Proposed novel unified nomenclature for range of joint motion: method for measuring and recording for the ankles, feet, and toes.

The Ad Hoc Committee of Terminology of the Japanese Society for Surgery of the Foot (JSSF) proposes novel terminology for motion of the ankle, foot, and toe because there are some ambiguities in the current terminology. Articles were identified by searching the electronic databases of PubMed that compared definitions of American Orthopaedic Foot and Ankle Society (AOFAS), International Society of Biomechanics (ISB), and in the textbook of Kapandji as well as the American Academy of Orthopaedic Surgeons (AAOS). A total of 11 articles described the transverse (horizontal) plane motion in the hindfoot as external rotation/internal rotation and 10 as abduction/adduction. In all, 2 articles described the transverse (horizontal) plane motion in midfoot as external rotation/internal rotation and 10 as abduction/adduction. Another 4 articles described the transverse (horizontal) plane motion in the forefoot as external rotation/internal rotation and 8 as abduction/adduction. Altogether, 109 articles described the sagittal plane motion of the foot/ankle as dorsiflexion/plantarflexion and 20 as extension/flexion. In all, 99 articles described the frontal (coronal) plane motion of the foot/ankle as inversion/eversion and 4 as supination/pronation. Furthermore, 12 articles described the sagittal plane motion of toes as dorsiflexion/plantarflexion and 15 as extension/flexion. Another 16 articles described the frontal (coronal) plane motion of toes as supination/pronation and 1 as inversion/eversion. The transverse (horizontal) plane motion of the foot/ankle was defined as abduction/adduction in the hindfoot, midfoot, and forefoot; the sagittal plane motion of the foot/ankle was defined as dorsiflexion/plantarflexion; and the frontal (coronal) plane motion of the foot/ankle as inversion/eversion. The transverse (horizontal) plane motion of toes was defined as abduction/adduction; the sagittal plane motion of toes was defined as extension/flexion; and the frontal (coronal) plane motion of toes was defined as supination/pronation.

The p75 receptor is associated with inflammatory thermal hypersensitivity.

Inflammatory pain, characterized by a decrease in the nociceptive threshold, arises through the actions of inflammatory mediators, and one of the key molecules is nerve growth factor (NGF). Here we report that the administration of neutralizing antibody to the neurotrophin receptor p75 (p75(NTR)) blocks hyperalgesia, which develops with complete Freund's adjuvant (CFA)-induced inflammation or with an intraplantar injection of NGF. Although CFA injection results in the up-regulation of calcitonin gene-related peptide (CGRP) levels in the primary sensory neurons, blocking p75(NTR) abolishes this effect. We further demonstrate that pro-NGF is the predominant ligand of p75(NTR) in vivo. Plasmin treatment, which is intended to decompose pro-NGF, ameliorates CFA-induced hyperalgesia. In addition, an intraplantar injection of pro-NGF induces hyperalgesia. These data together suggest that pro-NGF, as well as mature NGF, binding to p75(NTR) plays an important role in inflammation-induced hyperalgesia. Interference in the binding may provide a therapeutic approach for the treatment of inflammatory pain.

Sensory innervation of lumbar vertebral bodies in rats.

STUDY DESIGN: Using a retrograde neurotracing method with Fluoro-Gold (FG), the level at which dorsal root ganglions (DRGs) innervate the L2 and L5 vertebral bodies and the innervation pathways were investigated in rats. OBJECTIVE: To clarify the levels at which DRGs innervate the lumbar vertebral bodies and to determine the pathways from the L2 and L5 vertebral bodies to DRGs. SUMMARY OF BACKGROUND DATA: Elderly patients with osteoporosis sometimes experience lumbar vertebral fracture and may also feel diffuse nonlocalized pain in the back, lateral portion of the trunk, and area surrounding the iliac crest. However, the pattern of sensory innervation of vertebral bodies remains unclear. METHODS: Forty female Sprague-Dawley rats were used. FG crystals were applied to the L2 (L2 vertebra group) or L5 (L5 vertebra group) vertebral bodies via an anterior approach, and numbers of labeled neurons in DRGs from T10 to L6 were counted. To determine sensory pathways, bilateral sympathectomy was performed. RESULTS: In nonsympathectomy animals, FG-labeled neurons were present in DRGs from T11 through L3 in the L2 vertebra group and from T13 through L6 in the L5 vertebra group. The number of labeled neurons following sympathectomy was not significantly different in L1, L2, and L3 DRGs in the L2 vertebra group or in L3, L4, L5, and L6 DRGs in the L5 vertebra group from those in nonsympathectomy animals. In contrast, fewer labeled DRG neurons were present in sympathectomy animals at T11, T12, and T13 in the L2 vertebra group, and at T13, L1, and L2 in the L5 vertebra group than in nonsympathectomy animals (P < 0.01). CONCLUSION: Sensory nerve fibers in the L2 and L5 vertebral bodies are derived from the T11-L3 and T13-L6 DRGs, respectively. Some sensory nerves from the L2 and L5 vertebral bodies enter the paravertebral sympathetic trunks and reach the DRGs at multisegmental levels. The present findings regarding multisegmental innervation to vertebral bodies may explain the diffuse pain that originates within osteoporotic vertebral fractures in elderly patients.

Up-regulation of p55 TNF alpha-receptor in dorsal root ganglia neurons following lumbar facet joint injury in rats.

The rat L5/6 facet joint is multisegmentally innervated from the L1 to L6 dorsal root ganglia (DRG). Tumor necrosis factor (TNF) is a known mediator of inflammation. It has been reported that satellite cells are activated, produce TNF and surround DRG neurons innervating L5/6 facet joints after facet injury. In the current study, changes in TNF receptor (p55) expression in DRG neurons innervating the L5/6 facet joint following facet joint injury were investigated in rats using a retrograde neurotransport method followed by immunohistochemistry. Twenty rats were used for this study. Two crystals of Fluorogold (FG; neurotracer) were applied into the L5/6 facet joint. Seven days after surgery, the dorsal portion of the capsule was cut in the injured group (injured group n = 10). No injury was performed in the non-injured group (n = 10). Fourteen days after the first application of FG, bilateral DRGs from T13 to L6 levels were resected and sectioned. They were subsequently processed for p55 immunohistochemistry. The number of FG labeled neurons and number of FG labeled p55-immunoreactive (IR) neurons were counted. FG labeled DRG neurons innervating the L5/6 facet joint were distributed from ipsilateral L1 to L6 levels. Of FG labeled neurons, the ratio of DRG neurons immunoreactive for p55 in the injured group (50%) was significantly higher than that in the non-injured group (13%). The ratio of p55-IR neurons of FG labeled DRG neurons was significantly higher in total L1 and L2 DRGs than that in total L3, 4, 5 and 6 DRGs in the injured group (L1 and 2 DRG, 67%; L3, 4, 5 and 6 DRG, 37%, percentages of the total number of p55-IR neurons at L1 and L2 level or L3-6 level/the total number of FG-labeled neurons at L1 and L2 level or L3-6 level). These data suggest that up-regulation of p55 in DRG neurons may be involved in the sensory transmission from facet joint injury. Regulation of p55 in DRG neurons innervating the facet joint was different between upper DRG innervated via the paravertebral sympathetic trunks and lower DRG innervated via other direct routes.

Characteristics of sensory dorsal root ganglia neurons innervating the lumbar vertebral body in rats.

UNLABELLED: Characteristics of sensory dorsal root ganglia (DRG) neurons innervating the L5 vertebral body were investigated in rats by using a retrograde neurotransport method, lectin affinity- and immuno-histochemistry to further elucidate the causes of diffuse pain suffered by some elderly patients in their back, lateral trunk, and iliac crest, after lumbar osteoporotic vertebral fracture. We used calcitonin gene-related peptide (CGRP) as a marker of small peptide-containing neurons and the glycoprotein binding the isolectin from Griffonia simplicifolia (IB4) as a marker of small non-peptide-containing neurons. Neurons innervating the L5 vertebral bodies, retrogradely labeled with fluoro-gold (FG), were distributed throughout DRGs from T13 to L6. The proportion of CGRP-immunoreactive (IR) FG-labeled neurons was 32%. The proportion of IB4-binding FG-labeled neurons was significantly smaller, at 4%. Other neurons that were non-CGRP-IR and non-IB4-binding were mostly large neurons, and they may transmit proprioception from vertebral bodies. Most neurons transmitting pain are CGRP-IR peptide-containing neurons. They may have a more significant role in pain sensation in the vertebral bodies as peptidergic DRG neurons. PERSPECTIVE: This article shows that vertebral bodies are innervated by CGRP-IR neurons. CGRP-IR neurons may play a role in pain sensation through peptidergic DRG neurons. These findings contribute to an understanding of pain associated with the vertebral body such as tumor, infection, or osteoporotic fracture.

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

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.

Glial phosphorylated p38 MAP kinase mediates pain in a rat model of lumbar disc herniation and induces motor dysfunction in a rat model of lumbar spinal canal stenosis.

STUDY DESIGN: Immunohistochemical and behavioral study using rat models of lumbar disc herniation and cauda equina syndrome. OBJECTIVE: To investigate the expression of activated p38 mitogen-activated protein kinases (p38 MAP kinase; p38) in the spinal cord and to determine the effect of intrathecal administration of a specific p38 inhibitor on pain in a lumbar disc herniation model and on motor function and hypoalgesia in a spinal canal stenosis (SCS) model. SUMMARY OF BACKGROUND DATA: In pathologic lumbar disc herniation-induced neuropathic pain and compression of cauda equina-induced motor dysfunction and hypoalgesia caused by SCS, glia are activated and produce certain cytokines, including tumor necrosis factor-alpha (TNF-alpha) and interleukins, which play a crucial role in the pathogenesis of nerve degeneration. p38 is phosphorylated by these cytokines, suggesting that it may play an important role in pain transmission and nerve degeneration. Here we have examined the role of p38 in rat models of lumbar disc herniation and SCS. METHODS: Six-week-old male Sprague-Dawley rats were used. For the disc herniation model, autologous nucleus pulposus was applied to L5 nerve roots, which were then crushed. For the SCS model, a piece of silicon was placed under the lamina of the fourth lumbar vertebra. We assessed mechanical allodynia, hypoalgesia, and motor function using von Frey hairs, treadmill tests, and immunohistochemical localization of phosphorylated p38 (P-p38) in the cauda equina, dorsal root ganglion (DRG), and spinal cord, which were also double-stained with NeuN (neuronal marker), GFAP (astrocyte/Schwann cell marker), or isolectin B4 (IB4; microglia marker). We also examined the effects of intrathecal administration of a specific p38 inhibitor, FR167653, on nucleus pulposus-induced pain, hypoalgesia, and motor dysfunction following SCS. RESULTS: We demonstrated that activated P-p38-immunoreactive cells in the spinal cord and cauda equina were not observed before nerve injury but appeared in the cauda equina, DRG, and spinal dorsal horn in the disc herniation and SCS models. Double-labeling revealed that most P-p38-immunoreactive cells were isolectin B4-labeled microglia and GFAP-immunoreactive Schwann cells. Intrathecal administration of the p38 inhibitor FR167653 decreased mechanical allodynia in the disc herniation model and improved hypoalgesia and intermittent motor dysfunction in the SCS model. CONCLUSIONS: Our findings suggest that activated p38 may play an important role in the involvement of microglia in the pathophysiology of pain following lumbar disc herniation and mechanical hypoalgesia, and motor nerve dysfunction of cauda equina following SCS.

Substance P-saporin down-regulates substance P receptor immunoreactive sensory dorsal root ganglion neurons innervating the lumbar intervertebral discs in rats.

STUDY DESIGN: To examine changes in substance P receptors on dorsal root ganglion cells innervating the rat lumbar intervertebral discs using immunohistochemistry and a retrograde neurotracing method. OBJECTIVE: We evaluated the effects of intradiscal administration of substance P-saporin, a toxin selective for cells expressing substance P receptors. SUMMARY OF BACKGROUND DATA: The rat L5/6 intervertebral disc is multi-segmentally innervated from the L1-L6 dorsal root ganglions. Substance P and the neurokinin-1 receptor contribute to inflammatory pain transmission. Substance P immunoreactive-sensory nerve fibers in human intervertebral discs and immunoreactive-dorsal root ganglion neurons innervating rat intervertebral discs have been reported to be important in the transmission of discogenic low back pain. In the current study, we evaluated the effects of intradiscal administration of substance P-saporin, a toxin selective for cells expressing substance P receptor. METHODS: Sixteen rats were used (control group, n = 8; substance P-saporin group, n = 8). To detect dorsal root ganglion neurons innervating the L5/6 intervertebral disc, neurotracer (fluoro-gold crystals) was placed into the intervertebral disc. Seven days after fluoro-gold application, the L5/6 intervertebral disc was exposed and injected with 175 ng of sterile substance P-saporin (substance P-saporin group, n = 8). Fourteen days after the first operation, each dorsal root ganglion was harvested, sectioned, and processed for neurokinin-1 immunohistochemistry using rabbit antibody to neurokinin-1. The numbers of fluoro-gold labeled neurons, and fluoro-gold labeled and neurokinin-1 immunoreactive neurons were counted in both groups. RESULTS: Neurons innervating the L5/6 intervertebral discs, retrogradely labeled with fluoro-gold, were distributed throughout dorsal root ganglions from L1 to L6 in both groups. Of fluoro-gold labeled neurons, the proportion of neurokinin-1 immunoreactive neurons was 35% in the control group. However, the proportion of neurokinin-1 immunoreactive neurons was 8% after administration of substance P-saporin into the intervertebral discs (substance P-saporin group). Substance P-saporin significantly decreased the ratio of neurokinin-1 immunoreactive neurons. CONCLUSION: Substance P-saporin decreased the ratio of neurokinin-1 immunoreactive neurons innervating the disc related to discogenic low back pain. Substance P-saporin may be a useful tool to investigate the mechanism of discogenic low back pain.

Injection of nuclear factor-kappa B decoy into the sciatic nerve suppresses mechanical allodynia and thermal hyperalgesia in a rat inflammatory pain model.

STUDY DESIGN: In vitro and in vivo study of a rat inflammatory pain model using nuclear factor-kappa B decoy. OBJECTIVES: To investigate transduction efficiency of nuclear factor-kappa B decoy into dorsal root ganglion, both in vivo and in vitro, and to assess the suppression of inflammatory pain by nuclear factor-kappa B decoy. SUMMARY OF BACKGROUND DATA: Transcription factor nuclear factor-kappa B is reported to play a crucial role in regulating pro-inflammatory cytokine gene expression. We hypothesized that inhibiting nuclear factor-kappa B gene expression with nuclear factor-kappa B decoy may suppress inflammatory pain. METHODS: Nuclear factor-kappa B decoy-fluorescein isothiocyanate (FITC) was induced in explant culture, endoneurally injected into the sciatic nerve, and its transduction efficiency into dorsal root ganglion measured. For behavioral testing, 12 rats received plantar injections of complete Freund's adjuvant and were divided into 3 groups: decoy group, single endoneural injection of 10 microL of nuclear factor-kappa B decoy (n = 4); saline group, single endoneural injection of 10 microL of saline (n = 4); and naïve group, untreated (n = 4). Behavioral testing was performed using von Frey filaments and a Hargreaves device with a heat source. RESULTS: Total transduction efficiency of nuclear factor-kappa B decoy-FITC was 53.6% in vitro and 20.5% in vivo. No statistical differences were observed with respect to types of cell size distributions of all FITC-positive neurons. In behavioral testing, withdrawal latencies or thresholds significantly differed between the decoy group and the saline group from 2 to 14 days after surgery in the mechanical allodynia experiments, and from 2 to 3 days after surgery in the thermal hyperalgesia experiments. CONCLUSIONS: Nuclear factor-kappa B decoy was conveyed and transduced into dorsal root ganglion both in vivo and in vitro. Additionally, nuclear factor-kappa B decoy reduced mechanical allodynia and thermal hyperalgesia in the rat inflammatory pain model, suggesting that inhibition of nuclear factor-kappa B with nuclear factor-kappa B decoy may represent a key mechanism for mediating inflammation or reducing inflammatory pain.

Up-regulation of acid-sensing ion channel 3 in dorsal root ganglion neurons following application of nucleus pulposus on nerve root in rats.

STUDY DESIGN: Immunocytochemistry for acid-sensing ion channel 3 (ASIC3) in neurons of rat dorsal root ganglions (DRGs) from animals exposed to a model of lumbar disc herniation. OBJECTIVE: To examine expression of ASIC3 in DRGs and the effect of a sodium channel blocker applied to the nerve root in a rat model of lumbar disc herniation. SUMMARY OF BACKGROUND DATA: Radicular pain is a common symptom of lumbar disc herniation in human beings. A depolarizing sodium channel gated by protons during tissue acidosis, ASIC3, is specifically expressed in sensory neurons. It has been associated with cardiac ischemic and inflammatory pain. We often perform spinal nerve root block for radicular pain using a sodium channel blocker, such as lidocaine; however, it has been unclear whether the effective period of this treatment is usually longer than the expected duration of efficacy. METHODS: For the lumbar disc herniation model, nucleus pulposus was harvested from the tail and applied to the L5 nerve root, and the nerve roots were pinched. We evaluated mechanical allodynia in sham-operated animals and a disc herniation model. Immunohistochemistry was used to examine ASIC3 expression in L5 DRGs. Finally, the effect of lidocaine on pain and ASIC3 expression in the disc herniation model was examined. RESULTS: Animals exposed to the lumbar disc herniation model showed allodynia for 8 days, and ASIC3 immunoreactivity was up-regulated in DRG neurons. After administration of lidocaine to spinal nerve roots affected by disc herniation, ASIC3 immunoreactivity was down-regulated in DRG neurons, and the level of mechanical allodynia was significantly decreased for 8 days. CONCLUSIONS: Our results suggest that ASIC3 in DRG neurons may play an important role in nerve root pain caused by lumbar disc herniation. Lidocaine decreased ASIC3 expression in DRG neurons and pain associated with the disc herniation model.

Rho-kinase inhibition enhances axonal regeneration after peripheral nerve injury.

In injured adult neurons, the process of axonal regrowth and reestablishment of the neuronal function have to be activated. We assessed in this study whether RhoA, a key regulator of neurite elongation, is activated after injury to the peripheral nervous system. RhoA is activated in motoneurons but not in Schwann cells after mouse sciatic nerve injury. To examine whether the activation of RhoA and its effector, Rho-kinase, retards axon regeneration of injured motoneurons, we employed a Rho-kinase inhibitor, fasudil. Amplitudes of distally evoked compound muscle action potentials are increased significantly faster after axonal injury in mice treated with fasudil compared with controls. Histological analysis shows that fasudil treatment increases the number of regenerating axons with large diameter, suggesting that axon maturation is facilitated by Rho-kinase inhibition. In addition, fasudil does not suppress the myelination of regenerating axons. These findings suggest that RhoA/Rho-kinase may be a practical molecular target to enhance axonal regeneration in human peripheral neuropathies.

Induction of repulsive guidance molecule in neurons following sciatic nerve injury.

Repulsive guidance molecule (RGM) is a protein implicated in both axonal guidance and neural tube closure. We examined the expression of RGMa in the spinal cord after the sciatic nerve crush by immunohistochemistry. Although there was no RGMa immunoreactivity under naïve conditions in the dorsal horn, a weak signal for RGMa was found at 24 h after the nerve crush, and this signal was progressively increased in the NeuN-positive neurons in the ipsilateral dorsal horn from superficial to deep layers at 10 days after surgery. In the neurons of the ipsilateral ventral horn, RGMa was also induced at 10 days after surgery, whereas no RGMa signal could be observed in naïve conditions or at 24 h after surgery. Thus, RGMa expression is upregulated both in the ipsilateral dorsal and ventral horns in response to the sciatic nerve injury. We next examined the effects of complete Freund's adjuvant (CFA)-induced inflammation on RGMa expression in the spinal cord. However, no RGMa expression was observed at 24 h and 10 days after the CFA injection in the dorsal horn, suggesting that RGMa is not involved in inflammation-induced gyperalgesia. Our present study demonstrates that induction of RGMa is associated with the peripheral nerve injury.

Exposure of the nucleus pulposus to the outside of the anulus fibrosus induces nerve injury and regeneration of the afferent fibers innervating the lumbar intervertebral discs in rats.

STUDY DESIGN: Using a retrograde tracing method and immunohistochemistry, we assessed the expression of activating transcription factor 3 (ATF3), a marker of nerve injury, and growth-associated protein 43 (GAP-43), a marker of axonal growth, in dorsal root ganglion (DRG) neurons innervating the lumbar intervertebral discs in rats. OBJECTIVES: To investigate ATF3 and GAP-43 expression in DRGs innervating the intervertebral discs after exposure of the nucleus pulposus to the outside of the anulus fibrosus. SUMMARY OF BACKGROUND DATA: Degeneration of lumbar intervertebral discs is considered as a cause of low back pain. We speculated that exposure of the nucleus pulposus to the outside of the anulus fibrosus may induce nerve injury and ingrowth into the disc. METHODS: A neurotracer, Fluoro-Gold (F-G), was applied to the ventral aspect of L5-L6 intervertebral discs in 20 rats. The rats were classified into 2 groups: an NP group whose disc was punctured to expose the nucleus pulposus (n = 10) and a sham-operated group whose anulus fibrosus surface was scratched superficially (n = 10). Ten days after surgery, bilateral L1-L5 DRGs were processed for staining of ATF3 and GAP-43. RESULTS: In the NP group, 13.9% +/- 2.9% of the F-G-labeled neurons innervating the discs were positive for ATF3, while 19.3% +/- 2.7% were positive for GAP-43. In contrast, in the sham-operated group, only 0.8% +/- 0.4% of the F-G-labeled neurons were positive for ATF3 while 7.4% +/- 1.7% were positive for GAP-43. The percentage of both ATF3-immunoreactive (IR) and GAP-43-IR neurons in the NP group was significantly higher than in the sham-operated group (P < 0.05). CONCLUSIONS: ATF3-IR and GAP-43-IR neurons were significantly increased in the NP group. These results suggested that exposure of the nucleus pulposus to the outside of the anulus fibrosus induced nerve injury and in growth into the discs. These findings may explain discogenic lower back pain in patients with lumbar disc degeneration.

Up-regulation of TNFalpha in DRG satellite cells following lumbar facet joint injury in rats.

The rat L5/6 facet joint, from which low back pain can originate, is multisegmentally innervated from the L1 to L5 dorsal root ganglia (DRG). Sensory fibers from the L1 and L2 DRG are reported to non-segmentally innervate the paravertebral sympathetic trunks, while those from the L3 to L5 DRGs segmentally innervate the L5/6 facet joint. Tumor necrosis factor alpha (TNFalpha) is a mediator of peripheral and central nervous system inflammatory response and plays a crucial role in injury and its pathophysiology. In the current study, change in TNFalpha in sensory DRG neurons innervating the L5/6 facet joint following facet joint injury was investigated in rats using a retrograde neurotransport method and immunohistochemistry. Neurons innervating the L5/6 facet joints, retrogradely labeled with fluoro-gold (FG), were distributed throughout DRGs from L1 to L5. Most DRG FG-labeled neurons innervating L5/6 facet joints were immunoreactive (IR) for TNFalpha before and after injury. In the DRG, glial fibrillary acidic protein (GFAP)-IR satellite cells emerged and surrounded neurons innervating L5/6 facet joints after injury. These satellite cells were also immunoreactive for TNFalpha. The numbers of activated satellite cells and TNFalpha-IR satellite cells were significantly higher in L1 and L2 DRG than in L3, L4, and L5 DRG. These data suggest that up-regulation of glial TNFalpha may be involved in the pathogenesis of facet joint pain.

RGMa inhibition promotes axonal growth and recovery after spinal cord injury.

Repulsive guidance molecule (RGM) is a protein implicated in both axonal guidance and neural tube closure. We report RGMa as a potent inhibitor of axon regeneration in the adult central nervous system (CNS). RGMa inhibits mammalian CNS neurite outgrowth by a mechanism dependent on the activation of the RhoA-Rho kinase pathway. RGMa expression is observed in oligodendrocytes, myelinated fibers, and neurons of the adult rat spinal cord and is induced around the injury site after spinal cord injury. We developed an antibody to RGMa that efficiently blocks the effect of RGMa in vitro. Intrathecal administration of the antibody to rats with thoracic spinal cord hemisection results in significant axonal growth of the corticospinal tract and improves functional recovery. Thus, RGMa plays an important role in limiting axonal regeneration after CNS injury and the RGMa antibody offers a possible therapeutic agent in clinical conditions characterized by a failure of CNS regeneration.

Tumor necrosis factor-immunoreactive cells and PGP 9.5-immunoreactive nerve fibers in vertebral endplates of patients with discogenic low back Pain and Modic Type 1 or Type 2 changes on MRI.

STUDY DESIGN: Immunohistochemistry for tumor necrosis factor (TNF) and protein gene product (PGP) 9.5 in vertebral endplates of patients with discogenic low back pain and Modic Type 1 or Type 2 endplate changes on MRI. OBJECTIVES: To examine whether inflammatory cytokines and nerve in-growth into the vertebral endplate are associated with discogenic low back pain. SUMMARY AND BACKGROUND DATA: Degenerated discs and endplate abnormalities can be a cause of discogenic low back pain. However, the presence of TNF-immunoreactive cells and PGP 9.5-immunoreactive nerve fibers has not been studied in patients with discogenic low back pain and endplate changes on MRI. METHODS: Eighteen endplates showing either normal intensity signals on MRI (endplate change -), Modic Type 1 signals (low intensity on T1-weighted spin-echo images), or Modic Type 2 signals (high intensity) from patients with discogenic low back pain (n = 14) or controls requiring surgery for other back problems (n = 4; scoliosis and traumatic injury of vertebra) were harvested during surgery. Endplates were immunostained using antibodies to TNF and PGP 9.5 and immunostained cells and nerve fibers in the endplates were counted. RESULTS: Vertebral endplates from patients with Modic Type 1 or Type 2 endplate changes on MRI had significantly more PGP 9.5-immunoreactive nerve fibers and TNF-immunoreactive cells in comparison with patients with normal endplates on MRI (P < 0.01). The number of TNF-immunoreactive cells in endplates exhibiting Modic Type 1 changes was significantly higher than in endplates exhibiting Modic Type 2 changes (P < 0.05). CONCLUSIONS: The results suggest that endplate abnormalities are related to inflammation and axon growth induced by TNF. TNF expression and PGP 9.5-positive nerve in-growth in abnormal endplates may be a cause of low back pain.

Adenoviral gene transfer in the peripheral nervous system.

BACKGROUND: Viral vectors have gained widespread use as vehicles for somatic gene transfer, and the targeted expression of foreign proteins by these vectors offers advantages over the systemic administration of the drugs in some therapeutic situations. Selective virus-mediated gene transfer to the peripheral nervous system (PNS), however, remains to be established. There are no data showing efficiency of protein transduction in the PNS, which consists of a variety of cell types, many of which are postmitotic. METHODS: We prepared the first-generation replication-deficient recombinant adenovirus vectors engineered to express LacZ. Eight-week-old Wister rats were used in this study. Adenovirus vector (5 microl) containing the LacZ gene (5 x 10(8) pfu) was injected into rat sciatic nerves or the dorsal root ganglia at the level of L5. The sciatic nerves, the dorsal root ganglia, and the spinal cords were obtained 7, 14, 21, and 28 days after injection. Expression of LacZ was assessed by X-gal histochemistry and beta-gal immunohistochemistry. RESULTS: Following injection of the adenovirus carrying the LacZ gene into the sciatic nerve, LacZ expression was seen mainly in the Schwann cells and the small neurons in the dorsal root ganglion. In contrast, expression was observed in the primary nerve terminals of the spinal dorsal horn and the small to large dorsal root ganglion neurons and the Schwann cells after injection of the vectors into the L5 dorsal root ganglion. There were no side effects in rats with injection in the dorsal root ganglia or the sciatic nerve. CONCLUSIONS: The present study shows efficient protein transduction by adenovirus vectors in the PNS. It is noted that injection of the virus into the dorsal root ganglia leads to extensive expression of LacZ in the spinal cord, the dorsal root ganglia, and the sciatic nerves.

Extracellular signal-regulated kinase mitogen-activated protein kinase activation in the dorsal root ganglion (DRG) and spinal cord after DRG injury in rats.

STUDY DESIGN: We investigated the extracellular signal-regulated kinase (ERK) activation by immunohistochemically detecting phosphorylated ERK (pERK) in the dorsal root ganglion (DRG) and spinal cord. OBJECTIVE: To clarify the ERK activation in the rat nervous system following DRG injury. SUMMARY OF BACKGROUND DATA: Radicular pain is known to be associated with DRG injury caused by intervertebral disc herniation. ERK is activated by phosphorylation in the DRG and spinal cord by noxious stimuli, which are related to pain hypersensitivity. METHODS: From 2 minutes to 24 hours after the left L4 DRG crush injury, L4 DRGs and spinal cords were resected to prepare serial sections, which were investigated immunohistochemically. RESULTS: In the DRG, ERK activation was detected in neurons and satellite cells at 2 minutes; the former was maintained at increased levels for 20 minutes, and the latter for 4 hours. At 30 minutes, pERK immunoreactivity was observed in Schwann cells, which continued for up to 24 hours. In the spinal cord, pERK-positive neurons were detected at 2 minutes, and the pERK levels were maintained at increased levels for 20 minutes. CONCLUSIONS: Profiles of pERK induction in neurons after DRG injury were similar between the DRG and spinal cord, whereas pERK induction in the satellite cells was more long lasting. The pERK induction in Schwann cells in the DRG was late onset and the most long lasting.

c-Jun N-terminal kinase activation in dorsal root ganglion contributes to pain hypersensitivity.

Inflammatory pain, characterized by a decrease in the nociceptive threshold, arises through the actions of inflammatory mediators. Mitogen-activated protein kinase cascades participate in peripheral nociceptive sensitization. We examined the involvement of c-Jun N-terminal kinase (JNK) in the dorsal root ganglion (DRG) in the early phase of inflammation-induced hyperalgesia. An intra-plantar (i.pl.) injection of complete Freund's adjuvant induced the activation of JNK in DRG neurons within 30 min. Pre-treatment as well as post-treatment of rats with a JNK inhibitor, SP600125, significantly attenuated thermal hyperalgesia, as assessed by paw-withdrawal latency, and the upregulation of c-fos immunoreactivity in dorsal horn neurons. An i.pl. injection of nerve growth factor (NGF) also induced the phosphorylation of JNK as well as thermal hyperalgesia, and SP600125 improved hyperalgesia. Inhibitor experiments suggest that JNK and extracellular signal-regulated protein kinase act on primary nociceptive neurons synergistically. These findings demonstrate that JNK is a therapeutic target for treating inflammation-induced pain hypersensitivity.

Characteristics of sensory DRG neurons innervating the lumbar facet joints in rats.

The rat L5/6 facet joint, from which low-back pain can originate, is multisegmentally innervated from the L1 to L5 dorsal root ganglions (DRGs). Sensory fibers from the L1 and L2 DRGs are reported to non-segmentally innervate the paravertebral sympathetic trunks, whilst those from the L3 to L5 DRGs segmentally innervate the L5/6 facet joint. In the current study, characteristics of sensory DRG neurons innervating the L5/6 facet joint were investigated in rats, using a retrograde neurotransport method, lectin affinity- and immuno-histochemistry. We used four markers: (1) calcitonin gene-related peptide (CGRP) as a marker of small peptide containing neurons, (2) the glycoprotein binding the isolectin from Griffonia simplicifolia (IB4) or (3 the purinergic P2X(3) receptor for small, non-peptide containing neurons, and (4) neurofilament 200 (NF200) for small and large myelinated fibers. IB4-binding and CGRP and P2X(3) receptor containing neurons are typically involved in pain sensation, whereas NF200 is associated with pain and proprioception. Neurons innervating the L5/6 facet joints, retrogradely-labeled with fluoro-gold (FG), were distributed throughout DRGs from L1 to L5. Of FG-labeled neurons, the ratios of NF200 immunoreactive (IR) neurons and CGRP-IR neurons were 37% and 35% respectively. The ratio of IB4-binding and P2X(3) receptor-IR neurons was 10%, significantly less than the ratio of CGRP-IR neurons to FG-labeled neurons. The ratios of IB4-binding and P2X(3) receptor-IR neurons were significantly higher, and that of CGRP-IR neurons was significantly less in L1 and L2 DRGs than those in L3, L4 or L5 DRGs. Under physiological conditions in rats, DRG neurons transmit several types of sensations, such as proprioception or nociception of the facet joint. Most neurons transmitting pain are CGRP-IR peptide-containing neurons. They may have a more significant role in pain sensation in the facets via peptidergic DRG neurons.