Cell type and conduction velocity of rat primary sensory neurons with calcitonin gene-related peptide-like immunoreactivity

McCarthy, Peter W.; Lawson, Sally N.

doi:10.1016/0306-4522(90)90169-5

Cited by 228 publications

(116 citation statements)

References 31 publications

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“…[18][19][20] In uninjured spinal cord, CGRP immunopositive axons convey pain and temperature information, synapsing on second order neurons within lamina I and II of the spinal dorsal horns ( Figure 1). [21][22][23] These second order axons cross at the level of the spinal cord within the anterior spinal commissure and ascend through the spinothalamic tract to the thalamus. It has been shown that in animals with SCI, CGRP-containing fibers sprout into deeper laminas.…”

Section: Introductionmentioning

confidence: 99%

Calcitonin gene-related peptide immunoreactivity in chronic human spinal cord injury

2007

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Study Design: Histopathological study of the human spinal cord. Setting: International Collaboration on Repair Discoveries, Vancouver, BC, Canada. Rationale: In animals, primary dorsal root afferent fibers, which are immunoreactive for calcitonin gene-related peptide (CGRP), sprout following spinal cord injury (SCI) into deeper laminas of the dorsal horn below the level of injury. It has been suggested that this aberrant sprouting plays a role in altering cardiovascular control after SCI and could be responsible for life-threatening episodes of autonomic dysreflexia (AD). Objectives: To observe the changes of CGRP distribution after SCI and compare the differences between normal and injured human spinal cord. Methods: Upper thoracic segments from individuals with chronic cervical SCI (n ¼ 4) and individuals with intact spinal cords (n ¼ 5) were processed immunocytochemically to identify CGRP fibers and histologically to identify the severity of degeneration. Results: Semiquantitative analysis showed a significant increase in CGRP immunoreactivity in the dorsal horns of individuals with chronic SCI (Po0.001). Furthermore, one of the SCI individuals in this study displaying significant CGRP sprouting had well documented episodes of AD. Conclusions: Our observations suggest that SCI in humans results in significant sprouting of CGRP fibers. This aberrant sprouting of sensory fibers could contribute to the abnormal cardiovascular control and pain commonly observed following chronic human SCI.

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Section: Introductionmentioning

confidence: 99%

Calcitonin gene-related peptide immunoreactivity in chronic human spinal cord injury

2007

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“…In dorsal root ganglion (DRG), substance P and CGRP are synthesized predominantly in small B-cells, receiving signals through the peripheral C-and A␦-afferents (12,13). Because of the deficits of NGF support in experimental diabetes (14), it is expected that substance P and CGRP expressions are decreased.…”

Section: And P75mentioning

confidence: 99%

Selective Loss of Calcitonin Gene-Related Peptide-Expressing Primary Sensory Neurons of the A-Cell Phenotype in Early Experimental Diabetes

et al. 2004

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S ensory polyneuropathy develops insidiously in diabetes and involves all types of nerve fibers. Abnormal sensory perception in diabetic patients includes loss of pain and temperature sensations as well as burning and cutaneous hyperesthesia, typically in the feet and lower legs (1). The mechanisms underlying hypo-or hyperalgesia in diabetes are uncertain, but studies of diabetic rats indicate that unmyelinated afferents (2), myelinated afferents (3), and spinal and superspinal sensory neurons (4) are all involved in the process.Calcitonin gene-related peptide (CGRP) and substance P are nerve growth factor (NGF)-dependent neuropeptides (5,6). Increased expressions of CGRP and substance P in the peripheral nervous system relate to hyperalgesia or allodynia (7-9). Moreover, the CGRP-related hyperalgesia is abolished with a CGRP receptor antagonist (9), with an antiserum to CGRP (10), or by knockout of the CGRP gene (11).In dorsal root ganglion (DRG), substance P and CGRP are synthesized predominantly in small B-cells, receiving signals through the peripheral C-and A␦-afferents (12,13). Because of the deficits of NGF support in experimental diabetes (14), it is expected that substance P and CGRP expressions are decreased. Studies of substance P and CGRP content in rat sciatic nerve after 4 weeks of streptozotocin (STZ)-induced diabetes has confirmed this suggestion (15,16), whereas immunohistochemical studies indicate that the relative proportion of immunoreactive CGRP and substance P cells is unchanged in 4-week diabetic BB rats (17) and 12-month STZ-induced diabetic rats (18), despite dramatic reduction of CGRP and substance P mRNA in the DRG (5,14,18).The mechanical and nociceptive afferents could interact with each other through the interneurons at the spinal cord level. Touch-induced pain seems to involve incoming activity from low-threshold mechanoreceptors to large neuronal A-cells with subsequent presynaptic interaction with central nociceptive afferents in the dorsal horn of the spinal cord (19).We hypothesize that experimental diabetes is associated with an altered balance between the absolute numbers of large A-cells and small B-cells of CGRP-and substance P-expressing DRG neurons. Recently, we have shown that the low-affinity p75 neurotrophin receptor (p75 NTR ) influences the morphology of DRG cell bodies in STZ-induced diabetes, and, consequently, we hypothesize that the al-

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“…Entre 45 y 50% del total de neuronas del GRD de rata presenta inmunorreactividad para este péptido distribuida en todos los tamaños, pero con un mayor porcentaje en neuronas pequeñas (22,28).…”

Section: Neuropéptidosunclassified

“…de las neuronas Enzirnas positivas para CGRP (43-46%), 32% son graiides Tirosina kidrorilasa y RT97+, mientras que 68% son pequeñas, RT97-y tienen VC que van de 0,5 a 28 &seg, lo que sugiere que el impulso nervioso se conduce con fibras de todos los tipos (AaIP, AS y C en 33.46 y 17%, respectivaniente); esto concuerda con los datos de presencia de CGRP en neuronas de todos los tamaños aunque con cieria preferencia por las neuronas pequeñas (28,14).…”

Section: Neuropéptidosunclassified

Subpoblaciones neuronales presentes en el ganglio de la raíz dorsal

Martínez¹,

Quiroga²,

Castellanos³

et al. 2000

biomedica

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La función principal de las neuronas del ganglio de la raiz dorsal (GRD) es transmitir la información sensorial desde la periferia hasta el sistema nervioso central. Dos clases de células están presentes en el ganglio: las células no neuronales y las neuronales. La heterogeneidad morfológica, fisiológica y bioquimica de la población neuronal permite diferenciarla en subpoblaciones. Morfológicarnente, se distinguen tres tipos neuronales (A, B y C) segun el tamaño y las caracteristicas ultraestructurales. Fisiológicamente, hay una relación directa entre el tamaño, el diámetro de las fibras nerviosas y la velocidad con que conducen el impulso nervioso. Finalmente, el uso de marcadores (neuropéptidos, enzimas, receptores, etc.) permite realizar una clasificación bioquímica, que es la más utilizada para estudiar la función neuronal. Este articulo revisa la evidencia experimental sobre el tema de la heterogeneidad neuronal del GRD v wresenta una correlación desde el punto de vista bioauimico v fisiolóoico en -los casos en dondé'hay información disponible. El esiudio de subpoblaciones en este ganglio resulta de bastante interés para investigaciones en neurociencias, principalmente en infecciones por virus neurotrópicos, traurnatismos del nervio periférico y el estudio de factores neurotróficos, entre otros.Palabras clave: ganglio de la raiz dorsal, ganglio espinal, neuronas sensitivas, neurotransmisor, neurotrofina. Neuronal subpopulations present in t h e dorsal r o o t ganglionDorsal root ganglion (DRG) neurons main function is to convey sensory information from the periphery towards the central nervous system. Two kinds of cells are present in this ganglion: non-neurona1 cells and neurons. Morphological, functional and biochemical heterogeneity of the neuronal population makes it necessary to distinguish cellular subpopulations. There are three types of DRG neurons morphologically defined (A, B and C), according to their size and ultrastructural characteristics. There is a direct correlation behween cell size, diameter of the fibers and conduction velocity. Finally, a nurnber of markers such as neuropeptides, enzymes and receptors allow for a biochemical classification which is the most used for the study of the neuronal function. This paper reviews the experimental evidence on DRG neurons heterogeneity and presents a biochemical and physiological correlation in the cases when relevant information is available. Study of DRG neuron populations is relevant to different fields in neuroscience research. such as the study of neurotropic virus infection mechanisms, cellular and molecular biology of peripheral nerve injury and neurotrophic factors, among others.

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Cell type and conduction velocity of rat primary sensory neurons with calcitonin gene-related peptide-like immunoreactivity

Cited by 228 publications

References 31 publications

Calcitonin gene-related peptide immunoreactivity in chronic human spinal cord injury

Calcitonin gene-related peptide immunoreactivity in chronic human spinal cord injury

Selective Loss of Calcitonin Gene-Related Peptide-Expressing Primary Sensory Neurons of the A-Cell Phenotype in Early Experimental Diabetes

Subpoblaciones neuronales presentes en el ganglio de la raíz dorsal

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