c-Fos Expression In Dorsal Horn Research Articles

Differential Activation of pERK1/2 and c-Fos Following Injury to Different Regions of Primary Sensory Neuron.

Nerve injury causes hyperexcitability of the dorsal root ganglion (DRG) and spinal dorsal horn (DH) neurons, which results in neuropathic pain. We have previously demonstrated that partial dorsal rhizotomy (PDR) produced less severe pain-like behavior than chronic constriction injury (CCI) or chronic compression of DRG (CCD) and did not enhance DRG neuronal excitability. However, the mechanisms underlying such discrepancy remain unclear. This study was designed to compare the activation of phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2) in DRG and DH, and c-Fos in DH following treatments of CCI, CCD, and PDR. We confirmed that thermal hyperalgesia produced by PDR was less severe than that produced by CCI or CCD. We showed that pERK1/2 in DRG and DH was greatly activated by CCI or CCD, whereas PDR produced only transient and mild pERK1/2 activation. CCI, CCD, and PDR induced robust c-Fos expression in DH; nevertheless, c-Fos+ neurons following PDR were much fewer than that following CCI or CCD. Blocking retrograde axonal transport by colchicine proximal to the CCI injury site diminished thermal hyperalgesia and inhibited pERK1/2 and c-Fos activation. These findings demonstrate that less severe pain-like behavior produced by PDR than CCI or CCD attributes to less activation of pERK1/2 and c-Fos. Such neurochemical activation partially relies on retrograde axonal transport of certain “injury signals” from the peripheral injured site to DRG somata.

Development and Characterization of a Novel, Anatomically Relevant Rat Model of Acute Postoperative Pain

Acute postoperative pain remains a significant health care issue. Development of anatomically relevant animal models of postoperative pain, with improved predictive validity, would advance understanding of postoperative pain mechanisms and improve treatment outcomes. This study aimed to develop, characterize, and validate a rat model of acute postoperative pain associated with inguinal hernia repair based on the Lichtenstein inguinal hernia repair procedure (without hernia induction). We hypothesized that the surgery would result in reduced spontaneous locomotor activity, which would represent a pain-related phenotype. Postsurgical characterization involved extensive monitoring of home cage and open field locomotor activity, as well as mechanical hypersensitivity and assessment of c-Fos expression in the dorsal horn of the spinal cord. In pharmacologic validation studies, rats received morphine, carprofen, or paracetamol 1 hour before, and/or immediately after, surgery. Rats that underwent hernia repair surgery exhibited significantly lower horizontal and vertical activities in the home cage and open field in the early postsurgical period, compared with sham rats or rats that underwent skin incision only. Morphine, carprofen, and paracetamol attenuated the surgery-induced reductions in locomotor activity, to varying degrees. Surgery was associated with significantly increased c-Fos expression in the ipsilateral dorsal horn of the spinal cord, an effect attenuated by carprofen treatment. These results support the development and characterization of a novel, anatomically relevant animal model of acute postoperative pain that may facilitate development of improved treatment regimens. PerspectiveAcute pain following inguinal hernia repair can be difficult to treat. Here we report, for the first time, the development of a novel, anatomically relevant rat model to facilitate improved understanding and treatment of acute postoperative pain following inguinal hernia repair.

MP4-19 EFFECT OF SKIN TRANSIENT RECEPTOR POTENTIAL MELASTATIN 8 CHANNEL STIMULATION ON C-FOS EXPRESSION IN L6 SPINAL CORD

You have accessJournal of UrologyUrodynamics/Incontinence/Female Urology: Basic Research II1 Apr 2014MP4-19 EFFECT OF SKIN TRANSIENT RECEPTOR POTENTIAL MELASTATIN 8 CHANNEL STIMULATION ON C-FOS EXPRESSION IN L6 SPINAL CORD Hitoshi Yokoyama, Tetsuya Imamura, Teruyuki Ogawa, Osamu Ishizuka, and Osamu Nishizawa Hitoshi YokoyamaHitoshi Yokoyama More articles by this author , Tetsuya ImamuraTetsuya Imamura More articles by this author , Teruyuki OgawaTeruyuki Ogawa More articles by this author , Osamu IshizukaOsamu Ishizuka More articles by this author , and Osamu NishizawaOsamu Nishizawa More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.219AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Menthol is an agonist of the transient receptor potential melastatin 8 (TRPM8) channel. It is reported that applying menthol onto back skin elicits detrusor overactivity and urinary frequency in conscious rat. However, the precise mechanism of menthol-induced detrusor overactivity is still unknown. C-fos expression is thought to be activated transsynaptically by peripheral stimuli in the central nerve system (CNS). Moreover, noxious stimulation of the bladder elicited c-fos expression in dorsal horn of L6 spinal cord innervating the bladder. In the current study, we investigated the effect of skin application of menthol on CNS by examining c-fos expression in dorsal horn of L6 spinal cord in rat model. METHODS Female Sprague-Dawley rats, weighing 250-270g, were used in this study. Three days prior to the experiment, hip area was shaved by an electric hair clipper. Experiment 1: The rats were randomly separated into two groups; menthol- (n=4) and saline-treatment (n=4) group. Menthol solution (90%) or saline was applied onto the shaved area by spraying every 30 min for 2 hrs at room temperature (27±2°C). Experiment 2: After BCTC (n=6), which is the TRPM8 channel antagonist, or saline (n=6) was administrated intraperitoneally, menthol was applied in the same manner. Just after the treatments, L6 spinal cords were removed, and then expression levels of c-fos mRNA (in Experiment 1 and 2) and protein (in Experiment 1) were evaluated by real-time reverse-transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry, respectively. RESULTS Experiment 1: Expression level of c-fos mRNA in L6 spinal cord in menthol-treated rats was significantly elevated compared to saline-treated rats (P=0.01). In immunohistochemistry, the number of c-fos positive cell in dorsal horn of L6 spinal cord was significantly greater in menthol-treated rats than in saline-treated rats (P<0.01). Experiment 2: Intraperitoneal administration of BCTC reduced the level of c-fos mRNA expression in L6 spinal cord after the menthol application significantly compared to saline administration (P<0.05). CONCLUSIONS This study showed that skin TRPM 8 channels stimulated with menthol spray elevated c-fos expression levels in the dorsal horn of L6 spinal cord. Therefore, menthol-induced detrusor overactivity was composed of the activation of central nerve pathways through TRPM 8 channels. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e50 Peer Review Report Advertisement Copyright & Permissions© 2014MetricsAuthor Information Hitoshi Yokoyama More articles by this author Tetsuya Imamura More articles by this author Teruyuki Ogawa More articles by this author Osamu Ishizuka More articles by this author Osamu Nishizawa More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Dynamic variations of c‐Fos expression in the spinal cord exposed to intramuscular hypertonic saline‐induced muscle nociception

Numerous studies focus on intramuscular (i.m.) injection of hypertonic saline-induced muscle pain and nociception. The spatio-temporal characteristics and dynamic variation of spinal neuronal activities elicited by i.m. hypertonic saline remain unknown. The spatio-temporal variations of c-Fos expression in the lumbar spinal cord exposed to i.m. injection of 5.8% saline were investigated in male rats. After a unilateral i.m. 5.8% saline injection, c-Fos expression in dorsal horn of spinal L4-6 segments was significantly enhanced bilaterally (p < 0.05 and p < 0.001). These 5.8% saline-induced bilateral spinal Fos expression occurred rapidly 0.5 h following the i.m. injection, and reached the peak levels within 1 h, which declined gradually and returned to the control levels within 8 h. Compared with intact rats without i.m. insults, no significant influence of the spinalization on spinal c-Fos expression was found. However, the 5.8% saline-induced increases in Fos expression in intact and spinalized rats differed significantly. During muscle nociception, the c-Fos expression within the superficial layer (laminae I-II) and the deep layer (laminae V-VI) in spinalized rats were significantly lower and higher than that of in intact rats (p < 0.05 and p < 0.001). Fentanyl (20 μg/kg, intraperitoneal) completely attenuated the 5.8% saline intramuscularly induced increases in c-Fos expression in laminae III-VI (p < 0.001), but not laminae I-II. It is suggested that spinal nociceptive neuronal activities in superficial and deep layers may differently be modulated by endogenous descending facilitation and inhibition, respectively.

An In Vivo Mouse Model of Long-Term Potentiation at Synapses between Primary Afferent C-Fibers and Spinal Dorsal Horn Neurons: Essential Role of Ephb1 Receptor

BackgroundLong-term potentiation (LTP), a much studied cellular model of synaptic plasticity, has not been demonstrated at synapses between primary afferent C-fibers and spinal dorsal horn (DH) neurons in mice in vivo. EphrinB-EphB receptor signaling plays important roles in synaptic connection and plasticity in the nervous system, but its role in spinal synaptic plasticity remains unclear.ResultsThis study characterizes properties of LTP at synapses of C-fibers onto neurons in the superficial DH following high-frequency stimulation (HFS) of a peripheral nerve at an intensity that activates C-fibers and examines associated activation of Ca2+/calmodulin-activated protein kinase II (p-CaMKII), extracellular signal-regulated kinase (p-ERK) and the cyclic AMP response element binding protein (p-CREB) and expression of c-Fos, and it investigates further roles for the EphB1 receptor in LTP. HFS induced LTP within 5 min and lasts for 3–8 h during the period of recording and resulted in upregulation of p-CaMKII, p-ERK and p-CREB protein levels in the spinal cord and expression of c-Fos in DH. Intrathecal pretreatment of MK-801 or EphB2-Fc prevented LTP and significantly reduced upregulation of p-CaMKII, p-ERK, p-CREB and c-Fos. Further, targeted mutation of EphB1 receptor prevented induction of LTP and associated increases in phosphorylation of CaMKII, ERK, and CREB.ConclusionThis study provides an in vivo mouse model of LTP at synapses of C-fibers onto the superficial DH neurons that will be valuable for studying the DH neuron excitability and their synaptic plasticity and hyperalgesia. It further takes advantage of examining functional implications of a specific gene targeted mice and demonstrates that the EphB1 receptor is essential for development of LTP.

Change with age in muscular mechanical hyperalgesia after lengthening contraction in rats

To determine whether there is any change by aging in mechanical hyperalgesia (delayed onset muscle soreness) after lengthening contraction (LC, also termed as eccentric contraction), we applied LC to the dorsi-flexors of the hind legs in young (7-week-old) and aged (130-week-old) rats and examined the change in mechanical withdrawal threshold of the exercised muscle with a Randall–Selitto apparatus and by c-Fos expression in the dorsal horn. The baseline mechanical withdrawal threshold did not differ among two age groups. One day after LC the withdrawal threshold started to decrease in both age groups, however, the duration of decreased withdrawal threshold was different: young rats had their withdrawal threshold lowered only for 3 days after LC while that of aged rats remained lowered two more days, showing delayed recovery in aged rats. Induction of c-Fos expression in the spinal dorsal horn by compression of the muscle was examined in aged animals 3 days after LC. Significantly larger numbers of c-Fos positive neurons was observed in the superficial dorsal horn than the control animals (no treatment). This increase was observed not only in L4 but also in L5, a wider distribution than in young animals (L4 only) in our previous report [Taguchi, T., Matsuda, T., Tamura, R., Sato, J., Mizumura, K., 2005a. Muscular mechanical hyperalgesia revealed by behavioural pain test and c-Fos expression in the spinal dorsal horn after eccentric contraction in rats. J. Physiol. (Lond.) 564 259–268].

Changes in tactile stimuli-induced behavior and c-Fos expression in the superficial dorsal horn and in parabrachial nuclei after sciatic nerve crush.

Neurons in the superficial laminae of the dorsal horn are dominated by input from peripheral nociceptors. Following peripheral nerve injury, low threshold mechanoreceptive Abeta-fibers sprout from their normal termination site in laminae III/IV into laminae I-II and this structural reorganization may contribute to neuropathic tactile pain hypersensitivity. We have now investigated whether a sciatic nerve crush injury alters the behavioral response in rats to tactile stimuli and whether this is associated with a change in the pattern of c-Fos expression in the dorsal horn and the parabrachial area of the brainstem. Sciatic nerve crush resulted in a patchy but marked tactile allodynia manifesting first at 3 weeks and persisting for up to 52 weeks. C-Fos expression in the dorsal horn and parabrachial region was never observed on brushing the skin of the sciatic nerve territory in animals with intact nerves, but was found after sciatic nerve crush with peripheral regeneration. We conclude that after nerve injury, low threshold mechanoreceptor fibers may play a major role in producing pain-related behavior by activating normally nociceptive-specific regions of the central nervous system such as the superficial laminae of the dorsal horn and the parabrachial area.

Peripheral nitric oxide contributes to both formalin‐ and NMDA‐induced activation of nociceptors: An immunocytochemical study in rats

Nociceptive c-fos expressions in the dorsal horn following intraplantar injection of two kinds of algogenic agents combined with different doses of nitric oxide (NO) synthase inhibitor (Nω-nitro-L-arginine methyl ester (L-NAME)) or of NO donor (L-arginine) were used to explore if NO was involved in the activation of peripheral nociceptors. The results showed that: 1) combined injections of L-NAME with formalin into the plantar aspect of one hindpaw of normal rats elicited a dose-dependent suppression of c-fos expression as compared to that induced by formalin alone; 2) combined injections of L-arginine with formalin elicited considerable enhancement of c-fos expression when the dosages of L-arginine were less than 20 μmol, while it elicited marked suppression of c-fos expression when the dosages were in the range from 50 to 100 μmol; and 3) combined injection of L-NAME with NMDA, a selective agonist for NMDA receptors, into the hindpaw could also inhibit the NMDA-induced c-fos expression in the spinal dorsal horn. These results suggest that endogenously generated concentrations of nitric oxide may enhance the initiation of nociceptive inputs of peripheral nociceptors following local injection of formalin or NMDA. J. Neurosci. Res. 57:824–829, 1999. © 1999 Wiley-Liss, Inc.

Peripheral nitric oxide contributes to both formalin- and NMDA-induced activation of nociceptors: An immunocytochemical study in rats

Nociceptive c-fos expressions in the dorsal horn following intraplantar injection of two kinds of algogenic agents combined with different doses of nitric oxide (NO) synthase inhibitor (N(omega)-nitro-L-arginine methyl ester (L-NAME)) or of NO donor (L-arginine) were used to explore if NO was involved in the activation of peripheral nociceptors. The results showed that: 1) combined injections of L-NAME with formalin into the plantar aspect of one hindpaw of normal rats elicited a dose-dependent suppression of c-fos expression as compared to that induced by formalin alone; 2) combined injections of L-arginine with formalin elicited considerable enhancement of c-fos expression when the dosages of L-arginine were less than 20 micromol, while it elicited marked suppression of c-fos expression when the dosages were in the range from 50 to 100 micromol; and 3) combined injection of L-NAME with NMDA, a selective agonist for NMDA receptors, into the hindpaw could also inhibit the NMDA-induced c-fos expression in the spinal dorsal horn. These results suggest that endogenously generated concentrations of nitric oxide may enhance the initiation of nociceptive inputs of peripheral nociceptors following local injection of formalin or NMDA.