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Spinal Cord Slices (spinal + cord_slice)
Selected AbstractsLong-range oscillatory Ca2+ waves in rat spinal dorsal hornEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2005Ruth Ruscheweyh Abstract Synchronous activity of large populations of neurons shapes neuronal networks during development. However, re-emergence of such activity at later stages of development could severely disrupt the orderly processing of sensory information, e.g. in the spinal dorsal horn. We used Ca2+ imaging in spinal cord slices of neonatal and young rats to assess under which conditions synchronous activity occurs in dorsal horn. No spontaneous synchronous Ca2+ transients were detected. However, increasing neuronal excitability by application of 4-aminopyridine after pretreatment of the slice with blockers of (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate, ,-aminobutyric acid (GABA)A and glycine receptors evoked repetitive Ca2+ waves in dorsal horn. These waves spread mediolaterally with a speed of 1.0 ± 0.1 mm/s and affected virtually every dorsal horn neuron. The Ca2+ waves were associated with large depolarizing shifts of the membrane potential of participating neurons and were most likely synaptically mediated because they were abolished by blockade of action potentials or N -methyl- d -aspartate (NMDA) receptors. They were most pronounced in the superficial dorsal horn and absent from the ventral horn. A significant proportion of the Ca2+ waves spread to the contralateral dorsal horn. This seemed to be enabled by disinhibition as primary afferent-induced dorsal horn excitation crossed the midline only when GABAA and glycine receptors were blocked. Interestingly, the Ca2+ waves occurred under conditions where AMPA/kainate receptors were blocked. Thus, superficial dorsal horn NMDA receptors are able to sustain synchronous neuronal excitation in the absence of functional AMPA/kainate receptors. [source] Intracellular glutathione mediates the denitrosylation of protein nitrosothiols in the rat spinal cordJOURNAL OF NEUROSCIENCE RESEARCH, Issue 3 2009Jorge M. Romero Abstract Protein S-nitrosothiols (PrSNOs) have been implicated in the pathophysiology of neuroinflammatory and neurodegenerative disorders. Although the metabolically instability of PrSNOs is well known, there is little understanding of the factors involved in the cleavage of S-NO linkage in intact cells. To address this issue, we conducted chase experiments in spinal cord slices incubated with S-nitrosoglutathione (GSNO). The results show that removal of GSNO leads to a rapid disappearance of PrSNOs (t½ , 2 hr), which is greatly accelerated when glutathione (GSH) levels are raised with the permeable analogue GSH ethyl ester. Moreover, PrSNOs are stable in the presence of the GSH depletor diethyl maleate, indicating that GSH is critical for protein denitrosylation. Inhibition of GSH-dependent enzymes (glutathione S-transferase, glutathione peroxidase, and glutaredoxin) and enzymes that could mediate denitrosylation (alcohol dehydrogense-III, thioredoxin and protein disulfide isomerase) do not alter the rate of PrSNO decomposition. These findings and the lack of protein glutathionylation during the chase indicate that most proteins are denitrosylated via rapid transnitrosylation with GSH. The differences in the denitrosylation rate of individual proteins suggest the existence of additional structural factors in this process. This study is relevant to our recent discovery that PrSNOs accumulate in the central nervous system of patients with multiple sclerosis. © 2008 Wiley-Liss, Inc. [source] Glutamate-mediated astrocyte-to-neuron signalling in the rat dorsal hornTHE JOURNAL OF PHYSIOLOGY, Issue 5 2010Rita Bardoni By releasing neuroactive agents, including proinflammatory cytokines, prostaglandins and neurotrophins, microglia and astrocytes are proposed to be involved in nociceptive transmission, especially in conditions of persistent, pathological pain. The specific action on dorsal horn neurons of agents released from astrocytes, such as glutamate, has been, however, poorly investigated. By using patch-clamp and confocal microscope calcium imaging techniques in rat spinal cord slices, we monitored the activity of dorsal horn lamina II neurons following astrocyte activation. Results obtained revealed that stimuli that triggered Ca2+ elevations in astrocytes, such as the purinergic receptor agonist BzATP and low extracellular Ca2+, induce in lamina II neurons slow inward currents (SICs). Similarly to SICs triggered by astrocytic glutamate in neurons from other central nervous system regions, these currents (i) are insensitive to tetrodotoxin (TTX), (ii) are blocked by the NMDA receptor (NMDAR) antagonist d -AP5, (iii) lack an AMPA component, and (iv) have slow rise and decay times. Ca2+ imaging also revealed that astrocytic glutamate evokes NMDAR-mediated episodes of synchronous activity in groups of substantia gelatinosa neurons. Importantly, in a model of peripheral inflammation, the development of thermal hyperalgesia and mechanical allodynia was accompanied by a significant increase of spontaneous SICs in dorsal horn neurons. The NMDAR-mediated astrocyte-to-neuron signalling thus represents a novel pathway that may contribute to the control of central sensitization in pathological pain. [source] Protein kinase C, mediates ethanol withdrawal hyper-responsiveness of NMDA receptor currents in spinal cord motor neuronsBRITISH JOURNAL OF PHARMACOLOGY, Issue 3 2005Hui-Fang Li 1The present studies were designed to test the hypothesis that neuronal-specific protein kinase C, (PKC,) plays a critical role in acute ethanol withdrawal hyper-responsiveness in spinal cord. 2Patch-clamp studies were carried out in motor neurons in neonatal rat spinal cord slices. Postsynaptic currents were evoked by brief pulses of 2 mMN -methyl- D -aspartic acid (NMDA) in the presence of bicuculline methiodide 10 ,M; strychnine 5 ,M and tetrodotoxin 0.5 ,M. 3Both ethanol depression and withdrawal hyper-responsiveness of NMDA-evoked currents are dependent on increases in intracellular Ca2+. Blocking intracellular increase in Ca2+ by 30 mM 1,2-bis(2-aminophenoxy)-ethane- N,N,N,,N,-tetraacetic acid (BAPTA) not only decreased the ethanol-induced depression of NMDA-evoked currents (33±5% in control vs 20±3% in BAPTA, P<0.05) but also eliminated acute ethanol withdrawal hyper-responsiveness. 4Immunohistochemistry studies revealed that neonatal spinal cord motor neurons contain an abundance of nuclear PKC,. 5Exposure to ethanol (100 mM) induced PKC, translocation from the nucleus to cytoplasm in motor neurons. Pretreatment with the , -isozyme-specific peptide PKC inhibitor, ,V5-3, blocked ethanol-induced translocation and also blocked withdrawal hyper-responsiveness. 6The results show that PKC, mediates ethanol withdrawal hyper-responsiveness in spinal motor neurons; the results may be relevant to some symptoms of ethanol withdrawal in vivo. British Journal of Pharmacology (2005) 144, 301,307. doi:10.1038/sj.bjp.0706033 [source] Effects of endomorphin on substantia gelatinosa neurons in rat spinal cord slicesBRITISH JOURNAL OF PHARMACOLOGY, Issue 6 2003Su-Ying Wu Whole-cell patch recordings were made from substantia gelatinosa (SG) neurons in transverse lumbar spinal cord slices of 15- to 30-day-old rats. Endomorphin 1 (EM-1) or EM-2 (10 ,M) hyperpolarized or induced an outward current in 26 of the 66 SG neurons. The I,V relationship showed that the peptide activates an inwardly rectifying K+ current. EM-1 or EM-2 (0.3,10 ,M) suppressed short-latency excitatory postsynaptic currents (EPSCs) and long-latency inhibitory postsynaptic currents (IPSCs) in nearly all SG neurons tested or short-latency IPSCs in six of the 10 SG neurons. [Met5] enkephalin or [D -Ala2, N -Me-Phe4, Gly5 -ol]-enkephalin (DAMGO) (1,10 ,M) depressed EPSCs and IPSCs. EM-1 or EM-2 depressed synaptic responses without causing a significant change in holding currents or inward currents induced by glutamate. Glutamate also evoked a short-latency outward current in five SG neurons or a biphasic current in two neurons; the outward current was blocked by tetrodotoxin (TTX, 0.3 ,M) or bicuculline (10 ,M). EM-1 or DAMGO (1 or 5 ,M) attenuated the glutamate-evoked outward or biphasic currents in four of the seven SG neurons. EM-1 (1 ,M) reduced the frequency, but not the amplitude of miniature EPSCs or miniature IPSCs. Naloxone (1 ,M) or the selective , -opioid receptor antagonist , -funaltrexamine (, -FNA, 25 ,M) antagonized the action of EM; EM-induced hyperpolarizations persisted in the presence of the , -opioid receptor antagonist (nor-binaltorphimine dihydrochloride, 1 ,M) and/or , -opioid receptor antagonist (naltrindole hydrochloride, 1 ,M). It may be concluded that EM acting on , -opioid receptors hyperpolarizes a population of SG neurons by activating an inwardly rectifying K+ current, and attenuates excitatory and inhibitory synaptic currents evoked in a population of SG neurons, probably by a presynaptic site of action. British Journal of Pharmacology (2003) 140, 1088,1096. doi:10.1038/sj.bjp.0705534 [source] | ||||||||||