Science.gov

Sample records for rat spinal dorsal

  1. Dorsal column sensory axons degenerate due to impaired microvascular perfusion after spinal cord injury in rats.

    PubMed

    Muradov, Johongir M; Ewan, Eric E; Hagg, Theo

    2013-11-01

    The mechanisms contributing to axon loss after spinal cord injury (SCI) are largely unknown but may involve microvascular loss as we have previously suggested. Here, we used a mild contusive injury (120 kdyn IH impactor) at T9 in rats focusing on ascending primary sensory dorsal column axons, anterogradely traced from the sciatic nerves. The injury caused a rapid and progressive loss of dorsal column microvasculature and oligodendrocytes at the injury site and penumbra and an ~70% loss of the sensory axons by 24 h. To model the microvascular loss, focal ischemia of the T9 dorsal columns was achieved via phototoxic activation of intravenously injected rose bengal. This caused an ~53% loss of sensory axons and an ~80% loss of dorsal column oligodendrocytes by 24 h. Axon loss correlated with the extent and axial length of microvessel and oligodendrocyte loss along the dorsal column. To determine if oligodendrocyte loss contributes to axon loss, the glial toxin ethidium bromide (EB; 0.3 μg/μl) was microinjected into the T9 dorsal columns, and resulted in an ~88% loss of dorsal column oligodendrocytes and an ~56% loss of sensory axons after 72 h. EB also caused an ~75% loss of microvessels. Lower concentrations of EB resulted in less axon, oligodendrocyte and microvessel loss, which were highly correlated (R(2) = 0.81). These data suggest that focal spinal cord ischemia causes both oligodendrocyte and axon degeneration, which are perhaps linked. Importantly, they highlight the need of limiting the penumbral spread of ischemia and oligodendrocyte loss after SCI in order to protect axons.

  2. Effects of spinally administered adenine on dorsal horn neuronal responses in a rat model of inflammation.

    PubMed

    Matthews, Elizabeth A; Dickenson, Anthony H

    2004-02-19

    A novel G-protein-coupled receptor with adenine identified as the endogenous ligand has recently been described. In vivo electrophysiological techniques in the rat were used to record the response of dorsal horn neurones in response to transcutaneous electrical stimulation to the hindpaw receptive field. Spinal adenine (1-1000 microg) exerted facilitatory effects on the electrically-evoked neuronal responses, in a mildly dose-related manner. After establishment of carrageenan-induced inflammation to the hindpaw this excitatory effect of adenine was still apparent, yet reduced. C-fibre-evoked responses and other nociceptive related measures were most susceptible to the effects of adenine, whereas non-nociceptive Abeta-fibre evoked activity remained unaffected. Thus, activation of the adenine receptor site, via spinally applied adenine, suggests a pronociceptive role in nociceptive sensory transmission.

  3. 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

  4. Endomorphins suppress nociception-induced c-Fos and Zif/268 expression in the rat spinal dorsal horn.

    PubMed

    Tateyama, Shingo; Ikeda, Tetsuya; Kosai, Kazuko; Nakamura, Tadashi; Kasaba, Toshiharu; Takasaki, Mayumi; Nishimori, Toshikazu

    2002-09-06

    We evaluated the potency of endomorphin-1 and -2 as endogenous ligands on c-Fos and Zif/268 expression in the spinal dorsal horn by formalin injection to the rat hind paw. Endomorphin-1, -2, or morphine was administered intrathecally or intracerebroventricularly 5 min before formalin injection (5%, 100 microl). All drugs produced marked reductions of formalin-induced c-Fos and Zif/268 immunoreactivity in laminae I and II, and laminae V and VI in the rat lumbar spinal cord. The reductions of Zif/268 expression by endomorphins were greater than those by morphine, while the reductions of c-Fos expression by endomorphins were smaller than those by morphine. These effects of endomorphins were attenuated by pretreatment with naloxone. These results indicate that endomorphin-1 and -2 act as endogenous ligands of mu-opioid receptor in neurons of the spinal dorsal horn and suppress the processing of nociceptive information in the central nervous system.

  5. 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

  6. Stereological study on the number of synapses in the rat spinal dorsal horn with painful diabetic neuropathy induced by streptozotocin.

    PubMed

    Lin, Jing-Yan; Huang, Xiao-Li; Chen, Jing; Yang, Zheng-Wei; Lin, Jing; Huang, San; Peng, Bin

    2017-03-02

    Our previous studies showed that direct injury to the sciatic nerve (chronic constriction injury or axotomy) is associated with a numerical increase in synaptic number in the rat spinal dorsal horn. The aim of this study was to determine whether painful diabetic neuropathy (PDN) was also associated with numerical changes in the synaptic or neuronal numbers in the spinal dorsal horn. Overall, 17 adult SD rats were allocated randomly into the control group (n=5) and the streptozotocin (STZ) group (n=12). STZ was injected intraperitoneally to induce diabetes. In the STZ group, seven rats (STZ-H) showed hyperglycemia (fasting blood glucose >11.1 mM) and the rest of the five rats (STZ-N) did not. Rats were fed and observed for 28 days after hyperglycemia. Two of the seven STZ-H rats died of infection during the observation period. Body weight and paw withdraw threshold (PWT) decreased in the rest of the five STZ-H rats. Twenty-eight days after hyperglycemia, the L5 segment of the spinal cord was removed; paraffin-embedded sections were prepared and stained with Nissl's method and synaptophysin immunohistochemistry, respectively. The optical dissector (a stereological technique) was used to estimate the numbers of neurons and synapses in the spinal dorsal horn. Compared with the control group, the synaptic number and ratio between the numbers of synapses and neurons in the L5 segment of the spinal dorsal horn were increased significantly in the STZ-H rats (P<0.05), whereas the neuronal number did not change significantly (P>0.05). Parameters of STZ-N rats showed no significant changes. In conclusion, PDN, a form of neuropathic pain, is also associated with a synaptic plasticity (numerical increase) in the spinal dorsal horn. This numerical change might be the reason for central sensitization resulting in reduced pain threshold, enhanced responsiveness, and expanded receptive fields associated with PDN. Therefore, our studies indicate that neuropathic pain conditions

  7. Neonatal local noxious insult affects gene expression in the spinal dorsal horn of adult rats.

    PubMed

    Ren, Ke; Novikova, Svetlana I; He, Fang; Dubner, Ronald; Lidow, Michael S

    2005-09-22

    Neonatal noxious insult produces a long-term effect on pain processing in adults. Rats subjected to carrageenan (CAR) injection in one hindpaw within the sensitive period develop bilateral hypoalgesia as adults. In the same rats, inflammation of the hindpaw, which was the site of the neonatal injury, induces a localized enhanced hyperalgesia limited to this paw. To gain an insight into the long-term molecular changes involved in the above-described long-term nociceptive effects of neonatal noxious insult at the spinal level, we performed DNA microarray analysis (using microarrays containing oligo-probes for 205 genes encoding receptors and transporters for glutamate, GABA, and amine neurotransmitters, precursors and receptors for neuropeptides, and neurotrophins, cytokines and their receptors) to compare gene expression profiles in the lumbar spinal dorsal horn (LDH) of adult (P60) male rats that received neonatal CAR treatment within (at postnatal day 3; P3) and outside (at postnatal 12; P12) of the sensitive period. The data were obtained both without inflammation (at baseline) and during complete Freund's adjuvant induced inflammation of the neonatally injured paw. The observed changes were verified by real-time RT-PCR. This study revealed significant basal and inflammation-associated aberrations in the expression of multiple genes in the LDH of adult animals receiving CAR injection at P3 as compared to their expression levels in the LDH of animals receiving either no injections or CAR injection at P12. In particular, at baseline, twelve genes (representing GABA, serotonin, adenosine, neuropeptide Y, cholecystokinin, opioid, tachykinin and interleukin systems) were up-regulated in the bilateral LDH of the former animals. The baseline condition in these animals was also characterized by up-regulation of seven genes (encoding members of GABA, cholecystokinin, histamine, serotonin, and neurotensin systems) in the LDH ipsilateral to the neonatally-injured paw. The

  8. 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

  9. Anterior pretectal stimulation alters the responses of spinal dorsal horn neurones to cutaneous stimulation in the rat.

    PubMed Central

    Rees, H; Roberts, M H

    1987-01-01

    1. The behavioural effects of stimulating sites in the anterior pretectal nucleus (a.p.t.n.) were studied in unanaesthetized rats; 1-2 weeks later these rats were anaesthetized with Fluothane and the effects of similar electrical stimulation determined on the responses of spinal neurones to cutaneous stimuli. 2. Stimulation of the a.p.t.n. for 15 s with 35 microA r.m.s. sine-wave current inhibited the tail-flick response to noxious heat of unanaesthetized animals for up to 1 h. 3. Stimulation of the same sites in anaesthetized rats inhibited the responses to noxious heat of forty-two multireceptive and two high-threshold neurones located deep in the spinal dorsal horn. 4. The high-threshold responses of seven cells were unaffected or slightly potentiated by pretectal stimulation. These seven cells were all recorded from the dorsal margin of the dorsal horn, were not multireceptive neurones and could be made to discharge only by water above 50 degrees C. 5. The responses of twelve multireceptive cells to low-threshold stimulation were not affected by pretectal stimulation. All these cells were recorded from deep within the dorsal horn. 6. On ten occasions, cells deep in the dorsal horn were identified as projection neurones which were driven antidromically by high-frequency (300 Hz) stimulation of the contralateral anterolateral tract at cervical levels. The high-threshold responses of all these cells were reduced by pretectal stimulation. No cells were driven antidromically by pretectal stimulation. 7. Ipsilateral lesions of the dorsolateral funiculus abolished the inhibitory effects of prectectal stimulation. Lesions of the dorsal columns were without effect. 8. It is concluded that stimulation of the a.p.t.n. inhibits the tail-flick reflex of unanaesthetized rats and inhibits the high-threshold discharge of deep dorsal horn cells to cutaneous stimuli in anaesthetized rats. Cells recorded from the dorsal margin of the dorsal horn are not affected. The inhibition

  10. [Effect of spontaneous firing of injured dorsal root ganglion neuron on excitability of wide dynamic range neuron in rat spinal dorsal horn].

    PubMed

    Song, Ying; Zhang, Yong-Mei; Xu, Jie; Wu, Jing-Ru; Qin, Xia; Hua, Rong

    2013-10-25

    The aim of the paper is to study the effect of spontaneous firing of injured dorsal root ganglion (DRG) neuron in chronic compression of DRG (CCD) model on excitability of wide dynamic range (WDR) neuron in rat spinal dorsal horn. In vivo intracellular recording was done in DRG neurons and in vivo extracellular recording was done in spinal WDR neurons. After CCD, incidence of spontaneous discharge and firing frequency enhanced to 59.46% and (4.30 ± 0.69) Hz respectively from 22.81% and (0.60 ± 0.08) Hz in normal control group (P < 0.05). Local administration of 50 nmol/L tetrodotoxin (TTX) on DRG neuron in CCD rats decreased the spontaneous activities of WDR neurons from (191.97 ± 45.20)/min to (92.50 ± 30.32)/min (P < 0.05). On the other side, local administration of 100 mmol/L KCl on DRG neuron evoked spontaneous firing in a reversible way (n = 5) in silent WDR neurons of normal rats. There was 36.36% (12/33) WDR neuron showing after-discharge in response to innocuous mechanical stimuli on cutaneous receptive field in CCD rats, while after-discharge was not seen in control rats. Local administration of TTX on DRG with a concentration of 50 nmol/L attenuated innocuous electric stimuli-evoked after-discharge of WDR neurons in CCD rats in a reversible manner, and the frequency was decreased from (263 ± 56.5) Hz to (117 ± 30) Hz (P < 0.05). The study suggests that the excitability of WDR neurons is influenced by spontaneous firings of DRG neurons after CCD.

  11. Gabapentin inhibits γ-Amino butyric acid release in the locus coeruleus but not in the spinal dorsal horn after peripheral nerve injury in rats

    PubMed Central

    Yoshizumi, Masaru; Parker, Renee A.; Eisenach, James C.; Hayashida, Ken-ichiro

    2012-01-01

    Background Gabapentin reduces acute postoperative and chronic neuropathic pain, but its sites and mechanisms of action are unclear. Based on previous electrophysiologic studies, we tested whether gabapentin reduced γ-Amino butyric acid (GABA) release in the locus coeruleus (LC), a major site of descending inhibition, rather than in the spinal cord. Methods Male Sprague-Dawley rats with or without L5-L6 spinal nerve ligation (SNL) were used. Immunostaining for glutamic acid decarboxylase and GABA release in synaptosomes and microdialysates were examined in the LC and spinal dorsal horn. Results Basal GABA release and expression of glutamic acid decarboxylase increased in the LC but decreased in the spinal dorsal horn following SNL. In microdialysates from the LC, intravenously administered gabapentin decreased extracellular GABA concentration in normal and SNL rats. In synaptosomes prepared from the LC, gabapentin and other α2δ ligands inhibited KCl-evoked GABA release in normal and SNL rats. In microdialysates from the spinal dorsal horn, intravenous gabapentin did not alter GABA concentrations in normal rats but slightly increased them in SNL rats. In synaptosomes from the spinal dorsal horn, neither gabapentin nor other α2δ ligands affected KCl-evoked GABA release in normal and SNL rats. Discussion These results suggest that peripheral nerve injury induces plasticity of GABAergic neurons differently in the LC and spinal dorsal horn, and that gabapentin reduces pre-synaptic GABA release in the LC but spinal dorsal horn. The present study supports the idea that gabapentin activates descending noradrenergic inhibition via disinhibition of LC neurons. PMID:22487864

  12. Cholera toxin B subunit labeling in lamina II of spinal cord dorsal horn following chronic inflammation in rats.

    PubMed

    Ma, Qing Ping; Tian, Li

    2002-07-26

    We have investigated the effect of inflammation on the labeling pattern of cholera toxin B subunit (CTB)-conjugated horseradish peroxidase, an A-fiber marker, by an intra-sciatic nerve injection of the tracer. Following chronic inflammation in one hind paw in rats, there was substantial CTB labeling in lamina II of the spinal dorsal horn, which is normally absent. However, there was no change in the labeling pattern of wheat germ agglutinin or fluoride resistant acid phosphatase/thiamine monophosphatase, two C-fiber markers. The CTB labeling in lamina II after peripheral nerve injury has been interpreted as central sprouting of A-fibers or uptake of the tracer by injured C-fibers. Our results suggest that chronic inflammation and nerve injury may share some common mechanisms in generating allodynia and hyperalgesia.

  13. A survey of spinal dorsal horn neurones encoding the spatial organization of withdrawal reflexes in the rat.

    PubMed

    Schouenborg, J; Weng, H R; Kalliomäki, J; Holmberg, H

    1995-01-01

    The withdrawal reflex pathways to hindlimb muscles have an elaborate spatial organization in the rat. In short, the distribution of sensitivity within the cutaneous receptive field of a single muscle has a spatial pattern that is a mirror image of the spatial pattern of the withdrawal of the skin surface ensuing on contraction in the respective muscle. In the present study, a search for neurones encoding the specific spatial input-output relationship of withdrawal reflexes to single muscles was made in the lumbosacral spinal cord in halothane/nitrous oxide-anaesthetized rats. The cutaneous receptive fields of 147 dorsal horn neurones in the L4-5 segments receiving a nociceptive input and a convergent input from A and C fibres from the hindpaw were studied. The spatial pattern of the response amplitude within the receptive fields of 118 neurones was quantitatively compared with those of withdrawal reflexes to single muscles. Response patterns exhibiting a high similarity to those of withdrawal reflexes to single muscles were found in 27 neurones located in the deep dorsal horn. Twenty-six of these belonged to class 2 (responding to tactile and nociceptive input) and one belonged to class 3 (responding only to nociceptive input). None of the neurones tested (n = 20) with reflex-like response patterns could be antidromically driven from the upper cervical cord, suggesting that they were spinal interneurones. With some overlap, putative interneurones of the withdrawal reflexes to the plantar flexors of the digits, the plantar flexors of the ankle, the pronators, the dorsiflexors of the ankle, and a flexor of the knee, were found in succession in a mediolateral direction.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Differentiation and migration of astrocytes in the spinal cord following dorsal root injury in the adult rat.

    PubMed

    Kozlova, Elena N

    2003-02-01

    Nerve fibre degeneration in the spinal cord is accompanied by astroglial proliferation. It is not known whether these cells proliferate in situ or are recruited from specific regions harbouring astroglial precursors. We found cells expressing nestin, characteristic of astroglial precursors, at the dorsal surface of the spinal cord on the operated side from 30 h after dorsal root injury. Nestin-expressing cells dispersed to deeper areas of the dorsal funiculus and dorsal horn on the operated side during the first few days after injury. Injection of bromodeoxyuridine (BrdU) 2 h before the end of the experiment, at 30 h after injury, revealed numerous BrdU-labelled, nestin-positive cells in the dorsal superficial region. In animals surviving 20 h after BrdU injection at 28 h postlesion, cells double-labelled with BrdU and nestin were also found in deeper areas. Labeling with BrdU 2 h before perfusion showed proliferation of microglia and radial astrocytes in the ventral and lateral funiculi on both sides of the spinal cord 30 h after injury. Nestin-positive cells coexpressed the calcium-binding protein Mts1, a marker for white matter astrocytes, in the dorsal funiculus, and were positive for glial fibrillary acidic protein (GFAP), but negative for Mts1 in the dorsal horn. One week after injury the level of nestin expression decreased and was undetectable after 3 months. Taken together, our data indicate that after dorsal root injury newly formed astrocytes in the degenerating white and grey matter first appear at the dorsal surface of the spinal cord from where some of them subsequently migrate ventrally, and differentiate into white- or grey-matter astrocytes.

  15. Differential effects of muscimol upon the firing frequency of large and small amplitude antidromic dorsal root action potentials in rat spinal cord in vitro.

    PubMed

    Bagust, J; Willis, W D

    2002-09-20

    The effects of bath applied muscimol upon spontaneous and evoked antidromic activity recorded from lumbar dorsal roots was investigated in hemisected, isolated preparations of rat spinal cord. In magnesium free medium containing 0.1 microM 4-aminopyridine, bursts of high amplitude (up to 1 mV), dorsal root reflexes were recorded. These were blocked by low concentrations of muscimol (2-5 microM). Higher concentrations (5-20 microM) of muscimol caused a concentration-dependent increase in the frequency of small amplitude (<200 microV) spontaneous dorsal root action potentials. The possibility that the large and small amplitude extracellular action potentials reflect activity in large and small diameter dorsal root axons, and that these respond in different ways to the GABA(A) agonist muscimol, is discussed.

  16. 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

  17. Aromatase inhibition exacerbates pain and reactive gliosis in the dorsal horn of the spinal cord of female rats caused by spinothalamic tract injury.

    PubMed

    Ghorbanpoor, Samar; Garcia-Segura, Luis Miguel; Haeri-Rohani, Ali; Khodagholi, Fariba; Jorjani, Masoumeh

    2014-11-01

    Central pain syndrome is characterized by severe and excruciating pain resulting from a lesion in the central nervous system. Previous studies have shown that estradiol decreases pain and that inhibitors of the enzyme aromatase, which synthesizes estradiol from aromatizable androgens, increases pain sensitivity. In this study we have assessed whether aromatase expression in the dorsal horns of the spinal cord is altered in a rat model of central pain syndrome, induced by the unilateral electrolytic lesion of the spinothalamic tract. Protein and mRNA levels of aromatase, as well as the protein and mRNA levels of estrogen receptors α and β, were increased in the dorsal horn of female rats after spinothalamic tract injury, suggesting that the injury increased estradiol synthesis and signaling in the dorsal horn. To determine whether the increased aromatase expression in this pain model may participate in the control of pain, mechanical allodynia thresholds were determined in both hind paws after the intrathecal administration of letrozole, an aromatase inhibitor. Aromatase inhibition enhanced mechanical allodynia in both hind paws. Because estradiol is known to regulate gliosis we assessed whether the spinothalamic tract injury and aromatase inhibition regulated gliosis in the dorsal horn. The proportion of microglia with a reactive phenotype and the number of glial fibrillary acidic protein-immunoreactive astrocytes were increased by the injury in the dorsal horn. Aromatase inhibition enhanced the effect of the injury on gliosis. Furthermore, a significant a positive correlation of mechanical allodynia and gliosis in the dorsal horn was detected. These findings suggest that aromatase is up-regulated in the dorsal horn in a model of central pain syndrome and that aromatase activity in the spinal cord reduces mechanical allodynia by controlling reactive gliosis in the dorsal horn.

  18. Effect of FGF-2 and sciatic nerve grafting on ChAT expression in dorsal root ganglia neurons of spinal cord transected rats.

    PubMed

    Guzen, Fausto Pierdoná; de Araújo, Dayane Pessoa; Lucena, Eudes Euler de Souza; de Morais, Hécio Henrique Araújo; Cavalcanti, José Rodolfo Lopes de Paiva; do Nascimento, Expedito Silva; Costa, Miriam Stela Maris de Oliveira; Cavalcante, Jeferson Sousa

    2016-03-11

    Neurotrophic factors and peripheral nerves are known to be good substrates for bridging CNS trauma. The involvement of fibroblast growth factor-2 (FGF-2) activation in the dorsal root ganglion (DRG) was examined following spinal cord injury in the rat. We evaluated whether FGF-2 increases the ability of a sciatic nerve graft to enhance neuronal plasticity, in a gap promoted by complete transection of the spinal cord. The rats were subjected to a 4mm-long gap at low thoracic level and were repaired with saline (Saline or control group, n=10), or fragment of the sciatic nerve (Nerve group, n=10), or fragment of the sciatic nerve to which FGF-2 (Nerve+FGF-2 group, n=10) had been added immediately after lesion. The effects of the FGF-2 and fragment of the sciatic nerve grafts on neuronal plasticity were investigated using choline acetyl transferase (ChAT)-immunoreactivity of neurons in the dorsal root ganglion after 8 weeks. Preservation of the area and diameter of neuronal cell bodies in dorsal root ganglion (DRG) was seen in animals treated with the sciatic nerve, an effect enhanced by the addition of FGF-2. Thus, the addition of exogenous FGF-2 to a sciatic nerve fragment grafted in a gap of the rat spinal cord submitted to complete transection was able to improve neuroprotection in the DRG. The results emphasized that the manipulation of the microenvironment in the wound might amplify the regenerative capacity of peripheral neurons.

  19. 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.

  20. 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

  1. Nerve growth factor (NGF) and diabetic neuropathy in the rat: morphological investigations of the sural nerve, dorsal root ganglion, and spinal cord.

    PubMed

    Unger, J W; Klitzsch, T; Pera, S; Reiter, R

    1998-09-01

    A number of functions for nerve growth factor (NGF) have been described over the past years, including its role for neuronal function and regeneration during toxic or metabolic neuropathies. In order to further assess the effects of NGF on the somatosensory system in diabetic neuropathy, the sural nerve, dorsal root ganglia (DRG), and dorsal horn of the spinal cord were investigated by morphological and quantitative methods in rats after 12 weeks of uncontrolled streptozotocin-induced diabetes mellitus. The results from our study suggest a twofold effect of NGF: (1) In sural nerve treatment with NGF (0.1 or 0.5 mg/kg) for 12 weeks was able to reverse distinct diabetes-related alterations in myelinated nerve fiber morphology, such as myelin thickness. These changes occurred in the entire myelinated population of sensory nerves and were not restricted to nociceptive nerve fibers. (2) The NGF effect on neurotransmitters of the sensory, nociceptive system was reflected by increased CGRP and substance P content in the DRG and in the dorsal horn of the spinal cord. No change of trkA receptor immunostaining was seen in DRGs of diabetic rats; however, a reduction of trkA immunoreactivity of DRG neurons was noted after long-term NGF treatment of healthy controls. The data demonstrate that NGF regulates a number of neuronal parameters along peripheral and central parts of the somatosensory pathway in the adult. This neurotrophic support may be essential for inducing functionally significant regenerative mechanisms in diabetic neuropathy.

  2. Spinal dorsal horn cell receptive field size is increased in adult rats following neonatal hindpaw skin injury.

    PubMed

    Torsney, Carole; Fitzgerald, Maria

    2003-07-01

    Local tissue damage in newborn rats can lead to changes in skin sensitivity that last into adulthood and this is likely to be due to plasticity of developing peripheral and central sensory connections. This study examines the functional connections of dorsal horn neurons in young and adult rats that have undergone local skin damage at birth. Newborn rat pups were halothane anaesthetised and received either a unilateral subcutaneous plantar injection of 1 % lambda-carrageenan or a unilateral plantar foot injury made by removal of 2 mm x 2 mm of skin. At 3 weeks, (postnatal day (P) 19-23) and 6 weeks (P40-44) in vivo extracellular recordings of single dorsal horn cells with plantar cutaneous receptive fields were made under urethane anaesthesia (2 g kg-1) and responses to mechanical and electrical stimulation of the skin were assessed. Following neonatal carrageenan inflammation, dorsal horn neuron properties and receptive field sizes at 3 weeks were the same as those of controls. In contrast, following neonatal skin injury, dorsal horn cell receptive field sizes were significantly greater than those of controls at 3 weeks (2.5-fold) and at 6 weeks (2.2-fold). Mechanical thresholds, mechanical response magnitudes and evoked responses to single and repeated A and C fibre stimulation remained unaffected. These results show that early skin injury can cause prolonged changes in central sensory connections that persist into adult life, long after the skin has healed. Enlarged dorsal horn neuron receptive field sizes provide a physiological mechanism for the persistent behavioural hypersensitivity that follows neonatal skin injury in rats and for the prolonged sensory changes reported in human infants after early pain and injury.

  3. Role of 5-HT1 receptor subtypes in the modulation of pain and synaptic transmission in rat spinal superficial dorsal horn

    PubMed Central

    Jeong, Hyo-Jin; Mitchell, Vanessa A; Vaughan, Christopher W

    2012-01-01

    BACKGROUND AND PURPOSE 5-HT receptor agonists have variable nociceptive effects within the spinal cord. While there is some evidence for 5-HT1A spinally-mediated analgesia, the role of other 5-HT1 receptor subtypes remains unclear. In the present study, we examined the spinal actions of a range of 5-HT1 agonists, including sumatriptan, on acute pain, plus their effect on afferent-evoked synaptic transmission onto superficial dorsal horn neurons. EXPERIMENTAL APPROACH For in vivo experiments, 5-HT agonists were injected via chronically implanted spinal catheters to examine their effects in acute mechanical and thermal pain assays using a paw pressure analgesymeter and a Hargreave's device. For in vitro experiments, whole-cell patch-clamp recordings of primary afferent-evoked glutamatergic EPSC were made from lamina II neurons in rat lumbar spinal slices. KEY RESULTS Intrathecal (i.t.) delivery of the 5-HT1A agonist R ± 8-OH-DPAT (30–300 nmol) produced a dose-dependent thermal, but not mechanical, analgesia. Sumatriptan and the 5-HT1B, 5-HT1D, 5-HT1F agonists CP93129, PNU109291 and LY344864 (100 nmol) had no effect on either acute pain assay. R ± 8-OH-DPAT (1 µM) and sumatriptan (3 µM) both reduced the amplitude of the evoked EPSC. In contrast, CP93129, PNU109291 and LY344864 (0.3–3 µM) had no effect on the evoked EPSC. The actions of both R ± 8-OH-DPAT and sumatriptan were abolished by the 5-HT1A antagonist WAY100635 (3 µM). CONCLUSIONS AND IMPLICATIONS These findings indicate that the 5-HT1A receptor subtype predominantly mediates the acute antinociceptive and cellular actions of 5-HT1 ligands within the rat superficial dorsal horn. PMID:21950560

  4. Roles of dorsal column pathway and transient receptor potential vanilloid type 1 in augmentation of cerebral blood flow by upper cervical spinal cord stimulation in rats.

    PubMed

    Yang, X; Farber, J P; Wu, M; Foreman, R D; Qin, C

    2008-04-09

    Clinical and basic studies have indicated that upper cervical spinal cord stimulation (cSCS) significantly increases cerebral blood flow (CBF), but the mechanisms are incompletely understood. This investigation was conducted to differentiate between stimulation of dorsal column fibers and upper cervical spinal cord cell bodies in cSCS-induced increases in CBF and decreases in cerebrovascular resistance (CVR). cSCS (50 Hz, 0.2 ms, 1 min) was applied on the left C1-C2 dorsal column of pentobarbital anesthetized, ventilated and paralyzed male rats. Laser Doppler flowmetry probes were placed bilaterally over the parietal cortex, and arterial pressure was monitored. cSCS at 30%, 60%, and 90% of motor threshold (MT) produced vasodilation bilaterally in cerebral cortices. Subsequently, cSCS was applied at 90% MT, and ipsilateral responses were recorded. Ibotenic acid (0.3 mg/ml, 0.1 ml) placed on dorsal surface of C1-C2 (n=7) to suppress cell body activity, did not affect cSCS-induced %DeltaCBF (42.5+/-8.1% vs. 36.8+/-7.1%, P>0.05) and %DeltaCVR (-19.4+/-4.2% vs. -15.2+/-5.6%, P>0.05). However, bilateral transection of the dorsal column at rostral C1 (n=8) abolished cSCS-induced changes in CBF and CVR. Also, rostral C1 transection (n=7) abolished cSCS-induced changes in CBF and CVR. Resinferatoxin (RTX), an ultrapotent transient receptor potential vanilloid type 1 (TRPV1) agonist, was used to inactivate TRPV1 containing nerve fibers/cell bodies. RTX (2 microg/ml, 0.1 ml) placed on the C1-C2 spinal cord (n=7) did not affect cSCS-induced %DeltaCBF (60.2+/-8.1% vs. 46.3+/-7.7%, P>0.05) and %DeltaCVR (-25.5+/-3.5% vs. -21.4+/-8.9%, P>0.05). However, i.v. RTX (2 microg/kg, n=9) decreased cSCS-induced %DeltaCBF from 65.0+/-9.5% to 27.4+/-7.2% (P<0.05) and %DeltaCVR from -28.0+/-7.6% to -14.8+/-4.2% (P<0.05). These results indicated that cSCS-increases in CBF and decreases in CVR occurred via rostral spinal dorsal column fibers and did not depend upon C1-C2 cell bodies. Also

  5. 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

    2013-09-05

    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.

  6. Pregabalin alters nociceptive behavior and expression level of P2X3 receptor in the spinal dorsal horn in a rat model induced by chronic compression of the dorsal root ganglion.

    PubMed

    Yu, Jianfeng; Fu, Peng; Zhang, Yan; Liu, Shuzhen; Cui, Donghong

    2013-12-01

    P2X3 receptors are present in the spinal dorsal horn (SDH) and play an essential role in the regulation of nociception and pain. Pregabalin (PGB) has been used as a new antiepileptic drug in the treatment of neuropathic pain. However, it is unclear whether PGB-induced analgesia was associated with the P2X3 receptor in SDH. Here, rats were randomly divided into four groups (n = 12 per group), including 2 sham operation groups, which was treated by normal saline (Sham + NS group) or PGB (Sham + PGB group), other 2 groups with chronic compression of the dorsal root ganglion, a normal saline-treated CCD group (CCD+NS group), and a PGB-treated CCD group (CCD + PGB group). A rat model of neuropathic pain was used by compressing the right L4 and L5 dorsal root ganglia. Each group was evaluated using the mechanical withdrawal threshold (MWT). The mRNA and protein levels of the P2X3 receptor in the ipsilateral SDH were measured by RT-PCR, western blot, and immunofluorescence on 14 day after CCD operation. CCD rats showed the highest mechanical hyperalgesia and the lowest pain threshold in the four groups. Simultaneously, CCD rats showed higher P2X3 mRNA and protein expression in ipsilateral side of the SDH than the sham operation rats. However, the MWT was increased and expression of P2X3 mRNA and protein in the ipsilateral SDH in CCD rats was decreased 3 days after PGB treatment. Thus, PGB may partially reverse mechanical hyperalgesia in CCD rats by inhibiting P2X3 receptor expression in the ipsilateral SDH.

  7. Effective gene expression in the rat dorsal root ganglia with a non-viral vector delivered via spinal nerve injection

    PubMed Central

    Chang, Ming-Fong; Hsieh, Jung-Hsien; Chiang, Hao; Kan, Hung-Wei; Huang, Cho-Min; Chellis, Luke; Lin, Bo-Shiou; Miaw, Shi-Chuen; Pan, Chun-Liang; Chao, Chi-Chao; Hsieh, Sung-Tsang

    2016-01-01

    Delivering gene constructs into the dorsal root ganglia (DRG) is a powerful but challenging therapeutic strategy for sensory disorders affecting the DRG and their peripheral processes. The current delivery methods of direct intra-DRG injection and intrathecal injection have several disadvantages, including potential injury to DRG neurons and low transfection efficiency, respectively. This study aimed to develop a spinal nerve injection strategy to deliver polyethylenimine mixed with plasmid (PEI/DNA polyplexes) containing green fluorescent protein (GFP). Using this spinal nerve injection approach, PEI/DNA polyplexes were delivered to DRG neurons without nerve injury. Within one week of the delivery, GFP expression was detected in 82.8% ± 1.70% of DRG neurons, comparable to the levels obtained by intra-DRG injection (81.3% ± 5.1%, p = 0.82) but much higher than those obtained by intrathecal injection. The degree of GFP expression by neurofilament(+) and peripherin(+) DRG neurons was similar. The safety of this approach was documented by the absence of injury marker expression, including activation transcription factor 3 and ionized calcium binding adaptor molecule 1 for neurons and glia, respectively, as well as the absence of behavioral changes. These results demonstrated the efficacy and safety of delivering PEI/DNA polyplexes to DRG neurons via spinal nerve injection. PMID:27748450

  8. Spinal nerve ligation decreases γ-aminobutyric acidB receptors on specific populations of immunohistochemically identified neurons in L5 dorsal root ganglion of the rat.

    PubMed

    Engle, Mitchell P; Merrill, Michelle A; Marquez De Prado, Blanca; Hammond, Donna L

    2012-06-01

    This study examined the distribution of γ-aminobutyric acid (GABA)(B) receptors on immunohistochemically identified neurons, and levels of GABA(B(1)) and GABA(B(2)) mRNA, in the L4 and L5 dorsal root ganglia (DRG) of the rat in the absence of injury and 2 weeks after L5 spinal nerve ligation. In uninjured DRG, GABA(B(1)) immunoreactivity colocalized exclusively with the neuronal marker (NeuN) and did not colocalize with the satellite cell marker S-100. The GABA(B(1)) subunit colocalized to >97% of DRG neurons immunoreactive (IR) for neurofilament 200 (N52) or calcitonin gene-related peptide (CGRP), or labeled by isolectin B4 (IB4). Immunoreactivity for GABA(B(2)) was not detectable. L5 spinal nerve ligation did not alter the number of GABA(B(1)) -IR neurons or its colocalization pattern in the L4 DRG. However, ligation reduced the number of GABA(B(1)) -IR neurons in the L5 DRG by ≈38% compared with sham-operated and naïve rats. Specifically, ligation decreased the number of CGRP-IR neurons in the L5 DRG by 75%, but did not decrease the percent colocalization of GABA(B(1)) in those that remained. In the few IB4-positive neurons that remained in the L5 DRG, colocalization of GABA(B(1)) -IR decreased to 75%. Ligation also decreased levels of GABA(B(1)) and GABA(B(2)) mRNA in the L5, but not the L4 DRG compared with sham-operated or naïve rats. These findings indicate that the GABA(B) receptor is positioned to presynaptically modulate afferent transmission by myelinated, unmyelinated, and peptidergic afferents in the dorsal horn. Loss of GABA(B) receptors on primary afferent neurons may contribute to the development of mechanical allodynia after L5 spinal nerve ligation.

  9. Endogenous Interleukin-1β in Neuropathic Rats Enhances Glutamate Release from the Primary Afferents in the Spinal Dorsal Horn through Coupling with Presynaptic N-Methyl-d-aspartic Acid Receptors*♦

    PubMed Central

    Yan, Xisheng; Weng, Han-Rong

    2013-01-01

    Excessive activation of glutamate receptors and overproduction of proinflammatory cytokines, including interleukin-1β (IL-1β) in the spinal dorsal horn, are key mechanisms underlying the development and maintenance of neuropathic pain. In this study, we investigated the mechanisms by which endogenous IL-1β alters glutamatergic synaptic transmission in the spinal dorsal horn in rats with neuropathic pain induced by ligation of the L5 spinal nerve. We demonstrated that endogenous IL-1β in neuropathic rats enhances glutamate release from the primary afferent terminals and non-NMDA glutamate receptor activities in postsynaptic neurons in the spinal dorsal horn. Myeloid differentiation primary response protein 88 (MyD88) is a mediator used by IL-1β to enhance non-NMDA glutamate receptor activities in postsynaptic neurons in the spinal dorsal horn. Presynaptic NMDA receptors are effector receptors used by the endogenous IL-1β to enhance glutamate release from the primary afferents in neuropathic rats. This is further supported by the fact that NMDA currents recorded from small neurons in the dorsal root ganglion of normal rats are potentiated by exogenous IL-1β. Furthermore, we provided evidence that functional coupling between IL-1β receptors and presynaptic NMDA receptors at the primary afferent terminals is mediated by the neutral sphingomyelinase/ceramide signaling pathway. Hence, functional coupling between IL-1β receptors and presynaptic NMDA receptors at the primary afferent terminals is a crucial mechanism leading to enhanced glutamate release and activation of non-NMDA receptors in the spinal dorsal horn neurons in neuropathic pain conditions. Interruption of such functional coupling could be an effective approach for the treatment of neuropathic pain. PMID:24003233

  10. 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

  11. Cortical PKC inhibition promotes axonal regeneration of the corticospinal tract and forelimb functional recovery after cervical dorsal spinal hemisection in adult rats.

    PubMed

    Wang, Xiaofei; Hu, Jianguo; She, Yun; Smith, George M; Xu, Xiao-Ming

    2014-11-01

    Our previous study shows that conventional protein kinases C (cPKCs) are key signaling mediators that are activated by extracellular inhibitory molecules. Inhibition of cPKC by intrathecal infusion of a cPKC inhibitor, GÖ6976, into the site of dorsal hemisection (DH) induces regeneration of lesioned dorsal column sensory, but not corticospinal tract (CST), axons. Here, we investigated whether a direct cortical delivery of GÖ6976 into the soma of corticospinal neurons promotes regeneration of CST and the recovery of forelimb function in rats with cervical spinal cord injuries. We report that cortical delivery of GÖ6976 reduced injury-induced activation of conventional PKCα and PKCβ1 in CST neurons, promoted regeneration of CST axons through and beyond a cervical DH at C4, formed new synapses on target neurons caudal to the injury, and enhanced forelimb functional recovery in adult rats. When combined with lenti-Chondroitinase ABC treatment, cortical administration of GÖ6976 promoted even greater CST axonal regeneration and recovery of forelimb function. Thus, this study has demonstrated a novel strategy that can promote anatomical regeneration of damaged CST axons and partial recovery of forelimb function. Importantly, such an effect is critically dependent on the efficient blockage of injury-induced PKC activation in the soma of layer V CST neurons.

  12. Activation of transient receptor potential vanilloid 2-expressing primary afferents stimulates synaptic transmission in the deep dorsal horn of the rat spinal cord and elicits mechanical hyperalgesia.

    PubMed

    Petitjean, Hugues; Hugel, Sylvain; Barthas, Florent; Bohren, Yohann; Barrot, Michel; Yalcin, Ipek; Schlichter, Rémy

    2014-10-01

    Probenecid, an agonist of transient receptor vanilloid (TRPV) type 2, was used to evaluate the effects of TRPV2 activation on excitatory and inhibitory synaptic transmission in the dorsal horn (DH) of the rat spinal cord and on nociceptive reflexes induced by thermal heat and mechanical stimuli. The effects of probenecid were compared with those of capsaicin, a TRPV1 agonist. Calcium imaging experiments on rat dorsal root ganglion (DRG) and DH cultures indicated that functional TRPV2 and TRPV1 were expressed by essentially non-overlapping subpopulations of DRG neurons, but were absent from DH neurons and DH and DRG glial cells. Pretreatment of DRG cultures with small interfering RNAs against TRPV2 suppressed the responses to probenecid. Patch-clamp recordings from spinal cord slices showed that probenecid and capsaicin increased the frequencies of spontaneous excitatory postsynaptic currents (sEPSCs) and spontaneous inhibitory postsynaptic currents in a subset of laminae III-V neurons. In contrast to capsaicin, probenecid failed to stimulate synaptic transmission in lamina II. Intrathecal or intraplantar injections of probenecid induced mechanical hyperalgesia/allodynia without affecting nociceptive heat responses. Capsaicin induced both mechanical hyperalgesia/allodynia and heat hyperalgesia. Activation of TRPV1 or TRPV2 in distinct sets of primary afferents increased the sEPSC frequencies in a largely common population of DH neurons in laminae III-V, and might underlie the development of mechanical hypersensitivity following probenecid or capsaicin treatment. However, only TRPV1-expressing afferents facilitated excitatory and/or inhibitory transmission in a subpopulation of lamina II neurons, and this phenomenon might be correlated with the induction of thermal heat hyperalgesia.

  13. Roles of dorsal column pathway and TRPV1 in augmentation of cerebral blood flow by upper cervical spinal cord stimulation in rats

    PubMed Central

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

    2008-01-01

    Clinical and basic studies have indicated that upper cervical spinal cord stimulation (cSCS) significant increases cerebral blood flow (CBF), but the mechanisms are incompletely understood. This investigation was conducted to differentiate between stimulation of dorsal column fibers and upper cervical spinal cord cell bodies in cSCS-induced increases in CBF and decreases in cerebral vascular resistance (CVR). cSCS (50 Hz, 0.2 ms, 1 min) was applied on the left C1-C2 dorsal column n pentobarbital anesthetized, ventilated and paralyzed male rats. Laser Doppler flowmetry probes were placed bilaterally over the parietal cortex, and arterial pressure was monitored. cSCS at 30%, 60%, and 90% of motor threshold (MT) produced vasodilation bilaterally in cerebral cortices. Subsequently, cSCS was applied at 90% MT, and ipsilateral responses were recorded. Ibotenic acid (0.3mg/ml, 0.1ml) placed on dorsal surface of C1-C2 (n=7) to suppress cell body activity, did not affect cSCS-induced %□CBF (42.5±8.1% vs 36.8±7.1%, P>0.05□and %□CVR (−19.4±4.2% vs −15.2±5.6%, P>0.05). However, bilateral transection of the dorsal column at rostral C1 (n=8) abolished cSCS-induced changes in CBF and CVR. Also, rostral C1 transection (n=7) abolished cSCS-induced changes in CBF and CVR. Resinferatoxin (RTX), an ultra potent TRPV1 agonist, was used to inactivate TRPV1 containing nerve fibers / cell bodies. RTX (2 µg/ml□0.1ml) placed on the C1-C2 spinal cord (n=7) did not affect cSCS-induced %ΔCBF (60.2±8.1% vs 46.3±7.7%, P>0.05) and %ΔCVR (−25.5±3.5% vs −21.4±8.9%, P>0.05). However, intravenous RTX (2 µg/kg, n=9) decreased cSCS-induced %ΔCBF from 65.0±9.5% to 27.4±7.2% (P<0.05) and %ΔCVR from −28.0±7.6% to −14.8±4.2% (P<0.05). These results indicated that cSCS-increases in CBF and decreases in CVR occurred via rostral spinal dorsal column fibers and did not depend upon C1-C2 cell bodies. Also, our results suggested that cerebral but not spinal TRPV1 was

  14. 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.

  15. Intrathecal baclofen, a GABAB receptor agonist, inhibits the expression of p-CREB and NR2B in the spinal dorsal horn in rats with diabetic neuropathic pain.

    PubMed

    Liu, Peng; Guo, Wen-Ya; Zhao, Xiao-Nan; Bai, Hui-Ping; Wang, Qian; Wang, Xiu-Li; Zhang, Ying-Ze

    2014-08-01

    This study aimed to investigate the effect of baclofen, a γ-aminobutyric acid B (GABAB) receptor agonist, on the expression of p-CREB and NR2B in the spinal dorsal horn of rats with diabetic neuropathic pain (DNP). The DNP rats, which were successfully induced with streptozocin, were distributed among 3 groups that were treated with saline (D1 group), baclofen (D2 group), or CGP55845 + baclofen (D3 group) continuously for 4 days. The rats induced with saline and subsequently treated with saline were used as controls (C group). The times for the paw withdrawal threshold and thermal withdrawal latency of the D1 group were lower than those for the C group, and were significantly increased after baclofen treatment, but not when GABA receptor was pre-blocked with CGP55845 (D3 group). Increased protein expression levels of NR2B and p-CREB and mRNA levels of NR2B were found in the D1 group when compared with the controls. Baclofen treatment significantly suppressed their expression, bringing it close to the levels of controls. However, in the D3 group, the expression of p-CREB and NR2B were still significantly higher than that of the controls. Activation of GABAB receptor by baclofen attenuates diabetic neuropathic pain, which may partly be accomplished via down-regulating the expression of p-CREB and NR2B.

  16. TRPA1 in the spinal dorsal horn is involved in post-inflammatory visceral hypersensitivity: in vivo study using TNBS-treated rat model

    PubMed Central

    Li, Qian; Guo, Cheng-Hao; Chowdhury, Mohammed Ali; Dai, Tao-Li; Han, Wei

    2016-01-01

    Introduction The transient receptor potential ankyrin-1 (TRPA1) channel, a pain transducer and amplifier, is drawing increasing attention in the field of visceral hypersensitivity, commonly seen in irritable bowel syndrome and inflammatory bowel disease. However, the role of TRPA1 in visceral nociception during post-inflammatory states is not well defined. Here, we explore the correlation between TRPA1 expression in the spinal dorsal horn (SDH) and persistent post-inflammatory visceral hypersensitivity. Methods We injected rats intracolonically with 2,4,6-trinitrobenzene sulfonic acid (TNBS) or vehicle (n=12 per group). Post-inflammatory visceral hypersensitivity was assessed by recording the electromyographic activity of the external oblique muscle in response to colorectal distension. TRPA1 expression and distribution in the spinal cord and colon were examined by Western blotting and immunohistochemistry. Results Animals exposed to TNBS had more abdominal contractions than vehicle-injected controls (P<0.05), which corresponded to a lower nociceptive threshold. Expression of TRPA1 in the SDH (especially in the substantia gelatinosa) and the colon was significantly greater in the TNBS-treated group than in controls (P<0.05). In the SDH, the number of TRPA1-immunopositive neurons was 25.75±5.12 in the control group and 34.25±7.89 in the TNBS-treated group (P=0.023), and integrated optical density values of TRPA1 in the control and TNBS-treated groups were 14,544.63±6,525.54 and 22,532.75±7,608.11, respectively (P=0.041). Conclusion Our results indicate that upregulation of TRPA1 expression in the SDH is associated with persistent post-inflammatory visceral hypersensitivity in the rat and provides insight into potential therapeutic targets for the control of persistent visceral hypersensitivity. PMID:27980434

  17. Postnatal Excitability Development and Innervation by Functional Transient Receptor Potential Vanilloid 1 (TRPV1) Terminals in Neurons of the Rat Spinal Sacral Dorsal Commissural Nucleus: an Electrophysiological Study.

    PubMed

    Yang, Kun

    2016-11-01

    The sacral dorsal commissural nucleus (SDCN) in the spinal cord receives both somatic and visceral primary afferents. Transient receptor potential vanilloid 1 (TRPV1) channels are preferentially expressed in certain fine primary afferents. However, knowledge of the SDCN neurons postnatal excitability development and their contacts with TRPV1 fibers remains elusive. Here, whole-cell recordings were conducted in spinal cord slices to evaluate the postnatal development of SDCN neurons and their possible contacts with functional TRPV1-expressing terminals. SDCN neurons in neonatal (postnatal day (P) 1-2), young (P8-10), and adult rats (P35-40) have different electrophysiological properties. SDCN neurons in neonatal rats have higher frequency of spontaneous firing, higher resting membrane potential, and lower presynaptic glutamate release probability. However, no difference in quantal release was found. At all developmental stages, TRPV1 activation with the selective agonist capsaicin increases glutamate release in the presence of tetrodotoxin, which blocks action potential-dependent and polysynaptic neurotransmission, indicating that functional TRPV1 fibers innervate SDCN neurons directly. Capsaicin-induced presynaptic glutamate release onto SDCN neurons depends on external Ca(2+) influx through TRPV1 channels; voltage-dependent calcium channels had a slighter impact. In contrast, capsaicin blocked C fiber-evoked synaptic transmission, indicating that TRPV1 activation has opposite effects on spontaneous asynchronous and action potential-dependent synchronous glutamate release. These data indicate that excitability of SDCN neurons undergoes a developmental shift, and these neurons receive functional TRPV1 terminals from early postnatal stage. The opposite action of capsaicin on asynchronous and synchronous glutamate release should be taken into account when TRPV1 channels are considered as therapeutic targets.

  18. 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

    2015-06-04

    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

  19. Numbers, Densities, and Colocalization of AMPA- and NMDA-Type Glutamate Receptors at Individual Synapses in the Superficial Spinal Dorsal Horn of Rats

    PubMed Central

    Fukazawa, Yugo; Eördögh, Mária; Muszil, Dóra; Molnár, Elek; Itakura, Makoto; Takahashi, Masami; Shigemoto, Ryuichi

    2008-01-01

    Ionotropic glutamate receptors play important roles in spinal processing of nociceptive sensory signals and induction of central sensitization in chronic pain. Here we applied highly sensitive freeze-fracture replica labeling to laminae I–II of the spinal dorsal horn of rats and investigated the numbers, densities, and colocalization of AMPA- and NMDA-type glutamate receptors at individual postsynaptic membrane specializations with a high resolution. All glutamatergic postsynaptic membranes in laminae I–II expressed AMPA receptors, and most of them (96%) were also immunoreactive for the NR1 subunit of NMDA receptors. The numbers of gold particles for AMPA and NMDA receptors at individual postsynaptic membranes showed a linear correlation with the size of postsynaptic membrane specializations and varied in the range of 8–214 and 5–232 with median values of 37 and 28, whereas their densities varied in the range of 325–3365/μm2 and 102–2263/μm2 with median values of 1115/μm2 and 777/μm2, respectively. Virtually all (99%) glutamatergic postsynaptic membranes expressed GluR2, and most of them (87%) were also immunoreactive for GluR1. The numbers of gold particles for pan-AMPA, NR1, and GluR2 subunits showed a linear correlation with the size of postsynaptic surface areas. Concerning GluR1, there may be two populations of synapses with high and low GluR1 densities. In synapses larger than 0.1 μm2, GluR1 subunits were recovered in very low numbers. Differential expression of GluR1 and GluR2 subunits suggests regulation of AMPA receptor subunit composition by presynaptic mechanism. PMID:18815255

  20. Involvement of peripheral ionotropic glutamate receptors in activation of cutaneous branches of spinal dorsal rami following antidromic electrical stimulation of adjacent afferent nerves in rats.

    PubMed

    Cao, Dong-Yuan; You, Hao-Jun; Zhao, Yan; Guo, Yuan; Wang, Hui-Sheng; Arendt-Nielsen, Lars; Wang, Hui-Ling; Zhang, Qi

    2007-04-02

    The aim of the present study was to investigate the role of peripheral ionotropic glutamate receptors in the process of signal transmission between adjacent different peripheral sensory nerves. The T9 and T10 cutaneous branches of spinal dorsal rami were dissociated and cut proximally in pentobarbital anesthetized rats. Eighty-seven single afferents from T10 nerve filaments were recorded and characterized by assessing their spontaneous activities. Following 30 s antidromic electrical stimulation (intensity: 1 mA; duration: 0.5 ms; frequency: 20 Hz) of T9 cutaneous branches, the spontaneous activities of Abeta, Adelta and C fibers of T10 nerve were significantly enhanced from 2.00+/-0.34, 2.42+/-0.33, and 2.19+/-0.32 impulses/min to 4.31+/-0.58, 5.22+/-0.55, and 5.27+/-0.69 impulses/min, respectively (n=29 for each type, P<0.05). These enhanced spontaneous discharges of T10 nerve were significantly blocked by local treatment of its receptive field with either N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 or non-NMDA receptor antagonist DNQX (0.1 mM, 10 microl for each drug) (P<0.05). These results suggest that peripheral ionotropic glutamate receptors are involved in the activation of peripheral nerves following the antidromic stimulation of adjacent afferents from different spinal segments. We further provide the direct evidence that neurotransmitters released from adjacent peripheral nerves may also contribute to the occurrence of allodynia as well as secondary hyperalgesia during the pathological nociception.

  1. In vivo effects of L1 coating on inflammation and neuronal health at the electrode/tissue interface in rat spinal cord and dorsal root ganglion

    PubMed Central

    Kolarcik, Christi L.; Bourbeau, Dennis; Azemi, Erdrin; Rost, Erika; Zhang, Ling; Lagenaur, Carl F.; Weber, Douglas J.; Cui, X. Tracy

    2012-01-01

    The spinal cord (SC) and dorsal root ganglion (DRG) are target implantation regions for neural prosthetics, but the tissue-electrode interface in these regions is not well-studied. To improve our understanding of these locations, we characterized the tissue reactions around implanted electrodes. L1, an adhesion molecule shown to maintain neuronal density and reduce gliosis in brain tissue, was then evaluated in SC and DRG implants. Following L1 immobilization onto neural electrodes, the bioactivities of the coatings were verified in vitro using neuron, astrocyte and microglia cultures. Non-modified and L1-coated electrodes were implanted into adult rats for 1 or 4 weeks. Hematoxylin and eosin staining along with cell-type specific antibodies were used to characterize the tissue response. In the SC and DRG, cells aggregated at the electrode-tissue interface. Microglia staining was more intense around the implant site and decreased with distance from the interface. Neurofilament staining in both locations was decreased or absent around the implant when compared to surrounding tissue. With L1, neurofilament staining was significantly increased while neuronal cell death decreased. Our results indicate that L1-modified electrodes may result in an improved chronic neural interface and will be evaluated in recording and stimulation studies. PMID:22750248

  2. 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

  3. The effect of botulinum neurotoxin A on sciatic nerve injury-induced neuroimmunological changes in rat dorsal root ganglia and spinal cord.

    PubMed

    Mika, J; Rojewska, E; Makuch, W; Korostynski, M; Luvisetto, S; Marinelli, S; Pavone, F; Przewlocka, B

    2011-02-23

    Botulinum neurotoxin serotype A (BoNT/A) acts by cleaving synaptosome-associated-protein-25 (SNAP-25) in nerve terminals to inhibit neuronal release and shows long-lasting antinociceptive action in neuropathic pain. However, its precise mechanism of action remains unclear. Our study aimed to characterize BoNT/A-induced neuroimmunological changes after chronic constriction injury (CCI) of the sciatic nerve. In the ipsilateral lumbar spinal cords of CCI-exposed rats, the mRNA of microglial marker (complement component 1q, C1q), astroglial marker (glial fibrillary acidic protein, GFAP), and prodynorphin were upregulated, as measured by reverse transcription-polymerase chain reaction (RT-PCR). No changes appeared in mRNA for proenkephalin, pronociceptin, or neuronal and inducible nitric oxide synthase (NOS1 and NOS2, respectively). In the dorsal root ganglia (DRG), an ipsilateral upregulation of prodynorphin, pronociceptin, C1q, GFAP, NOS1 and NOS2 mRNA and a downregulation of proenkephalin mRNA were observed. A single intraplantar BoNT/A (75 pg/paw) injection induced long-lasting antinociception in this model. BoNT/A diminished the injury-induced ipsilateral spinal upregulation of C1q mRNA. In the ipsilateral DRG a significant decrease of C1q-positive cell activation and of the upregulation of prodynorphin, pronociceptin and NOS1 mRNA was also observed following BoNT/A admistration. BoNT/A also diminished the injury-induced upregulation of SNAP-25 expression in both structures. We provide evidence that BoNT/A impedes injury-activated neuronal function in structures distant from the injection site, which is demonstrated by its influence on NOS1, prodynorphin and pronociceptin mRNA levels in the DRG. Moreover, the silence of microglia/macrophages after BoNT/A administration could be secondary to the inhibition of neuronal activity, but this decrease in neuroimmune interactions could be the key to the long-lasting BoNT/A effect on neuropathic pain.

  4. Effects of DA-9701, a Novel Prokinetic Agent, on Phosphorylated Extracellular Signal-Regulated Kinase Expression in the Dorsal Root Ganglion and Spinal Cord Induced by Colorectal Distension in Rats

    PubMed Central

    Lee, Sang Pyo; Lee, Kang Nyeong; Lee, Hang Lak; Jun, Dae Won; Yoon, Byung Chul; Choi, Ho Soon; Hwang, Se Jin; Lee, Seo Eun

    2014-01-01

    Background/Aims DA-9701, a standardized extract of Pharbitis Semen and Corydalis Tuber, is a new prokinetic agent that exhibits an analgesic effect on the abdomen. We investigated whether DA-9701 affects visceral pain induced by colorectal distension (CRD) in rats. Methods A total of 21 rats were divided into three groups: group A (no CRD+no drug), group B (CRD+no drug), and group C (CRD+DA-9701). Expression of pain-related factors, substance P (SP), c-fos, and phosphorylated extracellular signal-regulated kinase (p-ERK) in the dorsal root ganglion (DRG) and spinal cord was determined by immunohistochemical staining and Western blotting. Results The proportions of neurons in the DRG and spinal cord expressing SP, c-fos, and p-ERK were higher in group B than in group A. In the group C, the proportion of neurons in the DRG and spinal cord expressing p-ERK was lower than that in group B. Western blot results for p-ERK in the spinal cord indicated a higher level of expression in group B than in group A and a lower level of expression in group C than in group B. Conclusions DA-9701 may decrease visceral pain via the downregulation of p-ERK in the DRG and spinal cord. PMID:24672654

  5. Morphological characterization of spinal cord dorsal horn lamina I neurons projecting to the parabrachial nucleus in the rat.

    PubMed

    Almarestani, L; Waters, S M; Krause, J E; Bennett, G J; Ribeiro-da-Silva, A

    2007-09-20

    Many Rexed's lamina I neurons are nociceptive and project to the brain. Lamina I projection neurons can be classified as multipolar, fusiform, or pyramidal, based on cell body shape and characteristics of their proximal dendrites in the horizontal plane. There is also evidence that both multipolar and fusiform cells are nociceptive and pyramidal neurons nonnociceptive. In this investigation we identified which types of lamina I neurons belong to the spinoparabrachial tract in the rat and characterized them regarding the presence or absence of neurokinin-1 receptor (NK-1r) immunoreactivity. For this, cholera toxin subunit B (CTb), conjugated to a fluorescent marker was injected unilaterally into the parabrachial nucleus. Sections were additionally stained for the detection of NK-1r immunoreactivity and were examined using fluorescence and confocal microscopy. Serial confocal optical sections and 3D reconstructions were obtained for a considerable number of neurons per animal. Using immunofluorescence, we assessed the proportion of lamina I neurons belonging to the spinoparabrachial (SPB) tract and/or expressing NK-1r. The relative distribution of neurons belonging to the SPB tract was: 38.7% multipolar, 36.8% fusiform, 22.7% pyramidal, and 1.9% unclassified. Most of the SPB neurons expressing NK-1r were either multipolar or fusiform. Pyramidal SPB neurons were seldom immunoreactive for NK-1r, an observation that provides further support to the concept that most lamina I projection neurons of the pyramidal type are nonnociceptive. In addition, our study provides further evidence that these distinct morphological types of neurons differ in their phenotypic properties, but not in their projection patterns.

  6. Activation of Mas oncogene-related gene (Mrg) C receptors enhances morphine-induced analgesia through modulation of coupling of μ-opioid receptor to Gi-protein in rat spinal dorsal horn.

    PubMed

    Wang, D; Chen, T; Zhou, X; Couture, R; Hong, Y

    2013-12-03

    Mas oncogene-related gene (Mrg) G protein-coupled receptors are exclusively expressed in small-sized neurons in trigeminal and dorsal root ganglia (DRG) in mammals. The present study investigated the effect of MrgC receptor activation on morphine analgesic potency and addressed its possible mechanisms. Intrathecal (i.t.) administration of the specific MrgC receptor agonist bovine adrenal medulla 8-22 (BAM8-22, 3 nmol) increased morphine-induced analgesia and shifted the morphine dose-response curve to the left in rats. Acute morphine (5 μg) reduced the coupling of μ-opioid receptors (MORs) to Gi-, but not Gs-, protein in the spinal dorsal horn. The i.t. BAM8-22 (3 nmol) prevented this change of G-protein repertoire while the inactive MrgC receptor agonist BAM8-18 (3 nmol, i.t.) failed to do so. A double labeling study showed the co-localization of MrgC and MORs in DRG neurons. The i.t. BAM8-22 also increased the coupling of MORs to Gi-protein and recruited Gi-protein from cytoplasm to the cell membrane in the spinal dorsal horn. Application of BAM8-22 (10nM) in the cultured ganglion explants for 30 min increased Gi-protein mRNA, but not Gs-protein mRNA. The present study demonstrated that acute administration of morphine inhibited the repertoire of MOR/Gi-protein coupling in the spinal dorsal horn in vivo. The findings highlight a novel mechanism by which the activation of MrgC receptors can modulate the coupling of MORs with Gi-protein to enhance morphine-induced analgesia. Hence, adjunct treatment of MrgC agonist BAM8-22 may be of therapeutic value to relieve pain.

  7. Antidromic discharges of dorsal root afferents in the neonatal rat.

    PubMed

    Vinay, L; Brocard, F; Fellippa-Marques, S; Clarac, F

    1999-01-01

    Presynaptic inhibition of primary afferents can be evoked from at least three sources in the adult animal: 1) by stimulation of several supraspinal structures; 2) by spinal reflex action from sensory inputs; or 3) by the activity of spinal locomotor networks. The depolarisation in the intraspinal afferent terminals which is due, at least partly, to the activation of GABA(A) receptors may be large enough to reach firing threshold and evoke action potentials that are antidromically conducted into peripheral nerves. Little is known about the development of presynaptic inhibition and its supraspinal control during ontogeny. This article, reviewing recent experiments performed on the in vitro brainstem/spinal cord preparation of the neonatal rat, demonstrates that a similar organisation is present, to some extent, in the new-born rat. A spontaneous activity consisting of antidromic discharges can be recorded from lumbar dorsal roots. The discharges are generated by the underlying afferent terminal depolarizations reaching firing threshold. The number of antidromic action potentials increases significantly in saline solution with chloride concentration reduced to 50% of control. Bath application of the GABA(A) receptor antagonist, bicuculline (5-10 microM) blocks the antidromic discharges almost completely. Dorsal root discharges are therefore triggered by chloride-dependent GABA(A) receptor-mediated mechanisms; 1) activation of descending pathways by stimulation delivered to the ventral funiculus (VF) of the spinal cord at the C1 level; 2) activation of sensory inputs by stimulation of a neighbouring dorsal root; or 3) pharmacological activation of the central pattern generators for locomotion evokes antidromic discharges in dorsal roots. VF stimulation also inhibited the response to dorsal root stimulation. The time course of this inhibition overlapped with that of the dorsal root discharge suggesting that part of the inhibition of the monosynaptic reflex may be

  8. Endomorphins: localization, release and action on rat dorsal horn neurons.

    PubMed

    Dun, N J; Dun, S L; Wu, S Y; Williams, C A; Kwok, E H

    2000-01-01

    Endomorphin (Endo) 1 and 2, two tetrapeptides isolated from the bovine and human brain, have been proposed to be the endogenous ligand for the mu-opiate receptor. A multi-disciplinary study was undertaken to address the issues of localization, release and biological action of Endo with respect to the rat dorsal horn. First, immunohistochemical studies showed that Endo-1- or Endo-2-like immunoreactivity (Endo-1- or Endo-2-LI) is selectively expressed in fiber-like elements occupying the superficial layers of the rat dorsal horn, which also exhibit a high level of mu-opiate receptor immunoreactivity. Second, release of immunoreactive Endo-2-like substances (irEndo) from the in vitro rat spinal cords upon electrical stimulation of dorsal root afferent fibers was detected by the immobilized antibody microprobe technique. The site of release corresponded to laminae I and II where the highest density of Endo-2-LI fibers was localized. Lastly, whole-cell patch clamp recordings from substantia gelatinosa (SG) neurons of rat lumbar spinal cord slices revealed two distinct actions of exogenous Endo-1 and Endo-2: (1) depression of excitatory and/or inhibitory postsynaptic potentials evoked by stimulation of dorsal root entry zone, and (2) hyperpolarization of SG neurons. These two effects were prevented by the selective mu-opiate receptor antagonist beta-funaltrexamine. The localization of endomorphin-positive fibers in superficial layers of the dorsal horn and the release of irEndo upon stimulation of dorsal root afferents together with the observation that Endo inhibits the activity of SG neurons by interacting with mu-opiate receptors provide additional support of a role of Endo as the endogenous ligand for the mu-opiate receptor in the rat dorsal horn.

  9. Antinociception induced by intravenous dipyrone (metamizol) upon dorsal horn neurons: involvement of endogenous opioids at the periaqueductal gray matter, the nucleus raphe magnus, and the spinal cord in rats.

    PubMed

    Vazquez, Enrique; Hernandez, Norma; Escobar, William; Vanegas, Horacio

    2005-06-28

    Microinjection of dipyrone (metamizol) into the periaqueductal gray matter (PAG) in rats causes antinociception. This is mediated by endogenous opioidergic circuits located in the PAG itself, in the nucleus raphe magnus and adjacent structures, and in the spinal cord. The clinical relevance of these findings, however, is unclear. Therefore, in the present study, dipyrone was administered intravenously, and the involvement of endogenous opioidergic circuits in the so-induced antinociception was investigated. In rats, responses of dorsal spinal wide-dynamic range neurons to mechanical noxious stimulation of a hindpaw were strongly inhibited by intravenous dipyrone (200 mg/kg). This effect was abolished by microinjection of naloxone (0.5 microg/0.5 microl) into the ventrolateral and lateral PAG or into the nucleus raphe magnus or by direct application of naloxone (50 microg/50 microl) onto the spinal cord surface above the recorded neuron. These results show that dipyrone, a non-opioid analgesic with widespread use in Europe and Latin America, when administered in a clinically relevant fashion causes antinociception by activating endogenous opioidergic circuits along the descending pain control system.

  10. 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 Central

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

    2014-01-01

    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 two 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

  11. Neurokinin-1 (NK-1) receptor and brain-derived neurotrophic factor (BDNF) gene expression is differentially modulated in the rat spinal dorsal horn and hippocampus during inflammatory pain.

    PubMed

    Duric, Vanja; McCarson, Kenneth E

    2007-10-31

    Persistent pain produces complex alterations in sensory pathways of the central nervous system (CNS) through activation of various nociceptive mechanisms. However, the effects of pain on higher brain centers, particularly the influence of the stressful component of pain on the limbic system, are poorly understood. Neurokinin-1 (NK-1) receptors and brain-derived neurotrophic factor (BDNF), known neuromediators of hyperalgesia and spinal central sensitization, have also been implicated in the plasticity and neurodegeneration occurring in the hippocampal formation during exposures to various stressors. Results of this study showed that injections of complete Freund's adjuvant (CFA) into the hind paw increased NK-1 receptor and BDNF mRNA levels in the ipsilateral dorsal horn, supporting an important role for these nociceptive mediators in the amplification of ascending pain signaling. An opposite effect was observed in the hippocampus, where CFA down-regulated NK-1 receptor and BDNF gene expression, phenomena previously observed in immobilization models of stress and depression. Western blot analyses demonstrated that in the spinal cord, CFA also increased levels of phosphorylated cAMP response element-binding protein (CREB), while in the hippocampus the activation of this transcription factor was significantly reduced, further suggesting that tissue specific transcription of either NK-1 or BDNF genes may be partially regulated by common intracellular transduction mechanisms mediated through activation of CREB. These findings suggest that persistent nociception induces differential regional regulation of NK-1 receptor and BDNF gene expression and CREB activation in the CNS, potentially reflecting varied roles of these neuromodulators in the spinal cord during persistent sensory activation vs. modulation of the higher brain structures such as the hippocampus.

  12. “Three Methods and Three Points” regulates p38 mitogen-activated protein kinase in the dorsal horn of the spinal cord in a rat model of sciatic nerve injury

    PubMed Central

    Guo, Xin; Yu, Tian-yuan; Steven, Wong; Jia, Wen-duan; Ma, Chi; Tao, Yan-hong; Yang, Chao; Lv, Tao-tao; Wu, Shuai; Lu, Meng-qian; Liu, Jia-li

    2016-01-01

    Tuina is a traditional Chinese treatment for sensory disturbances caused by peripheral nerve injury and related diseases. Our previous studies showed that tuina regulates relevant regions and indices of the spinal dorsal horn using the Dian, Bo, and Rou method in Yinmen (BL37), Yanglingquan (GB34), and Weizhong (BL40). Treatment prevents muscle atrophy, protects spinal cord neurons, and promotes sciatic nerve repair. The mechanisms of action of tuina for treating peripheral nerve injury remain poorly understood. This study established rat models of sciatic nerve injury using the crushing method. Rats received Chinese tuina in accordance with the principle of “Three Methods and Three Points,” once daily for 20 days. Tuina intervention reduced paw withdrawal latency and improved wet weight of the gastrocnemius muscle, as well as promoting morphological recovery of sciatic nerve fibers, Schwann cells, and axons. The protein expression levels of phospho-p38 mitogen-activated protein kinase, tumor necrosis factor-α, and interleukin-1β also decreased. These findings indicate that “Three Methods and Three Points” promoted morphological recovery and improved behavior of rats with peripheral nerve injury. PMID:28197201

  13. Comparative immunohistochemical localisation of GABA(B1a), GABA(B1b) and GABA(B2) subunits in rat brain, spinal cord and dorsal root ganglion.

    PubMed

    Charles, K J; Evans, M L; Robbins, M J; Calver, A R; Leslie, R A; Pangalos, M N

    2001-01-01

    GABA(B) receptors are G-protein-coupled receptors mediating the slow onset and prolonged synaptic actions of GABA in the CNS. The recent cloning of two genes, GABA(B1) and GABA(B2), has revealed a novel requirement for GABA(B) receptor signalling. Studies have demonstrated that the two receptor subunits associate as a GABA(B1)/GABA(B2) heterodimer to form a functional GABA(B) receptor. In this study we have developed polyclonal antisera specific to two splice variants of the GABA(B1) subunit, GABA(B1a) and GABA(B1b), as well as an antiserum to the GABA(B2) subunit. Using affinity-purified antibodies derived from these antisera we have mapped out the distribution profile of each subunit in rat brain, spinal cord and dorsal root ganglion. In brain the highest areas of GABA(B1a), GABA(B1b) and GABA(B2) subunit expression were found in neocortex, hippocampus, thalamus, cerebellum and habenula. In spinal cord, GABA(B1) and GABA(B2) subunits were expressed in the superficial layers of the dorsal horn, as well as in motor neurones in the deeper layers of the ventral horn. GABA(B) receptor subunit immunoreactivity in dorsal root ganglion suggested that expression of GABA(B1b) was restricted to the large diameter neurones, in contrast to GABA(B1a) and GABA(B2) subunits which were expressed in both large and small diameter neurones. Although expression levels of GABA(B1) and GABA(B2) subunits varied we found no areas in which GABA(B1) was expressed in the absence of GABA(B2). This suggests that most, if not all, GABA(B1) immunoreactivity may represent functional GABA(B) receptors. Although our data are in general agreement with functional studies, some discrepancies in GABA(B1) subunit expression occurred with respect to other immunohistochemical studies. Overall our data suggest that GABA(B) receptors are widely expressed throughout the brain and spinal cord, and that GABA(B1a) and GABA(B1b) subunits can associate with GABA(B2) to form both pre- and post-synaptic receptors.

  14. Recombinant neural progenitor transplants in the spinal dorsal horn alleviate chronic central neuropathic pain.

    PubMed

    Jergova, Stanislava; Gajavelli, Shyam; Pathak, Nirmal; Sagen, Jacqueline

    2016-04-01

    Neuropathic pain induced by spinal cord injury (SCI) is clinically challenging with inadequate long-term treatment options. Partial pain relief offered by pharmacologic treatment is often counterbalanced by adverse effects after prolonged use in chronic pain patients. Cell-based therapy for neuropathic pain using GABAergic neuronal progenitor cells (NPCs) has the potential to overcome untoward effects of systemic pharmacotherapy while enhancing analgesic potency due to local activation of GABAergic signaling in the spinal cord. However, multifactorial anomalies underlying chronic pain will likely require simultaneous targeting of multiple mechanisms. Here, we explore the analgesic potential of genetically modified rat embryonic GABAergic NPCs releasing a peptidergic NMDA receptor antagonist, Serine-histogranin (SHG), thus targeting both spinal hyperexcitability and reduced inhibitory processes. Recombinant NPCs were designed using either lentiviral or adeno-associated viral vectors (AAV2/8) encoding single and multimeric (6 copies of SHG) cDNA. Intraspinal injection of recombinant cells elicited enhanced analgesic effects compared with nonrecombinant NPCs in SCI-induced pain in rats. Moreover, potent and sustained antinociception was achieved, even after a 5-week postinjury delay, using recombinant multimeric NPCs. Intrathecal injection of SHG antibody attenuated analgesic effects of the recombinant grafts suggesting active participation of SHG in these antinociceptive effects. Immunoblots and immunocytochemical assays indicated ongoing recombinant peptide production and secretion in the grafted host spinal cords. These results support the potential for engineered NPCs grafted into the spinal dorsal horn to alleviate chronic neuropathic pain.

  15. Resveratrol protects spinal cord dorsal column from hypoxic injury by activating Nrf-2.

    PubMed

    Kesherwani, V; Atif, F; Yousuf, S; Agrawal, S K

    2013-06-25

    Damage from oxidative stress plays a critical role in spinal cord injury. Nuclear factor erythroid 2-related factor (Nrf-2) signaling pathway can be activated by cellular oxidative stress. Resveratrol, a plant-derived polyphenolic compound found in red wine, has antioxidant properties. In the present study, we have examined the neuroprotective effect of resveratrol and the role of Nrf-2 in spinal cord hypoxic injury. The spinal cord was removed from adult male Wistar rats from T2-T10 and the dorsal column was used to induce hypoxic injury in vitro with and without treatment with resveratrol (50μM). Significant changes were found in the compound action potential (CAP) of spinal cord dorsal column, and hematoxyline and eosin (H&E) staining showed that resveratrol significantly improved neuronal injury. The biochemical assays showed significant changes in lipid peroxidase (LPO), reduced glutathione (GSH), superoxide dismutase (SOD), protein carbonyl (PC), mitochondrial ATP content, and mitochondrial Ca(++). Furthermore, using immunohistochemistry and Western blot, we found that after resveratrol treatment during hypoxic injury there was a significant activation of NrF-2 and down regulation of the glial fibrillary acidic protein (GFAP) content. The results show that resveratrol treatment has neuroprotective effects on CAP, Ca(++) loading, and biochemical parameters after hypoxic injury. The neuroprotective effect is likely to be exerted by increased activation of transcription factor Nrf-2 by resveratrol along with its direct antioxidant effect to ameliorate the oxidative damage and preserve mitochondrial function.

  16. 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.

  17. The contributions to the human dorsal column tracts from the spinal cord laminae.

    PubMed

    Kirazlı, Özlem; Solmaz, Bilgehan; Çavdar, Safiye

    2016-09-01

    The dorsal column tracts (fasciculus gracilis and fasciculus cuneatus) are concerned with discriminative qualities of sensation. There are controversial descriptions related to the relations of dorsal column tracts with the dorsal horn laminae in text-books. The present study aims to define the laminae of the dorsal horn of the spinal cord that contribute fibers to the dorsal column tracts in the cervical, thoracic and lumbar spinal level. Series paraffin spinal cords sections of six formalin-embalmed adult human cadavers were evaluated. The present study shows that dorsal column tracts receive fiber contributions from laminae III and V and from Clarke's dorsal nucleus at varying spinal levels. At upper cervical levels (C1-C4) fiber contributions were from lamina V and few from lamina III, and at lower cervical levels (C5-C8) there were, in addition to these laminae, also contributions from the Clarke's dorsal nucleus. At upper thoracic levels (T1-T4) fiber contributions were from lamina V and few from Clarke's dorsal nucleus. At lower thoracic (T5-T12) and lumbar levels (L1-L5), in contrast, fiber contributions were only from Clarke's dorsal nucleus. The detailed knowledge of organization of the dorsal column tracts of the spinal cord may pave the way for future treatments of the spinal cord injuries.

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

    PubMed

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

    2017-01-01

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

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

    PubMed Central

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

    2017-01-01

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

  20. 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

  1. 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.

  2. EZH2 regulates spinal neuroinflammation in rats with neuropathic pain.

    PubMed

    Yadav, Ruchi; Weng, Han-Rong

    2017-05-04

    Alteration in gene expression along the pain signaling pathway is a key mechanism contributing to the genesis of neuropathic pain. Accumulating studies have shown that epigenetic regulation plays a crucial role in nociceptive process in the spinal dorsal horn. In this present study, we investigated the role of enhancer of zeste homolog-2 (EZH2), a subunit of the polycomb repressive complex 2, in the spinal dorsal horn in the genesis of neuropathic pain in rats induced by partial sciatic nerve ligation. EZH2 is a histone methyltransferase, which catalyzes the methylation of histone H3 on K27 (H3K27), resulting in gene silencing. We found that levels of EZH2 and tri-methylated H3K27 (H3K27TM) in the spinal dorsal horn were increased in rats with neuropathic pain on day 3 and day 10 post nerve injuries. EZH2 was predominantly expressed in neurons in the spinal dorsal horn under normal conditions. The number of neurons with EZH2 expression was increased after nerve injury. More strikingly, nerve injury drastically increased the number of microglia with EZH2 expression by more than sevenfold. Intrathecal injection of the EZH2 inhibitor attenuated the development and maintenance of mechanical and thermal hyperalgesia in rats with nerve injury. Such analgesic effects were concurrently associated with the reduced levels of EZH2, H3K27TM, Iba1, GFAP, TNF-α, IL-1β, and MCP-1 in the spinal dorsal horn in rats with nerve injury. Our results highly suggest that targeting the EZH2 signaling pathway could be an effective approach for the management of neuropathic pain.

  3. Increased Presynaptic and Postsynaptic α2-Adrenoceptor Activity in the Spinal Dorsal Horn in Painful Diabetic Neuropathy

    PubMed Central

    Chen, Hong; Yuan, Wei-Xiu; Pan, Hui-Lin

    2011-01-01

    Diabetic neuropathy is a common cause of chronic pain that is not adequately relieved by conventional analgesics. The α2-adrenoceptors are involved in the regulation of glutamatergic input and nociceptive transmission in the spinal dorsal horn, but their functional changes in diabetic neuropathy are not clear. The purpose of the present study was to determine the plasticity of presynaptic and postsynaptic α2-adrenoceptors in the control of spinal glutamatergic synaptic transmission in painful diabetic neuropathy. Whole-cell voltage-clamp recordings of lamina II neurons were performed in spinal cord slices from streptozotocin-induced diabetic rats. The amplitude of glutamatergic excitatory postsynaptic currents (EPSCs) evoked from the dorsal root and the frequency of spontaneous EPSCs (sEPSCs) were significantly higher in diabetic than vehicle-control rats. The specific α2-adrenoceptor agonist 5-bromo-6-(2-imidazolin-2-ylamino)quinoxaline (UK-14304) (0.1–2 μM) inhibited the frequency of sEPSCs more in diabetic than vehicle-treated rats. UK-14304 also inhibited the amplitude of evoked monosynaptic and polysynaptic EPSCs more in diabetic than control rats. Furthermore, the amplitude of postsynaptic G protein-coupled inwardly rectifying K+ channel (GIRK) currents elicited by UK-14304 was significantly larger in the diabetic group than in the control group. In addition, intrathecal administration of UK-14304 increased the nociceptive threshold more in diabetic than vehicle-control rats. Our findings suggest that diabetic neuropathy increases the activity of presynaptic and postsynaptic α2-adrenoceptors to attenuate glutamatergic transmission in the spinal dorsal horn, which accounts for the potentiated antinociceptive effect of α2-adrenoceptor activation in diabetic neuropathic pain. PMID:21248068

  4. 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.

  5. Activation of neurotrophins in lumbar dorsal root probably contributes to neuropathic pain after spinal nerve ligation

    PubMed Central

    Kazemi, Abdolreza; Rahmati, Masoud; Eslami, Rasoul; Sheibani, Vahid

    2017-01-01

    Objective(s): Neurotrophins (NTs) exert various effects on neuronal system. Growing evidence indicates that NTs are involved in the pathophysiology of neuropathic pain. However, the exact role of these proteins in modulating nociceptive signaling requires being defined. Thus, the aim of this study was to evaluate the effects of spinal nerve ligation (SNL) on NTs activation in the lumbar dorsal root. Materials and Methods: Ten male Wistar rats were randomly assigned to two groups: tight ligation of the L5 spinal nerve (SNL: n=5) and Sham (n=5). In order to produce neuropathic pain, the L5 spinal nerve was tightly ligated (SNL). Then, allodynia and hyperalgesia tests were conducted weekly. After 4 weeks, tissue samples were taken from the two groups for laboratory evaluations. Here, Real-Time PCR quantity method was used for measuring NTs gene expression levels. Results: SNL resulted in a significant weight loss in the soleus muscle (P<0.05), mechanical allodynia and thermal hyperalgesia thresholds (respectively, P<0.05; P<0.05). Also, NGF, NT-4, NT-3, TrkA, TrkB and TrkC expression were up-regulated following spinal nerve ligation group (respectively, P=0.025, P=0.013, P=0.001, P=0.002, P<0.001, P=001) (respectively, 4.7, 5.2, 7.5, 5.1, 7.2, 6.2 folds). Conclusion: The present study provides new evidence that neuropathic pain induced by spinal nerve ligation probably activates NTs and Trk receptors expression in DRG. However, further studies are needed to better elucidate the role of NTs in a neuropathic pain. PMID:28133521

  6. The antiallodynic effect of intrathecal tianeptine is exerted by increased serotonin and norepinephrine in the spinal dorsal horn.

    PubMed

    Lee, Hyung Gon; Choi, Jeong Il; Yoon, Myung Ha; Obata, Hideaki; Saito, Shigeru; Kim, Woong Mo

    2014-11-07

    The purpose of this study was to validate the effects of tianeptine on serotonergic and noradrenergic neurotransmission in a rat model of neuropathic pain. Neuropathic pain was induced by ligating the L5 and L6 spinal nerves in male Sprague-Dawley rats, and mechanical allodynia was assessed using von Frey filaments. The effects of intrathecally administered tianeptine on mechanical allodynia were assessed. Dihydroergocristine or yohimbine, a serotonergic or α-2 adrenergic receptor antagonists, respectively, were intrathecally administered 10min before tianeptine to investigate its mechanism of action. Additionally microdialysis studies were performed to measure the extracellular levels of serotonin (5-HT) and norepinephrine (NE) in the spinal dorsal horn following tianeptine administration. Intrathecal tianeptine significantly increased the paw withdrawal thresholds in a dose-dependent manner and the antiallodynic effect was antagonized by dihydroergocristine and yohimbine. Microdialysis studies revealed that tianeptine increased the levels of 5-HT and NE in the spinal dorsal horn. These findings suggest that tianeptine may be effective for the management of neuropathic pain and that its analgesic mechanism is exerted by increased levels of 5-HT and NE in the synaptic cleft at the spinal level.

  7. Activity correlations between on-like and off-like cells of the rostral ventromedial medulla and simultaneously recorded wide-dynamic-range neurons of the spinal dorsal horn in rats.

    PubMed

    Salas, Rafael; Ramirez, Karla; Vanegas, Horacio; Vazquez, Enrique

    2016-12-01

    Considerable evidence supports the notion that on- and off-cells of the rostral ventromedial medulla (RVM) facilitate and depress, respectively, spinal nociceptive transmission. This notion stems from a covariation of on- or off-cell activities and spinal nocifensive reflexes. Such covariation could theoretically be due to their independently responding to a common source, or to an RVM-derived modulation of ventral horn neurons. Here, we tested whether on- and off-cells indeed modulate spinal nociceptive neurons. In deeply anesthetized rats, unitary recordings were simultaneously made from an RVM on-like or off-like cell and a spinal nociceptive neuron that shared a receptive field (RF) at a hind paw. Action potential firing in RVM/spinal neuron pairs was highly correlated, positively for on-like cells and negatively for off-like cells, both during ongoing activity and during application of calibrated noxious pressure to the RF. Microinjection of morphine into RVM induced a correlated decrease in on-like cell/spinal neuron ongoing activity and response to noxious stimulation. RVM morphine induced changes in off-like cell activity that were not correlated with spinal neuronal activity. These results suggest that on-cells exert a positive modulation upon spinal nociceptive neurons, upstream to ventral horn circuits and plausibly at the origin of nociceptive information that eventually reaches the cerebral cortex. On-cells may in this manner contribute to inflammation- and neuropathy-induced increases in withdrawal reflexes. Most significantly, on-cell modulation of nociceptive neurons may be a key factor in clinical pain conditions such as hyperalgesia and allodynia.

  8. De novo expression of Nav1.7 in injured putative proprioceptive afferents: Multiple tetrodotoxin-sensitive sodium channels are retained in the rat dorsal root after spinal nerve ligation.

    PubMed

    Fukuoka, T; Miyoshi, K; Noguchi, K

    2015-01-22

    Tetrodotoxin-sensitive (TTX-s) spontaneous activity is recorded from the dorsal roots after peripheral nerve injury. Primary sensory neurons in the dorsal root ganglion (DRG) express multiple TTX-s voltage-gated sodium channel α-subunits (Navs). Since Nav1.3 increases, whereas all other Navs decrease, in the DRG neurons after peripheral nerve lesion, Nav1.3 is proposed to be critical for the generation of these spontaneous discharges and the contributions of other Navs have been ignored. Here, we re-evaluate the changes in expression of three other TTX-s Navs, Nav1.1, Nav1.6 and Nav1.7, in the injured 5th lumbar (L5) primary afferent components following L5 spinal nerve ligation (SNL) using in situ hybridization histochemistry and immunohistochemistry. While the overall signal intensities for these Nav mRNAs decreased, many injured DRG neurons still expressed these transcripts at clearly detectable levels. All these Nav proteins accumulated at the proximal stump of the ligated L5 spinal nerve. The immunostaining patterns of Nav1.6 and Nav1.7 associated with the nodes of Ranvier were maintained in the ipsilateral L5 dorsal root. Interestingly, putative proprioceptive neurons characterized by α3 Na+/K+ ATPase-immunostaining specifically lacked Nav1.7 mRNA in naïve DRG but displayed de novo expression of this transcript following SNL. Nav1.7-immunoreactive fibers were significantly increased in the ipsilateral gracile nucleus where central axonal branches of the injured A-fiber afferents terminated. These data indicate that multiple TTX-s channel subunits could contribute to the generation and propagation of the spontaneous discharges in the injured primary afferents. Specifically, Nav1.7 may cause some functional changes in sensory processing in the gracile nucleus after peripheral nerve injury.

  9. Spinally projecting neurons of the dorsal column nucleus in a reptile: locus of origin and trajectory of termination.

    PubMed

    Pritz, M B

    1996-01-01

    Interconnections between the dorsal column nucleus and the spinal cord were investigated in a reptile, Caiman crocodilus. After placement of an anterograde tracer into the dorsal column nucleus, descending fibers are seen to leave this nucleus to enter the dorsal funiculus where they course ventrally to terminate in lamina V of the spinal cord as far caudally as C2. Placement of a retrograde tracer into cut fibers of the cervical spinal cord identified the relay cells of the dorsal column nucleus that project to the spinal cord. These neurons were mainly clustered in a caudal and ventral part of this nucleus. The soma of these spinally projecting cells were small and were generally round or oval in shape. A number of these neurons had the long axis of their soma oriented dorsoventrally, with a primary dendrite extending dorsally. Fibers in the dorsal funiculus that originated from the spinal cord enter the caudal part of the dorsal column nucleus and turn ventral. In the dorsal column nucleus, these axons run parallel to the vertically oriented dendrites of these spinally projecting cells before termination in close relation to the cell bodies of these neurons. Quantitative observations (mean +/- standard error) were made on well labeled neurons and included several measurements: area, perimeter, and degree of eccentricity (greatest width/greatest length) in both the transverse as well as the sagittal plane. These spinally projecting neurons in Caiman are located in the dorsal column nucleus in a position similar to that of spinally projecting cells in cats.

  10. A grasp-related deficit in tactile discrimination following dorsal column lesion in the rat.

    PubMed

    Ballermann, M; McKenna, J; Whishaw, I Q

    2001-01-15

    The dorsal columns of the spinal cord are a major source of haptic (sense of active touch) and proprioceptive input to the brainstem and sensory-motor cortex. Following injury in primates, there are impairments in two-point discrimination, direction of movement across the skin, and frequency of vibration, and qualitative control of the digits, but simple spatial discriminations recover. In the rat there are qualitative deficits in paw control in skilled reaching, but no sensory deficits have been reported. Because recent investigations of sensory control suggest that sensory functions may be related to specific actions, the present study investigated whether the dorsal columns contribute to hapsis during food grasping in the rat. Adult female Long-Evans rats were trained to reach with a single forepaw for a piece of uncooked pasta or for equivalent sized but tactually different nonfood items. One group was given lesions of the dorsal column ipsilateral to their preferred paw, while the second group served as a control. Postlesion, both groups were tested for skilled reaching success and force application as well as adhesive dot removal and forepaw placing. Performance levels on these tests were normal. Nevertheless, the rats with dorsal column lesions were unable to discriminate a food item from a tactually distinctive nonfood item as part of the reaching act, suggesting that the dorsal columns are important for on-line tactile discriminations, or "haptic actions," which contribute to the normal performance of grasping actions.

  11. Cervical dorsal rhizotomy increases brain-derived neurotrophic factor and neurotrophin-3 expression in the ventral spinal cord.

    PubMed

    Johnson, R A; Okragly, A J; Haak-Frendscho, M; Mitchell, G S

    2000-05-15

    Although neurotrophic factors have been implicated in several forms of neuroplasticity, little is known concerning their potential role in spinal plasticity. Cervical dorsal rhizotomy (CDR) enhances serotonin terminal density near (spinal) phrenic motoneurons and serotonin-dependent long-term facilitation of phrenic motor output (Kinkead et al., 1998). We tested the hypothesis that selected neurotrophic factors change in a manner consistent with an involvement in this model of spinal plasticity. Brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), glial cell line-derived neurotrophic factor (GDNF), and transforming growth factor-beta(1) (TGF-beta(1)) concentrations were measured (ELISA) in three regions of interest to respiratory control: (1) ventral cervical spinal segments associated with the phrenic motor nucleus (C3-C6), (2) ventral thoracic spinal segments associated with inspiratory intercostal motor output (T3-T6) and (3) the diaphragm. Tissues were harvested from rats 7 d after bilateral CDR and compared with sham-operated and unoperated control rats. CDR increased BDNF (110%; p = 0.002) and NT-3 (100%; p = 0.002) in the cervical and NT-3 in the thoracic spinal cord (98%; p = 0.009). GDNF and TGF-beta(1) were not altered by CDR in any tissue. Immunohistochemistry localized BDNF and NT-3 to motoneurons and interneurons of the ventral spinal cord. These studies provide novel, suggestive evidence that BDNF and NT-3, possibly through their trophic effects on serotonergic neurons and/or motoneurons, may underlie serotonin-dependent plasticity in (spinal) respiratory motor control after CDR.

  12. [Subpopulation of calbindin-immunoreactive interneurons in the dorsal horn of the mice spinal cord].

    PubMed

    Porseva, V V; Shilkin, V V; Strelkov, A A; Masliukov, P M

    2014-01-01

    In the dorsal horn of the spinal cord in the plates I-IV on the thoracic and lumbar levels different subpopulations of interneurons immunoreactive for calbindin 28 kDa (CAB IR), which are specific to each plate. In the area of the medial edge of the dorsal horn, we have found a special subpopulation of CAB IR interneurons whose morphometric characteristics differ from CAB IR interneurons subpopulations of said plates. The number of CAB IR interneurons was maximal in the plate II at all levels of the spinal cord. Leveled differences are more CAB IR interneurons and larger area of the cross sections at the lumbar level.

  13. Dopamine is produced in the rat spinal cord and regulates micturition reflex after spinal cord injury.

    PubMed

    Hou, Shaoping; Carson, David M; Wu, Di; Klaw, Michelle C; Houlé, John D; Tom, Veronica J

    2016-11-01

    Dopamine (DA) neurons in the mammalian central nervous system are thought to be restricted to the brain. DA-mediated regulation of urinary activity is considered to occur through an interaction between midbrain DA neurons and the pontine micturition center. Here we show that DA is produced in the rat spinal cord and modulates the bladder reflex. We observed numerous tyrosine hydroxylase (TH)(+) neurons in the autonomic nuclei and superficial dorsal horn in L6-S3 spinal segments. These neurons are dopamine-β-hydroxylase (DBH)(-) and some contain detectable dopamine decarboxylase (DDC), suggesting their capacity to produce DA. Interestingly, following a complete thoracic spinal cord injury (SCI) to interrupt supraspinal projections, more TH(+) neurons emerged in the lumbosacral spinal cord, coincident with a sustained, low level of DA expression there and a partially recovered micturition reflex. Non-selective blockade of spinal DA receptors reduced bladder activity whereas activation of spinal D2-like receptors increased bladder activity and facilitated voiding. Additionally, depletion of lumbosacral TH(+) neurons with 6-hydroxydopamine (6-OHDA) decreased bladder non-voiding contractions and voiding efficiency. Furthermore, injecting the transsynaptic neuronal tracer pseudorabies virus (PRV) into the bladder detrusor labeled TH(+) cells in the lumbosacral cord, confirming their involvement in spinal micturition reflex circuits. These results illustrate that DA is synthesized in the rat spinal cord; plasticity of lumbosacral TH(+) neurons following SCI may contribute to DA expression and modulate the spinal bladder reflex. Thus, spinally-derived DA and receptors could be a novel therapeutic target to improve micturition recovery after SCI.

  14. 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.

  15. Squamous cell carcinoma causing dorsal atlantoaxial spinal cord compression in a dog.

    PubMed

    Miyazaki, Yuta; Aikawa, Takeshi; Nishimura, Masaaki; Iwata, Munetaka; Kagawa, Yumiko

    2016-10-01

    A 12-year-old Chihuahua dog was presented for cervical pain and progressive tetraparesis. Magnetic resonance imaging revealed spinal cord compression due to a mass in the dorsal atlantoaxial region. Surgical treatment was performed. The mass was histopathologically diagnosed as a squamous cell carcinoma. The dog recovered to normal neurologic status after surgery.

  16. Localization of Brain Natriuretic Peptide Immunoreactivity in Rat Spinal Cord

    PubMed Central

    Abdelalim, Essam M.; Bellier, Jean-Pierre; Tooyama, Ikuo

    2016-01-01

    Brain natriuretic peptide (BNP) exerts its functions through NP receptors. Recently, BNP has been shown to be involved in a wide range of functions. Previous studies reported BNP expression in the sensory afferent fibers in the dorsal horn (DH) of the spinal cord. However, BNP expression and function in the neurons of the central nervous system are still controversial. Therefore, in this study, we investigated BNP expression in the rat spinal cord in detail using reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. RT-PCR analysis showed that BNP mRNA was present in the spinal cord and dorsal root ganglion (DRG). BNP immunoreactivity was observed in different structures of the spinal cord, including the neuronal cell bodies and neuronal processes. BNP immunoreactivity was observed in the DH of the spinal cord and in the neurons of the intermediate column (IC) and ventral horn (VH). Double-immunolabeling showed a high level of BNP expression in the afferent fibers (laminae I–II) labeled with calcitonin gene-related peptide (CGRP), suggesting BNP involvement in sensory function. In addition, BNP was co-localized with CGRP and choline acetyltransferase (ChAT) in the motor neurons of the VH. Together, these results indicate that BNP is expressed in sensory and motor systems of the spinal cord, suggesting its involvement in several biological actions on sensory and motor neurons via its binding to NP receptor-A (NPR-A) and/or NP receptor-B (NPR-B) at the spinal cord level. PMID:27994541

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. Upregulation of acid-sensing ion channel ASIC1a in spinal dorsal horn neurons contributes to inflammatory pain hypersensitivity.

    PubMed

    Duan, Bo; Wu, Long-Jun; Yu, Yao-Qing; Ding, Yu; Jing, Liang; Xu, Lin; Chen, Jun; Xu, Tian-Le

    2007-10-10

    Development of chronic pain involves alterations in peripheral nociceptors as well as elevated neuronal activity in multiple regions of the CNS. Previous pharmacological and behavioral studies suggest that peripheral acid-sensing ion channels (ASICs) contribute to pain sensation, and the expression of ASIC subunits is elevated in the rat spinal dorsal horn (SDH) in an inflammatory pain model. However, the cellular distribution and the functional consequence of increased ASIC subunit expression in the SDH remain unclear. Here, we identify the Ca2+-permeable, homomeric ASIC1a channels as the predominant ASICs in rat SDH neurons and downregulation of ASIC1a by local rat spinal infusion with specific inhibitors or antisense oligonucleotides markedly attenuated complete Freund's adjuvant (CFA)-induced thermal and mechanical hypersensitivity. Moreover, in vivo electrophysiological recording showed that the elevated ASIC1a activity is required for two forms of central sensitization: C-fiber-induced "wind-up" and CFA-induced hypersensitivity of SDH nociceptive neurons. Together, our results reveal that increased ASIC activity in SDH neurons promotes pain by central sensitization. Specific blockade of Ca2+-permeable ASIC1a channels thus may have antinociceptive effect by reducing or preventing the development of central sensitization induced by inflammation.

  2. Identifying functional populations among the interneurons in laminae I-III of the spinal dorsal horn

    PubMed Central

    2017-01-01

    The spinal dorsal horn receives input from primary afferent axons, which terminate in a modality-specific fashion in different laminae. The incoming somatosensory information is processed through complex synaptic circuits involving excitatory and inhibitory interneurons, before being transmitted to the brain via projection neurons for conscious perception. The dorsal horn is important, firstly because changes in this region contribute to chronic pain states, and secondly because it contains potential targets for the development of new treatments for pain. However, at present, we have only a limited understanding of the neuronal circuitry within this region, and this is largely because of the difficulty in defining functional populations among the excitatory and inhibitory interneurons. The recent discovery of specific neurochemically defined interneuron populations, together with the development of molecular genetic techniques for altering neuronal function in vivo, are resulting in a dramatic improvement in our understanding of somatosensory processing at the spinal level. PMID:28326935

  3. Calcium currents and GABAB receptors in the dorsal sensory cells of the lamprey spinal cord.

    PubMed

    Batueva, I V; Buchanan, J T; Tsvetkov, E A; Sagatelyan, A K; Veselkin, N P

    1999-01-01

    Patch-clamp studies were performed on the isolated dorsal sensory cells of the spinal cords of three species of lamprey, Ichthyomyzon unicuspis, Petromyzon marinus, and Lampetra fluviatilis, to measure changes in the amplitudes of calcium current induced by GABA and its specific antagonists and agonists. The experiments showed that GABA (4 mM) reduced the peak amplitude of the calcium current by 28.5 +/- 4.9%, with subsequent recovery to 96.2 +/- 9.2% of control (n = 45). The GABAB agonist baclofen had similar effects. The GABAA agonists glycine and taurine had no effect on the Ca2+ current. The inhibitory effect of GABA was blocked by 2-hydroxysaclofen (a GABAB antagonist), but persisted in the presence of bicuculline (a GABAA antagonist). These results are evidence that the membranes of dorsal sensory cells contain GABAB receptors, which significantly increases our understanding of the mechanisms of presynaptic inhibition in the spinal cords of the cyclostomata.

  4. Application of nucleus pulposus to L5 dorsal root ganglion in rats enhances nociceptive dorsal horn neuronal windup.

    PubMed

    Cuellar, J M; Montesano, P X; Antognini, J F; Carstens, E

    2005-07-01

    Herniation of the nucleus pulposus (NP) from lumbar intervertebral discs commonly results in radiculopathic pain possibly through a neuroinflammatory response. NP sensitizes dorsal horn neuronal responses, but it is unknown whether this reflects a central or peripheral sensitization. To study central sensitization, we tested if NP enhances windup--the progressive increase in the response of a nociceptive spinal neuron to repeated electrical C-fiber stimulation--a phenomenon that may partly account for temporal summation of pain. Single-unit recordings were made from wide dynamic range (WDR; n = 36) or nociceptive-specific (NS; n = 8) L5 dorsal horn neurons in 44 isoflurane-anesthetized rats. Subcutaneous electrodes delivered electrical stimuli (20 pulses, 3 times the C-fiber threshold, 0.5 ms) to the receptive field on the hindpaw. Autologous NP was harvested from a tail disc and placed onto the L5 dorsal root ganglion after recording of baseline responses (n = 22). Controls had saline applied similarly (n = 22). Electrical stimulus trains (0.1, 0.3, and 1 Hz; 5-min interstimulus interval) were repeated every 30 min for 3-6 h after each treatment. The total number of evoked spikes (summed across all 20 stimuli) to 0.1 Hz was enhanced 3 h after NP, mainly in the after-discharge (AD) period (latency > 400 ms). Total responses to 0.3 and 1.0 Hz were also enhanced at > or = 60 min after NP in both the C-fiber (100- to 400-ms latency) and AD periods, whereas the absolute windup (C-fiber + AD - 20 times the initial response) increased at > or = 90 min after treatment. In saline controls, windup was not enhanced at any time after treatment for any stimulus frequency, although there was a trend toward enhancement at 0.3 Hz. These results are consistent with NP-induced central sensitization. Mechanical responses were not significantly enhanced after saline or NP treatment. We speculate that inflammatory agents released from (or recruited by) NP affect the dorsal root

  5. Role of dorsal rhizotomy in spinal cord injury-induced spasticity.

    PubMed

    Reynolds, Renee M; Morton, Ryan P; Walker, Marion L; Massagli, Teresa L; Browd, Samuel R

    2014-09-01

    Selective dorsal rhizotomy may have a role in the management of spinal cord injury (SCI)-induced spasticity. Spasticity and spasms are common sequelae of SCI in children. Depending on the clinical scenario, treatments may include physical and occupational therapy, oral medications, chemodenervation, and neurosurgical interventions. Selective dorsal rhizotomy (SDR) is used in the management of spasticity in selected children with cerebral palsy, but, to the authors' knowledge, its use has not been reported in children with SCI. The authors describe the cases of 3 pediatric patients with SCI and associated spasticity treated with SDR. Two of the 3 patients have had significant long-term improvement in their preoperative spasticity. Although the third patient also experienced initial relief, his spasticity quickly returned to its preoperative severity, necessitating additional therapies. Selective dorsal rhizotomy may have a place in the treatment of selected children with spasticity due to SCI.

  6. Blocking PAR2 attenuates oxaliplatin-induced neuropathic pain via TRPV1 and releases of substance P and CGRP in superficial dorsal horn of spinal cord.

    PubMed

    Chen, Kun; Zhang, Zhi-Fa; Liao, Ming-Feng; Yao, Wen-Long; Wang, Juan; Wang, Xue-Ren

    2015-05-15

    Oxaliplatin (OXL) is a third-generation chemotherapeutic agent commonly used to treat metastatic digestive tumors; however, neuropathic pain is one of the main limiting complications of OXL. The purpose of this study was to examine the underlying mechanisms by which neuropathic pain is induced by OXL in a rat model. Our results demonstrated that blocking spinal proteinase-activated receptor 2 (PAR2) and transient receptor potential vanilloid 1 (TRPV1) attenuated pain responses evoked by mechanical stimulation and decreased the releases of substance P and CGRP in the superficial dorsal horn of the spinal cord. The attenuating effect on mechanical pain was significantly smaller in OXL-rats than that in control rats. Blocking PAR2 also attenuated a heightened cold sensitivity evoked by OXL; whereas blocking TRPV1 had little effects on OXL-evoked hypersensitive cold response. Our data also showed that OXL increased the protein expressions of PAR2 and TRPV1 in the superficial dorsal horn. In addition, blocking PAR2 decreased TRPV1 expression in OXL-rats. Overall, our data suggest that upregulated expression of PAR2 in the superficial dorsal horn contributes to mechanical hyperalgesia and cold hypersensitivity; whereas amplified TRPV1 plays a role in regulating mechanical hyperalgesia, but not cold hypersensitivity after administration of OXL. We further suggest that TRPV1 is likely one of the signaling pathways for PAR2 to play a role in regulating OXL-induced neuropathic pain.

  7. Single-unit analysis of the spinal dorsal horn in patients with neuropathic pain.

    PubMed

    Guenot, Marc; Bullier, Jean; Rospars, Jean-Pierre; Lansky, Petr; Mertens, Patrick; Sindou, Marc

    2003-04-01

    Despite the key role played by the dorsal horn of the spinal cord in pain modulation, single-unit recordings have only been performed very rarely in this structure in humans. The authors report the results of a statistical analysis of 64 unit recordings from the human dorsal horn. The recordings were done in three groups of patients: patients with deafferentation pain resulting from brachial plexus avulsion, patients with neuropathic pain resulting from peripheral nerve injury, and patients with pain resulting from disabling spasticity. The patterns of neuronal activities were compared among these three groups. Nineteen neurons were recorded in the dorsal horns of five patients undergoing DREZotomy for a persistent pain syndrome resulting from peripheral nerve injury (i.e., nondeafferented dorsal horns), 31 dorsal horn neurons were recorded in nine patients undergoing DREZotomy for a persistent pain syndrome resulting from brachial plexus avulsion (i.e., deafferented dorsal horns), and 14 neurons were recorded in eight patients undergoing DREZotomy for disabling spasticity. These groups were compared in terms of mean frequency, coefficient of variation of the discharge, other properties of the neuronal discharge studied by the nonparametric test of Wald-Wolfowitz, and the possible presence of bursts. The coefficient of variation tended to be higher in the deafferented dorsal horn group than in the other two groups. Two neurons displaying burst activity could be recorded, both of which belonged to the deafferented dorsal horn group. A significant difference was found in term of neuronal behavior between the peripheral nerve trauma group and the other groups: The brachial plexus avulsion and disabling spasticity groups were very similar, including various types of neuronal behavior, whereas the peripheral nerve lesion group included mostly neurons with "nonrandom" patterns of discharge (i.e., with serial dependency of interspike intervals).

  8. [Endovascular treatment of spinal dorsal intradural arteriovenous fistulas].

    PubMed

    Santos-Franco, Jorge Arturo; Collado-Arce, María Griselda Lizbeth; Dávila-Romero, Julio César; Saavedra-Andrade, Rafael; Sandoval-Balanzario, Miguel Antonio

    2015-01-01

    Introducción: las fístulas arteriovenosas intradurales dorsales espinales (FAVIDE) son lesiones poco frecuentes y complejas que son subdiagnósticadas y condicionan discapacidad. El objetivo es presentar nuestra experiencia en el manejo endovascular. Métodos: estudio ambispectivo de pacientes con FAVIDE, tratados mediante terapia endovascular (TEV) con n-butil-cianoacrilato en el periodo de 2007 a 2013. Resultados: se incluyeron 15 pacientes con edad media de 37 años. En 12 casos la presentación fue progresiva e insidiosa en un lapso de entre 6 meses y un año, mientras que 3 presentaron hemorragia. La lesión tuvo localización torácica en 73 % de los casos, lumbar en 20 % y cervical en 7 %. Previo al tratamiento observamos discapacidad de grados 5 y 4 en 73 %, y 67 % tenían alteraciones de la micción de grado 3. Como complicaciones, solo una paciente tuvo deterioro del estado de alerta transitorio 6 horas después del procedimiento. Se encontró una mejoría hacia los grados 1 y 2 de discapacidad, a las 48 horas, 3 y 6 meses, de 53 %, 73 % y 87 %, respectivamente. Conclusiones: con la TEV se tiene un tiempo quirúrgico corto, el volumen de hemorragia es bajo y la estancia hospitalaria es corta, respecto de otras técnicas quirúrgicas. La TEV es un procedimiento seguro y con efectividad significativa en el tratamiento de FAVIDE. Esta es la primera serie de casos tratados con TEV en México.

  9. Arrested development of the dorsal column following neonatal spinal cord injury in the opossum, Monodelphis domestica.

    PubMed

    Wheaton, Benjamin J; Noor, Natassya M; Dziegielewska, Katarzyna M; Whish, Sophie; Saunders, Norman R

    2015-03-01

    Developmental studies of spinal cord injury in which regrowth of axons occurs across the site of transection rarely distinguish between the recovery of motor-controlling pathways and that of ascending axons carrying sensory information. We describe the morphological changes that occur in the dorsal column (DC) of the grey short-tailed opossum, Monodelphis domestica, following spinal cord injury at two early developmental ages. The spinal cords of opossums that had had their mid-thoracic spinal cords completely transected at postnatal day 7 (P7) or P28 were analysed. Profiles of neurofilament immunoreactivity in transected cords showing DC development were differentially affected by the injury compared with the rest of the cord and cytoarchitecture was modified in an age- and site-dependent manner. The ability of DC neurites to grow across the site of transection was confirmed by injection of fluorescent tracer below the injury. P7 transected cords showed labelling in the DC above the site of original transection indicating that neurites of this sensory tract were able to span the injury. No growth of any neuronal processes was seen after P28 transection. Thus, DC is affected by spinal injury in a differential manner depending on the age at which the transection occurs. This age-differential response, together with other facets of remodelling that occur after neonatal spinal injury, might explain the locomotor adaptations and recovery observed in these animals.

  10. Regulation of neuropilin 1 by spinal cord injury in adult rats.

    PubMed

    Agudo, Marta; Robinson, Michelle; Cafferty, William; Bradbury, Elizabeth J; Kilkenny, Carol; Hunt, Stephen P; McMahon, Stephen B

    2005-03-01

    Using RT-PCR, in situ hybridization, Western blotting, and immunofluorescence, we have analyzed the expression of neuropilin 1 (Np1) in two models of spinal cord injury (spinal cord hemisection and dorsal column crush) and following dorsal root rhizotomy in adult rats. Our results show that Np1 RNA and protein are up-regulated in the spinal cord after all these lesions but remain unaltered in the adjacent dorsal root ganglia. In control animals, Np1 levels in the spinal cord are low and appear to be localized mainly in blood vessels, motoneurons, and in the superficial layers of the dorsal horn. After DCC and rhizotomy, Np1 is expressed de novo around the injury and in the deafferentated dorsal horn, respectively, mainly by OX42-positive microglial cells. Both lesions affect the sensory projections, and interestingly a consistent increase of Np1 signal is additionally seen in the dorsal horn where these projections terminate. Unexpectedly, this increase is bilateral after unilateral rhizotomy.

  11. 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.

  12. Modulation of activity and conduction in single dorsal column axons by kilohertz-frequency spinal cord stimulation.

    PubMed

    Crosby, Nathan D; Janik, John J; Grill, Warren M

    2017-01-01

    Kilohertz-frequency spinal cord stimulation (KHF-SCS) is a potential paresthesia-free treatment for chronic pain. However, the effects of KHF-SCS on spinal dorsal column (DC) axons and its mechanisms of action remain unknown. The objectives of this study were to quantify activation and conduction block of DC axons by KHF-SCS across a range of frequencies (1, 5, 10, or 20 kHz) and waveforms (biphasic pulses or sinusoids). Custom platinum electrodes delivered SCS to the T10/T11 dorsal columns of anesthetized male Sprague-Dawley rats. Single DC axons and compound action potentials were recorded during KHF-SCS to evaluate SCS-evoked activity. Responses to KHF-SCS in DC axons included brief onset firing, slowly accommodating asynchronous firing, and conduction block. The effects of KHF-SCS mostly occurred well above motor thresholds, but isolated units were activated at amplitudes shown to reduce behavioral sensitivity in rats. Activity evoked by SCS was similar across a range of frequencies (5-20 kHz) and waveforms (biphasic and sinusoidal). Stimulation at 1-kHz SCS evoked more axonal firing that was also more phase-synchronized to the SCS waveform, but only at amplitudes above motor threshold. These data quantitatively characterize the central nervous system activity that may modulate pain perception and paresthesia, and thereby provide a foundation for continued investigation of the mechanisms of KHF-SCS and its optimization as a therapy for chronic pain. Given the asynchronous and transient nature of DC activity, it is unlikely that the same mechanisms underlying conventional SCS (i.e., persistent, periodic DC activation) apply to KHF-SCS.

  13. Effect of reversible dorsal cold block on the persistence of inhibition generated by spinal reflexes.

    PubMed

    Miller, J F; Paul, K D; Jiang, B; Rymer, W Z; Heckman, C J

    1995-01-01

    The effects of bilateral focal cooling of dorsolateral thoracic spinal cord on segmental reflex pathways to the triceps surae muscles were assessed in decerebrate cats from the reflex forces produced by single shocks or trains of electrical stimuli applied to the ipsilateral caudal cutaneous sural and the contralateral tibial nerves. The validity of the dorsal cold block technique as a substitute for acute surgical dorsal hemisection was established by showing that focal cooling reliably reproduced the stretch-induced "clasp knife" inhibition of triceps surae reflexive force seen following dorsal hemisection. Under control (warm) conditions, the inhibitory components of electrically evoked ipsilateral sural and contralateral tibial reflexes faded rapidly during sustained trains, with a resultant production of large-amplitude reflex force as measured from either the entire triceps surae or from the medial gastrocnemius muscle alone. Dorsal cold block greatly reduced the amplitude of reflexive force evoked by sustained electrical stimulation of either nerve. Indeed, the cold block completely reversed the sign of train-evoked reflexes to a net inhibition of reflex force output in one-half of the sural and one-half of the contralateral tibial stimulation experiments. Peak transient forces evoked by single shocks to the sural or contralateral tibial nerves were also sometimes reduced, but this result was more variable than for prolonged nerve stimulation. The persistence of activity in segmental inhibitory pathways during dorsal cold block, as indicated by instances of reflex sign reversal, suggests that descending bulbospinal pathways traversing the dorsolateral funiculi may be responsible for "fading" of segmental inhibitory reflex components in decerebrate cats with intact spinal cords during sustained afferent input. The possibility that the enhanced magnitude and duration of segmental inhibition during cold block will increase the likelihood of disruption of the

  14. Spinal Autofluorescent Flavoprotein Imaging in a Rat Model of Nerve Injury-Induced Pain and the Effect of Spinal Cord Stimulation

    PubMed Central

    Jongen, Joost L. M.; Smits, Helwin; Pederzani, Tiziana; Bechakra, Malik; Hossaini, Mehdi; Koekkoek, Sebastiaan K.; Huygen, Frank J. P. M.; De Zeeuw, Chris I.; Holstege, Jan C.; Joosten, Elbert A. J.

    2014-01-01

    Nerve injury may cause neuropathic pain, which involves hyperexcitability of spinal dorsal horn neurons. The mechanisms of action of spinal cord stimulation (SCS), an established treatment for intractable neuropathic pain, are only partially understood. We used Autofluorescent Flavoprotein Imaging (AFI) to study changes in spinal dorsal horn metabolic activity. In the Seltzer model of nerve-injury induced pain, hypersensitivity was confirmed using the von Frey and hotplate test. 14 Days after nerve-injury, rats were anesthetized, a bipolar electrode was placed around the affected sciatic nerve and the spinal cord was exposed by a laminectomy at T13. AFI recordings were obtained in neuropathic rats and a control group of naïve rats following 10 seconds of electrical stimulation of the sciatic nerve at C-fiber strength, or following non-noxious palpation. Neuropathic rats were then treated with 30 minutes of SCS or sham stimulation and AFI recordings were obtained for up to 60 minutes after cessation of SCS/sham. Although AFI responses to noxious electrical stimulation were similar in neuropathic and naïve rats, only neuropathic rats demonstrated an AFI-response to palpation. Secondly, an immediate, short-lasting, but strong reduction in AFI intensity and area of excitation occurred following SCS, but not following sham stimulation. Our data confirm that AFI can be used to directly visualize changes in spinal metabolic activity following nerve injury and they imply that SCS acts through rapid modulation of nociceptive processing at the spinal level. PMID:25279562

  15. AP-2α and AP-2β regulate dorsal interneuron specification in the spinal cord.

    PubMed

    Xu, Xiaofeng; Liu, Zijing; Huang, Hao; Zheng, Kang; Hu, Xuemei; Zhang, Zunyi; Qiu, Mengsheng

    2017-01-06

    To date, five AP-2 genes that encode AP-2α, β, γ, δ and ε have been identified in vertebrates and they have been reported to be key regulators of embryonic development. However, the role of AP-2 family members in the development of central nervous system (CNS) has not been characterized. In the present study, we systematically examined the spatiotemporal expression pattern of AP-2 genes in the developing spinal cord of mouse and chick embryos and found that AP-2α and AP-2β are specifically expressed in post-mitotic dorsal interneurons. Loss-of-function analysis using in ovo electroporation in embryonic chick spinal cord preliminarily demonstrated that cAP-2α and cAP-2β regulates dorsal Class A and Class B interneuron specification, respectively. Gain-of-function experiments further revealed that misexpression of cAP-2α, but not cAP-2β, was able to induce the ectopic generation of Class A interneurons. Together, our studies indicated that AP-2 family members, AP-2α and AP-2β, have distinct functions in the regulation of dorsal interneuron development.

  16. Antidromic discharges of dorsal root afferents and inhibition of the lumbar monosynaptic reflex in the neonatal rat.

    PubMed

    Vinay, L; Clarac, F

    1999-04-01

    The in vitro brain stem-spinal cord preparation of neonatal (0- to five-day-old) rats was used to establish whether pathways descending from the brain stem are capable of modulating synaptic transmission from primary afferents to lumbar motoneurons within the first few days after birth. We stimulated the ventral funiculus of the spinal cord at the cervical (C1-C2) level. Single-pulse stimulations evoked both excitatory and inhibitory postsynaptic potentials in ipsilateral lumbar (L2-L5) motoneurons which were recorded intracellularly. Twin-pulse stimulations evoked bursts of action potentials in ventral roots. The amplitude of the monosynaptic dorsal root-evoked excitatory postsynaptic potential decreased when a conditioning stimulation was applied to the ventral funiculus 50-300 ms prior to the stimulation of the ipsilateral dorsal root. A decreased input resistance of the motoneurons during the early part (25-100 ms after the artifact) of the ventral funiculus-evoked postsynaptic potentials could account, at least partly, for the decreased amplitude of the dorsal root-evoked response. However, the duration of the inhibition of the dorsal root-evoked excitatory postsynaptic potential was longer than that of the decrease in input resistance. Ventral funiculus stimulation evoked antidromic discharges in dorsal roots. Recordings of dorsal root potentials showed that these discharges were generated by the underlying afferent terminal depolarizations reaching firing threshold. The dorsal root discharge overlapped with most of the time-course of the ventral funiculus-evoked inhibition of the response to dorsal root stimulation, suggesting that part of this inhibition may be exerted at a presynaptic level. The number of antidromic action potentials evoked in dorsal roots by ventral funiculus stimulation increased significantly in saline solution with chloride concentration reduced to 50% of control. Bursts of action potentials disappeared when chloride was removed

  17. Differentiation of idiopathic spinal cord herniation from dorsal arachnoid webs on MRI and CT myelography.

    PubMed

    Schultz, Randall; Steven, Andrew; Wessell, Aaron; Fischbein, Nancy; Sansur, Charles A; Gandhi, Dheeraj; Ibrahimi, David; Raghavan, Prashant

    2017-03-24

    OBJECTIVE Dorsal arachnoid webs (DAWs) and spinal cord herniation (SCH) are uncommon abnormalities affecting the thoracic spinal cord that can result in syringomyelia and significant neurological morbidity if left untreated. Differentiating these 2 entities on the basis of clinical presentation and radiological findings remains challenging but is of vital importance in planning a surgical approach. The authors examined the differences between DAWs and idiopathic SCH on MRI and CT myelography to improve diagnostic confidence prior to surgery. METHODS Review of the picture archiving and communication system (PACS) database between 2005 and 2015 identified 6 patients with DAW and 5 with SCH. Clinical data including demographic information, presenting symptoms and neurological signs, and surgical reports were collected from the electronic medical records. Ten of the 11 patients underwent MRI. CT myelography was performed in 3 patients with DAW and in 1 patient with SCH. Imaging studies were analyzed by 2 board-certified neuroradiologists for the following features: 1) location of the deformity; 2) presence or absence of cord signal abnormality or syringomyelia; 3) visible arachnoid web; 4) presence of a dural defect; 5) nature of dorsal cord indentation (abrupt "scalpel sign" vs "C"-shaped); 6) focal ventral cord kink; 7) presence of the nuclear trail sign (endplate irregularity, sclerosis, and/or disc-space calcification that could suggest a migratory path of a herniated disc); and 8) visualization of a complete plane of CSF ventral to the deformity. RESULTS The scalpel sign was positive in all patients with DAW. The dorsal indentation was C-shaped in 5 of 6 patients with SCH. The ventral subarachnoid space was preserved in all patients with DAW and interrupted in cases of SCH. In no patient was a web or a dural defect identified. CONCLUSIONS DAW and SCH can be reliably distinguished on imaging by scrutinizing the nature of the dorsal indentation and the integrity of

  18. Neuronal networks and nociceptive processing in the dorsal horn of the spinal cord.

    PubMed

    Cordero-Erausquin, Matilde; Inquimbert, Perrine; Schlichter, Rémy; Hugel, Sylvain

    2016-12-03

    The dorsal horn (DH) of the spinal cord receives a variety of sensory information arising from the inner and outer environment, as well as modulatory inputs from supraspinal centers. This information is integrated by the DH before being forwarded to brain areas where it may lead to pain perception. Spinal integration of this information relies on the interplay between different DH neurons forming complex and plastic neuronal networks. Elements of these networks are therefore potential targets for new analgesics and pain-relieving strategies. The present review aims at providing an overview of the current knowledge on these networks, with a special emphasis on those involving interlaminar communication in both physiological and pathological conditions.

  19. Spinal cord neuron inputs to the cuneate nucleus that partially survive dorsal column lesions: a pathway that could contribute to recovery after spinal cord injury

    PubMed Central

    Liao, Chia-Chi; DiCarlo, Gabriella E.; Gharbawie, Omar A.; Qi, Hui-Xin; Kaas, Jon H.

    2015-01-01

    Dorsal column lesions at a high cervical level deprive the cuneate nucleus and much of the somatosensory system of its major cutaneous inputs. Over weeks of recovery, much of the hand representations in the contralateral cortex are reactivated. One possibility for such cortical reactivation by hand afferents is that preserved second-order spinal cord neurons reach the cuneate nucleus through pathways that circumvent the dorsal column lesions, contributing to cortical reactivation in an increasingly effective manner over time. To evaluate this possibility, we first injected anatomical tracers into the cuneate nucleus and plotted the distributions of labeled spinal cord neurons and fibers in control monkeys. Large numbers of neurons in the dorsal horn of the cervical spinal cord were labeled, especially unilaterally in lamina IV. Labeled fibers were distributed in the cuneate fasciculus and lateral funiculus. In three other squirrel monkeys, unilateral dorsal column lesions were placed at the cervical segment 4 (C4) level and tracers were injected into the ipsilateral cuneate nucleus. Two weeks later, a largely unresponsive hand representation in contralateral somatosensory cortex confirmed the effectiveness of the dorsal column lesion. However, tracer injections in the cuneate nucleus labeled only about 5% of the normal number of dorsal horn neurons, mainly in lamina IV, below the level of lesions. Our results revealed a small second-order pathway to the cuneate nucleus that survives high cervical dorsal column lesions by traveling in the lateral funiculus. This could be important for cortical reactivation by hand afferents, and recovery of hand use. PMID:25845707

  20. Spinal cord neuron inputs to the cuneate nucleus that partially survive dorsal column lesions: A pathway that could contribute to recovery after spinal cord injury.

    PubMed

    Liao, Chia-Chi; DiCarlo, Gabriella E; Gharbawie, Omar A; Qi, Hui-Xin; Kaas, Jon H

    2015-10-01

    Dorsal column lesions at a high cervical level deprive the cuneate nucleus and much of the somatosensory system of its major cutaneous inputs. Over weeks of recovery, much of the hand representations in the contralateral cortex are reactivated. One possibility for such cortical reactivation by hand afferents is that preserved second-order spinal cord neurons reach the cuneate nucleus through pathways that circumvent the dorsal column lesions, contributing to cortical reactivation in an increasingly effective manner over time. To evaluate this possibility, we first injected anatomical tracers into the cuneate nucleus and plotted the distributions of labeled spinal cord neurons and fibers in control monkeys. Large numbers of neurons in the dorsal horn of the cervical spinal cord were labeled, especially ipsilaterally in lamina IV. Labeled fibers were distributed in the cuneate fasciculus and lateral funiculus. In three other squirrel monkeys, unilateral dorsal column lesions were placed at the cervical segment 4 level and tracers were injected into the ipsilateral cuneate nucleus. Two weeks later, a largely unresponsive hand representation in contralateral somatosensory cortex confirmed the effectiveness of the dorsal column lesion. However, tracer injections in the cuneate nucleus labeled only about 5% of the normal number of dorsal horn neurons, mainly in lamina IV, below the level of lesions. Our results revealed a small second-order pathway to the cuneate nucleus that survives high cervical dorsal column lesions by traveling in the lateral funiculus. This could be important for cortical reactivation by hand afferents, and recovery of hand use.

  1. 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

  2. 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

  3. Enhanced functional recovery in MRL/MpJ mice after spinal cord dorsal hemisection.

    PubMed

    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.

  4. 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.

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

    PubMed Central

    Tadros, M. A.; Lim, R.; Hughes, D. I.; Brichta, A. M.

    2015-01-01

    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. 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

  7. 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

  8. Glycinergic dysfunction in a subpopulation of dorsal horn interneurons in a rat model of neuropathic pain

    PubMed Central

    Imlach, Wendy L.; Bhola, Rebecca F.; Mohammadi, Sarasa A.; Christie, Macdonald J.

    2016-01-01

    The development of neuropathic pain involves persistent changes in signalling within pain pathways. Reduced inhibitory signalling in the spinal cord following nerve-injury has been used to explain sensory signs of neuropathic pain but specific circuits that lose inhibitory input have not been identified. This study shows a specific population of spinal cord interneurons, radial neurons, lose glycinergic inhibitory input in a rat partial sciatic nerve ligation (PNL) model of neuropathic pain. Radial neurons are excitatory neurons located in lamina II of the dorsal horn, and are readily identified by their morphology. The amplitude of electrically-evoked glycinergic inhibitory post-synaptic currents (eIPSCs) was greatly reduced in radial neurons following nerve-injury associated with increased paired-pulse ratio. There was also a reduction in frequency of spontaneous IPSCs (sIPSCs) and miniature IPSCs (mIPSC) in radial neurons without significantly affecting mIPSC amplitude. A subtype selective receptor antagonist and western blots established reversion to expression of the immature glycine receptor subunit GlyRα2 in radial neurons after PNL, consistent with slowed decay times of IPSCs. This study has important implications as it identifies a glycinergic synaptic connection in a specific population of dorsal horn neurons where loss of inhibitory signalling may contribute to signs of neuropathic pain. PMID:27841371

  9. Distribution of transmembrane AMPA receptor regulatory protein (TARP) isoforms in the rat spinal cord.

    PubMed

    Larsson, M; Agalave, N; Watanabe, M; Svensson, C I

    2013-09-17

    The transmembrane α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor regulatory proteins (TARPs) are a family of auxiliary AMPA receptor subunits that differentially modulate trafficking and many functional properties of the receptor. To investigate which TARP isoforms may be involved in AMPA receptor-mediated spinal synaptic transmission, we have mapped the localization of five of the known TARP isoforms, namely γ-2 (also known as stargazin), γ-3, γ-4, γ-7 and γ-8, in the rat spinal cord. Immunoblotting showed expression of all isoforms in the spinal cord to varying degrees. At the light microscopic level, immunoperoxidase labeling of γ-4, γ-7 and γ-8 was found throughout spinal gray matter. In white matter, γ-4 and γ-7 immunolabeling was observed in astrocytic processes and in mature oligodendrocytes. In pepsin-treated spinal cord, γ-7 often colocalized with GluA2 immunopositive puncta in the deep dorsal horn as well as in the ventral horn, but not in the superficial dorsal horn. Postembedding immunogold labeling was further used to assess the synaptic localization of γ-2, γ-7 and γ-8 in the dorsal horn. Synaptic immunogold labeling of γ-2 was sparse throughout the dorsal horn, with some primary afferent synapses weakly labeled, whereas relatively strong γ-7 immunogold labeling was found at deep dorsal horn synapses, including at synapses formed by low-threshold mechanosensitive primary afferent terminals. Prominent immunogold labeling of γ-8 was frequently detected at synapses established by primary afferent fibers. The spinal localization patterns of TARP isoforms reported here suggest that AMPA receptors at spinal synaptic populations and in glial cells may exhibit different functional characteristics owing to differences in auxiliary subunit composition.

  10. Elucidation of target muscle and detailed development of dorsal motor neurons in chick embryo spinal cord.

    PubMed

    Kobayashi, Nobumi; Homma, Shunsaku; Okada, Tomoaki; Masuda, Tomoyuki; Sato, Noboru; Nishiyama, Keiji; Sakuma, Chie; Shimada, Takako; Yaginuma, Hiroyuki

    2013-09-01

    The avian cervical spinal cord includes motoneurons (MNs) that send their axons through the dorsal roots. They have been called dorsal motoneurons (dMNs) and assumed to correspond to MNs of the accessory nerve that innervate the cucullaris muscle (SAN-MNs). However, their target muscles have not been elucidated to date. The present study sought to determine the targets and the specific combination of transcription factors expressed by dMNs and SAN-MNs and to describe the detailed development of dMNs. Experiments with tracing techniques confirmed that axons of dMNs innervated the cucullaris muscle. Retrogradely labeled dMNs were distributed in the ventral horn of C3 and more caudal segments. In most cases, some dMNs were also observed in the C2 segment. It was also demonstrated that SAN-MNs existed in the ventral horn of the C1-2 segments and the adjacent caudal hindbrain. Both SAN-MNs and dMNs expressed Isl1 but did not express Isl2, MNR2, or Lhx3. Rather, these MNs expressed Phox2b, a marker for branchial motoneurons (brMNs), although the intensity of expression was weaker. Dorsal MNs and SAN-MNs were derived from the Nkx2.2-positive precursor domain and migrated dorsally. Dorsal MNs remain in the ventral domain of the neural tube, unlike brMNs in the brainstem. These results indicate that dMNs and SAN-MNs belong to a common MN population innervating the cucullaris muscle and also suggest that they are similar to brMNs of the brainstem, although there are differences in Phox2b expression and in the final location of each population. J. Comp. Neurol. 521: 2987-3002, 2013. © 2013 Wiley Periodicals, Inc.

  11. 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

  12. Peripheral and spinal GABAergic regulation of incisional pain in rats.

    PubMed

    Reichl, Sylvia; Augustin, Mirjam; Zahn, Peter K; Pogatzki-Zahn, Esther M

    2012-01-01

    Impairment of spinal GABAergic inhibition is demonstrated to contribute to pathologic chronic pain states. We investigated spinal and peripheral GABAergic regulation of incisional pain in rats. We found that intrathecal but not peripheral administration of muscimol (GABA-A receptor agonist) and baclofen (GABA-B receptor agonist) reduced mechanical and thermal hyperalgesia after plantar incision in rats. Nonevoked pain behavior after incision was unaffected by these agonists. Similarly, nociception in unincised rats was not reduced by the same dose of agonists. Thus, GABA-A and GABA-B receptors are involved in mediating incision-induced hyperalgesia (but not nonevoked pain). Intrathecal and systemic application of L-838,417, a subtype-selective benzodiazepine site agonist (α2, α3, α5), reduced mechanical and heat hyperalgesia after incision, indicating a role of these subunits in mediating incision-induced hyperalgesia. Interestingly, the effects of all agonists were more intense and prolonged on the day after surgery than on the day of incision. Similarly, spinally administered GABA-A and GABA-B antagonists increased pain behavior, again with a greater effect 1 day after incision. One possible explanation for this finding might be that an incision modulates GABA-mediated inhibition 1 day after incision. However, expression of GABA-A receptor subunits α2 and α3 and GABA-B receptor subunits within the dorsal horn of the spinal cord were unchanged after incision, indicating that receptor expression cannot explain a possible modulation of GABAergic inhibition after incision. Thus, other mechanisms need to be considered. In conclusion, GABA-A and GABA-B receptors are promising targets for postoperative, incisional pain in humans.

  13. 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

  14. Electrophysiological characterization of spontaneous recovery in deep dorsal horn interneurons after incomplete spinal cord injury.

    PubMed

    Rank, M M; Flynn, J R; Galea, M P; Callister, R; Callister, R J

    2015-09-01

    In the weeks and months following an incomplete spinal cord injury (SCI) significant spontaneous recovery of function occurs in the absence of any applied therapeutic intervention. The anatomical correlates of this spontaneous plasticity are well characterized, however, the functional changes that occur in spinal cord interneurons after injury are poorly understood. Here we use a T10 hemisection model of SCI in adult mice (9-10 wks old) combined with whole-cell patch clamp electrophysiology and a horizontal spinal cord slice preparation to examine changes in intrinsic membrane and synaptic properties of deep dorsal horn (DDH) interneurons. We made these measurements during short-term (4 wks) and long-term (10 wks) spontaneous recovery after SCI. Several important intrinsic membrane properties are altered in the short-term, but recover to values resembling those of uninjured controls in the longer term. AP discharge patterns are reorganized at both short-term and long-term recovery time points. This is matched by reorganization in the expression of voltage-activated potassium and calcium subthreshold-currents that shape AP discharge. Excitatory synaptic inputs onto DDH interneurons are significantly restructured in long-term SCI mice. Plots of sEPSC peak amplitude vs. rise times suggest considerable dendritic expansion or synaptic reorganization occurs especially during long-term recovery from SCI. Connectivity between descending dorsal column pathways and DDH interneurons is reduced in the short-term, but amplified in long-term recovery. Our results suggest considerable plasticity in both intrinsic and synaptic mechanisms occurs spontaneously in DDH interneurons following SCI and takes a minimum of 10 wks after the initial injury to stabilize.

  15. The medullary dorsal reticular nucleus as a relay for descending pronociception induced by the mGluR5 in the rat infralimbic cortex.

    PubMed

    David-Pereira, Ana; Sagalajev, Boriss; Wei, Hong; Almeida, Armando; Pertovaara, Antti; Pinto-Ribeiro, Filipa

    2017-05-04

    Metabotropic glutamate receptor 5 (mGluR5) activation in the infralimbic cortex (IL) induces pronociceptive behavior in healthy and monoarthritic rats. Here we studied whether the medullary dorsal reticular nucleus (DRt) and the spinal TRPV1 are mediating the IL/mGluR5-induced spinal pronociception and whether the facilitation of pain behavior is correlated with changes in spinal dorsal horn neuron activity. For drug administrations, all animals had a cannula in the IL as well as a cannula in the DRt or an intrathecal catheter. Heat-evoked paw withdrawal was used to assess pain behavior in awake animals. Spontaneous and heat-evoked discharge rates of single DRt neurons or spinal dorsal horn wide-dynamic range (WDR) and nociceptive-specific (NS) neurons were evaluated in lightly anesthetized animals. Activation of the IL/mGluR5 facilitated nociceptive behavior in both healthy and monoarthritic animals, and this effect was blocked by lidocaine or GABA receptor agonists in the DRt. IL/mGluR5 activation increased spontaneous and heat-evoked DRt discharge rates in healthy but not monoarthritic rats. In the spinal dorsal horn, IL/mGluR5 activation increased spontaneous activity of WDR neurons in healthy animals only, whereas heat-evoked responses of WDR and NS neurons were increased in both experimental groups. Intrathecally administered TRPV1 antagonist prevented the IL/mGluR5-induced pronociception in both healthy and monoarthritic rats. The results suggest that the DRt is involved in relaying the IL/mGluR5-induced spinal pronociception in healthy control but not monoarthritic animals. Spinally, the IL/mGluR5-induced behavioral heat hyperalgesia is mediated by TRPV1 and associated with facilitated heat-evoked responses of WDR and NS neurons.

  16. A horizontal slice preparation for examining the functional connectivity of dorsal column fibres in mouse spinal cord.

    PubMed

    Flynn, Jamie R; Brichta, Alan M; Galea, Mary P; Callister, Robert J; Graham, Brett A

    2011-09-15

    In spinal cord injury (SCI) research, axon regeneration across spinal lesions is most often assessed using anatomical methods. It would be extremely advantageous, however, to examine the functional synaptic connectivity of regenerating fibres, using high-resolution electrophysiological methods. We have therefore developed a mouse horizontal spinal cord slice preparation that permits detailed analysis of evoked dorsal column (DCol) synaptic inputs on spinal neurons, using whole-cell patch clamp electrophysiology. This preparation allows us to characterise postsynaptic currents and potentials in response to electrical stimulation of DCol fibres, along with the intrinsic properties of spinal neurons. In addition, we demonstrate that low magnification calcium imaging can be used effectively to survey the spread of excitation from DCol stimulation in horizontal slices. This preparation is a potentially valuable tool for SCI research where confirmation of regenerated, functional synapses across a spinal lesion is critical.

  17. Information to cerebellum on spinal motor networks mediated by the dorsal spinocerebellar tract

    PubMed Central

    Stecina, Katinka; Fedirchuk, Brent; Hultborn, Hans

    2013-01-01

    The main objective of this review is to re-examine the type of information transmitted by the dorsal and ventral spinocerebellar tracts (DSCT and VSCT respectively) during rhythmic motor actions such as locomotion. Based on experiments in the 1960s and 1970s, the DSCT was viewed as a relay of peripheral sensory input to the cerebellum in general, and during rhythmic movements such as locomotion and scratch. In contrast, the VSCT was seen as conveying a copy of the output of spinal neuronal circuitry, including those circuits generating rhythmic motor activity (the spinal central pattern generator, CPG). Emerging anatomical and electrophysiological information on the putative subpopulations of DSCT and VSCT neurons suggest differentiated functions for some of the subpopulations. Multiple lines of evidence support the notion that sensory input is not the only source driving DSCT neurons and, overall, there is a greater similarity between DSCT and VSCT activity than previously acknowledged. Indeed the majority of DSCT cells can be driven by spinal CPGs for locomotion and scratch without phasic sensory input. It thus seems natural to propose the possibility that CPG input to some of these neurons may contribute to distinguishing sensory inputs that are a consequence of the active locomotion from those resulting from perturbations in the external world. PMID:23613538

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

    PubMed

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

    2014-01-01

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

  19. Age-dependent effects of peripheral inflammation on the electrophysiological properties of neonatal rat dorsal horn neurons.

    PubMed

    Torsney, Carole; Fitzgerald, Maria

    2002-03-01

    The aim of this study was to investigate the postnatal development of spinal cord neurophysiological mechanisms of inflammatory pain. The effect of hindpaw inflammation on the properties of neonatal spinal dorsal horn cells was investigated in urethane-anesthetized newborn rats using in vivo single-unit extracellular recordings. Responses to cutaneous mechanical and electrical A and C fiber stimulation were recorded at postnatal day (P) 3, 10, and 21 in pups that had received a unilateral intraplantar carageenan injection (1%, 1 microl/g body wt) 2-5 h earlier and compared with age-matched controls. At all three ages, carageenan inflammation increased A fiber evoked sensitization, spontaneous activity, and the suprathreshold response magnitude of dorsal horn cells. Receptive field size, which normally decreases with postnatal age, was unaffected by inflammation in P3 and P10 pups but significantly increased at P21 so that the size distribution closely resembled that in control P3 pups. Mechanical thresholds of individual dorsal horn neurons were not altered by carageenan inflammation at any age. The results show that some dorsal horn cell properties that are likely to underlie inflammatory hypersensitivity such as increased spontaneous activity and response magnitude are observed from the earliest postnatal age examined (P3). However inflammation induced expansion of mechanical receptive field size is not observed until at least the second postnatal week. These results have implications for the postnatal processing of inflammatory pain.

  20. 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

  1. Regeneration of lumbar dorsal root axons into the spinal cord of adult frogs (Rana pipiens), an HRP study.

    PubMed

    Liuzzi, F J; Lasek, R J

    1985-02-22

    Lumbar dorsal roots of adult frogs were crushed or cut and reanastomosed. Following survival times of up to 75 days, the regenerating dorsal roots were recut and anterogradely injury-filled with horseradish peroxidase. This revealed that in the adult frog, regenerating axons re-enter the spinal cord. Comparison of the distribution of these axons with that of normal dorsal root axons showed that there is a partial restoration of the segmental distribution in the gray matter. However, the long ascending sensory tract of the dorsal funiculus was not restored. The dorsal funiculus was markedly gliotic and had relatively few labelled, regenerated axons. The labelled axons that were seen in the dorsal funiculus either extended longitudinally for a distance just beneath the pia, apparently in association with the glia limitans, or traversed the region to enter the dorsal gray matter. Most of the large and small diameter axons that entered the gray matter did so by passing through the region of the dorsolateral fasciculus. Within the gray matter, small diameter, regenerated axons arborized in the region of the dorsal terminal field, a region that has been shown in the normal frog to receive cutaneous afferents only. Many large diameter axons, presumably muscle afferents, arborized in the ventral terminal field, a region shown in the normal frog to receive muscle afferents exclusively. However, many of these large diameter axons had arborizations that extended to both terminal fields, thus suggesting that some abberant connections are made during dorsal root regeneration in the adult frog.

  2. Origin and central projections of rat dorsal penile nerve: possible direct projection to autonomic and somatic neurons by primary afferents of nonmuscle origin.

    PubMed

    Núñez, R; Gross, G H; Sachs, B D

    1986-05-22

    Cell number, size, and somatotopic arrangement within the spinal ganglia of the cells of origin of the rat dorsal penile nerve (DPN), and their spinal cord projections, were studied by loading the proximal stump of the severed DPN with horseradish peroxidase (HRP). The DPN sensory cells were located entirely in the sixth lumbar (L6) dorsal root ganglia (DRG), in which a mean of 468 +/- 78 cells per side were observed, measuring 26.7 +/- 0.8 microns in their longest axis (range 10-65 microns) and distributed apparently randomly within the ganglia. Within the spinal cord, no retrograde label was found, i.e., no motoneurons were labeled, indicating that in the rat the DPN is formed exclusively of sensory nerve fibers. Although labeled fibers entered the cord only through L6, transganglionically transported HRP was evident in all spinal segments examined, i.e., T13-S2. Labeled fibers projected along the inner edge of the dorsal horn (medial pathway) throughout their extensive craniosacral distribution. However, laminar distribution varied with spinal segment. In the dorsal horn, terminals or preterminal axons were found in the dorsal horn marginal zone (lamina I), the substantia gelatinosa (lamina II), the nucleus proprius (laminae III and IV--the most consistent projection), Clarke's column (lamina VI), and the dorsal gray commissure. In the ventral horn, terminals were found in lamina VII and lamina IX. Label apposed to cell somas and dendrites in lamina VII may represent direct primary afferent projections onto sympathetic autonomic neurons. In lamina IX, labeled terminals delineated the somas and dendrites of cells that appeared to be motoneurons. This is the first description of an apparently monosynaptic contact onto motoneurons by a primary afferent of nonmuscle origin.

  3. Bilateral Cervical Contusion Spinal Cord Injury in Rats

    PubMed Central

    Anderson, Kim D.; Sharp, Kelli G.; Steward, Oswald

    2009-01-01

    There is increasing motivation to develop clinically relevant experimental models for cervical SCI in rodents and techniques to assess deficits in forelimb function. Here we describe a bilateral cervical contusion model in rats. Female Sprague-Dawley rats received mild or moderate cervical contusion injuries (using the Infinite Horizons device) at C5, C6, or C7/8. Forelimb motor function was assessed using a Grip Strength Meter (GSM); sensory function was assessed by the von Frey hair test; the integrity of the corticospinal tract (CST) was assessed by biotinylated dextran amine (BDA) tract tracing. Mild contusions caused primarily dorsal column (DC) and gray matter (GM) damage while moderate contusions produced additional damage to lateral and ventral tissue. Forelimb and hindlimb function was severely impaired immediately post-injury, but all rats regained the ability to use their hindlimbs for locomotion. Gripping ability was abolished immediately after injury but recovered partially, depending upon the spinal level and severity of the injury. Rats exhibited a loss of sensation in both fore- and hindlimbs that partially recovered, and did not exhibit allodynia. Tract tracing revealed that the main contingent of CST axons in the DC was completely interrupted in all but one animal whereas the dorsolateral CST (dlCST) was partially spared, and dlCST axons gave rise to axons that arborized in the GM caudal to the injury. Our data demonstrate that rats can survive significant bilateral cervical contusion injuries at or below C5 and that forepaw gripping function recovers after mild injuries even when the main component of CST axons in the dorsal column is completely interrupted. PMID:19559699

  4. 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

  5. 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.

  6. Activity-dependent dephosphorylation of paxillin contributed to nociceptive plasticity in spinal cord dorsal horn.

    PubMed

    Wang, Xin-Tai; Zheng, Rui; Suo, Zhan-Wei; Liu, Yan-Ni; Zhang, Zi-Yang; Ma, Zheng-An; Xue, Ye; Xue, Man; Yang, Xian; Hu, Xiao-Dong

    2016-03-01

    The enzymatic activity of protein tyrosine kinase Src is subjected to the regulation by C-terminal Src kinase (CSK) and protein tyrosine phosphatases (PTPs). Aberrant Src activation in the spinal cord dorsal horn is pivotal for the induction and development of nociceptive behavioral sensitization. In this study, we found that paxillin, one of the well-characterized cell adhesion components involved in cell migration and survival, integrated CSK and PTPs' signaling to regulate Src-dependent nociceptive plasticity. Paxillin localized at excitatory glutamatergic synapses in the spinal dorsal horn of mice, and the phosphorylation of Tyr118 on paxillin was necessary to associate with and target CSK at synapses. After peripheral tissue injury, the enhanced neuronal activity stimulated N-methyl-D-aspartate (NMDA) subtype glutamate receptors, which initiated PTPs' signaling to catalyze Tyr118 dephosphorylation. The reduced Tyr118 phosphorylation disrupted paxillin interaction with CSK, leading to the dispersal of CSK out of synapses. With the loss of CSK-mediated inhibition, Src activity was persistently increased. The active Src potentiated the synaptic transmission specifically mediated by GluN2B subunit-containing NMDA receptors. The active Src also facilitated the induction of long-term potentiation of C fiber-evoked field potentials and exaggerated painful responses. In complete Freund's adjuvant-injected mice, viral expression of phosphomimicking paxillin mutant to resume CSK synaptic localization repressed Src hyperactivity. Meanwhile, this phosphomimicking paxillin mutant blunted NMDA receptor-mediated synaptic transmission and alleviated chronic inflammatory pain. These data showed that PTPs-mediated dephosphorylation of paxillin at Tyr118 was involved in the modification of nociceptive plasticity through CSK-Src signaling.

  7. Microvascular Fragment Transplantation Improves Rat Dorsal Skin Flap Survival

    PubMed Central

    Rathbone, Christopher R.

    2016-01-01

    Background: The development of flap necrosis distally remains a concern during microsurgical flap transfers because, at least in part, of decreased perfusion. Microvascular fragments (MVFs) are microvessels isolated from adipose tissue that are capable of improving tissue perfusion in a variety of tissue defects. The aim of this study was to determine whether the transplantation of MVFs in a dorsal rat skin flap model can improve flap survival. Methods: A 10 × 3 cm flap was raised in a cranial to caudal fashion on the dorsal side of 16 Lewis rats, with the caudal side remaining intact. The rats were equally divided into a treatment group (MVFs) and a control group (sterile saline). At the time of surgery, sterile saline with or without MVFs was injected directly into the flap. Microvessel density was determined after harvesting flap tissue by counting vessels that positively stained for Griffonia simplicifolia lectin I-isolectin B4. Laser Doppler was used to measure blood flow before and after surgery and 7 and 14 days later. Flap survival was evaluated 7 and 14 days after surgery by evaluating the percentage of viable tissue of the flap with photodigital planimetry. Results: Despite the lack of a significant difference in microvessel density and tissue perfusion, flap survival increased 6.4% (P < 0.05) in MVF-treated animals compared with controls. Conclusions: The use of MVFs may be a means to improve flap survival. Future studies are required to delineate mechanisms whereby this occurs and to further optimize their application. PMID:28293502

  8. Pelvic nerve input mediates descending modulation of homovisceral processing in the thoracolumbar spinal cord of the rat

    PubMed Central

    Wang, Gexin; Tang, Bin; Traub, Richard J.

    2007-01-01

    Background and aims Colonic afferents project to the lumbosacral and thoracolumbar spinal cord via the pelvic and hypogastric/lumbar colonic nerves, respectively. Both spinal regions process inflammatory colonic stimuli. The role of thoracolumbar segments in processing acute colorectal pain is questionable, however, since the lumbosacral spinal cord appears sufficient to process reflex responses to acute pain. Here we demonstrate that activity in pelvic nerve colonic afferents actively modulates thoracolumbar dorsal horn neuron processing of the same colonic stimulus via a supraspinal loop: homovisceral descending modulation. Methods Dorsal horn neurons were recorded in the rat thoracolumbar spinal cord following acute or chronic pelvic neurectomy and cervical cold block. Results Acute pelvic neurectomy or lidocaine inhibition of lumbosacral dorsal roots facilitated the excitatory response of thoracolumbar dorsal horn neurons to colorectal distention (CRD) and decreased the percentage of neurons inhibited by CRD, suggesting colonic input over the pelvic nerve inhibits thoracolumbar processing of the same stimulus. Ectopic activity developed in the proximal pelvic nerve following chronic neurectomy reactivating the inhibitory circuit, inhibiting thoracolumbar neurons. Cervical cold block alleviated the inhibition in intact or chronic neurectomized rats. However, the facilitated response following acute pelvic neurectomy was inhibited by cervical cold block exposing an underlying descending facilitation. Inhibiting pelvic nerve input following cervical cold block had minimal effect. Conclusion These data demonstrate that input over the pelvic nerve modulates the response of thoracolumbar spinal neurons to CRD via a supraspinal loop, and that increasing thoracolumbar processing increases visceral hyperalgesia. PMID:17916357

  9. Intersegmental synchronization of spontaneous activity of dorsal horn neurons in the cat spinal cord.

    PubMed

    Manjarrez, E; Jiménez, I; Rudomin, P

    2003-02-01

    Extracellular recordings of neuronal activity made in the lumbosacral spinal segments of the anesthetized cat have disclosed the existence of a set of neurons in Rexed's laminae III-VI that discharged in a highly synchronized manner during the occurrence of spontaneous negative cord dorsum potentials (nCDPs) and responded to stimulation of low-threshold cutaneous fibers (<1.5x T) with mono- and polysynaptic latencies. The cross-correlation between the spontaneous discharges of pairs of synchronic neurons was highest when they were close to each other, and decreased with increasing longitudinal separation. Simultaneous recordings of nCDPs from several segments in preparations with the peripheral nerves intact have disclosed the existence of synchronized spontaneous nCDPs in segments S1-L4. These potentials lasted between 25 and 70 ms and were usually larger in segments L7-L5, where they attained amplitudes between 50 and 150 micro V. The transection of the intact ipsilateral hindlimb cutaneous and muscle nerves, or the section of the dorsal columns between the L5 and L6, or between the L6 and L7 segments in preparations with already transected nerves, had very small effects on the intersegmental synchronization of the spontaneous nCDPs and on the power spectra of the cord dorsum potentials recorded in the lumbosacral enlargement. In contrast, sectioning the ipsilateral dorsal horn and the dorsolateral funiculus at these segmental levels strongly decoupled the spontaneous nCDPs generated rostrally from those generated caudally to the lesion and reduced the magnitude of the power spectra throughout the whole frequency range. These results indicate that the lumbosacral intersegmental synchronization between the spontaneous nCDPs does not require sensory inputs and is most likely mediated by intra- and intersegmental connections. It is suggested that the occurrence of spontaneous synchronized nCDPs is due to the activation of tightly coupled arrays of neurons, each

  10. Effects of combined electrical stimulation of the dorsal column and dorsal roots on wide-dynamic range neuronal activity in nerve-injured rats

    PubMed Central

    Yang, Fei; Zhang, Tong; Tiwari, Vinod; Shu, Bin; Zhang, Chen; Wang, Yun; Vera-Portocarrero, Louis P.; Raja, Srinivasa N.; Guan, Yun

    2015-01-01

    Objectives Electrical stimulation at the dorsal column (DC) and dorsal root (DR) may inhibit spinal wide-dynamic-range (WDR) neuronal activity in nerve-injured rats. The objective of this study was to determine if applying electrical conditioning stimulation (CS) at both sites provides additive or synergistic benefits. Materials and Methods By conducting in vivo extracellular recordings of WDR neurons in rats that had undergone L5 spinal nerve ligation, we tested whether combining 50 Hz CS at the two sites in either a concurrent (2.5 minutes) or alternate (5 minutes) pattern inhibits WDR neuronal activity better than CS at DC alone (5 minutes). The intensities of CS were determined by recording antidromic compound action potentials to graded stimulation at the DC and DR. We measured the current thresholds that resulted in the first detectable Aα/β waveform (Ab0) and the peak Aα/β waveform (Ab1) to select CS intensity at each site. The same number of electrical pulses and amount of current were delivered in different patterns to allow comparison. Results At a moderate intensity of 50%(Ab0+Ab1), different patterns of CS all attenuated the C-component of WDR neurons in response to graded intracutaneous electrical stimuli (0.1-10 mA, 2 ms), and inhibited windup in response to repetitive noxious stimuli (0.5 Hz). However, the inhibitory effects did not differ significantly between different patterns. At the lower intensity (Ab0), no CS inhibited WDR neurons. Conclusions These findings suggest that combined stimulation of DC and DR may not be superior to DC stimulation alone for inhibition of WDR neurons. PMID:26307526

  11. Pannexin 1: a novel participant in neuropathic pain signaling in the rat spinal cord.

    PubMed

    Bravo, David; Ibarra, Paula; Retamal, Jeffri; Pelissier, Teresa; Laurido, Claudio; Hernandez, Alejandro; Constandil, Luis

    2014-10-01

    Pannexin 1 (panx1) is a large-pore membrane channel expressed in many tissues of mammals, including neurons and glial cells. Panx1 channels are highly permeable to calcium and adenosine triphosphatase (ATP); on the other hand, they can be opened by ATP and glutamate, two crucial molecules for acute and chronic pain signaling in the spinal cord dorsal horn, thus suggesting that panx1 could be a key component for the generation of central sensitization during persistent pain. In this study, we examined the effect of three panx1 blockers, namely, 10panx peptide, carbenoxolone, and probenecid, on C-reflex wind-up activity and mechanical nociceptive behavior in a spared nerve injury neuropathic rat model involving sural nerve transection. In addition, the expression of panx1 protein in the dorsal horn of the ipsilateral lumbar spinal cord was measured in sural nerve-transected and sham-operated control rats. Sural nerve transection resulted in a lower threshold for C-reflex activation by electric stimulation of the injured hindpaw, together with persistent mechanical hypersensitivity to pressure stimuli applied to the paw. Intrathecal administration of the panx1 blockers significantly depressed the spinal C-reflex wind-up activity in both neuropathic and sham control rats, and decreased mechanical hyperalgesia in neuropathic rats without affecting the nociceptive threshold in sham animals. Western blotting showed that panx1 was similarly expressed in the dorsal horn of lumbar spinal cord from neuropathic and sham rats. The present results constitute the first evidence that panx1 channels play a significant role in the mechanisms underlying central sensitization in neuropathic pain.

  12. Identification and characterization of a cell surface marker for embryonic rat spinal accessory motor neurons.

    PubMed

    Schubert, W; Kaprielian, Z

    2001-10-22

    The developing mammalian spinal cord contains distinct populations of motor neurons that can be distinguished by their cell body positions, by the expression of specific combinations of regulatory genes, and by the paths that their axons take to exit the central nervous system (CNS). Subclasses of spinal motor neurons are also thought to express specific cell surface proteins that function as receptors which control the guidance of their axons. We identified monoclonal antibody (mAb) SAC1 in a screen aimed at generating markers for specific subsets of neurons/axons in the developing rat spinal cord. During early embryogenesis, mAb SAC1 selectively labels a small subset of Isl1-positive motor neurons located exclusively within cervical segments of the spinal cord. Strikingly, these neurons extend mAb SAC1-positive axons along a dorsally directed trajectory toward the lateral exit points. Consistent with the finding that mAb SAC1 also labels spinal accessory nerves, these observations identify mAb SAC1 as a specific marker of spinal accessory motor neurons/axons. During later stages of embryogenesis, mAb SAC1 is transiently expressed on both dorsally and ventrally projecting spinal motor neurons/axons. Interestingly, mAb SAC1 also labels the notochord and floor plate during most stages of spinal cord development. The mAb SAC1 antigen is a 100-kD glycoprotein that is likely to be the rat homolog of SC1/BEN/DM-GRASP, a homophilic adhesion molecule that mediates axon outgrowth and fasciculation.

  13. Cortical Presynaptic Control of Dorsal Horn C–Afferents in the Rat

    PubMed Central

    Martínez-Lorenzana, Guadalupe; Condés-Lara, Miguel; Rojas-Piloni, Gerardo

    2013-01-01

    Lamina 5 sensorimotor cortex pyramidal neurons project to the spinal cord, participating in the modulation of several modalities of information transmission. A well-studied mechanism by which the corticospinal projection modulates sensory information is primary afferent depolarization, which has been characterized in fast muscular and cutaneous, but not in slow-conducting nociceptive skin afferents. Here we investigated whether the inhibition of nociceptive sensory information, produced by activation of the sensorimotor cortex, involves a direct presynaptic modulation of C primary afferents. In anaesthetized male Wistar rats, we analyzed the effects of sensorimotor cortex activation on post tetanic potentiation (PTP) and the paired pulse ratio (PPR) of dorsal horn field potentials evoked by C–fiber stimulation in the sural (SU) and sciatic (SC) nerves. We also explored the time course of the excitability changes in nociceptive afferents produced by cortical stimulation. We observed that the development of PTP was completely blocked when C-fiber tetanic stimulation was paired with cortex stimulation. In addition, sensorimotor cortex activation by topical administration of bicuculline (BIC) produced a reduction in the amplitude of C–fiber responses, as well as an increase in the PPR. Furthermore, increases in the intraspinal excitability of slow-conducting fiber terminals, produced by sensorimotor cortex stimulation, were indicative of primary afferent depolarization. Topical administration of BIC in the spinal cord blocked the inhibition of C–fiber neuronal responses produced by cortical stimulation. Dorsal horn neurons responding to sensorimotor cortex stimulation also exhibited a peripheral receptive field and responded to stimulation of fast cutaneous myelinated fibers. Our results suggest that corticospinal inhibition of nociceptive responses is due in part to a modulation of the excitability of primary C–fibers by means of GABAergic inhibitory

  14. [Anti-amphiphysin antibody-positive paraneoplastic neurological syndrome with a longitudinally extensive spinal cord lesion of the dorsal column].

    PubMed

    Neshige, Shuichiro; Hara, Naoyuki; Takeshima, Shinichi; Iwaki, Hirotaka; Shimoe, Yutaka; Takamatsu, Kazuhiro; Kuriyama, Masaru

    2014-01-01

    A 53-year-old woman was admitted to our hospital because of gait disturbance and paresthesia of the lower extremities. She also had marked deep sense impairment in her lower limbs. Cervical MRI showed a longitudinally extensive spinal cord lesion of the dorsal column at levels C1-T11. The findings of cerebrospinal fluid examination, including the IgG index (0.65), were normal. Serum anti-AQP4 antibody was negative, but anti-amphiphysin antibody was positive. Electrophysiological examinations suggested the presence of lesions in the dorsal column of the spinal cord and dorsal root ganglion (DRG). Enlargement of and fluorodeoxyglucose accumulation in her left parasternal lymph node was observed on contrast-enhanced CT and PET-CT, respectively. The lymph node biopsy was underwent by using thoracoscopy. The metastasis of carcinoma was pathologically confirmed. Although the primary tumor was not detected on PET-CT re-examination, immunostaining of the biopsied lymph node specimen was positive for both the progesterone receptor and estrogen receptor. On the basis of these findings, the patient was diagnosed with paraneoplastic neurological syndrome due to potential breast cancer. The disorder is an immunological subacute sensory neuropathy with a longitudinally extensive spinal cord lesion of the dorsal column and a DRG lesion.

  15. 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.

  16. Hemisection spinal cord injury in rat: the value of intraoperative somatosensory evoked potential monitoring.

    PubMed

    Cloud, Beth A; Ball, Bret G; Chen, Bingkun K; Knight, Andrew M; Hakim, Jeffrey S; Ortiz, Ana M; Windebank, Anthony J

    2012-11-15

    Techniques used to produce partial spinal cord injuries in animal models have the potential for creating variability in lesions. The amount of tissue affected may influence the functional outcomes assessed in the animals. The recording of somatosensory evoked potentials (SSEPs) may be a valuable tool for assessing the extent of lesion applied in animal models of traumatic spinal cord injury (SCI). Intraoperative tibial SSEP recordings were assessed during surgically induced lateral thoracic hemisection SCI in Sprague-Dawley rats. The transmission of SSEPs, or lack thereof, was determined and compared against the integrity of the dorsal funiculi on each side of the spinal cord upon histological sectioning. An association was found between the presence of an SSEP signal and presence of intact dorsal funiculus tissue. The relative risk is 4.50 (95% confidence interval: 1.83-11.08) for having an intact dorsal funiculus when the ipsilateral SSEP was present compared to when it was absent. Additionally, the amount of spared spinal cord tissue correlates with final functional assessments at nine weeks post injury: BBB (linear regression, R²=0.618, p<0.001) and treadmill test (linear regression, R²=0.369, p=0.016). Therefore, we propose intraoperative SSEP monitoring as a valuable tool to assess extent of lesion and reduce variability between animals in experimental studies of SCI.

  17. 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

  18. Recombinant DNA vaccine against inhibition of neurite outgrowth promotes functional recovery associated with endogeous NGF expression in spinal cord hemisected adult rats.

    PubMed

    Zhang, Yi; Hao, Chun-Guang; Hu, Li-Qun; Dong, Jian; Wei, Peng; Xu, Dan; Xiao, Zhi-Cheng; Wang, Ting-Hua

    2009-09-01

    Axonal regeneration across the site of spinal cord lesion is often aborted in adult mammalian species. The use of DNA vaccine to nullify the inhibitory molecules has been shown to be effective in promoting axonal regeneration in injured spinal cord. The possible molecular mechanisms, however, remain to be elucidated. The present study showed that the administration of recombinant DNA vaccine encoding multiple domains, Nogo-66, Nogo-N, TnR, and MAG, significantly improved hindlimb locomotor functions in rats subjected to ablation of the dorsal halves of the cord. Western blot analysis demonstrated that nerve growth factor (NGF) levels in the spinal cord of immunized rats were significantly upregulated than those of control rats. Immunohistochemistry as well as in situ hybridization confirmed that NGF was expressed in neurons of the spinal cord. These findings indicated that functional recovery in immunized rats could be correlated with endogeous NGF expression in hemisected rat spinal cords.

  19. Neuronal intrinsic properties shape naturally evoked sensory inputs in the dorsal horn of the spinal cord

    PubMed Central

    Reali, Cecilia; Russo, Raúl E.

    2013-01-01

    Intrinsic electrophysiological properties arising from specific combinations of voltage-gated channels are fundamental for the performance of small neural networks in invertebrates, but their role in large-scale vertebrate circuits remains controversial. Although spinal neurons have complex intrinsic properties, some tasks produce high-conductance states that override intrinsic conductances, minimizing their contribution to network function. Because the detection and coding of somato-sensory information at early stages probably involves a relatively small number of neurons, we speculated that intrinsic electrophysiological properties are likely involved in the processing of sensory inputs by dorsal horn neurons (DHN). To test this idea, we took advantage of an integrated spinal cord–hindlimbs preparation from turtles allowing the combination of patch-clamp recordings of DHN embedded in an intact network, with accurate control of the extracellular milieu. We found that plateau potentials and low threshold spikes (LTS) -mediated by L- and T-type Ca2+channels, respectively- generated complex dynamics by interacting with naturally evoked synaptic potentials. Inhibitory receptive fields could be changed in sign by activation of the LTS. On the other hand, the plateau potential transformed sensory signals in the time domain by generating persistent activity triggered on and off by brief sensory inputs and windup of the response to repetitive sensory stimulation. Our findings suggest that intrinsic properties dynamically shape sensory inputs and thus represent a major building block for sensory processing by DHN. Intrinsic conductances in DHN appear to provide a mechanism for plastic phenomena such as dynamic receptive fields and sensitization to pain. PMID:24399934

  20. Somatostatin inhibits activation of dorsal cutaneous primary afferents induced by antidromic stimulation of primary afferents from an adjacent thoracic segment in the rat.

    PubMed

    Guo, Yuan; Yao, Fan-Rong; Cao, Dong-Yuan; Pickar, Joel G; Zhang, Qi; Wang, Hui-Sheng; Zhao, Yan

    2008-09-10

    To investigate the effect of somatostatin on the cross-excitation between adjacent primary afferent terminals in the rats, we recorded single unit activity from distal cut ends of dorsal cutaneous branches of the T10 and T12 spinal nerves in response to antidromic stimulation of the distal cut end of the T11 dorsal root in the presence and absence of somatostatin and its receptor antagonist applied to the receptive field of the recorded nerve. Afferent fibers were classified based upon their conduction velocity. Mean mechanical thresholds decreased and spontaneous discharge rates increased significantly in C and Adelta but not Abeta fibers of the T10 and T12 spinal nerves in both male and female rats following antidromic electrical stimulation (ADES) of the dorsal root from adjacent spinal segment (DRASS) indicating cross-excitation of thin fiber afferents. The cross-excitation was not significantly different between male and female rats. Microinjection of somatostatin into the receptive field of recorded units inhibited the cross-excitation. This inhibitory effect, in turn, was reversed by the somatostation receptor antagonist cyclo-somatostatin (c-SOM). Application of c-SOM alone followed by ADES of DRASS significantly decreased the mechanical thresholds and increased the discharge rates of C and Adelta fibers, indicating that endogenous release of somatostatin plays a tonic inhibitory role on the cross-excitation between peripheral nerves. These results suggest that somatostatin could inhibit the cross-excitation involved in peripheral hyperalgesia and have a peripheral analgesic effect.

  1. Upper thoracic postsynaptic dorsal column neurons conduct cardiac mechanoreceptive information, but not cardiac chemical nociception in rats.

    PubMed

    Goodman-Keiser, Melanie D; Qin, Chao; Thompson, Ann M; Foreman, Robert D

    2010-12-17

    Postsynaptic dorsal column (PSDC) neurons transmit noxious visceral information from the lower thoracic and lumbosacral spinal cord. Cuneothalamic neurons in the PSDC pathway and upper thoracic (T(3)-T(4)) spinal neurons ascending through the ventrolateral funiculus (VLF) have been shown to transmit nociceptive cardiac information. Therefore, we hypothesized that upper thoracic PSDC neurons transmit noxious cardiac information. Neuronal responses to intrapericardially injected mechanical (1.0 ml saline) and noxious chemical (0.2 ml algogenic chemicals) stimuli were recorded from antidromically activated PSDC and VLF neurons in the T(3)-T(4) spinal cord of anesthetized Sprague-Dawley rats. Of the PSDC neurons, 43% responded to mechanical stimulation, but only one responded to noxious chemical stimuli. Fifty-eight percent of VLF neurons responded to mechanical stimulation and all responded to noxious chemical stimulation. Fluoro-Ruby (FR)-labeled PSDC neurons in the T(3)-T(4) spinal cord of Sprague-Dawley rats were processed for c-fos immunohistochemistry following intrapericardial stimulation with mechanical, chemical, or control stimuli. Sections were viewed under epifluorescence and light microscopy to detect FR-labeled neurons containing a c-fos immunoreactive (IR) nucleus. An average of 6 PSDC neurons per rat was found in the T(3) and T(4) spinal segments. The average number of c-fos-IR neurons per segment varied by type of stimulus: 12 (control), 67 (chemical) and 85 (mechanical) for T(3) and 8 (control), 37 (chemical) and 62 (mechanical) for T(4). None of the 200 PSDC neurons examined expressed c-fos-IR regardless of stimulus. Together, these results suggest that thoracic PSDC neurons transmit mechanical cardiac information, but they play a minimal role in cardiac nociception.

  2. 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.

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

    PubMed Central

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

    2017-01-01

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

  4. Crosstalk between Activated Microglia and Neurons in the Spinal Dorsal Horn Contributes to Stress-induced Hyperalgesia

    PubMed Central

    Qi, Jian; Chen, Chen; Meng, Qing-Xi; Wu, Yan; Wu, Haitao; Zhao, Ting-Bao

    2016-01-01

    Stress has been shown to enhance pain sensitivity resulting in stress-induced hyperalgesia. However, the underlying mechanisms have yet to be elucidated. Using single-prolonged stress combined with Complete Freund’s Adjuvant injection model, we explored the reciprocal regulatory relationship between neurons and microglia, which is critical for the maintenance of posttraumatic stress disorder (PTSD)-induced hyperalgesia. In our assay, significant mechanical allodynia was observed. Additionally, activated neurons in spinal dorsal horn were observed by analysis of Fos expression. And, microglia were also significantly activated with the presence of increased Iba-1 expression. Intrathecal administration of c-fos antisense oligodeoxynucleotides (ASO) or minocycline (a specific microglia inhibitor) attenuated mechanical allodynia. Moreover, intrathecal administration of c-fos ASO significantly suppressed the activation of neurons and microglia. Interestingly, inhibition of microglia activation by minocycline significantly suppressed the activation of both neurons and microglia in spinal dorsal horn. P38 inhibitor SB203580 suppressed IL-6 production, and inhibition of IL-6 receptor (IL-6R) activation by tocilizumab suppressed Fos expression. Together, our data suggest that the presence of a “crosstalk” between activated microglia and neurons in the spinal dorsal horn, which might contribute to the stress-induced hyperactivated state, leading to an increased pain sensitivity. PMID:27995982

  5. 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

  6. Peripheral nerve injury produces a sustained shift in the balance between glutamate release and uptake in the dorsal horn of the spinal cord

    PubMed Central

    Inquimbert, Perrine; Bartels, Karsten; Babaniyi, Olusegun B.; Barrett, Lee B.; Tegeder, Irmgard; Scholz, Joachim

    2012-01-01

    Peripheral nerve injury provokes heightened excitability of primary sensory afferents including nociceptors, and elicits ectopic activity in lesioned and neighboring intact nerve fibers. The major transmitter released by sensory afferents in the superficial dorsal horn of the spinal cord is glutamate. Glutamate is critically involved in nociceptive signaling and the development of neuropathic pain. We recorded miniature excitatory postsynaptic currents (mEPSCs) from neurons in lamina II of the rat dorsal horn to assess spontaneous synaptic activity after spared nerve injury (SNI), a model of chronic neuropathic pain. Following SNI, the frequency of mEPSCs doubled, indicating heightened glutamate release from primary afferents or spinal interneurons. Consistent with this finding, glutamate concentrations in the cerebrospinal fluid were elevated at one and four weeks after SNI. Transmitter uptake was insufficient to prevent the rise in extracellular glutamate as the expression of glutamate transporters remained unchanged or decreased. 2-Methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP), an antagonist of metabotropic glutamate receptor 5 (mGluR5), reduced the frequency of mEPSCs to its preinjury level, suggesting a positive feedback mechanism that involves facilitation of transmitter release by mGluR5 activation in the presence of high extracellular glutamate. Treatment with the β-lactam antibiotic ceftriaxone increased the expression of glutamate transporter 1 (Glt1) in the dorsal horn after SNI, raised transmitter uptake and lowered extracellular glutamate. Improving glutamate clearance prevented the facilitation of transmitter release by mGluR5 and attenuated neuropathic pain-like behavior. Balancing glutamate release and uptake after nerve injury should be an important target in the management of chronic neuropathic pain. PMID:23021150

  7. Role of spinal 5-HT5A, and 5-HT1A/1B/1D, receptors in neuropathic pain induced by spinal nerve ligation in rats.

    PubMed

    Avila-Rojas, Sabino Hazael; Velázquez-Lagunas, Isabel; Salinas-Abarca, Ana Belen; Barragán-Iglesias, Paulino; Pineda-Farias, Jorge Baruch; Granados-Soto, Vinicio

    2015-10-05

    Serotonin (5-HT) participates in pain modulation by interacting with different 5-HT receptors. The role of 5-HT5A receptor in neuropathic pain has not previously studied. The purpose of this study was to investigate: A) the role of 5-HT5A receptors in rats subjected to spinal nerve injury; B) the expression of 5-HT5A receptors in dorsal spinal cord and dorsal root ganglia (DRG). Neuropathic pain was induced by L5/L6 spinal nerve ligation. Tactile allodynia in neuropathic rats was assessed with von Frey filaments. Western blot methodology was used to determine 5-HT5A receptor protein expression. Intrathecal administration (on day 14th) of 5-HT (10-100 nmol) or 5-carboxamidotryptamine (5-CT, 0.03-0.3 nmol) reversed nerve injury-induced tactile allodynia. Intrathecal non-selective (methiothepin, 0.1-0.8 nmol) and selective (SB-699551, 1-10 nmol) 5-HT5A receptor antagonists reduced, by ~60% and ~25%, respectively, the antiallodynic effect of 5-HT (100 nmol) or 5-CT (0.3 nmol). Moreover, both selective 5-HT1A and 5-HT1B/1D receptor antagonists, WAY-100635 (0.3-1 nmol) and GR-127935 (0.3-1 nmol), respectively, partially diminished the antiallodynic effect of 5-HT or 5-CT by about 30%. Injection of antagonists, by themselves, did not affect allodynia. 5-HT5A receptors were expressed in the ipsilateral dorsal lumbar spinal cord and DRG and L5/L6 spinal nerve ligation did not modify 5-HT5A receptor protein expression in those sites. Results suggest that 5-HT5A receptors reduce pain processing in the spinal cord and that 5-HT and 5-CT reduce neuropathic pain through activation of 5-HT5A and 5-HT1A/1B/1D receptors. These receptors could be an important part of the descending pain inhibitory system.

  8. In vivo single unit extracellular recordings from spinal cord neurones of rats.

    PubMed

    Urch, C E; Dickenson, A H

    2003-08-01

    A method for in vivo single unit extracellular recordings from the dorsal horn of rat or mouse spinal cords is described. This method allows the complex, dynamic and plastic circuitry of the dorsal horn to be explored in various models and situations. Briefly, the spinal cord is exposed in deeply anaesthetised animals and a recording electrode is inserted into the dorsal horn. To isolate a neurone the electrode is moved incrementally through the cord whilst the ipsilateral hindpaw (receptive field) is stimulated with a light tap. The neurone can then be characterised according to its depth, latency of Abeta-, Adelta- and C-fibre responses and its response to natural (brush, heat, pressure) and electrical stimulation. The neuronal response is captured, filtered, amplified and displayed via an oscilloscope and speakers, and fed through to a computer where the responses can be integrated and displayed in numerous formats. This basic technique can be adapted to record from animals of various ages, to investigate alterations in spinal processing, suprapsinal influences, receptive field size and so on, and to assess the impact of therapeutic or other interventions. A key issue is that this type of approach, unlike behavioural assessment that relies on threshold measures, allows quantitative measures of suprathreshold activity, closer to the clinical situation.

  9. A mixed Ca2+ channel blocker, A-1264087, utilizes peripheral and spinal mechanisms to inhibit spinal nociceptive transmission in a rat model of neuropathic pain.

    PubMed

    Xu, Jun; Chu, Katharine L; Zhu, Chang Z; Niforatos, Wende; Swensen, Andrew; Searle, Xenia; Lee, Lance; Jarvis, Michael F; McGaraughty, Steve

    2014-01-01

    N-, T- and P/Q-type voltage-gated Ca(2+) channels are critical for regulating neurotransmitter release and cellular excitability and have been implicated in mediating pathological nociception. A-1264087 is a novel state-dependent blocker of N-, T- and P/Q-type channels. In the present studies, A-1264087 blocked (IC50 = 1.6 μM) rat dorsal root ganglia N-type Ca(2+) in a state-dependent fashion. A-1264087 (1, 3 and 10 mg/kg po) dose-dependently reduced mechanical allodynia in rats with a spinal nerve ligation (SNL) injury. A-1264087 (4 mg/kg iv) inhibited both spontaneous and mechanically evoked activity of spinal wide dynamic range (WDR) neurons in SNL rats but had no effect in uninjured rats. The inhibitory effect on WDR neurons remained in spinally transected SNL rats. Injection of A-1264087 (10 nmol/0.5 μl) into the spinal cord reduced both spontaneous and evoked WDR activity in SNL rats. Application of A-1264087 (300 nmol/20 μl) into the receptive field on the hindpaw attenuated evoked but not spontaneous firing of WDR neurons. Using electrical stimulation, A-1264087 (4 mg/kg iv) inhibited Aδ- and C-fiber evoked responses and after-discharge of WDR neurons in SNL rats. These effects by A-1264087 were not present in uninjured rats. A-1264087 moderately attenuated WDR neuron windup in both uninjured and SNL rats. In summary, these results indicate that A-1264087 selectively inhibited spinal nociceptive transmission in sensitized states through both peripheral and central mechanisms.

  10. Mechanisms of GABA and glycine depolarization-induced calcium transients in rat dorsal horn neurons.

    PubMed Central

    Reichling, D B; Kyrozis, A; Wang, J; MacDermott, A B

    1994-01-01

    1. The mechanisms and effects of GABA- and glycine-evoked depolarization were studied in cultured rat dorsal horn neurons using indo-1 recordings of [Ca2+]i and patch clamp recordings in conventional whole-cell or perforated-patch mode. 2. Application of GABA to unclamped neurons caused [Ca2+]i increases that were dose dependent and exhibited GABAA receptor pharmacology. Calcium entered the neurons via high-threshold voltage-gated calcium channels (conotoxin and nimodipine sensitive). 3. In perforated-patch recordings employing cation-selective ionophores, GABAA receptor activation depolarized 123 of 132 cells to membrane potentials as depolarized as -33 mV (mean -50 mV in all 132 cells, +12 mV above resting potential). The ionic basis of the depolarization was determined by extracellular ion substitution; increased anionic conductance could account fully for the results. 4. Glycine, acting at a strychnine-sensitive receptor, also caused Ca2+ entry into these neurons through voltage-gated Ca2+ channels. Glycine and GABA both evoked [Ca2+]i responses in the same cells and the responses were highly correlated in amplitude. Glycine also depolarized all five cells tested with perforated recording. Each of the five cells was also depolarized by muscimol to a value similar to that obtained for glycine. 5. Both the depolarization and the increases in [Ca2+]i caused by GABA and glycine could potentially play a role in processes of development and differentiation and sensory transmission in the spinal cord dorsal horn. PMID:8057250

  11. 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.

  12. Treadmill exercise facilitates recovery of locomotor function through axonal regeneration following spinal cord injury in rats

    PubMed Central

    Jung, Sun-Young; Seo, Tae-Beom; Kim, Dae-Young

    2016-01-01

    Spinal cord injury (SCI) disrupts both axonal pathways and segmental spinal cord circuity, resulting in permanent neurological deficits. Physical exercise is known to increase the expression of neurotrophins for improving the injured spinal cord. In the present study, we investigated the effects of treadmill exercise on locomotor function in relation with brain-derived neurotrophic factor (BDNF) expression after SCI. The rats were divided into five groups: control group, sham operation group, sham operation and exercise group, SCI group, and SCI and exercise group. The laminectomy was performed at the T9–T10 level. The exposed dorsal surface of the spinal cord received contusion injury (10 g × 25 mm) using the impactor. Treadmill exercise was performed 6 days per a week for 6 weeks. In order to evaluate the locomotor function of animals, Basso-Beattie-Bresnahan (BBB) locomotor scale was conducted once a week for 6 weeks. We examined BDNF expression and axonal sprouting in the injury site of the spinal cord using Western blot analysis and immunofluorescence staining. SCI induced loss of locomotor function with decreased BDNF expression in the injury site. Treadmill exercise increased the score of BBB locomotor scale and reduced cavity formation in the injury site. BDNF expression and axonal sprouting within the trabecula were further facilitated by treadmill exercise in SCI-exposed rats. The present study provides the evidence that treadmill exercise may facilitate recovery of locomotor function through axonal regeneration via BDNF expression following SCI. PMID:27656624

  13. Hemisection spinal cord injury in rat: The value of intraoperative somatosensory evoked potential monitoring

    PubMed Central

    Cloud, Beth A.; Ball, Bret G.; Chen, Bingkun; Knight, Andrew M.; Hakim, Jeffrey S.; Ortiz, Ana M.; Windebank, Anthony J.

    2012-01-01

    Techniques used to produce partial spinal cord injuries in animal models have the potential for creating variability in lesions. The amount of tissue affected may influence the functional outcomes assessed in the animals. The recording of somatosensory evoked potentials (SSEPs) may be a valuable tool for assessing the extent of lesion applied in animal models of traumatic spinal cord injury (SCI). Intraoperative tibial SSEP recordings were assessed during surgically induced lateral thoracic hemisection SCI in Sprague-Dawley rats. The transmission of SSEPs, or lack thereof, was determined and compared against the integrity of the dosal funiculi on each side of the spinal cord upon histological sectioning. An association was found between the presence of an SSEP signal and presence of intact dorsal funiculus tissue. The relative risk is 4.50 (95% confidence interval: 1.83 to 11.08) for having an intact dorsal funiculus when the ipsilateral SSEP was present compared to when it was absent. Additionally, the amount of spared spinal cord tissue correlates with final functional assessments at nine weeks post injury: BBB (linear regression, R2 = 0.618, p <0.001) and treadmill test (linear regression, R2 = 0.369, p = 0.016). Therefore, we propose intraoperative SSEP monitoring as a valuable tool to assess extent of lesion and reduce variability between animals in experimental studies of SCI. PMID:22960163

  14. Spinal TRPA1 ion channels contribute to cutaneous neurogenic inflammation in the rat.

    PubMed

    Wei, Hong; Koivisto, Ari; Pertovaara, Antti

    2010-08-02

    In the spinal dorsal horn, TRPA1 ion channels on central terminals of peptidergic primary afferent nerve fibers regulate transmission to glutamatergic and GABAergic interneurons. Here we determine the cutaneous anti-inflammatory effect of a spinally administered TRPA1 channel antagonist to test the hypothesis that spinal TRPA1 channels contribute to cutaneous neurogenic inflammation induced by sustained noxious stimulation. According to the hypothesis, spinal TRPA1 channels facilitate transmission of injury discharge to GABAergic interneurons that induce a dorsal root reflex, which results in increased release of proinflammatory compounds in the skin. Intraplantar capsaicin, a TRPV1 channel agonist, was used to induce neurogenic inflammation in anesthetized rats that were pretreated intrathecally (i.t.), intraplantarly (i.pl.) or intraperitoneally (i.p.) with vehicle or Chembridge-5861526 (CHEM, a TRPA1 channel antagonist). For assessment of neurogenic inflammation, the capsaicin-induced increase of cutaneous blood flow was determined adjacent to the capsaicin-treated skin site with a laser Doppler flowmeter. Capsaicin-induced a marked increase in cutaneous blood flow. The capsaicin-induced blood flow increase was attenuated in a dose-related fashion by i.t. pretreatment with CHEM (3-10microg). Pretreatment with CHEM at a dose of 3mg/kg i.p. or 20microg i.pl. failed to attenuate the capsaicin-induced increase of blood flow. The results indicate that spinal TRPA1 channels contribute to cutaneous neurogenic inflammation adjacent to the injury site, probably by facilitating a dorsal root reflex in peptidergic primary afferent nerve fibers.

  15. Morphology of inhibitory and excitatory interneurons in superficial laminae of the rat dorsal horn.

    PubMed

    Maxwell, David J; Belle, Mino D; Cheunsuang, Ornsiri; Stewart, Anika; Morris, Richard

    2007-10-15

    If we are to stand any chance of understanding the circuitry of the superficial dorsal horn, it is imperative that we can identify which classes of interneuron are excitatory and which are inhibitory. Our aim was to test the hypothesis that there is a correlation between the morphology of an interneuron and its postsynaptic action. We used in vitro slice preparations of the rat spinal cord to characterize and label interneurons in laminae I-III with Neurobiotin. Labelled cells (n = 19) were reconstructed in 3D with Neurolucida and classified according to the scheme proposed by Grudt & Perl (2002). We determined if cells were inhibitory or excitatory by reacting their axon terminals with antibodies to reveal glutamate decrboxylase (for GABAergic cells) or the vesicular glutamate transporter 2 (for glutamatergic cells). All five islet cells retrieved were inhibitory. Of the six vertical (stalked) cells analysed, four were excitatory and, surprisingly, two were inhibitory. It was noted that these inhibitory cells had axonal projections confined to lamina II whereas excitatory vertical cells projected to lamina I and II. Of the remaining neurons, three were radial cells (2 inhibitory, 1 excitatory), two were antennae cells (1 inhibitory, 1 excitatory), one was an inhibitory central cell and the remaining two were unclassifiable excitatory cells. Our hypothesis appears to be correct only for islet cells. Other classes of cells have mixed actions, and in the case of vertical cells, the axonal projection appears to be a more important determinant of postsynaptic action.

  16. 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

  17. 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

  18. An In Vitro Spinal Cord–Hindlimb Preparation for Studying Behaviorally Relevant Rat Locomotor Function

    PubMed Central

    Hayes, Heather Brant; Chang, Young-Hui; Hochman, Shawn

    2009-01-01

    Although the spinal cord contains the pattern-generating circuitry for producing locomotion, sensory feedback reinforces and refines the spatiotemporal features of motor output to match environmental demands. In vitro preparations, such as the isolated rodent spinal cord, offer many advantages for investigating locomotor circuitry, but they lack the natural afferent feedback provided by ongoing locomotor movements. We developed a novel preparation consisting of an isolated in vitro neonatal rat spinal cord oriented dorsal-up with intact hindlimbs free to step on a custom-built treadmill. This preparation combines the neural accessibility of in vitro preparations with the modulatory influence of sensory feedback from physiological hindlimb movement. Locomotion induced by N-methyl d-aspartate and serotonin showed kinematics similar to that of normal adult rat locomotion. Changing orientation and ground interaction (dorsal-up locomotion vs ventral-up air-stepping) resulted in significant kinematic and electromyographic changes that were comparable to those reported under similar mechanical conditions in vivo. We then used two mechanosensory perturbations to demonstrate the influence of sensory feedback on in vitro motor output patterns. First, swing assistive forces induced more regular, robust muscle activation patterns. Second, altering treadmill speed induced corresponding changes in stride frequency, confirming that changes in sensory feedback can alter stride timing in vitro. In summary, intact hindlimbs in vitro can generate behaviorally appropriate locomotor kinematics and responses to sensory perturbations. Future studies combining the neural and chemical accessibility of the in vitro spinal cord with the influence of behaviorally appropriate hindlimb movements will provide further insight into the operation of spinal motor pattern-generating circuits. PMID:19073815

  19. Parcellation of cerebellins 1, 2, and 4 among different subpopulations of dorsal horn neurons in mouse spinal cord.

    PubMed

    Cagle, Michael C; Honig, Marcia G

    2014-02-01

    The cerebellins (Cblns) are a family of secreted proteins that are widely expressed throughout the nervous system, but whose functions have been studied only in the cerebellum and striatum. Two members of the family, Cbln1 and Cbln2, bind to neurexins on presynaptic terminals and to GluRδs postsynaptically, forming trans-synaptic triads that promote synapse formation. Cbln1 has a higher binding affinity for GluRδs and exhibits greater synaptogenic activity than Cbln2. In contrast, Cbln4 does not form such triads and its function is unknown. The different properties of the three Cblns suggest that each plays a distinct role in synapse formation. To begin to elucidate Cbln function in other neuronal systems, we used in situ hybridization to examine Cbln expression in the mouse spinal cord. We find that neurons expressing Cblns 1, 2, and 4 tend to occupy different laminar positions within the dorsal spinal cord, and that Cbln expression is limited almost exclusively to excitatory neurons. Combined in situ hybridization and immunofluorescent staining shows that Cblns 1, 2, and 4 are expressed by largely distinct neuronal subpopulations, defined in part by sensory input, although there is some overlap and some individual neurons coexpress two Cblns. Our results suggest that differences in connectivity between subpopulations of dorsal spinal cord neurons may be influenced by which Cbln each subpopulation contains. Competitive interactions between axon terminals may determine the number of synapses each forms in any given region, and thereby contribute to the development of precise patterns of connectivity in the dorsal gray matter.

  20. Psychological predictors of the effectiveness of radiofrequency lesioning of the cervical spinal dorsal ganglion (RF-DRG).

    PubMed

    Samwel, H; Slappendel, R; Crul, B J; Voerman, V F

    2000-01-01

    In this study, 54 patients suffering from chronic cervicobrachialgia (mean pain duration 7 years) were treated with radiofrequency lesioning of the cervical spinal dorsal root ganglion (RF-DRG). The aim of the study was to investigate whether psychological variables would be predictive for the changes in pain intensity after medical treatment. The following psychological aspects were measured: pain cognitions, negative self-efficacy and catastrophizing, physical and psychosocial dysfunction, and overall distress. The level of catastrophizing before treatment appeared to predict 10% of the changes in pain intensity after treatment. Changes in pain intensity after RF-DRG were positively correlated with changes in psychosocial dysfunction and negative self-efficacy.

  1. Neuropathic Pain Post Spinal Cord Injury Part 2: Systematic Review of Dorsal Root Entry Zone Procedure

    PubMed Central

    2013-01-01

    Background: Pharmacotherapy may not sufficiently reduce neuropathic pain in many individuals post spinal cord injury (SCI). The use of alternative therapies such as surgery may be effective in reducing neuropathic pain in these individuals. However, because of the invasive nature of surgery, it is important to examine the evidence for use of this treatment. Objective: The purpose of this study was to conduct a systematic review of published literature on the surgical treatment of neuropathic pain after SCI. Methods: MEDLINE, CINAHL, EMBASE, and PsycINFO databases were searched for articles in which surgical treatment of pain after SCI was examined. Articles were restricted to the English language. Article selection was conducted by 2 independent reviewers with the following inclusion criteria: the subjects participated in a surgical intervention for neuropathic pain; at least 50% of the subjects had an SCI; at least 3 subjects had an SCI; and a definable intervention involving the dorsal root entry zone (DREZ) procedure was used to reduce pain. Data extracted included study design, study type, subject demographics, inclusion and exclusion criteria, sample size, outcome measures, and study results. Randomized controlled trials (RCTs) were assessed for quality using the Physiotherapy Evidence Database (PEDro) assessment scale. Levels of evidence were assigned to each intervention using a modified Sackett scale. Results: Eleven studies met the inclusion criteria. One study provided level 2 evidence, and the rest provided level 4 evidence. The DREZ procedure was shown to be more effective for segmental pain than for diffuse pain after SCI. Further, individuals with conus medullaris level injury were found to have a higher level of neuropathic pain relief than those with cervical, thoracic, or cauda equina injury. Conclusions: The studies demonstrated that the DREZ procedure may be effective in reducing segmental pain. Hence, DREZ may be important in treatment of

  2. [The extensiveness and specificity of analgesia of electroacupuncture (EA) at different points on the nociceptive responses of neuron in spinal dorsal horn].

    PubMed

    He, X; Zhu, B; Liu, X; Zhang, S; Xu, W

    1993-01-01

    The experiments were performed in anaesthetized rats. The responses of convergent neurons in spinal dorsal horn to noxious stimuli (10mA, 2ms) given at the hindpaw receptive field were recorded extracellularly by glass microelectrodes. The effects of EA on the nociceptive response were observed. EA was applied on ipsilateral "Zusanli" or "Xiaguan" point with high and low intensity. EA (18V, 100Hz) applied on ipsilateral either "Zusanli" or "Xiaguan" could produce strong inhibition on nociceptive responses of convergent neurones (62.74 +/- 4.94% and 64.24 +/- 7.30%). EA (2V, 100Hz) of "Zusanli" also obviously inhibited the nociceptive responses (52.05 +/- 6.69%). But the same EA of "Xiaguan" lacked this inhibitory effect (9.50 +/- 7.67%). There was statistically significant difference between EA effects of "Zusanli" and "Xiaguan" (P < 0.001) when intensity of EA is lower. These results suggested that analgesia of high intensity EA is extensive, but that of low intensity EA is produced only when the point is in the same or nearby spinal segment with nociceptive field, showing the extensiveness and specificity of EA analgesia of different points.

  3. Dorsal horn cells connected to the lissauer tract and their relation to the dorsal root potential in the rat.

    PubMed

    Lidierth, M; Wall, P D

    1998-08-01

    We have examined the role of dorsal horn cells that respond to Lissauer tract stimulation in regulating primary afferent depolarization (PAD). PAD was monitored by recording the dorsal root potential (DRP) in the roots of the lumbar cord. Recordings were made of the discharges of Lissauer tract-responsive cells, and their discharges were correlated with the DRPs occurring spontaneously and those evoked by stimulation. Electrical microstimulation of the Lissauer tract (<10 microA; 200 micros) was used to activate the tract selectively and evoke a characteristic long-latency DRP. Cells that were excited by Lissauer tract stimulation were found in the superficial laminae of the dorsal horn. They exhibited low rates of ongoing discharge and responded to Lissauer tract stimulation typically with a burst of impulses with a latency to onset of 5.6 +/- 2.7 ms (mean +/- SD) and to termination of 13.6 +/- 4.1 ms (n = 105). Lissauer tract-responsive cells in L5 were shown to receive convergent inputs from cutaneous and muscle afferents as they responded to stimulation of the sural nerve (100%, n = 19) and the nerve to gastrocnemius (95%, n = 19). The latency of the response to sural nerve stimulation was 3.7 +/- 1.5 ms and to gastrocnemius nerve stimulation, 8.3 +/- 3.6 ms. Stimulation through a microelectrode at a depth of 1.5 mm in the sensorimotor cortex (100 microA, 200 micros) evoked a response in 17 of 31 Lissauer tract-responsive cells (55%) with a latency to onset of 21.9 +/- 2.8 ms (n = 17). Stimulation of the sural nerve, nerve to gastrocnemius or sensorimotor cortex was shown to depress the response of Lissauer tract-responsive cells to a subsequent Lissauer tract stimulus. The ongoing discharges of Lissauer tract-responsive cells were correlated to the spontaneous DRP using spike-triggered averaging. Of 123 cells analyzed in this way, 117 (95%) were shown to be correlated to the DRP. In addition, the peaks of spontaneous negative DRPs in spinally transected

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

    PubMed Central

    Buesa, Itsaso; Aira, Zigor

    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

  5. Robust spinal neuroinflammation mediates mechanical allodynia in Walker 256 induced bone cancer rats.

    PubMed

    Mao-Ying, Qi-Liang; Wang, Xiao-Wei; Yang, Chang-Jiang; Li, Xiu; Mi, Wen-Li; Wu, Gen-Cheng; Wang, Yan-Qing

    2012-05-20

    It has been reported that remarkable and sustained activation of astrocytes and/or microglia occurs in cancer induced pain (CIP), which is different from neuropathic and inflammatory pain. The present study was designed to investigate the role of spinal Toll-like receptor 4 (TLR4) induced glial neuroinflammation in cancer induced pain using a modified rat model of bone cancer. The rat model of CIP consisted of unilateral intra-tibial injection with Walker 256 mammary gland carcinoma. Nine days after Walker 256 inoculation, a robust activation of both astrocytes and microglia in bilateral spinal dorsal horn was observed together with significant bilateral mechanical allodynia. This neuroinflammation was characterized by enhanced immunostaining of both glial fibrillary acidic protein (GFAP, astrocyte marker) and OX-42 (microglia marker), and an elevated level of IL-1β, IL-6 and TNF-α mRNA. I.t. administration of fluorocitrate (an inhibitor of glial metabolism, 1 nmol) or minocycline (an inhibitor of microglia, 100 μg) has significant anti-allodynic effects on day 12 after Walker 256 inoculation. Naloxone (a nonstereoselective TLR4 signaling blocker, 60 μg, i.t.) also significantly alleviated mechanical allodynia and simultaneously blocked the increased inflammatory cytokine mRNA. The results suggested that spinal TLR4 might play an important role in the sustained glial activation that critically contributed to the robust and sustained spinal neuroinflammation in CIP. This result could potentially help clinicians and researchers to better understand the mechanism of complicated cancer pain.

  6. Dexmedetomidine blocks thermal hyperalgesia and spinal glial activation in rat model of monoarthritis

    PubMed Central

    Xu, Bo; Zhang, Wei-shi; Yang, Jia-le; Xu, Hua; Deng, Xiao-ming; Zhang, Yu-qiu

    2010-01-01

    Aim: To investigate the effect of systemic administration dexmedetomidine, a selective alpha 2 adrenergic receptor (α2AR) agonist, on thermal hyperalgesia and spinal glial activation evoked by monoarthritis (MA). Methods: MA was induced by an intra-articular injection of complete Freund's adjuvant (CFA). Thermal hyperalgesia was measured by Hargreaves' test. The spinal glial activation status was analyzed by GFAP (an astrocytic marker) and Iba-1 (a microglial marker) immunohistochemistry or immunoblotting. Results: Unilateral intra-articular injection of CFA produced a robust glial activation of astrocytes and microglia in the spinal cord, which was associated with the development and maintenance of thermal hyperalgesia. Intraperitoneal (ip) injection of dexmedetomidine (2.5 and 10 μg/kg) was repeatedly given once daily for 5 days with the first injection 60 min before intra-articular CFA. At the dose of 10 μg/kg, dexmedetomidine significantly attenuated MA-induced ipsilateral hyperalgesia from day 2 to day 5. MA-induced up-regulation of GFAP expression on both sides of the spinal dorsal horn was significantly suppressed by day 5 post-MA following dexmedetomidine application, whereas MA-induced Iba-1 up-regulation was only partially suppressed. Conclusion: Systemic dexmedetomidine inhibits the activation of spinal glia, which is possibly associated with its antihyperalgesia in monoarthritic rats. PMID:20364156

  7. Label-free imaging of rat spinal cords based on multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Liao, Chenxi; Wang, Zhenyu; Zhou, Linquan; Zhu, Xiaoqin; Liu, Wenge; Chen, Jianxin

    2016-10-01

    As an integral part of the central nervous system, the spinal cord is a communication cable between the body and the brain. It mainly contains neurons, glial cells, nerve fibers and fiber tracts. The recent development of the optical imaging technique allows high-resolution imaging of biological tissues with the great potential for non-invasively looking inside the body. In this work, we evaluate the imaging capacity of multiphoton microscopy (MPM) based on second harmonic generation (SHG) and two-photon excited fluorescence (TPEF) for the cells and extracellular matrix in the spinal cord at molecular level. Rat spinal cord tissues were sectioned and imaged by MPM to demonstrate that MPM is able to show the microstructure including white matter, gray matter, ventral horns, dorsal horns, and axons based on the distinct intrinsic sources in each region of spinal cord. In the high-resolution and high-contrast MPM images, the cell profile can be clearly identified as dark shadows caused by nuclei and encircled by cytoplasm. The nerve fibers in white matter region emitted both SHG and TPEF signals. The multiphoton microscopic imaging technique proves to be a fast and effective tool for label-free imaging spinal cord tissues, based on endogenous signals in biological tissue. It has the potential to extend this optical technique to clinical study, where the rapid and damage-free imaging is needed.

  8. SPINAL TRANSLOCATOR PROTEIN (TSPO) MODULATES PAIN BEHAVIOR IN RATS WITH CFA-INDUCED MONOARTHRITIS

    PubMed Central

    Hernstadt, Hayley; Wang, Shuxing; Lim, Grewo; Mao, Jianren

    2009-01-01

    Translocator protein 18kDa (TSPO), previously known as the peripheral benzodiazepine receptor (PBR), is predominantly located in the mitochondrial outer membrane and plays an important role in steroidogenesis, immunomodulation, cell survival and proliferation. Previous studies have shown an increased expression of TSPO centrally in neuropathology, as well as in injured nerves. TSPO has also been implicated in modulation of nociception. In the present study, we examined the hypothesis that TSPO is involved in the initiation and maintenance of inflammatory pain using a rat model of Complete Freund’s Adjuvant (CFA)-induced monoarthritis of the tibio-tarsal joint. Immunohistochemistry was performed using Iba-1 (microglia), NeuN (neurons), anti-Glial Fibrillary Acidic Protein, GFAP (astrocytes) and anti-PBR (TSPO) on day 1, 7 and 14 after CFA-induced arthritis. Rats with CFA-induced monoarthritis showed mechanical allodynia and thermal hyperalgesia on the ipsilateral hindpaw, which correlated with the increased TSPO expression in ipsilateral lamina I-II on all experimental days. Iba-1 expression in the ipsilateral dorsal horn was also increased on Day 7 and 14. Moreover, TSPO was co-localized with Iba-1, GFAP and NeuN within the spinal cord dorsal horn. The TSPO agonist Ro5-4864, given intrathecally, dose-dependently retarded or prevented the development of mechanical allodynia and thermal hyperalgesia in rats with CFA-induced monoarthritis. These findings provide evidence that spinal TSPO is involved in the development and maintenance of inflammatory pain behaviors in rats. Thus, spinal TSPO may present a central target as a complementary therapy to reduce inflammatory pain. PMID:19555675

  9. Effects of lateral funiculus sparing, spinal lesion level, and gender on recovery of bladder voiding reflexes and hematuria in rats.

    PubMed

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

    2015-02-01

    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 females, despite

  10. 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.

  11. Spinal SIRPα1-SHP2 interaction regulates spinal nerve ligation-induced neuropathic pain via PSD-95-dependent NR2B activation in rats.

    PubMed

    Peng, Hsien-Yu; Chen, Gin-Den; Lai, Cheng-Yuang; Hsieh, Ming-Chun; Lin, Tzer-Bin

    2012-05-01

    The fact that neuropathic pain mechanisms are not well understood is a major impediment in the development of effective clinical treatments. We examined whether the interaction between signal regulatory protein alpha 1 (SIRPα1) and Src homology-2 domain-containing protein tyrosine phosphatase 2 (SHP2), and the downstream spinal SHP2/postsynaptic density 95 (PSD-95)/N-methyl-d-aspartate receptor NR2B subunit signaling cascade play a role in neuropathic pain. Following spinal nerve ligation (L5), we assessed tactile allodynia using the von Frey filament test and analyzed dorsal horn samples (L4-5) by Western blotting, reverse transcription polymerase chain reaction, coimmunoprecipitation, and immunofluorescence. Nerve ligation induced allodynia, SIRPα1, SHP2, phosphorylated SHP2 (pSHP2), and phosphorylated NR2B (pNR2B) expression, and SHP2-PSD-95, pSHP2-PSD-95, PSD-95-NR2B, and PSD-95-pNR2B coimmunoprecipitation in the ipsilateral dorsal horn. In allodynic rats, injury-induced SHP2 immunoreactivity was localized in the ipsilateral dorsal horn neurons and coincident with PSD-95 and NR2B immunoreactivity. SIRPα1 silencing using small interfering RNA (siRNA; 1, 3, or 5μg/rat for 7days) prevented injury-induced allodynia and the associated changes in protein expression, phosphorylation, and coimmunoprecipitation. Intrathecal administration of NSC-87877 (an SHP2 antagonist; 1, 10, or 100μM/rat) and SIRPα1-neutralizing antibodies (1, 10, or 30μg/rat) suppressed spinal nerve ligation-induced allodynia, spinal SHP2 and NR2B phosphorylation, and SHP2/phosphorylated SHP2-PSD-95 and PSD-95-NR2B/phosphorylated NR2B coprecipitation. SHP2 siRNA led to similar effects as the NSC-87877 and SIRPα1 antibody treatments, except it prevented the allodynia-associated spinal SHP2 expression. In conclusion, our results suggest that a spinal SIRPα1-SHP2 interaction exists that subsequently triggers SHP2/PSD-95/NR2B signaling, thereby playing a role in neuropathic pain development.

  12. Up-Regulation of Pain Behavior and Glial Activity in the Spinal Cord after Compression and Application of Nucleus Pulposus onto the Sciatic Nerve in Rats

    PubMed Central

    Norimoto, Masaki; Sakuma, Yoshihiro; Suzuki, Miyako; Orita, Sumihisa; Yamauchi, Kazuyo; Inoue, Gen; Aoki, Yasuchika; Ishikawa, Tetsuhiro; Miyagi, Masayuki; Kamoda, Hiroto; Kubota, Gou; Oikawa, Yasuhiro; Inage, Kazuhide; Sainoh, Takeshi; Sato, Jun; Nakamura, Junichi; Toyone, Tomoaki; Takahashi, Kazuhisa

    2014-01-01

    Study Design Experimental animal study. Purpose To evaluate pain-related behavior and changes in glial activity in the spinal dorsal horn after combined sciatic nerve compression and nucleus pulposus (NP) application in rats. Overview of Literature Mechanical compression and inflammation caused by prostaglandins and cytokines at disc herniation sites induce pain. Structural changes and pain-associated cytokines in the dorsal root ganglia and spinal dorsal horn contribute to prolonged pain. Glial cells in the spinal dorsal horn may also function in pain transmission. Methods The sciatic nerve was compressed with NP for 2 seconds using forceps in the NP+nerve compression group; the sham-operated group received neither compression nor NP; and the control group received no operation. Mechanical hyperalgesia was measured for 3 weeks using von Frey filaments. Glial activity in the spinal dorsal horn was examined 7 days and 14 days postsurgery using anti-glial fibrillary acidic protein and anti-Ionized calcium binding adaptor molecule-1 antibodies to detect astrocytes and microglia, respectively. Results Mechanical hyperalgesia was detected throughout the 14-day observation in the NP+nerve compression group, but not in control or sham-operated groups (p<0.05). Both astrocytes and microglia were significantly increased in the spinal dorsal horn of the NP+nerve compression group compared to control and sham groups on days 7 and 14 (p<0.05). Conclusions Nerve compression with NP application produces pain-related behavior, and up-regulates astrocytes and microglia in the spinal dorsal horn, suggesting that these glia may be related to pain transmission. PMID:25346806

  13. 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.

  14. Characterization of spinal afferent neurons projecting to different chambers of the rat heart.

    PubMed

    Guić, Maja Marinović; Kosta, Vana; Aljinović, Jure; Sapunar, Damir; Grković, Ivica

    2010-01-29

    The pattern of distribution of spinal afferent neurons (among dorsal root ganglia-DRGs) that project to anatomically and functionally different chambers of the rat heart, as well as their morphological and neurochemical characteristics were investigated. Retrograde tracing using a patch loaded with Fast blue (FB) was applied to all four chambers of the rat heart and labeled cardiac spinal afferents were characterized by using three neurochemical markers. The majority of cardiac projecting neurons were found from T1 to T4 DRGs, whereas the peak was at T2 DRG. There was no difference in the total number of FB-labeled neurons located in ipsilateral and contralateral DRGs regardless of the chambers marked with the patch. However, significantly more FB-labeled neurons projected to the ventricles compared to the atria (859 vs. 715). The proportion of isolectin B(4) binding in FB-labeled neurons was equal among all neurons projecting to different heart chambers (2.4%). Neurofilament 200 positivity was found in greater proportions in DRG neurons projecting to the left side of the heart, whereas calretinin-immunoreactivity was mostly represented in neurons projecting to the left atrium. Spinal afferent neurons projecting to different chambers of the rat heart exhibit a variety of neurochemical phenotypes depending on binding capacity for isolectin B(4) and immunoreactivity for neurofilament 200 and calretinin, and thus represent important baseline data for future studies.

  15. Two-photon laser-scanning microscopy for single and repetitive imaging of dorsal and lateral spinal white matter in vivo.

    PubMed

    Nadrigny, F; Le Meur, K; Steffens, H; Schomburg, E D; Safavi-Abbasi, S; Dibaj, P

    2017-02-28

    We developed appropriate surgical procedures for single and repetitive multi-photon imaging of spinal cord in vivo. By intravenous anesthesia, artificial ventilation and laminectomy, acute experiments were performed in the dorsal and lateral white matter. By volatile anesthesia and minimal-invasive surgery, chronic repetitive imaging up to 8 months were performed in the dorsal column through the window between two adjacent spines. Transgenic mouse technology enabled simultaneous imaging of labeled axons, astrocytes and microglia. Repetitive imaging showed positional shifts of microglia over time. These techniques serve for investigations of cellular dynamics and cell-cell interactions in intact and pathologically changed spinal tissue.

  16. Functional changes in deep dorsal horn interneurons following spinal cord injury are enhanced with different durations of exercise training

    PubMed Central

    Rank, M M; Flynn, J R; Battistuzzo, C R; Galea, M P; Callister, R; Callister, R J

    2015-01-01

    Following incomplete spinal cord injury (SCI), collaterals sprout from intact and injured axons in the vicinity of the lesion. These sprouts are thought to form new synaptic contacts that effectively bypass the lesion epicentre and contribute to improved functional recovery. Such anatomical changes are known to be enhanced by exercise training; however, the mechanisms underlying exercise-mediated plasticity are poorly understood. Specifically, we do not know how SCI alone or SCI combined with exercise alters the intrinsic and synaptic properties of interneurons in the vicinity of a SCI. Here we use a hemisection model of incomplete SCI in adult mice and whole-cell patch-clamp recording in a horizontal spinal cord slice preparation to examine the functional properties of deep dorsal horn (DDH) interneurons located in the vicinity of a SCI following 3 or 6 weeks of treadmill exercise training. We examined the functional properties of local and descending excitatory synaptic connections by recording spontaneous excitatory postsynaptic currents (sEPSCs) and responses to dorsal column stimulation, respectively. We find that SCI in untrained animals exerts powerful effects on intrinsic, and especially, synaptic properties of DDH interneurons. Plasticity in intrinsic properties was most prominent at 3 weeks post SCI, whereas synaptic plasticity was greatest at 6 weeks post injury. Exercise training did not markedly affect intrinsic membrane properties; however, local and descending excitatory synaptic drive were enhanced by 3 and 6 weeks of training. These results suggest exercise promotes synaptic plasticity in spinal cord interneurons that are ideally placed to form new intraspinal circuits after SCI. PMID:25556804

  17. Hydraulic Extrusion of the Spinal Cord and Isolation of Dorsal Root Ganglia in Rodents

    PubMed Central

    Richner, Mette; Jager, Sara B.; Siupka, Piotr; Vaegter, Christian B.

    2017-01-01

    Traditionally, the spinal cord is isolated by laminectomy, i.e. by breaking open the spinal vertebrae one at a time. This is both time consuming and may result in damage to the spinal cord caused by the dissection process. Here, we show how the spinal cord can be extruded using hydraulic pressure. Handling time is significantly reduced to only a few minutes, likely decreasing protein damage. The low risk of damage to the spinal cord tissue improves subsequent immunohistochemical analysis. By performing hydraulic spinal cord extrusion instead of traditional laminectomy, the rodents can further be used for DRG isolation, thereby lowering the number of animals and allowing analysis across tissues from the same rodent. We demonstrate a consistent method to identify and isolate the DRGs according to their localization relative to the costae. It is, however, important to adjust this method to the particular animal used, as the number of spinal cord segments, both thoracic and lumbar, may vary according to animal type and strain. In addition, we illustrate further processing examples of the isolated tissues. PMID:28190031

  18. 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

  19. 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.

  20. Inflammation and hyperalgesia in rats neonatally treated with capsaicin: effects on two classes of nociceptive neurons in the superficial dorsal horn.

    PubMed

    Ren, K; Williams, G M; Ruda, M A; Dubner, R

    1994-11-01

    To address the mechanisms of hyperalgesia and dorsal horn plasticity following peripheral tissue inflammation, the effects of adjuvant-induced inflammation of the rat hindpaw on behavioral nociception and nociceptive neuronal activity in the superficial dorsal horn were examined in neonatally capsaicin-treated rats 6-8 weeks of age. Capsaicin treatment resulted in an 82% loss of unmyelinated fibers in L5 dorsal roots, a dramatic reduction of substance P-like immunoreactivity in the spinal cord, and a significant decrease in the percentage of dorsal horn nociceptive neurons that responded to C-fiber stimulation and noxious heating of the skin. The thermal nociceptive threshold was significantly increased in capsaicin-treated rats, but behavioral hyperalgesia to thermal stimuli still developed in response to inflammation. Following inflammation, there was a significant decrease in mechanical threshold and an increase in response duration to mechanical stimuli in both vehicle- and capsaicin-treated rats, suggesting that a state of mechanical hyperalgesia was also induced. The capsaicin treatment appears to have differential effects on nociceptive specific (NS) and wide-dynamic-range (WDR) neurons in inflamed rats. Expansion of the receptive fields of nociceptive neurons, a measure of the effect of inflammation-induced CNS plasticity, was less extensive for NS than for WDR neurons in capsaicin-treated rats. Compared to vehicle-treated rats, a smaller population of NS neurons, but a similar percentage of WDR neurons, had background activity in inflamed capsaicin-treated rats. C-fiber strength electrical stimulation of the sciatic nerve produced expansion of the receptive fields in a greater portion of NS neurons (53%, P < 0.05) in capsaicin- than in vehicle-treated rats (32%). There was no difference in stimulation-induced expansion of the receptive fields for WDR neurons between vehicle- or capsaicin-treated rats. An N-methyl-D-aspartate receptor antagonist, MK-801

  1. Relationship between mechano-receptive fields of dorsal horn convergent neurons and the response to noxious immersion of the ipsilateral hindpaw in rats.

    PubMed

    McGaraughty, S; Henry, J L

    1997-04-01

    This study examines the relationship between mechano-receptive fields (inhibitory and excitatory, located on the ipsilateral hindpaw) of convergent dorsal horn neurons, and the responses of the neurons to noxious immersion of an entire paw in noxious hot water. In pentobarbital anesthetized rats with intact spinal cords and in unanesthetized decerebrate-spinalized rats, rat hindpaws were immersed in 50 degrees C water for 10 s after the mechano-receptive fields had been delineated using 5-s noxious pinches. Convergent neurons were either excited or inhibited by noxious immersion of the hindpaw. In both groups, a significant association (chi2, P < 0.01) was found between the make-up of the mechano-receptive field and the response of the neuron to immersion. Immersion-inhibited neurons (intact = 27, spinalized = 13), always had both an excitatory and an inhibitory mechano-receptive field on the same hindpaw. Additionally, when the hindpaw was removed from the noxious water, these immersion-inhibited cells displayed a strong afterdischarge which was immediately inhibited once the paw was reimmersed. Pinch-induced and immersion-induced inhibition were found in both spinalized and intact rats suggesting spinal mechanisms were sufficient to mediate this effect. The majority of immersion-excited cells showed only an excitatory mechano-receptive field on the hindpaw (intact rats = 18/23 or 78.3%, spinalized rats = 24/36 or 66.7%). However, other immersion-excited cells had both an inhibitory and an excitatory mechano-receptive field on the hindpaw (intact rats = 5/23 or 21.7%, spinalized rats = 12/36 or 33.3%). The response of a convergent neuron, which has its excitatory receptive field located on a paw, to noxious immersion of the entire paw can be predicted by the make-up of the mechano-receptive fields. Additionally, since noxious paw immersion affects ipsilateral convergent neurons in two opposite manners, it suggests that other effects, such as heterotopic actions

  2. Expression of the immunoglobulin superfamily cell adhesion molecules in the developing spinal cord and dorsal root ganglion.

    PubMed

    Gu, Zirong; Imai, Fumiyasu; Kim, In Jung; Fujita, Hiroko; Katayama, Kei ichi; Mori, Kensaku; Yoshihara, Yoshihiro; Yoshida, Yutaka

    2015-01-01

    Cell adhesion molecules belonging to the immunoglobulin superfamily (IgSF) control synaptic specificity through hetero- or homophilic interactions in different regions of the nervous system. In the developing spinal cord, monosynaptic connections of exquisite specificity form between proprioceptive sensory neurons and motor neurons, however, it is not known whether IgSF molecules participate in regulating this process. To determine whether IgSF molecules influence the establishment of synaptic specificity in sensory-motor circuits, we examined the expression of 157 IgSF genes in the developing dorsal root ganglion (DRG) and spinal cord by in situ hybridization assays. We find that many IgSF genes are expressed by sensory and motor neurons in the mouse developing DRG and spinal cord. For instance, Alcam, Mcam, and Ocam are expressed by a subset of motor neurons in the ventral spinal cord. Further analyses show that Ocam is expressed by obturator but not quadriceps motor neurons, suggesting that Ocam may regulate sensory-motor specificity in these sensory-motor reflex arcs. Electrophysiological analysis shows no obvious defects in synaptic specificity of monosynaptic sensory-motor connections involving obturator and quadriceps motor neurons in Ocam mutant mice. Since a subset of Ocam+ motor neurons also express Alcam, Alcam or other functionally redundant IgSF molecules may compensate for Ocam in controlling sensory-motor specificity. Taken together, these results reveal that IgSF molecules are broadly expressed by sensory and motor neurons during development, and that Ocam and other IgSF molecules may have redundant functions in controlling the specificity of sensory-motor circuits.

  3. 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

  4. The development of catecholaminergic nerves in the spinal cord of rat. II. Regional development.

    PubMed

    Commissiong, J W

    1983-12-01

    The development of noradrenergic and dopaminergic nerves in 5 regions of the developing spinal cord of rat, from fetal day (FD) 16, to the young adult stage was studied. The normal synthetic capacity of adrenergic nerves in the ventral horn of the cervical and lumbar regions developed at the same time, and at the same rate, despite their spatial separation, and before similar development of the noradrenergic nerves in the dorsal horn and zona intermedia. In the ventral horn, the synthesis of NE from injected L-DOPA, as well as the release and metabolism of NE are well-established at 12 h (ND 0.5) after birth. In the dorsal horn these developments occur later at ND 4. Except in the dorsal horn of the cervical region, there was no easily observable, consistent pattern in the development of regional spinal dopaminergic innervation. The capacity of the developing cord to synthesize dopamine (DA) from injected DOPA is significantly developed at FD 16 (the earliest time studied), and peaked in all regions as early as ND 4. Control experiments indicate that 100%, and only 10% respectively of NE and DA synthetized from injected DOPA, occurred in descending monoaminergic fibers. Norepinephrine is synthesized exclusively in noradrenergic nerves. Cells appear transiently in the developing cord at FD 18, that are capable of synthesizing catecholamines (probably mainly DA) from injected DOPA. During postnatal development of the cord, and to a less extent in the adult, the network of catecholaminergic nerves actually present, is more extensive than that normally revealed during routine fluorescence microscopy. The results are discussed in the context of current attempts to understand the functional importance of catecholaminergic nerves in the mammalian spinal cord, and elsewhere in the CNS.

  5. Overexpression of suppressor of cytokine signaling 3 in dorsal root ganglion attenuates cancer-induced pain in rats

    PubMed Central

    Wei, Jinrong; Li, Meng; Wang, Dieyu; Zhu, Hongyan; Kong, Xiangpeng; Wang, Shusheng; Zhou, You-Lang; Ju, Zhong; Jiang, Guo-Qin

    2017-01-01

    Background Cancer-induced pain (CIP) is one of the most severe types of chronic pain with which clinical treatment remains challenging and the involved mechanisms are largely unknown. Suppressor of cytokine signaling 3 (SOCS3) is an important intracellular protein and provides a classical negative feedback loop, thus involving in a wide variety of processes including inflammation and nociception. However, the role of SOCS3 pathway in CIP is poorly understood. The present study was designed to investigate the role of SOCS3 in dorsal root ganglion (DRG) in the development of CIP. Method CIP was established by injection of Walker 256 mammary gland tumor cells into the rat tibia canal. Whole-cell patch clamping and Western blotting were performed. Results Following the development of bone cancer, SOCS3 expression was significantly downregulated in rat DRGs at L2–L5 segments. Overexpression of SOCS3, using lentiviral-mediated production of SOCS3 at spinal cord level, drastically attenuated mechanical allodynia and body weight-bearing difference, but not thermal hyperalgesia in bone cancer rats. In addition, overexpression of SOCS3 reversed the hyperexcitability of DRG neurons innervating the tibia, and reduced abnormal expression of toll-like receptors 4 in the DRGs. Conclusions These results suggest that SOCS3 might be a key molecular involved in the development of complicated cancer pain and that overexpression of SOCS3 might be an important strategy for treatment for mechanical allodynia associated with bone cancer. PMID:28326931

  6. Effects of spinal and peripheral nerve lesions on the intersegmental synchronization of the spontaneous activity of dorsal horn neurons in the cat lumbosacral spinal cord.

    PubMed

    García, C A; Chávez, D; Jiménez, I; Rudomin, P

    2004-05-06

    In the anesthetized and paralyzed cat, spontaneous negative cord dorsum potentials (nCDPs) appeared synchronously in the L3 to S1 segments, both ipsi- and contralaterally. The acute section of both the intact sural and the superficial peroneal nerve increased the variability of the spontaneous nCDPs without affecting their intersegmental coupling. On the other hand, the synchronization between the spontaneous nCDPs recorded in segments L5-L6 was strongly reduced following an interposed lesion of the left (ipsilateral) dorsolateral spinal quadrant and it was almost completely abolished by an additional lesion of the contralateral dorsolateral quadrant at the same level. Our observations support the existence of a system of spontaneously active dorsal horn neurons that is bilaterally distributed along the lumbosacral segments and affects, in a synchronized and organized manner, impulse transmission along many reflex pathways, including those mediating presynaptic inhibition.

  7. Direct sensorimotor corticospinal modulation of dorsal horn neuronal C-fiber responses in the rat.

    PubMed

    Rojas-Piloni, Gerardo; Martínez-Lorenzana, Guadalupe; Condés-Lara, Miguel; Rodríguez-Jiménez, Javier

    2010-09-10

    Clinically, the stimulation of motor cortical areas has been used to alleviate certain pain conditions. However, the attempts to understand the mechanisms of cortical nociceptive modulation at the spinal cord level have yielded controversial results. The objectives of the present work were to: 1) determine the effects of activating and suppressing the activity of sensorimotor cortical neurons on the nociceptive electrophysiological responses of the segmental C-fibers, and 2) evaluate the contribution of direct and indirect corticospinal projections in segmental nociceptive modulation. By means of a bipolar matrix of stimulation electrodes we mapped the stimulation of cortical areas that modulate C-fiber evoked field potentials in the dorsal horn. In addition, suppressing the cortical activity by means of cortical spreading depression, we observed that the C-fiber evoked field potentials in the dorsal horn are facilitated when cortical activity is suppressed specifically in sensorimotor cortex. Moreover, the C-fiber evoked field potentials were inhibited during spontaneous activation of cortical projecting neurons. Furthermore, after a lesion of the pyramidal tract contralateral to the spinal cord recording sites, the cortical action was suppressed. Our results show that corticospinal tract fibers arising from the sensorimotor cortex modulate directly the nociceptive C-fiber evoked responses of the dorsal horn.

  8. 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

  9. Distribution of purinergic P2X receptors in the equine digit, cervical spinal cord and dorsal root ganglia.

    PubMed

    Zamboulis, D E; Senior, J M; Clegg, P D; Gallagher, J A; Carter, S D; Milner, P I

    2013-09-01

    Purinergic pathways are considered important in pain transmission, and P2X receptors are a key part of this system which has received little attention in the horse. The aim of this study was to identify and characterise the distribution of P2X receptor subtypes in the equine digit and associated vasculature and nervous tissue, including peripheral nerves, dorsal root ganglia and cervical spinal cord, using PCR, Western blot analysis and immunohistochemistry. mRNA signal for most of the tested P2X receptor subunits (P2X1-5, 7) was detected in all sampled equine tissues, whereas P2X6 receptor subunit was predominantly expressed in the dorsal root ganglia and spinal cord. Western blot analysis validated the specificity of P2X1-3, 7 antibodies, and these were used in immunohistochemistry studies. P2X1-3, 7 receptor subunits were found in smooth muscle cells in the palmar digital artery and vein with the exception of the P2X3 subunit that was present only in the vein. However, endothelial cells in the palmar digital artery and vein were positive only for P2X2 and P2X3 receptor subunits. Neurons and nerve fibres in the peripheral and central nervous system were positive for P2X1-3 receptor subunits, whereas glial cells were positive for P2X7 and P2X1 and 2 receptor subunits. This previously unreported distribution of P2X subtypes may suggest important tissue specific roles in physiological and pathological processes.

  10. 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.

  11. Idiopathic spinal cord herniation with duplicated dura mater and dorsal subarachnoid septum. Report of a case and review of the literature

    PubMed Central

    Yamamoto, Norio; Higashino, Kousaku; Sairyo, Koichi

    2014-01-01

    Background Idiopathic spinal cord herniation (ISCH) is a rare condition and its pathogenesis remains unclear. The purpose of this case report is to present an ISCH case with dorsal subarachnoid septum suggesting the pathogenesis of ISCH being adhesions from preexisting inflammation. Methods Single case report. Results A 60-year-old woman presented with Brown-Séquard syndrome below the level of T6. Magnetic resonance imaging revealed the thoracic spinal cord was displaced ventrally, and the dorsal subarachnoid space was enlarged and had a septum between the spinal cord and dura mater. Intraoperatively, the dorsal dura mater was seen to be adherent and the subarachnoid septum was identified after durotomy. The inner layer defect of the duplicated dura mater was found in the ventral dura mater, through which the spinal cord had herniated. After releasing the septum, the adhesions around the dura mater, and the hiatus, the spinal cord was reduced. Conclusions The present case indicates that adhesions around the dura mater can be the pathogenesis of ISCH. PMID:25694934

  12. Genetic deletion of synapsin II reduces neuropathic pain due to reduced glutamate but increased GABA in the spinal cord dorsal horn.

    PubMed

    Schmidtko, Achim; Luo, Ceng; Gao, Wei; Geisslinger, Gerd; Kuner, Rohini; Tegeder, Irmgard

    2008-10-31

    The synaptic vesicle protein synapsin II is specifically expressed in synaptic terminals of primary afferent nociceptive neurons and regulates transmitter release in the spinal cord dorsal horn. Here, we assessed its role in nerve injury-evoked molecular and behavioral adaptations in models of peripheral neuropathic pain using mice genetically lacking synapsin II. Deficiency of synapsin II resulted in reduced mechanical and cold allodynia in two models of peripheral neuropathic pain. This was associated with decreased glutamate release in the dorsal horn of the spinal cord upon sciatic nerve injury or capsaicin application onto the sciatic nerve and reduced calcium signals in spinal cord slices upon persistent activation of primary afferents. In addition, the expression of the vesicular glutamate transporters, VGLUT1 and VGLUT2, was strongly reduced in synapsin II knockout mice in the spinal cord. Conversely, synapsin II knockout mice showed a stronger and longer-lasting increase of GABA in lamina II of the dorsal horn after nerve injury than wild type mice. These results suggest that synapsin II is involved in the regulation of glutamate and GABA release in the spinal cord after nerve injury, and that a imbalance between glutamatergic and GABAergic synaptic transmission contributes to the manifestation of neuropathic pain.

  13. 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.

  14. [Calcium current and GABA(B) receptors in dorsal sensory cells of the lamprey spinal cord].

    PubMed

    Batueva, I V; Buchanan, J T; Tsvetkov, E A; Sagatelian, A K; Veselkin, N P

    1997-01-01

    GABA and GABAB receptor agonists were shown to reduce the peak calcium current amplitude with its subsequent recovery, whereas glycine and taurine, the GABAA receptor agonists, did not modify the current. The findings suggest that the GABAB receptors mediate a presynaptic inhibition by suppression of the Calcium currents in the cyclostome spinal cord.

  15. Spinal stimulation of the upper lumbar spinal cord modulates urethral sphincter activity in rats after spinal cord injury.

    PubMed

    Abud, Edsel M; Ichiyama, Ronaldo M; Havton, Leif A; Chang, Huiyi H

    2015-05-01

    After spinal cord injury (SCI), the neurogenic bladder is observed to develop asynchronous bladder and external urethral sphincter (EUS) contractions in a condition known as detrusor-sphincter dyssnergia (DSD). Activation of the EUS spinal controlling center located at the upper lumbar spinal cord may contribute to reduce EUS dyssynergic contractions and decrease urethral resistance during voiding. However, this mechanism has not been well studied. This study aimed at evaluating the effects of epidural stimulation (EpS) over the spinal EUS controlling center (L3) in combination with a serotonergic receptor agonist on EUS relaxation in naive rats and chronic (6-8 wk) T8 SCI rats. Cystometrogram and EUS electromyography (EMG) were obtained before and after the intravenous administration of 5HT-1A receptor agonist and antagonist. The latency, duration, frequency, amplitude, and area under curve of EpS-evoked EUS EMG responses were analyzed. EpS on L3 evoked an inhibition of EUS tonic contraction and an excitation of EUS intermittent bursting/relaxation correlating with urine expulsion in intact rats. Combined with a 5HT-1A receptor agonist, EpS on L3 evoked a similar effect in chronic T8 SCI rats to reduce urethral contraction (resistance). This study examined the effect of facilitating the EUS spinal controlling center to switch between urine storage and voiding phases by using EpS and a serotonergic receptor agonist. This novel approach of applying EpS on the EUS controlling center modulates EUS contraction and relaxation as well as reduces urethral resistance during voiding in chronic SCI rats with DSD.

  16. Comparative analysis of NADPH-diaphorase positive neurons in the rat, rabbit and pheasant thoracic spinal cord. A histochemical study.

    PubMed

    Kluchová, D; Rybárová, S; Miklosová, M; Lovásová, K; Schmidtová, K; Dorko, F

    2001-01-01

    The distribution of NADPH-diaphorase (NADPH-d) activity was investigated and compared in the rat, rabbit and pheasant thoracic spinal cord. The investigation of all spinal cord regions (laminae) in three experimental species revealed marked differences in the distribution of NADPH-d activity. Cross sectional analysis of the spinal cord of the rat, rabbit and pheasant confirmed differences in the shape of the gray matter in all examined species. More detailed investigation of Rexed's laminas showed similar distribution of NADPH-d activity in the spinal cord of the rat and rabbit, which were different when compared with the spinal cord of the pheasant. Ventral horn of the rat and rabbit showed no labelling whereas in pheasant this area possessed a number of scattered, intensively stained neurons. In the location of autonomic preganglionic neurons, differences were found as well. In the rat there was seen a number of densely packed, clearly dark blue coloured neurons. Similarly, these neurons were present in the rabbit spinal cord but they were less numerous. No staining was found in this region of pheasant. Pericentral area (lamina X) and intermediate zone (laminaVII) revealed the presence of NADPH-d positive neurons in all examined species although they differed in number and shape of their bodies. The dorsal horn showed the presence of NADPH-d staining in all three animals but its distribution was different in medio-lateral direction. It can be suggested that observed differencies in the presence and distribution of NADPH-d activity across the examined species may reflect different fylogenetic development.

  17. Role of spinal cholecystokinin in neuropathic pain after spinal cord hemisection in rats.

    PubMed

    Kim, Junesun; Kim, Jung Hoon; Kim, Youngkyung; Cho, Hwi-young; Hong, Seung Kil; Yoon, Young Wook

    2009-10-25

    In the present study we determined whether spinal cholecystokinin (CCK) or the cholecystokinin receptor is involved in below-level neuropathic pain of spinal cord injury (SCI). The effect of the CCK(B) receptor antagonist, CI-988 on mechanical allodynia and the expression level of CCK and CCK(B) receptor were investigated. Spinal hemisection was done at the T13 level in rats under enflurane anesthesia. CI-988 was administered intraperitoneally and intrathecally and behavioral tests were conducted. After systemic injection, mechanical allodynia was reduced by higher doses of CI-988 (10 and 20mg/kg). Intrathecal CI-988 (100, 200 and 500 microg) dose-dependently increased the paw withdrawal threshold in both paws. Following spinal hemisection, CCK mRNA expression increased on the ipsilateral side at the spinal segments caudal to the injury and both sides of the spinal L4-5 segments without any significant changes in CCK(B) receptor mRNA levels. These results suggest that up-regulation of spinal CCK may contribute to maintenance of mechanical allodynia following SCI and that clinical application of CI-988 or similar drugs may be useful therapeutic agents for management of central neuropathic pain.

  18. Spinal astrocytic activation contributes to mechanical allodynia in a rat model of cyclophosphamide-induced cystitis

    PubMed Central

    Liu, Bolong; Su, Minzhi; Tang, ShaoJun; Zhan, Hailun; Yang, Fei; Li, Wenbiao; Li, Tengcheng; Xie, Juncong

    2016-01-01

    Background Previous studies have demonstrated that glial cells play an important role in the generation and maintenance of neuropathic pain. Activated glial cells produce numerous mediators such as proinflammatory cytokines that facilitate neuronal activity and synaptic plasticity. Similarly, bladder pain syndrome/interstitial cystitis shares many characteristics of neuropathic pain. However, related report on the involvement of spinal glia in bladder pain syndrome/interstitial cystitis-associated pathological pain and the underlying mechanisms are still lacking. The present study investigated spinal glial activation and underlying molecular mechanisms in a rat model of bladder pain syndrome/interstitial cystitis. Results A rat model of bladder pain syndrome/interstitial cystitis was established via systemic injection with cyclophosphamide. Mechanical allodynia was tested with von Frey monofilaments and up-down method. Moreover, Western blots and double immunofluorescence were used to detect the expression and location of glial fibrillary acidic protein, OX42/Iba1, P-P38, NeuN, interleukin (IL)-1β, phosphorylation of N-methyl-D-aspartate receptor 1 (P-NR1), and IL-1 receptor I (IL-1RI) in the L6-S1 spinal cord. We found that glial fibrillary acidic protein rather than OX42/Iba1 or P-P38 was significantly increased in the spinal cord of cyclophosphamide-induced cystitis. L-alpha-aminoadipate but not minocycline markedly attenuated the allodynia. Furthermore, we found that spinal IL-1β was dramatically increased in cyclophosphamide-induced cystitis, and activated astrocytes were the only source of IL-1β release, which contributed to allodynia in cystitis rats. Besides, spinal P-NR1 was statistically increased in cyclophosphamide-induced cystitis and only localized in IL-1RI positive neurons in spinal dorsal horn. Additionally, NR antagonist significantly attenuated the cystitis-induced pain. Interestingly, the time course of the P-NR1 expression paralleled to that

  19. Decoding intravesical pressure from local field potentials in rat lumbosacral spinal cord

    NASA Astrophysics Data System (ADS)

    Im, Changkyun; Park, Hae Yong; Koh, Chin Su; Ryu, Sang Baek; Seo, In Seok; Kim, Yong Jung; Kim, Kyung Hwan; Shin, Hyung-Cheul

    2016-10-01

    Chronic monitoring of intravesical pressure is required to detect the onset of intravesical hypertension and the progression of a more severe condition. Recent reports demonstrate the bladder state can be monitored from the spiking activity of the dorsal root ganglia or lumbosacral spinal cord. However, one of the most serious challenges for these methods is the difficulty of sustained spike signal acquisition due to the high-electrode-location-sensitivity of spikes or neuro-degeneration. Alternatively, it has been demonstrated that local field potential recordings are less affected by encapsulation reactions or electrode location changes. Here, we hypothesized that local field potential (LFP) from the lumbosacral dorsal horn may provide information concerning the intravesical pressure. LFP and spike activities were simultaneously recorded from the lumbosacral spinal cord of anesthetized rats during bladder filling. The results show that the LFP activities carry significant information about intravesical pressure along with spiking activities. Importantly, the intravesical pressure is decoded from the power in high-frequency bands (83.9-256 Hz) with a substantial performance similar to that of the spike train decoding. These findings demonstrate that high-frequency LFP activity can be an alternative intravesical pressure monitoring signal, which could lead to a proper closed loop system for urinary control.

  20. Minocycline reduces the injury-induced expression of prodynorphin and pronociceptin in the dorsal root ganglion in a rat model of neuropathic pain.

    PubMed

    Mika, J; Rojewska, E; Makuch, W; Przewlocka, B

    2010-02-17

    A role of neuropeptides in neuropathic pain development has been implicated; however, the neuroimmune interactions that are involved in the underlying mechanisms may be more important than previously thought. To examine a potential role of relations between glia cells and neuropeptides in neuropathic pain, we performed competitive reverse-transcription polymerase chain reaction (RT-PCR) from the dorsal lumbar spinal cord and the dorsal root ganglion (DRG) after chronic constriction injury (CCI) in the rat sciatic nerve. The RT-PCR results indicated that complement component 1, q subcomponent (C1q) mRNA expression was higher than glial fibrillary acidic protein (GFAP) in the spinal cord 3 and 7 days post-CCI, suggesting that spinal microglia and perivascular macrophages are more activated than astrocytes. In parallel, we observed a strong upregulation of prodynorphin mRNA in the spinal cord after CCI, with no changes in the expression of proenkephalin or pronociceptin. Conversely, the expression of GFAP mRNA in the DRG was higher than C1q, which suggests that the satellite cells are activated shortly after injury, followed by the macrophages and polymorphonuclear leukocytes infiltrating the DRG. In the DRG, we also observed a very strong upregulation of prodynorphin (1387%) as well as pronociceptin (122%) and a downregulation of proenkephalin (47%) mRNAs. Interestingly, preemptive and repeated i.p. injection of minocycline reversed the activation of microglia/macrophages in the spinal cord and the trafficking of peripheral immune cells into the DRG, and markedly diminished the upregulation of prodynorphin and pronociceptin in the DRG. We thus provide novel findings that inhibition of C1q-positive cells by minocycline can diminish injury-induced neuropeptide changes in the DRG. This suggests that immune cells-derived pronociceptive factors may influence opioid peptide expression. Therefore, the injury-induced activation of microglia and leukocytes and the subsequent

  1. Serotonin neuronal release from dorsal hippocampus following electrical stimulation of the dorsal and median raphé nuclei in conscious rats.

    PubMed

    Mokler, D J; Lariviere, D; Johnson, D W; Theriault, N L; Bronzino, J D; Dixon, M; Morgane, P J

    1998-01-01

    We have studied 5-hydroxytryptamine (5-HT) release in the hippocampal formation following electrical stimulation of the dorsal and median raphé nuclei in the behaving rat. The primary finding in this study is a decrease in neuronal release of serotonin in the dorsal hippocampal formation following electrical stimulation of either the dorsal or median raphé nucleus in conscious rats. At no time did electrical stimulation of either raphé nucleus result in behavioral, including vigilance state, changes. The amount of 5-HT released was found to be frequency dependent with higher frequencies (20 Hz) producing larger decreases in release of 5-HT. However, the pattern of release differs between the two raphé nuclei. Extracellular levels of 5-HT decrease during stimulation of the dorsal raphé, whereas levels decrease only following cessation of stimulation of the median raphé nucleus. This may relate to the patterns of innervation of the dorsal hippocampal formation by these two midbrain raphé nuclei and also may reflect an inhibition of median raphé cell firing during stimulation of the dorsal raphé. Electrical stimulation of the dorsal raphé in anesthetized animals resulted in an enhanced release of 5-HT. The suppression of 5-HT release in the dorsal hippocampal formation in behaving animals was long-lasting (over 2 h), suggesting that the control mechanisms that regulate 5-HT release operate over a long time-course. This difference in release between non-anesthetized and anesthetized animals may relate to anesthesia blocking long- and/or short-loop serotonin recurrent axonal collaterals negatively feeding back onto 5-HT1A and 5-HT1D somatodendritic autoreceptors on raphé neurons. Further, the anesthetized animal has diminished monoaminergic "gating" influences on the hippocampal formation, whereas the behaving animal is more complex with behavioral (vigilance) states associated with different patterns of gating of information flow through the hippocampal

  2. TRPA1 ion channel in the spinal dorsal horn as a therapeutic target in central pain hypersensitivity and cutaneous neurogenic inflammation.

    PubMed

    Pertovaara, Antti; Koivisto, Ari

    2011-09-01

    Transient receptor potential ankyrin 1 (TRPA1) is a non-selective, calcium permeable cation channel expressed by a subpopulation of primary afferent nociceptive nerve fibers. On peripheral nerve endings, TRPA1 channel contributes to transduction of chemical and physical stimuli, whereas on the central endings in the spinal dorsal horn, which is the topic of this brief review, it regulates glutamatergic transmission. Blockade of the spinal TRPA1 channel has attenuated mechanical pain hypersensitivity particularly to low-intensity stimulation in various pathophysiological conditions, whereas blockade of the TRPA1 channel-mediated regulation of transmission failed to influence baseline pain behavior in healthy control animals. Additionally, blockade of the spinal TRPA1 channel reduced cutaneous neurogenic inflammation, presumably by decreasing drive of spinal interneurons that induce a proinflammatory dorsal root reflex. The spinal TRPA1 channel provides a promising target for development of a selective disease-modifying therapy for central pain hypersensitivity. Blockade of the spinal TRPA1 channel-mediated regulation of transmission may also attenuate cutaneous neurogenic inflammation.

  3. 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

  4. Isoflurane, But Not the Nonimmobilizers F6 and F8, Inhibits Rat Spinal Cord Motor Neuron CaV1 Calcium Currents

    PubMed Central

    Recio-Pinto, Esperanza; Montoya-Gacharna, Jose V.; Xu, Fang; Blanck, Thomas J.J.

    2015-01-01

    Background Volatile anesthetics decrease Ca2+ entry through voltage-dependent Ca2+ channels. Ca2+ influences neurotransmitter release and neuronal excitability. Because volatile anesthetics act specifically on the spinal cord to produce immobility, we examined the effect of isoflurane and the nonimmobilizers F6 (1, 2- dichlorohexafluorocyclobutane) and F8 (2, 3- dichlorooctafluorobutane) on CaV1 and CaV2 Ca2+ channels in spinal cord motor neurons and dorsal root ganglion neurons. Methods Using patch clamping, we compared the effects of isoflurane with those of F6 and F8 on CaV1 and CaV2 channels in isolated, cultured adult rat spinal cord motor neurons and on CaV1 and CaV2 channels in adult rat dorsal root ganglion sensory neurons. Results In spinal cord motor neurons, isoflurane, but not F6 or F8, inhibited currents through CaV1 channels. Isoflurane and at least one of the nonimmobilizers inhibited currents through CaV1 and CaV2 channels in dorsal root ganglion neurons and Cav2 in spinal cord motor neurons Conclusion The findings that isoflurane, but not nonimmobilizers, inhibited CaV1 Ca2+ channels in spinal cord motor neurons are consistent with the notion that spinal cord motor neurons might mediate isoflurane-induced immobility. Additional studies are required to examine whether inhibition of CaV1 calcium currents in spinal cord motor neurons are sufficient, or whether actions on other channels/proteins also contribute to isoflurane-induced immobility. PMID:26702867

  5. Kv3.1b and Kv3.3 channel subunit expression in murine spinal dorsal horn GABAergic interneurones.

    PubMed

    Nowak, A; Mathieson, H R; Chapman, R J; Janzsó, G; Yanagawa, Y; Obata, K; Szabo, G; King, A E

    2011-09-01

    GABAergic interneurones, including those within spinal dorsal horn, contain one of the two isoforms of the synthesizing enzyme glutamate decarboxylase (GAD), either GAD65 or GAD67. The physiological significance of these two GABAergic phenotypes is unknown but a more detailed anatomical and functional characterization may help resolve this issue. In this study, two transgenic Green Fluorescent Protein (GFP) knock-in murine lines, namely GAD65-GFP and GAD67-GFP (Δneo) mice, were used to profile expression of Shaw-related Kv3.1b and Kv3.3 K(+)-channel subunits in dorsal horn interneurones. Neuronal expression of these subunits confers specific biophysical characteristic referred to as 'fast-spiking'. Immuno-labelling for Kv3.1b or Kv3.3 revealed the presence of both of these subunits across the dorsal horn, most abundantly in laminae I-III. Co-localization studies in transgenic mice indicated that Kv3.1b but not Kv3.3 was associated with GAD65-GFP and GAD67-GFP immunopositive neurones. For comparison the distributions of Kv4.2 and Kv4.3 K(+)-channel subunits which are linked to an excitatory neuronal phenotype were characterized. No co-localization was found between GAD-GFP +ve neurones and Kv4.2 or Kv4.3. In functional studies to evaluate whether either GABAergic population is activated by noxious stimulation, hindpaw intradermal injection of capsaicin followed by c-fos quantification in dorsal horn revealed co-expression c-fos and GAD65-GFP (quantified as 20-30% of GFP +ve population). Co-expression was also detected for GAD67-GFP +ve neurones and capsaicin-induced c-fos but at a much reduced level of 4-5%. These data suggest that whilst both GAD65-GFP and GAD67-GFP +ve neurones express Kv3.1b and therefore may share certain biophysical traits, their responses to peripheral noxious stimulation are distinct.

  6. Enlargement of the receptive field size to low intensity mechanical stimulation in the rat spinal nerve ligation model of neuropathy.

    PubMed

    Suzuki, R; Kontinen, V K; Matthews, E; Williams, E; Dickenson, A H

    2000-06-01

    One characteristic of plasticity after peripheral tissue or nerve damage is receptive field reorganization, and enlargement of receptive field size has been suggested to occur in certain models of neuropathic pain. The aim of the present study was to explore whether enlargement of neuronal receptive fields could contribute to the mechanical allodynia found on the ipsilateral paw in the spinal nerve ligation model of neuropathy. After ligation of L(5)-L(6) spinal nerves, all rats developed behavioral signs of mechanical allodynia, while the sham-operated control group displayed no such changes. The characteristics of the evoked responses of the neurones recorded in the dorsal horn of the rats were similar between the spinal nerve ligation, the sham operated control group, and the nonoperated control group, except for spontaneous activity, which was significantly increased in the spinal nerve ligation group. The mean size of the receptive field on the ipsilateral hindpaw, mapped using low-intensity stimulation with 9-g von Frey hair, was significantly increased in the spinal nerve ligation group, as compared to the sham-operated group. No significant difference was seen with 15- or 75-g von Frey hairs. The distribution of the receptive fields over the plantar surface of the paw was similar between the study groups. The enlargement of receptive field for non-noxious touch could be an indication of central sensitization in this model.

  7. 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.

  8. Estrogen status and psychophysical stress modify temporomandibular joint input to medullary dorsal horn neurons in a lamina-specific manner in female rats.

    PubMed

    Okamoto, Keiichiro; Thompson, Randall; Katagiri, Ayano; Bereiter, David A

    2013-07-01

    Estrogen status and psychological stress contribute to the expression of several chronic pain conditions including temporomandibular muscle and joint disorders (TMJD). Sensory neurons that supply the temporomandibular joint (TMJ) region terminate in laminae I and V of the spinal trigeminal nucleus (Vc/C1-2 region); however, little is known about lamina-specificity and environmental influences on the encoding properties of TMJ brainstem neurons. To test the hypothesis that Vc/C1-2 neurons integrate both interoceptive and exteroceptive signals relevant for TMJ nociception, we recorded TMJ-evoked activity in superficial and deep laminae of ovariectomized rats under high and low estradiol (E2) and stress conditions. Rats received daily injections of low (LE) or high (HE) dose E2 and were subjected to forced swim (FS) or sham swim conditioning for 3days. The results revealed marked lamina-specificity in that HE rats displayed enhanced TMJ-evoked activity in superficial, but not deep, laminae independent of stress conditioning. By contrast, FS conditioned rats displayed increased background firing and TMJ-evoked activity of neurons in deep, but not superficial, laminae independent of E2 status. FS also enhanced TMJ-evoked masseter muscle activity and suggested the importance of deep dorsal horn neurons in mediating evoked jaw muscle activity. In conclusion, E2 status and psychophysical stress play a significant role in modifying the encoding properties of TMJ-responsive medullary dorsal horn neurons with a marked lamina-specificity.

  9. Activation of spinal chemokine receptor CXCR3 mediates bone cancer pain through an Akt-ERK crosstalk pathway in rats.

    PubMed

    Guan, Xue-Hai; Fu, Qiao-Chu; Shi, Dai; Bu, Hui-Lian; Song, Zhen-Peng; Xiong, Bing-Rui; Shu, Bin; Xiang, Hong-Bing; Xu, Bing; Manyande, Anne; Cao, Fei; Tian, Yu-Ke

    2015-01-01

    Previously, we showed that activation of the spinal CXCL9, 10/CXCR3 pathway mediated bone cancer pain (BCP) in rats. However, the cellular mechanism involved is poorly understood. Here, we found that the activated CXCR3 was co-localized with either neurons, microglia, and astrocytes in the spinal cord, or non-peptidergic-, peptidergic-, and A-type neurons in the dorsal root ganglion. The inoculation of Walker-256 mammary gland carcinoma cells into the rat's tibia induced a time-dependent phosphorylation of Akt and extracellular signal-regulated kinase (ERK1/2) in the spinal cord, and CXCR3 was necessary for the phosphorylation of Akt and ERK 1/2. Meanwhile, CXCR3 was co-localized with either pAkt or pERK1/2. Blockage of either Akt or ERK1/2 prevented or reversed the mechanical allodynia in BCP rats. Furthermore, there was cross-activation between PI3K/Akt and Raf/MEK/ERK pathway under the BCP condition. Our results demonstrated that the activation of spinal chemokine receptor CXCR3 mediated BCP through Akt and ERK 1/2 kinase, and also indicated a crosstalk between PI3K/Akt and Raf/MEK/ERK signaling pathways under the BCP condition.

  10. Mechanical characterization of the injured spinal cord after lateral spinal hemisection injury in the rat.

    PubMed

    Saxena, Tarun; Gilbert, Jeremy; Stelzner, Dennis; Hasenwinkel, Julie

    2012-06-10

    The glial scar formed at the site of traumatic spinal cord injury (SCI) has been classically hypothesized to be a potent physical and biochemical barrier to nerve regeneration. One longstanding hypothesis is that the scar acts as a physical barrier due to its increased stiffness in comparison to uninjured spinal cord tissue. However, the information regarding the mechanical properties of the glial scar in the current literature is mostly anecdotal and not well quantified. We monitored the mechanical relaxation behavior of injured rat spinal cord tissue at the site of mid-thoracic spinal hemisection 2 weeks and 8 weeks post-injury using a microindentation test method. Elastic moduli were calculated and a modified standard linear model (mSLM) was fit to the data to estimate the relaxation time constant and viscosity. The SLM was modified to account for a spectrum of relaxation times, a phenomenon common to biological tissues, by incorporating a stretched exponential term. Injured tissue exhibited significantly lower stiffness and elastic modulus in comparison to uninjured control tissue, and the results from the model parameters indicated that the relaxation time constant and viscosity of injured tissue were significantly higher than controls. This study presents direct micromechanical measurements of injured spinal cord tissue post-injury. The results of this study show that the injured spinal tissue displays complex viscoelastic behavior, likely indicating changes in tissue permeability and diffusivity.

  11. Autoradiographic localization of [3H]thiocolchicoside binding sites in the rat brain and spinal cord.

    PubMed

    Balduini, W; De Angelis, V; Mazzoni, E; Depoortere, H; Cattabeni, F; Cimino, M

    2001-06-01

    Thiocolchicoside is used in humans as a myorelaxant drug with anti-inflammatory and analgesic activity. Recently we established the experimental conditions that allowed the identification of [3H]thiocolchicoside binding sites in synaptic membranes of rat spinal cord and cerebral cortex. The pharmacological characterization of these sites indicated that GABA and several of its agonists and antagonists, as well as strychnine, were able to interact with [3H]thiocolchicoside binding in a dose-dependent manner and with different affinities. In order to gain more insight into the nature and the anatomical distribution of the binding sites labeled by [3H]thiocolchicoside, in the present study we examined the localization of these sites on parasagittal and coronal sections of the rat brain and spinal cord, respectively, using receptor autoradiography. In the spinal cord an intense signal was observed in the gray matter, with the highest density occurring in the superficial layers of the dorsal horns. Strychnine completely displaced [3H]thiocolchicoside binding, whereas GABA only partially removed the radioligand from its binding sites. In the brain, specific binding occurred in several areas and was displaced by both GABA and strychnine. The distribution of [3H]thiocolchicoside binding sites in brain sections, however, did not match that found for [3H]muscimol. Furthermore, cold thiocolchicoside was not able to completely displace [3H]muscimol binding, and showed a different efficacy in the various areas labeled by the radioligand. We conclude that thiocolchicoside may interact with a subpopulation of GABA(A) receptors having low-affinity binding sites for GABA. Furthermore, the observed sensitivity to strychnine in the spinal cord indicates an interaction also with strychnine-sensitive glycine receptors, suggesting that the pharmacological effects of thiocolchicoside may be the result of its interaction with different receptor populations.

  12. Effects of morphine and endomorphins on the polysynaptic reflex in the isolated rat spinal cord.

    PubMed

    Tao, Pao-Luh; Lai, Yong-Shang; Chow, Lok-Hi; Huang, Eagle Yi-Kung

    2005-01-01

    At the spinal level, mu-opioids exert their actions on nociceptive primary afferent neurons both pre- and postsynaptically. In the present study, we used an in vitro isolated neonatal rat (11-15 days old) spinal cord preparation to examine the effects of morphine and the endogenous mu-opioid ligands endomorphin-1 (EM-1) and endomorphin-2 (EM-2) on the polysynaptic reflex (PSR) of dorsal root-ventral root (DR-VR) reflex. The actions of mu-opioids on spinal nociception were investigated by quantification of the firing frequency and the mean amplitude of the PSR evoked by stimuli with 20 x threshold intensity. EM-1 decreased the mean amplitude of PSR, whereas EM-2 and morphine decreased the firing frequency. The pattern of the effects elicited by morphine was the same as that for EM-2, except at high concentration. Naloxonazine, a selective mu(1) opioid receptor antagonist, had no significant effect on PSR by itself, but blocked the inhibition of PSR firing frequency or amplitude induced by EM-1, -2 and morphine. This may suggest that EM-1, EM-2 and morphine modulate spinal nociception differently and act mainly at the mu(1)-opioid receptors. Although they all act via mu(1)-opioid receptors, their different effects on the PSR may suggest the existence of different subtypes of the mu(1)-opioid receptor. The present data is also consistent with a further hypothesis, namely, that morphine and EM-2 activate a subtype of mu(1)-opioid receptor presynaptically, while EM-1 acts mainly through another subtype postsynaptically. However, since other reports indicate that EM-2, but not EM-1, could stimulate the release of enkephalins or dynorphin, presynaptic delta and kappa receptors may be also involved indirectly in the different regulation by mu-opioids at the spinal level.

  13. Intraplantar injection of anandamide inhibits mechanically-evoked responses of spinal neurones via activation of CB2 receptors in anaesthetised rats.

    PubMed

    Sokal, D M; Elmes, S J R; Kendall, D A; Chapman, V

    2003-09-01

    Anti-nociceptive effects of the endocannabinoid anandamide are well established. Anandamide has, however, also been shown to activate pro-nociceptive vanilloid 1 (VR1) receptors present on primary afferent nociceptors. The aim of the present study was to determine the effect of intraplantar injection of anandamide on dorsal spinal neuronal responses in control rats and rats with hindpaw carrageenan-induced inflammation. Effects of intraplantar administration of anandamide (50 microg in 50 microl) on peripheral mechanically-evoked responses of spinal neurones were studied in halothane-anaesthetised rats in vivo. Responses of spinal neurones to mechanical punctate stimulation (von Frey filaments, 8-80 g) of the peripheral receptive field were similar in non-inflamed rats and rats with hindpaw carrageenan-induced inflammation. Intraplantar injection of anandamide, but not vehicle, significantly (P<0.05) inhibited innocuous and noxious mechanically-evoked responses of spinal neurones in rats with hindpaw inflammation, but not in non-inflamed rats. Co-administration of the cannabinoid (2) (CB(2)) receptor antagonist, SR144528 (10 microg in 50 microl), but not the cannabinoid (1) (CB(1)) receptor antagonist, SR141716A (10 microg in 50 microl), significantly blocked inhibitory effects of anandamide on peripheral evoked neuronal responses in rats with hindpaw inflammation. This study demonstrates inhibitory effects of exogenous anandamide on mechanically-evoked responses under inflammatory conditions in vivo, which are mediated by peripheral CB(2) receptors.

  14. Innocuous, Not Noxious, Input Activates PKCγ Interneurons of the Spinal Dorsal Horn via Myelinated Afferent Fibers

    PubMed Central

    Braz, Joao M.; Skinner, Kate; Llewellyn-Smith, Ida J.; Basbaum, Allan I.

    2008-01-01

    Protein kinase C γ (PKCγ), which is concentrated in interneurons of the inner part of lamina II of the dorsal horn, has been implicated in injury-induced allodynia, a condition wherein pain is produced by innocuous stimuli. Although it is generally assumed that these interneurons receive input from the nonpeptidergic, IB4-positive subset of nociceptors, the fact that PKCγ cells do not express Fos in response to noxious stimulation suggests otherwise. Here, we demonstrate that the terminal field of the nonpeptidergic population of nociceptors, in fact, lies dorsal to that of PKCγ interneurons. There was also no overlap between the PKCγ-expressing interneurons and the transganglionic tracer wheat germ agglutinin which, after sciatic nerve injection, labels all unmyelinated nociceptors. However, transganglionic transport of the β-subunit of cholera toxin, which marks the medium-diameter and large-diameter myelinated afferents that transmit non-noxious information, revealed extensive overlap with the layer of PKCγ interneurons. Furthermore, expression of a transneuronal tracer in myelinated afferents resulted in labeling of PKCγ interneurons. Light and electron microscopic double labeling further showed that the VGLUT1 subtype of vesicular glutamate transmitter, which is expressed in myelinated afferents, marks synapses that are presynaptic to the PKCγ interneurons. Finally, we demonstrate that a continuous non-noxious input, generated by walking on a rotarod, induces Fos in the PKCγ interneurons. These results establish that PKCγ interneurons are activated by myelinated afferents that respond to innocuous stimuli, which suggests that injury-induced mechanical allodynia is transmitted through a circuit that involves PKCγ interneurons and non-nociceptive, VGLUT1-expressing myelinated primary afferents. PMID:18685019

  15. Modulation of synaptic transmission from segmental afferents by spontaneous activity of dorsal horn spinal neurones in the cat.

    PubMed

    Manjarrez, E; Rojas-Piloni, J G; Jimenez, I; Rudomin, P

    2000-12-01

    We examined, in the anaesthetised cat, the influence of the neuronal ensembles producing spontaneous negative cord dorsum potentials (nCDPs) on segmental pathways mediating primary afferent depolarisation (PAD) of cutaneous and group I muscle afferents and on Ia monosynaptic activation of spinal motoneurones. The intraspinal distribution of the field potentials associated with the spontaneous nCDPs indicated that the neuronal ensembles involved in the generation of these potentials were located in the dorsal horn of lumbar segments, in the same region of termination of low-threshold cutaneous afferents. During the occurrence of spontaneous nCDPs, transmission from low-threshold cutaneous afferents to second order neurones in laminae III-VI, as well as transmission along pathways mediating PAD of cutaneous and Ib afferents, was facilitated. PAD of Ia afferents was instead inhibited. Monosynaptic reflexes of flexors and extensors were facilitated during the spontaneous nCDPs. The magnitude of the facilitation was proportional to the amplitude of the 'conditioning' spontaneous nCDPs. This led to a high positive correlation between amplitude fluctuations of spontaneous nCDPs and fluctuations of monosynaptic reflexes. Stimulation of low-threshold cutaneous afferents transiently reduced the probability of occurrence of spontaneous nCDPs as well as the fluctuations of monosynaptic reflexes. It is concluded that the spontaneous nCDPs were produced by the activation of a population of dorsal horn neurones that shared the same functional pathways and involved the same set of neurones as those responding monosynaptically to stimulation of large cutaneous afferents. The spontaneous activity of these neurones was probably the main cause of the fluctuations of the monosynaptic reflexes observed under anaesthesia and could provide a dynamic linkage between segmental sensory and motor pathways.

  16. Modulation of synaptic transmission from segmental afferents by spontaneous activity of dorsal horn spinal neurones in the cat

    PubMed Central

    Manjarrez, E; Rojas-Piloni, J G; Jiménez, I; Rudomin, P

    2000-01-01

    We examined, in the anaesthetised cat, the influence of the neuronal ensembles producing spontaneous negative cord dorsum potentials (nCDPs) on segmental pathways mediating primary afferent depolarisation (PAD) of cutaneous and group I muscle afferents and on Ia monosynaptic activation of spinal motoneurones. The intraspinal distribution of the field potentials associated with the spontaneous nCDPs indicated that the neuronal ensembles involved in the generation of these potentials were located in the dorsal horn of lumbar segments, in the same region of termination of low-threshold cutaneous afferents. During the occurrence of spontaneous nCDPs, transmission from low-threshold cutaneous afferents to second order neurones in laminae III-VI, as well as transmission along pathways mediating PAD of cutaneous and Ib afferents, was facilitated. PAD of Ia afferents was instead inhibited. Monosynaptic reflexes of flexors and extensors were facilitated during the spontaneous nCDPs. The magnitude of the facilitation was proportional to the amplitude of the ‘conditioning’ spontaneous nCDPs. This led to a high positive correlation between amplitude fluctuations of spontaneous nCDPs and fluctuations of monosynaptic reflexes. Stimulation of low-threshold cutaneous afferents transiently reduced the probability of occurrence of spontaneous nCDPs as well as the fluctuations of monosynaptic reflexes. It is concluded that the spontaneous nCDPs were produced by the activation of a population of dorsal horn neurones that shared the same functional pathways and involved the same set of neurones as those responding monosynaptically to stimulation of large cutaneous afferents. The spontaneous activity of these neurones was probably the main cause of the fluctuations of the monosynaptic reflexes observed under anaesthesia and could provide a dynamic linkage between segmental sensory and motor pathways. PMID:11101653

  17. Neurogenic period of ascending tract neurons in the upper lumbar spinal cord of the rat

    SciTech Connect

    Nandi, K.N.; Beal, J.A.; Knight, D.S. )

    1990-02-01

    Although the neurogenic period for neurons in the lumbar spinal cord has been clearly established (Days 12 through 16 of gestation), it is not known when the neurogenesis of ascending tract neurons is completed within this period. The purpose of the present study was to determine the duration of the neurogenic period for projection neurons of the ascending tracts. To label neurons undergoing mitosis during this period, tritiated thymidine was administered to fetal rats on Embryonic (E) Days E13 through E16 of gestation. Ascending tract neurons of the lumbar cord were later (Postnatal Days 40-50) labeled in each animal with a retrograde tracer, Fluoro-Gold, applied at the site of a hemisection at spinal cord segment C3. Ascending tract neurons which were undergoing mitosis in the upper lumbar cord were double labeled, i.e., labeled with both tritiated thymidine and Fluoro-Gold. On Day E13, 89-92% of the ascending tract neurons were double labeled; on Day E14, 35-37%; and on Day E15, 1-4%. Results showed, then, that some ascending tract neurons were double labeled through Day E15 and were, therefore, proliferating in the final one-third of the neurogenic period. Ascending tract neurons proliferating on Day E15 were confined to laminae III, IV, V, and X and the nucleus dorsalis. Long tract neurons in the superficial dorsal horn (laminae I and II), on the other hand, were found to have completed neurogenesis on Day E14 of gestation. Results of the present study show that spinal neurogenesis of ascending projection neurons continues throughout most of the neurogenic period and does not completely follow the well-established ventral to dorsal gradient.

  18. The effect of morphine sensitization on extracellular concentrations of GABA in dorsal hippocampus of male rats.

    PubMed

    Farahmandfar, Maryam; Zarrindast, Mohammad-Reza; Kadivar, Mehdi; Karimian, Seyed Morteza; Naghdi, Nasser

    2011-11-01

    Repeated, intermittent exposure to drugs of abuse, such as morphine results in response enhancements to subsequent drug treatments, a phenomenon referred to as behavioral sensitization. As persistent neuronal sensitization may contribute to the long-lasting consequences of drug abuse, characterizing the neurochemical mechanisms of sensitization is providing insights into addiction. Although it has been shown that GABAergic systems in the CA1 region of dorsal hippocampus are involved in morphine sensitization, the alteration of extracellular level of GABA in this area in morphine sensitization has not been investigated. In the present study, using the in vivo microdialysis technique, we investigated the effect of morphine sensitization on extracellular GABA concentration in CA1 region of dorsal hippocampus of freely moving rats. Sensitization was induced by subcutaneous (s.c.) injection of morphine, once daily for 3 days followed by 5 days free of the opioid treatment. The results showed that extracellular GABA concentration in CA1 was decreased following acute administration of morphine in non-sensitized rats. However, morphine-induced behavioral sensitization significantly increased the extracellular GABA concentration in this area. The enhancement of GABA in morphine sensitized rats was inhibited by administration of naloxone 30 min before each of three daily doses of morphine. These results suggest an adaptation of the GABAergic neuronal transmission in dorsal hippocampus induced by morphine sensitization and it is implied that opioid receptors may play an important role in this effect.

  19. Phenotypic changes in dorsal root ganglion and spinal cord in the collagen antibody-induced arthritis mouse model.

    PubMed

    Su, Jie; Gao, Tianle; Shi, Tiejun; Xiang, Qiong; Xu, Xiaojun; Wiesenfeld-Hallin, Zsuzsanna; Hökfelt, Tomas; Svensson, Camilla I

    2015-07-01

    The mechanisms underlying rheumatoid arthritis (RA)-induced pain are still not fully elucidated, and accumulating data indicate that peripheral inflammation is not the only factor driving pain in these patients. The focus of our work is to investigate the molecular basis for long-term alterations in nociceptive pathways induced by polyarthritis using the collagen antibody-induced arthritis (CAIA) mouse model. In this model, mechanical hypersensitivity outlasts the joint inflammation by weeks. Here we examined expression levels of neuropeptides, ion channels, and nerve injury markers associated with neuropathic and/or inflammatory pain in dorsal root ganglia (DRGs) and spinal cord both during the peak of inflammation (day 15) and when the inflammation has resolved but the hypersensitivity persists (days 45-47). No apparent differences were observed in substance P, calcitonin gene-related peptide, or neuropeptide Y protein expression in DRGs and spinal cord of CAIA mice. However, the neuropeptide galanin, the ATP-gated ion channel P2X3, and calcium channel subunit α2δ1 were significantly increased in the CAIA DRGs as compared to controls, both 15 and 47 days after induction of arthritis. On day 15 there was an increase in expression of two factors associated with nerve injury and cell stress, activating transcription factor 3 and growth-associated protein 43 in DRGs, whereby the latter was still dramatically upregulated after 47 days. In conclusion, this study suggests that long-term joint inflammation has an impact on DRG neurons that resembles both inflammation and nerve injury-induced pain states. Thus, antibody-driven inflammation generates a pain state with a unique neurochemical profile.

  20. Cardiac spinal deafferentation reduces the susceptibility to sustained ventricular tachycardia in conscious rats

    PubMed Central

    Lujan, Heidi L.; Krishnan, Sandhya

    2011-01-01

    The response to myocardial ischemia is complex and involves the cardio-cardiac sympathetic reflex. Specifically, cardiac spinal (sympathetic) afferents are excited by ischemic metabolites and elicit an excitatory sympathetic reflex, which plays a major role in the genesis of ventricular arrhythmias. For example, brief myocardial ischemia leads to ATP release, which activates cardiac spinal afferents through stimulation of P2 receptors. Clinical work with patients and preclinical work with animals document that disruption of this reflex protects against ischemia-induced ventricular arrhythmias. However, the role of afferent signals in the initiation of sustained ventricular tachycardia has not been investigated. Therefore, we tested the hypothesis that cardiac spinal deafferentation reduces the susceptibility to sustained ventricular tachycardia in adult (12–15 wk of age), conscious, male Sprague-Dawley rats. To test this hypothesis, the susceptibility to ventricular tachyarrhythmias produced by occlusion of the left main coronary artery was determined in two groups of conscious rats: 1) deafferentation (bilateral excision of the T1-T5 dorsal root ganglia) and 2) control (sham deafferentation). The ventricular arrhythmia threshold (VAT) was defined as the time from coronary occlusion to sustained ventricular tachycardia resulting in a reduction in arterial pressure. Results document a significantly higher VAT in the deafferentation group (7.0 ± 0.7 min) relative to control (4.3 ± 0.3 min) rats. The decreased susceptibility to tachyarrhythmias with deafferentation was associated with a reduced cardiac metabolic demand (lower rate-pressure product and ST segment elevation) during ischemia. PMID:21677267

  1. Tubercular spinal epidural abscess involving the dorsal-lumbar-sacral region without osseous involvement.

    PubMed

    Arora, Sumit; Kumar, Ramesh

    2011-07-27

    Musculoskeletal tuberculosis is known for its ability to present in various forms and guises at different sites. Tubercular spinal epidural abscess (SEA) is an uncommon infectious entity. Its presence without associated osseous involvement may be considered an extremely rare scenario. We present a rare case of tubercular SEA in an immune-competent 35-year-old male patient. The patient presented with acute cauda equina syndrome and was shown to have multisegmental SEA extending from D5 to S2 vertebral level without any evidence of vertebral involvement on MRI. The patient made an uneventful recovery following surgical decompression and antitubercular chemotherapy. The diagnosis was confirmed by histopathological demonstration of Mycobacterium tuberculosis in drained pus. Such presentation of tubercular SEA has not been reported previously in the English language based medical literature to the best of our knowledge.

  2. Actions of endomorphins on synaptic transmission of Adelta-fibers in spinal cord dorsal horn neurons.

    PubMed

    Yajiri, Y; Huang, L Y

    2000-01-01

    The effects of endogenous mu-opioid ligands, endomorphins, on Adelta-afferent-evoked excitatory postsynaptic currents (EPSCs) were studied in substantia gelatinosa neurons in spinal cord slices. Under voltage-clamp conditions, endomorphins blocked the evoked EPSCs in a dose-dependent manner. To determine if the block resulted from changes in transmitter release from glutamatergic synaptic terminals, the opioid actions on miniature excitatory postsynaptic currents (mEPSCs) were examined. Endomorphins (1 microM) reduced the frequency but not the amplitude of mEPSCs, suggesting that endomorphins directly act on presynaptic terminals. The effects of endomorphins on the unitary (quantal) properties of the evoked EPSCs were also studied. Endomorphins reduced unitary content without significantly changing unitary amplitude. These results suggest that in addition to presynaptic actions on interneurons, endomorphins also inhibit evoked EPSCs by reducing transmitter release from Adelta-afferent terminals.

  3. Chlorpheniramine produces spinal motor, proprioceptive and nociceptive blockades in rats.

    PubMed

    Tzeng, Jann-Inn; Lin, Heng-Teng; Chen, Yu-Wen; Hung, Ching-Hsia; Wang, Jhi-Joung

    2015-04-05

    This study aimed to assess the local anesthetic effects of chlorpheniramine in spinal anesthesia and is compared with mepivacaine, a widely-used local anesthetic. Spinal anesthesia with chlorpheniramine and mepivacaine was constructed in a dosage-dependent fashion after the rats were injected intrathecally. The spinal block effect of chlorpheniramine in motor function, nociception, and proprioception was compared to that of mepivacaine. We revealed that intrathecal chlorpheniramine and mepivacaine exhibited a dose-dependent spinal block of motor function, nociception, and proprioception. On the 50% effective dose (ED50) basis, the ranks of potencies in motor function, nociception, and proprioception were chlorpheniramine>mepivacaine (P<0.01 for the differences). On the equianesthetic basis (ED25, ED50, ED75), the duration of spinal anesthesia with chlorpheniramine was greater than that of mepivacaine (P<0.01 for the differences). Instead of mepivacaine, chlorpheniramine produced a greater duration of sensory blockade than the motor blockade. These preclinical data showed that chlorpheniramine has a better sensory-selective action over motor block to produce more potent and long-lasting spinal anesthesia than mepivacaine.

  4. Neuroprotective Effects of Different Modalities of Acupuncture on Traumatic Spinal Cord Injury in Rats

    PubMed Central

    Jiang, Song-he; Tu, Wen-zhan; Zou, En-miao; Hu, Jie; Wang, Sai; Li, Jiang-ru; Wang, Wan-sheng; He, Rong; Cheng, Rui-dong; Liao, Wei-jing

    2014-01-01

    Spinal cord injury (SCI) can induce a series of histological, biochemical, and functional changes. Acupuncture is commonly used for SCI patients. Using male rats of spinal cord injury with the New York University (NYU) Impactor, we investigated the response of electroacupuncture (EA), manual acupuncture (MA), and transcutaneous acupoint electrical stimulation (TAES) at Shuigou (DU26) and Fengfu (DU16) acupoints to understand the effects and mechanisms of acupuncture in neuroprotection and neuronal function recovery after SCI. Histological study showed a restored neural morphology and an increase in the quantity of neurons after EA, MA, and TAES administrations. Acupuncture's antioxidation effects were demonstrated by alleviation of the post-SCI superoxide dismutase (SOD) activity increase and malondialdehyde (MDA) level decrease. The anti-inflammation effect of acupuncture was shown as the reduced expression of inflammatory cytokines including interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) when SCI was treated. And the antiapoptosis role was approved by TUNEL staining. Our data confirmed that the role of acupuncture in neuroprotection and dorsal neuronal function recovery after rat SCI, especially, EA stimulating at Shuigou (DU26) and Fengfu (DU16) can greatly promote neuronal function recovery, which may result from antioxidation, anti-inflammation, and antiapoptosis effects of acupuncture. PMID:24803946

  5. Pulsed radiofrequency attenuates diabetic neuropathic pain and suppresses formalin-evoked spinal glutamate release in rats

    PubMed Central

    Huang, Yu-Hsin; Hou, Shao-Yun; Cheng, Jen-Kun; Wu, Chih-Hsien; Lin, Chung-Ren

    2016-01-01

    BACKGROUND: Pulsed radiofrequency (PRF) has been used to treat chronic pain for years, but its effectiveness and mechanism in treating diabetic neuropathic pain are still unexplored. The aim of this study was to elucidate the modulation of diabetic neuropathic pain induced by streptozotocin and the release of spinal excitatory amino acids by PRF. METHODS: Diabetes was induced by intraperitoneal administration of streptozotocin. Pulsed radiofrequency was applied to L5 and L6 dorsal roots at 42 °C for 2 min. The responses of all of the groups to thermal, mechanical and cold stimuli were measured for a period of 6 d after this process. Seven days after PRF treatment, intrathecal microdialysis was used to examine the effect of pulsed radiofrequency on the formalin-evoked spinal release of excitatory amino acids and concurrent behaviour responses from diabetic rats. RESULTS: Three weeks after intraperitoneal streptozotocin treatment and before PRF application, mechanical, thermal and cold hypersensitivity occurred. Application of PRF significantly alleviated hyperglycaemia-induced mechanical, thermal and cold hypersensitivity and also attenuated the increase in formalin-evoked CSF glutamate concentration, compared with sham treated diabetic rats. CONCLUSION: It may be concluded that PRF has an analgesic effect on neuropathic pain by suppressing the nociception-induced release of excitatory neurotransmitters. PRF may provide a novel promising therapeutic approach for managing diabetic neuropathic pain. PMID:27994505

  6. 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

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

    PubMed

    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

  8. The ability of inhibitory controls to 'switch-off' activity in dorsal horn convergent neurones in the rat.

    PubMed

    Cadden, S W

    1993-11-19

    Unitary extracellular recordings were made from 51 convergent neurones in the dorsal horn of the lumbar spinal cords of urethane anaesthetized rats. All the cells tested responded to sustained noxious mechanical stimulation of their receptive fields on the ipsilateral hindpaw, but only 26/49 gave tonic responses lasting for more than 5 min. In all 26 cells, these tonic responses were depressed by diffuse noxious inhibitory controls (DNIC) triggered by applying noxious conditioning stimuli elsewhere on the body. In seven cells, the inhibitory effects could involve a complete abolition of activity and in five cells, when this occurred, activity did not return during 2.5-6-min periods of observation following removal of the conditioning stimuli. However, in those cases, activity could be restored to pre-conditioning levels by further manipulations of the receptive field-either removal and re-application of the original stimulus or brief application of an additional stimulus. These results show that inhibitory controls can 'switch-off' activity in at least a small proportion of dorsal horn convergent neurones. One possible explanation would be that in these neurones, responses to sustained noxious stimuli may depend on activity in a positive feedback circuit within the central nervous system, which when interrupted, may be restored only by additional afferent inputs. The existence of such a loop could also explain the finding of convergent convergent neurones which initially were not spontaneously active but which after stimulation of their receptive fields, developed on-going discharges which could be switched-off by DNIC.

  9. Expression of vimentin and glial fibrillary acidic protein in the developing rat spinal cord: an immunocytochemical study of the spinal cord glial system.

    PubMed Central

    Oudega, M; Marani, E

    1991-01-01

    The glial system in the developing rat spinal cord was studied using immunocytochemistry. Antibodies to vimentin and glial fibrillary acidic protein (GFAP) were used. At E11, vimentin was first found in the membrana limitans externa. In the matrix layer, short vimentin protrusions were found near the membrana limitans externa at E12. In addition, vimentin was scattered throughout the matrix layer, where it was also present as vimentin-positive tangles. Later in development, vimentin immunoreactivity was distributed in a distinct radial pattern in the matrix layer. During the first postnatal weeks, vimentin was replaced by GFAP which is therefore expressed in a similar radial pattern. This orderly structural organisation of vimentin and GFAP in the matrix layer could indicate the involvement of both proteins in morphogenetic processes such as neuron migration and cell organisation. In the mantle layer, a distinct radial vimentin immunoreactivity was replaced by GFAP immunoreactivity during the first 2 postnatal weeks. In addition, GFAP fibres appeared first, at E18, in the ventral mantle layer associated with the motor neuron columns. These glial fibres originated from a local source. In the dorsal mantle layer, GFAP-positive fibres were oriented tangentially, which is different from the overall radial arrangement. This expression pattern may be related to the ingrowth of primary afferents. In the ventral and dorsal raphe, a major vimentin expression was replaced by a minor presence of GFAP. Within the white matter, a vimentin-positive radial pattern was demonstrated which, after birth, was replaced by GFAP. This palisading pattern suggested an involvement of both proteins in the development and guidance of the ascending and descending spinal cord fibre systems. The general transition from the expression of vimentin to the expression of GFAP in the rat spinal cord takes place during the first 3 postnatal weeks. Images Fig. 2 (cont.) Fig. 2 Fig. 3 Fig. 4 (cont.) Fig

  10. COGNITIVE IMPAIRMENT AND MORPHOLOGICAL CHANGES IN THE DORSAL HIPPOCAMPUS OF VERY OLD FEMALE RATS

    PubMed Central

    Morel, Gustavo R.; Andersen, Tomás; Pardo, Joaquín; Zuccolilli, Gustavo O.; Cambiaggi, Vanina L.; Hereñú, Claudia B.; Goya, Rodolfo G.

    2015-01-01

    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 4–6 months old (young), 26 months old (old) and 29–32 months 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 (PT), 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 the 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

  11. Light-evoked somatosensory perception of transgenic rats that express channelrhodopsin-2 in dorsal root ganglion cells.

    PubMed

    Ji, Zhi-Gang; Ito, Shin; Honjoh, Tatsuya; Ohta, Hiroyuki; Ishizuka, Toru; Fukazawa, Yugo; Yawo, Hiromu

    2012-01-01

    In vertebrate somatosensory systems, each mode of touch-pressure, temperature or pain is sensed by sensory endings of different dorsal root ganglion (DRG) neurons, which conducted to the specific cortical loci as nerve impulses. Therefore, direct electrical stimulation of the peripheral nerve endings causes an erroneous sensation to be conducted by the nerve. We have recently generated several transgenic lines of rat in which channelrhodopsin-2 (ChR2) transgene is driven by the Thy-1.2 promoter. In one of them, W-TChR2V4, some neurons were endowed with photosensitivity by the introduction of the ChR2 gene, coding an algal photoreceptor molecule. The DRG neurons expressing ChR2 were immunohistochemically identified using specific antibodies to the markers of mechanoreceptive or nociceptive neurons. Their peripheral nerve endings in the plantar skin as well as the central endings in the spinal cord were also examined. We identified that ChR2 is expressed in a certain population of large neurons in the DRG of W-TChR2V4. On the basis of their morphology and molecular markers, these neurons were classified as mechanoreceptive but not nociceptive. ChR2 was also distributed in their peripheral sensory nerve endings, some of which were closely associated with CK20-positive cells to form Merkel cell-neurite complexes or with S-100-positive cells to form structures like Meissner's corpuscles. These nerve endings are thus suggested to be involved in the sensing of touch. Each W-TChR2V4 rat showed a sensory-evoked behavior in response to blue LED flashes on the plantar skin. It is thus suggested that each rat acquired an unusual sensory modality of sensing blue light through the skin as touch-pressure. This light-evoked somatosensory perception should facilitate study of how the complex tactile sense emerges in the brain.

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

    PubMed

    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

    2009-04-01

    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.

  13. 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

  14. 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.

  15. Role of protein kinase A in phosphorylation of NMDA receptor 1 subunits in dorsal horn and spinothalamic tract neurons after intradermal injection of capsaicin in rats.

    PubMed

    Zou, X; Lin, Q; Willis, W D

    2002-01-01

    Protein phosphorylation is a major mechanism for regulation of N-methyl-D-aspartate (NMDA) receptor function. The NMDA receptor 1 subunit (NR1) is phosphorylated by protein kinase A (PKA) on serine 890 and 897. We have recently reported that there is enhanced phosphorylation of NR1 on serine 897 in dorsal horn and spinothalamic tract (STT) neurons after intradermal injection of capsaicin (CAP) in rats [Zou et al. (2000) J. Neurosci. 20, 6989-6997]. Whether or not this phosphorylation, which develops during central sensitization following CAP injection, is mediated by PKA remains to be determined. In this study, western blots and immunofluorescence staining were employed to observe if pretreatment with a PKA inhibitor, N-[2-((p-bromocinnamyl)amino)ethyl]-5-isoquinolinesulfonamide, HCl (H89), blocks the enhanced phosphorylation of NR1 on serine 897 following injection of CAP into the glabrous skin of one hind paw of anesthetized rats. Western blots showed that pretreatment with H89 caused a decrease in CAP-induced phosphorylation of NR1 protein in spinal cord segments L(4)-S(1). In experiments using immunofluorescence staining, the numbers of phospho-NR1-like immunoreactive (p-NR1-LI) neurons seen after CAP injection were significantly decreased in the dorsal horn of the L(4)-L(5) segments on the side ipsilateral to the injection after PKA was inhibited. When STT cells were labeled by microinjection of the retrograde tracer, fluorogold, we found that the proportion of p-NR1-LI STT cells on the side ipsilateral to the injection in the superficial laminae of spinal cord segments L(4)-L(5) was markedly reduced when H89 was administered intrathecally before CAP injection. However, the proportion of p-NR1-LI STT cells in deep laminae was unchanged unless the PKC inhibitor, chelerythrine chloride, was co-administered with H89. Combined with our previous findings, the present results indicate that NR1 in spinal dorsal horn neurons, including the superficial dorsal horn STT

  16. Transcriptional Expression of Voltage-gated Na+ and Voltage-independent K+ Channels in the Developing Rat Superficial Dorsal Horn

    PubMed Central

    Blankenship, Meredith L.; Coyle, Dennis E.; Baccei, Mark L.

    2013-01-01

    Neurons within the superficial dorsal horn (SDH) of the rodent spinal cord exhibit distinct firing properties during early life. While this may reflect a unique combination of voltage-gated Na+ (Nav) and voltage-independent (i.e. “leak”) K+ channels which strongly influence neuronal excitability across the CNS, surprisingly little is known about which genes encoding for Nav and leak K+ channels are expressed within developing spinal pain circuits. The goal of the present study was therefore to characterize the transcriptional expression of these channels within the rat SDH at postnatal days (P)3, 10, 21 or adulthood using quantitative PCR (qPCR). The results demonstrate that Nav isoforms are developmentally regulated at the mRNA level in a subtype-specific manner, as Nav1.2 and Nav1.3 decreased significantly from P3 to adulthood, while Nav1.1 was up-regulated during this period. The data also indicate selective, age-dependent changes in the mRNA expression of two-pore domain (K2P) K+ channels, as TASK-1 (KCNK3) and TASK-3 (KCNK9) were down-regulated during postnatal development in the absence of any changes in the TWIK isoforms examined (KCNK1 and KCNK6). In addition, a developmental shift occurred within the TREK subfamily due to decreased TREK-2 (KCNK10) mRNA within the mature SDH. Meanwhile, G-protein-coupled inward rectifying K+ channels (Kir3.1 and Kir3.2) were expressed in the SDH at mature levels from birth. Overall, the results suggest that the transcription of ion channel genes occurs in a highly age-dependent manner within the SDH, raising the possibility that manipulating the expression or function of ion channels which are preferentially expressed within immature nociceptive networks could yield novel approaches to relieving pain in infants and children. PMID:23219908

  17. Descending serotonergic controls regulate inflammation-induced mechanical sensitivity and methyl-CpG-binding protein 2 phosphorylation in the rat superficial dorsal horn

    PubMed Central

    Géranton, Sandrine M; Fratto, Vincenza; Tochiki, Keri K; Hunt, Stephen P

    2008-01-01

    Background Regulation of pain states is, in part, dependent upon plastic changes in neurones within the superficial dorsal horn. There is also compelling evidence that pain states are under the control of descending projections from the brainstem. While a number of transcription factors including Methyl-CpG-binding protein 2 (MeCP2), Zif268 and Fos have been implicated in the regulation of dorsal horn neurone sensitization following injury, modulation of their activity by descending controls has not been investigated. Results Here, we describe how descending controls regulate MeCP2 phosphorylation (P-MeCP2), known to relieve transcriptional repression by MeCP2, and Zif268 and Fos expression in the rat superficial dorsal horn, after CFA injection into the hind paw. First, we report that CFA significantly increased P-MeCP2 in Lamina I and II, from 30 min post injection, with a maximum reached after 1 h. The increase in P-MeCP2 paralleled that of Zif268 and Fos, and P-MeCP2 was expressed in large sub-populations of Zif268 and Fos expressing neurones. Serotonergic depletion of the lumbar spinal cord with 5,7 di-hydroxytryptamine creatinine sulphate (5,7-DHT) reduced the inflammation evoked P-MeCP2 in the superficial dorsal horn by 57%, and that of Zif268 and Fos by 37.5% and 30% respectively. Although 5,7-DHT did not change primary thermal hyperalgesia, it significantly attenuated mechanical sensitivity seen in the first 24 h after CFA. Conclusion We conclude that descending serotonergic pathways play a crucial role in regulating gene expression in the dorsal horn and mechanical sensitivity associated with an inflammatory pain state. PMID:18793388

  18. 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.

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

    PubMed

    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.

  20. Evidence that inhibitory mechanisms mask inappropriate somatotopic connections in the spinal cord of normal rat.

    PubMed

    Biella, G; Sotgiu, M L

    1995-08-01

    1. The responses to stimulation of the sciatic and saphenous nerves have been studied in 65 pairs of spinal dorsal horn neurons simultaneously recorded at the L2 and L5-L6 lumbar segments of the rat's spinal cord. The neurons were recorded in anesthetized and paralyzed animals. 2. Five- or seven-barreled micropipettes were utilized for recording and for the application of drugs with iontophoresis or micropressure techniques. The drugs used were: strychnine, as a selective antagonist at glycine receptors; sodium glutamate and N-methyl-D-aspartate (NMDA), as agonists at excitatory glutamatergic receptors; glycine, as an agonist at the inhibitory glycine receptor; and the local anesthetic lidocaine, as a reversible local conduction blocker both in the periphery and in the spinal cord. 3. All neurons had cutaneous receptive fields in the ipsilateral hindpaw. Neurons responding exclusively to saphenous stimulation in L2 and to sciatic stimulation in L5-L6 were selected for this study. The responses consisted of bursts of > or = 5 spikes, often partially inserted in a field potential, with latencies of 5.0 +/- 1.1 (SD) and 5.2 +/- 1.2 ms, respectively. The thresholds of stimulation and the response latencies were controlled to be stable throughout the experiments. 4. Eighty-five percent (29 of 35) of the neurons tested in L5-L6 exhibited responses to saphenous stimulation during strychnine microejection in the recorded neurons. The neurons became again unresponsive to saphenous stimulation shortly after the end of strychnine ejection. 5. All the neurons tested in L5-L6 (n = 14) showed a significant increase in background activity and remained unresponsive to saphenous stimulation during glutamate microejection on the recorded neurons. 6. All the neurons tested in L5-L6 (n = 17) showed responses to saphenous stimulation after sciatic nerve block with local anesthetic. The responses to saphenous stimulation disappeared after the effect of local anesthetic ceased. 7. All

  1. Effects of dorsal hippocampus catecholamine depletion on paired-associates learning and place learning in rats.

    PubMed

    Roschlau, Corinna; Hauber, Wolfgang

    2017-04-14

    Growing evidence suggests that the catecholamine (CA) neurotransmitters dopamine and noradrenaline support hippocampus-mediated learning and memory. However, little is known to date about which forms of hippocampus-mediated spatial learning are modulated by CA signaling in the hippocampus. Therefore, in the current study we examined the effects of 6-hydroxydopamine-induced CA depletion in the dorsal hippocampus on two prominent forms of hippocampus-based spatial learning, that is learning of object-location associations (paired-associates learning) as well as learning and choosing actions based on a representation of the context (place learning). Results show that rats with CA depletion of the dorsal hippocampus were able to learn object-location associations in an automated touch screen paired-associates learning (PAL) task. One possibility to explain this negative result is that object-location learning as tested in the touchscreen PAL task seems to require relatively little hippocampal processing. Results further show that in rats with CA depletion of the dorsal hippocampus the use of a response strategy was facilitated in a T-maze spatial learning task. We suspect that impaired hippocampus CA signaling may attenuate hippocampus-based place learning and favor dorsolateral striatum-based response learning.

  2. Differential effects of opioids on sacrocaudal afferent pathways and central pattern generators in the neonatal rat spinal cord.

    PubMed

    Blivis, D; Mentis, G Z; O'donovan, M J; Lev-Tov, A

    2007-04-01

    The effects of opioids on sacrocaudal afferent (SCA) pathways and the pattern-generating circuitry of the thoracolumbar and sacrocaudal segments of the spinal cord were studied in isolated spinal cord and brain stem-spinal cord preparations of the neonatal rat. The locomotor and tail moving rhythm produced by activation of nociceptive and nonnociceptive sacrocaudal afferents was completely blocked by specific application of the mu-opioid receptor agonist [d-Ala(2), N-Me-Phe(4), Gly(5)-ol]-enkephalin acetate salt (DAMGO) to the sacrocaudal but not the thoracolumbar segments of the spinal cord. The rhythmic activity could be restored after addition of the opioid receptor antagonist naloxone to the experimental chamber. The opioid block of the SCA-induced rhythm is not due to impaired rhythmogenic capacity of the spinal cord because a robust rhythmic activity could be initiated in the thoracolumbar and sacrocaudal segments in the presence of DAMGO, either by stimulation of the ventromedial medulla or by bath application of N-methyl-d-aspartate/serotonin. We suggest that the opioid block of the SCA-induced rhythm involves suppression of synaptic transmission through sacrocaudal interneurons interposed between SCA and the pattern-generating circuitry. The expression of mu opioid receptors in several groups of dorsal, intermediate and ventral horn interneurons in the sacrocaudal segments of the cord, documented in this study, provides an anatomical basis for this suggestion.

  3. Changes in the Expressions of Iba1 and Calcitonin Gene-Related Peptide in Adjacent Lumbar Spinal Segments after Lumbar Disc Herniation in a Rat Model.

    PubMed

    Cho, Hee Kyung; Ahn, Sang Ho; Kim, So-Yeon; Choi, Mi-Jung; Hwang, Se Jin; Cho, Yun Woo

    2015-12-01

    Lumbar disc herniation is commonly encountered in clinical practice and can induce sciatica due to mechanical and/or chemical irritation and the release of proinflammatory cytokines. However, symptoms are not confined to the affected spinal cord segment. The purpose of this study was to determine whether multisegmental molecular changes exist between adjacent lumbar spinal segments using a rat model of lumbar disc herniation. Twenty-nine male Sprague-Dawley rats were randomly assigned to either a sham-operated group (n=10) or a nucleus pulposus (NP)-exposed group (n=19). Rats in the NP-exposed group were further subdivided into a significant pain subgroup (n=12) and a no significant pain subgroup (n=7) using mechanical pain thresholds determined von Frey filaments. Immunohistochemical stainings of microglia (ionized calcium-binding adapter molecule 1; Iba1), astrocytes (glial fibrillary acidic protein; GFAP), calcitonin gene-related peptide (CGRP), and transient receptor potential vanilloid 1 (TRPV1) was performed in spinal dorsal horns and dorsal root ganglions (DRGs) at 10 days after surgery. It was found immunoreactivity for Iba1-positive microglia was higher in the L5 (P=0.004) dorsal horn and in the ipsilateral L4 (P=0.009), L6 (P=0.002), and S1 (P=0.002) dorsal horns in the NP-exposed group than in the sham-operated group. The expression of CGRP was also significantly higher in ipsilateral L3, L4, L6, and S1 segments and in L5 DRGs at 10 days after surgery in the NP-exposed group than in the sham-operated group (P<0.001). Our results indicate that lumbar disc herniation upregulates microglial activity and CGRP expression in many adjacent and ipsilateral lumbar spinal segments.

  4. Changes in the Expressions of Iba1 and Calcitonin Gene-Related Peptide in Adjacent Lumbar Spinal Segments after Lumbar Disc Herniation in a Rat Model

    PubMed Central

    2015-01-01

    Lumbar disc herniation is commonly encountered in clinical practice and can induce sciatica due to mechanical and/or chemical irritation and the release of proinflammatory cytokines. However, symptoms are not confined to the affected spinal cord segment. The purpose of this study was to determine whether multisegmental molecular changes exist between adjacent lumbar spinal segments using a rat model of lumbar disc herniation. Twenty-nine male Sprague-Dawley rats were randomly assigned to either a sham-operated group (n=10) or a nucleus pulposus (NP)-exposed group (n=19). Rats in the NP-exposed group were further subdivided into a significant pain subgroup (n=12) and a no significant pain subgroup (n=7) using mechanical pain thresholds determined von Frey filaments. Immunohistochemical stainings of microglia (ionized calcium-binding adapter molecule 1; Iba1), astrocytes (glial fibrillary acidic protein; GFAP), calcitonin gene-related peptide (CGRP), and transient receptor potential vanilloid 1 (TRPV1) was performed in spinal dorsal horns and dorsal root ganglions (DRGs) at 10 days after surgery. It was found immunoreactivity for Iba1-positive microglia was higher in the L5 (P=0.004) dorsal horn and in the ipsilateral L4 (P=0.009), L6 (P=0.002), and S1 (P=0.002) dorsal horns in the NP-exposed group than in the sham-operated group. The expression of CGRP was also significantly higher in ipsilateral L3, L4, L6, and S1 segments and in L5 DRGs at 10 days after surgery in the NP-exposed group than in the sham-operated group (P<0.001). Our results indicate that lumbar disc herniation upregulates microglial activity and CGRP expression in many adjacent and ipsilateral lumbar spinal segments. PMID:26713069

  5. Local peripheral opioid effects and expression of opioid genes in the spinal cord and dorsal root ganglia in neuropathic and inflammatory pain.

    PubMed

    Obara, Ilona; Parkitna, Jan Rodriguez; Korostynski, Michal; Makuch, Wioletta; Kaminska, Dorota; Przewlocka, Barbara; Przewlocki, Ryszard

    2009-02-01

    We investigated the efficacy of local intraplantar (i.pl.) injection of peptide and non-peptide mu-, delta- and kappa-opioid receptor agonists in rat models of inflammatory and neuropathic pain. Locally applied agonists dose-dependently reduced formalin-induced flinching of the inflamed paw and induced antiallodynic and antihyperalgesic effects in sciatic nerve ligation-induced neuropathic pain. These effects were mediated by peripheral opioid receptors localized at the side of tissue/nerve injury, as was demonstrated by selective and non-selective opioid receptors antagonists. The ED(50) dose range of mu- and kappa-agonists required to induce analgesia in neuropathy was much higher than the ED(50) for inflammation; moreover, only delta-agonists were effective in the same dose range in both pain models. Additionally, effective antinociception was achieved at a lower dose of peptide, compared to non-peptide, opioids. Such findings support the use of the peripheral administration of opioid peptides, especially delta-agonists, in treating chronic pain. Furthermore, in order to assess whether adaptations in the expression of opioid genes could underlie the clinical observation of reduced opioid effectiveness in neuropathic pain, we analyzed the abundance of opioid transcripts in the spinal cord and dorsal root ganglia (DRG) during the neuropathy and inflammation. Nerve injury down-regulated mRNA for all types of opioid receptors in the DRG, which is predicted to decrease in the synthesis of opioid receptors to possibly account for the reduced effectiveness of locally administered opioids in neuropathy. The obtained results differentiate inflammatory and neuropathic pain and provide a novel insight into the peripheral effectiveness of opioids in both types of pain.

  6. Promazine and chlorpromazine for prolonged spinal anesthesia in rats.

    PubMed

    Chen, Yu-Wen; Chu, Chin-Chen; Chen, Yu-Chung; Kan, Chung-Dann; Wang, Jhi-Joung

    2012-07-19

    Though promazine and chlorpromazine elicited cutaneous anesthesia, no study of spinal anesthesia with chlorpromazine and promazine has been reported. This study was to examine whether chlorpromazine and promazine produce spinal anesthesia. Using a rat model via intrathecal injection, we tested spinal blockades of motor function and nociception by promazine, chlorpromazine or bupivacaine, and so were dose-response studies and durations. We demonstrated that chlorpromazine and promazine elicited dose-dependent spinal blockades in motor function and nociception. On the 50% effective dose (ED(50)) basis, the rank of potency of these drugs was bupivacaine>promazine>chlorpromazine (P<0.05 for the differences). On an equipotent basis (25% effective dose [ED(25)], ED(50), and ED(75)), the block duration caused by chlorpromazine or promazine was longer than that caused by the long-lasting local anesthetic bupivacaine (P<0.01 for the differences). Chlorpromazine and promazine, as well as bupivacaine, showed longer duration of sensory block than that of motor block. Our data reported that intrathecal promazine and chlorpromazine with a more sensory-selective action over motor blockade had less potent and longer-lasting spinal blockades when compared with bupivacaine.

  7. Cannabinoid CB2 receptor activation inhibits mechanically evoked responses of wide dynamic range dorsal horn neurons in naïve rats and in rat models of inflammatory and neuropathic pain.

    PubMed

    Elmes, Steven J R; Jhaveri, Maulik D; Smart, Darren; Kendall, David A; Chapman, Victoria

    2004-11-01

    Peripheral cannabinoid 2 receptors (CB2 receptors) modulate immune responses and attenuate nociceptive behaviour in models of acute and persistent pain. The aim of the present study was to investigate whether peripheral CB2 receptors modulate spinal processing of innocuous and noxious responses and to determine whether there are altered roles of CB2 receptors in models of persistent pain. Effects of local administration of the CB2 receptor agonist JWH-133 (5 and 15 microg/50 microL) on mechanically evoked responses of spinal wide dynamic range (WDR) neurons in noninflamed rats, rats with carrageenan-induced hindpaw inflammation, sham operated rats and spinal nerve-ligated (SNL) rats were determined in anaesthetized rats in vivo. Mechanical stimulation (von Frey filaments, 6-80 g) of the peripheral receptive field evoked firing of WDR neurons. Mechanically evoked responses of WDR neurons were similar in noninflamed, carrageenan-inflamed, sham-operated and SNL rats. Intraplantar injection of JWH-133 (15 microg), but not vehicle, significantly (P < 0.05) inhibited innocuous and noxious mechanically evoked responses of WDR neurons in all four groups of rats. In many cases the selective CB2 receptor antagonist, SR144528 (10 microg/50 microL), attenuated the inhibitory effects of JWH-133 (15 microg) on mechanically evoked WDR neuronal responses. The CB1 receptor antagonist, SR141716A, did not attenuate the inhibitory effects of JWH-133 on these responses. Intraplantar preadministration of JWH-133 also inhibited (P < 0.05) carrageenan-induced expansion of peripheral receptive fields of WDR dorsal horn neurons. This study demonstrates that activation of peripheral CB2 receptors attenuates both innocuous- and noxious-evoked responses of WDR neurons in models of acute, inflammatory and neuropathic pain.

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

    PubMed

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

    2015-12-01

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

  9. The effects of bilateral lesions to the dorsal tegmental nucleus on spatial learning in rats.

    PubMed

    Dwyer, Jessica A; Ingram, Matthew L; Snow, Anna C; Thorpe, Christina M; Martin, Gerard M; Skinner, Darlene M

    2013-12-01

    The head-direction (HD) signal is believed to originate in the dorsal tegmental nucleus (DTN) and lesions to this structure have been shown to disrupt HD cell firing in other areas along the HD cell circuit. To investigate the role of the DTN in spatial navigation, rats with bilateral, electrolytic (Experiment 1), or neurotoxic (Experiment 2) lesions to the DTN were compared with sham controls on two tasks that differed in difficulty and could be solved using directional heading. Rats were first trained on a direction problem in a water T maze where they learned to travel either east or west from two locations in the experimental room. DTN-lesioned rats were impaired relative to sham controls, both early in training, on the first block of eight trials, and on the total trials taken to reach criterion. In the food-foraging task, rats were trained to leave a home cage at the periphery of a circular table, find food in the center of the table and return to the home cage. Again, DTN-lesioned rats were impaired relative to sham rats, making more errors on the return component of the foraging trip. These data extend previous cell-recording studies and behavioral tests in which rats with electrolytic DTN lesions were used, and they demonstrate the importance of the direction system to spatial learning.

  10. 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

  11. 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.

  12. Chronic spinal infusion of loperamide alleviates postsurgical pain in rats.

    PubMed

    Kumar, Rakesh; Reeta, K H; Ray, Subrata Basu

    2014-04-01

    Plantar incision in rat generates spontaneous pain behaviour. The opioid drug, morphine used to treat postsurgical pain produces tolerance after long-term administration. Loperamide, a potent mu-opioid agonist, has documented analgesic action in various pain conditions. However, loperamide analgesia and associated tolerance following continuous spinal administration in postsurgical pain has not been reported. Chronic spinal infusion of drugs was achieved using intrathecal catheters connected to osmotic minipump. Coinciding with the onset of spinal infusion of loperamide or morphine, rats were subjected to plantar incision. Pain-related behaviour was assessed by Hargreaves apparatus (thermal hyperalgesia) and von Frey filaments (mechanical allodynia). Morphine and loperamide (0.5, 1 and 2 microL/h) induced analgesia was observed until 7th day post-plantar incision in Sprague-Dawley rats. Morphine and loperamide produced dose-dependent analgesia. Loperamide, in the highest dose, produced analgesia till 7th day. However, the highest dose of morphine produced inhibition of thermal hyperalgesia till 5th day and mechanical allodynia only till 3rd day post-plantar incision. Morphine and loperamide produced analgesia in postsurgical pain, which may be mediated through different mechanisms. Longer duration of analgesia with loperamide could probably be due sustained blockade of calcium channels.

  13. The articulo-cardiac sympathetic reflex in spinalized, anesthetized rats.

    PubMed

    Nakayama, Tomohiro; Suzuki, Atsuko; Ito, Ryuzo

    2006-04-01

    Somatic afferent regulation of heart rate by noxious knee joint stimulation has been proven in anesthetized cats to be a reflex response whose reflex center is in the brain and whose efferent arc is a cardiac sympathetic nerve. In the present study we examined whether articular stimulation could influence heart rate by this efferent sympathetic pathway in spinalized rats. In central nervous system (CNS)-intact rats, noxious articular movement of either the knee or elbow joint resulted in an increase in cardiac sympathetic nerve activity and heart rate. However, although in acutely spinalized rats a noxious movement of the elbow joint resulted in a significant increase in cardiac sympathetic nerve activity and heart rate, a noxious movement of the knee joint had no such effect and resulted in only a marginal increase in heart rate. Because this marginal increase was abolished by adrenalectomy suggests that it was due to the release of adrenal catecholamines. In conclusion, the spinal cord appears to be capable of mediating, by way of cardiac sympathetic nerves, the propriospinally induced reflex increase in heart rate that follows noxious stimulation of the elbow joint, but not the knee joint.

  14. Changes in correlation between spontaneous activity of dorsal horn neurones lead to differential recruitment of inhibitory pathways in the cat spinal cord.

    PubMed

    Chávez, D; Rodríguez, E; Jiménez, I; Rudomin, P

    2012-04-01

    Simultaneous recordings of cord dorsum potentials along the lumbo-sacral spinal cord of the anaesthetized cat revealed the occurrence of spontaneous synchronous negative (n) and negative-positive (np) cord dorsum potentials (CDPs). The npCDPs, unlike the nCDPs, appeared preferentially associated with spontaneous negative dorsal root potentials (DRPs) resulting from primary afferent depolarization. Spontaneous npCDPs recorded in preparations with intact neuroaxis or after spinalization often showed a higher correlation than the nCDPs recorded from the same pair of segments. The acute section of the sural and superficial peroneal nerves further increased the correlation between paired sets of npCDPs and reduced the correlation between the nCDPs recorded from the same pair of segments. It is concluded that the spontaneous nCDPs and npCDPs are produced by the activation of interconnected sets of dorsal horn neurones located in Rexed's laminae III–IV and bilaterally distributed along the lumbo-sacral spinal cord. Under conditions of low synchronization in the activity of this network of neurones there would be a preferential activation of the intermediate nucleus interneurones mediating Ib non-reciprocal postsynaptic inhibition. Increased synchronization in the spontaneous activity of this ensemble of dorsal horn neurones would recruit the interneurones mediating primary afferent depolarization and presynaptic inhibition and, at the same time, reduce the activation of pathways mediating Ib postsynaptic inhibition. Central control of the synchronization in the spontaneous activity of dorsal horn neurones and its modulation by cutaneous inputs is envisaged as an effective mechanism for the selection of alternative inhibitory pathways during the execution of specific motor or sensory tasks.

  15. Changes in correlation between spontaneous activity of dorsal horn neurones lead to differential recruitment of inhibitory pathways in the cat spinal cord

    PubMed Central

    Chávez, D; Rodríguez, E; Jiménez, I; Rudomin, P

    2012-01-01

    Simultaneous recordings of cord dorsum potentials along the lumbo-sacral spinal cord of the anaesthetized cat revealed the occurrence of spontaneous synchronous negative (n) and negative–positive (np) cord dorsum potentials (CDPs). The npCDPs, unlike the nCDPs, appeared preferentially associated with spontaneous negative dorsal root potentials (DRPs) resulting from primary afferent depolarization. Spontaneous npCDPs recorded in preparations with intact neuroaxis or after spinalization often showed a higher correlation than the nCDPs recorded from the same pair of segments. The acute section of the sural and superficial peroneal nerves further increased the correlation between paired sets of npCDPs and reduced the correlation between the nCDPs recorded from the same pair of segments. It is concluded that the spontaneous nCDPs and npCDPs are produced by the activation of interconnected sets of dorsal horn neurones located in Rexed's laminae III–IV and bilaterally distributed along the lumbo-sacral spinal cord. Under conditions of low synchronization in the activity of this network of neurones there would be a preferential activation of the intermediate nucleus interneurones mediating Ib non-reciprocal postsynaptic inhibition. Increased synchronization in the spontaneous activity of this ensemble of dorsal horn neurones would recruit the interneurones mediating primary afferent depolarization and presynaptic inhibition and, at the same time, reduce the activation of pathways mediating Ib postsynaptic inhibition. Central control of the synchronization in the spontaneous activity of dorsal horn neurones and its modulation by cutaneous inputs is envisaged as an effective mechanism for the selection of alternative inhibitory pathways during the execution of specific motor or sensory tasks. PMID:22271870

  16. Spinal segmental and supraspinal mechanisms underlying the pain-relieving effects of spinal cord stimulation: an experimental study in a rat model of neuropathy.

    PubMed

    Barchini, J; Tchachaghian, S; Shamaa, F; Jabbur, S J; Meyerson, B A; Song, Z; Linderoth, B; Saadé, N E

    2012-07-26

    Spinal cord stimulation (SCS) may alleviate certain forms of neuropathic pain; its mechanisms of action are, however, not fully understood. Previous studies have mainly been focused onto segmental spinal mechanisms, though there is evidence indicating a supraspinal involvement. This study aims to evaluate the relative importance of segmental and supraspinal mechanisms related to the activation of the dorsal columns (DCs). Rats were used to induce the spared nerve injury neuropathy and simultaneously subjected to chronic bilateral DC lesions at the C6-C8 level. Two pairs of miniature electrodes were implanted in each animal, with a monopolar system placed in the dorsal epidural space at a low thoracic level (below lesion) and a bipolar system placed onto the dorsal column nuclei (above lesion). Stimulation (50 Hz, 0.2 ms, 2-4V, 5 min) was applied via either type of electrodes, and tests for sensitivity to tactile and thermal stimuli were used to assess its inhibitory effects. Various receptor antagonists {bicuculline (GABA(A)), saclofen (GABA(B)), ketanserine (5HT(2)), methysergide (5HT(1-2)), phentolamine (α-adrenergic), propranolol (β-adrenergic), sulpiride (D(2)/D(3) dopamine) or saline were injected prior to the SCS. Rostral and caudal stimulations produced a comparable inhibition of neuropathic manifestations, and these effects were attenuated by about 50% after DC lesions. Pretreatment with the various receptor antagonists differentially influenced the effects of rostral and caudal stimulation. Our findings suggest that both supraspinal and segmental mechanisms are activated by SCS, and that in this model with DC lesions, rostral and caudal stimulations may activate different synaptic circuitries and transmitter systems.

  17. 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

  18. [Biomechanical characteristics of spinal cord tissue--basis for the development of modifications of the DREZ (dorsal root entry zone) operation].

    PubMed

    Spaić, M; Mikicić, D; Ilić, S; Milosavljević, I; Ivanović, S; Slavik, E; Antić, B

    2004-01-01

    Mechanical properties of the spinal cord tissue--biological basis for the development of the modality of the DREZ surgery lesioning technique Succesful treatment of the chronic neurogenic pain of spinal cord and cauda equina injury origin remains a significant management problem. The mechanism of this pain phenomenon has been shown to be related to neurochemical changes that lead to the state of hypereactivity of the second order dorsal horn neurons. The DREZ surgery (Dorsal Root Entry Zone lesion), designed to destroy anatomy structures involved in pain generating thus interrupting the neurogenic pain mechanism, as a causative procedure in treating this chronic pain, has been performed by using different technical modalities: Radiofrequency (RF) coagulation technic, Laser, Ultrasound and Microsurgical DREZotomy technic. The purpose of the study was to assess the possibility for the establishment of the lesioning technic based on the natural difference in the mechanical properties between the white and gray cord substance. We experimentally deteminated mechanical properties of the human cadaveric cord white versus gray tissue for the purpose of testing possibility of selective suction of the dorsal horn gray substance as a DREZ lesioning procedure. Based on the fact of the difference in tissue elasticity between white and gray cord substance we established a new and simple DREZ surgical lesioning technique that was tested on cadaver cord. For the purpose of testing and comparing the size and shape of the DREZ lesion axchieved the DREZ surgery has been performed on cadaver cord by employing selective dorsal horn suction as a lesioning method. After the procedure cadaver cord underwent histological fixation and analysis of the DREZ lesions achieved. Our result revealed that the white cord substance with longitudinal fiber structure had four time higher dynamical viscosity than gray substance of local neuronal network structure (150 PaS versus 37.5 PaS) that provided

  19. 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

  20. Rabbit IgG distribution in skin, spinal cord and DRG following systemic injection in rat.

    PubMed

    Tonra, J R; Mendell, L M

    1997-12-01

    In order to determine the distribution of antibodies such as anti-NGF following systemic injection in neonates, immunocytochemical techniques were used to examine the localization of rabbit IgG in rat skin, DRG, and spinal cord after treatments with normal rabbit serum or purified rabbit IgG. Daily subcutaneous injections beginning on postnatal day 2 or on day 15 were given for three days. On the fourth day the animals were sacrificed and tissues were processed for rabbit IgG-IR. In the dorsal and ventral spinal cord, staining intensities suggest a substantial increase in the blood-brain barrier during the first two weeks after birth. Staining intensity in the epidermis of the glabrous skin from the hindpaw was substantially lower than in the adjacent dermis. In addition, IgG infrequently accumulated intracellularly in intensely stained patches in the epidermis. IgG was also able to reach relatively high intracellular concentrations in a small number of sensory neurons. The IgG staining pattern in the skin was similar when anti-NGF itself was administered to the animals. The results are discussed in the context of the effects of anti-NGF on the development of nociceptive afferents.

  1. 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

  2. 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.

  3. A mesenchymal-like ZEB1(+) niche harbors dorsal radial glial fibrillary acidic protein-positive stem cells in the spinal cord.

    PubMed

    Sabourin, Jean-Charles; Ackema, Karin B; Ohayon, David; Guichet, Pierre-Olivier; Perrin, Florence E; Garces, Alain; Ripoll, Chantal; Charité, Jeroen; Simonneau, Lionel; Kettenmann, H; Zine, Azel; Privat, Alain; Valmier, Jean; Pattyn, Alexandre; Hugnot, Jean-Philippe

    2009-11-01

    In humans and rodents the adult spinal cord harbors neural stem cells located around the central canal. Their identity, precise location, and specific signaling are still ill-defined and controversial. We report here on a detailed analysis of this niche. Using microdissection and glial fibrillary acidic protein (GFAP)-green fluorescent protein (GFP) transgenic mice, we demonstrate that neural stem cells are mostly dorsally located GFAP(+) cells lying ependymally and subependymally that extend radial processes toward the pial surface. The niche also harbors doublecortin protein (Dcx)(+) Nkx6.1(+) neurons sending processes into the lumen. Cervical and lumbar spinal cord neural stem cells maintain expression of specific rostro-caudal Hox gene combinations and the niche shows high levels of signaling proteins (CD15, Jagged1, Hes1, differential screening-selected gene aberrative in neuroblastoma [DAN]). More surprisingly, the niche displays mesenchymal traits such as expression of epithelial-mesenchymal-transition zinc finger E-box-binding protein 1 (ZEB1) transcription factor and smooth muscle actin. We found ZEB1 to be essential for neural stem cell survival in vitro. Proliferation within the niche progressively ceases around 13 weeks when the spinal cord reaches its final size, suggesting an active role in postnatal development. In addition to hippocampus and subventricular zone niches, adult spinal cord constitutes a third central nervous system stem cell niche with specific signaling, cellular, and structural characteristics that could possibly be manipulated to alleviate spinal cord traumatic and degenerative diseases.

  4. Suppression of spinal connexin 43 expression attenuates mechanical hypersensitivity in rats after an L5 spinal nerve injury.

    PubMed

    Xu, Qian; Cheong, Yong-Kwan; He, Shao-Qiu; Tiwari, Vinod; Liu, Jian; Wang, Yun; Raja, Srinivasa N; Li, Jinheng; Guan, Yun; Li, Weiyan

    2014-04-30

    Activation of spinal astrocytes may contribute to neuropathic pain. Adjacent astrocytes can make direct communication through gap junctions formed by connexin 43 (Cx43) in the central nervous system. Yet, the role of spinal astroglial gap junctions in neuropathic pain is not fully understood. Since Cx43 is the connexin isoform expressed preferentially in astrocytes in the spinal cord, we used a small interfering RNA (siRNA) approach to examine whether suppression of spinal Cx43 expression inhibits mechanical hypersensitivity in rats after an L5 spinal nerve ligation (SNL). SNL rats were administered intrathecal Cx43 siRNA (3μg/15μl, twice/day) or an equal amount of mismatch siRNA (control) on days 14-17 post-SNL. Cx43 siRNA, but not mismatch siRNA, alleviated mechanical hypersensitivity in SNL rats. Furthermore, Western blot analysis showed that the pain inhibition induced by Cx43 siRNA correlated with downregulation of Cx43 expression, but not that of Cx36 (the neuronal gap junction protein) or glial fibrillary acidic protein (GFAP, a marker for reactive astrocytes) in the spinal cord of SNL rats. Western blot analysis and immunohistochemistry also showed that SNL increased GFAP expression, but decreased Cx43 expression, in spinal cord. Our results provide direct evidence that selective suppression of spinal Cx43 after nerve injury alleviates neuropathic mechanical hypersensitivity. These findings suggest that in the spinal cord, the enhanced function of astroglial gap junctions, especially those formed by Cx43, may be important to neuropathic pain in SNL rats.

  5. BDNF regulation in the rat dorsal vagal complex during stress-induced anorexia.

    PubMed

    Charrier, Céline; Chigr, Fatiha; Tardivel, Catherine; Mahaut, Stéphanie; Jean, André; Najimi, Mohamed; Moyse, Emmanuel

    2006-08-30

    The dorsal vagal complex (DVC) is the satiety reflex-integrating center of adult mammals. Immobilization stress (IS) is known to elicit anorexia and to up-regulate BDNF expression in adult rat forebrain; intra-DVC delivery of BDNF was shown to elicit anorexia. Therefore, we addressed here whether IS would increase BDNF signaling in rat DVC by using PCR and western-blot on microdissected tissue extracts. Significant variations of BDNF expression in DVC after IS include exon V mRNA increase at 3 h, decreases of both protein and exon III mRNA at 24 h, and exon I mRNA decrease at 72 h. At the receptor level, IS elicited a highly significant induction of both full-length and truncated-1 TrkB mRNAs at 24 h after IS. In vivo recruitment of BDNF signaling in DVC during stress thus differs from hypothalamus, the relevance of which to anorexia is discussed.

  6. 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.

  7. 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

  8. Intrathecal Acetyl-L-Carnitine Protects Tissue and Improves Function after a Mild Contusive Spinal Cord Injury in Rats.

    PubMed

    Ewan, Eric E; Hagg, Theo

    2016-02-01

    Primary and secondary ischemia after spinal cord injury (SCI) contributes to tissue and axon degeneration, which may result from decreased energy substrate availability for cellular and axonal mitochondrial adenosine triphosphate (ATP) production. Therefore, providing spinal tissue with an alternative energy substrate during ischemia may be neuroprotective after SCI. To assess this, rats received a mild contusive SCI (120 kdyn, Infinite Horizons impactor) at thoracic level 9 (T9), which causes loss of ∼ 80% of the ascending sensory dorsal column axonal projections to the gracile nucleus. Immediately afterwards, the energy substrate acetyl-L-carnitine (ALC; 1 mg/day) or phosphate-buffered saline (PBS) was infused intrathecally (sub-arachnoid) for 6 days via an L5/6 catheter attached to a subcutaneous Alzet pump. ALC treatment improved overground locomotor function (Basso-Beattie-Breshnahan [BBB] score 18 vs. 13) at 6 days, total spared epicenter (71% vs. 57%) and penumbra white matter (90% vs. 85%), ventral penumbra microvessels (108% vs. 79%), and penumbra motor neurons (42% vs. 15%) at 15 days post-SCI, compared with PBS treatment. However, the ascending sensory projections (anterogradely traced with cholera toxin B from the sciatic nerves) and dorsal column white matter and perfused blood vessels were not protected. Furthermore, grid walking, a task we have shown to be dependent on dorsal column function, was not improved. Thus, mitochondrial substrate replacement may only be efficacious in areas of lesser or temporary ischemia, such as the ventral spinal cord and injury penumbra in this study. The current data also support our previous evidence that microvessel loss is central to secondary tissue degeneration.

  9. Intrathecal Acetyl-l-Carnitine Protects Tissue and Improves Function after a Mild Contusive Spinal Cord Injury in Rats

    PubMed Central

    Ewan, Eric E.

    2016-01-01

    Abstract Primary and secondary ischemia after spinal cord injury (SCI) contributes to tissue and axon degeneration, which may result from decreased energy substrate availability for cellular and axonal mitochondrial adenosine triphosphate (ATP) production. Therefore, providing spinal tissue with an alternative energy substrate during ischemia may be neuroprotective after SCI. To assess this, rats received a mild contusive SCI (120 kdyn, Infinite Horizons impactor) at thoracic level 9 (T9), which causes loss of ∼80% of the ascending sensory dorsal column axonal projections to the gracile nucleus. Immediately afterwards, the energy substrate acetyl-l-carnitine (ALC; 1 mg/day) or phosphate-buffered saline (PBS) was infused intrathecally (sub-arachnoid) for 6 days via an L5/6 catheter attached to a subcutaneous Alzet pump. ALC treatment improved overground locomotor function (Basso-Beattie-Breshnahan [BBB] score 18 vs. 13) at 6 days, total spared epicenter (71% vs. 57%) and penumbra white matter (90% vs. 85%), ventral penumbra microvessels (108% vs. 79%), and penumbra motor neurons (42% vs. 15%) at 15 days post-SCI, compared with PBS treatment. However, the ascending sensory projections (anterogradely traced with cholera toxin B from the sciatic nerves) and dorsal column white matter and perfused blood vessels were not protected. Furthermore, grid walking, a task we have shown to be dependent on dorsal column function, was not improved. Thus, mitochondrial substrate replacement may only be efficacious in areas of lesser or temporary ischemia, such as the ventral spinal cord and injury penumbra in this study. The current data also support our previous evidence that microvessel loss is central to secondary tissue degeneration. PMID:26415041

  10. Delayed activation of spinal microglia contributes to the maintenance of bone cancer pain in female Wistar rats via P2X7 receptor and IL-18.

    PubMed

    Yang, Yan; Li, Hui; Li, Ting-Ting; Luo, Hao; Gu, Xi-Yao; Lü, Ning; Ji, Ru-Rong; Zhang, Yu-Qiu

    2015-05-20

    Accumulating evidence suggests that activation of spinal microglia contributes to the development of inflammatory and neuropathic pain. However, the role of spinal microglia in the maintenance of chronic pain remains controversial. Bone cancer pain shares features of inflammatory and neuropathic pain, but the temporal activation of microglia and astrocytes in this model is not well defined. Here, we report an unconventional role of spinal microglia in the maintenance of advanced-phase bone cancer pain in a female rat model. Bone cancer elicited delayed and persistent microglial activation in the spinal dorsal horn on days 14 and 21, but not on day 7. In contrast, bone cancer induced rapid and persistent astrocytic activation on days 7-21. Spinal inhibition of microglia by minocycline at 14 d effectively reduced bone cancer-induced allodynia and hyperalgesia. However, pretreatment of minocycline in the first week did not affect the development of cancer pain. Bone cancer increased ATP levels in CSF, and upregulated P2X7 receptor, phosphorylated p38, and IL-18 in spinal microglia. Spinal inhibition of P2X7/p-38/IL-18 pathway reduced advanced-phase bone cancer pain and suppressed hyperactivity of spinal wide dynamic range (WDR) neurons. IL-18 induced allodynia and hyperalgesia after intrathecal injection, elicited mechanical hyperactivity of WDR neurons in vivo, and increased the frequency of mEPSCs in spinal lamina IIo nociceptive synapses in spinal cord slices. Together, our findings demonstrate a novel role of microglia in maintaining advanced phase cancer pain in females via producing the proinflammatory cytokine IL-18 to enhance synaptic transmission of spinal cord nociceptive neurons.

  11. Neurotoxic Doses of Chronic Methamphetamine Trigger Retrotransposition of the Identifier Element in Rat Dorsal Dentate Gyrus

    PubMed Central

    Moszczynska, Anna; Burghardt, Kyle J.; Yu, Dongyue

    2017-01-01

    Short interspersed elements (SINEs) are typically silenced by DNA hypermethylation in somatic cells, but can retrotranspose in proliferating cells during adult neurogenesis. Hypomethylation caused by disease pathology or genotoxic stress leads to genomic instability of SINEs. The goal of the present investigation was to determine whether neurotoxic doses of binge or chronic methamphetamine (METH) trigger retrotransposition of the identifier (ID) element, a member of the rat SINE family, in the dentate gyrus genomic DNA. Adult male Sprague-Dawley rats were treated with saline or high doses of binge or chronic METH and sacrificed at three different time points thereafter. DNA methylation analysis, immunohistochemistry and next-generation sequencing (NGS) were performed on the dorsal dentate gyrus samples. Binge METH triggered hypomethylation, while chronic METH triggered hypermethylation of the CpG-2 site. Both METH regimens were associated with increased intensities in poly(A)-binding protein 1 (PABP1, a SINE regulatory protein)-like immunohistochemical staining in the dentate gyrus. The amplification of several ID element sequences was significantly higher in the chronic METH group than in the control group a week after METH, and they mapped to genes coding for proteins regulating cell growth and proliferation, transcription, protein function as well as for a variety of transporters. The results suggest that chronic METH induces ID element retrotransposition in the dorsal dentate gyrus and may affect hippocampal neurogenesis. PMID:28272323

  12. Inhibition of calcium currents in cultured rat dorsal root ganglion neurones by (-)-baclofen.

    PubMed Central

    Dolphin, A. C.; Scott, R. H.

    1986-01-01

    Voltage-dependent inward calcium currents (ICa) activated in cultured rat dorsal root ganglion neurones were reversibly reduced in a dose-dependent manner by (-)-baclofen (10 microM to 100 microM). Baclofen (100 microM) reduced the calcium-dependent slow outward potassium current (IK(Ca)). This current was abolished in calcium-free medium and by 300 microM cadmium chloride. The action of baclofen on IK(Ca) was reduced when the calcium concentration in the medium was increased from 5 mM to 30 mM. The calcium independent fast transient voltage-dependent outward current (IK(Vt] was also reduced by baclofen; this effect remained present when Ca2+-free medium was used to prevent contamination by IK(Ca). 4-Aminopyridine (500 microM) reduced IK(Vt) and induced a small increase in ICa. The action of baclofen on ICa was partially antagonized by 4-aminopyridine. GABAB receptor-mediated inhibition of ICa in cultured rat dorsal root ganglion neurones involves a direct mechanism rather than resulting indirectly from an increase in the residual outward potassium currents activated by depolarization. The reduction in ICa by baclofen was variable and dependent on the amplitude of control ICa, larger currents being more resistant to the baclofen-induced inhibition. PMID:2423173

  13. 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

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

    PubMed

    Qu, Yu-Juan; Jia, Lei; Zhang, Xiao; Wei, Hui; Yue, Shou-Wei

    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.

  15. 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.

  16. Chronic morphine treatment enhances sciatic nerve stimulation-induced immediate early gene expression in the rat dorsal horn.

    PubMed

    Bojovic, Ognjen; Bramham, Clive R; Tjølsen, Arne

    2015-01-01

    Synaptic plasticity is a property of neurons that can be induced by conditioning electrical stimulation (CS) of afferent fibers in the spinal cord. This is a widely studied property of spinal cord and hippocampal neurons. CS has been shown to trigger enhanced expression of immediate early gene proteins (IEGPs), with peak increases observed 2 hour post stimulation. Chronic morphine treatment has been shown to promoteinduce opioid-induced hyperalgesia, and also to increase CS-induced central sensitization in the dorsal horn. As IEGP expression may contribute to development of chronic pain states, we aimed to determine whether chronic morphine treatment affects the expression of IEGPs following sciatic nerve CS. Changes in expression of the IEGPs Arc, c-Fos or Zif268 were determined in cells of the lumbar dorsal horn of the spinal cord. Chronic Morphine pretreatment over 7 days led to a significant increase in the number of IEGP positive cells observed at both 2 h and 6 h after CS. The same pattern of immunoreactivity was obtained for all IEGPs, with peak increases occurring at 2 h post CS. In contrast, morphine treatment alone in sham operated animals had no effect on IEGP expression. We conclude that chronic morphine treatment enhances stimulus-induced expression of IEGPs in the lumbar dorsal horn. These data support the notion that morphine alters gene expression responses linked to nociceptive stimulation and plasticity.

  17. Neuropathic pain modifies antioxidant activity in rat spinal cord.

    PubMed

    Guedes, Renata P; Bosco, Lidiane Dal; Teixeira, Camila M; Araújo, Alex S R; Llesuy, Susana; Belló-Klein, Adriane; Ribeiro, Maria Flávia M; Partata, Wania A

    2006-05-01

    Oxidative stress is an important pathophysiological mechanism of many neurological diseases. Reactive oxygen and nitrogen species have been cited as molecules involved in the nociceptive process. In this study, rats were submitted to sciatic nerve transection (SNT) for induction of neuropathic pain, and enzyme activities of SOD and catalase as well as lipid peroxidation (LPO) were measured in the lumbosacral spinal cord. The results show that LPO was not changed after SNT. SOD activity was reduced 7 days after SNT, while the change in catalase activity occurred on the third and seventh days in both sham and SNT animals. Hyperalgesia in SNT group was detected at the same points in time. These results suggest that SNT was not a strong enough stimulus to deplete all antioxidant content in the spinal cord, since increase in LPO was not detected. However, the role of oxidative stress in nociception can not be excluded.

  18. A non-pungent triprenyl phenol of fungal origin, scutigeral, stimulates rat dorsal root ganglion neurons via interaction at vanilloid receptors.

    PubMed

    Szallasi, A; Bíró, T; Szabó, T; Modarres, S; Petersen, M; Klusch, A; Blumberg, P M; Krause, J E; Sterner, O

    1999-03-01

    1. A [3H]-resiniferatoxin (RTX) binding assay utilizing rat spinal cord membranes was employed to identify novel vanilloids in a collection of natural products of fungal origin. Of the five active compounds found (scutigeral, acetyl-scutigeral, ovinal, neogrifolin, and methyl-neogrifolin), scutigeral (Ki=19 microM), isolated from the edible mushroom Albatrellus ovinus, was selected for further characterization. 2. Scutigeral induced a dose-dependent 45Ca uptake by rat dorsal root ganglion neurons with an EC50 of 1.6 microM, which was fully inhibited by the competitive vanilloid receptor antagonist capsazepine (IC50=5.2 microM). 3. [3H]-RTX binding isotherms were shifted by scutigeral (10-80 microM) in a competitive manner. The Schild plot of the data had a slope of 0.8 and gave an apparent Kd estimate for scutigeral of 32 microM. 4. Although in the above assays scutigeral mimicked capsaicin, it was not pungent on the human tongue up to a dose of 100 nmol per tongue, nor did it provoke protective wiping movements in the rat (up to 100 microM) upon intraocular instillation. 5. In accord with being non-pungent, scutigeral (5 microM) did not elicit a measurable inward current in isolated rat dorsal root ganglion neurons under voltage-clamp conditions. It did, however, reduce the proportion of neurons (from 61 to 15%) that responded to a subsequent capsaicin (1 microM) challenge. In these neurons, scutigeral both delayed (from 27 to 72 s) and diminished (from 5.0 to 1.9 nA) the maximal current evoked by capsaicin. 6. In conclusion, scutigeral and its congeners form a new chemical class of vanilloids, the triprenyl phenols. Scutigeral promises to be a novel chemical lead for the development of orally active, non-pungent vanilloids.

  19. [Experimental syringomyelia in rabbits and rats after localized spinal arachnoiditis].

    PubMed

    Tatara, N

    1992-12-01

    In order to produce syringomyelia, localized arachnoiditis was created in adult New Zealand albino rabbits and Wistar rats by the injection of kaolin into the thoracic spinal subarachnoid space and incision of the dura mater of the thoracic spinal cord. The rabbits and rats were divided into 3 groups; the control group, dural incision group (DG) and kaolin injection group (KG). Each rabbit was sacrificed at 4, 8, 12 and 16 weeks after the operation. Each rat was sacrificed at 8 and 16 weeks after the operation. Cavity formation in the cord of all rabbits was examined by ultrasound. All animals were perfused with 10% neutral beffered formalin at 150 cm H2O pressure, and histological examination was performed with Luxol fast blue (LFB) and hematoxylin and eosin (H&E) stains. Results obtained: (1) Cavity formation was noted in 6 of 16 DG of rabbit (37.5%), 5 of 16 KG of rabbit (31.2%) and 2 of 9 KG of rat (22.2%) with histological verification. With use of ultrasound, cavity was noted in 3 of 16 DG rabbits (12.5%) and 2 of 16 KG rabbits (18.8%). (2) Cavity formation was present in the cord adjacent to the marked adhesive arachnoiditis both in rabbits and in rats. (3) Cavity was noted in the ischemic area. (4) In 2 rabbits in which kaolin encircled whole surface of the spinal cord, hydromyelia was formed communicating with enlarged central canal caudad from the kaolin subarachnoid block. (5) Histological examination showed obliteration or narrowing of lumen of the small pial vessels involved in the adhesive arachnoiditis. In the cord parenchyma adjacent to the arachnoiditis, multiple spots of demyelination due secondary to ischemia demonstrated by LFB stain were noted. On the other hand, in the cord with the pia-arachnoid remained uninvolved, no demyelination was observed. (6) Localized adhesive arachnoiditis consisted of proliferation of fibrous tissue, lymphocytic infiltration and obliterating processes of small pial vessels involved in it. These data suggest that

  20. 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.

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

    PubMed Central

    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.

    2016-01-01

    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

  2. BDNF promotes connections of corticospinal neurons onto spared descending interneurons in spinal cord injured rats.

    PubMed

    Vavrek, R; Girgis, J; Tetzlaff, W; Hiebert, G W; Fouad, K

    2006-06-01

    Although regeneration of injured axons is inhibited within the adult CNS, moderate recovery can be found in patients and animals with incomplete spinal cord injury (SCI). This can be partly attributed to sprouting of spared and injured axons, rostral and caudal to the lesion, respectively. Recently, it has been reported that following a thoracic SCI such sprouting can result in indirect reconnections of the lesioned axons to caudal targets via propriospinal interneurons (PrI). Here, we attempted to further promote this spontaneous repair mechanism by applying the neurotrophic factor BDNF (brain-derived neurotrophic factor), in the vicinity of the cell bodies of lesioned corticospinal neurons or NT-3, intrathecally to the cervical spinal cord. We performed a dorsal over-hemisection at the thoracic spinal cord sparing only the left ventrolateral quadrant. This type of lesion did not promote sprouting of injured corticospinal axons or re-routing via commissural PrI. Also, in rats that received NT-3 at the cervical enlargement, no increase in sprouting was found. However, animals receiving BDNF at the cell bodies of lesioned corticospinal neurons showed a significant increase in collateral sprouting and in the number of contacts with PrI. This was not observed when BDNF was administered to unlesioned animals. Although no statistical difference in the horizontal ladder walking was found between the groups, the increase in collateral sprouting and in the number of contacts correlated with the functional recovery. Hence, cell body treatment can promote plasticity of the injured CNS and may be a valuable treatment approach in conjunction with local regeneration promoting strategies.

  3. Spinal administration of a delta opioid receptor agonist attenuates hyperalgesia and allodynia in a rat model of neuropathic pain.

    PubMed

    Holdridge, Sarah V; Cahill, Catherine M

    2007-08-01

    Neuropathic (NP) pain is a debilitating chronic pain disorder considered by some to be inherently resistant to therapy with traditional analgesics. Indeed, micro opioid receptor (OR) agonists show reduced therapeutic benefit and their long term use is hindered by the high incidence of adverse effects. However, pharmacological and physiological evidence increasingly suggests a role for deltaOR agonists in modulating NP pain symptoms. In this study, we examined the antihyperalgesic and antiallodynic effects of the spinally administered deltaOR agonist, d-[Ala(2), Glu(4)]deltorphin II (deltorphin II), as well as the changes in deltaOR expression, in rats following chronic constriction injury (CCI) of the sciatic nerve. Rats with CCI exhibited cold hyperalgesia and mechanical allodynia over a 14-day testing period. Intrathecal administration of deltorphin II reversed cold hyperalgesia on day 14 and dose-dependently attenuated mechanical allodynia. The effects of deltorphin II were mediated via activation of the deltaOR as the effect was antagonized by co-treatment with the delta-selective antagonist, naltrindole. Western blotting experiments revealed no changes in deltaOR protein in the dorsal spinal cord following CCI. Taken together, these data demonstrate the antihyperalgesic and antiallodynic effectiveness of a spinally administered deltaOR agonist following peripheral nerve injury and support further investigation of deltaORs as potential therapeutic targets in the treatment of NP pain.

  4. 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.

  5. The effects of gallamine on field and dorsal root potentials produced by antidromic stimulation of motor fibres in the frog spinal cord.

    PubMed

    Galindo, J; Rudomin, P

    1978-05-12

    The effects of gallamine on the intraspinal field potentials and the dorsal root potentials produced by antidromic stimulation of motor fibres were studied in the isolated frog spinal cord preparation. After gallamine (10-(3) M), the duration of the negative field potential produced by antidromic activation of motoneurons (N1 response) was increased often without changing its amplitude. This resulted in an increased passive spread of the antidromic action potential towards the dorsal dendritic regions, where afferent fibres terminate. In the untreated spinal cord, stimulation of motor axons produced a late negative dorsal root potential (VR-DRP) which was depressed after gallamine administration. Abolition of the VR-DRP was frequently associated with the appearance of a short latency, conducted response, in the dorsal roots (EVR-DRP). The earliest component of the EVR-DRP had a latency ranging between 0.5 and 2.5 ms measured after the peak of the N1 response recorded at the motor nucleus. Such a brief latency of the EVR-DRP suggests that this response results from electrical interaction between motoneurons and afferent fibres. After gallamine, the primary afferent depolarization produced by orthodromic stimulation of sensory nerves facilitates the EVR-DRP without necessarily increasing the amplitude or duration of the N1 response. Also, gallamine appears to increase directly the excitability of the afferent fibre terminal arborizations. The nature of the electrical interaction between motoneuron dendrites and afferent fibre terminal arborizations is discussed in terms of two hypotheses: interaction by current flows and by electrical coupling.

  6. 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

  7. Glycine transporter GlyT1, but not GlyT2, is expressed in rat dorsal root ganglion--Possible implications for neuropathic pain.

    PubMed

    Schlösser, Lukas; Barthel, Franziska; Brandenburger, Timo; Neumann, Elena; Bauer, Inge; Eulenburg, Volker; Werdehausen, Robert; Hermanns, Henning

    2015-07-23

    Glycinergic inhibitory neurotransmission plays a pivotal role in the development of neuropathic pain. The glycine concentration in the synaptic cleft is controlled by the glycine transporters GlyT1 and GlyT2. GlyT1 is expressed throughout the central nervous system, while GlyT2 is exclusively located in glycinergic neurons. Aim of the present study was to investigate whether GlyTs are also expressed in the peripheral sensory nervous system and whether their expression is modulated in experimental neuropathic pain. Neuropathic pain was induced in male Wistar rats by Chronic Constriction Injury (CCI) and verified by assessment of mechanical allodynia (von Frey method). Expression patterns of GlyTs and the glycine binding subunit NR1 of the N-methyl-d-aspartate (NMDA) receptor in the spinal cord and dorsal root ganglia (DRG) were analyzed by Western blot analysis, PCR and immunohistochemistry. While both GlyT1 and GlyT2 were detected in the spinal cord, only GlyT1, but not GlyT2, was detected in DRG. Immunofluorescence revealed a strictly neuronal localization of GlyT1 and a co-localization of GlyT1 and NR1 in DRG. Compared to sham procedure, spinal cord and DRG expression of GlyT1 was not altered and NR1 was unchanged in DRG 12 days after CCI. GlyT1, but not GlyT2, is expressed in the peripheral sensory nervous system. The co-expression of GlyT1 and NMDA receptors in DRG suggests that GlyT1 regulates glycine concentration at the glycine binding site of the NMDA receptor. Differential regulation of GlyT1 expression in the spinal cord or DRG, however, does not seem to be associated with the development of neuropathic pain.

  8. 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.

  9. Epidural Stimulation Induced Modulation of Spinal Locomotor Networks in Adult Spinal Rats

    PubMed Central

    Lavrov, Igor; Dy, Christine J.; Fong, Andy J.; Gerasimenko, Yury; Courtine, Grégoire; Zhong, Hui; Roy, Roland R.; Edgerton, V. Reggie

    2010-01-01

    The importance of the in vivo dynamic nature of the circuitries within the spinal cord that generate locomotion is becoming increasingly evident. We examined the characteristics of hindlimb EMG activity evoked in response to epidural stimulation at the S1 spinal cord segment in complete mid-thoracic spinal cord transected rats at different stages of post-lesion recovery. A progressive and phase-dependent modulation of monosynaptic (middle) and long latency (late) stimulation-evoked EMG responses was observed throughout the step cycle. During the first three weeks after injury the amplitude of the middle response was potentiated during the EMG bursts, whereas after 4 weeks both the middle and late responses were phase-dependently modulated. The middle and late response magnitudes were closely linked to the amplitude and duration of the EMG bursts during locomotion facilitated by epidural stimulation. The optimum stimulation frequency that maintained consistent activity of the long latency responses ranged from 40 to 60 Hz, whereas the short latency responses were consistent from 5 to 130 Hz. These data demonstrate that both middle and late evoked potentials within a motor pool are strictly gated during in vivo bipedal stepping as a function of the general excitability of the motor pool and, thus as a function of the phase of the step cycle. These data demonstrate that spinal cord epidural stimulation can facilitate locomotion in a time-dependent manner post-lesion. The long latency responses to epidural stimulation are correlated with the recovery of weight-bearing bipedal locomotion and may reflect activation of interneuronal central pattern-generating circuits. PMID:18524907

  10. Epidural stimulation induced modulation of spinal locomotor networks in adult spinal rats.

    PubMed

    Lavrov, Igor; Dy, Christine J; Fong, Andy J; Gerasimenko, Yury; Courtine, Grégoire; Zhong, Hui; Roy, Roland R; Edgerton, V Reggie

    2008-06-04

    The importance of the in vivo dynamic nature of the circuitries within the spinal cord that generate locomotion is becoming increasingly evident. We examined the characteristics of hindlimb EMG activity evoked in response to epidural stimulation at the S1 spinal cord segment in complete midthoracic spinal cord-transected rats at different stages of postlesion recovery. A progressive and phase-dependent modulation of monosynaptic (middle) and long-latency (late) stimulation-evoked EMG responses was observed throughout the step cycle. During the first 3 weeks after injury, the amplitude of the middle response was potentiated during the EMG bursts, whereas after 4 weeks, both the middle and late responses were phase-dependently modulated. The middle- and late-response magnitudes were closely linked to the amplitude and duration of the EMG bursts during locomotion facilitated by epidural stimulation. The optimum stimulation frequency that maintained consistent activity of the long-latency responses ranged from 40 to 60 Hz, whereas the short-latency responses were consistent from 5 to 130 Hz. These data demonstrate that both middle and late evoked potentials within a motor pool are strictly gated during in vivo bipedal stepping as a function of the general excitability of the motor pool and, thus, as a function of the phase of the step cycle. These data demonstrate that spinal cord epidural stimulation can facilitate locomotion in a time-dependent manner after lesion. The long-latency responses to epidural stimulation are correlated with the recovery of weight-bearing bipedal locomotion and may reflect activation of interneuronal central pattern-generating circuits.

  11. Alleviation of chronic pain following rat spinal cord compression injury with multimodal actions of huperzine A

    PubMed Central

    Yu, Dou; Thakor, Devang K.; Han, Inbo; Ropper, Alexander E.; Haragopal, Hariprakash; Sidman, Richard L.; Zafonte, Ross; Schachter, Steven C.; Teng, Yang D.

    2013-01-01

    Diverse mechanisms including activation of NMDA receptors, microglial activation, reactive astrogliosis, loss of descending inhibition, and spasticity are responsible for ∼40% of cases of intractable neuropathic pain after spinal cord injury (SCI). Because conventional treatments blocking individual mechanisms elicit only short-term effectiveness, a multimodal approach with simultaneous actions against major pain-related pathways may have value for clinical management of chronic pain. We hypothesize that [-]-huperzine A (HUP-A), an alkaloid isolated from the club moss Huperzia serrata, that is a potent reversible inhibitor of acetylcholinesterase and NMDA receptors, could mitigate pain without invoking drug tolerance or dependence by stimulating cholinergic interneurons to impede pain signaling, inhibiting inflammation via microglial cholinergic activation, and blocking NMDA-mediated central hypersensitization. We tested our hypothesis by administering HUP-A i.p. or intrathecally to female Sprague–Dawley rats (200–235 g body weight) after moderate static compression (35 g for 5 min) of T10 spinal cord. Compared with controls, HUP-A treatment demonstrates significant analgesic effects in both regimens. SCI rats manifested no drug tolerance following repeated bolus i.p. or chronic intrathecal HUP-A dosing. The pain-ameliorating effect of HUP-A is cholinergic dependent. Relative to vehicle treatment, HUP-A administration also reduced neural inflammation, retained higher numbers of calcium-impermeable GluR2-containing AMPA receptors, and prevented Homer1a up-regulation in dorsal horn sensory neurons. Therefore, HUP-A may provide safe and effective management for chronic postneurotrauma pain by reestablishing homeostasis of sensory circuits. PMID:23386718

  12. Glycine receptor heterogeneity in rat spinal cord during postnatal development.

    PubMed Central

    Becker, C M; Hoch, W; Betz, H

    1988-01-01

    Two different isoforms of the inhibitory glycine receptor were identified during postnatal development of rat spinal cord. A neonatal form characterized by low strychnine binding affinity, altered antigenicity, and a ligand binding subunit differing in mol. wt (49 kd) from that of the adult receptor (48 kd) predominates at birth (70% of the total receptor protein). Separation from the adult form could be achieved by either use of a selective antibody or glycine gradient elution of 2-aminostrychnine affinity columns. Both isoforms co-purify with the mol. wt 93 kd peripheral membrane protein of the postsynaptic glycine receptor complex. Images PMID:2850172

  13. Early radiation-induced endothelial cell loss and blood-spinal cord barrier breakdown in the rat spinal cord.

    PubMed

    Li, Yu-Qing; Chen, Paul; Jain, Vipan; Reilly, Raymond M; Wong, C Shun

    2004-02-01

    Using a rat spinal cord model, this study was designed to characterize radiation-induced vascular endothelial cell loss and its relationship to early blood-brain barrier disruption in the central nervous system. Adult rats were given a single dose of 0, 2, 8, 19.5, 22, 30 or 50 Gy to the cervical spinal cord. At various times up to 2 weeks after irradiation, the spinal cord was processed for histological and immunohistochemical analysis. Radiation-induced apoptosis was assessed by morphology and TdT-mediated dUTP nick end labeling combined with immunohistochemical markers for endothelial and glial cells. Image analysis was performed to determine endothelial cell and microvessel density using immunohistochemistry with endothelial markers, namely endothelial barrier antigen, glucose transporter isoform 1, laminin and zonula occludens 1. Blood-spinal cord barrier permeability was assessed using immunohistochemistry for albumin and (99m)Tc-diethylenetriamine pentaacetic acid as a vascular tracer. Endothelial cell proliferation was assessed using in vivo BrdU labeling. During the first 24 h after irradiation, apoptotic endothelial cells were observed in the rat spinal cord. The decrease in endothelial cell density at 24 h after irradiation was associated with an increase in albumin immunostaining around microvessels. The decrease in the number of endothelial cells persisted for 7 days and recovery of endothelial density was apparent by day 14. A similar pattern of blood-spinal cord barrier disruption and recovery of permeability was observed over the 2 weeks, and an increase in BrdU-labeled endothelial cells was seen at day 3. These results are consistent with an association between endothelial cell death and acute blood-spinal cord barrier disruption in the rat spinal cord after irradiation.

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

    PubMed Central

    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

  15. Cholinergic modulation of primary afferent glutamatergic transmission in rat medullary dorsal horn neurons.

    PubMed

    Jeong, Seok-Gwon; Choi, In-Sun; Cho, Jin-Hwa; Jang, Il-Sung

    2013-12-01

    Although muscarinic acetylcholine (mACh) receptors are expressed in trigeminal ganglia, it is still unknown whether mACh receptors modulate glutamatergic transmission from primary afferents onto medullary dorsal horn neurons. In this study, we have addressed the cholinergic modulation of primary afferent glutamatergic transmission using a conventional whole cell patch clamp technique. Glutamatergic excitatory postsynaptic currents (EPSCs) were evoked from primary afferents by electrical stimulation of trigeminal tract and monosynaptic EPSCs were recorded from medullary dorsal horn neurons of rat horizontal brain stem slices. Muscarine and ACh reversibly and concentration-dependently decreased the amplitude of glutamatergic EPSCs and increased the paired-pulse ratio. In addition, muscarine reduced the frequency of miniature EPSCs without affecting the current amplitude, suggesting that muscarine acts presynaptically to decrease the probability of glutamate release onto medullary dorsal horn neurons. The muscarine-induced decrease of glutamatergic EPSCs was significantly occluded by methoctramine or AF-DX116, M2 receptor antagonists, but not pirenzepine, J104129 and MT-3, selective M1, M3 and M4 receptor antagonists. The muscarine-induced decrease of glutamatergic EPSCs was highly dependent on the extracellular Ca2+ concentration. Physostigmine and clinically available acetylcholinesterase inhibitors, such as rivastigmine and donepezil, significantly shifted the concentration-inhibition relationship of ACh for glutamatergic EPSCs. These results suggest that muscarine acts on presynaptic M2 receptors to inhibit glutamatergic transmission by reducing the Ca2+ influx into primary afferent terminals, and that M2 receptor agonists and acetylcholinesterase inhibitors could be, at least, potential targets to reduce nociceptive transmission from orofacial tissues.

  16. Spinal cord projections of the rat main forelimb nerves, studied by transganglionic transport of WGA-HRP and by the disappearance of acid phosphatase.

    PubMed

    Castro-Lopes, J M; Coimbra, A

    1991-03-01

    The spinal cord projections of the 3 main forelimb nerves-median, radial and ulnar, were studied in the rat dorsal horn with transganglionic transport of wheat germ agglutinin-horseradish peroxidase (WGA-HRP), or using the disappearance of fluoride resistant acid phosphatase (FRAP) after nerve section. The projection patterns in lamina II were similar following the two procedures. The median and the radial nerve fibers projected to the medial and the intermediate thirds, respectively, of the dorsal horn lamina II in spinal cord segments C4-C8. The ulnar nerve projected to segments C6-C8 between the areas occupied by the other two nerves. The FRAP method also showed that the lateral part of lamina II, which was not filled by radial nerve fibers, received the projections from the dorsal cutaneous branches of cervical spinal nerves. In addition, FRAP disappeared from the medial end of segment T1 after skin incisions extending from the medial brachium to the axilla, which seemed due to severance of the cutaneous branchlets of the lateral anterior thoracic nerve. The FRAP procedure is thus sensitive enough to detect fibers in lamina II arising from small peripheral nerves, and may be used as an alternative to the anterograde tracing methods whenever there are no overlapping projections.

  17. Endomorphin-2 Inhibition of Substance P Signaling within Lamina I of the Spinal Cord Is Impaired in Diabetic Neuropathic Pain Rats

    PubMed Central

    Wan, Fa-Ping; Bai, Yang; Kou, Zhen-Zhen; Zhang, Ting; Li, Hui; Wang, Ya-Yun; Li, Yun-Qing

    2017-01-01

    Opiate analgesia in the spinal cord is impaired in diabetic neuropathic pain (DNP), but until now the reason is unknown. We hypothesized that it resulted from a decreased inhibition of substance P (SP) signaling within the dorsal horn of the spinal cord. To investigate this possibility, we evaluated the effects of endomorphin-2 (EM2), an endogenous ligand of the μ-opioid receptor (MOR), on SP release within lamina I of the spinal dorsal horn (SDH) in rats with DNP. We established the DNP rat model and compared the analgesic efficacy of EM2 between inflammation pain and DNP rat models. Behavioral results suggested that the analgesic efficacy of EM2 was compromised in the condition of painful diabetic neuropathy. Then, we measured presynaptic SP release induced by different stimulating modalities via neurokinin-1 receptor (NK1R) internalization. Although there was no significant change in basal and evoked SP release between control and DNP rats, EM2 failed to inhibit SP release by noxious mechanical and thermal stimuli in DNP but not in control and inflammation pain model. We also observed that EM2 decreased the number of FOS-positive neurons within lamina I of the SDH but did not change the amount of FOS/NK1R double-labeled neurons. Finally, we identified a remarkable decrease in MORs within the primary afferent fibers and dorsal root ganglion (DRG) neurons by Western blot (WB) and immunohistochemistry (IHC). Taken together, these data suggest that reduced presynaptic MOR expression might account for the loss of the inhibitory effect of EM2 on SP signaling, which might be one of the neurobiological foundations for decreased opioid efficacy in the treatment of DNP. PMID:28119567

  18. Differences in spinal distribution and neurochemical phenotype of colonic afferents in mouse and rat.

    PubMed

    Christianson, Julie A; Traub, Richard J; Davis, Brian M

    2006-01-10

    Visceral pain is a prevalent clinical problem and one of the most common ailments for which patients seek medical attention. Recent studies have described many of the physiological properties of visceral afferents, but not much is known regarding their anatomical characteristics. To determine the spinal distribution and neurochemical phenotype of colonic afferents in rodents, Alexa Fluor-conjugated cholera toxin-beta (CTB) was injected subserosally into the proximal and distal portions of the descending colon in Sprague Dawley rats and C57Bl/6 mice. Dorsal root ganglia (T10-S2) were processed for fluorescent immunohistochemistry and visualized by confocal microscopy. In the mouse, CTB-positive neurons were most numerous in the lumbosacral region (LS; L6-S1), with a smaller contribution in the thoracolumbar ganglia (TL; T13-L1). In contrast, CTB-positive neurons in the rat were most numerous in the TL ganglia, with a smaller contribution in the LS ganglia. The vast majority of CTB-positive neurons in both mouse and rat were positive for TRPV1 and CGRP and most likely unmyelinated, in that most colonic afferents were not positive for neurofilament heavy chain. In the mouse, the TL ganglia had a significantly higher percentage of TRPV1- and CGRP-positive neurons than did the LS ganglia, whereas no differences were observed in the rat. The high incidence of TRPV1-positive colonic afferents in rodents suggests that hypersensitivity from the viscera may be partially a TRPV1-mediated event, thereby providing a suitable target for the treatment of visceral pain.

  19. Role of the spinal cord heme oxygenase-carbon monoxide-cGMP pathway in the nociceptive response of rats.

    PubMed

    Nascimento, Carlos G O; Branco, Luiz G S

    2008-02-26

    The aim of the present study was to investigate the role of the spinal cord heme oxygenase (HO)-carbon monoxide (CO)-soluble guanylate cyclase (sGC)-cGMP pathway in nociceptive response of rats to the formalin experimental nociceptive model. Animals were handled and adapted to the experimental environment for a few days before the formalin test was applied. For the formalin test 50 microl of a 1% formalin solution was injected subcutaneously in the dorsal surface of the right hind paw. Following injections, animals were observed for 1 h and flinching behavior was measured as the nociceptive response. Thirty min before the test, rats were pretreated with intrathecal injections with the HO inhibitor, zinc deuteroporphyrin 2,4-bis glycol (ZnDPBG) or heme-lysinate, which is known to induce the HO pathway. Control animals were treated with vehicles. We observed a significant increase in nociceptive response of rats treated with ZnDPBG, and a drastic reduction of flinching nociceptive behavioral response in the heme-lysinate treated animals. Furthermore, the HO pathway seems to act via cGMP, since methylene blue (a sGC inhibitor) prevented the reduction of flinching nociceptive behavioral response caused by heme-lysinate. These findings strongly indicate that the HO pathway plays a spinal antinociceptive role during the formalin test, acting via cGMP.

  20. 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

  1. Time course of immediate early gene protein expression in the spinal cord following conditioning stimulation of the sciatic nerve in rats.

    PubMed

    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.

  2. 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.

  3. Inhibition of acid-sensing ion channels by chlorogenic acid in rat dorsal root ganglion neurons.

    PubMed

    Qu, Zu-Wei; Liu, Ting-Ting; Qiu, Chun-Yu; Li, Jia-Da; Hu, Wang-Ping

    2014-05-01

    Chlorogenic acid (CGA) is one of the most abundant polyphenol compounds in the human diet. Recently, it is demonstrated to have potent antinociceptive effect. However, little is understood about the mechanism underlying CGA analgesia. Here, we have found that CGA can exert an inhibitory effect on the functional activity of native acid-sensing ion channels (ASICs) in rat dorsal root ganglion (DRG) neurons. First, CGA decreased the peak amplitude of proton-gated currents mediated by ASICs in a concentration-dependent manner. Second, CGA shifted the proton concentration-response curve downward, with a decrease of 41.76 ± 8.65% in the maximum current response to protons but with no significant change in the pH0.5 value. Third, CGA altered acidosis-evoked membrane excitability of rat DRG neurons and caused a significant decrease in the amplitude of the depolarization and the number of action potentials induced by acid stimuli. Finally, peripheral administered CGA attenuated nociceptive response to intraplantar injection of acetic acid in rats. ASICs are distributed in peripheral sensory neurons and participate in nociception. Our findings CGA inhibition of native ASICs indicated that CGA may exert analgesic action by modulating ASICs in the primary afferent neurons, which revealed a novel cellular and molecular mechanism underlying CGA analgesia.

  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.

  5. Transganglionic transport of choleragenoid by capsaicin-sensitive C-fibre afferents to the substantia gelatinosa of the spinal dorsal horn after peripheral nerve section.

    PubMed

    Sántha, P; Jancsó, G

    2003-01-01

    Choleratoxin B subunit-binding thick myelinated, A-fibre and unmyelinated, capsaicin-sensitive nociceptive C-fibre primary afferent fibres terminate in a strict topographic and somatotopic manner in the spinal cord dorsal horn. Injection of choleratoxin B subunit-horseradish peroxidase conjugate into injured but not intact peripheral nerves produced transganglionic labelling of primary afferents not only in the deeper layers (Rexed's laminae III-IV), but also in the substantia gelatinosa (Rexed's laminae II) of the spinal dorsal horn. This was interpreted in terms of a sprouting response of the Abeta-myelinated afferents and suggested a contribution to the pathogenesis of neuropathic pain [Nature 355 (1992) 75; J Comp Neurol 360 (1995) 121]. By utilising the selective neurotoxic effect of capsaicin, we examined the role of C-fibre sensory ganglion neurons in the mechanism of this phenomenon. Elimination of these particular, capsaicin-sensitive C-fibre afferents by prior intrathecal or systemic capsaicin treatment inhibited transganglionic labelling by the choleratoxin B subunit-horseradish peroxidase conjugate of the substantia gelatinosa evoked by chronic sciatic nerve section. More importantly, prior perineural capsaicin treatment of the transected nerve proximal to the anticipated site of injection of choleragenoid 12 hours later prevented the labelling of the substantia gelatinosa, but not that of the deeper layers. Electron microscopic examination of the dorsal roots revealed no significant difference in the proportion of labelled myelinated fibres relating to the intact (54.4+/-5.5%) and the transected (62.4+/-5.4%) sciatic nerves. In contrast, the proportion of labelled unmyelinated dorsal root axons relating to the transected, but not the intact nerves showed a significant, six-fold increase after sciatic nerve transection (intact: 4.9+/-1.3%; transected: 35+/-6.7%). These observations indicate that peripheral nerve lesion-induced transganglionic labelling

  6. Injection of nerve growth factor into a low back muscle induces long-lasting latent hypersensitivity in rat dorsal horn neurons.

    PubMed

    Hoheisel, Ulrich; Reuter, Ragna; de Freitas, Milena Fernandes; Treede, Rolf-Detlef; Mense, Siegfried

    2013-10-01

    Little is known about the central mechanisms underlying the transition from local or regional to widespread pain in low back pain patients. The aim of the study was to find out if muscle input induced by injection of nerve growth factor (NGF) can be used as an animal model for studying spinal mechanisms involved in widespread myofascial low back pain. Electrophysiological recordings from rat dorsal horn neurons were made in vivo to study alterations in their responsiveness caused by 2 injections of NGF into the multifidus muscle at an interval of 5 days. NGF is known to be closely associated with many painful muscle disorders. The results demonstrate that the 2 NGF injections-but not a single one-caused a significant hyperexcitability of spinal neurons. Five days after the first NGF injection, the neurons were not significantly sensitized but were easier to sensitize by a second injection. The state of the neurons resembles nociceptive priming. Important findings were that the proportion of neurons having multiple receptive fields (RFs) in various tissues was significantly higher after 2 NGF injections, and new RFs appeared on the distal hind limb. The new RFs were located not in the skin but in deep tissues (muscles, thoracolumbar fascia). If similar changes occur in patients, the data might explain the diffuse nature and spread of myofascial low back pain.

  7. 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

  8. Involvement of spinal nitric oxide (NO) in rat pain-related behaviors induced by the venom of scorpion Buthus martensi Karsch.

    PubMed

    Liu, Tong; Pang, Xue-Yan; Jiang, Feng; Ji, Yong-Hua

    2008-07-01

    In the present study, we investigated the role of spinal nitric oxide (NO) in rat pain-related behaviors induced by the venom of scorpion Buthus martensi Karsch (BmK). The results showed that the number of neuronal NO synthase (nNOS) positive neurons significantly increased in superficial (I-II), deep (V-VI) dorsal horn laminae and the ventral gray laminae (VII-X), but not in the nucleus proprius (III and IV) of bilateral L4-L5 lumbar spinal cord after unilateral intraplantar injection of BmK venom from 2h to 7d. This increase on the ipsilateral side to BmK venom injection was always greater than that on the contralateral side. Western blotting analysis confirmed that spinal nNOS expression was significantly up-regulated following BmK venom administration. In addition, intrathecal delivery of N(omega)-nitro-l-arginine methyl ester hydrochloride (l-NAME; a NOS inhibitor) before intraplantar injection of BmK venom by 10 min significantly attenuated spontaneous nociceptive responses and prevented the development of primary thermal hyperalgesia as well as bilateral mechanical hyperalgesia. Intrathecal injection of l-NAME could also partially inhibit BmK venom-induced c-Fos expression in lumbar spinal cord at 2 h. Thus, the results suggest that spinal NO as a critical mediator is involved in various pain-related behaviors and c-Fos expression induced by BmK venom in rats.

  9. Combining an autologous peripheral nervous system "bridge" and matrix modification by chondroitinase allows robust, functional regeneration beyond a hemisection lesion of the adult rat spinal cord.

    PubMed

    Houle, John D; Tom, Veronica J; Mayes, Debra; Wagoner, Gail; Phillips, Napoleon; Silver, Jerry

    2006-07-12

    Chondroitinase-ABC (ChABC) was applied to a cervical level 5 (C5) dorsal quadrant aspiration cavity of the adult rat spinal cord to degrade the local accumulation of inhibitory chondroitin sulfate proteoglycans. The intent was to enhance the extension of regenerated axons from the distal end of a peripheral nerve (PN) graft back into the C5 spinal cord, having bypassed a hemisection lesion at C3. ChABC-treated rats showed (1) gradual improvement in the range of forelimb swing during locomotion, with some animals progressing to the point of raising their forelimb above the nose, (2) an enhanced ability to use the forelimb in a cylinder test, and (3) improvements in balance and weight bearing on a horizontal rope. Transection of the PN graft, which cuts through regenerated axons, greatly diminished these functional improvements. Axonal regrowth from the PN graft correlated well with the behavioral assessments. Thus, many more axons extended for much longer distances into the cord after ChABC treatment and bridge insertion compared with the control groups, in which axons regenerated into the PN graft but growth back into the spinal cord was extremely limited. These results demonstrate, for the first time, that modulation of extracellular matrix components after spinal cord injury promotes significant axonal regeneration beyond the distal end of a PN bridge back into the spinal cord and that regenerating axons can mediate the return of useful function of the affected limb.

  10. Bradykinin Enhances AMPA and NMDA Receptor Activity in Spinal Cord Dorsal Horn Neurons by Activating Multiple Kinases to Produce Pain Hypersensitivity

    PubMed Central

    Kohno, Tatsuro; Wang, Haibin; Amaya, Fumimasa; Brenner, Gary J.; Cheng, Jen-Kun; Ji, Ru-Rong; Woolf, Clifford J.

    2009-01-01

    Bradykinin potentiates synaptic glutamate release and action in the spinal cord via presynaptic and postsynaptic B2 receptors, contributing thereby to activity-dependent central sensitization and pain hypersensitivity (Wang et al., 2005). We have now examined the signaling pathways that are responsible for the postsynaptic modulatory actions of bradykinin on glutamatergic action and transmission in superficial dorsal horn neurons. B2 receptors are coexpressed in dorsal horn neurons with protein kinase A (PKA) and the δ isoform of protein kinase C (PKC), and we find that the augmentation by bradykinin of AMPA and NMDA receptor-mediated currents in lamina II neurons requires coactivation of both PKC and PKA. The activation of PKA is downstream of COX1 (cyclooxygenase-1). Extracellular signal-regulated kinase (ERK) activation is involved after the PKC and PKA coactivation, and intrathecal administration of bradykinin induces a thermal hyperalgesia in vivo, which is reduced by inhibition of ERK, PKA, and PKC. We conclude that bradykinin, by activating multiple kinases in dorsal horn neurons, potentiates glutamatergic synaptic transmission to produce pain hypersensitivity. PMID:18434532

  11. Long-term effects of brain-derived neurotrophic factor on the frequency of inhibitory synaptic events in the rat superficial dorsal horn.

    PubMed

    Lu, V B; Colmers, W F; Smith, P A

    2009-07-21

    Chronic constriction injury (CCI) of rat sciatic nerve produces a specific pattern of electrophysiological changes in the superficial dorsal horn that lead to central sensitization that is associated with neuropathic pain. These changes can be recapitulated in spinal cord organotypic cultures by long term (5-6 days) exposure to brain-derived neurotrophic factor (BDNF) (200 ng/ml). Certain lines of evidence suggest that both CCI and BDNF increase excitatory synaptic drive to putative excitatory neurons while reducing that to putative inhibitory interneurons. Because BDNF slows the rate of discharge of synaptically-driven action potentials in inhibitory neurons, it should also decrease the frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) throughout the superficial dorsal horn. To test this possibility, we characterized superficial dorsal horn neurons in organotypic cultures according to five electrophysiological phenotypes that included tonic, delay and irregular firing neurons. Five to 6 days of treatment with 200 ng/ml BDNF decreased sIPSC frequency in tonic and irregular neurons as might be expected if BDNF selectively decreases excitatory synaptic drive to inhibitory interneurons. The frequency of sIPSCs in delay neurons was however increased. Further analysis of the action of BDNF on tetrodotoxin-resistant miniature inhibitory postsynaptic currents (mIPSC) showed that the frequency was increased in delay neurons, unchanged in tonic neurons and decreased in irregular neurons. BDNF may thus reduce action potential frequency in those inhibitory interneurons that project to tonic and irregular neurons but not in those that project to delay neurons.

  12. Rat dorsal prostate is necessary for vaginal adhesion of the seminal plug and sperm motility in the uterine horns.

    PubMed

    Tlachi-López, José L; López, Aurora; Hoffman, Kurt; Velázquez-Moctezuma, Javier; García-Lorenzana, Mario; Lucio, Rosa Angélica

    2011-01-01

    The rat prostate comprises dorsal, ventral and lateral lobes that are morphologically and biochemically distinct. Lesions to these structures are expected to affect the quality of the ejaculate and male fertility. In experiment 1, we analyzed ejaculate parameters of males that had chemical lesions of the dorsal or ventral lobes. At pre-lesion and at 5 and 20 days post-lesion males were mated, and after ejaculation, seminal fluid and seminal plug were obtained from the mated females. In experiment 2, the ventral lobes were ablated, and the ejaculate was analyzed. In experiment 3, the fertility of males with chemically-lesioned dorsal lobes or ablation of the ventral lobes was evaluated. Chemical lesion of the dorsal lobe prevented the adhesion of the seminal plug to vaginal walls. When these males were tested at 5-days postlesion, no sperm were found in uterus, and at 20-days post-lesion, the few sperm encountered showed slow progressive motility. None of the females that mated with dorsal lobe-lesioned males became pregnant. However, chemical lesion or ablation of the ventral lobes did not affect ejaculate or fertility. Our results indicate that the dorsal prostatic lobes are indispensable for reproductive success in males, and define parameters of ejaculate with which fertility can be estimated.

  13. 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

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

    PubMed

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

    2013-07-01

    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.

  15. Conditioned place preference and spontaneous dorsal horn neuron activity in chronic constriction injury model in rats

    PubMed Central

    Dalm, Brian D.; Reddy, Chandan G.; Howard, Matthew A.; Kang, Sinyoung; Brennan, Timothy J.

    2016-01-01

    Patients with neuropathic pain commonly present with spontaneous pain, in addition to allodynia and hyperalgesia. While evoked responses in neuropathic pain models are well characterized, determining the presence of spontaneous pain is more challenging. We determined if the chronic constriction injury (CCI) model could be used to measure effects of treatment of spontaneous pain, by evaluating dorsal horn neuron (DHN) spontaneous activity and spontaneous pain-related behaviors. We measured conditioned place preference (CPP) to analgesia produced by sciatic nerve block with bupivacaine in rats with established CCI. We undertook another CPP experiment using hindpaw incision. We also examined DHN spontaneous activity in CCI rats. While CCI produced nocifensive responses to mechanical stimuli, CPP to analgesic nerve block was not evident 14 days following injury: Compared to baseline (314 ± 65 sec), CCI rats did not show a preference for the bupivacaine-paired chamber following conditioning (330 ± 102 sec). On the other hand, sciatic nerve block after hindpaw incision produced CPP on postoperative day 1, serving as a positive control. The proportion of spontaneously active DHNs (33%) was not significantly increased in CCI rats compared to the sham (21%). The median rate of spontaneous activity in the CCI group (12.6 imp/s) was not different from the sham group (9.2 imp/s). Also, there was no change in DHN spontaneous activity following sciatic nerve block with bupivacaine. Our findings suggest that CCI as a neuropathic pain model should not be used to measure effects of treatment of spontaneous pain driven by the peripheral input. PMID:26584420

  16. Temporal and spatial distribution of activated caspase-3 after subdural kainic acid infusions in rat spinal cord.

    PubMed

    Nottingham, Stephanie A; Springer, Joe E

    2003-09-29

    The molecular events initiating apoptosis following traumatic spinal cord injury (SCI) remain poorly understood. Soon after injury, the spinal cord is exposed to numerous secondary insults, including elevated levels of glutamate, that contribute to cell dysfunction and death. In the present study, we attempted to mimic the actions of glutamate by subdural infusion of the selective glutamate receptor agonist, kainic acid, into the uninjured rat spinal cord. Immunohistochemical colocalization studies revealed that activated caspase-3 was present in ventral horn motor neurons at 24 hours, but not 4 hours or 96 hours, following kainic acid treatment. However, at no time point examined was there evidence of significant neuronal loss. Kainic acid resulted in caspase-3 activation in several glial cell populations at all time points examined, with the most pronounced effect occurring at 24 hours following infusion. In particular, caspase-3 activation was observed in a significant number of oligodendroglia in the dorsal and ventral funiculi, and there was a pronounced loss of oligodendroglia at 96 hours following treatment. The results of these experiments indicate a role for glutamate as a mediator of oligodendroglial apoptosis in traumatic SCI. In addition, understanding the apoptotic signaling events activated by glutamate will be important for developing therapies targeting this cell death process.

  17. Somatotopic organization of lumbar muscle-innervating neurons in the ventral horn of the rat spinal cord.

    PubMed

    Takahashi, Yuzuru; Ohtori, Seiji; Takahashi, Kazuhisa

    2010-04-01

    The ventral horn of the rat spinal cord was investigated with respect to the somatotopic organization of the motor neurons that innervate the lumbar muscles. Neurotracer 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) was applied to specific sites in lumbar muscles. Spinal cord segments at L1 through L4 levels were cut into 40-mum serial transverse sections. Labeled neurons were located in the ventromedial nucleus (VM) and lateromedial nucleus (LM) nuclei of Rexed's lamina IX. Motor neurons innervating the m. interspinales lumborum and m. multifidus were without exception present in the VM, whereas all motor neurons innervating the m. rectus abdominis were present in the LM. Forty percent of motor neurons innervating the m. quadratus lumborum were present in the VM and the other 60% were in the LM. Although most of the motor neurons innervating the m. psoas major were present in the LM, a few labeled neurons existed in the VM. These results suggest that the border zone demarcating the areas of innervation of the dorsal and ventral rami of spinal nerves crosses the m. quadratus lumborum.

  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. Estrogens Suppress Spinal Endomorphin 2 Release in Female Rats in Phase with the Estrous Cycle

    PubMed Central

    Kumar, Arjun; Storman, Emiliya M.; Liu, Nai-Jiang; Gintzler, Alan R.

    2015-01-01

    Background/Aims Male and female rats differ in their ability to utilize spinal endomorphin 2 (EM2; the predominant mu-opioid receptor ligand in spinal cord) and in the mechanisms that underlie spinal EM2 analgesic responsiveness. We investigated the relevance of spinal estrogen receptors (ERs) to the in vivo regulation of spinal EM2 release. Methods ER antagonists were administered directly to the lumbosacral spinal cord of male and female rats, intrathecal perfusate was collected, and resulting changes in EM2 release were quantified using a plate-based radioimmunoassay. Results Intrathecal application of an antagonist of either estrogen receptor-α (ERα) or the ER GPR30 failed to alter spinal EM2 release. Strikingly, however, the concomitant blockade of ERα and GPR30 enhanced spinal EM2 release. This effect was sexually dimorphic, being absent in males. Furthermore, the magnitude of the enhancement of spinal EM2 release in females was dependent upon estrous cycle stage, suggesting a relationship with circulating levels of 17β-estradiol. The rapid onset of enhanced EM2 release following intrathecal application of ERα/GPR30 antagonists (within 30–40 min) suggests mediation via ERs in the plasma membrane, not the nucleus. Notably, both ovarian and spinally synthesized estrogens are essential for membrane ER regulation of spinal EM2 release. Conclusion These findings underscore the importance of estrogens for the regulation of spinal EM2 activity and, by extension, endogenous spinal EM2 antinoci-ception in females. Components of the spinal estrogenic mechanism(s) that suppress EM2 release could represent novel drug targets for improving utilization of endogenous spinal EM2, and thereby pain management in women. PMID:25925013

  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. Full inhibition of spinal FAAH leads to TRPV1-mediated analgesic effects in neuropathic rats and possible lipoxygenase-mediated remodeling of anandamide metabolism.

    PubMed

    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.

  2. SPINAL MEDIATION OF MOTOR LEARNING AND MEMORY IN THE RAT FETUS

    PubMed Central

    Robinson, Scott R.

    2014-01-01

    Fetal rats can alter patterns of interlimb coordination after experience with a yoke that links two legs together. Yoke training results in a pronounced increase in conjugate limb movements (CLM). To determine whether yoke motor learning is mediated by spinal cord circuitry, fetal subjects at embryonic day 20 (E20) received yoke training after mid-thoracic spinal cord transection or sham surgery. Both spinal and sham-treated fetuses exhibited an increase in CLM during training. In a second experiment, fetuses received initial yoke training, then were transected or sham treated before a 2nd training. Spinal and sham fetuses that were yoked during both training sessions exhibited a more rapid rise in CLM than those yoked only in the later session. These findings indicate that motor learning in fetal rats can be supported by spinal cord circuitry alone, and that savings implies a form of motor memory localized in the spinal cord. PMID:25735558

  3. 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

  4. Inhibition of acid-sensing ion channel currents by propofol in rat dorsal root ganglion neurons.

    PubMed

    Lei, Zhen; Li, Xiaoyu; Wang, Guizhi; Fei, Jianchun; Meng, Tao; Zhang, Xinyu; Yu, Jingya; Yu, Jingui; Li, Jingxin

    2014-04-01

    Acid-sensing ion channels (ASICs), part of the epithelial sodium channel/degenerin family, are activated by extracellular protons. The ASICs play a significant role in the acidosis-mediated perception of pain. The anaesthetic agent propofol also exerts antinociceptive effects, but the underlying mechanisms for this effect are not clear. We used whole-cell patch clamping to investigate the effect of propofol on proton-gated currents in: (i) rat dorsal root ganglion (DRG) neurons; and (ii) HEK293 cells transfected with either ASIC1a or ASIC3. Propofol inhibited the amplitude of proton-gated currents in DRG neurons, but did not change the sensitivity of ASICs to H(+). Notably, propofol altered acid-evoked excitability of rat DRG neurons and decreased the number of action potentials induced by acid stimuli. In addition, we demonstrated that propofol inhibited ASICs by directly binding with these channels in HEK293 cells. These results suggest that propofol inhibits proton-gated currents in DRG neurons and that inhibition of proton-gated currents explains, in part, the antinociceptive effects of propofol in primary afferent neurons.

  5. Thoracic rat spinal cord contusion injury induces remote spinal gliogenesis but not neurogenesis or gliogenesis in the brain.

    PubMed

    Franz, Steffen; Ciatipis, Mareva; Pfeifer, Kathrin; Kierdorf, Birthe; Sandner, Beatrice; Bogdahn, Ulrich; Blesch, Armin; Winner, Beate; Weidner, Norbert

    2014-01-01

    After spinal cord injury, transected axons fail to regenerate, yet significant, spontaneous functional improvement can be observed over time. Distinct central nervous system regions retain the capacity to generate new neurons and glia from an endogenous pool of progenitor cells and to compensate neural cell loss following certain lesions. The aim of the present study was to investigate whether endogenous cell replacement (neurogenesis or gliogenesis) in the brain (subventricular zone, SVZ; corpus callosum, CC; hippocampus, HC; and motor cortex, MC) or cervical spinal cord might represent a structural correlate for spontaneous locomotor recovery after a thoracic spinal cord injury. Adult Fischer 344 rats received severe contusion injuries (200 kDyn) of the mid-thoracic spinal cord using an Infinite Horizon Impactor. Uninjured rats served as controls. From 4 to 14 days post-injury, both groups received injections of bromodeoxyuridine (BrdU) to label dividing cells. Over the course of six weeks post-injury, spontaneous recovery of locomotor function occurred. Survival of newly generated cells was unaltered in the SVZ, HC, CC, and the MC. Neurogenesis, as determined by identification and quantification of doublecortin immunoreactive neuroblasts or BrdU/neuronal nuclear antigen double positive newly generated neurons, was not present in non-neurogenic regions (MC, CC, and cervical spinal cord) and unaltered in neurogenic regions (dentate gyrus and SVZ) of the brain. The lack of neuronal replacement in the brain and spinal cord after spinal cord injury precludes any relevance for spontaneous recovery of locomotor function. Gliogenesis was increased in the cervical spinal cord remote from the injury site, however, is unlikely to contribute to functional improvement.

  6. Thoracic Rat Spinal Cord Contusion Injury Induces Remote Spinal Gliogenesis but Not Neurogenesis or Gliogenesis in the Brain

    PubMed Central

    Pfeifer, Kathrin; Kierdorf, Birthe; Sandner, Beatrice; Bogdahn, Ulrich; Blesch, Armin; Winner, Beate; Weidner, Norbert

    2014-01-01

    After spinal cord injury, transected axons fail to regenerate, yet significant, spontaneous functional improvement can be observed over time. Distinct central nervous system regions retain the capacity to generate new neurons and glia from an endogenous pool of progenitor cells and to compensate neural cell loss following certain lesions. The aim of the present study was to investigate whether endogenous cell replacement (neurogenesis or gliogenesis) in the brain (subventricular zone, SVZ; corpus callosum, CC; hippocampus, HC; and motor cortex, MC) or cervical spinal cord might represent a structural correlate for spontaneous locomotor recovery after a thoracic spinal cord injury. Adult Fischer 344 rats received severe contusion injuries (200 kDyn) of the mid-thoracic spinal cord using an Infinite Horizon Impactor. Uninjured rats served as controls. From 4 to 14 days post-injury, both groups received injections of bromodeoxyuridine (BrdU) to label dividing cells. Over the course of six weeks post-injury, spontaneous recovery of locomotor function occurred. Survival of newly generated cells was unaltered in the SVZ, HC, CC, and the MC. Neurogenesis, as determined by identification and quantification of doublecortin immunoreactive neuroblasts or BrdU/neuronal nuclear antigen double positive newly generated neurons, was not present in non-neurogenic regions (MC, CC, and cervical spinal cord) and unaltered in neurogenic regions (dentate gyrus and SVZ) of the brain. The lack of neuronal replacement in the brain and spinal cord after spinal cord injury precludes any relevance for spontaneous recovery of locomotor function. Gliogenesis was increased in the cervical spinal cord remote from the injury site, however, is unlikely to contribute to functional improvement. PMID:25050623

  7. AN ELECTRON MICROSCOPE STUDY OF CULTURED RAT SPINAL CORD

    PubMed Central

    Bunge, Richard P.; Bunge, Mary Bartlett; Peterson, Edith R.

    1965-01-01

    Explants prepared from 17- to 18-day fetal rat spinal cord were allowed to mature in culture; such preparations have been shown to differentiate and myelinate in vitro (61) and to be capable of complex bioelectric activity (14–16). At 23, 35, or 76 days, the cultures were fixed (without removal from the coverslip) in buffered OsO4, embedded in Epon, sectioned, and stained for light and electron microscopy. These mature explants generally are composed of several strata of neurons with an overlying zone of neuropil. The remarkable cytological similarity between in vivo and in vitro nervous tissues is established by the following observations. Cells and processes in the central culture mass are generally closely packed together with little intervening space. Neurons exhibit well developed Nissl bodies, elaborate Golgi regions, and subsurface cisternae. Axosomatic and axodendritic synapses, including synaptic junctions between axons and dendritic spines, are present. Typical synaptic vesicles and increased membrane densities are seen at the terminals. Variations in synaptic fine structure (Type 1 and Type 2 synapses of Gray) are visible. Some characteristics of the cultured spinal cord resemble infrequently observed specializations of in vivo central nervous tissue. Neuronal somas may display minute synapse-bearing projections. Occasionally, synaptic vesicles are grouped in a crystal-like array. A variety of glial cells, many apparently at intermediate stages of differentiation, are found throughout the otherwise mature explant. There is ultrastructural evidence of extensive glycogen deposits in some glial processes and scattered glycogen particles in neuronal terminals. This is the first description of the ultrastructure of cultured spinal cord. Where possible, correlation is made between the ultrastructural data and the known physiological properties of these cultures. PMID:14326105

  8. Sulfur dioxide derivatives modulation of high-threshold calcium currents in rat dorsal root ganglion neurons.

    PubMed

    Du, Zhengqing; Meng, Ziqiang

    2006-09-11

    This study addressed the effect of sulfur dioxide (SO(2)) derivatives on high-voltage-activated calcium currents (HVA-I(Ca)) in somatic membrane of freshly isolated rat dorsal root ganglion (DRG) neurons by using the whole-cell configuration of patch-clamp technique. High-threshold Ca(2+) channels are highly expressed in small dorsal root ganglion neurons. SO(2) derivatives increased the amplitudes of calcium currents in a concentration-dependent and voltage-dependent manner. The 50% enhancement concentrations (EC(50)) of SO(2) derivatives on HVA-I(Ca) was about 0.4 microM. In addition, SO(2) derivatives significantly shifted the activation and inactivation curve in the depolarizing direction. Parameters for the fit of a Boltzmann equation to mean values for the activation were V(1/2)=-17.9+/-1.3 mV before and -12.5+/-1.1 mV after application 0.5 microM SO(2) derivatives 2 min (P<0.05). The half inactivation of HVA-I(Ca) was shifted 9.7 mV to positive direction (P<0.05). Furthermore, SO(2) derivatives significantly prolonged the slow constant of inactivation, slowed the fast recovery but markedly accelerated the slow recovery of HVA-I(Ca) from inactivation. From HP of -60 mV 0.5 microM SO(2) derivatives increased the amplitude of HVA-I(Ca) with a depolarizing voltage step to -10 mV about 54.0% in small DRG neurons but 33.3% in large DRG neurons. These results indicated a possible correlation between the change of calcium channels and SO(2) inhalation toxicity, which might cause periphery neurons abnormal regulation of nociceptive transmission via calcium channels.

  9. ATF3 is a novel nuclear marker for migrating ependymal stem cells in the rat spinal cord.

    PubMed

    Mladinic, Miranda; Bianchetti, Elena; Dekanic, Ana; Mazzone, Graciela L; Nistri, Andrea

    2014-05-01

    The present study identified ATF3 as a novel dynamic marker for ependymal stem/progenitor cells (nestin, vimentin and SOX2 positive) around the central canal of the neonatal or adult rat spinal cord. While quiescent ependymal cells showed cytoplasmic ATF3 expression, during 6-24h in vitro these cells mobilized and acquired intense nuclear ATF3 staining. Their migratory pattern followed a centrifugal pathway toward the dorsal and ventral funiculi, reminiscent of the rostral migratory stream of the brain subventricular stem cells. Thus, the chain cell formation was, by analogy, termed funicular migratory stream (FMS). The FMS process preceded the strong proliferation of ependymal cells occurring only after 24h in vitro. Pharmacological inhibition of MAPK-p38 and JNK/c-Jun (upstream effectors of ATF3 activation) prevented the FMS mobilization of ATF3 nuclear-positive cells. Excitotoxicity or ischemia-like conditions, reported to evoke neuronal and glial injury, did not further enhance migration of ependymal cells at 24h, suggesting that, at this early stage of damage, the FMS phenomenon had peaked and that more extensive repair processes are delayed beyond this time point. ATF3 is, therefore, useful to identify activation and migration of endogenous stem cells of the rat spinal cord in vitro.

  10. Spatiotemporal expression of Ski after rat spinal cord injury.

    PubMed

    Zhou, Kaisheng; Nan, Wei; Feng, Dongliang; Yi, Zhigang; Zhu, Yandong; Long, Zaiyun; Li, Sen; Zhang, Haihong; Wu, Yamin

    2017-02-08

    Ski is an evolutionarily conserved protein and widely participates in the regulation of various pathological and physiological processes such as wound healing, liver regeneration, development of the embryonic nervous system, muscle differentiation, and progression of many kinds of tumors. However, the distribution and function of Ski in central nervous system lesion and disease remain unclear. In this study, we investigated the spatiotemporal expression of Ski in a spinal cord injury (SCI) model in adult rats. Western Blot analysis indicated that Ski was expressed in both normal and injured spinal cord, and showed a significant upregulation after SCI compared with the sham group. Double-labeled immunofluorescence staining showed that Ski was significantly expressed in astrocytes, but not in the neurons. Western Blot analyses of glial fibrillary acidic protein (GFAP) and BBB scores were carried out and correlation analysis showed a positive correlation between them. In addition, the relative expression level of Ski was also positively correlated with the relative expression level of GFAP. Moreover, the conspicuous co-expression band of Ski and GFAP at the lesion border was found in the results of immunofluorescence staining combined with the pattern of glial scar formation reflected by H&E staining; in addition, it was found that Ski was also highly associated with glial scar. On the basis of our data, we speculated that Ski might play an important role in the process of reactive astrogliosis after SCI and our study might provide a basis for further study on the detailed role of Ski in astrocytes.

  11. Label-free identification of the microstructure of rat spinal cords based on nonlinear optical microscopy.

    PubMed

    Liao, C X; Wang, Z Y; Zhou, Y; Zhou, L Q; Zhu, X Q; Liu, W G; Chen, J X

    2017-03-20

    The spinal cord is a vital link between the brain and the body and mainly comprises neurons, glial cells and nerve fibres. In this work, nonlinear optical (NLO) microscopy based on intrinsic tissue properties was employed to label-freely analyze the cells and matrix in spinal cords at a molecular level. The high-resolution and high-contrast NLO images of unstained spinal cords demonstrate that NLO microscopy has the ability to show the microstructure of white and grey matter including ventral horn, intermediate area, dorsal horns, ventral column, lateral column and dorsal column. Neurons with various sizes were identified in grey matter by dark spots of nonfluorescent nuclei encircled by cytoplasm-emitting two-photon excited fluorescence signals. Nerve fibres and neuroglias were observed in white matter. Besides, the spinal arteries were clearly presented by NLO microscopy. Using spectral and morphological information, this technique was proved to be an effective tool for label-freely imaging spinal cord tissues, based on endogenous signals in biological tissue. With future development, we foresee promising applications of the NLO technique for in vivo, real-time assessment of spinal cord diseases or injures.

  12. 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.

  13. Morphine inhibits acid-sensing ion channel currents in rat dorsal root ganglion neurons.

    PubMed

    Cai, Qi; Qiu, Chun-Yu; Qiu, Fang; Liu, Ting-Ting; Qu, Zu-Wei; Liu, Yu-Min; Hu, Wang-Ping

    2014-03-20

    Extracellular acidosis is a common feature in pain-generating pathological conditions. Acid-sensing ion channels (ASICs), pH sensors, are distributed in peripheral sensory neurons and participate in nociception. Morphine exerts potent analgesic effects through the activation of opioid receptors for various pain conditions. A cross-talk between ASICs and opioid receptors in peripheral sensory neurons has not been shown so far. Here, we have found that morphine inhibits the activity of native ASICs in rat dorsal root ganglion (DRG) neurons. Morphine dose-dependently inhibited proton-gated currents mediated by ASICs in the presence of the TRPV1 inhibitor capsazepine. Morphine shifted the proton concentration-response curve downwards, with a decrease of 51.4±3.8% in the maximum current response but with no significant change in the pH0.5 value. Another μ-opioid receptor agonist DAMGO induced a similar decrease in ASIC currents compared with morphine. The morphine inhibition of ASIC currents was blocked by naloxone, a specific opioid receptor antagonist. Pretreatment of forskolin, an adenylyl cyclase activator, or the addition of cAMP reversed the inhibitory effect of morphine. Moreover, morphine altered acid-evoked excitability of rat DRG neurons and decreased the number of action potentials induced by acid stimuli. Finally, peripheral applied morphine relieved pain evoked by intraplantar of acetic acid in rats. Our results indicate that morphine can inhibit the activity of ASICs via μ-opioid receptor and cAMP dependent signal pathway. These observations demonstrate a cross-talk between ASICs and opioid receptors in peripheral sensory neurons, which was a novel analgesic mechanism of morphine.

  14. N-methyl-D-aspartate receptor antagonist MK-801 prevents apoptosis in rats that have undergone fetal spinal cord transplantation following spinal hemisection.

    PubMed

    Zhang, Qiang; Shao, Yang; Zhao, Changsong; Cai, Juan; Sun, Sheng

    2014-12-01

    Spinal cord injury is the main cause of paraplegia, but effective therapies for it are lacking. Embryonic spinal cord transplantation is able to repair spinal cord injury, albeit with a large amount of neuronal apoptosis remaining in the spinal cord. MK-801, an N-methyl-D-aspartate (NMDA) receptor antagonist, is able to reduce cell death by decreasing the concentration of excitatory amino acids and preventing extracellular calcium ion influx. In this study, the effect of MK-801 on the apoptosis of spinal cord neurons in rats that have received a fetal spinal cord (FSC) transplant following spinal hemisection was investigated. Wistar rats were divided into three groups: Spinal cord hemisection injury with a combination of FSC transplantation and MK-801 treatment (group A); spinal cord hemisection injury with FSC transplantation (group B); and spinal cord injury with insertion of a Gelfoam pledget (group C). The rats were sacrificed 1, 3, 7 and 14 days after the surgery. Apoptosis in spinal slices from the injured spinal cord was examined by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling reaction, and the expression of B-cell lymphoma-2 (Bcl-2) was measured by immunohistochemistry. The positive cells were quantitatively analyzed using a computer image analysis system. The rate of apoptosis and the positive expression of Bcl-2 protein in the spinal cord neurons in the three groups decreased in the following order: C>B>A (P<0.05) and A>B>C (P<0.05), respectively. This indicates that treatment with the NMDA receptor antagonist MK-801 prevents apoptosis in the spinal cord neurons of rats that have undergone FSC transplantation following spinal hemisection.

  15. Neutrophils Infiltrate the Spinal Cord Parenchyma of Rats with Experimental Diabetic Neuropathy

    PubMed Central

    Newton, Victoria L.; Guck, Jonathan D.; Cotter, Mary A.

    2017-01-01

    Spinal glial cell activation and cytokine secretion have been implicated in the etiology of neuropathic pain in a number of experimental models, including diabetic neuropathy. In this study, streptozotocin- (STZ-) induced diabetic rats were either untreated or treated with gabapentin (50 mg/kg/day by gavage for 2 weeks, from 6 weeks after STZ). At 8 weeks after STZ, hypersensitivity was confirmed in the untreated diabetic rats as a reduced response threshold to touch, whilst mechanical thresholds in gabapentin-treated diabetic rats were no different from controls. Diabetes-associated thermal hypersensitivity was also ameliorated by gabapentin. We performed a cytokine profiling array in lumbar spinal cord samples from control and diabetic rats. This revealed an increase in L-selectin, an adhesion molecule important for neutrophil transmigration, in the spinal cord of diabetic rats but not diabetic rats treated with gabapentin. Furthermore, we found an increase in the number of neutrophils present in the parenchyma of the spinal cord, which was again ameliorated in gabapentin-treated diabetic rats. Therefore, we suggest that dysregulated spinal L-selectin and neutrophil infiltration into the spinal cord could contribute to the pathogenesis of painful diabetic neuropathy. PMID:28293643

  16. Effects of depressant amino acids and antagonists on an in vitro spinal cord preparation from the adult rat.

    PubMed

    Long, S K; Evans, R H; Krijzer, F

    1989-07-01

    A mature sacrococcygeal in vitro spinal preparation from the rat has been used to demonstrate effects of neutral amino acids and their antagonists. gamma-Aminobutanoate (GABA), glycine and taurine (0.5-5 mM) produced dose-dependent depression of spontaneous paroxysmal activity generated in Mg2+ -free medium. The depressant effect of GABA was antagonised selectively by picrotoxin (25-50 microM) and the depressant effects of glycine and taurine were antagonised selectively by strychnine (0.2 microM). Glycine (0.5-5 mM) had a dose-dependent depolarizing action which was present at the central ends of isolated ventral roots. gamma-Aminobutanoate and taurine, had only weak depolarizing actions on ventral root fibres. Depolarizing responses to glycine showed a marked fading. Reduction in the fading appeared to be responsible for a paradoxical potentiation of glycine-induced depolarizations, which occurred in the presence of strychnine (0.2-2 microM). Strychnine (2-10 microM), picrotoxin (10-50 microM) or bicuculline (10 microM) had little or no effect on the amplitude, duration or latency of the monosynaptic component of ventral root reflexes evoked by supramaximal stimulation of dorsal roots (DR-VRP). However all three antagonists introduced slow, NMDA receptor mediated, components to these ventral root potentials. Picrotoxin and bicuculline, but not strychnine, reversibly depressed the dorsal root potential evoked from an adjacent dorsal root (DR-DRP). The depressant actions of 2-amino-5-phosphonopentanoate (AP5), kynurenate and 3-((+/-)-2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) revealed both NMDA and non-NMDA receptor mediated components in the dorsal root potential.

  17. Tet1-dependent epigenetic modification of BDNF expression in dorsal horn neurons mediates neuropathic pain in rats

    PubMed Central

    Hsieh, Ming-Chun; Lai, Cheng-Yuan; Ho, Yu-Cheng; Wang, Hsueh-Hsiao; Cheng, Jen-Kun; Chau, Yat-Pang; Peng, Hsien-Yu

    2016-01-01

    Ten-eleven translocation methylcytosine dioxygenase 1 (Tet1) mediates the conversion of 5-methylcytosine (5 mC) to 5-hydroxymethylcytosine (5 hmC), hence promoting DNA demethylation. Although recent studies have linked the DNA demethylation of specific genes to pain hypersensitivity, the role of spinal Tet1-dependent DNA demethylation in nociception hypersensitivity development remains elusive. Here, we report correlated with behavioral allodynia, spinal nerve ligation (SNL) upregulated Tet1 expression in dorsal horn neurons that hydroxylate 5 mC to 5 hmC at CpG dinucleotides in the bdnf promoter to promote spinal BDNF expression at day 7 after operation. Focal knockdown of spinal Tet1 expression decreased Tet1 binding and 5 hmC enrichment, further increased 5 mC enrichment at CpG sites in the bdnf promoter and decreased spinal BDNF expression accompanied by the alleviation of the developed allodynia. Moreover, at day 7 after operation, SNL-enhanced Tet1 expression also inhibited the binding of DNA methyltransferases (DNMTs, i.e., DNMT1, DNMT3a, and DNMT3b) to the bdnf promoter, a requirement for transcriptional silencing by catalysing 5-cytosine (5C) to 5 mC. Together, these data suggest at CpG sites of the bdnf promoter, SNL-enhanced Tet1 expression promotes DNA demethylation both by converting 5 mC to 5 hmC and inhibiting DNMT binding to regulate spinal BDNF expression, hence contributing to behavioral allodynia development. PMID:27857218

  18. Rat models of spinal cord injury: from pathology to potential therapies

    PubMed Central

    2016-01-01

    ABSTRACT A long-standing goal of spinal cord injury research is to develop effective spinal cord repair strategies for the clinic. Rat models of spinal cord injury provide an important mammalian model in which to evaluate treatment strategies and to understand the pathological basis of spinal cord injuries. These models have facilitated the development of robust tests for assessing the recovery of locomotor and sensory functions. Rat models have also allowed us to understand how neuronal circuitry changes following spinal cord injury and how recovery could be promoted by enhancing spontaneous regenerative mechanisms and by counteracting intrinsic inhibitory factors. Rat studies have also revealed possible routes to rescuing circuitry and cells in the acute stage of injury. Spatiotemporal and functional studies in these models highlight the therapeutic potential of manipulating inflammation, scarring and myelination. In addition, potential replacement therapies for spinal cord injury, including grafts and bridges, stem primarily from rat studies. Here, we discuss advantages and disadvantages of rat experimental spinal cord injury models and summarize knowledge gained from these models. We also discuss how an emerging understanding of different forms of injury, their pathology and degree of recovery has inspired numerous treatment strategies, some of which have led to clinical trials. PMID:27736748

  19. Rat models of spinal cord injury: from pathology to potential therapies.

    PubMed

    Kjell, Jacob; Olson, Lars

    2016-10-01

    A long-standing goal of spinal cord injury research is to develop effective spinal cord repair strategies for the clinic. Rat models of spinal cord injury provide an important mammalian model in which to evaluate treatment strategies and to understand the pathological basis of spinal cord injuries. These models have facilitated the development of robust tests for assessing the recovery of locomotor and sensory functions. Rat models have also allowed us to understand how neuronal circuitry changes following spinal cord injury and how recovery could be promoted by enhancing spontaneous regenerative mechanisms and by counteracting intrinsic inhibitory factors. Rat studies have also revealed possible routes to rescuing circuitry and cells in the acute stage of injury. Spatiotemporal and functional studies in these models highlight the therapeutic potential of manipulating inflammation, scarring and myelination. In addition, potential replacement therapies for spinal cord injury, including grafts and bridges, stem primarily from rat studies. Here, we discuss advantages and disadvantages of rat experimental spinal cord injury models and summarize knowledge gained from these models. We also discuss how an emerging understanding of different forms of injury, their pathology and degree of recovery has inspired numerous treatment strategies, some of which have led to clinical trials.

  20. Anatomic, intrinsic, and synaptic properties of dorsal and ventral division neurons in rat medial geniculate body.

    PubMed

    Bartlett, E L; Smith, P H

    1999-05-01

    Anatomic, intrinsic, and synaptic properties of dorsal and ventral division neurons in rat medial geniculate body. Presently little is known about what basic synaptic and cellular mechanisms are employed by thalamocortical neurons in the two main divisions of the auditory thalamus to elicit their distinct responses to sound. Using intracellular recording and labeling methods, we characterized anatomic features, membrane properties, and synaptic inputs of thalamocortical neurons in the dorsal (MGD) and ventral (MGV) divisions in brain slices of rat medial geniculate body. Quantitative analysis of dendritic morphology demonstrated that tufted neurons in both divisions had shorter dendrites, smaller dendritic tree areas, more profuse branching, and a greater dendritic polarization compared with stellate neurons, which were only found in MGD. Tufted neuron dendritic polarization was not as strong or consistent as earlier Golgi studies suggested. MGV and MGD cells had similar intrinsic properties except for an increased prevalence of a depolarizing sag potential in MGV neurons. The sag was the only intrinsic property correlated with cell morphology, seen only in tufted neurons in either division. Many MGV and MGD neurons received excitatory and inhibitory inferior colliculus (IC) inputs (designated IN/EX or EX/IN depending on excitation/inhibition sequence). However, a significant number only received excitatory inputs (EX/O) and a few only inhibitory (IN/O). Both MGV and MGD cells displayed similar proportions of response combinations, but suprathreshold EX/O responses only were observed in tufted neurons. Excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs) had multiple distinguishable amplitude levels implying convergence. Excitatory inputs activated alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptors the relative contributions of which were variable. For IN/EX cells with suprathreshold inputs

  1. 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

  2. Intracerebroventricular morphine decreases descending inhibitions acting on lumbar dorsal horn neuronal activities related to pain in the rat.

    PubMed

    Bouhassira, D; Villanueva, L; Le Bars, D

    1988-10-01

    Recordings were made from convergent neurons in the lumbar dorsal horn of the rat. These neurons were activated by both innocuous and noxious stimuli applied to their excitatory receptive fields located on the extremity of the ipsilateral hindpaw. Transcutaneous application of suprathreshold 2-msec square-wave pulses to the center of the receptive field resulted in responses to A- and C-fiber activation being observed: 27.2 +/- 2.2 (mean +/- S.E.M.) C-fiber latency spikes were evoked per stimulus. This type of response was inhibited by applying noxious conditioning stimuli to heterotopic areas of the body; in particular, immersing the tail in a 52 degrees C waterbath caused a 74.2 +/- 2.0% inhibition of the C-fiber evoked responses; such inhibitory processes have been termed diffuse noxious inhibitory controls (DNIC). The effects of microinjections of morphine (0.6-40 micrograms; 2 microliter) within the 3rd ventricle on both the unconditioned C-fiber-evoked responses and the inhibitory processes triggered from the tail were investigated in an attempt to answer two questions: 1) does i.c.v. morphine increase tonic descending inhibitory processes? and 2) what are the effects of i.c.v. morphine on descending inhibitory processes triggered phasically by noxious stimuli? The predominant effect of i.c.v. morphine on the C-fiber-evoked responses was a facilitation (17 of 26 cases). Such a facilitation was dose-related in the 0.6 to 40 microgram range and naloxone reversible; it plateaued from 20 min after the microinjection. No clear relationship was found between the number of C-fiber evoked responses in the control sequences and the subsequent effect of i.c.v. morphine. Intracerebroventricular morphine clearly reduced DNIC in the majority of cases (21 of 26). Such a reduction was dose-related in the 0.6 to 2.5 microgram range and naloxone reversible; it plateaued within 90 min of microinjection. No clear relationship was found between the changes in DNIC and either the

  3. 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

  4. A PARYLENE-BASED MICROELECTRODE ARRAY IMPLANT FOR SPINAL CORD STIMULATION IN RATS.

    PubMed

    Nandra, Mandheerej S; Lavrov, Igor A; Edgerton, V Reggie; Tai, Yu-Chong

    2011-01-23

    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.

  5. Developmental localization of calcitonin gene-related peptide in dorsal sensory axons and ventral motor neurons of mouse cervical spinal cord.

    PubMed

    Kim, Jeongtae; Sunagawa, Masanobu; Kobayashi, Shiori; Shin, Taekyun; Takayama, Chitoshi

    2016-04-01

    Calcitonin gene-related peptide (CGRP) is a 37-amino-acid neuropeptide, synthesized by alternative splicing of calcitonin gene mRNA. CGRP is characteristically distributed in the nervous system, and its function varies depending on where it is expressed. To reveal developmental formation of the CGRP network and its function in neuronal maturation, we examined the immunohistochemical localization of CGRP in the developing mouse cervical spinal cord and dorsal root ganglion. CGRP immunolabeling (IL) was first detected in motor neurons on E13, and in ascending axons of the posterior funiculus and DRG neurons on E14. CGRP-positive sensory axon fibers entered Laminae I and II on E16, and Laminae I through IV on E18. The intensity of the CGRP-IL gradually increased in both ventral and dorsal horns during embryonic development, but markedly decreased in the ventral horn after birth. These results suggest that CGRP is expressed several days after neuronal settling and entry of sensory fibers, and that the CGRP network is formed in chronological and sequential order. Furthermore, because CGRP is markedly expressed in motor neurons when axons are vastly extending and innervating targets, CGRP may also be involved in axonal elongation and synapse formation during normal development.

  6. Modulation of bladder afferent signals in normal and spinal cord-injured rats by purinergic P2X3 and P2X2/3 receptors

    PubMed Central

    Munoz, Alvaro; Somogyi, George T.; Boone, Timothy B.; Ford, Anthony P.; Smith, Christopher P.

    2015-01-01

    OBJECTIVE • To evaluate the role of bladder sensory purinergic P2X3 and P2X2/3 receptors on modulating the activity of lumbosacral neurones and urinary bladder contractions in vivo in normal or spinal cord-injured (SCI) rats with neurogenic bladder overactivity. MATERIALS AND METHODS • SCI was induced in female rats by complete transection at T8 – T9 and experiments were performed 4 weeks later, when bladder overactivity developed. Non-transected rats were used as controls (normal rats). • Neural activity was recorded in the dorsal horn of the spinal cord and field potentials were acquired in response to intravesical pressure steps via a suprapubic catheter. Field potentials were recorded under control conditions, after stimulation of bladder mucosal purinergic receptors with intravesical ATP (1 mm), and after intravenous injection of the P2X3/P2X2/3 antagonist AF-353 (10 mg/kg and 20 mg/kg). • Cystometry was performed in urethaneanaesthetised rats intravesically infused with saline. AF-353 (10 mg/kg) was systemically applied after baseline recordings; the rats also received a second dose of AF-353 (20 mg/kg). Changes in the frequency of voiding (VC) and non-voiding (NVC) contractions were evaluated. RESULTS • SCI rats had significantly higher frequencies for field potentials and NVC than NL rats. Intravesical ATP increased field potential frequency in control but not SCI rats, while systemic AF-353 significantly reduced this parameter in both groups. • AF-353 also reduced the inter-contractile interval in control but not in SCI rats; however, the frequency of NVC in SCI rats was significantly reduced. CONCLUSION • The P2X3/P2X2/3 receptors on bladder afferent nerves positively regulate sensory activity and NVCs in overactive bladders. PMID:22540742

  7. Neurotoxic lesions of the dorsal hippocampus and Pavlovian fear conditioning in rats.

    PubMed

    Maren, S; Aharonov, G; Fanselow, M S

    1997-11-01

    Electrolytic lesions of the dorsal hippocampus (DH) produce deficits in both the acquisition and expression of conditional fear to contextual stimuli in rats. To assess whether damage to DH neurons is responsible for these deficits, we performed three experiments to examine the effects of neurotoxic N-methyl-D-aspartate (NMDA) lesions of the DH on the acquisition and expression of fear conditioning. Fear conditioning consisted of the delivery of signaled or unsignaled footshocks in a novel conditioning chamber and freezing served as the measure of conditional fear. In Experiment 1, posttraining DH lesions produced severe retrograde deficits in context fear when made either 1 or 28, but not 100, days following training. Pretraining DH lesions made 1 week before training did not affect contextual fear conditioning. Tone fear was impaired by DH lesions at all training-to-lesion intervals. In Experiment 2, posttraining (1 day), but not pretraining (1 week), DH lesions produced substantial deficits in context fear using an unsignaled shock procedure. In Experiment 3, pretraining electrolytic DH lesions produced modest deficits in context fear using the same signaled and unsignaled shock procedures used in Experiments 1 and 2, respectively. Electrolytic, but not neurotoxic, lesions also increased pre-shock locomotor activity. Collectively, this pattern of results reveals that neurons in the DH are not required for the acquisition of context fear, but have a critical and time-limited role in the expression of context fear. The normal acquisition and expression of context fear in rats with neurotoxic DH lesions made before training may be mediated by conditioning to unimodal cues in the context, a process that may rely less on the hippocampal memory system.

  8. PKCɛ mediates substance P inhibition of GABAA receptors-mediated current in rat dorsal root ganglion.

    PubMed

    Li, Li; Zhao, Lei; Wang, Yang; Ma, Ke-tao; Shi, Wen-yan; Wang, Ying-zi; Si, Jun-qiang

    2015-02-01

    The mechanism underlying the modulatory effect of substance P (SP) on GABA-activated response in rat dorsal root ganglion (DRG) neurons was investigated. In freshly dissociated rat DRG neurons, whole-cell patch-clamp technique was used to record GABA-activated current and sharp electrode intracellular recording technique was used to record GABA-induced membrane depolarization. Application of GABA (1-1000 μmol/L) induced an inward current in a concentration-dependent manner in 114 out of 127 DRG neurons (89.8 %) examined with whole-cell patch-clamp recordings. Bath application of GABA (1-1000 μmol/L) evoked a depolarizing response in 236 out of 257 (91.8%) DRG neurons examined with intracellular recordings. Application of SP (0.001-1 μmol/L) suppressed the GABA-activated inward current and membrane depolarization. The inhibitory effects were concentration-dependent and could be blocked by the selective neurokinin 1 (NK1) receptors antagonist spantide but not by L659187 and SR142801 (1 μmol/L, n=7), selective antagonists of NK2 and NK3. The inhibitory effect of SP was significantly reduced by the calcium chelator BAPTA-AM, phospholipase C (PLC) inhibitor U73122, and PKC inhibitor chelerythrine, respectively. The PKA inhibitor H-89 did not affect the SP effect. Remarkably, the inhibitory effect of SP on GABA-activated current was nearly completely removed by a selective PKCε inhibitor epilon-V1-2 but not by safingol and LY333531, selective inhibitors of PKCα and PKCβ. Our results suggest that NK1 receptor mediates SP-induced inhibition of GABA-activated current and membrane depolarization by activating intracellular PLC-Ca²⁺-PKCε cascade. SP might regulate the excitability of peripheral nociceptors through inhibition of the "pre-synaptic inhibition" evoked by GABA, which may explain its role in pain and neurogenic inflammation.

  9. The Postnatal Development of Spinal Sensory Processing

    NASA Astrophysics Data System (ADS)

    Fitzgerald, Maria; Jennings, Ernest

    1999-07-01

    The mechanisms by which infants and children process pain should be viewed within the context of a developing sensory nervous system. The study of the neurophysiological properties and connectivity of sensory neurons in the developing spinal cord dorsal horn of the intact postnatal rat has shed light on the way in which the newborn central nervous system analyzes cutaneous innocuous and noxious stimuli. The receptive field properties and evoked activity of newborn dorsal horn cells to single repetitive and persistent innocuous and noxious inputs are developmentally regulated and reflect the maturation of excitatory transmission within the spinal cord. These changes will have an important influence on pain processing in the postnatal period.

  10. Effects of nano red elemental selenium on sodium currents in rat dorsal root ganglion neurons.

    PubMed

    Yuan, Huijun; Lin, Jiarui; Lan, Tonghan

    2006-01-01

    Nano red elemental selenium (Nano-Se), was demonstrated to be useful in medical and scientific researches. Here, we investigated the effects of Nano-Se on sodium currents on rat dorsal root ganglion neurons (DRG), using the whole-cell patch clamp method. Nano-Se reversibly decrease the I(Na)(TTX-S) in a concentration-dependent, time-dependent and open-channel block manners without affecting I(Na)(TTX-R). It shifted the steady-state activation and inactivation curves for I(Na) to more negative potentials. In the research of recovery from inactivation, the recovery time constant is longer in the present of Nano-Se. Nano-Se had a weaker inhibitory effect on I(Na), compared with marked decrease caused by selenite which indicated that Nano-Se is less neurotoxic than selenite in short-term/large dose treatments and had similar bio availability to sodium selenite. The results of interaction between the effects of Nano-Se and selenite on sodium currents indicated a negative allosteric interaction between the selenite binding site and the Nano-Se binding site or that they have the same competitive binding site.

  11. Taurine-induced modulation of voltage-sensitive Na+ channels in rat dorsal root ganglion neurons.

    PubMed

    Yu, Shan-Shan; Yu, Kuai; Gu, Yan; Ruan, Di-Yun

    2005-08-15

    The physiological role of taurine, an abundant free amino acid in the neural system, is still poorly understood. The aim of this study was to investigate its effect on TTX-sensitive (TTX-S) and TTX-resistant (TTX-R) Na+ currents in enzymatically dissociated neurons from rat dorsal root ganglion (DRG) with conventional whole-cell recording manner under voltage-clamp conditions. A TTX-S Na+ current was recorded preferentially from large DRG neurons and a TTX-R Na+ current preferentially from small ones. For TTX-S Na+ channel, taurine of the concentration > or = 10 mM shifted the activation curve in the depolarizing direction and the inactivation curve in the hyperpolarizing direction. There was no change in the activation curve for TTX-R Na+ channel and the inactivation curve was shifted in the hyperpolarizing direction slightly in the presence of taurine > or = 20 mM. When the recovery kinetics was examined, the presence of taurine resulted in a slower recovery from inactivation of TTX-S currents and no change of TTX-R ones. All the effects of taurine were weakly concentration-dependent and partly recovered quite slowly after washout. Our data indicate that taurine alters the properties of Na+ currents in intact DRG neurons. These may contribute to the understanding of taurine as a natural neuroprotectant and the potential of taurine as a useful medicine for the treatment of sensory neuropathies.

  12. CREB overexpression in dorsal CA1 ameliorates long-term memory deficits in aged rats

    PubMed Central

    Yu, Xiao-Wen; Curlik, Daniel M; Oh, M Matthew; Yin, Jerry CP; Disterhoft, John F

    2017-01-01

    The molecular mechanisms underlying age-related cognitive deficits are not yet fully elucidated. In aged animals, a decrease in the intrinsic excitability of CA1 pyramidal neurons is believed to contribute to age-related cognitive impairments. Increasing activity of the transcription factor cAMP response element-binding protein (CREB) in young adult rodents facilitates cognition, and increases intrinsic excitability. However, it has yet to be tested if increasing CREB expression also ameliorates age-related behavioral and biophysical deficits. To test this hypothesis, we virally overexpressed CREB in CA1 of dorsal hippocampus. Rats received CREB or control virus, before undergoing water maze training. CREB overexpression in aged animals ameliorated the long-term memory deficits observed in control animals. Concurrently, cells overexpressing CREB in aged animals had reduced post-burst afterhyperpolarizations, indicative of increased intrinsic excitability. These results identify CREB modulation as a potential therapy to treat age-related cognitive decline. DOI: http://dx.doi.org/10.7554/eLife.19358.001 PMID:28051768

  13. Nicotine withdrawal upregulates nitrergic and galaninergic activity in the rat dorsal raphe nucleus and locus coeruleus.

    PubMed

    Okere, Chuma O; Waterhouse, Barry D

    2013-03-01

    The dorsal raphe nucleus (DRN), a major source of forebrain serotonin, mediates various neural functions including anxiety. The nucleus locus coeruleus (LC) is likewise involved in mediating central components of the stress response and anxiety. An anxiety-reducing effect is widely believed to underlie many cases of nicotine dependence. While much is known about nicotine-serotonin interactions, little is known about how nicotine engages the DRN non-serotonergic domain in specific physiological functions that influence organismal behavior. The aim of this study was to determine how chronic nicotine withdrawal influences neuronal nitric oxide (NO) synthase (nNOS) and galanin immunoreactivity in the DRN and LC of adult rats. Compared with saline, nicotine increased nicotinamide adenine dinucleotide phosphate diaphorase profiles within distinct DRN subregions and also enhanced intensity in nNOS and galanin cell bodies in the rostral DRN as well as galanin in the LC. Nicotine-induced nNOS/galanin staining of somata was abundant in the rostral ventromedial DRN. Galanin-positive terminals surrounded nNOS-containing cell bodies in the DRN lateral wing subregions. These observations suggest that the DRN NOS-galanin domain and galanin in the LC are engaged in the organism's neural adaptation to chronic nicotine exposure. Hence NO and galanin synthesized or released within the DRN and LC or at the respective target sites might regulate the whole animal behavioral response to nicotine exposure.

  14. Neuroanatomical study on the tecto-suprageniculate-dorsal auditory cortex pathway in the rat.

    PubMed

    Horie, M; Meguro, R; Hoshino, K; Ishida, N; Norita, M

    2013-01-03

    Previous anatomical and physiological studies suggest that the superior colliculus sends integrated sensory information to the multimodal cortical areas via the thalamic suprageniculate nucleus (SG). However, the detailed distribution of rat tecto-SG axon terminals and SG neurons projecting to the multimodal cortex, as well as synaptic connections between these tectal axons and SG neurons, remains unclear. In this study, the organization of the tecto-thalamo-cortical pathway was investigated via combined injections of anterograde and retrograde tracers followed by light and electron microscopic observations. Injections of a retrograde tracer, cholera toxin B subunit (CTB), into the temporal cortex, area 2, dorsal part (Te2D), and injections of an anterograde tracer, biotinylated dextran amine (BDA), into the deep layers of the superior colliculus produced the following results: (1) Retrogradely CTB-labeled neurons were found throughout SG, predominantly in its rostral part. CTB-labeled neurons were also found in other cortical areas such as the visual cortex, the auditory cortex, the parietal association cortex, and the perirhinal cortex. (2) Anterogradely BDA-labeled axons and their terminals were also observed throughout SG. Dual visualization of BDA and CTB showed that retrogradely labeled SG neurons and anterogradely labeled tectal axon terminal boutons overlapped considerably in the rostral part of SG, and their direct synaptic contacts were also confirmed via electron microscopy. These findings suggest that multimodal information from the superior colliculus can be processed directly in SG neurons projecting to Te2D.

  15. Neuron types in the rat dorsal lateral geniculate nucleus identified in Nissl and deimpregnated Golgi preparations.

    PubMed

    Werner, L; Brauer, K

    1984-01-01

    To identify geniculo-cortical relay neurons (GCR-neurons) and interneurons (I-neurons) in Nissl stained sections of the albino rat's (Wistar strain) dorsal lateral geniculate nucleus (dLGN) we combined a Golgi deimpregnation technique (Fairén et al. 1977) with the Nissl staining. The two types of neurons show numerous characteristic features in Golgi preparations (Brauer and Schober 1973, Grossman et al. 1973, Brauer et al. 1974, Winkelmann et al. 1976, 1979). After application of the combined method it is obvious that neuronal somata exhibit also features which make it possible to identify these types of neurons in Nissl stained series. GCR-neurons are characterized by a very broad cytoplasmic portion, whereas a particularly thin cytoplasm rim is typical of I-neurons. Our findings confirm former results obtained by analysis of Nissl material (Werner and Kruger 1973, Werner et al. 1975, Werner and Winkelmann 1976, Werner et al. 1984). In these investigations, special attention was paid to cytoplasmic and nuclear characteristics in order to elucidate the ratio of GCR-/I-neurons (13:1) and the internal dLGN topography. It is still discussed if the described cytological features can be taken as basis for the classification of GCR- and I-neurons in other species.

  16. Mercury in the dorsal root ganglia of rats treated with inorganic or organic mercury

    SciTech Connect

    Schioenning, J.D.; Moeller-Madsen, B.; Danscher, G. )

    1991-10-01

    Autometallographic silver amplification has been used to demonstrate the localization of mercury deposits in rat dorsal root ganglia after repeated intraperitoneal injections of mercuric chloride or methylmercuric chloride. The silver-enhanced mercury deposits were demonstrated with the light and electron microscope. The degree of intracellular staining of the individual cells depended on the mercury compound and total dosage. Ganglion cells (types A and B) and macrophages were found to accumulate mercury after a total dosage of 400 {mu}g HgCl{sub 2}. After 600 {mu}g HgCl{sub 2}, satellite cells, endothelial cells and fibroblasts were additionally found to contain mercury deposits. Treatment with 6,000 {mu}g CH{sub 3}HgCl caused faint staining of type A and B ganglion cells and fibroblasts. Macrophages, however, were the most heavily stained cells after treatment with CH{sub 3}HgCl. Ultrastructurally, mercury was exclusively located in lysosomes. This was irrespective of the cell type and mercury compound used for treatment.

  17. Effect of paclitaxel on transient receptor potential vanilloid 1 in rat dorsal root ganglion.

    PubMed

    Hara, Tomomi; Chiba, Terumasa; Abe, Kenji; Makabe, Akiko; Ikeno, Souichi; Kawakami, Kazuyoshi; Utsunomiya, Iku; Hama, Toshihiro; Taguchi, Kyoji

    2013-06-01

    Peripheral neuropathy is a common adverse effect of paclitaxel treatment. To analyze the contribution of transient receptor potential vanilloid 1 (TRPV1) in the development of paclitaxel-induced thermal hyperalgesia, TRPV1 expression in the rat dorsal root ganglion (DRG) was analyzed after paclitaxel treatment. Behavioral assessment using the tail-flick test showed that intraperitoneal administration of 2 and 4 mg/kg paclitaxel induced thermal hyperalgesia after days 7, 14, and 21. Paclitaxel-induced thermal hyperalgesia after day 14 was significantly inhibited by the TRP antagonist ruthenium red (3 mg/kg, s.c.) and the TRPV1 antagonist capsazepine (30 mg/kg, s.c.). Paclitaxel (2 and 4 mg/kg) treatment increased the expression of TRPV1 mRNA and protein in DRG neurons. Immunohistochemistry showed that paclitaxel (4 mg/kg) treatment increased TRPV1 protein expression in small and medium DRG neurons 14 days after treatment. Antibody double labeling revealed that isolectin B4-positive small DRG neurons co-expressed TRPV1. TRPV1 immunostaining was up-regulated in paw skin day 14 after paclitaxel treatment. Moreover, in situ hybridization histochemistry revealed that most of the TRPV1 mRNA-labeled neurons in the DRG were small or medium in size. These results suggest that paclitaxel treatment increases TRPV1 expression in DRG neurons and may contribute to functional peripheral neuropathic pain.

  18. Chronic NGF treatment induces somatic hyperexcitability in cultured dorsal root ganglion neurons of the rat.

    PubMed

    Kayano, Tomohiko; Kitamura, Naoki; Moriya, Taiki; Kuwahara, Takeshi; Komagiri, You; Toescu, Emil C; Shibuya, Izumi

    2013-01-01

    Adult rat dorsal root ganglion (DRG) neurons cultured in the presence of 100-ng/mL NGF were reported to show spontaneous action potentials in the cell-attached recording. In this study, underlying mechanisms were examined in the whole-cell and outside-out voltage clamp recording. In 75% neurons with on-cell firing, transient inward current spikes were repetitively recorded in the voltage clamp mode at -50 mV in the whole-cell configuration (named "Isp"). Isp with stable amplitudes occurred in an all-or-none fashion, and was abolished by TTX (< 100 nM), lidocaine (< 1 mM) and a reduction of extracellular Na(+) (154 to 100 mM) in an all-or-none fashion, suggesting that Isp reflects spontaneous dicharges occurring at the loosely voltage-clamped regions. Isp was also observed in the excised outside-out patches and the kinetics and the sensitivity to TTX and lidocaine resembled those in the whole-cell. Spontaneous action potentials were also recorded in the current clamp mode. Small subthreshold spikes often preceded the action potentials. When the localized discharge affected a whole-somatic membrane potential to overcome a threshold, the action potential generated. These results indicate that the triggering sources of the action potential exist in the somatic membrane itself in NGF-treated DRG neurons.

  19. 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.

  20. Dynamic properties of corticogeniculate excitatory transmission in the rat dorsal lateral geniculate nucleus in vitro

    PubMed Central

    Granseth, Björn

    2004-01-01

    The feedback excitation from the primary visual cortex to principal cells in the dorsal lateral geniculate nucleus (dLGN) is markedly enhanced with firing frequency. This property presumably reflects the ample short-term plasticity at the corticogeniculate synapse. The present study aims to explore corticogeniculate excitatory postsynaptic currents (EPSCs) evoked by brief trains of stimulation with whole-cell patch-clamp recordings in dLGN slices from DA-HAN rats. The EPSCs rapidly increased in amplitude with the first two or three impulses followed by a more gradual growth. A double exponential function with time constants 39 and 450 ms empirically described the growth for 5–25Hz trains. For lower train frequencies (down to 1Hz) a third component with time constant 4.8 s had to be included. The different time constants are suggested to represent fast and slow components of facilitation and augmentation. The time constant of the fast component changed with the extracellular calcium ion concentration as expected for a facilitation mechanism involving an endogenous calcium buffer that is more efficiently saturated with larger calcium influx. Concerning the function of the corticogeniculate feedback pathway, the different components of short-term plasticity interacted to increase EPSC amplitudes on a linear scale to firing frequency in the physiological range. This property makes the corticogeniculate synapse well suited to function as a neuronal amplifier that enhances the thalamic transfer of visual information to the cortex. PMID:14724201

  1. Exaggerated C-fiber activation prevents peripheral nerve injury-induced hyperinducibility of c-Fos in partially deafferented spinal dorsal horn.

    PubMed

    Sugimoto, T; Funahashi, M; Xiao, C; Adachi, A; Ichikawa, H

    1997-02-01

    Dorsal horn neurons chronically deafferented by peripheral nerve injuries acquire hypersensitivity to noxious input from outside the original receptive field. This study examines the effect of electrical nerve stimulation at the time of injury on such injury-induced hypersensitivity. The medial 3/8 of the dorsal horn laminae I/II around the junction of 4th and 5th lumbar segments (the tibial territory) was deafferented by transection of the ipsilateral tibial nerve in rats. At 2 days or 3 weeks postinjury, the hindpaw was injected with formalin to induce c-fos. At 2 days, neurons with induced c-Fos protein-like immunoreactivity (fos-neurons) were largely confined in the lateral 5/8 of laminae I/II (the peroneal and hip, thus P and H territory). At 3 weeks, fos-neurons significantly increased in the deafferented tibial territory. A similar increase was also noted in the P and H territory. Thus the dorsal horn neurons exhibited c-fos hyperinducibility, an indication of hypersensitivity. Electrical stimulation with a train of 150 shocks (10 V, 2 ms) of the proximal nerve stump immediately after transection prevented the c-fos hyperinducibility. The effect was greater with the stimulation frequency of 0.5 Hz than 0.1 Hz or 10 Hz. The stimulation had no effect on the c-fos inducibility at 2 days postinjury.

  2. Hyperexcitability in Spinal WDR Neurons following Experimental Disc Herniation Is Associated with Upregulation of Fractalkine and Its Receptor in Nucleus Pulposus and the Dorsal Root Ganglion

    PubMed Central

    Moen, Aurora; Haugen, Fred; Gjerstad, Johannes

    2016-01-01

    Introduction. Lumbar radicular pain following intervertebral disc herniation may be associated with a local inflammatory response induced by nucleus pulposus (NP) cells. Methods. In anaesthetized Lewis rats, extracellular single unit recordings of wide dynamic range (WDR) neurons in the dorsal horn and qPCR were used to explore the effect of NP application onto the dorsal nerve roots (L3–L5). Results. A clear increase in C-fiber response was observed following NP conditioning. In the NP tissue, the expression of interleukin-1β (IL-1β), colony stimulating factor 1 (Csf1), fractalkine (CX3CL1), and the fractalkine receptor CX3CR1 was increased. Minocycline, an inhibitor of microglial activation, inhibited the increase in neuronal activity and attenuated the increase in IL-1β, Csf1, CX3L1, and CX3CR1 expression in NP tissue. In addition, the results demonstrated an increase in the expression of TNF, CX3CL1, and CX3CR1 in the dorsal root ganglions (DRGs). Conclusion. Hyperexcitability in the pain pathways and the local inflammation after disc herniation may involve upregulation of CX3CL1 signaling in both the NP and the DRG. PMID:28116212

  3. Expression of adrenomedullin in rats after spinal cord injury and intervention effect of recombinant human erythropoietin.

    PubMed

    Zhao, Liang; Jing, Yu; Qu, Lin; Meng, Xiangwei; Cao, Yang; Tan, Huibing

    2016-12-01

    The expression of adrenomedullin (ADM) in injured tissue of rat spinal cord was observed and the effect of recombinant human erythropoietin was analyzed. A total of 45 Sprague-Dawley rats were selected and divided into 3 equal groups including, a sham-operation group in which rats received an excision of vertebral plate; a spinal cord injury model group and a recombinant human erythropoietin group in which rats with spinal cord injury received a caudal vein injection of 300 units recombinant human erythropoietin after injury. Hematoxylin and eosin staining was performed to observe the spinal cord injury conditions. Immunohistochemical staining was performed to observe the expression of ADM. Pathologic changes in the group of recombinant human erythropoietin at various times were significantly less severe than those in the group of spinal cord injury model. The expression of ADM was increased particularly in the group of recombinant human erythropoietin (P<0.01). The improved Tarlov scores of the group of spinal cord injury model and the group of recombinant human erythropoietin were lower than those of the sham-operation group at 3, 6 and 9 days (P<0.01). Thus, the recombinant human erythropoietin is capable of alleviating the secondary injury of spinal cord. One of the mechanisms may be achieved by promoting the increase of ADM expression.

  4. Expression of adrenomedullin in rats after spinal cord injury and intervention effect of recombinant human erythropoietin

    PubMed Central

    Zhao, Liang; Jing, Yu; Qu, Lin; Meng, Xiangwei; Cao, Yang; Tan, Huibing

    2016-01-01

    The expression of adrenomedullin (ADM) in injured tissue of rat spinal cord was observed and the effect of recombinant human erythropoietin was analyzed. A total of 45 Sprague-Dawley rats were selected and divided into 3 equal groups including, a sham-operation group in which rats received an excision of vertebral plate; a spinal cord injury model group and a recombinant human erythropoietin group in which rats with spinal cord injury received a caudal vein injection of 300 units recombinant human erythropoietin after injury. Hematoxylin and eosin staining was performed to observe the spinal cord injury conditions. Immunohistochemical staining was performed to observe the expression of ADM. Pathologic changes in the group of recombinant human erythropoietin at various times were significantly less severe than those in the group of spinal cord injury model. The expression of ADM was increased particularly in the group of recombinant human erythropoietin (P<0.01). The improved Tarlov scores of the group of spinal cord injury model and the group of recombinant human erythropoietin were lower than those of the sham-operation group at 3, 6 and 9 days (P<0.01). Thus, the recombinant human erythropoietin is capable of alleviating the secondary injury of spinal cord. One of the mechanisms may be achieved by promoting the increase of ADM expression. PMID:28101163

  5. Passive immunization with LINGO-1 polyclonal antiserum afforded neuroprotection and promoted functional recovery in a rat model of spinal cord injury.

    PubMed

    Lv, Jun; Xu, Ru-xiang; Jiang, Xiao-dan; Lu, Xin; Ke, Yi-quan; Cai, Ying-qian; Du, Mou-xuan; Hu, Changchen; Zou, Yu-xi; Qin, Ling-sha; Zeng, Yan-jun

    2010-01-01

    LINGO-1 (leucine-rich repeat and Ig domain-containing, Nogo receptor-interacting protein) is an important component of the NgR receptor complex involved in RhoA activation and axon regeneration. The authors report on passive immunization with LINGO-1 polyclonal antiserum, a therapeutic approach to overcome NgR-mediated growth inhibition after spinal cord injury (SCI). The intrathecally administered high-titer rabbit-derived antiserum can be detected around the injury site within a wide time window; it blocks LINGO-1 in vivo with high molecular specificity. In this animal model, passive immunization with LINGO-1 antiserum significantly decreased RhoA activation and increased neuronal survival. Adult rats immunized in this manner show recovery of certain hindlimb motor functions after dorsal hemisection of the spinal cord. Thus, passive immunotherapy with LINGO-1 polyclonal antiserum may represent a promising repair strategy following acute SCI.

  6. 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

  7. Electrophysiological mapping of rat sensorimotor lumbosacral spinal networks after complete paralysis.

    PubMed

    Gad, Parag; Roy, Roland R; Choe, Jaehoon; Zhong, Hui; Nandra, Mandheeraj Singh; Tai, Yu-Chong; 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 chapter, 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 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.

  8. Neuron type-specific effects of brain-derived neurotrophic factor in rat superficial dorsal horn and their relevance to ‘central sensitization’

    PubMed Central

    Lu, Van B; Ballanyi, Klaus; Colmers, William F; Smith, Peter A

    2007-01-01

    Chronic constriction injury (CCI) of the rat sciatic nerve increases the excitability of the spinal dorsal horn. This ‘central sensitization’ leads to pain behaviours analogous to human neuropathic pain. We have established that CCI increases excitatory synaptic drive to putative excitatory, ‘delay’ firing neurons in the substantia gelatinosa but attenuates that to putative inhibitory, ‘tonic’ firing neurons. Here, we use a defined-medium organotypic culture (DMOTC) system to investigate the long-term actions of brain-derived neurotrophic factor (BDNF) as a possible instigator of these changes. The age of the cultures and their 5–6 day exposure to BDNF paralleled the protocol used for CCI in vivo. Effects of BDNF (200 ng ml−1) in DMOTC were reminiscent of those seen with CCI in vivo. These included decreased synaptic drive to ‘tonic’ neurons and increased synaptic drive to ‘delay’ neurons with only small effects on their membrane excitability. Actions of BDNF on ‘delay’ neurons were exclusively presynaptic and involved increased mEPSC frequency and amplitude without changes in the function of postsynaptic AMPA receptors. By contrast, BDNF exerted both pre- and postsynaptic actions on ‘tonic’ cells; mEPSC frequency and amplitude were decreased and the decay time constant reduced by 35%. These selective and differential actions of BDNF on excitatory and inhibitory neurons contributed to a global increase in dorsal horn network excitability as assessed by the amplitude of depolarization-induced increases in intracellular Ca2+. Such changes and their underlying cellular mechanisms are likely to contribute to CCI-induced ‘central sensitization’ and hence to the onset of neuropathic pain. PMID:17761774

  9. Protein kinase C gamma interneurons in the rat medullary dorsal horn: distribution and synaptic inputs to these neurons, and subcellular localization of the enzyme.

    PubMed

    Peirs, Cédric; Patil, Sudarshan; Bouali-Benazzouz, Rabia; Artola, Alain; Landry, Marc; Dallel, Radhouane

    2014-02-01

    The γ isoform of protein kinase C (PKCγ), which is concentrated in interneurons in the inner part of lamina II (IIi ) of the dorsal horn, has been implicated in the expression of tactile allodynia. Lamina IIi PKCγ interneurons were shown to be activated by tactile inputs and to participate in local circuits through which these inputs can reach lamina I, nociceptive output neurons. That such local circuits are gated by glycinergic inhibition and that A- and C-fibers low threshold mechanoreceptors (LTMRs) terminate in lamina IIi raise the general issue of synaptic inputs to lamina IIi PKCγ interneurons. Combining light and electron microscopic immunochemistry in the rat spinal trigeminal nucleus, we show that PKCγ-immunoreactivity is mostly restricted to interneurons in lamina IIi of the medullary dorsal horn, where they constitute 1/3 of total neurons. The majority of synapses on PKCγ-immunoreactive interneurons are asymmetric (likely excitatory). PKCγ-immunoreactive interneurons appear to receive exclusively myelinated primary afferents in type II synaptic glomeruli. Neither large dense core vesicle terminals nor type I synaptic glomeruli, assumed to be the endings of unmyelinated nociceptive terminals, were found on these interneurons. Moreover, there is no vesicular glutamate transporter 3-immunoreactive bouton, specific to C-LTMRs, on PKCγ-immunoreactive interneurons. PKCγ-immunoreactive interneurons contain GABAA ergic and glycinergic receptors. At the subcellular level, PKCγ-immunoreactivity is mostly concentrated on plasma membranes, close to, but not within, postsynaptic densities. That only myelinated primary afferents were found to contact PKCγ-immunoreactive interneurons suggests that myelinated, but not unmyelinated, LTMRs play a critical role in the expression of mechanical allodynia.

  10. Attenuation of hyperalgesia responses via the modulation of 5-hydroxytryptamine signalings in the rostral ventromedial medulla and spinal cord in a 6-hydroxydopamine-induced rat model of Parkinson’s disease

    PubMed Central

    Wang, Chen-Tao; Mao, Cheng-Jie; Zhang, Xiao-Qi; Zhang, Cai-Yi; Lv, Dong-Jun; Yang, Ya-Ping; Xia, Kai-Lin; Liu, Jun-Yi; Wang, Fen; Hu, Li-Fang; Xu, Guang-Yin

    2017-01-01

    Background Although pain is one of the most distressing non-motor symptoms among patients with Parkinson’s disease, the underlying mechanisms of pain in Parkinson’s disease remain elusive. The aim of the present study was to investigate the role of serotonin (5-hydroxytryptamine) in the rostral ventromedial medulla (RVM) and spinal cord in pain sensory abnormalities in a 6-hydroxydopamine-treated rat model of Parkinson’s disease. Methods The rotarod test was used to evaluate motor function. The radiant heat test and von Frey test were conducted to evaluate thermal and mechanical pain thresholds, respectively. Immunofluorescence was used to examine 5-hydroxytryptamine neurons and fibers in the rostral ventromedial medulla and spinal cord. High-performance liquid chromatography was used to determine 5-hydroxytryptamine and 5-hydroxyindoleacetic acid levels. Results The duration of running time on the rotarod test was significantly reduced in 6-hydroxydopamine-treated rats. Nociceptive thresholds of both mechanical and heat pain were reduced compared to sham-treated rats. In addition to the degeneration of cell bodies and fibers in the substantia nigra pars compacta, the number of rostral ventromedial medulla 5-hydroxytryptamine neurons and 5-hydroxytryptamine fibers in the spinal dorsal horn was dramatically decreased. 5-Hydroxytryptamine concentrations in both the rostral ventromedial medulla and spinal cord were reduced. Furthermore, the administration of citalopram significantly attenuated pain hypersensitivity. Interestingly, Intra-rostral ventromedial medulla (intra-RVM) microinjection of 5,7-dihydroxytryptamine partially reversed pain hypersensitivity of 6-hydroxydopamine-treated rats. Conclusions These results suggest that the decreased 5-hydroxytryptamine contents in the rostral ventromedial medulla and spinal dorsal horn may be involved in hyperalgesia in the 6-hydroxydopamine-induced rat model of Parkinson’s disease. PMID:28326933

  11. Upregulated TLR3 Promotes Neuropathic Pain by Regulating Autophagy in Rat With L5 Spinal Nerve Ligation Model.

    PubMed

    Chen, Weijia; Lu, Zhijun

    2016-12-21

    Microglia, rapidly activated following peripheral nerve injury (PNI), accumulate within the spinal cord and adopt inflammation that contributes to development and maintenance of neuropathic pain. Microglia express functional Toll-like receptors (TLRs), which play pivotal roles in regulating inflammatory processes. However, little is known about the role of TLR3 in regulating neuropathic pain after PNI. Here TLR3 expression and autophagy activation was assayed in dorsal root ganglions and in microglia following PNI by using realtime PCR, western blot and immunohistochemistry. The role of TLR3/autophagy signaling in regulating tactile allodynia was evaluated by assaying paw mechanical withdrawal threshold and cold allodynia after intrathecal administration of Poly (I:C) and 3-methyladenine (3-MA). We found that L5 spinal nerve ligation (SNL) induces the expression of TLR3 in dorsal root ganglions and in primary rat microglia at the mRNA and protein level. Meanwhile, L5 SNL results in an increased activation of autophagy, which contributes to microglial activation and subsequent inflammatory response. Intrathecal administration of Poly (I:C), a TLR3 agonist, significantly increases the activation of microglial autophagy, whereas TLR3 knockdown markedly inhibits L5 SNL-induced microglial autophagy. Poly (I:C) treatment promotes the expression of proinflammatory mediators, whereas 3-MA (a specific inhibitor of autophagy) suppresses Poly (I:C)-induced secretion of proinflammatory cytokines. Autophagy inhibition further inhibits TLR3-mediated mechanical and cold hypersensitivity following SNL. These results suggest that inhibition of TLR3/autophagy signaling contributes to alleviate neurophathic pain triggered by SNL.

  12. Differential Histopathological and Behavioral Outcomes Eight Weeks after Rat Spinal Cord Injury by Contusion, Dislocation, and Distraction Mechanisms

    PubMed Central

    Chen, Kinon; Liu, Jie; Assinck, Peggy; Bhatnagar, Tim; Streijger, Femke; Zhu, Qingan; Dvorak, Marcel F.; Kwon, Brian K.; Tetzlaff, Wolfram

    2016-01-01

    Abstract The objective of this study was to compare the long-term histological and behavioral outcomes after spinal cord injury (SCI) induced by one of three distinct biomechanical mechanisms: dislocation, contusion, and distraction. Thirty male Sprague-Dawley rats were randomized to incur a traumatic cervical SCI by one of these three clinically relevant mechanisms. The injured cervical spines were surgically stabilized, and motor function was assessed for the following 8 weeks. The spinal cords were then harvested for histologic analysis. Quantification of white matter sparing using Luxol fast blue staining revealed that dislocation injury caused the greatest overall loss of white matter, both laterally and along the rostrocaudal axis of the injured cord. Distraction caused enlarged extracellular spaces and structural alteration in the white matter but spared the most myelinated axons overall. Contusion caused the most severe loss of myelinated axons in the dorsal white matter. Immunohistochemistry for the neuronal marker NeuN combined with Fluoro Nissl revealed that the dislocation mechanism resulted in the greatest neuronal cell losses in both the ventral and dorsal horns. After the distraction injury mechanism, animals displayed no recovery of grip strength over time, in contrast to the animals subjected to contusion or dislocation injuries. After the dislocation injury mechanism, animals displayed no improvement in the grooming test, in contrast to the animals subjected to contusion or distraction injuries. These data indicate that different SCI mechanisms result in distinct patterns of histopathology and behavioral recovery. Understanding this heterogeneity may be important for the future development of therapeutic interventions that target specific neuropathology after SCI. PMID:26671448

  13. Dwarf with dual spinal kyphotic deformity at the cervical and dorsal spine unassociated with odontoid hypoplasia: Surgical management

    PubMed Central

    Satyarthee, Guru Dutta; Mankotia, Dipanker Singh

    2016-01-01

    Morquio's syndrome is associated with systemic skeletal hypoplasia leading to generalized skeletal deformation. The hypoplasia of odontoid process is frequent association, which is responsible for atlantoaxial dislocation causing compressive myelopathy. However, development of sub-axial cervical kyphotic deformity unassociated with odontoid hypoplasia is extremely rare, and coexistence of dorsal kyphotic deformity is not reported in the western literature till date and represents first case. Current case is 16-year-old boy, who presented with severe kyphotic deformity of cervical spine with spastic quadriparesis. Interestingly, he also had additional asymptomatic kyphotic deformity of dorsal spine; however, odontoid proves hypoplasia was not observed. He was only symptomatic for cervical compression, accordingly surgery was planned. The patient was planned for correction of cervical kyphotic deformity under general anesthesia, underwent fourth cervical corpectomy with resection of posterior longitudinal ligament and fusion with autologous bone graft derived from right fibula, which was refashioned approximating to the width of the corpectomy size after harvesting and fixed between C3 and C5 vertebral bodies and further secured with anterior cervical plating. He tolerated surgical procedure well with improvement in power with significant reduction in spasticity. Postoperative X-ray, cervical spine revealed complete correction of kyphotic deformity cervical spine. At follow-up 6 months following surgery, he is doing well. Successful surgical correction of symptomatic cervical kyphotic deformity can be achieved utilizing anterior cervical corpectomy, autologous fibular bone graft, and anterior cervical plating. PMID:27857796

  14. Systematic analysis of axonal damage and inflammatory response in different white matter tracts of acutely injured rat spinal cord.

    PubMed

    Gomes-Leal, W; Corkill, D J; Picanço-Diniz, C W

    2005-12-20

    The mechanisms of white matter (WM) damage during secondary degeneration are a fundamental issue in the pathophysiology of central nervous system (CNS) diseases. Our main goal was to describe the pattern of an acute inflammatory response and secondary damage to axons in different WM tracts of acutely injured rat spinal cord. Adult rats were deeply anesthetized and injected with 20 nmol of NMDA into the spinal cord ventral horn on T7. Animals were perfused after survival times of 1 day, 3 days and 7 days. Ten micrometer sections were submitted to immunocytochemical analysis for activated macrophages/microglia, neutrophils and damaged axons. There were inflammatory response and progressive tissue destruction of ventral WM (VWM) with formation of microcysts in both VWM and lateral WM (LWM). In the VWM, the number of beta-amyloid precursor protein (beta-APP) end-bulbs increased from 1 day with a peak at 3 days, decreasing by 7 days following the injection. APP end-bulbs were present in the dorsal WM (DWM) at 3 days survival time but were not in the LWM. Electron microscopic analysis revealed different degrees of myelin disruption and axonal pathology in the vacuolated WM up to 14 mm along the rostrocaudal axis. Quantitative analysis revealed a significant loss of medium and large axons (P < 0.05), but not of small axons (P > 0.05). Our results suggest that bystander axonal damage and myelin vacuolation are important secondary component of the pathology of WM tracts following rat SCI. Further studies are needed to understand the mechanisms of these pathological events.

  15. Therapeutic Effect of Epidurally Administered Lipo-Prostaglandin E1 Agonist in a Rat Spinal Stenosis Model

    PubMed Central

    Park, Sang Hyun; Choe, Ghee Young; Moon, Jee Yeon; Nahm, Francis Sahngun; Kim, Yong Chul

    2014-01-01

    Background A lipo-prostaglandin E1 agonist is effective for the treatment of neurological symptoms of spinal stenosis when administered by an oral or intravenous route. we would like to reveal the therapeutic effect of an epidural injection of lipo-prostaglandin E1 on hyperalgesia in foraminal stenosis. Methods A total of 40 male Sprague-Dawley rats were included. A small stainless steel rod was inserted into the L5/L6 intervertebral foramen to produce intervertebral foraminal stenosis and chronic compression of the dorsal root ganglia (DRG). The rats were divided into three groups: epidural PGE1 (EP) (n = 15), saline (n = 15), and control (n = 10). In the EP group, 0.15 µg.kg-1 of a lipo-PGE1 agonist was injected daily via an epidural catheter for 10 days from postoperative day 3. In the saline group, saline was injected. Behavioral tests for mechanical hyperalgesia were performed for 3 weeks. Then, the target DRG was analyzed for the degree of chromatolysis, chronic inflammation, and fibrosis in light microscopic images. Results From the fifth day after lipo-PGE1 agonist injection, the EP group showed significant recovery from mechanical hyperalgesia, which was maintained for 3 weeks (P < 0.05). Microscopic analysis showed much less chromatolysis in the EP group than in the saline or control groups. Conclusions An epidurally administered lipo-PGE1 agonist relieved neuropathic pain, such as mechanical hyperalgesia, in a rat foraminal stenosis model, with decreasing chromatolysis in target DRG. We suggest that epidurally administered lipo-PGE1 may be a useful therapeutic candidate for patients with spinal stenosis. PMID:25031807

  16. CYTOLOGICAL STUDIES OF ORGANOTYPIC CULTURES OF RAT DORSAL ROOT GANGLIA FOLLOWING X-IRRADIATION IN VITRO

    PubMed Central

    Masurovsky, Edmund B.; Bunge, Mary Bartlett; Bunge, Richard P.

    1967-01-01

    Under suitable conditions rat dorsal root ganglia differentiate and myelinate in culture, providing an organotypic model of the ganglion (8). Mature cultures of this type were irradiated with a 40 kR dose of 184 kvp X-rays and, after daily observation in the living state, were fixed for light and electron microscopy. Within 24 hr after irradiation, numerous Schwann cells investing unmyelinated axons acutely degenerate. The axons thus denuded display little change. Conversely, few ultrastructural changes develop in Schwann cells investing myelinated axons until after the 4th day. During the 4–14 day period, these Schwann cells and their related myelin sheaths undergo progressive deterioration. Associated axons decrease in diameter but are usually maintained. Myelin deterioration begins as a nodal lengthening and then progresses along two different routes. In intact Schwann cells, fragmentation of myelin begins in a pattern reminiscent of Wallerian degeneration, but its slow breakdown thereafter suggests metabolic disturbances in these Schwann cells. The second pattern of myelin deterioration, occurring after complete degeneration of the related Schwann cell, involves unusual configurational changes in the myelin lamellae. Atypical repeating periods are formed by systematic splitting of lamellae at each major dense line with further splitting at the intraperiod line (Type I) or by splitting in the region of every other intraperiod line (Type II); some sheaths display a compact, wavy, inner zone and an abnormally widened lamellar spacing peripherally (Type III). Extensive blebbing of myelin remnants characterizes the final stages of this extracellular myelin degradation. These observations provide the first description of ultrastructural changes produced by ionizing radiation in nerve fascicles in vitro. PMID:10976235

  17. CYTOLOGICAL STUDIES OF ORGANOTYPIC CULTURES OF RAT DORSAL ROOT GANGLIA FOLLOWING X-IRRADIATION IN VITRO

    PubMed Central

    Masurovsky, Edmund B.; Bunge, Mary Bartlett; Bunge, Richard P.

    1967-01-01

    Long-term organotypic cultures of rat dorsal root ganglia were exposed to a single 40 kR dose of 184 kvp X-rays and studied in the living and fixed states by light or electron microscopy at 1–14 day intervals thereafter. Within the first 4 days following irradiation, over 30% of the neurons display chromatolytic reactions (eccentric nuclei, peripheral dispersal of Nissl substance, central granular zone) as well as abnormal nucleolar changes and dissociation of ribosomes from endoplasmic reticulum cisternae. Some satellite cells undergo retraction or acute degeneration, leaving only basement membrane to cover the neuron in these areas. 8 days after irradiation, neurons also exhibit (a) areas in which ribosomes are substantially reduced, (b) regions of cytoplasmic sequestration, (c) extensive vacuolization of granular endoplasmic reticulum and Golgi complex, and (d) diversely altered mitochondria (including the presence of ribosome-like particles or association with abnormal glycogen and lipid deposits). Nucleolar components become altered or reoriented and may form abnormal projections and ringlike configurations. Sizeable areas of the neuronal soma are now denuded of satellite cells; underlying these areas, nerve processes are found abnormally invaginated into the neuronal cytoplasm. By the 14th day following irradiation, most neurons display marked degenerative changes including extensive regions of ribosome depletion, sequestration, vacuolization, autolysis, and, in some areas, swirls of filaments, myelin figures, and heterogeneous dense bodies. These observations demonstrate that X-irradiation produces profound cytopathological changes in nervous tissue isolated from the host and that many of these changes resemble the effects of radiation on nervous tissue in vivo. PMID:10976234

  18. 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.

  19. The effects of age on the morphometry of the cervical spinal cord and spinal column in adult rats: an MRI-based study.

    PubMed

    Laing, Andrew C; Brenneman, Elora C; Yung, Andrew; Liu, Jie; Kozlowski, Piotr; Oxland, Thomas

    2014-10-01

    Rat models are commonly used to investigate the pathophysiological pathways and treatment outcomes after spinal cord injury (SCI). The high incidence of fall-induced SCI in older adults has created a need for aging models of SCI in rats to investigate potential age-related differences in SCI severity and outcomes. The aims of this study were to determine the influences of age and vertebral level on the geometries of the cervical spinal cord and spinal column in a rat model. Three young (3 months) and three aged (12 months) Fischer 344 rats were imaged in a high field (7 T) small-animal magnetic resonance imaging system. All spinal cord geometry variables (including depth, width, and axial cross-sectional area) and one spinal canal variable (depth) were significantly larger in the aged specimens by an average of 8.1%. There were main effects of vertebral level on all spinal cord variables and four spinal canal variables with values generally larger at C4 as compared to C6 (average increases ranged from 5.7% to 12.9% in spinal cord measures and 5.4% to 6.8% in spinal canal measures). High inter-rater reliability between two measurers was observed with a mean intraclass correlation of 0.921 and percent difference of 0.9% across all variables measured. This study clearly demonstrates that cervical spinal cord geometry changes between the ages of 3 and 12 months in Fischer 344 rats. This information can aid in the planning and interpretation of studies that use a rat model to investigate the influence of age on cervical SCI.

  20. The expression of contextual fear conditioning involves activation of a NMDA receptor-nitric oxide-cGMP pathway in the dorsal hippocampus of rats.

    PubMed

    Fabri, Denise R S; Hott, Sara C; Reis, Daniel G; Biojone, Caroline; Corrêa, Fernando M A; Resstel, Leonardo B M

    2014-10-01

    The dorsal portion of the hippocampus is a limbic structure that is involved in fear conditioning modulation in rats. Moreover, evidence shows that the local dorsal hippocampus glutamatergic system, nitric oxide (NO) and cGMP modulate behavioral responses during aversive situations. Therefore, the present study investigated the involvement of dorsal hippocampus NMDA receptors and the NO/cGMP pathway in contextual fear conditioning expression. Male Wistar rats were submitted to an aversive contextual conditioning session and 48 h later they were re-exposed to the aversive context in which freezing, cardiovascular responses (increase of both arterial pressure and heart rate) and decrease of tail temperature were recorded. The intra-dorsal hippocampus administration of the NMDA receptor antagonist AP7, prior to the re-exposure to the aversive context, attenuated fear-conditioned responses. The re-exposure to the context evoked an increase in NO concentration in the dorsal hippocampus of conditioned animals. Similar to AP7 administration, we observed a reduction of contextual fear conditioning after dorsal hippocampus administration of either the neuronal NO synthase inhibitor N-propyl-L-arginine, the NO scavenger c-PTIO or the guanylate cyclase inhibitor ODQ. Therefore, the present findings suggest the possible existence of a dorsal hippocampus NMDA/NO/cGMP pathway modulating the expression of contextual fear conditioning in rats.

  1. 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.

  2. 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

  3. A combined electrophysiological and morphological study of neuropeptide Y-expressing inhibitory interneurons in the spinal dorsal horn of the mouse.

    PubMed

    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

    2016-03-01

    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.

  4. Force-dependent development of neuropathic central pain and time-related CCL2/CCR2 expression after graded spinal cord contusion injuries of the rat.

    PubMed

    Knerlich-Lukoschus, Friederike; Juraschek, Mathias; Blömer, Ulrike; Lucius, Ralph; Mehdorn, Hubertus M; Held-Feindt, Janka

    2008-05-01

    Spinal cord injury (SCI) often results in intractable chronic central pain syndromes. Recently chemokines such as CCL2 were identified as possible key integrators of neuropathic pain and inflammation after peripheral nerve lesion. The focus of the current study was the investigation of time-dependent CCL2 and CCR2 expression in relation to central neuropathic pain development after spinal cord impact lesions of 100, 150, or 200 kdyn force on spinal cord level T9 in adult rats. Below-level pain was monitored with weekly sensory testing for 42 days after SCI. In parallel expression of CCL2/CCR2 on cervical, thoracic, and lumbar levels was investigated by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry early (7 days [7d]), intermediate (15d), and late (42d) after lesion. Cellular source and anatomical pain related expression was determined by double-immunohistochemistry. Force-defined SCI led to acute mechanical hypersensitivity in all lesion groups, and to persistent below-level pain in severely injured animals. While in the early post-operative time course, CCL2 and CCR2 were expressed in astroglia and granulocytes only on level T9; there was additional astroglial CCL2 expression in dorsal columns and dorsal horns above and below T9 of severely injured animals 42d after lesion. In dorsal horns (level L3-L5) of animals exhibiting chronic below-level pain CCL2 was co-expressed with transmitters and receptors that are involved in nociceptive processing like calcitonin gene-related peptide (CGRP), Substance-P, vanilloid-receptor-1, and its activated phosphorylated form. These data demonstrate lesion grade dependence of below-level pain development and suggest chemokines as potential candidates for integrating inflammation and central neuropathic pain after SCI.

  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. Effect of chronic administration of morphine on the gene expression level of sodium-dependent vitamin C transporters in rat hippocampus and lumbar spinal cord.

    PubMed

    Zarebkohan, Amir; Javan, Mohammad; Satarian, Leila; Ahmadiani, Abolhasan

    2009-07-01

    Chronic morphine leads to dependence, tolerance, and neural apoptosis. Vitamin C inhibits the withdrawal syndrome in morphine-dependent subjects and prevents apoptosis in experimental models. Sodium-dependent vitamin C transporter (SVCT) type-2 is the main transporter for carrying vitamin C into the brain and neural cells. The mechanism(s) by which vitamin C inhibits morphine dependence in not understood. SVCT activity determines the vitamin C availably within the nervous system. We have examined the alterations in the expression of SVCT1, SVCT2, and its splice variants in morphine-tolerant rats. Morphine (20 mg/kg) was injected twice/day to male rats for either 7 or 14 days. The development of analgesic tolerance was assessed using tail-flick test. Lumbar spinal cord and the hippocampus were isolated for RNA extraction. Semiquantitative reverse transcriptase-polymerase chain reaction method was used to assess the levels of gene expression. Administration of morphine for 7 or 14 days reduced the expression level of SVCT2 in both hippocampus and dorsal lumbar spinal cord of rats. SVCT2 expression was reduced in vitamin C-, and vitamin C combined with morphine-treated animals. Results did not show SVCT2 splice variation. SVCT1 did not express in control or morphine-treated rats. It seems that reduced expression level of SVCT2 might be involved in the development of morphine side effects such as tolerance and dependency.

  7. NR2B phosphorylation at tyrosine 1472 in spinal dorsal horn contributed to N-methyl-D-aspartate-induced pain hypersensitivity in mice.

    PubMed

    Li, Shuai; Cao, Jing; Yang, Xian; Suo, Zhan-Wei; Shi, Lei; Liu, Yan-Ni; Yang, Hong-Bin; Hu, Xiao-Dong

    2011-11-01

    Calcium influx via N-methyl-D-aspartate (NMDA)-subtype glutamate receptors (NMDARs) regulates the intracellular trafficking of NMDARs, leading to long-lasting modification of NMDAR-mediated synaptic transmission that is involved in development, learning, and synaptic plasticity. The present study investigated the contribution of such NMDAR-dependent synaptic trafficking in spinal dorsal horn to the induction of pain hypersensitivity. Our data showed that direct activation of NMDARs by intrathecal NMDA application elicited pronounced mechanical allodynia in intact mice, which was concurrent with a specific increase in the abundance of NMDAR subunits NR1 and NR2B at the postsynaptic density (PSD)-enriched fraction. Selective inhibition of NR2B-containing NMDARs (NR2BR) by ifenprodil dose dependently attenuated the mechanical allodynia in NMDA-injected mice, suggesting the importance of NR2BR synaptic accumulation in NMDA-induced pain sensitization. The NR2BR redistribution at synapses after NMDA challenge was associated with a significant increase in NR2B phosphorylation at Tyr1472, a catalytic site by Src family protein tyrosine kinases (SFKs) that has been shown to prevent NR2B endocytosis. Intrathecal injection of a specific SFKs inhibitor, PP2, to block NR2B tyrosine phosphorylation eliminated NMDA-induced NR2BR synaptic expression and also attenuated the mechanical allodynia. These data suggested that activation of spinal NMDARs was able to accumulate NR2BR at synapses via SFK signaling, which might exaggerate NMDAR-dependent nociceptive transmission and contribute to NMDA-induced nociceptive behavioral hyperresponsiveness.

  8. Early applied electric field stimulation attenuates secondary apoptotic responses and exerts neuroprotective effects in acute spinal cord injury of rats.

    PubMed

    Zhang, C; Zhang, G; Rong, W; Wang, A; Wu, C; Huo, X

    2015-04-16

    Injury potential, which refers to a direct current voltage between intact and injured nerve ends, is mainly caused by injury-induced Ca2+ influx. Our previous studies revealed that injury potential increased with the onset and severity of spinal cord injury (SCI), and an application of applied electric field stimulation (EFS) with the cathode distal to the lesion could delay and attenuate injury potential formation. As Ca2+ influx is also considered as a major trigger for secondary injury after SCI, we hypothesize that EFS would protect an injured spinal cord from secondary injury and consequently improve functional and pathological outcomes. In this study, rats were divided into three groups: (1) sham group, laminectomy only; (2) control group, subjected to SCI only; and (3) EFS group, received EFS immediately post-injury with the injury potential modulated to 0±0.5 mV by EFS. Functional recovery of the hind limbs was assessed using the Basso, Beattie, and Bresnahan (BBB) locomotor scale. Results revealed that EFS-treated rats exhibited significantly better locomotor function recovery. Luxol fast blue staining was performed to assess the spared myelin area. Immunofluorescence was used to observe the number of myelinated nerve fibers. Ultrastructural analysis was performed to evaluate the size of myelinated nerve fibers. Findings showed that the EFS group rats exhibited significantly less myelin loss and had larger and more myelinated nerve fibers than the control group rats in dorsal corticospinal tract (dCST) 8 weeks after SCI. Furthermore, we found that EFS inhibited the activation of calpain and caspase-3, as well as the expression of Bax, as detected by Western blot analysis. Moreover, EFS decreased cellular apoptosis, as measured by TUNEL, within 4 weeks post-injury. Results suggest that early EFS could significantly reduce spinal cord degeneration and improve functional and historical recovery. Furthermore, these neuroprotective effects may be related to

  9. Regulation of the intracellular free calcium concentration in single rat dorsal root ganglion neurones in vitro.

    PubMed Central

    Thayer, S A; Miller, R J

    1990-01-01

    1. Simultaneous whole-cell patch-clamp and Fura-2 microfluorimetric recordings of calcium currents (ICa) and the intracellular free Ca2+ concentration ([Ca2+]i) were made from neurones grown in primary culture from the dorsal root ganglion of the rat. 2. Cells held at -80 mV and depolarized to 0 mV elicited a ICa that resulted in an [Ca2+]i transient which was not significantly buffered during the voltage step and lasted long after the cell had repolarized and the current ceased. The process by which the cell buffered [Ca2+]i back to basal levels could best be described with a single-exponential equation. 3. The membrane potential versus ICa and [Ca2+]i relationship revealed that the peak of the [Ca2+]i transient evoked at a given test potential closely paralleled the magnitude of the ICa suggesting that neither voltage-dependent nor Ca2(+)-induced Ca2+ release from intracellular stores made a significant contribution to the [Ca2+]i transient. 4. When the cell was challenged with Ca2+ loads of different magnitude by varying the duration or potential of the test pulse, [Ca2+]i buffering was more effective for larger Ca2+ loads. The relationship between the integrated ICa and the peak of the [Ca2+]i transient reached an asymptote at large Ca2+ loads indicating that Ca2(+)-dependent processes became more efficient or that low-affinity processes had been recruited. 5. Inhibition of Ca2+ influx with neuropeptide Y demonstrated that inhibition of a large ICa produced minor alterations in the peak of the [Ca2+]i transient, while inhibition of smaller currents produced corresponding decreases in the [Ca2+]i transient. Thus, inhibition of the ICa was reflected by a change in the peak [Ca2+]i only when submaximal Ca2+ loads were applied to the cell, implying that modulation of [Ca2+]i is dependent on the activation state of the cells. 6. Intracellular dialysis with the mitochondrial Ca2+ uptake blocker Ruthenium Red in whole-cell patch-clamp experiments removed the buffering

  10. High-resolution MRI of intact and transected rat spinal cord.

    PubMed

    Fraidakis, M; Klason, T; Cheng, H; Olson, L; Spenger, C

    1998-10-01

    Spinal cord transection at midthoracic level leads to an immediate loss of hindlimb motor function as well as to a progressive degeneration of descending and ascending spinal cord pathways. Thoracic spinal cord in unlesioned control rats and in rats 2 to 6 months after complete midthoracic transection were imaged in vivo using an ultrahigh-field (4.7 T) magnetic resonance spectrometer. High-resolution spin-echo and inversion-recovery pulse sequences were employed. In addition, the apparent diffusion coefficients (ADCs) in longitudinal and transverse directions of the spinal cord were determined. Anatomical MRI findings were confirmed in histological spinal cord tissue preparations. In healthy spinal cord, gray and white matter were easily discerned in proton density-weighted images. An infield resolution of max. 76 micrometers per pixel was achieved. In animals with chronic spinal cord transection changes in gray-white matter structure and contrast were observed toward the cut end. The spinal cord stumps showed a tapering off. This coincided with changes in the longitudinal/transverse ADC ratio. Fluid-filled cysts were found in most cases at the distal end of the rostral stump. The gap between the stumps contained richly vascularized scar tissue. Additional pathologic changes included intramedullary microcysts, vertebral dislocations, and in one animal compression of the spinal cord. In conclusion, MRI was found to be a useful method for in vivo investigation of anatomical and physiological changes following spinal cord transection and to estimate the degree of neural degeneration. In addition, MRI allows the description of the accurate extension of fluid spaces (e.g., cysts) and of water diffusion characteristics which cannot be achieved by other means in vivo.

  11. [Fast visualization of fat infiltration in dorsal muscles of the trunk at lumbar spinal column by magnetic resonance images (MR)].

    PubMed

    Pérez-Miguelsanz, María Juliana; Herrera-Hervás, Luis; Franco-López, María de Los Ángeles

    2014-11-01

    In magnetic resonance, fat is considered an "unwanted artifact or signal" which is suppressed when performing a clinical study, unless otherwise specified. The increase in obesity and associated diseases has become necessary to study fat deposits both in adipose tissue and ectopic fat. In this paper, we analyze the information that is available from the CD which patients receive after undergoing magnetic resonance imaging of the abdomen along with the medical report, using a personal computer, focusing on the fat deposits in spinal muscles of healthy adult volunteers or analyzes nonspecific low back pain. The application of colored interfaces or windows on gray resonance images is very useful to display fat deposits, especially when the observer is not familiar with these images. It is a fast, easy and intuitive method of semiquantitative muscle visualization of the ectopic fat.

  12. [Double spinal cord compression by dorsal meningioma and Paget's disease of a vertebra. A propos of 2 cases treated surgically].

    PubMed

    Rousseaux, P; Lerais, J M; Scherpereel, B; Bernard, M H; Pluot, M

    1982-01-01

    A spinal cord compression due to intradural meningioma appeared in two patients with vertebral X-Rays lesions of foreknown Paget's disease. These lesions were located at the same level that the meningioma in the second case and three vertebra below the meningioma in the first case. In both cases, it took one year between the first clinical symptoms and the surgical decision. We truly think the Paget's disease and its X-Rays vertebral lesions to be responsible for the waist of time in myelography and surgical schedule. No other case of meningioma associated with Paget's disease has been found through literature. Because the treatment of Paget's disease paraplegia is now mostly medical, we thought important to report our experience in order to avoid other delays in this unusual diagnosis.

  13. Investigation of the protective effect of erythropoietin on spinal cord injury in rats.

    PubMed

    Hong, Zhenghua; Hong, Huaxing; Chen, Haixiao; Wang, Zhangfu; Hong, Dun

    2011-09-01

    Erythropoietin (EPO) is a promising therapeutic agent used in a variety of spinal cord injuries. Therefore, identifying the specific molecular pathway mediating the neuronal protective effect of EPO after spinal cord injury (SCI) is of great value to the patients concerned. Platelet-derived growth factor (PDGF)-B is an important factor in the recovery of neurological function. We explored changes in the expression of PDGF-B in spinal cord injury rats after receiving EPO treatment. We used a weight-drop contusion SCI model, and EPO treatment group rats received single doses of EPO (1,000 U/kg i.p.) immediately after the operation. Seven days after the operation, the results revealed a more rapid recovery as noted by the higher BBB scores, less disruption and more neuronal regeneration of the spinal cord in the EPO treatment group than that in the SCI group. PDGF-B expression also increased in the EPO treatment group compared to that in the SCI group (P<0.01). This study showed that PDGF-B plays a role in the neuronal protective effect of EPO on spinal cord injury in rats, which may help to explain the quick recovery after EPO treatment of spinal cord injury.

  14. Glycyrrhizin attenuates rat ischemic spinal cord injury by suppressing inflammatory cytokines and HMGB1

    PubMed Central

    Gong, Gu; Yuan, Li-bang; Hu, Ling; Wu, Wei; Yin, Liang; Hou, Jing-li; Liu, Ying-hai; Zhou, Le-shun

    2012-01-01

    Aim: To investigate the neuroprotective effect of glycyrrhizin (Gly) against the ischemic injury of rat spinal cord and the possible role of the nuclear protein high-mobility group box 1 (HMGB1) in the process. Methods: Male Sprague-Dawley rats were subjected to 45 min aortic occlusion to induce transient lumbar spinal cord ischemia. The motor functions of the animals were assessed according to the modified Tarlov scale. The animals were sacrificed 72 h after reperfusion and the lumbar spinal cord segment (L2–L4) was taken out for histopathological examination and Western blotting analysis. Serum inflammatory cytokine and HMGB1 levels were analyzed using ELISA. Results: Gly (6 mg/kg) administered intravenously 30 min before inducing the transient lumbar spinal cord ischemia significantly improved the hind-limb motor function scores, and reduced the number of apoptotic neurons, which was accompanied by reduced levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) in the plasma and injured spinal cord. Moreover, the serum HMGB1 level correlated well with the serum TNF-α, IL-1β and IL-6 levels during the time period of reperfusion. Conclusion: The results suggest that Gly can attenuate the transient spinal cord ischemic injury in rats via reducing inflammatory cytokines and inhibiting the release of HMGB1. PMID:22158106

  15. The effects of testosterone deficiency on the structural integrity of the penile dorsal nerve in the rat.

    PubMed

    Armagan, A; Hatsushi, K; Toselli, P

    2008-01-01

    Androgens play a vital role in erectile function and are known to have a neuroprotective role in the nervous system. This study investigated, in a rat model, the effects of testosterone deprivation and replacement on the morphology of the dorsal nerve of the rat penis at the light microscopy level. Two weeks after castration, male rats were infused with vehicle alone or 44 mug of testosterone for 2 weeks. Age-matched, sham-operated control animals were used for comparisons. Penile tissue samples were removed for histological analyses. The following parameters were assessed: (1) total myelin sheath thickness; (2) density of nerve fibers; and (3) axon cross-sectional area per nerve fiber. Castration resulted in a significant increase in axon cross-sectional area compared to that of the control and testosterone-treated animals (6.97+/-0.59 microm(2) per fiber in control animals to 14.32+/-0.44 microm(2) per fiber in castrated animals). Qualitatively, there were signs of nerve degeneration, particularly myelin sheath degeneration, in all sample groups. We did not observe statistically significant changes in myelin sheath thickness. There was a trend of reduced nerve density. Nerve degeneration was not quantified since this study was performed at the light microscopic level. This study suggests that testosterone has a neuroprotective role in the nerve fibers of the dorsal nerve and testosterone deficiency may lead to different forms of nerve degeneration resulting in anatomic alterations, thus contributing to erectile dysfunction.

  16. Silencing the α2 subunit of GABAA receptors in rat dorsal root ganglia reveals its major role in antinociception post-traumatic nerve injury

    PubMed Central

    Obradović, Aleksandar LJ; Scarpa, Joseph; Osuru, Hari P; Weaver, Janelle L; Park, Ji-Yong; Pathirathna, Sriyani; Peterkin, Alexander; Lim, Yunhee; Jagodic, Miljenko M; Todorovic, Slobodan M; Jevtovic-Todorovic, Vesna

    2015-01-01

    Background Neuropathic pain is likely the result of repetitive high frequency bursts of peripheral afferent activity leading to long-lasting changes in synaptic plasticity in the spinal dorsal horn (DH). Drugs that promote GABA activity in the DH provide partial relief of neuropathic symptoms. We examined how in vivo silencing of the GABAA α2 gene in DRG controls of NPP. Methods After crush injury to the right sciatic nerve of female rats, the α2 GABAA antisense and mismatch oligodeoxynucleotides or NO-711 (a GABA uptake inhibitor) were applied to the L5 DRG. In vivo behavioral assessment of nociception was conducted prior to the injury and ensuing 10 days (n=4–10). In vitro quantification of α2 GABAA protein and electrophysiology studies of GABAA currents were performed on acutely dissociated L5 DRG neurons at relevant time-points (n=6–14). Results NPP post-crush injury of a sciatic nerve in adult female rats coincides with significant down-regulation of the α2 subunit expression in the ipsilateral DRG (about 30%). Selective down-regulation of α2 expression in DRGs significantly worsens mechanical (2.55±0.75 to 5.16±1.16) and thermal (7.97±0.96 to 5.51±0.75) hypersensitivity in crush-injured animals and causes development of significant mechanical (2.33±0.40 to 5.00±0.33) and thermal (10.80±0.29 to 7.34±0.81) hypersensitivity in sham animals (data shown as MEAN±SD). Conversely, up-regulation of endogenous GABA via blockade of its uptake in DRG alleviates NPP. Conclusions The GABAA receptor in the DRG plays an important role in pathophysiology of NPP caused by sciatic nerve injury and represent promising target for novel pain therapies. PMID:26164299

  17. Gonadotropin-releasing hormone receptor in spinal cord neurons of embryos and adult rats.

    PubMed

    Quintanar, J Luis; Salinas, Eva; González, Rodolfo

    2009-09-11

    Mammalian gonadotropin-releasing hormone (GnRH) and its receptor have been found in the neuroendocrine reproductive axis. However, they can be localized in other extra-pituitary tissues as well including the central nervous system. The present study reports the expression of GnRH receptor and its mRNA in spinal cord neurons of rat embryos and adult rats, using immunohistochemistry and reverse transcriptase polymerase chain reaction (RT-PCR). Immunohistochemistry showed that the spinal cord neurons of rat embryos and adult rats expressed the GnRH receptor. The study of GnRH receptor mRNAs revealed that both cultured spinal cord neurons of rat embryos and adult rats expressed the GnRH receptor mRNA. Additional in vitro experiments showed that the expression of GnRH receptor mRNA was less in the spinal cord neurons exposed to GnRH compared to unexposed ones. These results raise the possibility that GnRH may play other roles independently from its participation in reproductive function.

  18. 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

  19. Reduced voluntary drive during sustained but not during brief maximal voluntary contractions in the first dorsal interosseous weakened by spinal cord injury.

    PubMed

    Prak, Roeland F; Doestzada, Marwah; Thomas, Christine K; Tepper, Marga; Zijdewind, Inge

    2015-12-01

    In able-bodied (AB) individuals, voluntary muscle activation progressively declines during sustained contractions. However, few data are available on voluntary muscle activation during sustained contractions in muscles weakened by spinal cord injury (SCI), where greater force declines may limit task performance. SCI-related impairment of muscle activation complicates interpretation of the interpolated twitch technique commonly used to assess muscle activation. We attempted to estimate and correct for the SCI-related-superimposed twitch. Seventeen participants, both AB and with SCI (American Spinal Injury Association Impairment Scale C/D) produced brief and sustained (2-min) maximal voluntary contractions (MVCs) with the first dorsal interosseous. Force and electromyography were recorded together with superimposed (doublet) twitches. MVCs of participants with SCI were weaker than those of AB participants (20.3 N, SD 7.1 vs. 37.9 N, SD 9.5; P < 0.001); MVC-superimposed twitches were larger in participants with SCI (SCI median 10.1%, range 2.0-63.2%; AB median 4.7%, range 0.0-18.4% rest twitch; P = 0.007). No difference was found after correction for the SCI-related-superimposed twitch (median 6.7%, 0.0-17.5% rest twitch, P = 0.402). Thus during brief contractions, the maximal corticofugal output that participants with SCI could exert was similar to that of AB participants. During the sustained contraction, force decline (SCI, 58.0%, SD 15.1; AB, 57.2% SD 13.3) was similar (P = 0.887) because participants with SCI developed less peripheral (P = 0.048) but more central fatigue than AB participants. The largest change occurred at