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Laminae I (lamina + i)
Terms modified by Laminae I Selected AbstractsCocaine- and amphetamine-regulated transcript peptide (CART) is present in peptidergic C primary afferents and axons of excitatory interneurons with a possible role in nociception in the superficial laminae of the rat spinal cordEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2007Márk Kozsurek Abstract Cocaine- and amphetamine-regulated transcript peptides (CART) have been implicated in the regulation of several physiological functions, including pain transmission. A dense plexus of CART-immunoreactive fibres has been described in the superficial laminae of the spinal cord, which are key areas in sensory information and pain processing. In this study, we used antibody against CART peptide, together with markers for various types of primary afferents, interneurons and descending systems to determine the origin of the CART-immunoreactive axons in the superficial laminae of the rat spinal cord. Calcitonin gene-related peptide (CGRP), a marker for peptidergic primary afferents in the dorsal horn, was present in 72.6% and 34.8% of CART-immunoreactive axons in lamina I and II, respectively. The majority of these fibres also contained substance P (SP), while a few were somatostatin (SOM)-positive. The other subpopulation of CART-immunoreactive boutons in lamina I and II also expressed SP and/or SOM without CGRP, but contained vesicular glutamate transporter 2, which is present mainly in excitatory interneuronal terminals. Our data demonstrate that the majority of CART-immunoreactive axons in the spinal dorsal horn originate from peptidergic nociceptive primary afferents, while the rest arise from excitatory interneurons that contain SP or SOM. This strongly suggests that CART peptide can affect glutamatergic neurotransmission as well as the release and effects of SP and SOM in nociception and other sensory processes. [source] Pre- and postsynaptic contributions of voltage-dependent Ca2+ channels to nociceptive transmission in rat spinal lamina I neuronsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2004B. Heinke Abstract Activation of voltage-dependent Ca2+ channels (VDCCs) is critical for neurotransmitter release, neuronal excitability and postsynaptic Ca2+ signalling. Antagonists of VDCCs can be antinociceptive in different animal pain models. Neurons in lamina I of the spinal dorsal horn play a pivotal role in the processing of pain-related information, but the role of VDCCs to the activity-dependent Ca2+ increase in lamina I neurons and to the synaptic transmission between nociceptive afferents and second order neurons in lamina I is not known. This has now been investigated in a lumbar spinal cord slice preparation from young Sprague,Dawley rats. Microfluorometric Ca2+ measurements with fura-2 have been used to analyse the Ca2+ increase in lamina I neurons after depolarization of the cells, resulting in a distinct and transient increase of the cytosolic Ca2+ concentration. This Ca2+ peak was reduced by the T-type channel blocker, Ni2+, by the L-type channel blockers, nifedipine and verapamil, and by the N-type channel blocker, ,-conotoxin GVIA. The P/Q-type channel antagonist, ,-agatoxin TK, had no effect on postsynaptic [Ca2+]i. The NMDA receptor channel blocker D-AP5 reduced the Ca2+ peak, whereas the AMPA receptor channel blocker CNQX had no effect. Postsynaptic currents, monosynaptically evoked by electrical stimulation of the attached dorsal roots with C-fibre and A,-fibre intensity, respectively, were reduced by N-type channel blocker ,-conotoxin GVIA and to a much lesser extent, by P/Q-type channel antagonist ,-agatoxin TK, and the L-type channel blockers verapamil, respectively. No difference was found between unidentified neurons and neurons projecting to the periaqueductal grey matter. This is the first quantitative description of the relative contribution of voltage-dependent Ca2+ channels to the synaptic transmission in lamina I of the spinal dorsal horn, which is essential in the processing of pain-related information in the central nervous system. [source] The expression of vesicular glutamate transporters VGLUT1 and VGLUT2 in neurochemically defined axonal populations in the rat spinal cord with emphasis on the dorsal hornEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2003A. J. Todd Abstract Two vesicular glutamate transporters, VGLUT1 and VGLUT2, have recently been identified, and it has been reported that they are expressed by largely nonoverlapping populations of glutamatergic neurons in the brain. We have used immunocytochemistry with antibodies against both transporters, together with markers for various populations of spinal neurons, in an attempt to identify glutamatergic interneurons in the dorsal horn of the mid-lumbar spinal cord of the rat. The great majority (94,100%) of nonprimary axonal boutons that contained somatostatin, substance P or neurotensin, as well as 85% of those that contained enkephalin, were VGLUT2-immunoreactive, which suggests that most dorsal horn neurons that synthesize these peptides are glutamatergic. In support of this, we found that most somatostatin- and enkephalin-containing boutons (including somatostatin-immunoreactive boutons that lacked calcitonin gene-related peptide and were therefore probably derived from local interneurons) formed synapses at which AMPA receptors were present. We also investigated VGLUT expression in central terminals of primary afferents. Myelinated afferents were identified with cholera toxin B subunit; most of those in lamina I were VGLUT2-immunoreactive, whereas all those in deeper laminae were VGLUT1-immunoreactive, and some (in laminae III,VI) appeared to contain both transporters. However, peptidergic primary afferents that contained substance P or somatostatin (most of which are unmyelinated), as well as nonpeptidergic C fibres (identified with Bandeiraea simplicifolia isolectin B4) showed low levels of VGLUT2-immunoreactivity, or were not immunoreactive with either VGLUT antibody. As all primary afferents are thought to be glutamatergic, this raises the possibility that unmyelinated afferents, most of which are nociceptors, express a different vesicular glutamate transporter. [source] Peripheral axotomy induces only very limited sprouting of coarse myelinated afferents into inner lamina II of rat spinal cordEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2002Lan Bao Abstract Peripheral axotomy-induced sprouting of thick myelinated afferents (A-fibers) from laminae III,IV into laminae I,II of the spinal cord is a well-established hypothesis for the structural basis of neuropathic pain. However, we show here that the cholera toxin B subunit (CTB), a neuronal tracer used to demonstrate the sprouting of A-fibers in several earlier studies, also labels unmyelinated afferents (C-fibers) in lamina II and thin myelinated afferents in lamina I, when applied after peripheral nerve transection. The lamina II afferents also contained vasoactive intestinal polypeptide and galanin, two neuropeptides mainly expressed in small dorsal root ganglion (DRG) neurons and C-fibers. In an attempt to label large DRG neurons and A-fibers selectively, CTB was applied four days before axotomy (pre-injury-labelling), and sprouting was monitored after axotomy. We found that only a small number of A-fibers sprouted into inner lamina II, a region normally innervated by C-fibers, but not into outer lamina II or lamina I. Such sprouts made synaptic contact with dendrites in inner lamina II. Neuropeptide Y (NPY) was found in these sprouts in inner lamina II, an area very rich in Y1 receptor-positive processes. These results suggest that axotomy-induced sprouting from deeper to superficial layers is much less pronounced than previously assumed, in fact it is only marginal. This limited reorganization involves large NPY immunoreactive DRG neurons sprouting into the Y1 receptor-rich inner lamina II. Even if quantitatively small, it cannot be excluded that this represents a functional circuitry involved in neuropathic pain. [source] Inhibition of scratching behaviour caused by contact dermatitis in histidine decarboxylase gene knockout miceEXPERIMENTAL DERMATOLOGY, Issue 3 2005M. Seike Abstract:, A neuronal system dedicated to itch consists of primary afferent and spinothalamic projection neurons. Histamine is thought to be one of the main mediators for the transmission of itch sensation. However, there are little available information on the role of histamine in scratching behaviour and sensory transmission of atopic dermatitis and chronic eczema. In the present study, the role of histamine in scratching behaviour and neural conduction of sensation in the chronic eczema model was investigated by using l-histidine decarboxylase (HDC) gene knockout mice lacking histamine. The chronic contact dermatitis was induced with daily application of diphenylcyclopropenone (DCP) on a hind paw of HDC (+/+) and HDC (,/,) mice for 2 months. The observation of scratching behaviour and the hot-plate test were performed in both mice. Histological studies were performed in the skin and spinal cord tissues. Histological examination revealed that both HDC (+/+) and HDC (,/,) mice displayed the similar extent of inflammatory cell infiltration, hyperplastic epidermis and newly spreading of neuronal processes in the skin tissue. Scratching behaviour was exclusively induced in HDC (+/+) mice, whereas it was barely observed in HDC (,/,) mice. The expression of c-Fos was specifically upregulated in HDC (+/+) mice in lamina I of the spinal dorsal horn following repeated DCP application. Scratching behaviour in chronic contact dermatitis in mice was thought mainly mediated with histamine. The afferent pathway of sensation in chronic contact dermatitis model may connect with the central nervous system through lamina I of the spinal dorsal horn. [source] Anatomy of Primary Afferents and Projection Neurones in the Rat Spinal Dorsal Horn with Particular Emphasis on Substance P and the Neurokinin 1 ReceptorEXPERIMENTAL PHYSIOLOGY, Issue 2 2002A. J. Todd The dorsal horn of the spinal cord plays an important role in transmitting information from nociceptive primary afferent neurones to the brain; however, our knowledge of its neuronal and synaptic organisation is still limited. Nociceptive afferents terminate mainly in laminae I and II and some of these contain substance P. Many projection neurones are located in lamina I and these send axons to various parts of the brain, including the caudal ventrolateral medulla (CVLM), parabrachial area, periaqueductal grey matter and thalamus. The neurokinin 1 (NK1) receptor on which substance P acts is expressed by certain neurones in the dorsal horn, including approximately 80% of lamina I projection neurones. There is also a population of large NK1 receptor-immunoreactive neurones with cell bodies in laminae III and IV which project to the CVLM and parabrachial area. It has been shown that the lamina III/IV NK1 receptor-immunoreactive projection neurones are densely and selectively innervated by substance P-containing primary afferent neurones, and there is evidence that these afferents also target lamina I projection neurones with the receptor. Both types of neurone are innervated by descending serotoninergic axons from the medullary raphe nuclei. The lamina III/IV neurones also receive numerous synapses from axons of local inhibitory interneurones which contain GABA and neuropeptide Y, and again this input shows some specificity since post-synaptic dorsal column neurones which also have cell bodies in laminae III and IV receive few contacts from neuropeptide Y-containing axons. These observations indicate that there are specific patterns of synaptic connectivity within the spinal dorsal horn. [source] Local axon collaterals of lamina I projection neurons in the spinal cord of young ratsTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 14 2010Peter Szucs Abstract Large, mediolaterally oriented neurons in lamina I of the spinal cord, frequently referred to as marginal cells of Waldeyer, are known to project to supraspinal targets via the anterolateral tract (ALT). Although dendritic organization of lamina I neurons has been extensively studied, little is known about their local axonal morphology and branching. With the help of oblique illumination, we visually identified large lamina I neurons in the isolated lumbar enlargement (L1,L6) of the spinal cord of P14,P20 rats. By using intracellular and cell-attached biocytin injections, we achieved extensive axonal and dendritic labeling in 77 lamina I cells, 40 of which were identified as ALT projection neurons. In the majority of the cases (n = 28), the main axon of these projection neurons gave rise to one or more thin collaterals on the ipsilateral side. Based on their trajectory and location, these collaterals could be divided into three major categories: dorsal, lateral, and ventral. Lamina I projection neurons had dorsal (n = 5), lateral (n = 8), or ventral (n = 6) collaterals only or a combination of these collateral types (n = 9). Our results suggest that lamina I ALT projection neurons can additionally function as local-circuit and propriospinal neurons participating in intra- and intersegmental spinal cord processing. J. Comp. Neurol. 518:2645,2665, 2010. © 2010 Wiley-Liss, Inc. [source] Neuronal disinhibition in the trigeminal nucleus caudalis in a model of chronic neuropathic painEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2010Yasmina B. Martin Abstract The mechanisms underlying neuropathic facial pain syndromes are incompletely understood. We used a unilateral chronic constriction injury of the rat infraorbital nerve (CCI-IoN) as a facial neuropathic model. Pain-related behavior of the CCI-IoN animals was tested at 8, 15 and 26 days after surgery (dps). The response threshold to mechanical stimulation with von Frey hairs on the injured side was reduced at 15 and 26 dps, indicating the presence of allodynia. We performed unitary recordings in the caudalis division of the spinal trigeminal nucleus (Sp5C) at 8 or 26 dps, and examined spontaneous activity and responses to mechanical and thermal stimulation of the vibrissal pad. Neurons were identified as wide dynamic range (WDR) or low-threshold mechanoreceptive (LTM) according to their response to tactile and/or noxious stimulation. Following CCI-IoN, WDR neurons, but not LTM neurons, increased their spontaneous activity at 8 and 26 dps, and both types of Sp5C neurons increased their responses to tactile stimuli. In addition, the on,off tactile response in neurons recorded after CCI-IoN was followed by afterdischarges that were not observed in control cases. Compared with controls, the response inhibition observed during paired-pulse stimulation was reduced after CCI-IoN. Immunohistochemical studies showed an overall decrease in GAD65 immunoreactivity in Sp5C at 26 dps, most marked in laminae I and II, suggesting that following CCI-IoN the inhibitory circuits in the sensory trigeminal nuclei are depressed. Consequently, our results strongly suggest that disinhibition of Sp5C neurons plays a relevant role in the appearance of allodynia after CCI-IoN. [source] Contribution of the Reelin signaling pathways to nociceptive processingEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2008Alin L. Akopians Abstract The reeler gene encodes Reelin, a secreted glycoprotein that binds to the very-low-density lipoprotein receptor (Vldlr) and apolipoprotein E receptor 2 (Apoer,2), and induces Src- and Fyn-mediated tyrosine phosphorylation of the intracellular adaptor protein Disabled-1 (Dab1). This Reelin,Dab1 signaling pathway regulates neuronal positioning during development. A second Reelin pathway acts through Apoer,2,exon 19 to modulate synaptic plasticity in adult mice. We recently reported positioning errors in reeler dorsal horn laminae I,II and V, and the lateral spinal nucleus. Behavioral correlates of these positioning errors include a decreased mechanical and increased thermal sensitivity in reeler mice. Here we examined mice with deletions or modifications of both the Reelin,Dab1 signaling pathway and the Reelin,Apoer,2,exon 19 pathway on a Vldlr-deficient background. We detected reeler -like dorsal horn positioning errors only in Dab1 mutant and Apoer,2/Vldlr double mutant mice. Although Dab1 mutants, like reeler, showed decreased mechanical and increased thermal sensitivity, neither the single Vldlr or Apoer,2 knockouts, nor the Apoer,2,exon 19 mutants differed in their acute pain sensitivity from controls. However, despite the dramatic alterations in acute ,pain' processing in reeler and Dab1 mutants, the exacerbation of pain processing after tissue injury (hindpaw carrageenan injection) was preserved. Finally, we recapitulated the reeler dorsal horn positioning errors by inhibiting Dab1 phosphorylation in organotypic cultures. We conclude that the Reelin,Dab1 pathway differentially contributes to acute and persistent pain, and that the plasticity associated with the Reelin,Apoer,2,exon 19 pathway is distinct from that which contributes to injury-induced enhancement of ,pain' processing. [source] Peripheral axotomy induces only very limited sprouting of coarse myelinated afferents into inner lamina II of rat spinal cordEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2002Lan Bao Abstract Peripheral axotomy-induced sprouting of thick myelinated afferents (A-fibers) from laminae III,IV into laminae I,II of the spinal cord is a well-established hypothesis for the structural basis of neuropathic pain. However, we show here that the cholera toxin B subunit (CTB), a neuronal tracer used to demonstrate the sprouting of A-fibers in several earlier studies, also labels unmyelinated afferents (C-fibers) in lamina II and thin myelinated afferents in lamina I, when applied after peripheral nerve transection. The lamina II afferents also contained vasoactive intestinal polypeptide and galanin, two neuropeptides mainly expressed in small dorsal root ganglion (DRG) neurons and C-fibers. In an attempt to label large DRG neurons and A-fibers selectively, CTB was applied four days before axotomy (pre-injury-labelling), and sprouting was monitored after axotomy. We found that only a small number of A-fibers sprouted into inner lamina II, a region normally innervated by C-fibers, but not into outer lamina II or lamina I. Such sprouts made synaptic contact with dendrites in inner lamina II. Neuropeptide Y (NPY) was found in these sprouts in inner lamina II, an area very rich in Y1 receptor-positive processes. These results suggest that axotomy-induced sprouting from deeper to superficial layers is much less pronounced than previously assumed, in fact it is only marginal. This limited reorganization involves large NPY immunoreactive DRG neurons sprouting into the Y1 receptor-rich inner lamina II. Even if quantitatively small, it cannot be excluded that this represents a functional circuitry involved in neuropathic pain. [source] Characterization of the single-channel properties of NMDA receptors in laminae I and II of the dorsal horn of neonatal rat spinal cordEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2001G. Mark Green Abstract The single-channel properties of native NMDA receptors in laminae I and II of the dorsal horn of the neonatal rat spinal cord were studied using outside-out patch-clamp techniques. These receptors were found to have several features that distinguish them from native NMDA receptors elsewhere in the CNS. Single-channel currents activated by NMDA (100 nm) and glycine (10 µm) exhibited five distinct amplitude components with slope-conductance values of 19.9 ± 0.8, 32.9 ± 0.6, 42.2 ± 1.1, 53.0 ± 1.0 and 68.7 ± 1.5 pS. Direct transitions were observed between all conductance levels but transitions between 69-pS openings and 20-, 33- and 42-pS openings were rare. There was no significant difference in the frequency of direct transitions from 42- to 20-pS compared to 20- to 42-pS transitions. The Kb (0 mV) for Mg2+ was 89 µm. The Mg2+ unblocking rate constant was similar to other reported values. However, the Mg2+ blocking rate constant was larger than other reported values, suggesting an unusually high sensitivity to Mg2+. The NR2B subunit-selective antagonist, ifenprodil, had no significant effect on overall channel activity but significantly decreased the mean open time of 53-pS openings. These results suggest neonatal laminae I and II NMDA receptors are not simply composed of NR1 and NR2B subunits or NR1 and NR2D subunits. It is possible that these properties are due to an as yet uninvestigated combination of two NR2 subunits with the NR1 subunit or a combination of NR3A, NR2 and NR1 subunits. [source] Anatomy of Primary Afferents and Projection Neurones in the Rat Spinal Dorsal Horn with Particular Emphasis on Substance P and the Neurokinin 1 ReceptorEXPERIMENTAL PHYSIOLOGY, Issue 2 2002A. J. Todd The dorsal horn of the spinal cord plays an important role in transmitting information from nociceptive primary afferent neurones to the brain; however, our knowledge of its neuronal and synaptic organisation is still limited. Nociceptive afferents terminate mainly in laminae I and II and some of these contain substance P. Many projection neurones are located in lamina I and these send axons to various parts of the brain, including the caudal ventrolateral medulla (CVLM), parabrachial area, periaqueductal grey matter and thalamus. The neurokinin 1 (NK1) receptor on which substance P acts is expressed by certain neurones in the dorsal horn, including approximately 80% of lamina I projection neurones. There is also a population of large NK1 receptor-immunoreactive neurones with cell bodies in laminae III and IV which project to the CVLM and parabrachial area. It has been shown that the lamina III/IV NK1 receptor-immunoreactive projection neurones are densely and selectively innervated by substance P-containing primary afferent neurones, and there is evidence that these afferents also target lamina I projection neurones with the receptor. Both types of neurone are innervated by descending serotoninergic axons from the medullary raphe nuclei. The lamina III/IV neurones also receive numerous synapses from axons of local inhibitory interneurones which contain GABA and neuropeptide Y, and again this input shows some specificity since post-synaptic dorsal column neurones which also have cell bodies in laminae III and IV receive few contacts from neuropeptide Y-containing axons. These observations indicate that there are specific patterns of synaptic connectivity within the spinal dorsal horn. [source] Comparison of Localization of the Neurokinin 1 Receptor and Nitric Oxide Synthase with Calbindin D Labelling in the Rat Spinal CordANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 3 2000M. Nazli Summary A comparison of the localization of the neurokinin 1 (NK1) receptor and nitric oxide synthase with calbindin D labelling in the lumbar spinal cord was carried out in the rat using immunocytochemistry. Considerable regional variations were observed. Application of the antibody to calbindin D resulted in dense staining in laminae I and II and light staining in the other laminae. Occasional scattered cells were seen in the deep laminae and in the lamina X, the ventral horn and the lateral spinal nucleus. The results indicate that neurones expressing calbindin D, NK1 receptor and NOS are three separate populations in the dorsal horn of the lumbar spinal cord. 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