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Sample records for rat spinal dorsal

  1. Dorsal spinal venous occlusion in the rat.

    PubMed

    Martinez-Arizala, A; Mora, R J; Madsen, P W; Green, B A; Hayashi, N

    1995-04-01

    Occlusion of the major components of the spinal venous system is usually associated with spinal arteriovenous malformations or systemic thrombophlebitis. Although spinal venous system dysfunction has been implicated in compressive cord syndromes, myelopathies from decompression sickness, and spinal cord trauma, its pathophysiology remains unclear. To characterize disorders associated with spinal venous occlusion, we developed a model in the rat produced by focally coagulating the dorsal spinal vein transdurally at the T7 and T10 vertebral levels. Following such occlusion, venous stasis, sludging and perivascular hemorrhages in the small venous branches were observed. By 1 week postocclusion, animals developed hindlimb paralysis from which they partially recovered over time. Histologic examination in the acute phase disclosed tissue necrosis, edema, and hemorrhages predominantly in the dorsal aspect of the spinal cord. This was gradually replaced by an intense macrophagic infiltration and the partial formation of a cystic cavity by 1 month. These findings indicate that dorsal spinal vein occlusion in the rat causes significant neurologic and pathologic alterations. We conclude that this procedure produces a relevant animal model for the study of the pathophysiology of spinal venous occlusion, and it allows the characterization of its effects on spinal cord blood flow, the blood-spinal cord barrier, and the development of edema independent of cord compression. Our findings in this model provide an insight into one of the mechanisms of injury extension in spinal cord trauma and other disorders associated with spinal venous dysfunction.

  2. Spinal cord stimulation-induced analgesia: electrical stimulation of dorsal column and dorsal roots attenuates dorsal horn neuronal excitability in neuropathic rats.

    PubMed

    Guan, Yun; Wacnik, Paul W; Yang, Fei; Carteret, Alene F; Chung, Chih-Yang; Meyer, Richard A; Raja, Srinivasa N

    2010-12-01

    The sites of action and cellular mechanisms by which spinal cord stimulation reduces neuropathic pain remain unclear. We examined the effect of bipolar electrical-conditioning stimulation (50 Hz, 0.2 ms, 5 min) of the dorsal column and lumbar dorsal roots on the response properties of spinal wide dynamic range (WDR) neurons in rats after L5 spinal nerve injury. The conditioning stimulation intensity was set at the lowest current that evoked a peak antidromic sciatic Aα/β-compound action potential without inducing an Aδ- or C-compound action potential. Within 15 min of the dorsal column or root conditioning stimulation, the spontaneous activity rate of WDR neurons was significantly reduced in nerve-injured rats. Conditioning stimulation also significantly attenuated WDR neuronal responses to mechanical stimuli in nerve-injured rats and inhibited the C-component of the neuronal response to graded intracutaneous electrical stimuli applied to the receptive field in nerve-injured and sham-operated rats. It is noteworthy that dorsal column stimulation blocked windup of WDR neuronal response to repetitive intracutaneous electrical stimulation (0.5 Hz) in nerve-injured and sham-operated rats, whereas dorsal root stimulation inhibited windup only in sham-operated rats. Therefore, stimulation of putative spinal substrates at A-fiber intensities with parameters similar to those used by patients with spinal cord stimulators attenuated established WDR neuronal hyperexcitability in the neuropathic condition and counteracted activity-dependent increase in neuronal excitability (i.e., windup). These results suggest a potential cellular mechanism underlying spinal cord stimulation-induced pain relief. This in vivo model allows the neurophysiologic basis for spinal cord stimulation-induced analgesia to be studied.

  3. Nicotine facilitates glycine release in the rat spinal dorsal horn

    PubMed Central

    Kiyosawa, Atsuko; Katsurabayashi, Shutaro; Akaike, Norihiko; Pang, Zhi Ping; Akaike, Norio

    2001-01-01

    Nicotinic effects on glycine release were investigated in slices of lumbar spinal cord using conventional whole-cell recordings. In most of the substantia gelatinosa (SG) neurons tested, nicotine increased the frequency of the glycinergic spontaneous miniature inhibitory postsynaptic currents (mIPSCs). In a smaller proportion, nicotine evoked not only this same presynaptic response but also a postsynaptic response.Nicotinic facilitation of glycinergic mIPSCs was investigated in mechanically dissociated SG neurons using nystatin-perforated patch recordings. Nicotine (3 × 10−6 to 10−5m) reversibly enhanced the frequency of glycinergic mIPSCs without altering their amplitudes, thus indicating that nicotine facilitates glycine release through a presynaptic mechanism.Choline, a selective α7 subunit of nicotinic acetylcholine receptor (nAChR) agonist, had no effect on the mIPSC frequency while anatoxin A, a broad-spectrum agonist of nAChR, facilitated the mIPSC frequency.α-Bungarotoxin, a selective α7 subunit antagonist, failed to block the nicotinic facilitatory action. Mecamylamine, a broad-spectrum nicotinic antagonist, reversibly inhibited nicotinic action. Dihydro-β-erythroidine, a selective antagonist of nAChRs containing α4-β2 subunits, completely blocked nicotinic action.Ca2+-free but not Cd2+-containing bath solutions blocked nicotinic actions.We therefore conclude that nicotine facilitates glycine release in the substantia gelatinosa of the spinal dorsal horn via specific nAChRs containing α4-β2 subunits. This action on a subset of presynaptic nAChRs may underlie nicotine's modulation of noxious signal transmission and provide a cellular mechanism for the analgesic function of nicotine. PMID:11579160

  4. Electroacupuncture reduces the evoked responses of the spinal dorsal horn neurons in ankle-sprained rats.

    PubMed

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

    2011-05-01

    Acupuncture is shown to be effective in producing analgesia in ankle sprain pain in humans and animals. To examine the underlying mechanisms of the acupuncture-induced analgesia, the effects of electroacupuncture (EA) on weight-bearing forces (WBR) of the affected foot and dorsal horn neuron activities were examined in a rat model of ankle sprain. Ankle sprain was induced manually by overextending ligaments of the left ankle in the rat. Dorsal horn neuron responses to ankle movements or compression were recorded from the lumbar spinal cord using an in vivo extracellular single unit recording setup 1 day after ankle sprain. EA was applied to the SI-6 acupoint on the right forelimb (contralateral to the sprained ankle) by trains of electrical pulses (10 Hz, 1-ms pulse width, 2-mA intensity) for 30 min. After EA, WBR of the sprained foot significantly recovered and dorsal horn neuron activities were significantly suppressed in ankle-sprained rats. However, EA produced no effect in normal rats. The inhibitory effect of EA on hyperactivities of dorsal horn neurons of ankle-sprained rats was blocked by the α-adrenoceptor antagonist phentolamine (5 mg/kg ip) but not by the opioid receptor antagonist naltrexone (10 mg/kg ip). These data suggest that EA-induced analgesia in ankle sprain pain is mediated mainly by suppressing dorsal horn neuron activities through α-adrenergic descending inhibitory systems at the spinal level.

  5. Electroacupuncture reduces the evoked responses of the spinal dorsal horn neurons in ankle-sprained rats

    PubMed Central

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

    2011-01-01

    Acupuncture is shown to be effective in producing analgesia in ankle sprain pain in humans and animals. To examine the underlying mechanisms of the acupuncture-induced analgesia, the effects of electroacupuncture (EA) on weight-bearing forces (WBR) of the affected foot and dorsal horn neuron activities were examined in a rat model of ankle sprain. Ankle sprain was induced manually by overextending ligaments of the left ankle in the rat. Dorsal horn neuron responses to ankle movements or compression were recorded from the lumbar spinal cord using an in vivo extracellular single unit recording setup 1 day after ankle sprain. EA was applied to the SI-6 acupoint on the right forelimb (contralateral to the sprained ankle) by trains of electrical pulses (10 Hz, 1-ms pulse width, 2-mA intensity) for 30 min. After EA, WBR of the sprained foot significantly recovered and dorsal horn neuron activities were significantly suppressed in ankle-sprained rats. However, EA produced no effect in normal rats. The inhibitory effect of EA on hyperactivities of dorsal horn neurons of ankle-sprained rats was blocked by the α-adrenoceptor antagonist phentolamine (5 mg/kg ip) but not by the opioid receptor antagonist naltrexone (10 mg/kg ip). These data suggest that EA-induced analgesia in ankle sprain pain is mediated mainly by suppressing dorsal horn neuron activities through α-adrenergic descending inhibitory systems at the spinal level. PMID:21389301

  6. Segmental somatotopic organization of cutaneous afferent fibers in the lumbar spinal cord dorsal horn in rats.

    PubMed

    Takahashi, Yuzuru; Aoki, Yasuchika; Doya, Hideo

    2007-03-01

    In the present study, we investigated the central representation of segmental cutaneous afferent fiber projection fields in the horizontal plane of the spinal cord dorsal horn in adult rats. The neurotracer 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (Dil) was applied to spinal nerves T12-S2 and cutaneous ventrodorsal axial lines T13-S1. The Dil fluorescent zones in transverse sections of the dorsal horn were observed microscopically. Mediolateral locations of Dil fluorescent zones were measured, followed by reorganization on the horizontal plane through lamina I-I111. Rostral and caudal boundary lines of the central projection fields of spinal nerves T12-S2 formed 'waves' in the horizontal plane of the dorsal horn, pitching rostrocaudally about one spinal cord segment. The rostral and caudal apexes of the waves could be linked with those of adjacent segments, suggesting that the wave pattern is continuous rostrocaudally in the dorsal horn. The waves were markedly transformed in the central projection fields of the hindlimb and genital regions, in the L5 and L6 spinal cord segments.

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

    PubMed Central

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

    2011-01-01

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

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

    PubMed Central

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

    2013-01-01

    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 a ~70% loss of the sensory axons, by 24 hours. 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 hours. 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 hours. EB also caused an ~72% loss of microvessels. Lower concentrations of EB resulted in less axon, oligodendrocyte and microvessel loss, which were highly correlated (R2 = 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. PMID:23978615

  9. 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. © 2013.

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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

    2017-04-12

    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

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

    PubMed Central

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

    2015-01-01

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

  16. Extracellular glutamate in the dorsal horn of the lumbar spinal cord in the freely moving rat during hindlimb stepping.

    PubMed

    Walwyn, W M; Ta-Haung, J; Ackerson, L; Maidment, N T; Edgerton, V R

    1999-08-01

    The capacity to reestablish locomotor function after complete spinal cord transection in the adult mammal is now well documented. Further studies have shown different neurotransmitters to be involved in the initiation and maintenance of these locomotor patterns. However, there has been no in vivo evidence of the changes in glutamate or any other neurotransmitter in the extracellular space of the dorsal horn during an alternating motor pattern such as hindlimb stepping. This study describes an in vivo microdialysis technique to measure extracellular glutamate in the dorsal horn of the spinal cord in the fully awake intact rat. A concentric microdialysis probe was placed in the dorsal horn at L5, and 18 h later dialysate samples were collected at 20-min intervals before, during, and after 20 min of hindlimb stepping. During stepping, extracellular glutamate rose 150% above resting levels and returned to resting levels 40 min later. This increase may have occurred either as a result of primary afferent depolarization or modulation by the descending and ascending supraspinal pathways. In another series of experiments extracellular glutamate was, therefore, measured in the dorsal horn of the chronic spinally transected rat during 20 min of hindlimb stepping. Although the spinal group did not take as many steps as the intact group, those taking more than 40 steps showed a significant rise in extracellular glutamate, and the number of steps taken by the individual spinal rats correlated positively with the individual values of extracellular glutamate (r2 = 0.63). These results are consistent with glutamate being an important neurotransmitter in the spinal cord in normal locomotion.

  17. 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

  18. Postnatal maturation of endogenous opioid systems within the periaqueductal grey and spinal dorsal horn of the rat

    PubMed Central

    Kwok, Charlie H.T.; Devonshire, Ian M.; Bennett, Andrew J.; Hathway, Gareth J.

    2014-01-01

    Significant opioid-dependent changes occur during the fourth postnatal week in supraspinal sites (rostroventral medulla [RVM], periaqueductal grey [PAG]) that are involved in the descending control of spinal excitability via the dorsal horn (DH). Here we report developmentally regulated changes in the opioidergic signalling within the PAG and DH, which further increase our understanding of pain processing during early life. Microinjection of the μ-opioid receptor (MOR) agonist DAMGO (30 ng) into the PAG of Sprague-Dawley rats increased spinal excitability and lowered mechanical threshold to noxious stimuli in postnatal day (P)21 rats, but had inhibitory effects in adults and lacked efficacy in P10 pups. A tonic opioidergic tone within the PAG was revealed in adult rats by intra-PAG microinjection of CTOP (120 ng, MOR antagonist), which lowered mechanical thresholds and increased spinal reflex excitability. Spinal adminstration of DAMGO inhibited spinal excitability in all ages, yet the magnitude of this was greater in younger animals than in adults. The expression of MOR and related peptides were also investigated using TaqMan real-time polymerase chain reaction and immunohistochemistry. We found that pro-opiomelanocortin peaked at P21 in the ventral PAG, and MOR increased significantly in the DH as the animals aged. Enkephalin mRNA transcripts preceded the increase in enkephalin immunoreactive fibres in the superficial dorsal horn from P21 onwards. These results illustrate that profound differences in the endogenous opioidergic signalling system occur throughout postnatal development. PMID:24076162

  19. 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

  20. 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

  1. [Rebound depolarization of substantia gelatinosa neurons and its modulatory mechanisms in rat spinal dorsal horn].

    PubMed

    Li, Ling-Chao; Zhang, Da-Ying; Peng, Si-Cong; Wu, Jing; Jiang, Chang-Yu; Liu, Tao

    2016-02-20

    To investigate the rebound depolarization of substantia gelatinosa (SG) neurons in rat spinal dorsal horn and explore its modulatory mechanisms to provide better insights into rebound depolarization-related diseases. Parasagittal slices of the spinal cord were prepared from 3- to 5-week-old Sprague-Dawley rats. The electrophysiologic characteristics and responses to hyperpolarization stimulation were recorded using whole-cell patch-clamp technique. The effects of hyperpolarization-activated cyclic nucleotide gated cation (HCN) channel blockers and T-type calcium channel blockers on rebound depolarization of the neurons were studied. A total of 63 SG neurons were recorded. Among them, 23 neurons showed no rebound depolarization, 19 neurons showed rebound depolarization without spikes, and 21 neurons showed rebound depolarization with spikes. The action potential thresholds of the neurons without rebound depolarization were significantly higher than those of the neurons with rebound depolarization and spikes (-28.7∓1.6 mV vs -36.0∓2.0 mV, P<0.05). The two HCN channel blockers CsCl and ZD7288 significantly delayed the latency of rebound depolarization with spike from 45.9∓11.6 ms to 121.6∓51.3 ms (P<0.05) and from 36.2∓10.3 ms to 73.6∓13.6 ms (P<0.05), respectively. ZD7288 also significantly prolonged the latency of rebound depolarization without spike from 71.9∓35.1 ms to 267.0∓68.8 ms (P<0.05). The T-type calcium channel blockers NiCl2 and mibefradil strongly decreased the amplitude of rebound depolarization with spike from 19.9∓6.3 mV to 9.5∓4.5 mV (P<0.05) and from 26.1∓9.4 mV to 15.5∓5.0 mV (P<0.05), respectively. Mibefradil also significantly decreased the amplitude of rebound depolarization without spike from 14.3∓3.0 mV to 7.9∓2.0 mV (P<0.05). Nearly two-thirds of the SG neurons have rebound depolarizations modulated by HCN channel and T-type calcium channel.

  2. Decreased Substance P and NK1 Receptor Immunoreactivity and Function in the Spinal Cord Dorsal Horn of Morphine-Treated Neonatal Rats

    PubMed Central

    Thomson, Lisa M.; Terman, Gregory W.; Zeng, Jinsong; Lowe, Janet; Chavkin, Charles; Hermes, Sam M.; Hegarty, Deborah M.; Aicher, Sue A.

    2008-01-01

    Opiate analgesic tolerance is defined as a need for higher doses of opiates to maintain pain relief following prolonged opiate exposure. Though changes in the opioid receptor undoubtedly occur during conditions of opiate tolerance, there is increasing evidence that opiate analgesic tolerance is also caused by pronociceptive adaptations in the spinal cord. We have previously observed increased glutamate release in the spinal cord dorsal horn of neonatal rats made tolerant to the opiate morphine. Here we investigate whether spinal substance P (SP) and its receptor, the neurokinin 1 (NK1) receptor, are also modulated by prolonged morphine exposure. Immunocytochemical studies show decreased SP- and NK1-immunoreactivity in the dorsal horn of morphine-treated rats, whereas SP mRNA in the dorsal root ganglia is not changed. Electrophysiological studies show that SP fails to activate the NK1 receptor in the morphine-treated rat. Taken together, the data indicate that chronic morphine treatment in the neonatal rat is characterized by a loss of SP effects on the NK1 receptor in lamina I of the neonatal spinal cord dorsal horn. The results are discussed in terms of compensatory spinal cord processes that may contribute to opiate analgesic tolerance. Perspective This article describes anatomical and physiological changes that occur in the spinal cord dorsal horn of neonatal rats following chronic morphine treatment. These changes may represent an additional compensatory process of morphine tolerance and may represent an additional therapeutic target for the retention and restoration of pain relief with prolonged morphine treatment. PMID:17950674

  3. [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.

  4. 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

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

    PubMed

    Joukal, Marek; Klusáková, Ilona; Dubový, Petr

    2016-05-01

    The anatomical position of the subarachnoid space (SAS) in relation to dorsal root ganglia (DRG) and penetration of tracer from the SAS into DRG were investigated. We used intrathecal injection of methylene blue to visualize the anatomical position of the SAS in relation to DRG and immunostaining of dipeptidyl peptidase IV (DPP-IV) for detecting arachnoid limiting the SAS. Intrathecal administration of fluorescent-conjugated dextran (fluoro-emerald; FE) was used to demonstrate direct communication between the SAS and DRG. Intrathecal injection of methylene blue and DPP-IV immunostaining revealed that SAS delimited by the arachnoid was extended up to the capsule of DRG in a fold-like recess that may reach approximately half of the DRG length. The arachnoid was found in direct contact to the neuronal body-rich area in the angle between dorsal root and DRG as well as between spinal nerve roots at DRG. Particles of FE were found in the cells of DRG capsule, satellite glial cells, interstitial space, as well as in small and medium-sized neurons after intrathecal injection. Penetration of FE from the SAS into the DRG induced an immune reaction expressed by colocalization of FE and immunofluorescence indicating antigen-presenting cells (MHC-II+), activated (ED1+) and resident (ED2+) macrophages, and activation of satellite glial cells (GFAP+). Penetration of lumbar-injected FE into the cervical DRG was greater than that into the lumbar DRG after intrathecal injection of FE into the cisterna magna. Our results demonstrate direct communication between DRG and cerebrospinal fluid in the SAS that can create another pathway for possible propagation of inflammatory and signaling molecules from DRG primary affected by peripheral nerve injury into DRG of remote spinal segments. Copyright © 2016 Elsevier GmbH. All rights reserved.

  6. The effect of NR2B subunit palmitoylation at the spinal level after chronic dorsal root ganglia compression in rats.

    PubMed

    Xia, Tianjiao; Cui, Yin; Shi, Han; Ma, Zhengliang; Gu, Xiaoping

    2014-11-01

    The NR2B subunit (N-methyl-D-aspartate receptor 2B subunit) regulates the source of pain, and it participates in the formation of central sensitization. Palmitoylation was shown to be involved in the regulation of N-methyl-D-aspartate receptor internalization. In the present study, we investigated the effects of NR2B subunit palmitoylation in a chronic dorsal root ganglia compression (CCD) rat model. Paw mechanical withdrawal threshold and paw withdrawal thermal latency were used to assess mechanical allodynia and thermal hyperalgesia after a CCD operation and an intrathecal injection of the inhibitor of palmitoylation (2-bromopalmitate [2-BP]). The acyl-biotinyl exchange method, Western blotting, and coimmunoprecipitation were used to investigate the effects of pain processing and the expression of levels of NR2B palmitoylation and phosphorylation at the spinal level. CCD rats had long-lasting thermal hyperalgesia and mechanical allodynia, leading to upregulation of the level of NR2B palmitoylation and phosphorylation at the spinal level. An intrathecal treatment with 2-BP on day 14 after CCD surgery markedly improved pain behaviors and downregulated the expression of NR2B palmitoylation and phosphorylation. These data suggest that upregulated NR2B palmitoylation in CCD-induced neuropathic pain and intrathecal injection of 2-BP could reduce pain behaviors and NR2B phosphorylation. Our findings indicate that spinal NR2B palmitoylation is an important component of CCD-induced neuropathic pain, and it might be a potential target for chronic pain therapy.

  7. 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.

  8. Role of TRPM2 cation channels in dorsal root ganglion of rats after experimental spinal cord injury.

    PubMed

    Naziroğlu, Mustafa; Uğuz, Abdülhadi Cihangir; Ismailoğlu, Özgür; Çiğ, Bilal; Özgül, Cemil; Borcak, Muhammed

    2013-12-01

    We sought to determine the contribution of oxidative stress-dependent activation of TRPM2 and L-type voltage-gated Ca(2+) channels (VGCC) in dorsal root ganglion (DRG) neurons of rats after spinal cord injury (SCI). The rats were divided into 4 groups: control; sham control; SCI; and SCI+nimodipine groups. The neurons of the SCI groups were also incubated with non-specific TRPM2 channel blockers, 2-aminoethoxydiphenylborate (2-APB) and N-(p-amylcinnamoyl)anthranilic acid (ACA), before H2 O2 stimulation. The [Ca(2+) ]i concentrations were higher in the SCI group than in the control groups, although their concentrations were decreased by nimodipine and 2-APB. The H2 O2 -induced TRPM2 current densities in patch-clamp experiments were decreased by ACA and 2-APB incubation. In the nimodipine group, the TRPM2 channels of neurons were not activated by H2 O2 or cumene hydroperoxide. Increased Ca(2+) influx and currents in DRG neurons after spinal injury indicated TRPM2 and voltage-gated Ca(2+) channel activation. Copyright © 2013 Wiley Periodicals, Inc.

  9. Exercise alleviates hypoalgesia and increases the level of calcitonin gene-related peptide in the dorsal horn of the spinal cord of diabetic rats

    PubMed Central

    do Nascimento, Patrícia Severo; Lovatel, Gisele Agustini; Ilha, Jocemar; Xavier, Léder L; Schaan, Beatriz D'Agord; Achaval, Matilde

    2012-01-01

    OBJECTIVE: The aim of this study was to evaluate the effects of treadmill training on nociceptive sensitivity and immunoreactivity to calcitonin gene-related peptide in the dorsal horn of the spinal cord of diabetic rats. METHODS: Male Wistar rats were divided into three groups: control, diabetic and trained diabetic. Treadmill training was performed for 8 weeks. The blood glucose concentrations and body weight were evaluated 48 h after diabetes induction and every 30 days thereafter. The nociceptive sensitivity was evaluated using the tail-flick apparatus. The animals were then transcardially perfused, and the spinal cords were post-fixed, cryoprotected and sectioned in a cryostat. Immunohistochemistry for calcitonin gene-related peptide analysis was performed on the dorsal horn of the spinal cord. RESULTS: The nociceptive sensitivity analysis revealed that, compared with the control and trained diabetic animals, the latency to tail deflection on the apparatus was longer for the diabetic animals. Optical densitometry demonstrated decreased calcitonin gene-related peptide immunoreactivity in the dorsal horn of the spinal cord in diabetic animals, which was reversed by treadmill training. CONCLUSION: We concluded that treadmill training can alleviate nociceptive hypoalgesia and reverse decreased calcitonin gene-related peptide immunoreactivity in the dorsal horn of the spinal cord of diabetic animals without pharmacological treatment. PMID:23018308

  10. 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)

  11. Brain-derived neurotrophic factor expression in dorsal root ganglia of a lumbar spinal stenosis model in rats.

    PubMed

    Li, Qinliang; Liu, Yi; Chu, Zhaoming; Chen, Jinchuan; Dai, Fenglei; Zhu, Xiaorong; Hu, Ankang; Yun, Cai

    2013-12-01

    This study aimed to investigate the expression of brain-derived neurotrophic factor (BDNF) in dorsal root ganglia (DRG) of a rat model of lumbar spinal stenosis (LSS). Adult male rats were divided into the operation and sham operation groups. The operation group was comprised of the rat models of LSS. Walking distance and BDNF expression levels in DRG were measured in the two groups at different time points. The total BDNF protein levels and positive cell mean optical density (MOD) values in the operation group were significantly higher at each time point compared with that of the sham operation and preoperative control groups (P<0.05). The total BDNF protein levels and MOD values following sport in the operation group were significantly higher compared with those prior to sport (P<0.05). In the sham operation group, BDNF protein levels and MOD values before and after sport at each time point showed no significant differences than those of the operation group (P>0.05). Moreover, BDNF protein levels and MOD values in the operation group indicated a negative correlation with walking distance. The present study demonstrated that the expression of BDNF in rat models of LSS increased with time and was associated with a decrease in walking distance. BDNF was therefore important for the process of intermittent claudication caused by LSS.

  12. [Effect of electroacupuncture on phosphorylation of NR2B at Tyr 1742 site in the spinal dorsal horn of CFA rats].

    PubMed

    Liang, Yi; Fang, Jian-Qiao; Fang, Jun-Fan; Du, Jun-Ying; Qiu, Yu-Jie; Liu, Jin

    2013-10-01

    To observe the effect of electroacupuncture (EA) on phosphorylation of spinal NR2B at Tyr 1742 site in complete Freund's adjuvant (CFA) induced inflammatory pain rats. METHods Forty male Sprague Dawley rats were randomly divided into normal group (N group, n = 10), the model group (CFA group, n = 15), and the EA group (n = 15). The inflammatory pain model was established by subcutaneous injecting CFA (0.1 mL per rat) into the right hind paw. Paw withdrawal thresholds (PWTs) were measured before CFA injection (as the base), as well as at 24 h, 25 h, 3rd day, and 7th day after CFA injection. Phosphorylation of NR2B at Tyr 1742 site in the ispilateral spinal dorsal horn at the 3rd day post-injection were detected using immunohistochemical assay. PWTs in the CFA group were significantly lower than those of the N group at every detective time point post-injection (P < 0.01). PWTs were obviously lower in the EA group than in the N group at 24 h post-injection (P < 0.01). It showed increasing tendency, markedly higher than those of the CFA group at 25 h and 3rd day post-injection (P < 0.01). Compared with the N group, the ratio of p-NR2B positive cells in the ispilateral spinal dorsal horn of rats in the CFA group was up-regulated. Compared with the CFA group, the ratio of p-NR2B positive cells in the ispilateral spinal dorsal horn of rats showed a decreasing tendency in the EA group. EA might effectively inhibit CFA-induced inflammatory pain possibly associated with down-regulating phosphorylation of NR2B at Tyr 1742 site in the ispilateral spinal dorsal horn.

  13. 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.

  14. 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

  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. 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.

  17. 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.

  18. Dorsal spinal epidural cavernous hemangioma.

    PubMed

    Sanghvi, Darshana; Munshi, Mihir; Kulkarni, Bijal; Kumar, Abhaya

    2010-07-01

    A 61-year-old female patient presented with diffuse pain in the dorsal region of the back of 3 months duration. The magnetic resonance imaging showed an extramedullary, extradural space occupative lesion on the right side of the spinal canal from D5 to D7 vertebral levels. The mass was well marginated and there was no bone involvement. Compression of the adjacent thecal sac was observed, with displacement to the left side. Radiological differential diagnosis included nerve sheath tumor and meningioma. The patient underwent D6 hemilaminectomy under general anesthesia. Intraoperatively, the tumor was purely extradural in location with mild extension into the right foramina. No attachment to the nerves or dura was found. Total excision of the extradural compressing mass was possible as there were preserved planes all around. Histopathology revealed cavernous hemangioma. As illustrated in our case, purely epidural hemangiomas, although uncommon, ought to be considered in the differential diagnosis of spinal epidural soft tissue masses. Findings that may help to differentiate this lesion from the ubiquitous disk prolapse, more common meningiomas and nerve sheath tumors are its ovoid shape, uniform T2 hyperintense signal and lack of anatomic connection with the neighboring intervertebral disk or the exiting nerve root. Entirely extradural lesions with no bone involvement are rare and represent about 12% of all intraspinal hemangiomas.

  19. Dorsal spinal epidural cavernous hemangioma

    PubMed Central

    Sanghvi, Darshana; Munshi, Mihir; Kulkarni, Bijal; Kumar, Abhaya

    2010-01-01

    A 61-year-old female patient presented with diffuse pain in the dorsal region of the back of 3 months duration. The magnetic resonance imaging showed an extramedullary, extradural space occupative lesion on the right side of the spinal canal from D5 to D7 vertebral levels. The mass was well marginated and there was no bone involvement. Compression of the adjacent thecal sac was observed, with displacement to the left side. Radiological differential diagnosis included nerve sheath tumor and meningioma. The patient underwent D6 hemilaminectomy under general anesthesia. Intraoperatively, the tumor was purely extradural in location with mild extension into the right foramina. No attachment to the nerves or dura was found. Total excision of the extradural compressing mass was possible as there were preserved planes all around. Histopathology revealed cavernous hemangioma. As illustrated in our case, purely epidural hemangiomas, although uncommon, ought to be considered in the differential diagnosis of spinal epidural soft tissue masses. Findings that may help to differentiate this lesion from the ubiquitous disk prolapse, more common meningiomas and nerve sheath tumors are its ovoid shape, uniform T2 hyperintense signal and lack of anatomic connection with the neighboring intervertebral disk or the exiting nerve root. Entirely extradural lesions with no bone involvement are rare and represent about 12% of all intraspinal hemangiomas. PMID:21572634

  20. microRNA changes in the dorsal horn of the spinal cord of rats with chronic constriction injury: A TaqMan® Low Density Array study.

    PubMed

    Genda, Yuuki; Arai, Masae; Ishikawa, Masashi; Tanaka, Shunsuke; Okabe, Tadashi; Sakamoto, Atsuhiro

    2013-01-01

    Elucidation of the mechanisms underlying neuropathic pain is expected to aid in the discovery and selection of effective therapeutic methods. Currently, microRNA (miRNA) is thought to play an important role in the development and maintenance of the nervous system. We, therefore, hypothesized that miRNAs are involved in neuropathic pain, and investigated this possibility by analyzing miRNA expression in the dorsal horn of the spinal cord in a chronic constriction injury (CCI) rat model using the TaqMan® Low Density Array (TLDA). Neuropathic pain model rats were produced by CCI induced by ligation of the sciatic nerve. The miRNA expression in the dorsal horn of the spinal cord was analyzed in Day 0 rats, with no sciatic nerve ligation or sham operation, Day 7 rats, examined 7 days after sciatic nerve ligation or sham operation, and Day 14 rats, examined 14 days after sciatic nerve ligation or sham operation using TLDA. In this study, 111 miRNAs were significantly regulated in CCI rats in both the Day 7 and Day 14 groups compared with sham rats in both groups. Of these 111, there were 75 miRNAs (67.6%) that had been analyzed in previous reports and 36 miRNAs (32.4%) related to the development of tumors of the nervous system and neurodegenerative diseases. Certain miRNAs were reported to be related to neuropathic pain; miR-500, -221 and -21. The expression levels of a large number of miRNAs in the dorsal horn of the spinal cord in CCI rats changed. These results provide a step toward elucidation of the mechanisms underlying neuropathic pain.

  1. 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.

  2. A afferent fibers are involved in the pathology of central changes in the spinal dorsal horn associated with myofascial trigger spots in rats.

    PubMed

    Meng, Fei; Ge, Hong-You; Wang, Yong-Hui; Yue, Shou-Wei

    2015-11-01

    A afferent fibers have been reported to participate in the development of the central sensitization induced by inflammation and injuries. Current evidence suggests that myofascial trigger points (MTrPs) induce central sensitization in the related spinal dorsal horn, and clinical studies indicate that A fibers are associated with pain behavior. Because most of these clinical studies applied behavioral indexes, objective evidence is needed. Additionally, MTrP-related neurons in dorsal root ganglia and the spinal ventral horn have been reported to be smaller than normal, and these neurons were considered to be related to A fibers. To confirm the role of A fibers in MTrP-related central changes in the spinal dorsal horn, we studied central sensitization as well as the size of neurons associated with myofascial trigger spots (MTrSs, equivalent to MTrPs in humans) in the biceps femoris muscle of rats and provided some objective morphological evidence. Cholera toxin B subunit-conjugated horseradish peroxidase was applied to label the MTrS-related neurons, and tetrodotoxin was used to block A fibers specifically. The results showed that in the spinal dorsal horn associated with MTrS, the expression of glutamate receptor (mGluR1α/mGluR5/NMDAR1) increased, while the mean size of MTrS-related neurons was smaller than normal. After blocking A fibers, these changes reversed to some extent. Therefore, we concluded that A fibers participated in the development and maintenance of the central sensitization induced by MTrPs and were related to the mean size of neurons associated with MTrPs in the spinal dorsal horn.

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

    PubMed Central

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

    2008-01-01

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

  4. 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

  5. Quantitative Study of NPY-Expressing GABAergic Neurons and Axons in Rat Spinal Dorsal Horn*

    PubMed Central

    Polgár, Erika; Sardella, Thomas CP; Watanabe, Masahiko; Todd, Andrew J

    2011-01-01

    Between 25–40% of neurons in laminae I–III are GABAergic, and some of these express neuropeptide Y (NPY). We previously reported that NPY-immunoreactive axons form numerous synapses on lamina III projection neurons that possess the neurokinin 1 receptor (NK1r). The aims of this study were to determine the proportion of neurons and GABAergic boutons in this region that contain NPY, and to look for evidence that they selectively innervate different neuronal populations. We found that 4–6% of neurons in laminae I–III were NPY-immunoreactive and based on the proportions of neurons that are GABAergic, we estimate that NPY is expressed by 18% of inhibitory interneurons in laminae I–II and 9% of those in lamina III. GABAergic boutons were identified by the presence of the vesicular GABA transporter (VGAT) and NPY was found in 13–15% of VGAT-immunoreactive boutons in laminae I–II, and 5% of those in lamina III. For both the lamina III NK1r-immunoreactive projection neurons and protein kinase Cγ (PKCγ)-immunoreactive interneurons in lamina II, we found that around one-third of the VGAT boutons that contacted them were NPY-immunoreactive. However, based on differences in the sizes of these boutons and the strength of their NPY-immunoreactivity, we conclude that these originate from different populations of interneurons. Only 6% of VGAT boutons presynaptic to large lamina I projection neurons that lacked NK1rs contained NPY. These results show that NPY-containing neurons make up a considerable proportion of the inhibitory interneurons in laminae I–III, and that their axons preferentially target certain classes of dorsal horn neuron. J. Comp. Neurol. 519:1007–1023, 2011. © 2010 Wiley-Liss, Inc. PMID:21344400

  6. 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.

  7. BDNF induces late-phase LTP of C-fiber evoked field potentials in rat spinal dorsal horn.

    PubMed

    Zhou, Li-Jun; Zhong, Yi; Ren, Wen-Jie; Li, Yong-Yong; Zhang, Tong; Liu, Xian-Guo

    2008-08-01

    Several lines of evidence have shown that in some brain regions brain-derived neurotrophic factor (BDNF) is important for long-term potentiation (LTP), a synaptic model of memory storage. In the present work we evaluate the role of BDNF in LTP of C-fiber evoked field potentials in spinal dorsal horn, a synaptic model of pain memory. We found that spinal application of BDNF-induced LTP of C-fiber evoked field potentials with a long latency, lasting for >8 h, and the effect was blocked by either tyrosine kinase inhibitor (K252a) or BNDF scavenger (TrkB-Fc). The potentiation produced by BDNF was occluded by late-phase LTP (L-LTP) but not by early-phase LTP (E-LTP) induced by electrical stimulation. Pretreatment of K252a or TrkB-Fc selectively blocked spinal L-LTP induced by low-frequency stimulation (LFS) but not E-LTP. BDNF-induced LTP was completely abolished by the protein synthesis inhibitor (anisomycin), by N-methyl-D-aspartate (NMDA) receptor blocker (MK-801), by extracellular signal-regulated protein kinase (ERK) inhibitor (PD98059) or by p38 mitogen-activated protein kinase (MAPK) inhibitor (SB203580) but not by c-Jun N-terminal kinase (JNK) inhibitor (SP600125). Nuclear factor-kappaB (NF-kappaB) inhibitor (PDTC) also suppressed spinal BDNF-LTP. The results suggest that BDNF play a crucial role in protein synthesis-dependent L-LTP in spinal dorsal horn via activation of ERK, p38 MAPK and NF-kappaB signal pathways.

  8. 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.

  9. 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

  10. Effect of resveratrol on c-fos expression of rat trigeminal spinal nucleus caudalis and C1 dorsal horn neurons following mustard oil-induced acute inflammation.

    PubMed

    Matsumoto, Yasuhiro; Komatsu, Kyouhei; Shimazu, Yoshihito; Takehana, Shiori; Syouji, Yumiko; Kobayashi, Ayumu; Takeda, Mamoru

    2017-10-01

    The dietary constituent, resveratrol, was recently identified as a transient receptor potential ankyrin 1 (TRPA1) antagonist, voltage-dependent sodium ion (Na(+) ) channel, and cyclooxygenase-2 (COX-2) inhibitor. The aim of the present study was to investigate whether pretreatment with resveratrol attenuates acute inflammation-induced sensitization of nociceptive processing in rat spinal trigeminal nucleus caudalis (SpVc) and upper cervical (C1) dorsal horn neurons, via c-fos immunoreactivity. Mustard oil (MO), a TRPA1 channel agonist, was injected into the whisker pads of rats to induce inflammation. Pretreatment with resveratrol significantly decreased the mean thickness of inflammation-induced edema in whisker pads compared with those of untreated, inflamed rats. Ipsilateral of both the superficial and deep laminae of SpVc and C1 dorsal horn, there were significantly more c-fos-immunoreactive SpVc/C1 neurons in inflamed rats compared with naïve rats, and resveratrol pretreatment significantly decreased that number relative to untreated, inflamed rats. These results suggest that systemic administration of resveratrol attenuates acute inflammation-induced augmented nociceptive processing of trigeminal SpVc and C1 neurons. These findings support resveratrol as a potential therapeutic agent for use in alternative, complementary medicine to attenuate, or even prevent, acute trigeminal inflammatory pain. © 2017 Eur J Oral Sci.

  11. 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

  12. Electrical Stimulation Able to Trigger Locomotor Spinal Circuits Also Induces Dorsal Horn Activity.

    PubMed

    Dingu, Nejada; Deumens, Ronald; Taccola, Giuliano

    2016-01-01

    Investigate whether electrical stimulation of the spinal cord adapted to trigger locomotor patterns additionally influences dorsal horn networks. An in vitro model of isolated neonatal rat spinal cord was used to repetitively deliver electrical stimuli to lumbar dorsal roots and record from homolateral lumbar dorsal roots and ventral roots. Repetitive electrical lumbar dorsal root stimulation can affect both locomotor rhythms derived from ventral neuronal circuits and activity from dorsal neuronal circuits. These data suggest that neuro-electrostimulation protocols can simultaneously activate functionally distinct spinal neuronal circuits. © 2015 International Neuromodulation Society.

  13. 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.

  14. 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.

  15. Atorvastatin prevents neuroinflammation in chronic constriction injury rats through nuclear NFκB downregulation in the dorsal root ganglion and spinal cord.

    PubMed

    Chu, Li-Wen; Chen, Jun-Yih; Wu, Pao-Chu; Wu, Bin-Nan

    2015-06-17

    Atorvastatin, traditionally used to treat hyperlipidemia, belongs to a class of 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitors. This study investigated the antineuroinflammatory and antihyperalgesic effects of atorvastatin in dorsal root ganglia (DRG) and spinal cord for chronic constriction injury (CCI) neuropathic pain in rats. Fifty-four Sprague-Dawley rats were divided into three groups including sham, CCI, and CCI+atorvastatin. Rats were orally administered atorvastatin (10 mg/kg/day) once daily for 2 weeks after surgery and sacrificed at days 3, 7, and 14. All animals were assessed for mechanical allodynia and thermal hyperalgesia in both hindpaws. Western blotting, immunofluorescence, and enzyme-linked immunosorbent assay (ELISA) were used to detect inflammatory proteins and proinflammatory cytokines at day 7 after surgery. Pain behaviors were significantly reduced in the CCI+atorvastatin group compared to the CCI group. Atorvastatin attenuated CCI-induced inflammatory mediators (pAkt/Akt, COX-2, iNOS, EP1, and EP4) and reduced proinflammatory cytokines TNF-α and IL-1β levels in DRG and spinal cord. Atorvastatin also inhibited nuclear pNFκB activation. Double immunofluorescent staining further demonstrated that pNFκB proteins were decreased by atorvastatin in DRG satellite cells and spinal microglia. Atorvastatin may primarily inhibit the nuclear translocation of pNFκB to prevent CCI-induced peripheral neuropathic pain. Atorvastatin exhibits antineuroinflammatory and antinociceptive properties in the central and peripheral nerve systems.

  16. Comparison of intensity-dependent inhibition of spinal wide-dynamic range neurons by dorsal column and peripheral nerve stimulation in a rat model of neuropathic pain.

    PubMed

    Yang, F; Xu, Q; Cheong, Y-K; Shechter, R; Sdrulla, A; He, S-Q; Tiwari, V; Dong, X; Wacnik, P W; Meyer, R; Raja, S N; Guan, Y

    2014-08-01

    Spinal cord stimulation (SCS) and peripheral nerve stimulation (PNS) are thought to reduce pain by activating a sufficient number of large myelinated (Aβ) fibres, which in turn initiate spinal segmental mechanisms of analgesia. However, the volume of neuronal activity and how this activity is associated with different treatment targets is unclear under neuropathic pain conditions. We sought to delineate the intensity-dependent mechanisms of SCS and PNS analgesia by in vivo extracellular recordings from spinal wide-dynamic range neurons in nerve-injured rats. To mimic therapeutic SCS and PNS, we used bipolar needle electrodes and platinum hook electrodes to stimulate the dorsal column and the tibial nerve, respectively. Compound action potentials were recorded to calibrate the amplitude of conditioning stimulation required to activate A-fibres and thus titrate the volume of activation. Dorsal column stimulation (50 Hz, five intensities) inhibited the windup (a short form of neuronal sensitization) and the C-component response of wide-dynamic range neurons to graded intracutaneous electrical stimuli in an intensity-dependent manner. Tibial nerve stimulation (50 Hz, three intensities) also suppressed the windup in an intensity-dependent fashion but did not affect the acute C-component response. SCS and PNS may offer similar inhibition of short-term neuronal sensitization. However, only SCS attenuates spinal transmission of acute noxious inputs under neuropathic pain conditions. Our findings begin to differentiate peripheral from spinal-targeted neuromodulation therapies and may help to select the best stimulation target and optimum therapeutic intensity for pain treatment. © 2014 European Pain Federation - EFIC®

  17. 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

  18. 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.

  19. [Effects of electroacupuncture on glutamate and aspartic acid contents in the dorsal root ganglion and spinal cord in rats with neuropathic pain].

    PubMed

    Ma, Cheng; Li, Cui-xian; Yi, Jian-liang; Yan, Li-ping

    2008-08-01

    To observe the effect of electroacupuncture (EA) on pain threshold and contents of excitatory amino acids (EAA) in dorsal root ganglia (DRG) and spinal cord in rats with neuropathic pain. Fifty SD rats were randomly divided into control (C),model (M), sham-model (SM), EA, and sham-EA groups, with 10 cases in each. Neuropathic pain (spared nerve injury, SNI) model was established by cutting off the right common peroneal nerve and proso-tibial nerve (with the sural nerve reserved intact). Before and after surgery, the mechanical pain threshold (MPT) and thermal pain threshold (TPT) were measured respectively on the injured side under consciousness state. EA (2 Hz, 1-3 mA, adding 1 mA/10 min) was applied to "Huantiao" (GB 30) and "Weizhong" (BL 40) on the affected side for 30 min. For rats of sham-EA group, filiform needles were inserted into GB30 and BL40 simply without manipulation or electrical stimulation. The treatment was given once daily for 7 days. On the 15th day, the rats were sacrificed for sampling right L4-L6 DRG and spinal cord. The contents of neurotransmitters, glutamate (Glu) and aspartic acid (Asp) in DRG and spinal cord were detected with high performance liquid chromatography (HPLC). Micro-dialysis technique was used to collect the dialysate from the spinal cord, homogenated for measuring EAA by HPLC. In comparison with control group, after SNI, MPT decreased significantly from the 1st day on in model group. Compared with model group, on the 15th day, MPT increased significantly in both EA and sham-EA groups (P < 0.05, 0.01),but MPT of sham-EA was significantly lower than that of EA group (P < 0.05). No significant changes were found in TPT in 5 groups (P > 0.05). It suggested that sham EA still had an analgesic effect in spite of being lower than that of true EA. Compared with control group, the contents of Glu and Asp in the spinal cord tissue and micro-dialysate in model group increased significantly after SNI (P < 0.01). In comparison with

  20. 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

    Yan, Xisheng; Weng, Han-Rong

    2013-10-18

    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.

  1. 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

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

    PubMed

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

    2016-10-01

    Pregabalin is thought to exert its therapeutic effect in neuropathic pain via binding to α2δ-1 subunits of voltage-gated calcium (Ca(2+)) channels. However, the exact analgesic mechanism after its binding to α2δ-1 subunits remains largely unknown. Whether a clinical concentration of pregabalin (≈10μM) can cause acute inhibition of dorsal horn neurons in the spinal cord is controversial. To address this issue, we undertook intracellular Ca(2+)-imaging studies using spinal cord slices with an intact attached L5 dorsal root, and examined if pregabalin acutely inhibits the primary afferent stimulation-evoked excitation of dorsal horn neurons in normal rats and in rats with streptozotocin-induced painful diabetic neuropathy. Under normal conditions, stimulation of a dorsal root evoked Ca(2+) signals predominantly in the superficial dorsal horn. Clinically relevant (10μM) and a very high concentration of pregabalin (100μM) did not affect the intensity or spread of dorsal root stimulation-evoked Ca(2+) signals, whereas an extremely high dose of pregabalin (300μM) slightly but significantly attenuated Ca(2+) signals in normal rats and in diabetic neuropathic (DN) rats. There was no difference between normal rats and DN rats with regard to the extent of signal attenuation at all concentrations tested. These results suggest that the activity of dorsal horn neurons in the spinal cord is not inhibited acutely by clinical doses of pregabalin under normal or DN conditions. It is very unlikely that an acute inhibitory action in the dorsal horn is the main analgesic mechanism of pregabalin in neuropathic pain states. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. 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

  4. Curcumin exerts antinociceptive effects by inhibiting the activation of astrocytes in spinal dorsal horn and the intracellular extracellular signal-regulated kinase signaling pathway in rat model of chronic constriction injury.

    PubMed

    Ji, Feng-Tao; Liang, Jiang-Jun; Liu, Ling; Cao, Ming-Hui; Li, Feng

    2013-03-01

    Activation of glial cells and the extracellular signal-regulated kinase (ERK) signaling pathway play an important role in the development and maintenance of neuropathic pain. Curcumin can alleviate the symptom of inflammatory pain by inhibiting the production and release of interleukin and tumor necrosis factor. However, whether curcumin affects neuropathic pain induced by nerve injury and the possible mechanism involved are still unknown. This study investigated the effects of tolerable doses of curcumin on the activation of astrocytes and ERK signaling in the spinal dorsal horn in rat model of neuropathic pain. Adult male Sprague-Dawley rats were randomly divided into three groups: a control (sham operated) group, and chronic constriction injury groups (to induce neuropathic pain) that were either untreated or treated with curcumin. Thermal and mechanical hyperalgesia thresholds were measured. The distribution and morphological changes of astrocytes were observed by immunofluorescence. Western blotting was used to detect changes in the expression of glial fibrillary acid protein (GFAP) and phosphorylated ERK. Injured rats showed obvious mechanical allodynia and thermal hyperalgesia. The number of GFAP-positive astrocytes, and the fluorescence intensity of GFAP were significantly increased in the spinal dorsal horn of injured compared with control rats. The soma of astrocytes also appeared hypertrophied in injured animals. Expression of GFAP and phosphorylated ERK was also significantly increased in the spinal dorsal horn of injured compared with control rats. Curcumin reduced the injury-induced thermal and mechanical hyperalgesia, the increase in the fluorescence intensity of GFAP and the hypertrophy of astrocytic soma, activation of GFAP and phosphorylation of ERK in the spinal dorsal horn. Curcumin can markedly alleviate nerve injury-induced neuropathic pain in rats. The analgesic effect of curcumin may be attributed to its inhibition of astrocyte hypertrophy

  5. Cell-type-specific excitatory and inhibitory circuits involving primary afferents in the substantia gelatinosa of the rat spinal dorsal horn in vitro

    PubMed Central

    Yasaka, Toshiharu; Kato, Go; Furue, Hidemasa; Rashid, Md Harunor; Sonohata, Motoki; Tamae, Akihiro; Murata, Yuzo; Masuko, Sadahiko; Yoshimura, Megumu

    2007-01-01

    The substantia gelatinosa (SG) of the spinal dorsal horn shows significant morphological heterogeneity and receives primary afferent input predominantly from Aδ- and C-fibres. Despite numerous anatomical and physiological studies, correlation between morphology and functional connectivity, particularly in terms of inhibitory inputs, remains elusive. To compare excitatory and inhibitory synaptic inputs on individual SG neurones with morphology, we performed whole-cell recordings with Neurobiotin-filled-pipettes in horizontal slices from adult rat spinal cord with attached dorsal roots. Based on dendritic arborization patterns, four major cell types were confirmed: islet, central, radial and vertical cells. Dorsal root stimulation revealed that each class was associated with characteristic synaptic inputs. Islet and central cells had monosynaptic excitatory inputs exclusively from C-afferents. Islet cells received primary-afferent-evoked inhibitory inputs only from Aδ-fibres, while those of central cells were mediated by both Aδ- and C-fibres. In contrast, radial and vertical cells had monosynaptic excitatory inputs from both Aδ- and C-fibres and inhibitory inputs mediated by both fibre types. We further characterized the neurochemical nature of these inhibitory synaptic inputs. The majority of islet, central and vertical cells exhibited GABAergic inhibitory inputs, while almost all radial cells also possessed glycinergic inputs. The present study demonstrates that SG neurones have distinct patterns of excitatory and inhibitory inputs that are related to their morphology. The neurotransmitters responsible for inhibitory inputs to individual SG neurones are also characteristic for different morphological classes. These results make it possible to identify primary afferent circuits associated with particular types of SG neurone. PMID:17347278

  6. 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.

  7. 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

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

    PubMed

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

    2014-08-01

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

  9. 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.

  10. Material basis for inhibition of Dragon's Blood on evoked discharges of wide dynamic range neurons in spinal dorsal horn of rats.

    PubMed

    Guo, Min; Chen, Su; Liu, Xiangming

    2008-11-01

    In vivo experiments were designed to verify the analgesic effect of Dragon's Blood and the material basis for this effect. Extracellular microelectrode recordings were used to observe the effects of Dragon's Blood and various combinations of the three components (cochinchinenin A, cochinchinenin B, and loureirin B) extracted from Dragon's Blood on the discharge activities of wide dynamic range (WDR) neurons in spinal dorsal horn (SDH) of intact male Wistar rats evoked by electric stimulation at sciatic nerve. When the Hill's coefficients describing the dose-response relations of drugs were different, based on the concept of dose equivalence, the equations of additivity surfaces which can be applied to assess the interaction between three drugs were derived. Adopting the equations and Tallarida's isobole equations used to assess the interaction between two drugs with dissimilar dose-response relations, the effects produced by various combinations of the three components in modulating the evoked discharge activities of WDR neurons were evaluated. Results showed that Dragon's Blood and its three components could inhibit the evoked discharge frequencies of WDR neurons in a concentration-dependent way. The Hill's coefficients describing dose-response relations of three components were different. Only the combined effect of cochinchinenin A, cochinchinenin B and loureirin B was similar to that of Dragons Blood. Furthermore, the combined effect was synergistic. This investigation demonstrated that through the synergistic interaction of the three components Dragon's Blood could interfere with the transmission and processing of pain signals in spinal dorsal horn. All these further proved that the combination of cochinchinenin A, cochinchinenin B, and loureirin B was the material basis for the analgesic effect of Dragon's Blood.

  11. 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.

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

    PubMed

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

    2016-01-01

    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. 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. 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). 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.

  13. 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

  14. Dorsal horn neurons firing at high frequency, but not primary afferents, release opioid peptides that produce μ-opioid receptor internalization in the rat spinal cord

    PubMed Central

    Song, Bingbing; Marvizón, Juan Carlos G.

    2008-01-01

    To determine what neural pathways trigger opioid release in the dorsal horn, we stimulated the dorsal root, the dorsal horn or the dorsolateral funiculus (DLF) in spinal cord slices, while superfusing them with peptidase inhibitors to prevent opioid degradation. Internalization of μ-opioid receptors (MORs) and neurokinin 1 receptors (NK1Rs) was measured to assess opioid and neurokinin release, respectively. Dorsal root stimulation at low, high or mixed frequencies produced abundant NK1R internalization but no MOR internalization, indicating that primary afferents do not release opioids. Moreover, capsaicin and NMDA also failed to produce MOR internalization. In contrast, dorsal horn stimulation elicited MOR internalization that increased with the frequency, being negligible at <10 Hz and maximal at 500 Hz. The internalization was abolished by the MOR antagonist CTAP, in the presence of low Ca2+, and by the Na+ channel blocker lidocaine, confirming that it was caused by opioid release and neuronal firing. DLF stimulation in “oblique” slices (encompassing the DLF and the dorsal horn of T11-L4) produced MOR internalization, but only in areas near the stimulation site. Moreover, cutting oblique slices across the dorsal horn (but not across the DLF) eliminated MOR internalization in areas distal to the cut, indicating that it was produced by signals traveling in the dorsal horn and not via the DLF. These findings demonstrate that some dorsal horn neurons release opioids when they fire at high frequencies, perhaps by integrating signals from the rostral ventromedial medulla, primary afferents and other areas of the spinal cord. PMID:14534251

  15. 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

  16. 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.

  17. 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

  18. 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

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

  5. 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.

  6. Contribution of adrenomedullin to the switch of G protein-coupled μ-opioid receptors from Gi to Gs in the spinal dorsal horn following chronic morphine exposure in rats.

    PubMed

    Wang, Dongmei; Zeng, Juan; Li, Qi; Huang, Jianzhong; Couture, Réjean; Hong, Yanguo

    2016-04-01

    Chronic exposure to morphine increases spinal adrenomedullin (AM) bioactivity resulting in the development and maintenance of morphine tolerance. This study investigated the possible involvement of AM in morphine-evoked alteration in μ-opioid receptor-coupled G proteins. Agents were administered intrathecally (i.t.) in rats. Nociceptive behaviours and cumulative dose-response of morphine analgesia were assessed. Neurochemicals in the spinal dorsal horn were assayed by immunoprecipitation, Western blot analysis and ELISA. Intrathecal injection of AM (8 μg) for 9 days decreased and increased the levels of μ receptor-coupled Gi and Gs proteins respectively. Morphine stimulation (5 μg) after chronic treatment with AM also induced an increase in cAMP production in the spinal dorsal horn. Co-administration of the selective AM receptor antagonist AM22-52 inhibited chronic morphine-evoked switch of G protein-coupled μ receptor from Gi to Gs. Chronic exposure to AM increased the phosphorylation of cAMP-responsive element-binding protein (CREB) and ERK. Co-administration of the PKA inhibitor H-89 (5 μg) or MEK1 inhibitor PD98059 (1 μg) reversed the AM-induced thermal/mechanical hypersensitivity, decline in morphine analgesic potency, switch of G protein-coupled μ receptor and increase in cAMP. The present study supports the hypothesis that an increase in AM activity in the spinal dorsal horn contributes to the switch of the μ receptor-coupled G protein from Gi to Gs protein via the activation of cAMP/PKA/CREB and ERK signalling pathways in chronic morphine use. © 2016 The British Pharmacological Society.

  7. Dorsal column mapping for intramedullary spinal cord tumor resection decreases dorsal column dysfunction.

    PubMed

    Mehta, Ankit Indravadan; Mohrhaus, Cindy A; Husain, Aatif M; Karikari, Isaac O; Hughes, Betsy; Hodges, Tiffany; Gottfried, Oren; Bagley, Carlos A

    2012-06-01

    Retrospective cohort study and technical report. To demonstrate, through our institutional series of intramedullary spinal tumor resection, the potential avoidance of dorsal column dysfunction after using dorsal column mapping. Surgical resection of intramedullary spinal cord tumors carries significant associated postoperative morbidity. Much of this morbidity is because of dorsal column dysfunction from the dorsal myelotomy. The inconsistency and distortion of anatomic landmarks for a midline myelotomy has posed a significant challenge for spine surgeons. Dorsal column mapping is a relative new technique that may decrease the morbidity associated with operative resection of intramedullary masses. A cohort of patients operated upon at our institution for intramedullary lesions were retrospectively reviewed. Neurologic examination changes were assessed through clinic notes and chart review. A total of 91 intramedullary tumors were assessed, with 80 patients without dorsal column mapping and 11 patients with dorsal column mapping. In our cohort of 91 patients with intramedullary tumors undergoing resection over the past decade, postoperative dorsal column dysfunction was observed in 45%. Dorsal column mapping decreased the frequency of new postoperative posterior column dysfunction. Patients with dorsal column mapping had a statistically significant decrease rate of new postoperative posterior column dysfunction of 9% compared with 50% for without mapping (P=0.01). Tumor histology was not found to correlate with worsening posterior column dysfunction in patients undergoing tumor resection. With our surgical cohort as an internal control, we found a decreased rate of postoperative posterior column dysfunction when using intraoperative dorsal column mapping. Our findings show the ability of this evolving technology to provide useful intraoperative information to localize the physiological midline and decrease the rate of posterior column dysfunction after

  8. Upregulation of adrenomedullin in the spinal cord and dorsal root ganglia in the early phase of CFA-induced inflammation in rats.

    PubMed

    Hong, Yanguo; Liu, Yushan; Chabot, Jean-Guy; Fournier, Alain; Quirion, Rémi

    2009-11-01

    Adrenomedullin (AM), a member of calcitonin gene-related peptide (CGRP) family, has been demonstrated to be a pronociceptive mediator [28]. This study was undertaken to investigate the role of AM in a model of complete Freund's adjuvant (CFA)-induced inflammatory pain. Injection of CFA, but not of saline, in the unilateral hindpaw produced an increase in the expression of AM-like immunoreactivity (AM-IR) in laminae I-II of the spinal cord as well as in small- and medium-sized dorsal root ganglion (DRG) neurons at 48 h. The content of AM in DRG on the side ipsilateral to CFA injection started to increase at 4 h and remained at high levels at 24 and 48 h. The selective antagonist of AM receptors, AM(22-52), administered intrathecally (i.t.) 24 h after CFA injection inhibited inflammation-associated hyperalgesia in a dose-dependent manner (2, 5 and 10 nmol). Impressively, this anti-hyperalgesic effect lasted for at least 24 h. I.t. administration of AM(22-52) (10 nmol) also reversed CFA-induced increase in AM-IR in the spinal dorsal horn and DRG. Furthermore, blockade of AM receptors abolished CFA-induced changes in the expression and content of CGRP-like immunoreactivity in these regions. Taken together, our results suggest that the upregulation of AM in DRG neurons contributes to the development of inflammatory pain, and this effect is mediated, at least in part, by enhancing the expression and release of CGRP. Blocking AM receptor downstream signaling effects using antagonists has the potential of relieving pain following the induction of inflammation.

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

    PubMed

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

    2014-09-18

    Neuropathic pain is a form of pathological nociception that occurs in a significant portion of traumatic spinal cord injury (SCI) patients, resulting in debilitating and often long-term physical and psychological burdens. While many peripheral and central mechanisms have been implicated in neuropathic pain, central sensitization of dorsal horn spinothalamic tract (STT) neurons is a major underlying substrate. Furthermore, dysregulation of extracellular glutamate homeostasis and chronic astrocyte activation play important underlying roles in persistent hyperexcitability of these superficial dorsal horn neurons. To date, central sensitization and astrocyte changes have not been characterized in cervical SCI-induced neuropathic pain models, despite the fact that a major portion of SCI patients suffer contusion trauma to cervical spinal cord. In this study, we have characterized 2 rat models of unilateral cervical contusion SCI that behaviorally result in chronic persistence of thermal hyperalgesia in the ipsilateral forepaw. In addition, we find that STT neurons are chronically activated in both models when compared to laminectomy-only uninjured rats. Finally, persistent astrocyte activation and significantly reduced expression of the major CNS glutamate transporter, GLT1, in superficial dorsal horn astrocytes are associated with both excitability changes in STT neurons and the neuropathic pain behavioral phenotype. In conclusion, we have characterized clinically-relevant rodent models of cervical contusion-induced neuropathic pain that result in chronic activation of both STT neurons and astrocytes, as well as compromise in astrocyte glutamate transporter expression. These models can be used as important tools to further study mechanisms underlying neuropathic pain post-SCI and to test potential therapeutic interventions. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. 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.

  13. “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

  14. Brain-derived neurotrophic factor is upregulated in the cervical dorsal root ganglia and spinal cord and contributes to the maintenance of pain from facet joint injury in the rat.

    PubMed

    Kras, Jeffrey V; Weisshaar, Christine L; Quindlen, Julia; Winkelstein, Beth A

    2013-10-01

    The facet joint is commonly associated with neck and low back pain and is susceptible to loading-induced injury. Although tensile loading of the cervical facet joint has been associated with inflammation and neuronal hyperexcitability, the mechanisms of joint loading-induced pain remain unknown. Altered brain-derived neurotrophic factor (BDNF) levels are associated with a host of painful conditions, but the role of BDNF in loading-induced joint pain remains undefined. Separate groups of rats underwent a painful cervical facet joint distraction or a sham procedure. Bilateral forepaw mechanical hypersensitivity was assessed and BDNF mRNA and protein levels were quantified in the dorsal root ganglion (DRG) and spinal cord at days 1 and 7. Facet joint distraction induced significant (P < 0.001) mechanical hypersensitivity at both time points. Painful joint distraction did not alter BDNF mRNA in the DRG compared with sham levels but did significantly increase (P < 0.016) BDNF protein expression over sham in the DRG at day 7. Painful distraction also significantly increased BDNF mRNA (P = 0.031) and protein expression (P = 0.047) over sham responses in the spinal cord at day 7. In a separate study, intrathecal administration of the BDNF-sequestering molecule trkB-Fc on day 5 after injury partially attenuated behavioral sensitivity after joint distraction and reduced pERK in the spinal cord at day 7 (P < 0.045). Changes in BDNF after painful facet joint injury and the effect of spinal BDNF sequestration in partially reducing pain suggest that BDNF signaling contributes to the maintenance of loading-induced facet pain but that additional cellular responses are also likely involved. Copyright © 2013 Wiley Periodicals, Inc.

  15. Dorsal cervical spinal arachnoid cyst (Type III) presenting with dorsal column dysfunction: A case report.

    PubMed

    Pillai, Mahesh Krishna

    2017-03-01

    Spinal arachnoid cysts are usually asymptomatic and discovered incidentally. Expansion of the cyst, whether acute, subacute or chronic, leads to neural compression resulting in radicuopathy and/or myelopathy. This case report is of a patient who presented primarily with posterior column dysfunction,subacute in onset and rapidly progressing. Images of the cervical spine showed a dorsal arachnoid cyst, causing significant cord compression and signal changes in the cord, with no scalloping of the vertebrae. The author explains the mechanism of rapid expansion of an asymptomatic spinal arachnoid cyst, causing neural compression leading to fast progression of neurological deficits. The dorsal location of the cyst, explain the absence of radiculopathy, which is a common presenting feature of ventrally located intradural arachnoid cyst.

  16. 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.

  17. Dorsal spinal epidural psammomatous meningioma in an adult male

    PubMed Central

    Pandey, Sharad; Singh, Kulwant; Sharma, Vivek; Ghosh, Amrita; Suman, Saurabh

    2016-01-01

    Meningiomas are benign in nature and arise from the arachnoid cells. They are mostly situated in the intracranial compartment, whereas spinal meningiomas are rare. Approximately, in 10% of cases, an extradural component is seen but an exclusively extradural meningioma is quite uncommon. However, WHO Grade II (atypical) and Grade III (anaplastic) tumors can behave aggressively. We reported a case of purely extradural psammomatous meningioma in an adult male affecting the dorsal spine although uncommon meningiomas should be included in the differential diagnosis of extradural intraspinal masses. PMID:26933358

  18. Dorsal spinal epidural psammomatous meningioma in an adult male.

    PubMed

    Pandey, Sharad; Singh, Kulwant; Sharma, Vivek; Ghosh, Amrita; Suman, Saurabh

    2016-01-01

    Meningiomas are benign in nature and arise from the arachnoid cells. They are mostly situated in the intracranial compartment, whereas spinal meningiomas are rare. Approximately, in 10% of cases, an extradural component is seen but an exclusively extradural meningioma is quite uncommon. However, WHO Grade II (atypical) and Grade III (anaplastic) tumors can behave aggressively. We reported a case of purely extradural psammomatous meningioma in an adult male affecting the dorsal spine although uncommon meningiomas should be included in the differential diagnosis of extradural intraspinal masses.

  19. 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.

  20. 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.

  1. 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. Published by Elsevier Ltd.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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

  7. Activation and circuitry of uterine-cervix-related neurons in the lumbosacral dorsal root ganglia and spinal cord at parturition.

    PubMed

    Puder, B A; Papka, R E

    2005-12-15

    Stimulation of the uterine cervix at parturition activates neural circuits involving primary sensory nerves and supraspinally projecting neurons of the lumbosacral spinal cord, resulting in output of hypothalamic neurohormones. Dorsal root ganglia (DRG) and spinal neurons of these circuits are not well-characterized. The objectives of this study were to detail the activation of DRG and spinal neurons of the L6/S1 levels that are stimulated at late pregnancy, verify hypothalamic projections of activated spinal neurons, and determine whether activated neurons express estrogen receptor-alpha (ERalpha). Expression of phosphorylated cyclic-AMP response element-binding protein (PCREB) and Fos immunohistochemistry were used to "mark" activated DRG and spinal neurons, respectively. Retrograde tracing identified uterine-cervix-related and spinohypothalamic neurons. Baseline PCREB expression in the DRG increased during pregnancy and peaked during the last trimester. Some PCREB-expressing neurons contained retrograde tracer identifying them as cervix-related neurons. Fos-expressing neurons were few in spinal cords of nonpregnant and day 22 pregnant rats but were numerous in parturient animals. Some Fos-expressing neurons located in the dorsal half of the spinal cord contained retrograde tracer identifying them as spinohypothalamic neurons. Some DRG neurons expressing PCREB also expressed ERalpha, and some spinal neurons activated at parturition projected axons to the hypothalamus and expressed ERalpha. These results indicate that DRG and spinal cord neurons are activated at parturition; that those in the spinal cord are present in areas involved in autonomic and sensory processing; that some spinal neurons project axons to the hypothalamus, ostensibly part of a neuroendocrine reflex; and that sensory and spinal neurons can respond to estrogens. Moreover, some activated sensory neurons may be involved in the animal's perception of labor pain.

  8. Proteomic analysis of the dorsal spinal cord in the mouse model of spared nerve injury-induced neuropathic pain.

    PubMed

    Park, Eun-Sung; Ahn, Jung-Mo; Jeon, Sang-Min; Cho, Hee-Jung; Chung, Ki-Myung; Cho, Je-Yoel; Youn, Dong-Ho

    2017-09-03

    Peripheral nerve injury often causes neuropathic pain and is associated with changes in the expression of numerous proteins in the dorsal horn of the spinal cord. To date, proteomic analysis method has been used to simultaneously analyze hundreds or thousands of proteins differentially expressed in the dorsal horn of the spinal cord in rats or dorsal root ganglion of rats with certain type of peripheral nerve injury. However, a proteomic study using a mouse model of neuropathic pain could be attempted because of abundant protein database and the availability of transgenic mice. In this study, whole proteins were extracted from the ipsilateral dorsal half of the 4(th)-6(th) lumbar spinal cord in a mouse model of spared nerve injury (SNI)-induced neuropathic pain. In-gel digests of the proteins size-separated on a polyacrylamide gel were subjected to reverse-phase liquid-chromatography coupled with electrospray ionization ion trap tandem mass spectrometry (MS/MS). After identifying proteins, the data were analyzed with subtractive proteomics using ProtAn, an in-house analytic program. Consequently, 15 downregulated and 35 upregulated proteins were identified in SNI mice. The identified proteins may contribute to the maintenance of neuropathic pain, and may provide new or valuable information in the discovery of new therapeutic targets for neuropathic pain.

  9. 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

  10. 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.

  11. 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.

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

    PubMed

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

    2015-10-01

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

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

    PubMed Central

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

    2015-01-01

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

  14. 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

  15. 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.

  16. 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.

  17. Channelrhodopsin-2-expressed dorsal root ganglion neurons activates calcium channel currents and increases action potential in spinal cord.

    PubMed

    Zhang, Yi; Yue, Jing; Ai, Midan; Ji, Zhigang; Liu, Zhiguo; Cao, Xuehong; Li, Li

    2014-07-01

    We used optogenetic techniques in spinal cord and dorsal root ganglion (DRG) neuron studies. This study investigated changes in channelrhodopsin-2 (ChR2) expression in the spinal cord and DRG neurons using optogenetic techniques. The results show the possibility of using optogenetics to treat neuropathic pain. Previous studies have shown that activated ChR2 induces an increase in DRG neuron action potential. Western blot analysis was used to measure ChR2 protein levels in the spinal cord and DRG neurons or rats intrathecally injected with ChR2 lentivirus. Electrophysiology recording was used to detect differences in action potential levels in the spinal cord and calcium channel currents in the DRG neurons. Our studies showed that ChR2 expression increased the action potential in the spinal cord and increased calcium channel currents in DRG neurons. We successfully expressed the ChR2 protein in the spinal cord and DRG neurons. We also found that ChR2 increased the action potential in the spinal cord and activated the calcium channel in DRG neurons. These findings support the research possibilities of using optogenetic studies to improve treatment for neuropathic pain. N/A.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-01-01

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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. [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.

  5. 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.

  6. Purification and culture of adult rat dorsal root ganglia neurons.

    PubMed

    Delree, P; Leprince, P; Schoenen, J; Moonen, G

    1989-06-01

    To study the trophic requirements of adult rat dorsal root ganglia neurons (DRG) in vitro, we developed a purification procedure that yields highly enriched neuronal cultures. Forty to fifty ganglia are dissected from the spinal column of an adult rat. After enzymatic and mechanical dissociation of the ganglia, myelin debris are eliminated by centrifugation on a Percoll gradient. The resulting cell suspension is layered onto a nylon mesh with a pore size of 10 microns. Most of the neurons, the diameter of which ranged from 17 microns to greater than 100 microns, are retained on the upper surface of the sieve; most of the non-neuronal cells with a caliber of less than 10 microns after trypsinization go through it. Recovery of neurons is achieved by reversing the mesh onto a Petri dish containing culture medium. Neurons to non-neurons ratio is 1 to 10 in the initial cell suspension and 1 to 1 after separation. When these purified neurons are seeded at a density of 3,000 neurons/cm2 in 6 mm polyornithine-laminin (PORN-LAM) coated wells, neuronal survival (assessed by the ability to extend neurites), measured after 48 hr of culture, is very low (from 0 to 16%). Addition of nerve growth factor (NGF) does not improve neuronal survival. However, when neurons are cultured in the presence of medium conditioned (CM) by astrocytes or Schwann cells, 60-80% of the seeded, dye-excluding neurons survive. So, purified adult DRG neurons require for their short-term survival and regeneration in culture, a trophic support that is present in conditioned medium from PNS or CNS glia.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Liver X Receptor α Is Involved in Counteracting Mechanical Allodynia by Inhibiting Neuroinflammation in the Spinal Dorsal Horn.

    PubMed

    Xu, Jing; Feng, Yi-Wei; Liu, Ling; Wang, Wei; Zhong, Xiong-Xiong; Wei, Xu-Hong; Liu, Xian-Guo

    2017-09-01

    Liver X receptors, including α and β isoforms, are ligand-activated transcription factors. Whether liver X receptor α plays a role in neuropathic pain is unknown. A spared nerve injury model was established in adult male rats and mice. Von Frey tests were performed to evaluate the neuropathic pain behavior; Western blot and immunohistochemistry were performed to understand the underlying mechanisms. Intrathecal injection of a specific liver X receptor agonist T0901317 or GW3965 could either prevent the development of mechanical allodynia or alleviate the established mechanical allodynia, both in rats and wild-type mice. GW3965 could inhibit the activation of glial cells and the expression of tumor necrosis factor-α (mean ± SD: 196 ± 48 vs. 119 ± 57; n = 6; P < 0.01) and interleukin 1β (mean ± SD: 215 ± 69 vs. 158 ± 74; n = 6; P < 0.01) and increase the expression of interleukin 10 in the spinal dorsal horn. All of the above effects of GW3965 could be abolished by liver X receptor α mutation. Moreover, more glial cells were activated, and more interleukin 1β was released in the spinal dorsal horn in liver X receptor α knockout mice than in wild-type mice after spared nerve injury. Aminoglutethimide, a neurosteroid synthesis inhibitor, blocked the inhibitory effect of T0901317 on mechanical allodynia, on the activation of glial cells, and on the expression of cytokines. Activation of liver X receptor α inhibits mechanical allodynia by inhibiting the activation of glial cells and rebalancing cytokines in the spinal dorsal horn via neurosteroids.

  8. 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.

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

    PubMed Central

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

    2016-01-01

    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. PMID:26655672

  10. 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.

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

    PubMed Central

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

    2010-01-01

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

  12. Utility of neurophysiological monitoring using dorsal column mapping in intramedullary spinal cord surgery.

    PubMed

    Yanni, Daniel S; Ulkatan, Sedat; Deletis, Vedran; Barrenechea, Ignacio J; Sen, Chandranath; Perin, Noel I

    2010-06-01

    Intramedullary spinal cord tumors can displace the surrounding neural tissue, causing enlargement and distortion of the normal cord anatomy. Resection requires a midline myelotomy to avoid injury to the posterior columns. Locating the midline for myelotomy is often difficult because of the distorted anatomy. Standard anatomical landmarks may be misleading in patients with intramedullary spinal cord tumors due to cord rotation, edema, neovascularization, or local scar formation. Misplacement of the myelotomy places the posterior columns at risk of significant postoperative disability. The authors describe a technique for mapping the dorsal column to accurately locate the midline. A group of 10 patients with cervical and thoracic intramedullary spinal cord lesions underwent dorsal column mapping in which a strip electrode was used to define the midline. After the laminectomy and durotomy, a custom-designed multielectrode grid was placed on the exposed dorsal surface of the spinal cord. The electrode is made up of 8 parallel Teflon-coated stainless-steel wires (76-microm diameter, spaced 1 mm apart) embedded in silastic with each of the wires stripped of its insulating coating along a length of 2 mm. This strip electrode maps the amplitude gradient of conducted spinal somatosensory evoked potentials elicited by bilateral tibial nerve stimulation. Using these recordings, the dorsal columns are topographically mapped as lying between two adjacent numbers. The authors conducted a retrospective analysis of the preoperative, immediate, and short-term postoperative neurological status, focusing especially on posterior column function. There were 8 women and 2 men whose mean age was 52 years. There were 4 ependymomas, 1 subependymoma, 1 gangliocytoma, 1 anaplastic astrocytoma, 1 cavernous malformation, and 2 symptomatic syringes requiring shunting. In all patients the authors attempted to identify the midline by using anatomical landmarks, and then proceeded with dorsal

  13. T-cell infiltration and signaling in the adult dorsal spinal cord is a major contributor to neuropathic pain-like hypersensitivity.

    PubMed

    Costigan, Michael; Moss, Andrew; Latremoliere, Alban; Johnston, Caroline; Verma-Gandhu, Monica; Herbert, Teri A; Barrett, Lee; Brenner, Gary J; Vardeh, Daniel; Woolf, Clifford J; Fitzgerald, Maria

    2009-11-18

    Partial peripheral nerve injury in adult rats results in neuropathic pain-like hypersensitivity, while that in neonatal rats does not, a phenomenon also observed in humans. We therefore compared gene expression profiles in the dorsal horn of adult and neonatal rats in response to the spared nerve injury (SNI) model of peripheral neuropathic pain. The 148 differentially regulated genes in adult, but not young, rat spinal cords indicate a greater microglial and T-cell response in adult than in young animals. T-cells show a large infiltration in the adult dorsal horn but not in the neonate after SNI. T-cell-deficient Rag1-null adult mice develop less neuropathic mechanical allodynia than controls, and central expression of cytokines involved in T-cell signaling exhibits large relative differences between young and adult animals after SNI. One such cytokine, interferon-gamma (IFNgamma), is upregulated in the dorsal horn after nerve injury in the adult but not neonate, and we show that IFNgamma signaling is required for full expression of adult neuropathic hypersensitivity. These data reveal that T-cell infiltration and activation in the dorsal horn of the spinal cord following peripheral nerve injury contribute to the evolution of neuropathic pain-like hypersensitivity. The neuroimmune interaction following peripheral nerve injury has therefore a substantial adaptive immune component, which is absent or suppressed in the young CNS.

  14. T-Cell Infiltration and Signaling in the Adult Dorsal Spinal Cord Is a Major Contributor to Neuropathic Pain-Like Hypersensitivity

    PubMed Central

    Costigan, Michael; Moss, Andrew; Latremoliere, Alban; Johnston, Caroline; Verma-Gandhu, Monica; Herbert, Teri A.; Barrett, Lee; Brenner, Gary J.; Vardeh, Daniel; Woolf, Clifford J.; Fitzgerald, Maria

    2010-01-01

    Partial peripheral nerve injury in adult rats results in neuropathic pain-like hypersensitivity, while that in neonatal rats does not, a phenomenon also observed in humans. We therefore compared gene expression profiles in the dorsal horn of adult and neonatal rats in response to the spared nerve injury (SNI) model of peripheral neuropathic pain. The 148 differentially regulated genes in adult, but not young, rat spinal cords indicate a greater microglial and T-cell response in adult than in young animals. T-cells show a large infiltration in the adult dorsal horn but not in the neonate after SNI. T-cell-deficient Rag1-null adult mice develop less neuropathic mechanical allodynia than controls, and central expression of cytokines involved in T-cell signaling exhibits large relative differences between young and adult animals after SNI. One such cytokine, interferon-γ (IFNγ), is upregulated in the dorsal horn after nerve injury in the adult but not neonate, and we show that IFNγ signaling is required for full expression of adult neuropathic hypersensitivity. These data reveal that T-cell infiltration and activation in the dorsal horn of the spinal cord following peripheral nerve injury contribute to the evolution of neuropathic pain-like hypersensitivity. The neuroimmune interaction following peripheral nerve injury has therefore a substantial adaptive immune component, which is absent or suppressed in the young CNS. PMID:19923276

  15. Spinal nociceptin inhibits AMPA-induced nociceptive behavior and Fos expression in rat spinal cord.

    PubMed

    Menéndez, Luis; Lastra, Ana; Villanueva, Noemí; Hidalgo, Agustín; Baamonde, Ana

    2003-02-01

    The effects of intrathecal nociceptin (NOCI) on the nociceptive behavior (biting, scratching and licking; BSL) and the spinal Fos expression induced by intrathecal administration of N-methyl-D-aspartate (NMDA, 4 microg/rat) or alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA, 2 microg/rat) were studied. Coadministration of NOCI (3 and 10 nmol/rat) with NMDA did not modify the NMDA-induced BSL or Fos expression. In contrast, NOCI (0.1-3 nmol/rat) dose-dependently inhibited the BSL behavior induced by AMPA. Furthermore, coadministration of NOCI (3 and 10 nmol/rat) significantly reduced the AMPA-induced expression of Fos protein in the superficial layers of the spinal dorsal horn. In order to test whether classical or opioid receptor-like type 1 (ORL1) receptors are involved in the inhibitions by NOCI of AMPA-evoked BSL, the corresponding antagonists were assayed. The administration of the nonselective opioid receptor antagonist, naloxone (10 mg/kg i.p.), did not modify the NOCI-induced inhibition of AMPA-evoked BSL. However, the selective ORL1 receptor antagonist, [N-Phe(1)]nociceptin-(1-13)-NH(2) (90 nmol/rat i.t.), completely prevented the NOCI-mediated inhibition of the nociceptive responses evoked by AMPA. In conclusion, NOCI, acting at ORL1 receptors can, at least in part, induce spinal analgesia by blocking the nociceptive responses produced through the stimulation of AMPA receptors.

  16. Nikolaus Friedreich and degenerative atrophy of the dorsal columns of the spinal cord

    PubMed Central

    Koeppen, Arnulf H.

    2013-01-01

    Nikolaus Friedreich (1825-1882) presented clinical findings in 6 patients with a severe hereditary disorder of the nervous system and secured full autopsies in 4 of them. He was fascinated by the spinal cord lesions in the siblings of two unrelated families, and in the first 3 of his 5 long articles stressed the destruction of the dorsal columns. He recognized the relatively minor symmetrical lesions of the anterolateral fasciculi but did not separate dorsal spinocerebellar tracts (Flechsig’s bundles) and corticospinal tracts. While he studied the dorsal spinal roots in great detail and established their principal abnormality, namely, axonal thinning without axonal loss, he reported dorsal root ganglia as entirely normal. He made an insightful description of atrophic neurons in the gracile nuclei (clavae) but overlooked the invariable atrophy of the dentate nuclei. He followed the families over a period of 14 years, but acknowledged the hereditary nature of the disease only very late. He proposed a developmental defect for the medulla oblongata, retaining his interpretation that the spinal lesion was inflammatory. This review honors Friedreich for his insight into a “new” disease in the late 19th century and updates his neuropathological findings. It is remarkable that Friedreich also described the abnormal hearts in the disease that now bears his name since hypertrophic cardiomyopathy is now recognized as the main cause of death in Friedreich’s ataxia. PMID:23859337

  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. 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

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. Calretinin-immunoreactive nerves in the uterus, pelvic autonomic ganglia, lumbosacral dorsal root ganglia and lumbosacral spinal cord.

    PubMed

    Papka, R E; Collins, J; Copelin, T; Wilson, K

    1999-10-01

    Nerves containing the calcium-binding protein calretinin have been reported in several organs but not in female reproductive organs and associated ganglia. This study was undertaken to determine if nerves associated with the uterus contain calretinin and the source(s) of calretinin-synthesizing nerves in the rat (are they sensory, efferent, or both?). Calretinin-immunoreactive nerves were present in the uterine horns and cervix where they were associated with arteries, uterine smooth muscle, glands, and the epithelium. Calretinin-immunoreactive terminals were apposed to neurons in the paracervical ganglia; in addition, some postganglionic neurons in this ganglion were calretinin positive. Calretinin perikarya were present in the lumbosacral dorsal root ganglia, no-dose ganglia, and lumbosacral spinal cord. Retrograde axonal tracing, utilizing Fluorogold injected into the uterus or paracervical parasympathetic ganglia, revealed calretinin-positive/Fluorogold-labeled neurons in the dorsal root and nodose ganglia. Also, capsaicin treatment substantially reduced the calretinin-positive fibers in the uterus and pelvic ganglia, thus indicating the sensory nature of these fibers. The presence of calretinin immunoreactivity identifies a subset of nerves that are involved in innervation of the pelvic viscera and have origins from lumbosacral dorsal root ganglia and vagal nodose ganglia. Though the exact function of calretinin in these nerves is not currently known, calretinin is likely to play a role in calcium regulation and their function.

  7. 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.

  8. 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.

  9. 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).

  10. [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.

  11. Release of immunoreactive somatostatin in the spinal dorsal horn of the cat.

    PubMed

    Morton, C R; Hutchison, W D; Hendry, I A

    1988-01-01

    Antibody microprobes were used to investigate the possible release of immunoreactive somatostatin (irSS) within the lumbar spinal cord of anaesthetized cats. A basal release of irSS was detected in the region of the substantia gelatinosa of the dorsal horn. By comparison with in vitro standards the concentration of SS detected in this region was estimated at 10(-7) M. This release of irSS was not significantly altered by electrical stimulation of large myelinated primary afferent fibres but was increased when unmyelinated afferents were additionally stimulated. Release of irSS was also detected at the spinal cord surface. The results support a role for somatostatin in nociceptive transmission in the spinal cord.

  12. 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.

  13. 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.

  14. 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.

  15. Spino-Olivary Projections in the Rat are Natomically Separate From Postsynaptic Dorsal Column Projections

    PubMed Central

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

    2013-01-01

    The gracile nucleus (GN) and lateral part of rostral dorsal accessory olive (rDAO) are important relays for indirect, postsynaptic dorsal column, and direct ascending pathways, respectively, that terminate as climbing fibers in the “hindlimb-receiving” parts of the C1 and C3 zones in the cerebellar cortex. While the spinal cells of origin of that project to GN and rDAO are from largely separate territories in the spinal cord, previous studies have indicated that there could be an area of overlap between these two populations in the medial dorsal horn. Given the access of these two ascending tracts to sensory (thalamic) versus sensorimotor (precerebellar) pathways, the present study therefore addresses the important question of whether or not individual neurons have the potential to contribute axons to both ascending pathways. A double-fluorescent tracer strategy was used in rats (red Retrobeads and Fluoro-Ruby or green Retrobeads and Fluoro-Emerald) to map the spatial distribution of cells of origin of the two projections in the lumbar spinal cord. The two pathways were found to receive input from almost entirely separate territories within the lumbar cord (levels L3–L5). GN predominantly receives input from lamina IV, while rDAO receives its input from three cell populations: medial laminae V–VI, lateral lamina V, and medial laminae VII–VIII. Cells that had axons that branched to supply both GN and rDAO represented only about 1% of either single-labeled cell population. Overall, the findings therefore suggest functional independence of the two ascending pathways. J. Comp. Neurol. 522:2179–2190, 2014. © 2013 Wiley Periodicals, Inc. PMID:24357064

  16. Frequency Mapping of Rat Spinal Cord at 7T

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  17. 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

  18. 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

  19. 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.

  20. 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

  1. Spinal autofluorescent flavoprotein imaging in a rat model of nerve injury-induced pain and the effect of spinal cord stimulation.

    PubMed

    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.

  2. Antinociception induced by PAG-microinjected dipyrone (metamizol) in rats: involvement of spinal endogenous opioids.

    PubMed

    Hernández, N; Vanegas, H

    2001-03-30

    Dipyrone microinjection into the periaqueductal gray matter (PAG) elicits antinociception in rats by activating endogenous opioidergic circuits in PAG and the rostral ventromedial medulla. We have now found that endogenous opioids in the spinal cord are also involved. Responses of dorsal spinal neurons to noxious stimulation of a hindpaw were diminished (to 38-44%) by dipyrone microinjection (100 microg/0.5 microl) into the PAG. This was abolished by application of naloxone (50 microg/50 microl) to the spinal cord. The fact that dipyrone, a non-opioid analgesic, activates opioidergic circuits may be clinically important.

  3. 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

  4. 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

  5. Convergent nociceptive input to spinal dorsal horn neurons after peripheral nerve injury.

    PubMed

    Terayama, Ryuji; Kishimoto, Noriko; Yamamoto, Yuya; Maruhama, Kotaro; Tsuchiya, Hiroki; Mizutani, Masahide; Iida, Seiji; Sugimoto, Tomosada

    2015-03-01

    The number of c-Fos protein-like immunoreactive (c-Fos-IR) neurons in the spinal dorsal horn evoked by noxious stimulation was previously shown to be increased following peripheral nerve injury, and this increase was proposed to reflect the neuropathic pain state. The aim of this study was to investigate whether anomalous convergent primary afferent input to spinal dorsal horn neurons contributed to nerve injury-induced c-Fos hyperinducibility. Double immunofluorescence labeling for c-Fos and phosphorylated extracellular signal-regulated kinase (p-ERK) was performed to detect convergent synaptic input from different branches of the sciatic nerve after injury to the tibial nerve. c-Fos expression and the phosphorylation of ERK were induced by noxious heat stimulation of the hindpaw and also by electrical stimulation (ES) of the injured tibial nerve, respectively. The number of c-Fos-IR neurons was significantly decreased 3 days after the injury. However, the number of c-Fos-IR neurons returned to the control level 14 days after the injury. P-ERK immunoreactive (p-ERK-IR) neurons were induced in the central terminal field of the tibial nerve by ES of the tibial nerve. The topographic distribution pattern and number of such p-ERK-IR neurons remained unchanged after the nerve injury. The time course of changes in the number of double-labeled neurons, that presumably received convergent primary afferent input, showed a pattern similar to that of c-Fos-IR neurons after the injury. These results indicate that convergent primary nociceptive input through neighboring intact nerves may contribute to c-Fos hyperinducibility in the spinal dorsal horn.

  6. 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

    2017-06-01

    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

  7. Recurrent dorsal root potentials and motoneuron morphology in the frog spinal cord.

    PubMed

    Shupliakov, O V; Antal, M; Székely, G

    1990-09-18

    About one third of motoneurons stimulated intracellularly evoked dorsal root potentials (DRP) in the lumbar segments of the isolated and perfused frog spinal cord. Axon collaterals were found in one of the 22 motoneurons filled with HRP (horseradish peroxidase) through the stimulating electrode. In further experiments injecting individual motoneurons with cobalt, and filling the ventral roots with HRP or cobalt, the frequency of occurrence of axon collaterals was about 2% of the number of labelled motor cells. It is suggested that the presence of motor axon collaterals is not indispensable in the generation of the DRP evoked by ventral root or motor cell stimulation.

  8. 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.

  9. 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

  10. 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.

  11. 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

  12. 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

  13. Risk factors for progressive neuromuscular scoliosis requiring posterior spinal fusion after selective dorsal rhizotomy.

    PubMed

    Ravindra, Vijay M; Christensen, Michael T; Onwuzulike, Kaine; Smith, John T; Halvorson, Kyle; Brockmeyer, Douglas L; Walker, Marion L; Bollo, Robert J

    2017-09-08

    OBJECTIVE Selective dorsal rhizotomy (SDR) via limited laminectomy is an effective treatment of lower-extremity spasticity in the pediatric population. Children with spasticity are also at risk for neuromuscular scoliosis; however, specific risk factors for progressive spinal deformity requiring posterior spinal fusion (PSF) after SDR are unknown. The authors' goal was to identify potential risk factors. METHODS The authors performed a retrospective cohort study of patients who underwent SDR via limited laminectomy between 2003 and 2014 and who had at least 1 year of follow-up. They analyzed demographic, clinical, and radiographic variables to elucidate risk factors for progressive neuromuscular scoliosis. The primary outcome was need for PSF. RESULTS One hundred thirty-four patients underwent SDR and had at least 12 months of follow-up (mean 65 months); 48 patients (36%) had detailed pre- and postoperative radiographic data available. The mean age at surgery was 10 years (SD 5.1 years). Eighty-four patients (63%) were ambulatory before SDR, 109 (82%) underwent a single-level laminectomy, and a mean of 53% of the dorsal rootlets from L-1 to S-1 were sectioned. Fifteen patients (11.2%) subsequently required PSF for progressive deformity. Nonambulatory status (p < 0.001) and a preoperative Cobb angle > 30° (p = 0.003) were significantly associated with PSF on univariate analysis, but no statistically significant correlation was found with any clinical or radiographic variable and PSF after SDR on multivariate regression analysis. CONCLUSIONS Patients with preoperative nonambulatory status and Cobb angle > 30° may be at risk for progressive spinal deformity requiring PSF after SDR. These are well-known risk factors for progressive deformity in children with spasticity in general. Although our analysis suggests SDR via limited laminectomy may not significantly accelerate the development of neuromuscular scoliosis, further case-control studies are critical to

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. Glutamine synthetase induced spinal seizures in rats.

    PubMed

    Shin, Dong Won; Yoon, Young Sul; Matsumoto, Masato; Huang, Wencheng; Ceraulo, Phil; Young, Wise

    2003-02-01

    Glutamine synthetase (GS) is a key enzyme in the regulation of glutamate neurotransmission in the central nervous system. It is responsible for converting glutamate to glutamine, consuming one ATP and NH3 in the process. Glutamate is neurotoxic when it accumulates in extracellular fluids. We investigated the effects of GS in both a spinal cord injury (SCI) model and normal rats. 0.1-ml of low (2- micro M) and high (55- micro M) concentrations of GS were applied, intrathecally, to the spinal cord of rats under pentobarbital anesthesia. Immediately after an intrathecal injection into the L1-L3 space, the rats developed convulsive movements. These movements initially consisted of myoclonic twitches of the paravertebral muscles close to the injection site, repeated tonic and clonic contractions and extensions of the hind limbs (hind limb seizures) that spread to the fore limbs, and finally rotational axial movements of the body. An EMG of the paravertebral muscles, fore and hind limbs, showed the extent of the muscle activities. GS (2- micro M) caused spinal seizures in the rats after the SCI, and GS (6- micro M) produced seizures in the uninjured anesthetized rats. Denatured GS (70 degrees C, 1 hour) also produced spinal seizures, although higher concentrations were required. We suggest that GS may be directly blocking the release of GABA, or the receptors, in the spinal cord.

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. LACK OF ANALGESIC EFFICACY OF SPINAL ONDANSETRON ON THERMAL AND MECHANICAL HYPERSENSITIVITY FOLLOWING SPINAL NERVE LIGATION IN THE RAT

    PubMed Central

    Peters, Christopher M.; Hayashida, Ken-ichiro; Ewan, Eric E.; Nakajima, Kunie; Obata, Hideaki; Xu, Qinghao; Yaksh, Tony L.; Eisenach, James C.

    2010-01-01

    The balance between descending inhibition and facilitation is thought to be disturbed in chronic pain states. Increased facilitation by spinally released serotonin has been suggested by demonstration that mechanically evoked neuronal responses of wide dynamic range neurons are inhibited by 5-HT3 receptor antagonists in rats following spinal nerve ligation (SNL) but not sham operation. Despite these physiologic data, the effects of spinal 5-HT3 receptor blockade on behavioral hypersensitivity and neurochemical alterations in spinal serotonergic system have not been thoroughly investigated following spinal nerve ligation in the rat. To test this, we acutely injected intrathecal ondansetron in rats between 14 and 30 days after SNL and assessed effects on thermal and mechanical hypersensitivity. We also determined the density of serotonergic nerve fibers, serotonin content and the levels of 5-HT3 receptors within the spinal cord at this time point. Intrathecal ondansetron (1, 3, 10, 30, and 100 μg) produced no effect on behavioral measures of thermal or mechanical hypersensitivity whereas intrathecal morphine (1μg) and gabapentin (200 μg) partially reversed thermal and mechanical hypersensitivity following SNL. In addition, SNL did not alter the density of serotonergic fibers or 5-HT3 receptor immunoreactivity or spinal tissue content of 5-HT within the dorsal horn. These results do not support anatomic plasticity of descending serotonergic pathways or tonic 5-HT3 receptor activity in maintaining hypersensitivity after nerve injury and in contrast to previous studies fail to demonstrate an anti-hypersensitivity effect of intrathecal injection of the 5-HT3 receptor antagonist ondansetron following peripheral nerve injury. Importantly, behavioral measures of mechanical hypersensitivity assess threshold responses whereas physiological studies of mechanically evoked neuronal responses involve application of suprathreshold stimuli. Thus, suprathreshold or more intense

  9. 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.

  10. 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

  11. Dorsal spinal cord stimulation obtunds the capacity of intrathoracic extracardiac neurons to transduce myocardial ischemia

    PubMed Central

    Ardell, Jeffrey L.; Cardinal, René; Vermeulen, Michel; Armour, J. Andrew

    2009-01-01

    Populations of intrathoracic extracardiac neurons transduce myocardial ischemia, thereby contributing to sympathetic control of regional cardiac indices during such pathology. Our objective was to determine whether electrical neuromodulation using spinal cord stimulation (SCS) modulates such local reflex control. In 10 anesthetized canines, middle cervical ganglion neurons were identified that transduce the ventricular milieu. Their capacity to transduce a global (rapid ventricular pacing) vs. regional (transient regional ischemia) ventricular stress was tested before and during SCS (50 Hz, 0.2 ms duration at 90% MT) applied to the dorsal aspect of the T1 to T4 spinal cord. Rapid ventricular pacing and transient myocardial ischemia both activated cardiac-related middle cervical ganglion neurons. SCS obtunded their capacity to reflexly respond to the regional ventricular ischemia, but not rapid ventricular pacing. In conclusion, spinal cord inputs to the intrathoracic extracardiac nervous system obtund the latter's capacity to transduce regional ventricular ischemia, but not global cardiac stress. Given the substantial body of literature indicating the adverse consequences of excessive adrenergic neuronal excitation on cardiac function, these data delineate the intrathoracic extracardiac nervous system as a potential target for neuromodulation therapy in minimizing such effects. PMID:19515981

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

    PubMed Central

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

    2014-01-01

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

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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

  18. Bilateral cervical contusion spinal cord injury in rats.

    PubMed

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

    2009-11-01

    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.

  19. 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

  20. 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.

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

    PubMed Central

    Gautam, Shree Hari; Verhagen, Justus V.

    2012-01-01

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

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

    PubMed

    Gautam, Shree Hari; Verhagen, Justus V

    2012-06-06

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

  3. 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.

  4. 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

  5. Effects of Combined Electrical Stimulation of the Dorsal Column and Dorsal Roots on Wide-Dynamic-Range Neuronal Activity in Nerve-Injured Rats.

    PubMed

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

    2015-10-01

    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. 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 min) or alternate (5 min) pattern inhibits WDR neuronal activity better than CS at DC alone (5 min). 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. 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 msec) 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. These findings suggest that combined stimulation of DC and DR may not be superior to DC stimulation alone for inhibition of WDR neurons. © 2015 International Neuromodulation Society.

  6. Electrical neuromodulation of the cervical spinal cord facilitates forelimb skilled function recovery in spinal cord injured rats.

    PubMed

    Alam, Monzurul; Garcia-Alias, Guillermo; Jin, Benita; Keyes, Jonathan; Zhong, Hui; Roy, Roland R; Gerasimenko, Yury; Lu, Daniel C; Edgerton, V Reggie

    2017-05-01

    Enabling motor control by epidural electrical stimulation of the spinal cord is a promising therapeutic technique for the recovery of motor function after a spinal cord injury (SCI). Although epidural electrical stimulation has resulted in improvement in hindlimb motor function, it is unknown whether it has any therapeutic benefit for improving forelimb fine motor function after a cervical SCI. We tested whether trains of pulses delivered at spinal cord segments C6 and C8 would facilitate the recovery of forelimb fine motor control after a cervical SCI in rats. Rats were trained to reach and grasp sugar pellets. Immediately after a dorsal funiculus crush at C4, the rats showed significant deficits in forelimb fine motor control. The rats were tested to reach and grasp with and without cervical epidural stimulation for 10weeks post-injury. To determine the best stimulation parameters to activate the cervical spinal networks involved in forelimb motor function, monopolar and bipolar currents were delivered at varying frequencies (20, 40, and 60Hz) concomitant with the reaching and grasping task. We found that cervical epidural stimulation increased reaching and grasping success rates compared to the no stimulation condition. Bipolar stimulation (C6- C8+ and C6+ C8-) produced the largest spinal motor-evoked potentials (sMEPs) and resulted in higher reaching and grasping success rates compared with monopolar stimulation (C6- Ref+ and C8- Ref+). Forelimb performance was similar when tested at stimulation frequencies of 20, 40, and 60Hz. We also found that the EMG activity in most forelimb muscles as well as the co-activation between flexor and extensor muscles increased post-injury. With epidural stimulation, however, this trend was reversed indicating that cervical epidural spinal cord stimulation has therapeutic potential for rehabilitation after a cervical SCI. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Plastic changes in lumbar segments after thoracic spinal cord injuries in adult rats: an integrative view of spinal nociceptive dysfunctions.

    PubMed

    Redondo-Castro, Elena; García-Alías, Guillermo; Navarro, Xavier

    2013-01-01

    Spinal cord injuries (SCI) cause motor, sensory and autonomic dysfunctions as well as neuropathic pain. We investigated plastic changes occurring in cord segments caudal to the lesion to assess their potential contribution to pain states after SCI. Different thoracic SCIs were performed in adult rats. Functional and algesimetry tests were performed along 3 months. Several elements of the spinal nociceptive circuitry were assessed by immunohistochemical analyses of lumbar segments. Injured animals manifested mechanical and thermal hyperalgesia. Wind-up responses and spinal reflexes were enhanced, indicating spinal hyperexcitability. We found an increase in density of nociceptive sensory afferences and in GABA inhibitory activity in dorsal horns, and increased glial reactivity. Serotoninergic descending fibers and contacts on ventral horn motoneurons were reduced. Motoneurons presented more abundant inhibitory inputs, identified by gephyrin. Not all the changes kept direct relationship to the severity of the injury. The existence of hyperalgesia despite the boost of inhibitory elements in the spinal cord confirms the dysbalance between excitatory and inhibitory mechanisms, leading to a general disinhibition. Widespread dysfunctions in remote segments after central injuries contribute to the appearance of pain, and they may be new targets for therapies aimed to modulate spinal dysfunctions after injury.

  8. 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

  9. Effects of peripheral nerve injury on parvalbumin expression in adult rat dorsal root ganglion neurons.

    PubMed

    Medici, Tom; Shortland, Peter J

    2015-12-16

    Parvalbumin (PV) is a calcium binding protein that identifies a subpopulation of proprioceptive dorsal root ganglion (DRG) neurons. Calcitonin gene-related peptide (CGRP) is also expressed in a high proportion of muscle afferents but its relationship to PV is unclear. Little is known of the phenotypic responses of muscle afferents to nerve injury. Sciatic nerve axotomy or L5 spinal nerve ligation and section (SNL) lesions were used to explore these issues in adult rats using immunocytochemistry. In naive animals, the mean PV expression was 25 % of L4 or L5 dorsal root ganglion (DRG) neurons, and this was unchanged 2 weeks after sciatic nerve axotomy. Colocalization studies with the injury marker activating transcription factor 3 (ATF3) showed that approximately 24 % of PV neurons expressed ATF3 after sciatic nerve axotomy suggesting that PV may show a phenotypic switch from injured to uninjured neurons. This possibility was further assessed using the spinal nerve ligation (SNL) injury model where injured and uninjured neurons are located in different DRGs. Two weeks after L5 SNL there was no change in total PV staining and essentially all L5 PV neurons expressed ATF3. Additionally, there was no increase in PV-ir in the adjacent uninjured L4 DRG cells. Co-labelling of DRG neurons revealed that less than 2 % of PV neurons normally expressed CGRP and no colocalization was seen after injury. These experiments clearly show that axotomy does not produce down regulation of PV protein in the DRG. Moreover, this lack of change is not due to a phenotypic switch in PV immunoreactive (ir) neurons, or de novo expression of PV-ir in uninjured neurons after nerve injury. These results further illustrate differences that occur when muscle afferents are injured as compared to cutaneous afferents.

  10. Low-intensity treadmill exercise promotes rat dorsal wound healing.

    PubMed

    Zhou, Wu; Liu, Guo-hui; Yang, Shu-hua; Mi, Bo-bin; Ye, Shu-nan

    2016-02-01

    In order to investigate the promoting effect of low-intensity treadmill exercise on rat dorsal wound healing and the mechanism, 20 Sprague-Dawley rats were randomly divided into two groups: exercise group (Ex) and non-exercise group (non-ex). The rats in Ex group were given treadmill exercise for one month, and those in non-ex group raised on the same conditions without treadmill exercise. Both groups received dorsal wound operation with free access to food and water. By two-week continuous observation and recording of the wound area, the healing rate was analyzed. The blood sample was collected at day 14 post-operation via cardiac puncture for determination of the number of endothelial progenitor cells (EPCs) by flow cytometry, and the concentrations of relevant cytokines such as basic fibroblast growth factor (bFGF), endothelial nitric oxide synthase (eNOS) and vascular endothelial growth factor (VEGF) were measured by ELISA. The skin tissue around the wound was dissected to observe the vascular density under the microscope after HE staining, to detect the mRNA level of VEGFR2 and angiopoietin-1 (Ang-1) receptor using RT-qPCR, and protein expression of a-smooth muscle actin (αSMA) and type III collagen (ColIII) using Western blotting. It was found that the wound area in Ex group was smaller at the same time point than in non-ex group. The number of circulating EPCs was greater and the concentrations of vasoactive factors such as VEGF, eNOS and bFGF were higher in Ex group than in non-ex group. HE staining displayed a higher vessel density in Ex group than in non-ex group. Moreover, the mRNA expression of VEGFR2 and Ang-1 detected in the wound tissue in Ex group was higher than in non-ex group. Meanwhile, the protein expression of αSMA and ColIII was more abundant in Ex group than in non-ex group. Conclusively, the above results demonstrate Ex rats had a higher wound healing rate, suggesting low-intensity treadmill exercise accelerates wound healing. The present

  11. Acetaminophen Metabolite N-Acylphenolamine Induces Analgesia via Transient Receptor Potential Vanilloid 1 Receptors Expressed on the Primary Afferent Terminals of C-fibers in the Spinal Dorsal Horn.

    PubMed

    Ohashi, Nobuko; Uta, Daisuke; Sasaki, Mika; Ohashi, Masayuki; Kamiya, Yoshinori; Kohno, Tatsuro

    2017-08-01

    The widely used analgesic acetaminophen is metabolized to N-acylphenolamine, which induces analgesia by acting directly on transient receptor potential vanilloid 1 or cannabinoid 1 receptors in the brain. Although these receptors are also abundant in the spinal cord, no previous studies have reported analgesic effects of acetaminophen or N-acylphenolamine mediated by the spinal cord dorsal horn. We hypothesized that clinical doses of acetaminophen induce analgesia via these spinal mechanisms. We assessed our hypothesis in a rat model using behavioral measures. We also used in vivo and in vitro whole cell patch-clamp recordings of dorsal horn neurons to assess excitatory synaptic transmission. Intravenous acetaminophen decreased peripheral pinch-induced excitatory responses in the dorsal horn (53.1 ± 20.7% of control; n = 10; P < 0.01), while direct application of acetaminophen to the dorsal horn did not reduce these responses. Direct application of N-acylphenolamine decreased the amplitudes of monosynaptic excitatory postsynaptic currents evoked by C-fiber stimulation (control, 462.5 ± 197.5 pA; N-acylphenolamine, 272.5 ± 134.5 pA; n = 10; P = 0.022) but not those evoked by stimulation of Aδ-fibers. These phenomena were mediated by transient receptor potential vanilloid 1 receptors, but not cannabinoid 1 receptors. The analgesic effects of acetaminophen and N-acylphenolamine were stronger in rats experiencing an inflammatory pain model compared to naïve rats. Our results suggest that the acetaminophen metabolite N-acylphenolamine induces analgesia directly via transient receptor potential vanilloid 1 receptors expressed on central terminals of C-fibers in the spinal dorsal horn and leads to conduction block, shunt currents, and desensitization of these fibers.

  12. Identification of Early RET+ Deep Dorsal Spinal Cord Interneurons in Gating Pain

    PubMed Central

    Cui, Lian; Miao, Xuerong; Liang, Lingli; Abdus-Saboor, Ishmail; Olson, William; Fleming, Michael S; Ma, Minghong; Tao, Yuan-Xiang; Luo, Wenqin

    2016-01-01

    The gate control theory (GCT) of pain proposes that pain- and touch-sensing neurons antagonize each other through spinal cord dorsal horn (DH) gating neurons. However, the exact neural circuits underlying the GCT remain largely elusive. Here, we identified a new population of deep layer DH (dDH) inhibitory interneurons that express the receptor tyrosine kinase Ret neonatally. These early RET+ dDH neurons receive excitatory as well as polysynaptic inhibitory inputs from touch- and/or pain-sensing afferents. In addition, they negatively regulate DH pain and touch pathways through both pre- and postsynaptic inhibition. Finally, specific ablation of early RET+ dDH neurons increases basal and chronic pain, whereas their acute activation reduces basal pain perception and relieves inflammatory and neuropathic pain. Taken together, our findings uncover a novel spinal circuit that mediates crosstalk between touch and pain pathways and suggest that some early RET+ dDH neurons could function as pain “gating” neurons. PMID:27545714

  13. 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

  14. Changes in the neuroglial cell populations of the rat spinal cord after local X-irradiation.

    PubMed

    Hubbard, B M; Hopewell, J W

    1979-10-01

    A 16 mm length of cervical spinal cord of young adult female rats was irradiated with 4000 rad of 250 kV X rays. Counts of astrocyte and oligodendrocyte nuclei were made in the dorsal columns of both irradiated and control cervical cords during the latent period before the onset of radionecrosis. The numbers of both astrocyte and oligodendrocyte nuclei were reduced one month after exposure to radiation. Both cell populations showed an apparent recovery but this was subsequently followed by a rapid loss of cells prior to the development of white-matter necrosis. The oligodendrocyte population in unirradiated spinal cords increased with age, and mitotic figures were observed among the neuroglia of both irradiated and control cervical spinal cords. A slow, natural turnover of neuroglial cells in the cervical spinal cord is proposed and the relevance of this to the manifestation of delayed white matter necrosis is discussed.

  15. 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. Copyright © 2014 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

  16. Histopathological and behavioral characterization of a novel cervical spinal cord displacement contusion injury in the rat.

    PubMed

    Pearse, D D; Lo, T P; Cho, K S; Lynch, M P; Garg, M S; Marcillo, A E; Sanchez, A R; Cruz, Y; Dietrich, W D

    2005-06-01

    Cervical contusive trauma accounts for the majority, of human spinal cord injury (SCI), yet experimental use of cervical contusion injury models has been limited. Considering that (1) the different ways of injuring the spinal cord (compression, contusion, and transection) induce very different processes of tissue damage and (2) the architecture of the spinal cord is not uniform, it is important to use a model that is more clinically applicable to human SCI. Therefore, in the current study we have developed a rat model of contusive, cervical SCI using the Electromagnetic Spinal Cord Injury Device (ESCID) developed at Ohio State University (OSU) to induce injury by spinal cord displacement. We used the device to perform mild, moderate and severe injuries (0.80, 0.95, and 1.1 mm displacements, respectively) with a single, brief displacement of <20 msec upon the exposed dorsal surface of the C5 cervical spinal cord of female (180-200 g) Fischer rats. Characterization of the model involved the analysis of the temporal histopathological progression of the injury over 9 weeks using histochemical stains to analyze white and gray mater integrity and immunohistochemistry to examine cellular changes and physiological responses within the injured spinal cord. Accompanying the histological analysis was a comprehensive determination of the behavioral functionality of the animals using a battery of motor tests. Characterization of this novel model is presented to enable and encourage its future use in the design and experimental testing of therapeutic strategies that may be used for human SCI.

  17. [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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

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

    PubMed Central

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

    2010-01-01

    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 (T3–T4) 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 T3–T4 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 T3–T4 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 T3 and T4 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 T3 and 8 (control), 37 (chemical) and 62 (mechanical) for T4. 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. PMID:20869348

  4. 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. Copyright © 2010 Elsevier B.V. All rights reserved.

  5. 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

  6. 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.

  7. Leukemia inhibitory factor induces sympathetic sprouting in intact dorsal root ganglia in the adult rat in vivo

    PubMed Central

    Thompson, Stephen W N; Majithia, Anooj A

    1998-01-01

    The role of the cytokine leukemia inhibitory factor (LIF) in axotomy-induced sprouting of postganglionic sympathetic fibres into the dorsal root ganglia was examined in the adult rat.Immunocytochemistry was used to study the distribution and density of tyrosine hydroxylase-immunoreactive (TH-IR) fibres within the lumbar dorsal root ganglia and lumbar spinal nerves 14 days following continuous intrathecal infusion of LIF (0.33 mg ml−1), or 14 days following unilateral peripheral nerve axotomy.In LIF-treated animals, numerous pericellular TH-IR basket-like structures were observed surrounding sensory neurones, which were absent from controls.The number of TH-IR fibres within the L3, L4 and L5 spinal nerves was significantly higher in LIF-treated animals than in control or saline-treated animals (P < 0.01, Student's t test).Unilateral ligation of the L4 spinal nerve or unilateral sciatic nerve ligation was also associated with the formation of TH-IR baskets around sensory neurones and a significant increase in the number of TH-IR fibres within the lumbar spinal nerves (P < 0.01, Student's t test).The percentage of neurones surrounded by TH-IR baskets within the L3 and L4 dorsal root ganglia following sciatic axotomy was significantly reduced in animals treated continuously for 2 weeks with a monoclonal antibody against the LIF receptor motif, gp130 (0.833 mg ml−1) (P < 0.05, Mann-Whitney U test). Antibody treatment did not reduce the axotomy-induced increase in TH-IR fibres within lumbar spinal nerves.These results demonstrate that exogenous application of the axotomy-associated cytokine LIF is associated with sprouting of uninjured postganglionic sympathetic neurones around sensory neurones within the dorsal root ganglion. It is likely that increased LIF expression following peripheral axotomy plays an important role in the novel sympathetic sprouting observed within sensory ganglia following peripheral nerve injury. PMID:9503339

  8. Estradiol modulates visceral hyperalgesia by increasing thoracolumbar spinal GluN2B subunit activity in female rats

    PubMed Central

    Ji, Yaping; Bai, Guang; Cao, Dong-Yuan; Traub, Richard J

    2015-01-01

    Background We previously reported estrogen modulates spinal NMDA receptor processing of colorectal pain through changes in spinal GluN1 subunit phosphorylation/expression. The purpose of the present study was to investigate whether spinal GluN2B containing NMDA receptors are involved in estrogen modulation of visceral pain processing. Methods Behavioral, molecular and immunocytochemical techniques were used to determine spinal GluN2B expression/phosphorylation and function 48 hrs following subcutaneous injection of estradiol (E2) or vehicle (safflower oil, Saff oil) in ovariectomized rats in the absence or presence of colonic inflammation induced by mustard oil. Key results E2 increased the magnitude of the visceromotor response (VMR) to colorectal distention compared to Saff oil in non-inflamed rats. Intrathecal injection of the GluN2B subunit antagonist, Ro 25-6981, had no effect on the VMR in non-inflamed E2 or Saff oil rats. Colonic inflammation induced visceral hyperalgesia in E2, but not Saff oil rats. Visceral hyperalgesia in E2 rats was blocked by intrathecal GluN2B subunit selective antagonists. In inflamed rats, E2 increased GluN2B protein and gene expression in the thoracolumbar (TL), but not lumbosacral (LS), dorsal spinal cord. Immunocytochemical labeling showed a significant increase of GluN2B subunit in the superficial dorsal horn of E2 rats compared to Saff oil rats. Conclusions and inferences These data support the hypothesis that estrogen increases spinal processing of colonic inflammation-induced visceral hyperalgesia by increasing NMDA receptor activity. Specifically, an increase in the activity of GluN2B containing NMDA receptors in the TL spinal cord by estrogen underlies visceral hypersensitivity in the presence of colonic inflammation. PMID:25810326

  9. Spinal microglia initiate and maintain hyperalgesia in a rat model of chronic pancreatitis.

    PubMed

    Liu, Pei-Yi; Lu, Ching-Liang; Wang, Chia-Chuan; Lee, I-Hui; Hsieh, Jen-Chuen; Chen, Chun-Chia; Lee, Hsing-Feng; Lin, Han-Chieh; Chang, Full-Young; Lee, Shou-Dong

    2012-01-01

    The chronic, persistent pain associated with chronic pancreatitis (CP) has many characteristics of neuropathic pain, initiated and maintained by the activation of spinal microglia. We investigated whether activated microglia in the thoracic spinal cord contribute to chronic pain in a rat model of CP. CP was induced in Sprague-Dawley rats by an intraductal injection of 2% trinitrobenzene sulfonic acid. Hyperalgesia was assessed by the measurement of mechanical sensitivity of the abdomen and nocifensive behavior to electrical stimulation of the pancreas. Three weeks after induction of CP, spinal samples were analyzed by immunostaining and immunoblot analyses for levels of CD11 (a marker of microglia, determined with the antibody OX42) and phosphorylated p38 (P-p38, a marker of activation of p38 mitogen-activated protein kinase signaling). We examined the effects of minocycline (inhibitor of microglia) and fractalkine (microglia-activating factor) on visceral hyperalgesia in rats with CP. Rats with CP had increased sensitivity and nociceptive behaviors to mechanical probing of the abdomen and electrical stimulation of the pancreas. The dorsal horn of the thoracic spinal cords of rats with CP contained activated microglia (based on increased staining with OX42), with an ameboid appearance. Levels of P-p38 increased in rats with CP and colocalized with OX42-positive cells. Intrathecal injection of minocycline reversed and prevented the increase of nocifensive behaviors and levels of P-p38 in rats with CP. Fractalkine induced hyperalgesia in rats without CP, which was blocked by minocycline. Activated spinal microglia have important roles in maintaining and initiating chronic pain in a rat model of CP. Microglia might be a target for treatment of hyperalgesia caused by pancreatic inflammation. Copyright © 2012 AGA Institute. Published by Elsevier Inc. All rights reserved.

  10. 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

  11. Spinal 5-HT4 and 5-HT6 receptors contribute to the maintenance of neuropathic pain in rats.

    PubMed

    Pineda-Farias, Jorge Baruch; Barragán-Iglesias, Paulino; Valdivieso-Sánchez, Alann; Rodríguez-Silverio, Juan; Flores-Murrieta, Francisco Javier; Granados-Soto, Vinicio; Rocha-González, Héctor Isaac

    2017-04-04

    Nerve injury promotes release of 5-HT at the spinal cord. Once released, 5-HT may produce antinociceptive or pronociceptive effects depending of the nature of 5-HT receptors. The purpose of this study was to investigate the participation of spinal 5-HT4 and 5-HT6 receptors in the maintenance of neuropathic pain in rats. Tactile allodynia was measured using von Frey hairs in male Wistar rats subjected to L5-L6 spinal nerve injury. Selective 5-HT4 (GR-113808, 0.01-10nmol/rat) and 5-HT6 (SB-258585, 1-1000nmol/rat) receptor antagonists were administered intrathecally to nerve injured rats. Likewise, the most effective dose of 5-HT4 (1nmol/rat) and 5-HT6 (100 nmol/rat) antagonists were co-administered with their respective agonists (ML-10302, 10-100nmol/rat and WAY-208466, 100-1000nmol/rat, respectively). Spinal cord protein expression of both receptors was determined by western blot. Intrathecal administration of 5-HT4 or 5-HT6 receptor antagonists, but not vehicle, decreased in a dose-dependent manner tactile allodynia in neuropathic rats. Moreover, intrathecal co-administration with the agonists prevented in a dose-dependent manner the antagonists-induced antiallodynic effect. Both 5-HT4 and 5-HT6 receptors were expressed in the spinal cord of naïve, sham and neuropathic rats. Nerve injury did not modify expression of any receptor. Data suggests that spinal 5-HT4 and 5-HT6 receptors are expressed in dorsal spinal cord and they participate in the maintenance of neuropathic pain in rats. In this regard, blockade of these receptors could be a useful strategy to treat neuropathic pain states. Copyright © 2017 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  12. 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.

  13. 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

  14. Bladder volume-dependent excitatory and inhibitory influence of lumbosacral dorsal and ventral roots on bladder activity in rats.

    PubMed

    Sugaya, Kimio; de Groat, William C

    2007-08-01

    This study was undertaken to examine the role of the afferent and efferent pathways of the lumbosacral spinal nerve roots in the tonic control of bladder activity. Changes of isovolumetric bladder activity were recorded in 21 sympathectomized female rats under urethane anesthesia following transection of the dorsal (DRT) and ventral (VRT) lumbosacral spinal roots, and after intraperitoneal administration of hexamethonium. DRT altered the baseline intravesical pressure in a bladder volume-dependent manner in each animal. The percent change of baseline pressure after VRT following DRT was also dependent upon bladder volume. The percent change of baseline pressure after VRT alone was similarly dependent on bladder volume, but not after VRT followed by DRT. The percent change of baseline intravesical pressure (y)(-9 to +8 cm H(2)O, -56 to +46%) after DRT and VRT depended upon bladder volume (x)(y = 44.7 x -40.4) in all rats. Hexamethonium increased the amplitude of small myogenic bladder contractions after DRT and VRT. In conclusion, the bladder is tonically excited or inhibited by a local reflex pathway and by a parasympathetic reflex pathway that depends on connections with the lumbosacral spinal cord and the pelvic nerves. Both reflex mechanisms are influenced by bladder volume.

  15. 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

  16. 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

  17. Local anaesthetics block hyperpolarization-activated inward current in rat small dorsal root ganglion neurones

    PubMed Central

    Bischoff, Ulrike; Bräu, Michael E; Vogel, Werner; Hempelmann, Gunter; Olschewski, Andrea

    2003-01-01

    Hyperpolarizing voltage steps evoke slowly activating inward currents in a variety of neurones and in cardiac cells. This hyperpolarization-activated inward current (Ih) is thought to play a significant role in cell excitability, firing frequency, or in setting of the resting membrane potential in these cells. We studied the effects of lidocaine, mepivacaine, QX-314 and bupivacaine as well as its enantiomers on Ih in the membrane of dorsal root ganglion neurones (DRG). The patch-clamp technique was applied to small dorsal root ganglion neurones identified in 200 μM thin slices of young rat DRGs. Under voltage-clamp conditions, the whole-cell Ih current was recorded in the presence of different concentrations of the local anaesthetics. In current-clamp mode the resting membrane potential and the voltage response of DRG neurones to injected current pulses were investigated. Ih was reversibly blocked by bupivacaine, lidocaine and mepivacaine applied externally in clinically relevant concentrations. Concentration–response curves gave half-maximum inhibiting concentrations of 55, 99 and 190 μM, respectively. Bupivacaine block of the Ih current was not stereoselective. No significant effect was observed when QX-314 was applied to the external surface of the membrane. In current-clamp experiments 60 μM bupivacaine slightly hyperpolarized the membrane. The membrane stimulation by low-amplitude current pulses in the presence of bupivacaine showed an increase of the hyperpolarizing responses. Our findings suggest an important role of the Ih-block by local anaesthetics in the complex mechanism of drug action during epidural and spinal anaesthesia. PMID:12890706

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

    PubMed

    Ramasubbu, Chitra; Flagg, Artemus; Williams, Kayode

    2013-02-01

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

  19. Structural and functional alterations of spinal cord axons in adult Long Evans Shaker (LES) dysmyelinated rats.

    PubMed

    Eftekharpour, Eftekhar; Karimi-Abdolrezaee, Soheila; Sinha, Kusum; Velumian, Alexander A; Kwiecien, Jacek M; Fehlings, Michael G

    2005-06-01

    Abnormal formation or loss of myelin is a distinguishing feature of many neurological disorders and contributes to the pathobiology of neurotrauma. In this study we characterize the functional and molecular changes in CNS white matter in Long Evans Shaker (LES) rats. These rats have a spontaneous mutation of the gene encoding myelin basic protein which results in severe dysmyelination of the central nervous system (CNS), providing a unique model for demyelinating/dysmyelinating disorders. To date, the functional and molecular changes in CNS white matter in this model are not well understood. We have used in vivo somatosensory evoked potential (SSEP), in vitro compound action potential (CAP) recording in isolated dorsal columns, confocal immunohistochemistry, Western blotting and real-time PCR to examine the electrophysiological, molecular and cellular changes in spinal cord white matter in LES rats. We observed that dysmyelination is associated with dispersed labeling of Kv1.1 and Kv1.2 K+ channel subunits, as well as Caspr, a protein normally confined to paranodes, along the LES rat spinal cord axons. Abnormal electrophysiological properties including attenuation of CAP amplitude and conduction velocity, high frequency conduction failure and enhanced sensitivity to K+ channel blockers 4-aminopyridine and dendrotoxin-I were observed in spinal cord axons from LES rats. Our results in LES rats clarify some of the key molecular, cellular and functional consequences of dysmyelination and myelin-axon interactions. Further understanding of these issues in this model could provide critical insights for neurological disorders characterized by demyelination.

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

    PubMed

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

    1997-09-08

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

  1. 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.

  2. 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.

  3. 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.

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

    PubMed

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

    2016-10-15

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

  5. A transcription factor network specifying inhibitory versus excitatory neurons in the dorsal spinal cord.

    PubMed

    Borromeo, Mark D; Meredith, David M; Castro, Diogo S; Chang, Joshua C; Tung, Kuang-Chi; Guillemot, Francois; Johnson, Jane E

    2014-07-01

    The proper balance of excitatory and inhibitory neurons is crucial for normal processing of somatosensory information in the dorsal spinal cord. Two neural basic helix-loop-helix transcription factors (TFs), Ascl1 and Ptf1a, have contrasting functions in specifying these neurons. To understand how Ascl1 and Ptf1a function in this process, we identified their direct transcriptional targets genome-wide in the embryonic mouse neural tube using ChIP-Seq and RNA-Seq. We show that Ascl1 and Ptf1a directly regulate distinct homeodomain TFs that specify excitatory or inhibitory neuronal fates. In addition, Ascl1 directly regulates genes with roles in several steps of the neurogenic program, including Notch signaling, neuronal differentiation, axon guidance and synapse formation. By contrast, Ptf1a directly regulates genes encoding components of the neurotransmitter machinery in inhibitory neurons, and other later aspects of neural development distinct from those regulated by Ascl1. Moreover, Ptf1a represses the excitatory neuronal fate by directly repressing several targets of Ascl1. Ascl1 and Ptf1a bind sequences primarily enriched for a specific E-Box motif (CAGCTG) and for secondary motifs used by Sox, Rfx, Pou and homeodomain factors. Ptf1a also binds sequences uniquely enriched in the CAGATG E-box and in the binding motif for its co-factor Rbpj, providing two factors that influence the specificity of Ptf1a binding. The direct transcriptional targets identified for Ascl1 and Ptf1a provide a molecular understanding of how these DNA-binding proteins function in neuronal development, particularly as key regulators of homeodomain TFs required for neuronal subtype specification. © 2014. Published by The Company of Biologists Ltd.

  6. Ablating spinal NK1-bearing neurons eliminates the development of pain and reduces spinal neuronal hyperexcitability and inflammation from mechanical joint injury in the rat.

    PubMed

    Weisshaar, Christine L; Winkelstein, Beth A

    2014-04-01

    The facet joint is a common source of pain, especially from mechanical injury. Although chronic pain is associated with altered spinal glial and neuronal responses, the contribution of specific spinal cells to joint pain is not understood. This study used the neurotoxin [Sar(9),Met(O2)(11)]-substance P-saporin (SSP-SAP) to selectively eliminate spinal cells expressing neurokinin-1 receptor (NK1R) in a rat model of painful facet joint injury to determine the role of those spinal neurons in pain from facet injury. Following spinal administration of SSP-SAP or its control (blank-SAP), a cervical facet injury was imposed and behavioral sensitivity was assessed. Spinal extracellular recordings were made on day 7 to classify neurons and quantify evoked firing. Spinal glial activation and interleukin 1αα (IL1α) expression also were evaluated. SSP-SAP prevented the development of mechanical hyperalgesia that is induced by joint injury and reduced NK1R expression and mechanically evoked neuronal firing in the dorsal horn. SSP-SAP also prevented a shift toward wide dynamic range neurons that is seen after injury. Spinal astrocytic activation and interleukin 1α (IL1α) expression were reduced to sham levels with SSP-SAP treatment. These results suggest that spinal NK1R-bearing cells are critical in initiating spinal nociception and inflammation associated with a painful mechanical joint injury. Results demonstrate that cells expressing NK1R in the spinal cord are critical for the development of joint pain, spinal neuroplasticity, and inflammation after trauma to the joint. These findings have utility for understanding mechanisms of joint pain and developing potential targets to treat pain. Copyright © 2014 American Pain Society. Published by Elsevier Inc. All rights reserved.

  7. Forced treadmill running suppresses postincisional pain and inhibits upregulation of substance P and cytokines in rat dorsal root ganglion.

    PubMed

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

    2014-08-01

    Exercise causes a variety of psychophysical effects (eg, alterations in pain sensation). Tissue injury induces mediator releases in the spinal cord resulting in pain hypersensitivity; however, the contribution of the dorsal root ganglion (DRG) is poorly understood. In this study, we tested if forced treadmill running can attenuate postoperative pain and alter substance P (SP) or proinflammatory cytokine level in the DRG by using a rat model of skin/muscle incision and retraction (SMIR). We evaluated mechanical sensitivity to von Frey stimuli (6 and 15 g) and expression of SP, interleukin-1β, and interleukin-6 in the DRG of sham-operated sedentary rats, SMIR sedentary rats, sham-operated rats with forced treadmill running, and SMIR rats with forced treadmill running. At postoperative day 8, trained rats ran for 5 days per week for 4 weeks on a treadmill 70 minutes/d with an intensity of 18 m/min. On postoperative day 6, SMIR sedentary rats displayed a significant mechanical hypersensitivity that persisted until postoperative day 35. By comparison, SMIR-operated rats, which received forced treadmill running, exhibited a quick recovery from mechanical hypersensitivity. SMIR sedentary rats showed an upregulation of SP, interleukin-1β, and interleukin-6 in the DRG at postoperative days 14 and 28, whereas SMIR-operated rats receiving forced treadmill running reversed this upregulation at postoperative day 28. We concluded that forced treadmill running alleviated persistent postincisional pain caused by SMIR surgery. This appears to be protective against postoperative pain, which probably relates to the downturn in excess SP, interleukin-1β, and interleukin-6 in the DRG. Controlling the expression of SP, interleukin-6, and interleukin-1β in the DRG can help manage postoperative pain. This finding could potentially help clinicians and physical therapists who seek to examine how exercise may attenuate postsurgical pain and its mechanism. Copyright © 2014 American Pain

  8. 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.

  9. 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.

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

    PubMed

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

    2016-08-01

    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.

  11. 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

  12. Canonical BMP7 activity is required for the generation of discrete neuronal populations in the dorsal spinal cord

    PubMed Central

    Le Dréau, Gwenvael; Garcia-Campmany, Lidia; Rabadán, M. Angeles; Ferronha, Tiago; Tozer, Samuel; Briscoe, James; Martí, Elisa

    2012-01-01

    BMP activity is essential for many steps of neural development, including the initial role in neural induction and the control of progenitor identities along the dorsal-ventral axis of the neural tube. Taking advantage of chick in ovo electroporation, we show a novel role for BMP7 at the time of neurogenesis initiation in the spinal cord. Using in vivo loss-of-function experiments, we show that BMP7 activity is required for the generation of three discrete subpopulations of dorsal interneurons: dI1-dI3-dI5. Analysis of the BMP7 mouse mutant shows the conservation of this activity in mammals. Furthermore, this BMP7 activity appears to be mediated by the canonical Smad pathway, as we demonstrate that Smad1 and Smad5 activities are similarly required for the generation of dI1-dI3-dI5. Moreover, we show that this role is independent of the patterned expression of progenitor proteins in the dorsal spinal cord, but depends on the BMP/Smad regulation of specific proneural proteins, thus narrowing this BMP7 activity to the time of neurogenesis. Together, these data establish a novel role for BMP7 in primary neurogenesis, the process by which a neural progenitor exits the cell cycle and enters the terminal differentiation pathway. PMID:22159578

  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. Release of GABA and activation of GABAA in the spinal cord mediates the effects of TENS in rats

    PubMed Central

    Maeda, Y.; Lisi, T.L.; Vance, C.G.T.; Sluka, K.A.

    2009-01-01

    Transcutaneous electrical nerve stimulation (TENS) is a commonly utilized non-pharmacological, non-invasive treatment for pain. GABA is a neurotransmitter in the dorsal horn of the spinal cord that mediates analgesia locally, and also through activation of supraspinal sites. TENS reduces hyperalgesia through activation of receptor-mediated pathways at the level of the spinal cord, and supraspinally. The current study tested the hypothesis that either high or low frequency TENS applied to the inflamed knee joint increases GABA in the spinal cord dorsal horn and activates GABA receptors spinally. We utilized microdialysis to sample the extracellular fluid before, during and after TENS and analyzed GABA in dialysates with high performance liquid chromatography. We analyzed the extracellular GABA concentrations in animals with and without knee joint inflammation induced by intra-articular injection of kaolin and carrageenan. We further tested if spinal blockade of GABA receptors prevents the antihyperalgesia produced by TENS in rats with joint inflammation. We show that high frequency TENS increases extracellular GABA concentrations in the spinal cord in animals with and without joint inflammation. The increases in GABA do not occur in response to low frequency TENS, and there are no increases in glycine in response to low or high frequency TENS. However, the reduction in primary hyperalgesia by both high and low frequency TENS is prevented by spinal blockade of GABAA receptors with bicuculline. Thus, high frequency TENS increases release of GABA in the deep dorsal horn of the spinal cord, and both high and low frequency TENS reduce primary hyperalgesia by activation of GABAA receptors spinally. PMID:17234163

  16. Serotonin increases the incidence of primary afferent-evoked long-term depression in rat deep dorsal horn neurons.

    PubMed

    Garraway, S M; Hochman, S

    2001-05-01

    5-hydroxytryptamine (5-HT) is released in spinal cord by descending systems that modulate somatosensory transmission and can potently depress primary afferent-evoked synaptic responses in dorsal horn neurons. Since primary afferent activity-induced long-term potentiation (LTP) may contribute to central sensitization of nociception, we studied the effects of 5-HT on the expression of sensory-evoked LTP and long-term depression (LTD) in deep dorsal horn (DDH) neurons. Whole cell, predominantly current clamp, recordings were obtained from DDH neurons in transverse slices of neonatal rat lumbar spinal cord. The effect of 5-HT on dorsal-root stimulation-evoked synaptic responses was tested before, during, or after high-frequency conditioning stimulation (CS). In most cells (80%), 5-HT caused a depression of the naïve synaptic response. Even though 5-HT depressed evoked responses, CS in the presence of 5-HT was not only still capable of inducing LTD but also increased its incidence from 54% in controls to 88% (P < 0.001). Activation of ligands selective for 5-HT(1A/1B) and 5-HT(1B), but not 5-HT(2A/2C) or 5-HT(3) receptors, best reproduced these actions. 5-HT also potently depressed postconditioning synaptic responses regardless of whether the induced plasticity was LTP or LTD. Our results demonstrate that in addition to depressing the amplitude of evoked sensory input, 5-HT can also control the direction of its long-term modifiability, favoring the expression of LTD. These findings demonstrate cellular mechanisms that may contribute to the descending serotonergic control of nociception.

  17. 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

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

    NASA Astrophysics Data System (ADS)

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

    1992-12-01

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

  19. Role of supraspinal and spinal alpha1-adrenergic receptor subtypes in micturition reflex in conscious rats.

    PubMed

    Yoshizumi, Masaru; Matsumoto-Miyai, Kazumasa; Yonezawa, Akihiko; Kawatani, Masahito

    2010-10-01

    α(1)-Adrenergic receptor subtypes are widely distributed in the central nervous system and are involved in autonomic functions such as micturition. We investigated the presence and the role of supraspinal and/or spinal α(1)-adrenergic receptors in modulating the micturition reflex in conscious female Wistar rats. The expression of α(1)-adrenergic receptor subtypes in rat brain and lumbosacral spinal cord was studied using RT-PCR. Continuous-infusion cystometrograms were obtained in conscious rats, and α(1)-adrenergic receptor antagonists were administered via intracerebroventricular or intrathecal routes. The mRNA expression of α(1A)-, α(1B)-, and α(1D)-adrenergic receptors was detected in rat brain (midbrain and pons) and lumbosacral spinal cord (dorsal and ventral parts of spinal cord). In addition, intracerebroventricular injection of the α(1)-adrenergic receptor antagonist tamsulosin (1-10 μg), the selective α(1A)-adrenergic receptor antagonist silodosin (1-10 μg), and the selective α(1D)-adrenergic receptor antagonist BMY 7378 (1-10 μg) significantly prolonged the intercontraction interval (ICI) but did not alter maximum voiding pressure (MVP). Although intrathecal injection of BMY 7378 (0.0001-10 μg) did not affect ICI, tamsulosin and silodosin prolonged ICI in a dose-dependent manner. MVP was significantly reduced by intrathecal injection of tamsulosin (10 μg) but not by silodosin or BMY 7378 (0.0001-10 μg). Supraspinal α(1A)- and α(1D)-adrenergic receptors are apparently important for the regulation of reflex-bladder activity in conscious rats. Noradrenergic projection from the brain stem to the lumbosacral spinal cord may promote the afferent limb rather than the efferent limb of the micturition reflex pathway via α(1A)-adrenergic receptors.

  20. 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.

  1. 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

  2. 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

  3. 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

  4. 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.

  5. Muscle afferent excitability testing in spinal root-intact rats: dissociating peripheral afferent and efferent volleys generated by intraspinal microstimulation.

    PubMed

    Tomatsu, Saeka; Kim, Geehee; Confais, Joachim; Seki, Kazuhiko

    2017-02-01

    Presynaptic inhibition of the sensory input from the periphery to the spinal cord can be evaluated directly by intra-axonal recording of primary afferent depolarization (PAD) or indirectly by intraspinal microstimulation (excitability testing). Excitability testing is superior for use in normal behaving animals, because this methodology bypasses the technically challenging intra-axonal recording. However, use of excitability testing on the muscle or joint afferent in intact animals presents its own technical challenges. Because these afferents, in many cases, are mixed with motor axons in the peripheral nervous system, it is crucial to dissociate antidromic volleys in the primary afferents from orthodromic volleys in the motor axon, both of which are evoked by intraspinal microstimulation. We have demonstrated in rats that application of a paired stimulation protocol with a short interstimulus interval (ISI) successfully dissociated the antidromic volley in the nerve innervating the medial gastrocnemius muscle. By using a 2-ms ISI, the amplitude of the volleys evoked by the second stimulation was decreased in dorsal root-sectioned rats, but the amplitude did not change or was slightly increased in ventral root-sectioned rats. Excitability testing in rats with intact spinal roots indicated that the putative antidromic volleys exhibited dominant primary afferent depolarization, which was reasonably induced from the more dorsal side of the spinal cord. We concluded that excitability testing with a paired-pulse protocol can be used for studying presynaptic inhibition of somatosensory afferents in animals with intact spinal roots.NEW & NOTEWORTHY Excitability testing of primary afferents has been used to evaluate presynaptic modulation of synaptic transmission in experiments conducted in vivo. However, to apply this method to muscle afferents of animals with intact spinal roots, it is crucial to dissociate antidromic and orthodromic volleys induced by spinal

  6. 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

  7. The influence of cervical spinal cord compression and vertebral displacement on somatosympathetic reflexes in the rat.

    PubMed

    Bigland, Mark J; Budgell, Brian S; Bolton, Philip S

    2015-06-01

    One theory within chiropractic proposes that vertebral subluxation in the upper cervical region induces spinal cord compression sufficient to alter spinal cord efferent output. We report on the feasibility of three different experimental approaches to test this theory. A high threshold electrical-evoked somatosympathetic reflex was recorded in adrenal or renal nerves of 10 anaesthetized adult male rats before and after (1) graded pressure was applied directly to the C1/C2 spinal cord segment in eight rats by the use of either direct compression or inflation of an extradural balloon and (2) displacement, less than a dislocation applied posterior to anterior, to the C2 vertebra in two rats. The latency and amplitude of the pre- and postintervention reflex responses were compared. The reflex amplitude was not significantly changed by pressure (26 mmHg) from an extra-dural balloon or direct compression of the dura mater onto the dorsal spinal cord. Additional pressure, at least sufficient to occlude the dorsal vessels, induced a significant reduction in the amplitude of the reflex, and this reduction persisted for 20 minutes after removal of the pressure (Dunn's method for all pairwise multiple comparison Q stat=3.437; critical value for k=6 with α=0.05 is 2.936). Maximal vertebral (C2) displacement (4 mm), without dislocation did not induce significant changes compared with the control period. Although this feasibility study suggests it is unlikely that upper cervical vertebral subluxation, displacement less than a dislocation, compromises the sympathetic outflow in the adrenal or renal nerves, further vertebral displacement studies are necessary to formally test this. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. [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.

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

    PubMed Central

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

    2012-01-01

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

  10. 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

  11. Permanent loss of fore-paw grasping requires complete deprivation of afferent input from a minimum of four dorsal roots of the rat brachial plexus.

    PubMed

    Ibrahim, Ahmed G; Raisman, Geoffrey; Li, Ying

    2009-01-01

    Dorsal roots from the 6th cervical to the 1st thoracic segment were sectioned flush with the surface of the spinal cord on one side. For 3 weeks before and 8 weeks after surgery the rats were filmed once a week during two successive climbs up a 1 m grid. Before surgery the fore-paws of normal rats grasped the grid bar for a mean of 7.0+/-0.1 times per climb. After complete section of C6 to T1 dorsal roots on one side there was a major deficit in the ipsilateral fore-paw in locating the grid bars, and grasping was almost totally abolished (mean of 0.1+/-0.06 grasps per climb). The failure of the rats to locate or to grasp the bars persisted unchanged for the entire test period. Rats with section of C6 to C8, but sparing T1, showed a similar but milder pattern of deficit. Section of any two adjacent cervical roots caused only minor deficits. Section of any single root alone caused no detectable deficit in climbing. The consistent loss of grasping after section of the 4 dorsal roots from C6 to T1 provides a promising model for assessing putative regenerative therapies.

  12. 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.

  13. 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

  14. 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

  15. Spinal translocator protein (TSPO) modulates pain behavior in rats with CFA-induced monoarthritis.

    PubMed

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

    2009-08-25

    Translocator protein 18 kDa (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 Days 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 laminae I-II on all experimental days. Iba-1 expression in the ipsilateral dorsal horn was also increased on Days 7 and 14. Moreover, TSPO was colocalized 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.

  16. [The changes of monocarboxylate transporter-2 in spinal cord horn in a rat model of chronic inflammatory pain].

    PubMed

    He, Jian-hua; Xu, Li; Shen, Yu; Kong, Ming-jian; Shi, Lin-yu; Ma, Zheng-liang

    2015-01-01

    To investigate the changes in the levels of monocarboxylate transporter-2 in spinal cord horn in a rat model of chronic inflammatory pain. Male SD rats weighting 180 - 220 g were randomly divided into two groups(n = 48): normal saline group (NS group), complete Freund's adjuvant group (CFA group). Rats were given injections of CFA 100 µl in left hind paw in group CFA, and an equal volume of saline was given injection in group NS. Mechanical withdraw threshold(MWT) and thermal withdraw latency(TWL) were measured at before injection(T0 and 3 h, 1 d, 3 d, 7 d, 14 d, and 21 d after injection(T1-7). Four rats were chosen from each group at T0-7 and sacrificed, and L4-5 segments of the spinal cord horn were removed for measurement of the expression of monocarboxylate transporter-2 by Western blot analysis. In CFA group, mechanical hyperalgesia and allodynia appeared on the 3 h after CFA injection, then until the day 14. The expression of monocarboxylate transporter-2 in the spinal dorsal horn of rats in CFA group was significantly higher than that in normal control group at T1-6(P <0.05). The protein level of monocarboxylate transporter-2 was apparently correlated with MWT and TWL(P <0.01 and P <0.05) in CFA group. The level of monocarboxylate transporter-2 in spinal dorsal horn is significantly increased in a rat model of chronic inflammatory pain and the change may involve in the formation and maintenance of central sensitization in spinal cord of chronic inflammatory uain.

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

    PubMed Central

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

    2009-01-01

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

  18. 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.

  19. 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

  20. Coital Urinary Incontinence Induced by Impairment of the Dorsal Nerve of the Clitoris in Rats.

    PubMed

    Cruz, Yolanda; Juárez, Raúl; Medel, Alfonso; Corona-Quintanilla, Dora Luz; Pacheco, Pablo; Juárez, Margarita

    2016-02-01

    We determined the effect of chronic bilateral neurectomy of the dorsal nerve of the clitoris on urinary parameters and sexual behavior of conscious female rats. A total of 18 anesthetized virgin female Wistar rats were used in this study, including 11 that underwent bilateral neurectomy of the dorsal nerve of the clitoris and 7 that underwent sham surgery. Urinary parameters were determined in awake animals preoperatively, and 3 and 10 days postoperatively. Sexual behavior was tested 14 days postoperatively to determine whether the females expelled urine during sexual encounters. After male ejaculation the females were anesthetized with urethane to record external urethral sphincter electromyogram activity in response to clitoris, perigenital skin and vaginal stimulation. Neurectomy was corroborated anatomically. Sham surgery did not significantly modify urinary parameter values. However, bilateral neurectomy of the dorsal nerve of the clitoris significantly increased voiding frequency and voiding duration (p <0.05). It did not significantly affect the flow rate, voided volume or voiding interval. Of females that underwent bilateral neurectomy of the dorsal nerve of the clitoris 67% expelled urine just after male ejaculation. These results suggest that the pudendal nerve is an important neural pathway in the convergence and crosstalk of female urogenital neural circuits, and genital deafferentation may be a causal factor of coital urinary incontinence. Rats with bilateral transection of the dorsal nerve of the clitoris may serve as an animal model of coital incontinence. Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  1. 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.

  2. 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

  3. Effects of simulated weightlessness on intramuscular hypertonic saline induced muscle nociception and spinal Fos expression in rats.

    PubMed

    Lei, Jing; Pertovaara, Antti; You, Hao-Jun

    2015-01-12

    We assessed the effects of simulated weightlessness, hindlimb unloading (HU) by 7 days of tail suspension, on noxious mechanically and heat evoked spinal withdrawal reflexes and spinal Fos expression during muscle nociception elicited by intramuscular (i.m.) injection of hypertonic (HT; 5.8%) saline into gastrocnemius muscle in rats. In HU rats, i.m. HT saline-induced secondary mechanical hyperalgesia was enhanced, and secondary heat hypoalgesia was significantly delayed. After 7 days of HU, basal Fos expression in spinal L4-6 segments was bilaterally enhanced only in superficial (I-II) but not middle and deep laminae (III-VI) of the spinal dorsal horn, which finding was not influenced by tail denervation. Unilateral i.m. HT saline injection increased spinal Fos expression bilaterally in both the control rats and 7 days of HU rats. The HT saline-induced bilateral increase of spinal Fos occurred within 0.5h and reached its peak within 1h, after which it gradually returned to the control levels within 8h. Spatial patterns of spinal Fos expression differed between the control group and 7 days of HU group. In superficial laminae, the HT saline-induced increases in Fos expression were higher and in the middle and deep laminae V-VI lower in the 7 days of HU than control rats. It is suggested that supraspinal mechanisms presumably underlie the effects of HU on spinally-organized nociception. Simulated weightlessness may enhance descending facilitation and weaken descending inhibition of nociception. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. 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

  5. [Expression of hemokinin-1 in rat spinal cord after peripheral inflammation].

    PubMed

    Ando, Yuko

    2009-06-01

    Hemokinin-1 (HK-1) is a novel peptide described as a member of the tachykinin family. Substance P (SP), a representative member of the tachykinin family, has been well characterized and is thought to play a part in inflammation and pain. While several studies indicate that HK-1 is involved in inflammation and pain, the biological functions of HK-1 are not fully understood. In the present study we investigated the expression of HK-1 mRNA (TAC4) and SP mRNA (TAC1) in the dorsal spinal cord of rat after inducing peripheral inflammation by administering complete Freund's adjuvant (CFA) into the hind paw, using real-time RT-PCR. In the behavioral studies, the thresholds of withdrawal response of the hind paw to thermal stimulation significantly decreased on the ipsilateral side, but not on the contralateral side, 6 hours after CFA injection and thermal hyperalgesia persisted until 4 days after CFA injection. The level of HK-1 mRNA expression significantly increased on the bilateral sides of the dorsal spinal cord 6 hours after CFA injection and returned to the base level 1 day after injection. On the other hand, the level of SP mRNA expression did not change in the spinal cord 6 hours and 1 day after CFA injection. These results indicate that HK-1 may contribute to inflammatory pain, in the early phase, in a different manner from SP.

  6. 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

  7. 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.

  8. 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.

  9. 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.

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

    PubMed

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

    2015-05-01

    Visceral hypersensitivity represents an important hallmark in the pathophysiology of irritable bowel syndrome (IBS), of which the mechanisms remain elusive. The present study was designed to examine whether cation-chloride cotransporter (CCC)-mediated chloride (Cl(-)) homeostasis of the spinal cord is involved in chronic stress-induced visceral hypersensitivity. Chronic visceral hypersensitivity was induced by exposing male Wistar rats to water avoidance stress (WAS). RT-PCR, Western blotting, and immunohistochemistry were used to assess the expression of CCCs in the spinal cord. Patch-clamp recordings were performed on adult spinal cord slices to evaluate Cl(-) homeostasis and Cl(-) extrusion capacity of lamina I neurons. Visceral sensitivity was estimated by measuring the abdominal withdrawal reflex in response to colorectal distension (CRD). After 10 days of WAS exposure, levels of both total protein and the oligomeric form of the K(+)-Cl(-) cotransporter isoform 2 (KCC2), but not Na(+)-K(+)-2Cl(-) transporter isoform 1 (NKCC1), were significantly decreased in the dorsal horn of the lumbosacral spinal cord. The downregulation of KCC2 resulted in a depolarizing shifted equilibrium potential of GABAergic inhibitory postsynaptic current and impaired Cl(-) extrusion capacity in lamina I neurons of the lumbosacral spinal cord from WAS rats. Acute noxious CRD disrupted spinal KCC2 expression and function 2 h after the final distention in sham rats, but not in WAS rats. Pharmacological blockade of KCC2 activity by intrathecal injection of a KCC2 inhibitor [(dihydroindenyl)oxy] alkanoic acid enhanced visceral nociceptive sensitivity in sham rats, but not in WAS rats. These results suggest that KCC2 downregulation-mediated impairment of spinal cord Cl(-) homeostasis may play an important role in chronic stress-induced visceral hypersensitivity. Copyright © 2015 the American Physiological Society.

  11. 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.

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

    PubMed

    Qi, Hui-Xin; Chen, Li M; Kaas, Jon H

    2011-09-21

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

  13. 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

  14. 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

  15. Effect of interleukin-1β on spinal cord nociceptive transmission of normal and monoarthritic rats after disruption of glial function

    PubMed Central

    Constandil, Luis; Hernández, Alejandro; Pelissier, Teresa; Arriagada, Osvaldo; Espinoza, Karla; Burgos, Hector; Laurido, Claudio

    2009-01-01

    Introduction Cytokines produced by spinal cord glia after peripheral injuries have a relevant role in the maintenance of pain states. Thus, while IL-1β is overexpressed in the spinal cords of animals submitted to experimental arthritis and other chronic pain models, intrathecal administration of IL-1β to healthy animals induces hyperalgesia and allodynia and enhances wind-up activity in dorsal horn neurons. Methods To investigate the functional contribution of glial cells in the spinal cord nociceptive transmission, the effect of intrathecally administered IL-1β was studied in both normal and adjuvant-induced arthritic rats with or without glial inhibition. Four weeks after induction of monoarthritis, rats were treated with the glial cell inhibitor propentofylline (10 μg i.t. daily during 10 days) and submitted to a C-fiber-mediated reflex paradigm evoked by single and repetitive (wind-up) electric stimulation. Results Both the propentofylline treatment and the monoarthritic condition modified the stimulating current required for threshold activation of C reflex responses. Intrathecal IL-1β increased spinal cord wind-up activity in normal and monoarthritic rats without propentofylline pre-treatment, but resulted in decreased wind-up activity in normal and monoarthritic propentofylline-treated animals. Intrathecal saline did not produce any effect. Thus, glial inactivation reverted into inhibition the excitatory effect of IL-1β on spinal cord wind-up, irrespective of the normal or monoarthritic condition of rats. Conclusions The results suggest that the excitatory effect of nanomolar doses of IL-1β on spinal wind-up in healthy rats is produced by an unidentified glial mediator, while the inhibitory effects of IL-1β on wind-up activity in animals with inactivated glia resulted from a direct effect of the cytokine on dorsal horn neurons. The present study failed to demonstrate a differential sensitivity of normal and monoarthritic rats to IL-1β administration

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. Alterations in the neural circuits from peripheral afferents to the spinal cord: possible implications for diabetic polyneuropathy in streptozotocin-induced type 1 diabetic rats

    PubMed Central

    Kou, Zhen-Zhen; Li, Chun-Yu; Hu, Jia-Chen; Yin, Jun-Bin; Zhang, Dong-Liang; Liao, Yong-Hui; Wu, Zhen-Yu; Ding, Tan; Qu, Juan; Li, Hui; Li, Yun-Qing

    2014-01-01

    Diabetic polyneuropathy (DPN) presents as a wide variety of sensorimotor symptoms and affects approximately 50% of diabetic patients. Changes in the neural circuits may occur in the early stages in diabetes and are implicated in the development of DPN. Therefore, we aimed to detect changes in the expression of isolectin B4 (IB4, the marker for nonpeptidergic unmyelinated fibers and their cell bodies) and calcitonin gene-related peptide (CGRP, the marker for peptidergic fibers and their cell bodies) in the dorsal root ganglion (DRG) and spinal cord of streptozotocin (STZ)-induced type 1 diabetic rats showing alterations in sensory and motor function. We also used cholera toxin B subunit (CTB) to show the morphological changes of the myelinated fibers and motor neurons. STZ-induced diabetic rats exhibited hyperglycemia, decreased body weight gain, mechanical allodynia and impaired locomotor activity. In the DRG and spinal dorsal horn, IB4-labeled structures decreased, but both CGRP immunostaining and CTB labeling increased from day 14 to day 28 in diabetic rats. In spinal ventral horn, CTB labeling decreased in motor neurons in diabetic rats. Treatment with intrathecal injection of insulin at the early stages of DPN could alleviate mechanical allodynia and impaired locomotor activity in diabetic rats. The results suggest that the alterations of the neural circuits between spinal nerve and spinal cord via the DRG and ventral root might be involved in DPN. PMID:24523675

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

    PubMed Central

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

    2011-01-01

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

  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. Gabapentin reduces CX3CL1 signaling and blocks spinal microglial activation in monoarthritic rats

    PubMed Central

    2012-01-01

    Background Spinal glia, particularly microglia and astrocytes, are of the utmost importance in the development and maintenance of chronic pain. A recent study from our laboratory revealed that gabapentin, a recommended first-line treatment for multiple neuropathic conditions, could also efficiently antagonize thermal hyperalgesia evoked by complete Freund's adjuvant (CFA)-induced monoarthritis (MA). In the present study, we investigated whether the spinal glia are involved in the anti-hyperalgesic effect of gabapentin and how this event occurs. Results Unilateral intra-articular injection of CFA produced a robust activation of microglia and astrocytes. These cells exhibited large cell bodies, thick processes and increases in the ionized calcium binding adapter molecule 1 (Iba-1, a microglial marker) or the glia fibrillary acidic protein (GFAP, an astrocytic marker). These cells also displayed immunoreactive signals, and an upregulation of the voltage-gated calcium channels (VGCCs) α2/δ-1 subunit, CX3CL1 and CX3CR1 expression levels in the spinal cord. These changes were associated with the development of thermal hyperalgesia. Immunofluorescence staining showed that VGCC α2/δ-1 subunit, a proposed gabapentin target of action, was widely distributed in primary afferent fibers terminals and dorsal horn neurons. CX3CL1, a potential trigger to activate microglia, colocalized with VGCC α2/δ-1 subunits in the spinal dorsal horn. However, its receptor CX3CR1 was mainly expressed in the spinal microglia. Multiple intraperitoneal (i.p.) gabapentin injections (100 mg/kg, once daily for 4 days with the first injection 60 min before intra-articular CFA) suppressed the activation of spinal microglia, downregulated spinal VGCC α2/δ-1 subunits decreased CX3CL1 levels and blocked the development of thermal hyperalgesia in MA rats. Conclusions Here we provide the first evidence that gabapentin diminishes CX3CL1 signaling and spinal microglia activation induced by joint

  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. 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

  6. 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

  7. 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.

  8. The effect of fentanyl, DNQX and MK-801 on dorsal horn neurones responsive to colorectal distension in the anaesthetized rat.

    PubMed

    Kozlowski, C M; Bountra, C; Grundy, D

    2000-06-01

    Certain dorsal horn neurones respond in a graded manner to noxious colorectal distension (CRD). Morphine inhibits these responses in the spinalized rat, but the role of excitatory amino acids in baseline visceral nociceptive transmission is less clear. This study examines the effect of the mu-opiate receptor agonist fentanyl, and the non-NMDA and NMDA antagonists DNQX and MK-801, respectively, on such responses to CRD in the sodium pentobarbitone-anaesthetized rat. Male rats were prepared for extracellular recording from the lumbosacral spinal cord. 90 neurones responsive to CRD, located throughout the dorsal horn, were classified according to their response duration and latency to 60 mmHg distension, as SL-A (short latency-abrupt; 59%), SL-S (short latency-sustained; 23%), L-L (long-latency; 10%) and Inhib (inhibited; 8%). Convergent cutaneous receptive fields were mapped for 79/90 neurones and classified as LT (low threshold), WDR (wide dynamic range) or HT (high threshold). CRD (20-100 mm Hg) elicited graded responses in most neurones. In 6/6 SL-S neurones, fentanyl (1-8 microg kg-1) dose-dependently inhibited the response to 60 mm Hg CRD, in a naloxone-sensitive manner, with an ID50 value (+/-95% confidence limits) of 2.48 (1.7-3. 7) microg kg-1. In 6/6 SL-A neurones, fentanyl had no significant effect on the response to CRD. DNQX (0.03-3 mg kg-1) produced a dose-dependent inhibition of the response to CRD in 5/5 SL-A neurones, with an ID50 value of 0.32 (0.01-41.1) mg kg-1. MK-801 (0. 03-0.3 mg kg-1) had no significant effect on responses to CRD in 6/6 SL-A neurones. The differential inhibitory effects of fentanyl on two neuronal subtypes may indicate functional differences. In SL-A neurones AMPA/kainate, but not NMDA receptors are involved in mediating baseline nociceptive neurotransmission.

  9. Stereotactic radiosurgery improves locomotor recovery after spinal cord injury in rats.

    PubMed

    Zeman, Richard J; Wen, Xialing; Ouyang, Nengtai; Rocchio, Ronald; Shih, Lynn; Alfieri, Alan; Moorthy, Chitti; Etlinger, Joseph D

    2008-11-01

    Currently, because of the precision of stereotactic radiosurgery, radiation can now be delivered by techniques that shape the radiation beam to the tissue target for a variety of clinical applications. This avoids unnecessary and potentially damaging irradiation of surrounding tissues inherent in conventional irradiation, so that irradiation of the minimum volume of tissue necessary for optimal therapeutic benefit can be achieved. Although conventional x-irradiation has been shown to improve recovery from spinal cord injury in animals, the efficacy of targeted irradiation of the injured spinal cord has not been demonstrated previously. The purpose of these studies was to determine whether stereotactic x-irradiation of the injured spinal cord can enhance locomotor function and spare spinal cord tissue after contusion injury in a standard experimental model of spinal cord injury. Contusion injury was produced in rats at the level of T10 with a weight-drop device, and doses of x-irradiation were delivered 2 hours after injury via a Novalis, 6-MeV linear accelerator shaped beam radiosurgery system (BrainLAB USA, Westchester, IL) in 4 sequential fractions, with beam angles 60 to 70 degrees apart, at a rate of 6.4 Gy/minute. The target volume was a 4 x 15-mm cylinder along the axis of the spinal cord, with the isocenter positioned at the contusion epicenter. Locomotor function was determined for 6 weeks after injury with the 21-point Basso, Beattie, and Bresnahan (BBB) locomotor scale and tissue sparing in histological sections of the spinal cord. Locomotor function recovered progressively during the 6-week postinjury observation period. BBB scores were significantly greater in the 10-Gy x-irradiated group compared with controls (9.4 versus 7.3; P < 0.05), indicating hind limb weight support or dorsal stepping in contrast to hind limb joint mobility without weight bearing. Doses in the range of 2 to 10 Gy increased BBB scores progressively, whereas greater doses of 15 to

  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. 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.

  12. 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

  13. 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.

  14. 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

  15. Role of anoctamin-1 and bestrophin-1 in spinal nerve ligation-induced neuropathic pain in rats.

    PubMed

    Pineda-Farias, Jorge Baruch; Barragán-Iglesias, Paulino; Loeza-Alcocer, Emanuel; Torres-López, Jorge E; Rocha-González, Héctor Isaac; Pérez-Severiano, Francisca; Delgado-Lezama, Rodolfo; Granados-Soto, Vinicio

    2015-07-01

    Calcium-activated chloride channels (CaCCs) activation induces membrane depolarization by increasing chloride efflux in primary sensory neurons that can facilitate action potential generation. Previous studies suggest that CaCCs family members bestrophin-1 and anoctamin-1 are involved in inflammatory pain. However, their role in neuropathic pain is unclear. In this investigation we assessed the involvement of these CaCCs family members in rats subjected to the L5/L6 spinal nerve ligation. In addition, anoctamin-1 and bestrophin-1 mRNA and protein expression in dorsal root ganglion (DRG) and spinal cord was also determined in the presence and absence of selective inhibitors. L5/L6 spinal nerve ligation induced mechanical tactile allodynia. Intrathecal administration of non-selective CaCCs inhibitors (NPPB, 9-AC and NFA) dose-dependently reduced tactile allodynia. Intrathecal administration of selective CaCCs inhibitors (T16Ainh-A01 and CaCCinh-A01) also dose-dependently diminished tactile allodynia and thermal hyperalgesia. Anoctamin-1 and bestrophin-1 mRNA and protein were expressed in the dorsal spinal cord and DRG of naïve, sham and neuropathic rats. L5/L6 spinal nerve ligation rose mRNA and protein expression of anoctamin-1, but not bestrophin-1, in the dorsal spinal cord and DRG from day 1 to day 14 after nerve ligation. In addition, repeated administration of CaCCs inhibitors (T16Ainh-A01, CaCCinh-A01 or NFA) or anti-anoctamin-1 antibody prevented spinal nerve ligation-induced rises in anoctamin-1 mRNA and protein expression. Following spinal nerve ligation, the compound action potential generation of putative C fibers increased while selective CaCCs inhibitors (T16Ainh-A01 and CaCCinh-A01) attenuated such increase. There is functional anoctamin-1 and bestrophin-1 expression in rats at sites related to nociceptive processing. Blockade of these CaCCs suppresses compound action potential generation in putative C fibers and lessens established tactile allodynia

  16. Acute DSS colitis alters EphB6 receptor expression in neurons of the spinal dorsal horn.

    PubMed

    King, Dale E

    2014-01-24

    The ephrin family of receptors (Eph) and their ephrin ligands are involved in pain associated hyperalgesia, but the underlying mechanisms involved have not been fully elucidated. The EphB6 receptor is a distinctive member of the EphB subclass in that its kinase domain contains several alterations in the conserved amino acids and thus lacks catalytic activity. We sought to identify a role for EphB6 in inflammatory pain, with the murine dextran sulfate sodium (DSS) colitis model of inflammatory bowel disease (IBD). Colitis, induced with the administration of 4% (wt./vol.) DSS in the drinking water, significantly decreased EphB6 protein expression levels in neurons of the lower thoracic superficial layers of spinal dorsal horns, the location of neurons that receive the majority of nociceptive information from the colon, via the primary afferents. A shift towards increased EphB/ephrinB forward signaling, mediated by EphB6 down-regulation in neurons of the dorsal horn, may play a role in inflammatory pain caused by IBD. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

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

    PubMed Central

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

    2016-01-01

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

  18. 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.

  19. 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. Copyright © 2014 Elsevier B.V. All rights reserved.

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

    PubMed

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

    2016-08-04

    The spinal dorsal horn processes somatosensory information before conveying it to the brain. The neuronal organization of the dorsal horn is still poorly understood, although recent studies have defined several distinct populations among the interneurons, which account for most of its constituent neurons. All primary afferents, and the great majority of neurons in laminae I-III are glutamatergic, and a major factor limiting our understanding of the synaptic circuitry has been the difficulty in identifying glutamatergic synapses with light microscopy. Although there are numerous potential targets for antibodies, these are difficult to visualize with immunocytochemistry, because of protein cross-linking following tissue fixation. Although this can be overcome by antigen retrieval methods, these lead to difficulty in detecting other antigens. The aim of this study was to test whether the postsynaptic protein Homer can be used to reveal glutamatergic synapses in the dorsal horn. Immunostaining for Homer gave punctate labeling when viewed by confocal microscopy, and this was restricted to synapses at the ultrastructural level. We found that Homer puncta were colocalized with the AMPA receptor GluR2 subunit, but not with the inhibitory synapse-associated protein gephyrin. We also examined several populations of glutamatergic axons and found that most boutons were in contact with at least one Homer punctum. These results suggest that Homer antibodies can be used to reveal the great majority of glutamatergic synapses without antigen retrieval. This will be of considerable value in tracing synaptic circuits, and also in investigating plasticity of glutamatergic synapses in pain states. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. [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.

  2. Spinal estrogen attenuates the exercise pressor reflex but has little effect on the expression of genes regulating neurotransmitters in the dorsal root ganglia.

    PubMed

    Schmitt, Petra M; Gohil, Kishorchandra; Kaufman, Marc P

    2006-03-01

    Previously, our laboratory showed that estrogen, topically applied to the spinal cord, attenuated the exercise pressor reflex in female cats (Schmitt PM and Kaufman MP. J Appl Physiol 95: 1418-1424, 2003; 98: 633-639, 2005). The attenuation was gender specific and was in part opioid dependent. Our finding that the mu- and delta-opioid antagonist naloxone was only able to partially restore estrogen's attenuating effect on the pressor response to static contraction suggested that estrogen affected an additional pathway, involving the dorsal root ganglion (DRG). Estrogen has been described to stimulate transcription within 10 min of its application to the DRG, raising the possibility that rapid genomic effects on neurotransmitter production may have contributed to estrogen's effect on the exercise pressor reflex. This prompted us to test the hypothesis that estrogen modulated the pressor response to static contraction by influencing gene expression of the neurotransmitters released by the thin-fiber muscle afferents that evoke the exercise pressor reflex. We confirmed in decerebrated female rats that topical application of estrogen (0.01 microg/ml) to the lumbosacral spinal cord attenuated the pressor response to static muscle contraction (from 10+/-3 to 1+/-1 mmHg; P<0.05). DRG were then harvested postmortem, and changes in mRNA expression were analyzed. GeneChip analysis revealed that neither estrogen nor contraction alone changed the mRNA expression of substance P, the neurokinin-1 receptor, CGRP, NGF, the P2X3 receptor, GABAA and GABAB, the 5-HT3A and 5-HT3B receptor, N-methyl-D-aspartate and non-N-methyl-D-aspartate receptors, opioid receptors, and opioid-like receptor. Surprisingly, however, contraction stimulated the expression of neuropeptide Y in the DRG in the presence and absence of estrogen. We conclude that estrogen does not attenuate the exercise pressor reflex through a genomic effect in the DRG.

  3. Peripheral oxytocin receptors inhibit the nociceptive input signal to spinal dorsal horn wide-dynamic-range neurons.

    PubMed

    González-Hernández, Abimael; Manzano-García, Alfredo; Martínez-Lorenzana, Guadalupe; Tello-García, Irma A; Carranza, Martha; Arámburo, Carlos; Condés-Lara, Miguel

    2017-07-19

    Oxytocin (OT) has emerged as a mediator of endogenous analgesia in behavioral and electrophysiological experiments. In fact, OT receptors (OTRs) in the spinal dorsal horn participate in a selective inhibition of the neuronal activity mediated by Aδ and C fibers but not Aβ fibers. This study shows that OTRs are expressed in the terminal nerve endings and are able to inhibit nociceptive neuronal firing. Indeed, local peripheral OT blocked the first sensorial activity of Aδ and C fibers recorded in the spinal cord neurons. Furthermore, using the formalin behavioral nociceptive test, we demonstrated that only ipsilateral OTR activation inhibits pain behavior. Our data are reinforced by the fact that the OTR protein is expressed in the sciatic nerve. Consistent with this, immunofluorescence of primary afferent fibers suggest that OTRs could be located in nociceptive-specific terminals of the skin. Taken together, our results suggest that OTRs could be found in nociceptive terminals and that on activation they are able to inhibit nociceptive input.

  4. [Establishment of tractive spinal cord injury model in rats with a novel spinal distractor].

    PubMed

    Wang, Wenyue; Yang, Tianfu; Lei, Mingming; Pei, Fuxing; Liu, Lei

    2011-06-01

    To develop a tractive spinal cord injury model in rats with a novel spinal distractor so as to supply the reliable animal model for researching the pathological mechanism and rehabilitation treatment of tractive spinal cord injury. A novel spinal distractor was prepared based on previous study. Sixty adult Sprague Dawley rats (weighing 250-300 g) were randomly divided into 5 groups, 12 rats in each group. T12-L3 spinal structures in the rear area were exposed and then T13-L2 spinal cords were revealed via dual laminectomy and kept integrity. In group A, a novel spinal distractor was placed without distraction; in groups B, C, D, and E, the T12-L3 spines were traced with a novel spinal distractor which put on transverse process of T12-L3 vertebrae. During the tractive period, the somatosensory evoked potential (SEP) was used to monitor spinal cord function. The SEP amplitudes descended 50% and kept distracting for 5 minutes in group B and for 10 minutes in group C, and descended 70% and kept distracting for 5 minutes in group D and for 10 minutes in group E, respectively to establish the tractive spinal cord injury model of T11-L2. The improved combine behavioral score (ICBS) was recorded at 1 and 7 days after injury in 6 rats of each group. The T13-L2 spinal tissue specimens were harvested for the morphological observation by HE and Nissl's staining and for neurons counting. In group A, the ICBS score was 0 at 1 and 7 days after operation, showing significant difference when compared with the scores of the other groups (P < 0.05). The ICBS scores of groups D and E were significantly higher than those of groups B and C (P < 0.05). Edema and hemorrhage were observed in spinal cord surface and normal morphological structures were destroyed at different extent in groups B, C, D, and E at 1 day. There were adherence and congestion between spinal cord surface and peripheral issue without luster at 7 days, and dura depression was observed at the injury section, especially

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. Sub-threshold spinal cord stimulation facilitates spontaneous motor activity in spinal rats

    PubMed Central

    2013-01-01

    Background Epidural stimulation of the spinal cord can be used to enable stepping on a treadmill (electrical enabling motor control, eEmc) after a complete mid-thoracic spinal cord transection in adult rats. Herein we have studied the effects of eEmc using a sub-threshold intensity of stimulation combined with spontaneous load-bearing proprioception to facilitate hindlimb stepping and standing during daily cage activity in paralyzed rats. Methods We hypothesized that eEmc combined with spontaneous cage activity would greatly increase the frequency and level of activation of the locomotor circuits in paralyzed rats. Spontaneous cage activity was recorded using a specially designed swivel connector to record EMG signals and an IR based camcorder to record video. Results and conclusion The spinal rats initially were very lethargic in their cages showing little movement. Without eEmc, the rats remained rather inactive with the torso rarely being elevated from the cage floor. When the rats used their forelimbs to move, the hindlimbs were extended and dragged behind with little or no flexion. In contrast, with eEmc the rats were highly active and the hindlimbs showed robust alternating flexion and extension resulting in step-like movements during forelimb-facilitated locomotion and often would stand using the sides of the cages as support. The mean and summed integrated EMG levels in both a hindlimb flexor and extensor muscle were higher with than without eEmc. These data suggest that eEmc, in combination with the associated proprioceptive input, can modulate the spinal networks to significantly amplify the amount and robustness of spontaneous motor activity in paralyzed rats. PMID:24156340

  15. 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

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

    PubMed

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

    2016-03-01

    Volatile anesthetics decrease Ca²⁺ entry through voltage-dependent Ca²⁺ channels. Ca 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. 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. 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. 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 is sufficient or whether actions on other channels/proteins contribute to isoflurane-induced immobility.

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

    PubMed Central

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

    2011-01-01

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

  18. 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.

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

    PubMed Central

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

    2013-01-01

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

  20. 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

  1. 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.

  2. 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.

  3. Repeated topical application of growth hormone attenuates blood-spinal cord barrier permeability and edema formation following spinal cord injury: an experimental study in the rat using Evans blue, ([125])I-sodium and lanthanum tracers.

    PubMed

    Nyberg, F; Sharma, H S

    2002-01-01

    The neuroprotective efficacy of growth hormone on a focal spinal cord trauma induced alteration in the blood-spinal cord barrier (BSCB) and edema formation was examined in a rat model. Under Equithesin anaesthesia, one segment laminectomy was done over the T10-11 segments. Spinal cord injury was produced by making an incision into the right dorsal horn of the T10-11 segments (2 mm deep and 4 mm long). The animals were allowed to survive 5 h after injury. Highly purified rat growth hormone [rGH, 25 microl of a 1microg/ml solution) was applied over 10 sec topically on the exposed surface of the spinal cord 30 min before injury. The identical doses of the rGH were repeated 0 min, 30 min, 60 min, 120 min, 180 min and 240 min following injury. Saline (0.9% NaCl) treated traumatised rats at identical intervals served as controls. Traumatised rats treated with saline exhibited marked edema formation and extravasation of Evans blue and ([125])Iodine tracers in the spinal cord. At the ultrastructural level, perivascular edema and exudation of lanthanum across the endothelial cells was quite frequent in the spinal cord. Pretreatment with rGH significantly attenuated the edema formation and the extravasation of tracers in the spinal cord. In these rats, perivascular edema and infiltration of lanthanum across the endothelial cells was not much evident. These observations show that the rGH has the capacity to reduce the early manifestations of microvascular permeability disturbances and edema formation following trauma and further suggest a possible therapeutic potential of the hormone for the treatment of spinal cord injuries.

  4. 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.

  5. ANTI-CD11d MONOCLONAL ANTIBODY TREATMENT FOR RAT SPINAL CORD COMPRESSION INJURY

    PubMed Central

    Hurtado, Andres; Marcillo, Alexander; Frydel, Beata; Bunge, Mary Bartlett; Bramlett, Helen M.; Dietrich, W. Dalton

    2010-01-01

    This study was initiated due to an NIH “Facilities of Research - Spinal Cord Injury” contract to support independent replication of published studies. Transient blockage of the CD11d/CD18 integrin has been reported to reduce secondary neuronal damage as well as to improve functional recovery after spinal cord injury (SCI) in rats. The purpose of this study was to determine whether treatment with an anti-CD11d monoclonal antibody (mAb) would improve motor performance, reduce pain and histopathological damage in animals following clip-compression injury as reported. Adult male Wistar rats (250 g) were anesthetized with isoflurane, and the T12 spinal cord exposed by T10 and T11 dorsal laminectomies followed by a 60 second period of clip compression utilizing a 35 gram clip. Control animals received an isotype-matched irrelevant antibody (1B7) while the treated group received the anti-CD11d mAb (217L; 1.0 mg/kg) systemically. Open-field locomotion and sensory function were assessed and animals were perfusion-fixed at twelve weeks after injury for quantitative histopathological analysis. As compared to 1B7, 217L treated animals showed an overall non-significant trend to better motor recovery. All animals showed chronic mechanical allodynia and anti-CD11d mAb treatment did not significantly prevent its development. Histopathological analysis demonstrated severe injury to gray and white matter after compression with a non-significant trend in anti-CD11d protection compared to control animals for preserved myelin. Although positive effects with the anti-CD11d mAb treatment have been reported after compressive SCI, it is suggested that this potential treatment requires further investigation before clinical trials in spinal cord injured patients are implemented. PMID:21145887

  6. Anti-CD11d monoclonal antibody treatment for rat spinal cord compression injury.

    PubMed

    Hurtado, Andres; Marcillo, Alexander; Frydel, Beata; Bunge, Mary Bartlett; Bramlett, Helen M; Dietrich, W Dalton

    2012-02-01

    This study was initiated due to an NIH "Facilities of Research-Spinal Cord Injury" contract to support independent replication of published studies. Transient blockage of the CD11d/CD18 integrin has been reported to reduce secondary neuronal damage as well as to improve functional recovery after spinal cord injury (SCI) in rats. The purpose of this study was to determine whether treatment with an anti-CD11d monoclonal antibody (mAb) would improve motor performance, reduce pain and histopathological damage in animals following clip-compression injury as reported. Adult male Wistar rats (250g) were anesthetized with isoflurane, and the T12 spinal cord exposed by T10 and T11 dorsal laminectomies followed by a 60s period of clip compression utilizing a 35g clip. Control animals received an isotype-matched irrelevant antibody (1B7) while the treated group received the anti-CD11d mAb (217L; 1.0mg/kg) systemically. Open-field locomotion and sensory function were assessed and animals were perfusion-fixed at twelve weeks after injury for quantitative histopathological analysis. As compared to 1B7, 217L treated animals showed an overall non-significant trend to better motor recovery. All animals showed chronic mechanical allodynia and anti-CD11d mAb treatment did not significantly prevent its development. Histopathological analysis demonstrated severe injury to gray and white matter after compression with a non-significant trend in anti-CD11d protection compared to control animals for preserved myelin. Although positive effects with the anti-CD11d mAb treatment have been reported after compressive SCI, it is suggested that this potential treatment requires further investigation before clinical trials in spinal cord injured patients are implemented. Copyright © 2010 Elsevier Inc. All rights reserved.

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. Development of a Rat Model of Graded Contusive Spinal Cord Injury Using a Pneumatic Impact Device

    PubMed Central

    Yeo, Sang Jun; Park, Seung Won; Kim, Young Baeg; Min, Byung Kook; Kwon, Jeong Taik; Suk, Jong Sik

    2004-01-01

    An animal model of spinal cord trauma is essential for understanding the injury mechanisms, cord regeneration, and to aid the development of new therapeutic modalities. This study focused on the development of a graded experimental contusion model for spinal cord injury (SCI) using a pneumatic impact device made in Korea. A contusive injury was made to the dorsal aspect of the cord. Three trauma groups were defined according to the impact velocity (IV). A control group (n=6), received laminectomy only. Group 1 (n=10), 2 (n=10), and 3 (n=10) had IVs of 1.5 m/sec, 2.0 m/sec, and 3.5 m/sec respectively. Functional assessments were made up to the 14th day after injury. The cord was removed at the 14th post-injury day and prepared for histopathologic examination. Significant behavioral and histopathological abnormalities were found in control and each trauma group. All trauma groups showed severe functional impairment immediately after injury but following different rates of functional recovery (Fig. 5). As the impact velocity and impulse increased, the depth of contusive lesion revealed to be profound the results show that the rat model reproduces spinal cord lesions consistently, has a distinctive value in assessing the effects of impact energy. PMID:15308850

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. Effects of sacral neuromodulation on isolated urinary bladder function in a rat model of spinal cord injury.

    PubMed

    Kumsar, Şükrü; Keskin, Ulya; Akay, Alaaddin; Bilgilisoy, Uğur Taylan; Erdem, Ş Remzi; Peşkircioğlu, Ç Levent; Özkardeş, Hakan

    2015-01-01

    Sacral neuromodulation has been considered as an effective treatment option for various types of chronic voiding dysfunction, but the mechanism of action has not been well understood. The aim of this study was to evaluate the effect of chronic sacral neuromodulation on isolated bladder functions in a rat model of spinal cord injury. Female Sprague-Dawley rats (250-300 g; N = 20) were assigned to four groups as follows: 1) control group (N = 6); 2) spinal cord transection group (SCT; N = 5); 3) spinal cord transection + sacral neuromodulation group (SCT + SNM; N = 5); 4) sham (spinal cord transection + electrode wire implantation without sacral neuromodulation; N = 4). The rats in the SCT, SCT + SNM, and sham groups were anesthetized with ketamine (60 mg/kg, i.p.) and xylazine (7 mg/kg, i.p.). The spinal cord was completely transected at T8-T9 level in SCT and SCT + SNM groups. Electrode wires were implanted into S3 dorsal foramina in both sham and SNM groups, but only the SNM group was subjected to electrical stimulation for four hours a day for three weeks. Twenty-one days later, the rats were sacrificed via anesthetic overdose, and isolated longitudinal bladder strip preparations were placed in organ baths for the investigation of their isometric responses to pharmacological agents. In isometric contraction experiments, SCT was found to increase the contraction responses of the bladder strips to muscarinic stimulation, and SNM could not prevent this increase. In isometric relaxation experiments, SCT caused a decrease in β-adrenergic relaxation responses, and SNM augmented the bladder's β-adrenergic relaxation responses. Nitric oxide did not affect the relaxation responses. In our rat model of SCT, SNM seemed to alter adrenergic receptor function in the urinary bladder. Further studies are required to clarify the mechanism of these alterations at the level of bladder receptors following sacral neuromodulation. © 2014 International Neuromodulation Society.

  2. 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. © 2015 Wiley Periodicals, Inc.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. 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

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

    PubMed

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

    2016-01-01

    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. 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. 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. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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

  17. 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.

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

    PubMed Central

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

    2014-01-01

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

  19. Teratogenic Effects of Pyridoxine on the Spinal Cord and Dorsal Root Ganglia of Embryonic Chickens

    PubMed Central

    Sharp, Andrew A.; Fedorovich, Yuri

    2015-01-01

    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, DRG and peripheral nerves, we find that pyridoxine causes a loss of TrkC-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 CGRP-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 asses how the loss of sensation, largely proprioception, alters spontaneous embryonic motility and subsequent motor development. PMID:25592428

  20. 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

  1. Activation of Mu or Delta Opioid Receptors in the Lumbosacral Spinal Cord Is Essential for Ejaculatory Reflexes in Male Rats

    PubMed Central

    Kozyrev, Natalie; Coolen, Lique M.

    2015-01-01

    Ejaculation is controlled by a spinal ejaculation generator located in the lumbosacral spinal cord, consisting in male rats of lumbar spinothalamic (LSt) cells and their inter-spinal projections to autonomic and motor centers. LSt cells co-express several neuropeptides, including gastrin releasing peptide (GRP) and enkephalin. We previously demonstrated in rats that GRP regulates ejaculation by acting within the lumbosacral spinal cord. In the present study, the hypothesis was tested that enkephalin controls ejaculation by acting on mu (MOR) or delta opioid receptors (DOR) in LSt target areas. Adult male rats were anesthetized and spinalized and received intrathecal infusions of vehicle, MOR antagonist CTOP (0.4 or 4 nmol), DOR antagonist (TIPP (0.4, 4 or 40 nmol), MOR agonist DAMGO (0.1 or 10 nmol), or DOR agonist deltorphin II (1.3 or 13 nmol). Ejaculatory reflexes were triggered by stimulation of the dorsal penile nerve (DPN) and seminal vesicle pressure and rhythmic contractions of the bulbocavernosus muscle were analyzed. Intrathecal infusion of MOR or DOR antagonists effectively blocked ejaculatory reflexes induced by DPN stimulation. Intrathecal infusion of DAMGO, but not deltorphin II triggered ejaculation in absence of DPN stimulation. Both MOR and DOR agonists facilitated ejaculatory reflexes induced by subthreshold DPN stimulation in all animals. Overall, these results support the hypothesis that enkephalin plays a critical role in the control of ejaculation in male rats. Activation of either MOR or DOR in LSt target areas is required for ejaculation, while MOR activation is sufficient to trigger ejaculation in the absence of sensory stimulation. PMID:25826331

  2. Blockade of NMDA receptors decreased spinal microglia activation in bee venom induced acute inflammatory pain in rats.

    PubMed

    Li, Li; Wu, Yongfang; Bai, Zhifeng; Hu, Yuyan; Li, Wenbin

    2017-03-01

    Microglial cells in spinal dorsal horn can be activated by nociceptive stimuli and the activated microglial cells release various cytokines enhancing the nociceptive transmission. However, the mechanisms underlying the activation of spinal microglia during nociceptive stimuli have not been well understood. In order to define the role of NMDA receptors in the activation of spinal microglia during nociceptive stimuli, the present study was undertaken to investigate the effect of blockade of NMDA receptors on the spinal microglial activation induced by acute peripheral inflammatory pain in rats. The acute inflammatory pain was induced by subcutaneous bee venom injection to the plantar surface of hind paw of rats. Spontaneous pain behavior, thermal withdrawal latency and mechanical withdrawal threshold were rated. The expression of specific microglia marker CD11b/c was assayed by immunohistochemistry and western blot. After bee venom treatment, it was found that rats produced a monophasic nociception characterized by constantly lifting and licking the injected hind paws, decreased thermal withdrawal latency and mechanical withdrawal threshold; immunohistochemistry displayed microglia with enlarged cell bodies, thickened, extended cellular processes with few ramifications, small spines, and intensive immunostaining; western blot showed upregulated expression level of CD11b/c within the period of hyperalgesia. Prior intrathecal injection of MK-801, a selective antagonist of NMDA receptors, attenuated the pain behaviors and suppressed up-regulation of CD11b/c induced by bee venom. It can be concluded that NMDA receptors take part in the mediation of spinal microglia activation in bee venom induced peripheral inflammatory pain and hyperalgesia in rats.

  3. 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.

  4. 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

  5. Predominant role of spinal P2Y1 receptors in the development of neuropathic pain in rats

    PubMed Central

    Barragán-Iglesias, Paulino; Pineda-Farias, Jorge Baruch; Bravo-Hernández, Mariana; Cervantes-Durán, Claudia; Price, Theodore J.; Murbartián, Janet; Granados-Soto, Vinicio

    2016-01-01

    The role of P2X2/3, P2X3, P2X4 or P2X7 and P2Y2, P2Y6, and P2Y12 receptors in neuropathic pain has been widely studied. In contrast, the role of P2Y1 receptors is scarcely studied. In this study we assessed the role of P2Y1 receptors in several neuropathic pain models in the rat. Furthermore, we analyzed the expression of P2Y1 receptors in the ipsilateral dorsal root ganglia (DRG) and dorsal part of the spinal cord during the development and maintenance of neuropathic pain. We also determined the effect of the P2Y1 receptor antagonist on the expression of P2Y1 receptors. Spinal nerve ligation (SNL), chronic constriction injury (CCI) or spared nerve injury (SNI) produced tactile allodynia from 1 to 14 days after nerve injury. SNL, CCI and SNI enhanced expression of P2Y1 receptors in DRG but not in the dorsal part of the spinal cord at 1-3 days after injury. Intrathecal injection of the selective P2Y1 receptor antagonist MRS2500, but not vehicle, reduced tactile allodynia in rats 1-3 days after SNL, CCI or SNI. Moreover, intrathecal injection of MRS2500 (at day 1 or 3) reduced neuropathy-induced up-regulation of P2Y1 receptors expression. Intrathecal injection of MRS2500 lost most of the antiallodynic effect when injected 14 days after injury. Our results suggest that P2Y1 receptors are localized in DRG, are up-regulated by nerve injury and play a pronociceptive role in development and, to a lesser extent, maintenance of neuropathic pain. PMID:26835558

  6. 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.

  7. Spatiotemporal patterns of Gem expression after rat spinal cord injury.

    PubMed

    Wen, Hai; Cao, Jianhua; Yu, Xiaowei; Sun, Binbin; Ding, Tao; Li, Ming; Li, Debao; Wu, Hao; Long, Long; Xu, Guangfei; Zhang, Feng

    2013-06-21

    Gem is an atypical protein of the Ras superfamily that plays a role in regulating voltage-gated Ca(2+) channels and cytoskeletal reorganization. To elucidate the certain expression and biological function in central nervous system (CNS), we performed an acute spinal cord contusion injury model in adult rats. Western blot analysis showed a marked up-regulation of Gem after spinal cord injury (SCI). Immunohistochemistry revealed wide distribution of Gem in spinal cord, including neurons and glial cells. Double immunofluorescent staining for proliferating cell nuclear antigen (PCNA) and phenotype-specific markers indicated increases of Gem expression in proliferating microglia and astrocytes. Our data suggest that Gem may be implicated in the proliferation of microglia and astrocytes after SCI. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. Immunocytochemical localisation of microtubule-associated proteins 1b and 2 in the developing rat spinal cord.

    PubMed Central

    Oudega, M; Touri, F; Deenen, M G; Riederer, B M; Marani, E

    1995-01-01

    The straightforward anatomical organisation of the developing and mature rat spinal cord was used to determine and interpret the time of appearance and expression patterns of microtubule-associated proteins (MAP) 1b and 2. Immunoblots revealed the presence of MAP1b and 2 in the early embryonic rat spinal cord and confirmed the specificity of the used anti-MAP mouse monoclonal antibodies. The immunocytochemical data demonstrated a rostral-to-caudal and ventral-to-dorsal gradient in the expression of MAP1b/2 within the developing spinal cord. In the matrix layer, MAP1b was found in a distinct radial pattern distributed between the membrana limitans interna and externa between embryonal day (E)12 and E15. Immunostaining for vimentin revealed that this MAP1b pattern was morphologically and topographically different from the radial glial pattern which was present in the matrix layer between E13 and E19. The ventral-to-dorsal developmental gradient of the MAP1b staining in the spinal cord matrix layer indicates a close involvement of MAP1b either in the organisation of the microtubules in the cytoplasmatic extensions of the proliferating neuroblasts or neuroblast mitosis. MAP2 could not be detected in the developing matrix layer. In the mantle and marginal layer, MAP1b was abundantly present between E12 and postnatal day (P)0. After birth, the staining intensity for MAP1b gradually decreased in both layers towards a faint appearance at maturity. The distribution patterns suggest an involvement of MAP1b in the maturation of the motor neurons, the contralaterally and ipsilaterally projecting axons and the ascending and descending long axons of the rat spinal cord. MAP2 was present in the spinal cord grey matter between E12 and maturity, which reflects a role for MAP2 in the development as well as in the maintenance of microtubules. The present description of