polarization on the efficacy of near-infrared LLLT for SCI. Rat spinal cord was injured with a weight-drop device. The lesion site was irradiated with an 808-nm diode laser beam that was transmitted through a polarizing filter immediately after injury and daily for five consecutive days. The laser power at the injured spinal cord surface was 25 mW, and the dosage per day was 9.6 J/cm2 (spot diameter, 2 cm; irradiation duration, 1200 s). Functional recovery was assessed daily by an open-field test. The results showed that the functional scores of the SCI rats that were treated with 808-nm laser irradiation were significantly higher than those of the SCI alone group (Group 1) from day 5 after injury, regardless of the polarization direction. Importantly, as compared to the locomotive function of the SCI rats that were treated with the perpendicularly-polarized laser parallel to the spinal column (Group 2), that of the SCI rats that were irradiated with the linearly aligned polarization (Group 3) was significantly improved from day 10 after injury. In addition, the ATP contents in the injured spinal tissue of Group 3, which were measured immediately after laser irradiation, were moderately higher than those of Group 2. These observations are attributable to the deeper penetration of the parallelpolarized light in the anisotropic spinal tissue, suggesting that polarization direction significantly affects the efficacy of LLLT for SCI.

  12. Dorsal hippocampal NMDA receptors mediate the interactive effects of arachidonylcyclopropylamide and MDMA/ecstasy on memory retrieval in rats.

    PubMed

    Ghaderi, Marzieh; Rezayof, Ameneh; Vousooghi, Nasim; Zarrindast, Mohammad-Reza

    2016-04-01

    A combination of cannabis and ecstasy may change the cognitive functions more than either drug alone. The present study was designed to investigate the possible involvement of dorsal hippocampal NMDA receptors in the interactive effects of arachidonylcyclopropylamide (ACPA) and ecstasy/MDMA on memory retrieval. Adult male Wistar rats were cannulated into the CA1 regions of the dorsal hippocampus (intra-CA1) and memory retrieval was examined using the step-through type of passive avoidance task. Intra-CA1 microinjection of a selective CB1 receptor agonist, ACPA (0.5-4ng/rat) immediately before the testing phase (pre-test), but not after the training phase (post-training), impaired memory retrieval. In addition, pre-test intra-CA1 microinjection of MDMA (0.5-1μg/rat) dose-dependently decreased step-through latency, indicating an amnesic effect of the drug by itself. Interestingly, pre-test microinjection of a higher dose of MDMA into the CA1 regions significantly improved ACPA-induced memory impairment. Moreover, pre-test intra-CA1 microinjection of a selective NMDA receptor antagonist, D-AP5 (1 and 2μg/rat) inhibited the reversal effect of MDMA on the impairment of memory retrieval induced by ACPA. Pre-test intra-CA1 microinjection of the same doses of D-AP5 had no effect on memory retrieval alone. These findings suggest that ACPA or MDMA consumption can induce memory retrieval impairment, while their co-administration improves this amnesic effect through interacting with hippocampal glutamatergic-NMDA receptor mechanism. Thus, it seems that the tendency to abuse cannabis with ecstasy may be for avoiding cognitive dysfunction. PMID:26612394

  13. Disinhibition by propranolol and chlordiazepoxide of nonrewarded lever-pressing in the rat is unaffected by dorsal noradrenergic bundle lesion.

    PubMed

    Salmon, P; Tsaltas, E; Gray, J A

    1989-03-01

    Ten male Sprague-Dawley rats received 6-hydroxydopamine-induced lesions of the dorsal noradrenergic bundle and 10 others underwent control operations. The lesion depleted levels of noradrenaline in the hippocampus to 2% of those in the controls. All rats were then trained for 16 sessions to lever-press in a Skinner box on a variable interval 18 sec schedule of food-reinforcement, then for 42 days on a successive discrimination between periods of variable interval (VI 18 sec) food-reinforcement and periods of extinction. This report describes the effects of chlordiazepoxide (CDP; 5 mg/kg) and propranolol (5 and 10 mg/kg) injected intraperitoneally in both groups on modified ABBA designs after this training. Both drugs increased the response rates in extinction periods. The effect of propranolol was similar at each dose and smaller than that of CDP. Although CDP and propranolol (5 mg/kg) increased variable interval response rates also, this could not account for the effect on extinction response rates. Responding did not differ between the lesioned and control animals and the effects of drugs were similar in each group. It is unlikely that CDP or propranolol release nonrewarded responding by disrupting transmission in the dorsal noradrenergic bundle. PMID:2725847

  14. Effect of oscillating electrical field stimulation on motor function recovery and myelin regeneration after spinal cord injury in rats

    PubMed Central

    Tian, Da-Sheng; Jing, Jue-Hua; Qian, Jun; Chen, Lei; Zhu, Bin

    2016-01-01

    [Purpose] The aim of this study was to evaluate the effect of oscillating electrical field stimulation on motor function recovery and myelin regeneration in rats with spinal cord injury. [Subjects and Methods] A rat model of spinal cord injury was constructed by using the Allen weight-drop method. These rats were randomly divided into normal, spinal cord injury, and spinal cord injury + oscillating electrical field stimulation groups. The experimental group received the intervention with oscillating electrical field stimulation, and the control group received the intervention with an electrical field stimulator without oscillating electrical field stimulation. Each group was then randomly divided into seven subgroups according to observation time (1, 2, 4, 6, 8, 10, and 12 weeks). Basso-Beattie-Bresnahan score and inclined plate test score evaluation, motor evoked potential detection, and histological observation were performed. [Results] In the first 2 weeks of oscillating electrical field stimulation, the oscillating electrical field stimulation and inclined plate test scores of spinal cord injury group and spinal cord injury + oscillating electrical field stimulation group were not significantly different. In the fourth week, the scores of the spinal cord injury group were significantly lower than those of the spinal cord injury + oscillating electrical field stimulation group. The motor evoked potential incubation period in the spinal cord injury + oscillating electrical field stimulation group at the various time points was shorter than that in the spinal cord injury group. In the sixth week, the relative area of myelin in the spinal cord injury + oscillating electrical field stimulation group was evidently larger than that in the spinal cord injury group. [Conclusion] Oscillating electrical field stimulation could effectively improve spinal cord conduction function and promote motor function recovery in rats with spinal cord injury, as well as promote myelin

  15. Effect of oscillating electrical field stimulation on motor function recovery and myelin regeneration after spinal cord injury in rats.

    PubMed

    Tian, Da-Sheng; Jing, Jue-Hua; Qian, Jun; Chen, Lei; Zhu, Bin

    2016-05-01

    [Purpose] The aim of this study was to evaluate the effect of oscillating electrical field stimulation on motor function recovery and myelin regeneration in rats with spinal cord injury. [Subjects and Methods] A rat model of spinal cord injury was constructed by using the Allen weight-drop method. These rats were randomly divided into normal, spinal cord injury, and spinal cord injury + oscillating electrical field stimulation groups. The experimental group received the intervention with oscillating electrical field stimulation, and the control group received the intervention with an electrical field stimulator without oscillating electrical field stimulation. Each group was then randomly divided into seven subgroups according to observation time (1, 2, 4, 6, 8, 10, and 12 weeks). Basso-Beattie-Bresnahan score and inclined plate test score evaluation, motor evoked potential detection, and histological observation were performed. [Results] In the first 2 weeks of oscillating electrical field stimulation, the oscillating electrical field stimulation and inclined plate test scores of spinal cord injury group and spinal cord injury + oscillating electrical field stimulation group were not significantly different. In the fourth week, the scores of the spinal cord injury group were significantly lower than those of the spinal cord injury + oscillating electrical field stimulation group. The motor evoked potential incubation period in the spinal cord injury + oscillating electrical field stimulation group at the various time points was shorter than that in the spinal cord injury group. In the sixth week, the relative area of myelin in the spinal cord injury + oscillating electrical field stimulation group was evidently larger than that in the spinal cord injury group. [Conclusion] Oscillating electrical field stimulation could effectively improve spinal cord conduction function and promote motor function recovery in rats with spinal cord injury, as well as promote myelin

  16. S-nitroso-l-cysteine releases norepinephrine in rat spinal synaptosomes.

    PubMed

    Li, X; Rose, G; Dongre, N; Pan, H L; Tobin, J R; Eisenach, J C

    2000-07-28

    Although nitric oxide (NO) participates in development of hypersensitivity states in the spinal cord thought to underlie chronic pain, it also participates in analgesia produced by various drugs. In rats with a hypersensitivity state following peripheral nerve injury, spinal administration of an NO donor or l-cysteine alone produced no effect, whereas their combination, which yields s-nitroso-l-cysteine (SNC) powerfully reduced hypersensitivity. In the current study, we examined the ability of SNC to stimulate release of a known spinal analgesic neurotransmitter, norepinephrine (NE), as a possible mechanism of analgesic action of NO in the spinal cord. SNC (but not the NO donor alone or decomposed SNC) produced a concentration-dependent release of NE from rat spinal cord synaptosomes. The d-isomer of SNC was less potent than the l-isomer, and the effect of SNC was partially blocked by l-, but not d-leucine, implicating an interaction with the l-amino acid transporter. SNC-induced NE release was partially Na(+) dependent, but largely Ca(2+) independent. NE uptake inhibitors partially antagonized the effect of SNC, but guanylate cyclase inhibitors were without effect. These data are therefore consistent with NO stimulating NE release in the spinal cord via reaction with thiol containing compounds, such as cysteine, entry into NE terminals via active transport, and production of both exocytotic and carrier mediated release. PMID:10924712

  17. High Oestradiol Replacement Reverses Response Memory Bias in Ovariectomised Female Rats Regardless of Dopamine Levels in the Dorsal Striatum.

    PubMed

    Hussain, D; Cossette, M-P; Brake, W G

    2016-05-01

    Oestrogens influence memory system bias in female rats such that high levels of oestrogen are associated with place (or spatial) memory use, and low oestrogen levels with response (or habitual) memory use. Moreover, striatal-dependent response memory is sensitive to dopamine transmission in the dorsal striatum, and oestrogens have been shown to affect dopamine release in that brain area. In the present study, the effects of oestrogens and dopamine transmission on multiple memory system bias were explored in ovariectomised rats receiving low or high 17β-oestradiol replacement under saline, autoreceptor-activating doses of the dopamine D2 receptor agonist, apomorphine (50 and 80 μg/kg), or amphetamine (0.5 mg/kg) administration. Furthermore, dorsal striatal dopamine release was measured after administration of the same drug conditions using in vivo microdialysis. As expected, high oestradiol rats predominantly used place memory, whereas the opposite pattern was observed in low oestradiol rats. However, the high apomorphine dose statistically significantly altered memory bias in high oestradiol rats from predominant place to predominant response memory, with a similar trend in the low apomorphine dose and the amphetamine group. There was no effect of drugs on memory bias in low oestradiol rats. Rats with high oestradiol replacement receiving amphetamine exhibited greater dorsal striatal dopamine release than low oestradiol replacement rats, and this difference was amplified in the right hemisphere. Furthermore, a logistic regression analysis revealed that oestradiol, but not dorsal striatal dopamine levels, significantly predicted response memory bias. These findings provide further evidence that oestradiol modulates memory system bias, and also that memory bias is changed by systemic apomorphine administration. However, although oestradiol affects dopamine transmission in the dorsal striatum in a lateralised manner, this does not predict memory system bias. PMID

  18. (R)-(5-tert-butyl-2,3-dihydro-1H-inden-1-yl)-3-(1H-indazol-4-yl)-urea (ABT-102) blocks polymodal activation of transient receptor potential vanilloid 1 receptors in vitro and heat-evoked firing of spinal dorsal horn neurons in vivo.

    PubMed

    Surowy, Carol S; Neelands, Torben R; Bianchi, Bruce R; McGaraughty, Steve; El Kouhen, Rachid; Han, Ping; Chu, Katharine L; McDonald, Heath A; Vos, Melissa; Niforatos, Wende; Bayburt, Erol K; Gomtsyan, Arthur; Lee, Chih-Hung; Honore, Prisca; Sullivan, James P; Jarvis, Michael F; Faltynek, Connie R

    2008-09-01

    The transient receptor potential vanilloid (TRPV) 1 receptor, a nonselective cation channel expressed on peripheral sensory neurons and in the central nervous system, plays a key role in pain. TRPV1 receptor antagonism is a promising approach for pain management. In this report, we describe the pharmacological and functional characteristics of a structurally novel TRPV1 antagonist, (R)-(5-tert-butyl-2,3-dihydro-1H-inden-1-yl)-3-(1H-indazol-4-yl)-urea (ABT-102), which has entered clinical trials. At the recombinant human TRPV1 receptor ABT-102 potently (IC(50) = 5-7 nM) inhibits agonist (capsaicin, N-arachidonyl dopamine, anandamide, and proton)-evoked increases in intracellular Ca(2+) levels. ABT-102 also potently (IC(50) = 1-16 nM) inhibits capsaicin-evoked currents in rat dorsal root ganglion (DRG) neurons and currents evoked through activation of recombinant rat TRPV1 currents by capsaicin, protons, or heat. ABT-102 is a competitive antagonist (pA(2) = 8.344) of capsaicin-evoked increased intracellular Ca(2+) and shows high selectivity for blocking TRPV1 receptors over other TRP receptors and a range of other receptors, ion channels, and transporters. In functional studies, ABT-102 blocks capsaicin-evoked calcitonin gene-related peptide release from rat DRG neurons. Intraplantar administration of ABT-102 blocks heat-evoked firing of wide dynamic range and nociceptive-specific neurons in the spinal cord dorsal horn of the rat. This effect is enhanced in a rat model of inflammatory pain induced by administration of complete Freund's adjuvant. Therefore, ABT-102 potently blocks multiple modes of TRPV1 receptor activation and effectively attenuates downstream consequences of receptor activity. ABT-102 is a novel and selective TRPV1 antagonist with pharmacological and functional properties that support its advancement into clinical studies. PMID:18515644

  19. Protein kinase C gamma-mediated phosphorylation of GluA1 in the postsynaptic density of spinal dorsal horn neurons accompanies neuropathic pain, and dephosphorylation by calcineurin is associated with prolonged analgesia.

    PubMed

    Miletic, Gordana; Hermes, Jessie L; Bosscher, Georgia L; Meier, Brenton M; Miletic, Vjekoslav

    2015-12-01

    Loss of calcineurin (protein phosphatase 3) activity and protein content in the postsynaptic density (PSD) of spinal dorsal horn neurons was associated with pain behavior after chronic constriction injury (CCI) of the rat sciatic nerve, and intrathecal administration of the phosphatase provided prolonged analgesia (Miletic et al. 2013). In this study, we examined whether one consequence of the loss of calcineurin was the persistent phosphorylation of the GluA1 subunit of α-amino-3-hydroxy-5-methyl-4-isoxazolepropioinic acid (AMPAR) receptors in the PSD. This would allow continual activation of AMPAR receptors at the synapse to help maintain a long-lasting enhancement of synaptic function, ie, neuropathic pain. We also investigated if the phosphorylation was mediated by protein kinase A (PKA), protein kinase C gamma (PKCγ), or calcium-calmodulin dependent kinase II (CaMKII), and if the prolonged calcineurin analgesia was associated with GluA1 dephosphorylation. Mechanical thresholds and thermal latencies were obtained before CCI. Seven days later, the behavioral testing was repeated before saline, calcineurin, or the specific peptide inhibitors of PKA (PKI-tide), PKCγ (PKC 19-31), or CaMKII (autocamtide-2-related inhibitory peptide) were injected intrathecally. The behavior was retested before the animals were euthanized and their PSD isolated. All CCI animals developed mechanical and thermal hypersensitivity. This was associated with phosphorylation of GluA1 in the ipsilateral PSD at Ser831 (but not Ser845) by PKCγ and not by PKA or CaMKII. Intrathecal treatment with calcineurin provided prolonged analgesia, and this was accompanied by GluA1 dephosphorylation. Therapy with calcineurin may prove useful in the prolonged clinical management of well-established neuropathic pain. PMID:26270583

  20. Activation of the dorsal hippocampal nicotinic acetylcholine receptors improves tamoxifen-induced memory retrieval impairment in adult female rats.

    PubMed

    Tajik, Azam; Rezayof, Ameneh; Ghasemzadeh, Zahra; Sardari, Maryam

    2016-07-01

    Tamoxifen (TAM), a selective estrogen receptor modulator, has frequently been used in the treatment of breast cancer. In view of the fact that cognitive deficits in women who receive adjuvant chemotherapy for breast cancer is a common health problem, using female animal models for investigating the cognitive effects of TAM administration may improve our knowledge of TAM therapy. Therefore, the present study assessed the role of dorsal hippocampal cholinergic nicotinic receptors (nAChRs) in the effect of TAM administration on memory retrieval in ovariectomized (OVX) and non-OVX female rats using a passive avoidance learning task. Our results showed that pre-test administration of TAM (2-6mg/kg) impaired memory retrieval. Pre-test intra-CA1 microinjection of nicotine (0.3-0.5μg/rat) reversed TAM-induced memory impairment. Pre-test intra-CA1 microinjection of mecamylamine (0.1-0.3μg/rat) plus 2mg/kg (an ineffective dose) of TAM impaired memory retrieval. Pre-test intra-CA1 microinjection of the same doses of nicotine and mecamylamine by themselves had no effect on memory retrieval. In OVX rats, the administration of TAM (6mg/kg) produced memory impairment but pre-test intra-CA1 microinjection of nicotine (0.5μg/rat) had no effect on TAM response. Moreover, the administration of an ineffective dose of TAM (2mg/kg) had no effect on memory retrieval in OVX rats, while pre-test intra-CA1 microinjection of mecamylamine (0.3μg/rat) impaired memory retrieval. Taken together, it can be concluded that the impairing effect of TAM on memory formation may be modulated by nAChRs of the CA1 regions. It seems that memory impairment may be considered as an important side effect of TAM. PMID:27072849

  1. Serotonin₆ receptors in the dorsal hippocampus regulate depressive-like behaviors in unilateral 6-hydroxydopamine-lesioned Parkinson's rats.

    PubMed

    Liu, Kun-Cheng; Li, Jun-Yi; Tan, Hui-Hui; Du, Cheng-Xue; Xie, Wen; Zhang, Yu-Ming; Ma, Wei-Lin; Zhang, Li

    2015-08-01

    Preclinical studies indicate both activation and blockade of serotonin6 (5-HT6) receptors may produce antidepressant-like effects. Depression is a common symptom in Parkinson's disease (PD); however, its pathophysiology is unclear. Here we examined whether 5-HT6 receptors in the dorsal hippocampus (DH) involve in the regulation of PD-associated depression. Unilateral 6-hydroxydopamine lesions of the medial forebrain bundle in rats induced depressive-like responses as measured by the sucrose preference and forced swim tests when compared to sham-operated rats. In sham-operated rats, intra-DH injection of 5HT6 receptor agonist WAY208466 or antagonist SB258585 increased sucrose consumption and decreased immobility time, indicating the induction of antidepressant effects. In the lesioned rats, WAY208466 also produced antidepressant effects, whereas SB258585 decreased sucrose consumption and increased immobility time, indicating the induction of depressive-like behaviors. Neurochemical results showed that WAY208466 did not change dopamine (DA) levels in the medial prefrontal cortex (mPFC), DH and habenula, and noradrenaline (NA) levels in the DH and habenula in sham-operated rats, and SB258585 increased DA and NA levels in these structures. Further, WAY208466 increased DA levels in the mPFC, DH and habenula, and NA level in the habenula in the lesioned rats, and SB258585 decreased DA levels in the mPFC and habenula. Additionally, the lesion did not change the density of neuronal glutamate transporter EAAC1/5-HT6 receptor co-expressing neurons in the DH. Compared to sham-operated rats, these findings suggest that the effects of 5-HT6 receptors in PD-associated depression may be mediated through different neurochemical mechanisms, and the DH is an important site involved in these effects. PMID:25863121

  2. cAMP stimulates the ubiquitin/proteasome pathway in rat spinal cord neurons.

    PubMed

    Myeku, Natura; Wang, Hu; Figueiredo-Pereira, Maria E

    2012-10-11

    Proteasome impairment and accumulation of ubiquitinated proteins are implicated in neurodegeneration associated with different forms of spinal cord injury. We show herein that elevating cAMP in rat spinal cord neurons increases 26S proteasome activity in a protein kinase A-dependent manner. Treating spinal cord neurons with dibutyryl-cAMP (db-cAMP) also raised the levels of various components of the UPP including proteasome subunits Rpt6 and β5, polyubiquitin shuttling factor p62/sequestosome1, E3 ligase CHIP, AAA-ATPase p97 and the ubiquitin gene ubB. Finally, db-cAMP reduced the accumulation of ubiquitinated proteins, proteasome inhibition, and neurotoxicity triggered by the endogenous product of inflammation prostaglandin J2. We propose that optimizing the effects of cAMP/PKA-signaling on the UPP could offer an effective therapeutic approach to prevent UPP-related proteotoxicity in spinal cord neurons. PMID:22982149

  3. Mondia whitei (Periplocaceae) prevents and Guibourtia tessmannii (Caesalpiniaceae) facilitates fictive ejaculation in spinal male rats

    PubMed Central

    2013-01-01

    Background Mondia whitei and Guibourtia tessmannii are used in Cameroon traditional medicine as aphrodisiacs. The present study was undertaken to evaluate the pro-ejaculatory effects of the aqueous and organic solvent extracts of these plants in spinal male rats. Methods In spinal cord transected and urethane-anesthetized rats, two electrodes where inserted into the bulbospongiosus muscles and the ejaculatory motor pattern was recorded on a polygraph after urethral and penile stimulations, intravenous injection of saline (0.1 ml/100 g), dopamine (0.1 μM/kg), aqueous and organic solvent plant extracts (20 mg/kg). Results In all spinal rats, urethral and penile stimulations always induced the ejaculatory motor pattern. Aqueous or hexane extract of Mondia whitei (20 mg/kg) prevented the expression of the ejaculatory motor pattern. The pro-ejaculatory effects of dopamine (0.1 μM/kg) were not abolished in spinal rats pre-treated with Mondia whitei extracts. Aqueous and methanolic stem bark extracts of Guibourtia tessmannii (20 mg/kg) induced fictive ejaculation characterized by rhythmic contractions of the bulbospongiosus muscles followed sometimes with expulsion of seminal plugs. In rats pre-treated with haloperidol (0.26 μM/kg), no ejaculatory motor pattern was recorded after intravenous injection of Guibourtia tessmannii extracts (20 mg/kg). Conclusion These results show that Mondia whitei possesses preventive effects on the expression of fictive ejaculation in spinal male rats, which is not mediated through dopaminergic pathway; on the contrary, the pro-ejaculatory activities of Guibourtia tessmannii require the integrity of dopaminergic system to exert its effects. The present findings further justify the ethno-medicinal claims of Mondia whitei and Guibourtia tessmannii. PMID:23295154

  4. Spinal cord influences on the colonic myoelectrical activity of fed and fasted rats.

    PubMed Central

    Du, C; Ferré, J P; Ruckebusch, Y

    1987-01-01

    1. The myoelectrical activity of the large intestine of fed and fasted rats was recorded with chronically implanted nichrome wire electrodes after destruction of the spinal cord, after spinal cord transection, and after spinal anaesthesia. 2. After spinal cord ablation, the cyclical organization of the colonic electrical spiking activity, as well as the gastrocolic reflex and accompanying postprandial enhancement of the cyclical pattern of activity, persisted on the proximal and distal colon. On the transverse colon, however, the spiking activity was considerably increased. This latter effect obliterated the gastrocolic response due to feeding but not the subsequent postprandial enhancement of the cyclical pattern of activity. 3. After spinal cord transection, the level of spiking activity also increased on both the transverse and distal colon, but no major changes in cyclical activity or in postprandial responses were recorded. 4. Spinal anaesthesia produced by intrathecal lidocaine increased the motility of the transverse colon to a level which masked the gastrocolic reflex. 5. These results suggest a prevertebral ganglia and/or a local control mechanism for the cyclical organization of the spiking activity of the colon. The central control mechanisms involve mostly spinal inhibitory influences on the transverse colon and supraspinal inhibitory influences on the distal colon. PMID:3656127

  5. Three-dimensional imaging of microvasculature in the rat spinal cord following injury

    PubMed Central

    Cao, Yong; Wu, Tianding; yuan, Zhou; Li, Dongzhe; Ni, Shuangfei; Hu, Jianzhong; Lu, Hongbin

    2015-01-01

    Research studies on the three-dimensional (3D) morphological alterations of the spinal cord microvasculature after injury provide insight into the pathology of spinal cord injury (SCI). Knowledge in this field has been hampered in the past by imaging technologies that provided only two-dimensional (2D) information on the vascular reactions to trauma. The aim of our study is to investigate the 3D microstructural changes of the rat spinal cord microvasculature on day 1 post-injury using synchrotron radiation micro-tomography (SRμCT). This technology provides high-resolution 3D images of microvasculature in both normal and injured spinal cords, and the smallest vessel detected is approximately 7.4 μm. Moreover, we optimized the 3D vascular visualization with color coding and accurately calculated quantitative changes in vascular architecture after SCI. Compared to the control spinal cord, the damaged spinal cord vessel numbers decreased significantly following injury. Furthermore, the area of injury did not remain concentrated at the epicenter; rather, the signs of damage expanded rostrally and caudally along the spinal cord in 3D. The observed pathological changes were also confirmed by histological tests. These results demonstrate that SRμCT is an effective technology platform for imaging pathological changes in small arteries in neurovascular disease and for evaluating therapeutic interventions. PMID:26220842

  6. Kinetic analysis of two types of Na+ channels in rat dorsal root ganglia.

    PubMed Central

    Ogata, N; Tatebayashi, H

    1993-01-01

    1. The gating properties of two types of Na+ channels were studied in neurones isolated from rat dorsal root ganglia using the whole cell variation of the patch electrode voltage-clamp technique. 2. Two types of Na+ currents (INa) were identified on the basis of their sensitivity to tetrodotoxin (TTX). One type was insensitive to TTX (up to 0.1 mM), while the other type was blocked by 1 nM of TTX. Whereas they were both insensitive to 50 microM Cd2+, a high concentration (2 mM) of Co2+ selectively inhibited the TTX-insensitive type. 3. The activation thresholds were about -60 and -40 mV for the TTX-sensitive and the TTX-insensitive INa, respectively. Activation of the TTX-sensitive INa developed with a sigmoidal time course which was described by m3 kinetics, whereas the activation of the TTX-insensitive INa was described by a single exponential function. A deactivation process, as measured by the tail current upon repolarization, followed an exponential decay in either type of INa. 4. The rate constant of activation indicated that under comparable membrane potential conditions, the TTX-insensitive channels open 4-5 times slower than the TTX-sensitive ones upon depolarization. Likewise, the rate constant of inactivation indicated that the TTX-insensitive channels inactivate 3-7 times more slowly than the TTX-sensitive ones upon repolarization. 5. The steady-state activation curve for the TTX-insensitive INa was shifted about 20 mV in the positive direction from that for the TTX-sensitive INa. 6. The steady-state inactivation curve for the TTX-insensitive INa as obtained with a 0.5 s prepulse was shifted about 26 mV in the positive direction from that for the TTX-sensitive INa, indicating a greater availability for the TTX-insensitive INa in depolarized membrane. However, on increasing the duration of prepulse, the inactivation curve for the TTX-insensitive INa, but not for the TTX-sensitive INa, shifted in the negative direction due to an extremely slow

  7. Activation of the trigeminal medullary dorsal horn during voluntary diving in rats.

    PubMed

    McCulloch, Paul F

    2005-07-27

    Fos immunohistochemistry was used to indicate whether activation of trigeminal neurons occurs in voluntarily diving rats. In rats trained to dive underwater, significant increases in Fos labeling were found within the ventral superficial MDH and paratrigeminal nucleus, 100-150 microm caudal to the obex compared to control rats. The conclusion is that the ventral superficial MDH is the initial brainstem afferent relay of diving response in voluntarily diving rats. PMID:15978555

  8. Functional Electrical Stimulation Helps Replenish Progenitor Cells in the Injured Spinal Cord of Adult Rats

    PubMed Central

    Becker, Daniel; Gary, Devin S.; Rosenzweig, Ephron S.; Grill, Warren M.; McDonald, John W.

    2010-01-01

    Functional electrical stimulation (FES) can restore control and offset atrophy to muscles after neurological injury. However, FES has not been considered as a method for enhancing CNS regeneration. This paper demonstrates that FES dramatically enhanced progenitor cell birth in the spinal cord of rats with a chronic spinal cord injury (SCI). A complete SCI at thoracic level 8/9 was performed on 12 rats. Three weeks later, a FES device to stimulate hindlimb movement was implanted into these rats. Twelve identically-injured rats received inactive FES implants. An additional control group of uninjured rats were also examined. Ten days after FES implantation, dividing cells were marked with bromodeoxyuridine (BrdU). The ‘cell birth’ subgroup (half the animals in each group) was sacrificed immediately after completion of BrdU administration, and the ‘cell survival’ subgroup was sacrificed 7 days later. In the injured ‘cell birth’ subgroup, FES induced an 82-86 % increase in cell birth in the lumbar spinal cord. In the injured ‘cell survival’ subgroup, the increased lumbar newborn cell counts persisted. FES doubled the proportion of the newly-born cells which expressed nestin and other markers suggestive of tripotential progenitors. In uninjured rats, FES had no effect on cell birth/survival. This report suggests that controlled electrical activation of the CNS may enhance spontaneous regeneration after neurological injuries. PMID:20059998

  9. Overexpression of GRK6 attenuates neuropathic pain via suppression of CXCR2 in rat dorsal root ganglion.

    PubMed

    Zhou, Yuan; Li, Rong-Ji; Li, Meng; Liu, Xuelian; Zhu, Hong-Yan; Ju, Zhong; Miao, Xiuhua; Xu, Guang-Yin

    2016-01-01

    G protein-coupled kinase (GRK) 6 is a member of the GRK family that mediates agonist-induced desensitization and signaling of G protein-coupled receptors (GPCRs), thus involving in a wide variety of processes including inflammation and nociception. Recent studies have indicated that chemokines play an important role in chronic pain via increased expression of respective GPCRs. This study was designed to investigate the role of GRK6 and its interaction with substrate chemokine receptors in dorsal root ganglion (DRG) in a rat model of neuropathic pain induced by chronic constriction injury (CCI). Following induction of CCI, GRK6 expression was significantly downregulated in rat DRGs at L4-L6 segments. Overexpression of GRK6 using lentiviral-mediated production strategy via sciatic nerve injection markedly attenuated mechanical allodynia and thermal hyperalgesia in CCI rats. Overexpression of GRK6 also drastically reversed the hyperexcitability of DRG neurons innervating the hind paw and suppressed the enhanced expression of CXCR2 in DRGs of CCI rats. In addition, co-immunoprecipitation, immunofluorescence, and correlation analysis supported the interaction between GRK6 and CXCR2. These results suggest that GRK6 might be a key molecular involved in peripheral mechanism of neuropathic pain and that overexpression of GRK6 might be a potential strategy for treatment for neuropathic pain through inhibition of CXCR2 signal pathway. PMID:27145805

  10. Overexpression of GRK6 attenuates neuropathic pain via suppression of CXCR2 in rat dorsal root ganglion

    PubMed Central

    Zhou, Yuan; Li, Rong-Ji; Li, Meng; Liu, Xuelian; Zhu, Hong-Yan; Ju, Zhong; Miao, Xiuhua

    2016-01-01

    G protein-coupled kinase (GRK) 6 is a member of the GRK family that mediates agonist-induced desensitization and signaling of G protein-coupled receptors (GPCRs), thus involving in a wide variety of processes including inflammation and nociception. Recent studies have indicated that chemokines play an important role in chronic pain via increased expression of respective GPCRs. This study was designed to investigate the role of GRK6 and its interaction with substrate chemokine receptors in dorsal root ganglion (DRG) in a rat model of neuropathic pain induced by chronic constriction injury (CCI). Following induction of CCI, GRK6 expression was significantly downregulated in rat DRGs at L4-L6 segments. Overexpression of GRK6 using lentiviral-mediated production strategy via sciatic nerve injection markedly attenuated mechanical allodynia and thermal hyperalgesia in CCI rats. Overexpression of GRK6 also drastically reversed the hyperexcitability of DRG neurons innervating the hind paw and suppressed the enhanced expression of CXCR2 in DRGs of CCI rats. In addition, co-immunoprecipitation, immunofluorescence, and correlation analysis supported the interaction between GRK6 and CXCR2. These results suggest that GRK6 might be a key molecular involved in peripheral mechanism of neuropathic pain and that overexpression of GRK6 might be a potential strategy for treatment for neuropathic pain through inhibition of CXCR2 signal pathway. PMID:27145805

  11. Exogenous brain-derived neurotrophic factor relieves pain symptoms of diabetic rats by reducing excitability of dorsal root ganglion neurons.

    PubMed

    Li, Lei; Yu, Ting; Yu, Liling; Li, Haijun; Liu, Yongjuan; Wang, Dongqin

    2016-08-01

    Diabetic peripheral neuropathy (DPN) is a common complication of diabetes lacking of effective treatments. Enhanced excitability of dorsal root ganglion (DRG) neuron plays a crucial role in the progression of diabetic neuropathic hyperalgesia. Brain-derived neurotrophic factor (BDNF) is known as a neuromodulator of nociception, but whether and how BDNF modulates the excitability of DRG neurons in the development of DPN remain to be clarified. This study investigated the role of exogenous BDNF and its high-affinity tropomyosin receptor kinase B (TrkB) in rats with streptozotocin-induced diabetic neuropathic pain. The results showed that continued intrathecal administration of BDNF to diabetic rats dramatically alleviated mechanical and thermal hyperalgesia, as well as inhibited hyperexcitability of DRG neurons. These effects were blocked by pretreatment with TrkB Fc (a synthetic fusion protein consisting of the extracellular ligand-binding domain of the TrkB receptor). The expression of BDNF and TrkB was upregulated in the DRG of diabetic rats. Intrathecal administration of BDNF did not affect this upregulation. These data provide novel information that exogenous BDNF relieved pain symptoms of diabetic rats by reducing hyperexcitability of DRG neurons and might be the potential treatment of painful diabetic neuropathy. PMID:26441011

  12. Influence of Sexuality in Functional Recovery after Spinal Cord Injury in Rats

    PubMed Central

    Emamhadi, Mohammadreza; Soltani, Bahram; Babaei, Parvin; Mashhadinezhad, Hossein; Ghadarjani, Shervin

    2016-01-01

    Background: Spinal cord injury (SCI) is a major clinical condition and research is commonly done to find suitable treatment options. However, there are some degrees of spontaneous recovery after SCI and gender is said to be a contributing factor in recovery, but this is controversial. This study was done to compare the effects of sexual dimorphism on spontaneous recovery after spinal cord injury in Wistar Rats. Methods: Spinal cord lesions were made by compressing the cord at T9 level and making a spinal cord contusion. Routine care of each rat was done daily. The LSS scoring system was used to measure the locomotion of these rats and to compare the recovery rate between male and female rats. Results: The results suggested that there was no significant difference between the two sex in recovery. Conclusions: To be female does not seem to be a prognostic factor for recovery after SCI. However, this preliminary study should be repeated in other animals and in larger cohorts. PMID:26894220

  13. Age-Related Differences in Neuropathic Pain Behavior and Spinal Microglial Activity after L5 Spinal Nerve Ligation in Male Rats

    PubMed Central

    Zeinali, Hossein; Manaheji, Homa; Zaringhalam, Jalal; Bahari, Zahra; Nazemi, Samad; Sadeghi, Mehdi

    2016-01-01

    Introduction: Several studies have reported the involvement of age-related changes in the development of neuropathic pain behaviors. However, limited data are available on the role of age in establishing and maintaining chronic neuropathic pain after peripheral nerve injury. Methods: In the present study, we examined age-related neuropathic behavior among rats in 4 age groups: pups (4 weeks old; weight, 60–80 g), juvenile rats (6 weeks old; weight, 120–140 g), and mature rats (10–12 weeks old; weight, 200–250 g). Because the exact contribution of spinal microglia and its association with the development of neuropathic pain remains unknown, we also evaluated the expression of spinal Iba1, a microglial marker, by using western blotting before and 5 days after spinal nerve ligation (SNL) as well as after the daily IP administration of minocycline (30 mg/kg). Results: Our results showed that SNL-induced mechanical allodynia but not thermal hyperalgesia in mature rats but not in pups (P<0.05 and P<0.01, respectively). The expression of spinal Iba1 in the juvenile rats was significantly lower than that in pups and mature rats (P<0.01). Moreover, administration of minocycline decreased the expression of spinal Iba1 in the pup rats more than in juvenile rats (P<0.001) and in the juvenile rats more than in the mature rats (P<0.05). Conclusion: These data suggest that the development of neuropathic behaviors and microglial activation after SNL could be age dependent. PMID:27563413

  14. Phosphorylation of CaMKII in the rat dorsal raphe nucleus plays an important role in sleep-wake regulation.

    PubMed

    Cui, Su-Ying; Li, Sheng-Jie; Cui, Xiang-Yu; Zhang, Xue-Qiong; Yu, Bin; Sheng, Zhao-Fu; Huang, Yuan-Li; Cao, Qing; Xu, Ya-Ping; Lin, Zhi-Ge; Yang, Guang; Song, Jin-Zhi; Ding, Hui; Wang, Zi-Jun; Zhang, Yong-He

    2016-02-01

    The Ca(2+) modulation in the dorsal raphe nucleus (DRN) plays an important role in sleep-wake regulation. Calmodulin-dependent kinase II (CaMKII) is an important signal-transducing molecule that is activated by Ca(2+) . This study investigated the effects of intracellular Ca(2+) /CaMKII signaling in the DRN on sleep-wake states in rats. Maximum and minimum CaMKII phosphorylation was detected at Zeitgeber time 21 (ZT 21; wakefulness state) and ZT 3 (sleep state), respectively, across the light-dark rhythm in the DRN in rats. Six-hour sleep deprivation significantly reduced CaMKII phosphorylation in the DRN. Microinjection of the CAMKII activation inhibitor KN-93 (5 or 10 nmol) into the DRN suppressed wakefulness and enhanced rapid-eye-movement sleep (REMS) and non-REM sleep (NREMS). Application of a high dose of KN-93 (10 nmol) increased slow-wave sleep (SWS) time, SWS bouts, the mean duration of SWS, the percentage of SWS relative to total sleep, and delta power density during NREMS. Microinjection of CaCl2 (50 nmol) in the DRN increased CaMKII phosphorylation and decreased NREMS, SWS, and REMS. KN-93 abolished the inhibitory effects of CaCl2 on NREMS, SWS, and REMS. These data indicate a novel wake-promoting and sleep-suppressing role for the Ca(2+) /CaMKII signaling pathway in DRN neurons. We propose that the intracellular Ca(2+) /CaMKII signaling in the dorsal raphe nucleus (DRN) plays wake-promoting and sleep-suppressing role in rats. Intra-DRN application of KN-93 (CaMKII activation inhibitor) suppressed wakefulness and enhanced rapid-eye-movement sleep (REMS) and non-REMS (NREMS). Intra-DRN application of CaCl2 attenuated REMS and NREMS. We think these findings should provide a novel cellular and molecular mechanism of sleep-wake regulation. PMID:26558357

  15. Proteomic analysis of the dorsal and ventral hippocampus of rats maintained on a high fat and refined sugar diet.

    PubMed

    Francis, Heather M; Mirzaei, Mehdi; Pardey, Margery C; Haynes, Paul A; Cornish, Jennifer L

    2013-10-01

    The typical Western diet, rich in high saturated fat and refined sugar (HFS), has been shown to increase cognitive decline with aging and Alzheimer's disease, and to affect cognitive functions that are dependent on the hippocampus, including memory processes and reversal learning. To investigate neurophysiological changes underlying these impairments, we employed a proteomic approach to identify differentially expressed proteins in the rat dorsal and ventral hippocampus following maintenance on an HFS diet. Rats maintained on the HFS diet for 8 weeks were impaired on a novel object recognition task that assesses memory and on a Morris Water Maze task assessing reversal learning. Quantitative label-free shotgun proteomic analysis was conducted on biological triplicates for each group. For the dorsal hippocampus, 59 proteins were upregulated and 36 downregulated in the HFS group compared to controls. Pathway ana-lysis revealed changes to proteins involved in molecular transport and cellular and molecular signaling, and changes to signaling pathways including calcium signaling, citrate cycle, and oxidative phosphorylation. For the ventral hippocampus, 25 proteins were upregulated and 27 downregulated in HFS fed rats. Differentially expressed proteins were involved in cell-to-cell signaling and interaction, and cellular and molecular function. Changes to signaling pathways included protein ubiquitination, ubiquinone biosynthesis, oxidative phosphorylation, and mitochondrial dysfunction. This is the first shotgun proteomics study to examine protein changes in the hippocampus following long-term consumption of a HFS diet, identifying changes to a large number of proteins including those involved in synaptic plasticity and energy metabolism. All MS data have been deposited in the ProteomeXchange with identifier PXD000028. PMID:23963966

  16. Supraspinal morphine and descending inhibitions acting on the dorsal horn of the rat.

    PubMed Central

    Dickenson, A H; Le Bars, D

    1987-01-01

    1. Recordings were made from thirty-nine convergent neurones in the lumbar enlargement of the rat spinal cord. These neurones were activated by both innocuous and noxious stimuli applied to their excitatory receptive fields located on the extremity of the ipsilateral hind paw. Transcutaneous application of suprathreshold 2 ms square-wave pulses to the centre of the receptive field resulted in responses to A- and C-fibre activation being observed; a mean of 18.8 +/- 1.8 C-fibre latency spikes was evoked per stimulus. This type of response was inhibited by applying noxious conditioning stimuli to heterotopic body areas; immersing the tail in a 52 degrees C water-bath caused a mean 54.5 +/- 2.3% inhibition of the C-fibre-evoked response; such inhibitory processes have been termed diffuse noxious inhibitory controls (d.n.i.c.). 2. The effects of microinjections of morphine (5 micrograms; 0.2 microliter) on both the unconditioned C-fibre-evoked response and inhibitory processes triggered from the tail were investigated in an attempt to answer two questions: (a) does morphine increase tonic descending inhibitory processes and (b) what are the effects of morphine on descending inhibitory processes triggered by noxious stimuli? 3. The predominant effect of periaqueductal grey matter (p.a.g.) morphine on the C-fibre-evoked responses was a facilitation: 51% of cells had their C-fibre-evoked responses increased by morphine (by roughly 50%); 31% of cells were not influenced while the remaining 18% of units were depressed; however the cells classified as depressed were only marginally so. No clear relationships were found either between the microinjection sites in the p.a.g. and their corresponding effects or between the number of C-fibre-spikes evoked in the control sequences and the subsequent effect of morphine. 4. While d.n.i.c. was not altered by morphine in 56% of cases, it was clearly reduced in the remaining cells. The effects were immediate but peaked at 40 min

  17. Delayed Exercise Is Ineffective at Reversing Aberrant Nociceptive Afferent Plasticity or Neuropathic Pain After Spinal Cord Injury in Rats.

    PubMed

    Detloff, Megan Ryan; Quiros-Molina, Daniel; Javia, Amy S; Daggubati, Lekhaj; Nehlsen, Anthony D; Naqvi, Ali; Ninan, Vinu; Vannix, Kirsten N; McMullen, Mary-Katharine; Amin, Sheena; Ganzer, Patrick D; Houlé, John D

    2016-08-01

    Neuropathic pain is a debilitating consequence of spinal cord injury (SCI) that correlates with sensory fiber sprouting. Recent data indicate that exercise initiated early after SCI prevents the development of allodynia and modulated nociceptive afferent plasticity. This study determined if delaying exercise intervention until pain is detected would similarly ameliorate established SCI-induced pain. Adult, female Sprague-Dawley rats with a C5 unilateral contusion were separated into SCI allodynic and SCI non-allodynic cohorts at 14 or 28 days postinjury when half of each group began exercising on automated running wheels. Allodynia, assessed by von Frey testing, was not ameliorated by exercise. Furthermore, rats that began exercise with no allodynia developed paw hypersensitivity within 2 weeks. At the initiation of exercise, the SCI Allodynia group displayed marked overlap of peptidergic and non-peptidergic nociceptive afferents in the C7 and L5 dorsal horn, while the SCI No Allodynia group had scant overlap. At the end of 5 weeks of exercise both the SCI Allodynia and SCI No Allodynia groups had extensive overlap of the 2 c-fiber types. Our findings show that exercise therapy initiated at early stages of allodynia is ineffective at attenuating neuropathic pain, but rather that it induces allodynia-aberrant afferent plasticity in previously pain-free rats. These data, combined with our previous results, suggest that there is a critical therapeutic window when exercise therapy may be effective at treating SCI-induced allodynia and that there are postinjury periods when exercise can be deleterious. PMID:26671215

  18. Minocycline attenuates bone cancer pain in rats by inhibiting NF-κB in spinal astrocytes

    PubMed Central

    Song, Zhen-peng; Xiong, Bing-rui; Guan, Xue-hai; Cao, Fei; Manyande, Anne; Zhou, Ya-qun; Zheng, Hua; Tian, Yu-ke

    2016-01-01

    Aim: To investigate the mechanisms underlying the anti-nociceptive effect of minocycline on bone cancer pain (BCP) in rats. Methods: A rat model of BCP was established by inoculating Walker 256 mammary carcinoma cells into tibial medullary canal. Two weeks later, the rats were injected with minocycline (50, 100 μg, intrathecally; or 40, 80 mg/kg, ip) twice daily for 3 consecutive days. Mechanical paw withdrawal threshold (PWT) was used to assess pain behavior. After the rats were euthanized, spinal cords were harvested for immunoblotting analyses. The effects of minocycline on NF-κB activation were also examined in primary rat astrocytes stimulated with IL-1β in vitro. Results: BCP rats had marked bone destruction, and showed mechanical tactile allodynia on d 7 and d 14 after the operation. Intrathecal injection of minocycline (100 μg) or intraperitoneal injection of minocycline (80 mg/kg) reversed BCP-induced mechanical tactile allodynia. Furthermore, intraperitoneal injection of minocycline (80 mg/kg) reversed BCP-induced upregulation of GFAP (astrocyte marker) and PSD95 in spinal cord. Moreover, intraperitoneal injection of minocycline (80 mg/kg) reversed BCP-induced upregulation of NF-κB, p-IKKα and IκBα in spinal cord. In IL-1β-stimulated primary rat astrocytes, pretreatment with minocycline (75, 100 μmol/L) significantly inhibited the translocation of NF-κB to nucleus. Conclusion: Minocycline effectively alleviates BCP by inhibiting the NF-κB signaling pathway in spinal astrocytes. PMID:27157092

  19. Altered differentiation of CNS neural progenitor cells after transplantation into the injured adult rat spinal cord.

    PubMed

    Onifer, S M; Cannon, A B; Whittemore, S R

    1997-01-01

    Denervation of CNS neurons and peripheral organs is a consequence of traumatic SCI. Intraspinal transplantation of embryonic CNS neurons is a potential strategy for reinnervating these targets. Neural progenitor cell lines are being investigated as alternates to embryonic CNS neurons. RN33B is an immortalized neural progenitor cell line derived from embryonic rat raphe nuclei following infection with a retrovirus encoding the temperature-sensitive mutant of SV40 large T-antigen. Transplantation studies have shown that local epigenetic signals in intact or partially neuron-depleted adult rat hippocampal formation or striatum direct RN33B cell differentiation to complex multipolar morphologies resembling endogenous neurons. After transplantation into neuron-depleted regions of the hippocampal formation or striatum, RN33B cells were relatively undifferentiated or differentiated with bipolar morphologies. The present study examines RN33B cell differentiation after transplantation into normal spinal cord and under different lesion conditions. Adult rats underwent either unilateral lesion of lumbar spinal neurons by intraspinal injection of kainic acid or complete transection at the T10 spinal segment. Neonatal rats underwent either unilateral lesion of lumbar motoneurons by sciatic nerve crush or complete transection at the T10 segment. At 2 or 6-7 wk postinjury, lacZ-labeled RN33B cells were transplanted into the lumbar enlargement of injured and age-matched normal rats. At 2 wk posttransplantation, bipolar and some multipolar RN33B cells were found throughout normal rat gray matter. In contrast, only bipolar RN33B cells were seen in gray matter of kainic acid lesioned, sciatic nerve crush, or transection rats. These observations suggest that RN33B cell multipolar morphological differentiation in normal adult spinal cord is mediated by direct cell-cell interaction through surface molecules on endogenous neurons and may be suppressed by molecules released after SCI

  20. Differential effects of low versus high amounts of weight supported treadmill training in spinally transected rats.

    PubMed

    de Leon, Ray D; See, Pamela A; Chow, Cheryl H T

    2011-06-01

    Intensive weight-supported treadmill training (WSTT) improves locomotor function following spinal cord injury. Because of a number of factors, undergoing intensive sessions of training may not be feasible. Whether reduced amounts of training are sufficient to enhance spinal plasticity to a level that is necessary for improving function is not known. The focus of the present study was to assess differences in recovery of locomotor function and spinal plasticity as a function of the amount of steps taken during WSTT in a rodent model of spinal cord injury. Rats were spinally transected at 5 days of age. When they reached 28 days of age, a robotic system was used to implement a weight-supported treadmill training program of either 100 or 1000 steps/training session daily for 4 weeks. Antibodies for brain-derived neurotrophic factor (BDNF), TrkB, and the pre-synaptic marker, synaptophysin, were used to examine the expression of these proteins in the ventral horn of the lumbar spinal cord. Rats that received weight-supported treadmill training performed better stepping relative to untrained rats, but only the rats that received 1000 steps/training session recovered locomotor function that resembled normal patterns. Only the rats that received 1000 steps/training session recovered normal levels of synaptophysin immunoreactivity around motor neurons. Weight-supported treadmill training consisting of either 100 or 1000 steps/training session increased BDNF immunoreactivity in the ventral horn of the lumbar spinal cord. TrkB expression in the ventral horn was not affected by spinal cord transection or weight-supported treadmill training. Synaptophysin expression, but not BDNF or TrkB expression was correlated with the recovery of stepping function. These findings suggested that a large amount of weight-supported treadmill training was necessary for restoring synaptic connections to motor neurons within the locomotor generating circuitry. Although a large amount of training

  1. Comparison of polymer scaffolds in rat spinal cord: A step toward quantitative assessment of combinatorial approaches to spinal cord repair

    PubMed Central

    Chen, Bingkun K.; Knight, Andrew M.; Madigan, Nicolas N.; Gross, LouAnn; Dadsetan, Mahrokh; Nesbitt, Jarred J; Rooney, Gemma E.; Currier, Bradford L.; Yaszemski, Michael J.; Spinner, Robert J.; Windebank, Anthony J.

    2011-01-01

    The transected rat thoracic (T9/10) spinal cord model is a platform for quantitatively compa0ring biodegradable polymer scaffolds. Schwann cell-loaded scaffolds constructed from poly (lactic co-glycolic acid) (PLGA), poly(ε-caprolactone fumarate) (PCLF), oligo(polyethylene glycol) fumarate (OPF) hydrogel or positively charged OPF (OPF+) hydrogel were implanted into the model. We demonstrated that the mechanical properties (3-point bending and stiffness) of OPF and OPF+ hydrogels closely resembled rat spinal cord. After one month, tissues were harvested and analyzed by morphometry of neurofilament-stained sections at rostral, midlevel, and caudal scaffold. All polymers supported axonal growth. Significantly higher numbers of axons were found in PCLF (P < 0.01) and OPF+ (P < 0.05) groups, compared to that of the PLGA group. OPF+ polymers showed more centrally distributed axonal regeneration within the channels while other polymers (PLGA, PCLF and OPF) tended to show more evenly dispersed axons within the channels. The centralized distribution was associated with significantly more axons regenerating (P < 0.05). Volume of scar and cyst rostral and caudal to the implanted scaffold was measured and compared. There were significantly smaller cyst volumes in PLGA compared to PCLF groups. The model provides a quantitative basis for assessing individual and combined tissue engineering strategies. PMID:21803415

  2. Immunostaining of rat brain, spinal cord, sensory neurons and skeletal muscle for calcium channel alpha2-delta (alpha2-delta) type 1 protein.

    PubMed

    Taylor, C P; Garrido, R

    2008-08-13

    Alpha2-delta (alpha2-delta) is a membrane-spanning auxiliary protein subunit of voltage-gated calcium channels found in muscle and brain. Of the four subtypes of alpha2-delta, only alpha2-delta types 1 and 2 (alpha2-delta-1 and alpha2-delta-2) bind the drugs gabapentin (Neurontin) and pregabalin (Lyrica). Although recent findings indicate that drug binding to alpha2-delta-1 is required for pharmacology of pregabalin and gabapentin, previous work has not addressed the location of alpha2-delta-1 protein within nervous tissues. A monoclonal antibody to alpha2-delta-1 revealed intense immunostaining in certain areas of rat brain, spinal cord, dorsal root ganglia, and skeletal muscle, with weaker staining in heart muscle, gut and liver. Little immunostaining was seen in spleen, kidney, thymus and lung. Staining was dense in some regions of the CNS including spinal dorsal horn, anterior olfactory nucleus, anterior amygdala, basolateral (ventral) amygdala and cortical amygdala, and the piriform, perirhinal, insular and entorhinal cortices. In hippocampus, staining was heterogeneous with greater density in areas of glutamate terminals (mossy fiber endings on CA3 pyramidal cells and perforant path endings on granule cells and CA1 stratum radiatum). Moderate staining occurred in the lateral posterior nucleus of the thalamus, superficial layers of neocortex, periaqueductal gray, substantia nigra, stria terminalis, nucleus accumbens shell and tegmental nucleus. We propose that areas of dense alpha2-delta-1 staining in brain and spinal cord are likely sites of action for the analgesic, anticonvulsant and anxiolytic-like actions of pregabalin and gabapentin in animal models. PMID:18616987

  3. The anterior pretectal nucleus participates as a relay station in the glutamate-, but not morphine-induced antinociception from the dorsal raphe nucleus in rats.

    PubMed

    Prado, W A; Faganello, F A

    2000-11-01

    The anterior pretectal nucleus (APtN) and the dorsal raphe nucleus (DRN) are involved in descending pathways that control noxious inputs to the spinal cord and participate in the normal physiological response to noxious stimulation. Evidence has also been provided for the involvement of the APtN acting as a relay station through which the DRN partly modulates spinal nociceptive messages. In the present study, the effects of microinjecting glutamate or morphine into the DRN on the latency for the tail withdrawal reflex after noxious heating of the skin were examined in rats in which hyperbaric lidocaine (5%), naloxone (a non-selective opioid antagonist) or methiothepin (a non-selective 5-HT(1) antagonist) was previously microinjected into the APtN. Microinjection of glutamate (38 nmol/0.25 microl) into the DRN evoked strong but short-lasting antinociception that was fully inhibited by the previous administration of lidocaine (0.25 microl), naloxone (2.7 nmol/0.25 microl), or methiothepin (1 nmol/0.25 microl). A smaller dose of methiothepin (0.5 nmol/0.25 microl) significantly reduced the effect of glutamate. Microinjection of morphine (7.5 nmol/0.25 microl) into the DRN evoked strong and long-lasting antinociception that was not significantly changed by previous microinjection of lidocaine into the APtN. These results confirm that APtN integrity is at least in part necessary for the antinociceptive effects of stimulating the DRN, and that at least opioid and 5-HT1 mechanisms in the APtN participate as neuromodulators in the DRN-APtN connection. The results demonstrate that the antinociceptive effects of stimulating the DRN-APtN path depend on the activation of cell bodies in the DRN that can be excited by the local administration of glutamate, but not morphine. The study also further supports the notion that the DRN is involved in both descending and ascending pain inhibitory systems. PMID:11050372

  4. Effects of Tramadol on Substantia Gelatinosa Neurons in the Rat Spinal Cord: An In Vivo Patch-Clamp Analysis

    PubMed Central

    Yamasaki, Hiroyuki; Funai, Yusuke; Funao, Tomoharu; Mori, Takashi; Nishikawa, Kiyonobu

    2015-01-01

    Tramadol is thought to modulate synaptic transmissions in the spinal dorsal horn mainly by activating µ-opioid receptors and by inhibiting the reuptake of monoamines in the CNS. However, the precise mode of modulation remains unclear. We used an in vivo patch clamp technique in urethane-anesthetized rats to determine the antinociceptive mechanism of tramadol. In vivo whole-cell recordings of spontaneous inhibitory postsynaptic currents (sIPSCs) and spontaneous excitatory postsynaptic currents (sEPSCs) were made from substantia gelatinosa (SG) neurons (lamina II) at holding potentials of 0 mV and -70 mV, respectively. The effects of intravenous administration (0.5, 5, 15 mg/kg) of tramadol were evaluated. The effects of superfusion of tramadol on the surface of the spinal cord and of a tramadol metabolite (M1) were further analyzed. Intravenous administration of tramadol at doses >5 mg/kg decreased the sEPSCs and increased the sIPSCs in SG neurons. These effects were not observed following naloxone pretreatment. Tramadol superfusion at a clinically relevant concentration (10 µM) had no effect, but when administered at a very high concentration (100 µM), tramadol decreased sEPSCs, produced outward currents, and enhanced sIPSCs. The effects of M1 (1, 5 mg/kg intravenously) on sEPSCs and sIPSCs were similar to those of tramadol at a corresponding dose (5, 15 mg/kg). The present study demonstrated that systemically administered tramadol indirectly inhibited glutamatergic transmission, and enhanced GABAergic and glycinergic transmissions in SG neurons. These effects were mediated primarily by the activation of μ-opioid receptors. M1 may play a key role in the antinociceptive mechanisms of tramadol. PMID:25933213

  5. 5-HT1B receptors inhibit glutamate release from primary afferent terminals in rat medullary dorsal horn neurons

    PubMed Central

    Choi, I-S; Cho, J-H; An, C-H; Jung, J-K; Hur, Y-K; Choi, J-K; Jang, I-S

    2012-01-01

    BACKGROUND AND PURPOSE Although 5-HT1B receptors are expressed in trigeminal sensory neurons, it is still not known whether these receptors can modulate nociceptive transmission from primary afferents onto medullary dorsal horn neurons. EXPERIMENTAL APPROACH Primary afferent-evoked EPSCs were recorded from medullary dorsal horn neurons of rat horizontal brain stem slices using a conventional whole-cell patch clamp technique under a voltage-clamp condition. KEY RESULTS CP93129, a selective 5-HT1B receptor agonist, reversibly and concentration-dependently decreased the amplitude of glutamatergic EPSCs and increased the paired-pulse ratio. In addition, CP93129 reduced the frequency of spontaneous miniature EPSCs without affecting the current amplitude. The CP93129-induced inhibition of EPSCs was significantly occluded by GR55562, a 5-HT1B/1D receptor antagonist, but not LY310762, a 5-HT1D receptor antagonist. Sumatriptan, an anti-migraine drug, also decreased EPSC amplitude, and this effect was partially blocked by either GR55562 or LY310762. On the other hand, primary afferent-evoked EPSCs were mediated by the Ca2+ influx passing through both presynaptic N-type and P/Q-type Ca2+ channels. The CP93129-induced inhibition of EPSCs was significantly occluded by ω-conotoxin GVIA, an N-type Ca2+ channel blocker. CONCLUSIONS AND IMPLICATIONS The present results suggest that the activation of presynaptic 5-HT1B receptors reduces glutamate release from primary afferent terminals onto medullary dorsal horn neurons, and that 5-HT1B receptors could be, at the very least, a potential target for the treatment of pain from orofacial tissues. LINKED ARTICLE This article is commented on by Connor, pp. 353–355 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2012.01963.x PMID:22462474

  6. Forelimb EMG-based trigger to control an electronic spinal bridge to enable hindlimb stepping after a complete spinal cord lesion in rats

    PubMed Central

    2012-01-01

    Background A complete spinal cord transection results in loss of all supraspinal motor control below the level of the injury. The neural circuitry in the lumbosacral spinal cord, however, can generate locomotor patterns in the hindlimbs of rats and cats with the aid of motor training, epidural stimulation and/or administration of monoaminergic agonists. We hypothesized that there are patterns of EMG signals from the forelimbs during quadrupedal locomotion that uniquely represent a signal for the “intent” to step with the hindlimbs. These observations led us to determine whether this type of “indirect” volitional control of stepping can be achieved after a complete spinal cord injury. The objective of this study was to develop an electronic bridge across the lesion of the spinal cord to facilitate hindlimb stepping after a complete mid-thoracic spinal cord injury in adult rats. Methods We developed an electronic spinal bridge that can detect specific patterns of EMG activity from the forelimb muscles to initiate electrical-enabling motor control (eEmc) of the lumbosacral spinal cord to enable quadrupedal stepping after a complete spinal cord transection in rats. A moving window detection algorithm was implemented in a small microprocessor to detect biceps brachii EMG activity bilaterally that then was used to initiate and terminate epidural stimulation in the lumbosacral spinal cord. We found dominant frequencies of 180–220 Hz in the EMG of the forelimb muscles during active periods, whereas these frequencies were between 0–10 Hz when the muscles were inactive. Results and conclusions Once the algorithm was validated to represent kinematically appropriate quadrupedal stepping, we observed that the algorithm could reliably detect, initiate, and facilitate stepping under different pharmacological conditions and at various treadmill speeds. PMID:22691460

  7. Effects of Rolipram on Adult Rat Oligodendrocytes and Functional Recovery after Contusive Cervical Spinal Cord Injury

    PubMed Central

    Beaumont, Eric; Whitaker, Christopher M.; Burke, Darlene A.; Hetman, Michal; Onifer, Stephen M.

    2009-01-01

    Traumatic human spinal cord injury causes devastating and long-term hardships. These are due to the irreparable primary mechanical injury and secondary injury cascade. In particular, oligodendrocyte cell death, white matter axon damage, spared axon demyelination, and the ensuing dysfunction in action potential conduction lead to the initial deficits and impair functional recovery. For these reasons, and that oligodendrocyte and axon survival may be related, various neuroprotective strategies after SCI are being investigated. We previously demonstrated that oligodendrocytes in the adult rat epicenter ventrolateral funiculus express 3′-5′-cyclic adenosine monophosphate-dependent phosphodiesterase 4 subtypes and that their death was attenuated up to 3 days after contusive cervical spinal cord injury when rolipram, a specific inhibitor of phosphodiesterase 4, was administered. Here, we report that 1) there are more oligodendrocyte somata in the adult rat epicenter ventrolateral funiculus, 2) descending and ascending axonal conductivity in the ventrolateral funiculus improves, and that 3) there are fewer hindlimb footfall errors during grid-walking at 5 weeks after contusive cervical spinal cord injury when rolipram is delivered for 2 weeks. This is the first demonstration of improved descending and ascending long-tract axonal conductivity across a spinal cord injury with this pharmacological approach. Since descending long-tract axonal conductivity did not return to normal, further evaluations of the pharmacokinetics and therapeutic window of rolipram as well as optimal combinations are necessary before consideration for neuroprotection in humans with spinal cord injury. PMID:19635528

  8. Blast overpressure induced axonal injury changes in rat brainstem and spinal cord

    PubMed Central

    Kallakuri, Srinivasu; Purkait, Heena S.; Dalavayi, Satya; VandeVord, Pamela; Cavanaugh, John M.

    2015-01-01

    Introduction: Blast induced neurotrauma has been the signature wound in returning soldiers from the ongoing wars in Iraq and Afghanistan. Of importance is understanding the pathomechansim(s) of blast overpressure (OP) induced axonal injury. Although several recent animal models of blast injury indicate the neuronal and axonal injury in various brain regions, animal studies related to axonal injury in the white matter (WM) tracts of cervical spinal cord are limited. Objective: The purpose of this study was to assess the extent of axonal injury in WM tracts of cervical spinal cord in male Sprague Dawley rats subjected to a single insult of blast OP. Materials and Methods: Sagittal brainstem sections and horizontal cervical spinal cord sections from blast and sham animals were stained by neurofilament light (NF-L) chain and beta amyloid precursor protein immunocytochemistry and observed for axonal injury changes. Results: Observations from this preliminary study demonstrate axonal injury changes in the form of prominent swellings, retraction bulbs, and putative signs of membrane disruptions in the brainstem and cervical spinal cord WM tracts of rats subjected to blast OP. Conclusions: Prominent axonal injury changes following the blast OP exposure in brainstem and cervical spinal WM tracts underscores the need for careful evaluation of blast induced injury changes and associated symptoms. NF-L immunocytochemistry can be considered as an additional tool to assess the blast OP induced axonal injury. PMID:26752889

  9. Efficient delivery of small interfering RNA into injured spinal cords in rats by photomechanical waves

    NASA Astrophysics Data System (ADS)

    Ando, Takahiro; Sato, Shunichi; Toyooka, Terushige; Kobayashi, Hiroaki; Nawashiro, Hiroshi; Ashida, Hiroshi; Obara, Minoru

    2011-03-01

    In the central nervous system, lack of axonal regeneration leads to permanent functional disabilities. In spinal cord injury (SCI), the over-expressions of intermediate filament (IF) proteins, such as glial fibrillary acidic protein (GFAP) and vimentin, are mainly involved in glial scar formation; these proteins work as both physical and biochemical barriers to axonal regeneration. Thus, silencing of these IF proteins would be an attractive strategy to treat SCI. In this study, we first attempted to deliver fluorescent probe-labeled siRNAs into injured spinal cords in rats by applying photomechanical waves (PMWs) to examine the capability of PMWs as a tool for siRNA delivery. Intense fluorescence from siRNAs was observed in much broader regions in the spinal cords with PMW application when compared with those with siRNA injection alone. Based on this result, we delivered siRNAs for GFAP and vimentin into injured spinal tissues in rats by applying PMWs. The treatment resulted in efficient silencing of the proteins at five days after SCI and a decrease of the cavity area in the injured tissue at three weeks after SCI when compared with those with siRNA injection alone. These results demonstrate the capability of PMWs for efficient delivery of siRNAs into injured spinal cords and treatment of SCIs.

  10. Transplantation of Glial Cells Enhances Action Potential Conduction of Amyelinated Spinal Cord Axons in the Myelin-Deficient Rat

    NASA Astrophysics Data System (ADS)

    Utzschneider, David A.; Archer, David R.; Kocsis, Jeffery D.; Waxman, Stephen G.; Duncan, Ian D.

    1994-01-01

    A central issue in transplantation research is to determine how and when transplantation of neural tissue can influence the development and function of the mammalian central nervous system. Of particular interest is whether electrophysiological function in the traumatized or diseased mammalian central nervous system can be improved by the replacement of cellular elements that are missing or damaged. Although it is known that transplantation of neural tissue can lead to functional improvement in models of neurological disease characterized by neuronal loss, less is known about results of transplantation in disorders of myelin. We report here that transplantation of glial cells into the dorsal columns of neonatal myelin-deficient rat spinal cords leads to myelination and a 3-fold increase in conduction velocity. We also show that impulses can propagate into and out of the transplant region and that axons myelinated by transplanted cells do not have impaired frequency-response properties. These results demonstrate that myelination following central nervous system glial cell transplantation enhances action potential conduction in myelin-deficient axons, with conduction velocity approaching normal values.

  11. Effects of riluzole on P2X7R expression in the spinal cord in rat model of neuropathic pain.

    PubMed

    Jiang, Kai; Zhuang, Ying; Yan, Ming; Chen, Hui; Ge, An-Qi; Sun, Li; Miao, Bei

    2016-04-01

    Neuropathic pain is becoming an intractable health threat, with its profound effect on quality of life, thus posing a major challenge to clinical therapy. Despite the reported efficacy of riluzole in some pain models, the underlying mechanism remains largely unknown. The present study aimed to assess the effects of riluzole in a rat model of neuropathic pain induced by chronic constriction injury (CCI). Subsequent to model establishment, paw withdrawal latencies (PWLs) and the paw withdrawal mecha threshold (PWT) rapidly decreased, coupled with inhibited microglial activation and upregulated P2X7R expression in the spinal cord dorsal horn (SCDH). Following intraperitoneal administration of riluzole (4mg/kg) once daily for 5 consecutive days as from day 3 after surgery, the mechanical allodynia and thermal hyperalgesia in the hind limbs were significantly attenuated. In addition, riluzole downregulated P2X7R expression and inhibited microglial activation in SCDH. Our results indicated that riluzole is effective in alleviating neuropathic pain and inhibiting microglial activation, presumably via the downregulated P2X7R expression in SCDH. PMID:26952972

  12. Antinociceptive Effects of Spinal Manipulative Therapy on Nociceptive Behavior of Adult Rats during the Formalin Test

    PubMed Central

    Onifer, Stephen M.; Reed, William R.; Sozio, Randall S.; Long, Cynthia R.

    2015-01-01

    Optimizing pain relief resulting from spinal manipulative therapies, including low velocity variable amplitude spinal manipulation (LVVA-SM), requires determining their mechanisms. Pain models that incorporate simulated spinal manipulative therapy treatments are needed for these studies. The antinociceptive effects of a single LVVA-SM treatment on rat nociceptive behavior during the commonly used formalin test were investigated. Dilute formalin was injected subcutaneously into a plantar hindpaw. Licking behavior was video-recorded for 5 minutes. Ten minutes of LVVA-SM at 20° flexion was administered with a custom-made device at the lumbar (L5) vertebra of isoflurane-anesthetized experimental rats (n = 12) beginning 10 minutes after formalin injection. Hindpaw licking was video-recorded for 60 minutes beginning 5 minutes after LVVA-SM. Control rats (n = 12) underwent the same methods except for LVVA-SM. The mean times spent licking the formalin-injected hindpaw of both groups 1–5 minutes after injection were not different. The mean licking time during the first 20 minutes post-LVVA-SM of experimental rats was significantly less than that of control rats (P < 0.001). The mean licking times of both groups during the second and third 20 minutes post-LVVA-SM were not different. Administration of LVVA-SM had a short-term, remote antinociceptive effect similar to clinical findings. Therefore, mechanistic investigations using this experimental approach are warranted. PMID:26693243

  13. Spinal cord thyrotropin releasing hormone receptors of morphine tolerant-dependent and abstinent rats

    SciTech Connect

    Rahmani, N.H.; Gulati, A.; Bhargava, H.N. )

    1990-07-01

    The effect of chronic administration of morphine and its withdrawal on the binding of 3H-(3-MeHis2)thyrotropin releasing hormone (3H-MeTRH) to membranes of the spinal cord of the rat was determined. Male Sprague-Dawley rats were implanted with either 6 placebo or 6 morphine pellets (each containing 75-mg morphine base) during a 7-day period. Two sets of animals were used. In one, the pellets were left intact at the time of sacrificing (tolerant-dependent) and in the other, the pellets were removed 16 hours prior to sacrificing (abstinent rats). In placebo-pellet-implanted rats, 3H-MeTRH bound to the spinal cord membranes at a single high affinity binding site with a Bmax of 21.3 +/- 1.6 fmol/mg protein, and an apparent dissociation constant Kd of 4.7 +/- 0.8 nM. In morphine tolerant-dependent or abstinent rats, the binding constants of 3H-MeTRH to spinal cord membranes were unaffected. Previous studies from this laboratory indicate that TRH can inhibit morphine tolerance-dependence and abstinence processes without modifying brain TRH receptors. Together with the present results, it appears that the inhibitory effect of TRH on morphine tolerance-dependence and abstinence is probably not mediated via central TRH receptors but may be due to its interaction with other neurotransmitter systems.

  14. Tidal volume and diaphragm muscle activity in rats with cervical spinal cord injury.

    PubMed

    Imagita, Hidetaka; Nishikawa, Akira; Sakata, Susumu; Nishii, Yasue; Minematsu, Akira; Moriyama, Hideki; Kanemura, Naohiko; Shindo, Hanae

    2015-03-01

    [Purpose] The purpose of this study was to make an experimental model of cervical spinal cord injury (CSCI) using Wistar rats, in order to analyze the influence of CSCI on the respiratory function. [Subjects] Thirty-two male 12-week-old Wistar rats were used. [Methods] The CSCI was made at the levels from C3 to C7, and we performed pneumotachography and electromyography (EMG) on the diaphragm. Computed tomography was used to determine the level of spinal cord damage. [Results] After the operation, the tidal volume of the rats with a C3 level injury decreased to approximately 22.3% of its pre-injury value. In addition, in the same rats, the diaphragmatic electromyogram activity decreased remarkably. Compared with before CSCI, the tidal volume decreased to 78.6% of its pre-injury value in CSCI at the C5 level, and it decreased to 94.1% of its pre-injury value in CSCI at the C7 level. [Conclusion] In the rats that sustained a CSCI in this study, the group of respiratory muscles that receive innervation from the thoracic spinal cord was paralyzed. Therefore, the EMG signal of the diaphragm increased. These results demonstrate that there is a relationship between respiratory function and the level of CSCI. PMID:25931732

  15. Transdermal monosialoganglioside with laser in the treatment of spinal cord lesion in rats

    PubMed Central

    de Souza, Fabiano Inácio; Cristante, Alexandre Fogaça; Marcon, Raphael Martus; Ferreira, Ricardo; dos Santos, Gustavo Bispo; de Barros, Tarcísio Eloy Pessoa

    2013-01-01

    OBJECTIVES: To evaluate the effects of monosialoganglioside (GM1) administered transdermally with laser in the recovery of spinal cord injury in rats. METHODS: Forty male Wistar rats underwent spinal cord contusion using the NYU Impactor. In Group 1, the rats received 0,2 ml of saline intraperitoneally daily; in Group 2, GM1 was administered intraperitoneally at a concentration of 30 mg/kg per day; in Group 3, rats were treated daily with laser at low temperature on the skin, and in Group 4, the daily laser session also contained GM1. All the groups were treated for 42 days. The animals were evaluated by the Basso, Baettie and Bresnahan (BBB) functional scale on days 7, 14, 21, 28, 35 and 42 after the injury, and by histopathology and motor evoked potential after 42 days of injury. RESULTS: The animals in Group 4 had higher BBB scores compared with the other groups. There were no differences between the groups, or in the comparisons over time. Histological evaluation showed no differences, and no differences were found in the motor evoked potential tests either. CONCLUSION: GM1 associated with the use of low-temperature laser shows no superior functional, neurological or histological results in the treatment of spinal cord lesions in rats. Evidence Level I, Experimental, Controlled, Animal Study. PMID:24453649

  16. Hyperbaric oxygen therapy reduces apoptosis after spinal cord injury in rats

    PubMed Central

    Long, Ying; Liang, Fang; Gao, Chunjin; Li, Zhuo; Yang, Jing

    2014-01-01

    Hyperbaric oxygen therapy (HBOT) protects brain tissue from inflammatory injury by suppressing mitochondrial apoptotic pathways. However, its neuroprotective mechanism via anti-apoptosis in spinal cord injury (SCI) is still unclear. In our study, Male Sprague-Dawley rats were randomly divided into three groups: sham-operated (SH), SCI model, and SCI + HBOT. Rats in each group were randomly divided into four sub-groups in a time-dependent manner (1 day, 3 days, 7 days and 14 days after surgery). Expression of adaptor molecule apoptosis-associated speck-like protein (ASC) and caspase-3 was evaluated at the indicated time after injury. Our data showed that HBOT downregulated expression of ASC in SCI rats at the mRNA and protein levels. HBOT mitigated caspase-3 release in injured spinal cord tissue. We conclude that HBOT prevents inflammation apoptosis after SCI, likely through suppression of ASC and caspase-3. PMID:25550916

  17. An experimental model for chronic compression of dorsal root ganglion produced by intervertebral foramen stenosis in the rat.

    PubMed

    Hu, S J; Xing, J L

    1998-07-01

    Under anesthesia and sterile surgery, a small stainless steel rod (4 mm in length and 0.5-0.8 mm in diameter) was inserted into the L5 intervertebral foramen in the rat, developing intervertebral foramen stenosis and hence producing a chronic steady compression of the dorsal root ganglion (DRG). The hind paw on the injured side exhibited a significant reduction in the latency of foot withdrawal to noxious heat and manifested a persistent heat hyperalgesia 5-35 days after surgery. Injection of 1% carrageenan into the intervertebral foramen, presumably causing inflammation of the DRG, also produced hyperalgesia to heat on the hind paw of the injured side 5-21 days after surgery. Extracellular electrophysiological recordings from myelinated dorsal root fibers were performed in vivo. Spontaneous activity was present in 21.5% of the fibers recorded from DRG neurons injured with chronic compression in contrast to 1.98% from uninjured DRG neurons. The pattern of spontaneous activity was periodic and bursting in 75.3% of the spontaneously active fibers. These neurons had a greatly enhanced sensitivity to mechanical stimulation of the injured DRG and a prolonged after discharge. In response to TEA, topically applied to the DRG, excitatory responses were evoked in the injured, but not the uninjured, DRG neurons. Application of this experimental model may further our understanding of the neural mechanisms by which chronic compression of DRG induces low back pain and sciatica. PMID:9755014

  18. Intervention of electroacupuncture on spinal p38 MAPK/ATF-2/VR-1 pathway in treating inflammatory pain induced by CFA in rats

    PubMed Central

    2013-01-01

    Background Previous studies have demonstrated that p38 MAPK signal transduction pathway plays an important role in the development and maintenance of inflammatory pain. Electroacupuncture (EA) can suppress the inflammatory pain. However, the relationship between EA effect and p38 MAPK signal transduction pathway in inflammatory pain remains poorly understood. It is our hypothesis that p38 MAPK/ATF-2/VR-1 and/or p38 MAPK/ATF-2/COX-2 signal transduction pathway should be activated by inflammatory pain in CFA-injected model. Meanwhile, EA may inhibit the activation of p38 MAPK signal transduction pathway. The present study aims to investigate that anti-inflammatory and analgesic effect of EA and its intervention on the p38 MAPK signal transduction pathway in a rat model of inflammatory pain. Results EA had a pronounced anti-inflammatory and analgesic effect on CFA-induced chronic inflammatory pain in rats. EA could quickly raise CFA-rat’s paw withdrawal thresholds (PWTs) and maintain good and long analgesic effect, while it subdued the ankle swelling of CFA rats only at postinjection day 14. EA could down-regulate the protein expressions of p-p38 MAPK and p-ATF-2, reduced the numbers of p-p38 MAPK-IR cells and p-ATF-2-IR cells in spinal dorsal horn in CFA rats, inhibited the expressions of both protein and mRNA of VR-1, but had no effect on the COX-2 mRNA expression. Conclusions The present study indicates that inhibiting the activation of spinal p38 MAPK/ATF-2/VR-1 pathway may be one of the main mechanisms via central signal transduction pathway in the process of anti-inflammatory pain by EA in CFA rats. PMID:23517865

  19. Intrathecal amantadine for prolonged spinal blockade of sensory and motor functions in rats.

    PubMed

    Tzeng, Jann-Inn; Kan, Chung-Dann; Wang, Jieh-Neng; Wang, Jhi-Joung; Lin, Heng-Teng; Hung, Ching-Hsia

    2016-08-01

    We aimed to compare the hypothesized local anesthetic action of amantadine (1-adamantanamine) with that of the known local anesthetic mepivacaine. Motor, proprioceptive, and nociceptive functions were evaluated in rats after intrathecal administration. Amantadine elicited spinal anesthesia in a dose-related fashion and produced a better sensory-selective action over motor blockade (P < 0.01). On the 50% effective dose (ED50 ) basis, the rank of potency on spinal motor, proprioceptive, and nociceptive block was mepivacaine > amantadine (P < 0.01 for the differences). Amantadine (63.5 μmol/kg) and mepivacaine (7.1 μmol/kg) produced complete spinal block of motor function, proprioception, and nociception. On an equipotent basis (ED25 , ED50 , and ED75 ), the duration of amantadine was longer (P < 0.01) than that of mepivacaine on spinal motor, proprioceptive, and nociceptive block. Our preclinical data demonstrated that amantadine was less potent than mepivacaine at producing spinal anesthesia. The spinal block duration produced by amantadine was greater than that produced by mepivacaine. Both amantadine and mepivacaine produced a markedly nociceptive-specific blockade. PMID:27011292

  20. Biocompatibility of reduced graphene oxide nanoscaffolds following acute spinal cord injury in rats

    PubMed Central

    Palejwala, Ali H.; Fridley, Jared S.; Mata, Javier A.; Samuel, Errol L. G.; Luerssen, Thomas G.; Perlaky, Laszlo; Kent, Thomas A.; Tour, James M.; Jea, Andrew

    2016-01-01

    Background: Graphene has unique electrical, physical, and chemical properties that may have great potential as a bioscaffold for neuronal regeneration after spinal cord injury. These nanoscaffolds have previously been shown to be biocompatible in vitro; in the present study, we wished to evaluate its biocompatibility in an in vivo spinal cord injury model. Methods: Graphene nanoscaffolds were prepared by the mild chemical reduction of graphene oxide. Twenty Wistar rats (19 male and 1 female) underwent hemispinal cord transection at approximately the T2 level. To bridge the lesion, graphene nanoscaffolds with a hydrogel were implanted immediately after spinal cord transection. Control animals were treated with hydrogel matrix alone. Histologic evaluation was performed 3 months after the spinal cord transection to assess in vivo biocompatibility of graphene and to measure the ingrowth of tissue elements adjacent to the graphene nanoscaffold. Results: The graphene nanoscaffolds adhered well to the spinal cord tissue. There was no area of pseudocyst around the scaffolds suggestive of cytotoxicity. Instead, histological evaluation showed an ingrowth of connective tissue elements, blood vessels, neurofilaments, and Schwann cells around the graphene nanoscaffolds. Conclusions: Graphene is a nanomaterial that is biocompatible with neurons and may have significant biomedical application. It may provide a scaffold for the ingrowth of regenerating axons after spinal cord injury. PMID:27625885

  1. Glucose Injections into the Dorsal Hippocampus or Dorsolateral Striatum of Rats Prior to T-Maze Training: Modulation of Learning Rates and Strategy Selection

    ERIC Educational Resources Information Center

    Canal, Clinton E.; Stutz, Sonja J.; Gold, Paul E.

    2005-01-01

    The present experiments examined the effects of injecting glucose into the dorsal hippocampus or dorsolateral striatum on learning rates and on strategy selection in rats trained on a T-maze that can be solved by using either a hippocampus-sensitive place or striatum-sensitive response strategy. Percentage strategy selection on a probe trial…

  2. Inhibition of acid-sensing ion channels by levo-tetrahydropalmatine in rat dorsal root ganglion neurons.

    PubMed

    Liu, Ting-Ting; Qu, Zu-Wei; Qiu, Chun-Yu; Qiu, Fang; Ren, Cuixia; Gan, Xiong; Peng, Fang; Hu, Wang-Ping

    2015-02-01

    Levo-tetrahydropalmatine (l-THP), a main bioactive Chinese herbal constituent from the genera Stephania and Corydalis, has been in use in clinical practice for years in China as a traditional analgesic agent. However, the mechanism underlying the analgesic action of l-THP is poorly understood. This study shows that l-THP can exert an inhibitory effect on the functional activity of native acid-sensing ion channels (ASICs), which are believed to mediate pain caused by extracellular acidification. l-THP dose dependently decreased the amplitude of proton-gated currents mediated by ASICs in rat dorsal root ganglion (DRG) neurons. l-THP shifted the proton concentration-response curve downward, with a decrease of 40.93% ± 8.45% in the maximum current response to protons, with no significant change in the pH0.5 value. Moreover, l-THP can alter the membrane excitability of rat DRG neurons to acid stimuli. It significantly decreased the number of action potentials and the amplitude of the depolarization induced by an extracellular pH drop. Finally, peripherally administered l-THP inhibited the nociceptive response to intraplantar injection of acetic acid in rats. These results indicate that l-THP can inhibit the functional activity of ASICs in dissociated primary sensory neurons and relieve acidosis-evoked pain in vivo, which for the first time provides a novel peripheral mechanism underlying the analgesic action of l-THP. PMID:25395088

  3. Nesfatin-1 increases intracellular calcium concentration by protein kinase C activation in cultured rat dorsal root ganglion neurons.

    PubMed

    Ozcan, Mete; Gok, Zeynep Betul; Kacar, Emine; Serhatlioglu, Ihsan; Kelestimur, Haluk

    2016-04-21

    Nesfatin-1 is a recently identified anorexigenic hypothalamic polypeptide derived from the posttranslational processing of nucleobindin 2 (NUCB2). Several studies have indicated that this neuropeptide may be participated in somatosensory and visceral transmission including pain signals in addition to energy metabolism. The aim of this study was to explore the possible role of nesfatin-1 in the transmission of peripheral neural signals by investigating the effects of nesfatin-1 on intracellular free calcium levels ([Ca(2+)]i) in cultured neonatal rat dorsal root ganglion (DRG) neurons. The effects of nesfatin-1 on [Ca(2+)]i in DRG neurons were investigated by using an in vitro calcium imaging system. DRG neurons were grown in primary culture following enzymatic and mechanical dissociation of ganglia from 1-or 2-day-old neonatal Wistar rats. Using the fura-2-based calcium imaging technique, the effects of nesfatin-1 on [Ca(2+)]i and role of the protein kinase C (PKC)-mediated pathway in nesfatin-1 effect were assessed. Nesfatin-1 elevated [Ca(2+)]i in cultured DRG neurons. The response was prevented by pretreating the cells with pertussis toxin. The protein kinase C inhibitor chelerythrine chloride suppressed nesfatin-1-induced rise in [Ca(2+)]i. The result shows that nesfatin-1 interacts with a G protein-coupled receptor, leading to an increase of [Ca(2+)]i, which is linked to protein kinase C activation in cultured rat DRG neurons. PMID:26975784

  4. Behavioral and Histopathological Study of Changes in Spinal Cord Injured Rats Supplemented with Spirulina platensis

    PubMed Central

    Che Ramli, Muhammad Danial

    2014-01-01

    Spinal cord injury (SCI) is a devastating disease that leads to permanent disability and causes great suffering. The resulting neurological dysfunction and paralysis is proportional to the severity of the trauma itself. Spirulina is widely used as a nutritional supplement due to its high protein and antioxidant content. In the present study, the protective effect of the Spirulina treatment on locomotor function and morphological damage after SCI was investigated. Seventy Sprague-Dawley (SD) rats were divided into three groups: Sham (laminectomy alone), Control (laminectomy with SCI), and Experimental (laminectomy with SCI +180 mg/kg per day Spirulina platensis). A laminectomy was performed at T12 and an Inox No.2 modified forceps was used to perform a partial crush injury on the spinal cord. The rats were then perfused at 3, 7, 14, 21, and 28 days after injury for morphological investigations. The injured rat spinal cord indicated a presence of hemorrhage, cavity, and necrosis. Pretreatment with Spirulina significantly improved the locomotor function and showed a significant reduction on the histological changes. The experimental results observed in this study suggest that treatment with Spirulina platensis possesses potential benefits in improving hind limb locomotor function and reducing morphological damage to the spinal cord. PMID:25152764

  5. Effects of hemorrhagic hypotension on tyrosine concentrations in rat spinal cord and plasma

    NASA Technical Reports Server (NTRS)

    Conlay, L. A.; Maher, T. J.; Roberts, C. H.; Wurtman, R. J.

    1988-01-01

    Tyrosine is the precursor for catecholamine neurotransmitters. When catecholamine-containing neurons are physiologically active (as sympathoadrenal cells are in hypotension), tyrosine administration increases catecholamine synthesis and release. Since hypotension can alter plasma amino acid composition, the effects of an acute hypotensive insult on tyrosine concentrations in plasma and spinal cord were examined. Rats were cannulated and bled until the systolic blood pressure was 50 mmHg, or were kept normotensive for 1 h. Tyrosine and other large neutral amino acids (LNAA) known to compete with tyrosine for brain uptake were assayed in plasma and spinal cord. The rate at which intra-arterial (H-3)tyrosine disappeared from the plasma was also estimated in hemorrhaged and control rats. In plasma of hemorrhaged animals, both the tyrosine concentration and the tyrosine/LNAA ratio was elevated; moreover, the disappearance of (H-3)tyrosine was slowed. Tyrosine concentrations also increased in spinal cords of hemorrhaged-hypotensive rats when compared to normotensive controls. Changes in plasma amino acid patterns may thus influence spinal cord concentrations of amino acid precursors for neurotransmitters during the stress of hemorrhagic shock.

  6. Antiallodynic effects of alpha lipoic acid in an optimized RR-EAE mouse model of MS-neuropathic pain are accompanied by attenuation of upregulated BDNF-TrkB-ERK signaling in the dorsal horn of the spinal cord.

    PubMed

    Khan, Nemat; Gordon, Richard; Woodruff, Trent M; Smith, Maree T

    2015-06-01

    Neuropathic pain may affect patients with multiple sclerosis (MS) even in early disease. In an experimental autoimmune encephalomyelitis (EAE)-mouse model of MS, chronic alpha lipoic acid (ALA) treatment reduced clinical disease severity, but MS-neuropathic pain was not assessed. Hence, we investigated the pain-relieving efficacy and mode of action of ALA using our optimized relapsing-remitting (RR)-EAE mouse model of MS-associated neuropathic pain. C57BL/6 mice were immunized with MOG35-55 and adjuvants (Quil A and pertussis toxin) to induce RR-EAE; sham-mice received adjuvants only. RR-EAE mice received subcutaneous ALA (3 or 10 mg kg(-1) day(-1)) or vehicle for 21 days (15-35 d.p.i.; [days postimmunization]); sham-mice received vehicle. Hindpaw hypersensitivity was assessed blinded using von Frey filaments. Following euthanasia (day 35 d.p.i.), lumbar spinal cords were removed for immunohistochemical and molecular biological assessments. Fully developed mechanical allodynia in the bilateral hindpaws of vehicle-treated RR-EAE mice was accompanied by marked CD3(+) T-cell infiltration, microglia activation, and increased brain-derived neurotrophic factor (BDNF)-tyrosine kinase B (TrkB) signaling in the dorsal horn of the lumbar spinal cord. Consequently, phospho-ERK, a marker of central sensitization in neuropathic pain, was upregulated in the spinal dorsal horn. Importantly, hindpaw hypersensitivity was completely attenuated in RR-EAE mice administered ALA at 10 mg kg(-1) day(-1) but not 3 mg kg(-1) day(-1). The antiallodynic effect of ALA (10 mg kg(-1) day(-1)) was associated with a marked reduction in the aforementioned spinal dorsal horn markers to match their respective levels in the vehicle-treated sham-mice. Our findings suggest that ALA at 10 mg kg(-1) day(-1) produced its antiallodynic effects in RR-EAE mice by reducing augmented CD3(+) T-cell infiltration and BDNF-TrkB-ERK signaling in the spinal dorsal horn. PMID:26171221

  7. Intrathecal Amylin and Salmon Calcitonin Affect Formalin Induced c-Fos Expression in the Spinal Cord of Rats

    PubMed Central

    Khoshdel, Zahra; Takhshid, Mohammad Ali; Owji, Ali Akbar

    2014-01-01

    Background: Amylin and Salmon Calcitonin belong to the calcitonin family of peptides and have high affinity binding sites in the rat spinal cord. The aim of this study was to characterize receptors for Amylin and Salmon Calcitonin functionally in the spinal cord of rats. We assessed the expression of c-Fos in response to intraplantar formalin in the lumbar regions of the spinal cord in conscious rats. Methods: Amylin (0.05 nmoles) or Salmon Calcitonin (0.005 nmoles) was administered intrathecally (i.t.) 10 minutes before the start of the formalin test. Antagonists were injected intrathecally 10 minutes before the administration of either of the peptides. Results: Two hours after formalin stimulation, rats pretreated intrathecally by either Amylin or Salmon Calcitonin, showed lower numbers of c-Fos immunoreactive nuclei in their lumbar spinal cord as compared to rats pretreated with saline. These effects were reversed upon co-administration of either of the Amylin antagonists AC187 or rat amylin8-37, but not rat α-CGRP8-37. A few cells with c-Fos immunoreactivity were found in the lumbar spinal cord of rats two hours after i.t. injection of saline, Amylin and/or Salmon Calcitonin. However, Fos-like immunoreactivity was increased in the lumbar spinal cord two hours after i.t. treatment of either of the antagonists AC187 and rat amylin8-37,when compared to saline treated rats. Conclusion: Both Amylin and Salmon Calcitonin inhibit formalin induced c-Fos expression in the rat lumbar spinal cord when administered intrathecally. Effects of the two peptides were possibly produced by undefined receptors. PMID:25429177

  8. Shp-1 dephosphorylates TRPV1 in dorsal root ganglion neurons and alleviates CFA-induced inflammatory pain in rats.

    PubMed

    Xiao, Xing; Zhao, Xiao-Tao; Xu, Ling-Chi; Yue, Lu-Peng; Liu, Feng-Yu; Cai, Jie; Liao, Fei-Fei; Kong, Jin-Ge; Xing, Guo-Gang; Yi, Ming; Wan, You

    2015-04-01

    Transient receptor potential vanilloid 1 (TRPV1) receptors are expressed in nociceptive neurons of rat dorsal root ganglions (DRGs) and mediate inflammatory pain. Nonspecific inhibition of protein-tyrosine phosphatases (PTPs) increases the tyrosine phosphorylation of TRPV1 and sensitizes TRPV1. However, less is known about tyrosine phosphorylation's implication in inflammatory pain, compared with that of serine/threonine phosphorylation. Src homology 2 domain-containing tyrosine phosphatase 1 (Shp-1) is a key phosphatase dephosphorylating TRPV1. In this study, we reported that Shp-1 colocalized with and bound to TRPV1 in nociceptive DRG neurons. Shp-1 inhibitors, including sodium stibogluconate and PTP inhibitor III, sensitized TRPV1 in cultured DRG neurons. In naive rats, intrathecal injection of Shp-1 inhibitors increased both TRPV1 and tyrosine-phosphorylated TRPV1 in DRGs and induced thermal hyperalgesia, which was abolished by pretreatment with TRPV1 antagonists capsazepine, BCTC, or AMG9810. Complete Freund's adjuvant (CFA)-induced inflammatory pain in rats significantly