Changes in PDGF expression in spared dorsal root ganglia and associated spinal dorsal horns in cats subjected to partial dorsal root ganglionectomy

Changes in the platelet derived growth factor (PDGF) in the spared dorsal root ganglia (DRG) and associated spinal dorsal horns were evaluated in cats subjected to unilateral removal of L1-L5 and L7-S2 DRG, sparing the L6 DRG. The number of PDGF immunopositive neurons and protein expression decreased significantly in the spared DRG and associated dorsal horns of the L3 and L6 cord segments at 3 days post-operation (dpo). It bottomed to the lowest level at 7 dpo in the DRG, then returned to the control level at 14 dpo; while in the L6 dorsal horn, it rapidly increased at 7 dpo and exceeded the control level at 14 dpo. This showed a significant upregulation in the spared DRG and associated spinal dorsal horns, especially in the L6 cord segment following a transient decrease. Meanwhile, a significant upregulation of PDGF mRNA was also seen in L6 DRG and L3 and L6 dorsal horns at 3 dpo. The upregulation of the endogenous PDGF in the said structures indicated a potential role of this factor in spinal cord plasticity after partial dorsal root ganglia removal in cats.     

Alteration of dorsal root ganglion P2X3 receptor expression and function following spinal nerve ligation in the rat

One subtype of ATP-gated ion channel, the P2X₃ receptor, is expressed primarily on peripheral sensory neurons. While it is known that P2X₃ receptors can participate in certain forms of nociceptive signaling, their involvement in neuropathic pain transmission is not known. We have examined the expression and function of P2X₃ receptors in a rat spinal nerve ligation model of neuropathic pain. Fourteen days following L5/L6 spinal nerve ligation, the corresponding dorsal root ganglia (DRG) were removed from animals exhibiting mechanical allodynia, and these were studied using immunohistochemical and electrophysiological techniques. Using a polyclonal antibody to label the P2X₃ receptor, a significant reduction in neuronal P2X₃ immunoreactivity was observed in the ipsilateral (injured) L5 and L6 DRG following nerve ligation. In vitro electrophysiological analysis of acutely isolated DRG neurons revealed a similar decrease in functional P2X₃-containing receptors. In small diameter (22–25 μm) neurons, a significant reduction in the number of cells exhibiting a response to α,β-meATP was observed. However, a subset of small diameter neurons retained P2X₃ responses of equal amplitude to those recorded from naive and sham control DRG neurons. Interestingly, P2X₃ immunoreactivity and P2X₃-like responses were also detected in a subset of larger diameter (50 μm) neurons and the number and amplitude of these responses were unchanged after spinal nerve ligation. These results suggest that, while there appears to be a decrease in fast desensitizing P2X₃ receptors following L5/L6 nerve ligation injury, certain subsets of small and large DRG neurons maintain normal P2X₃ receptor expression and function. These remaining receptors may provide a P2X₃ receptor-mediated component to neuropathic pain. Electronic Publication     

Expression patterns of erythropoietin and its receptor in the developing spinal cord and dorsal root ganglia

Recombinant human erythropoietin (EPO) is neuroprotective in animal models of adult spinal cord injury, and reduces apoptosis in adult dorsal root ganglia after spinal nerve crush. The present work demonstrates that spinal cord and dorsal root ganglia share dynamic expression patterns of EPO and its receptor (EPOR) during development. C57Bl mice from embryonic days (E) 8 (E8) to E19 were studied. In spinal cord and dorsal root ganglia, EPOR expression in all precursor cells preceded the expression of EPO in subsets of neurons. On E11, EPO-immunoreactive spinal motoneurons and ganglionic sensory neurons resided adjacent to EPOR-expressing radial glial cells and satellite cells, respectively. From E12 onwards, EPOR-immunoreactivity decreased in radial glial cells and, transiently, in satellite cells. Simultaneously, large-scale apoptosis of motoneurons and sensory neurons started, and subsets of neurons were labelled by antibodies against EPOR. Viable neurons expressed EPO and EPOR. Up to E12.5, apoptotic cells were EPOR-immunopositive, but variably EPO-immunonegative or EPO-immunopositive. Thereafter, EPO-immunonegative and EPOR-immunopositive apoptotic cells predominated. Our findings suggest that EPO-mediated neuron-glial and, later, neuron–neuronal interactions promote the differentiation and/or the survival of subsets of neurons and glial cells in central as well as in peripheral parts of the embryonic nervous system. Correspondingly, expression of phospho-Akt-1/protein-kinase B extensively overlapped expression sites of EPO and EPOR, but was absent from apoptotic cells. Identified other sites of EPO and/or EPOR expression include radial glial cells that transform to astrocytes, cells of the floor plate and notochord as well as neural crest-derived boundary cap cells at motor exit points and cells of the primary sympathetic chain.     

The immunocytochemical distribution of seven peptides in the spinal cord and dorsal root ganglia of horse and pig

Summary The distribution of calcitonin gene-related peptide (CGRP), enkephalin, galanin, neuropeptide Y (NPY), somatostatin, tachykinins and vasoactive intestinal polypeptide (VIP) was compared in cervical, thoracic, lumbar and sacral segmental levels of spinal cord and dorsal root ganglia of horse and pig.In both species, immunoreactivity for the peptides under study was observed at all segmental levels of the spinal cord. Peptide-immunoreactive fibres were generally concentrated in laminae I–III, the region around the central canal, and in the autonomic nuclei. A general increase in the number of immunoreactive nerve fibres was noted in the lumbosacral segments of the spinal cord, which was particularly exaggerated in the case of VIP immunoreactivity. In the horse, some CGRP-, somatostatin- or tachykinin-immunoreactive cell bodies were present in the dorsal horn. In the pig, cells immunoreactive for somatostatin, enkephalin or NPY were noted in a similar location.In the ventral horn most motoneurones were CGRP-immunoreactive in both species. However, in pig many other cell types were CGRP-immunoreactive not only in the ventral horn, but also in laminae V–VI of the dorsal horn.With the exception of enkephalin and NPY immunoreactivity, which was not seen in pig dorsal root ganglia, all peptides studied were localised to neuronal cell bodies and/or fibres in the dorsal root ganglia. In both species, immunolabelled cell bodies were observed in ganglia from cervical, thoracic, lumbar and sacral levels, with the exception of VIP-immunoreactive cells that were detected only in the lumbosacral ganglia. Numerous CGRP- and tachykinin-immunoreactive cell bodies were visualised in both species, while the cells immunolabelled with other peptide antisera were much lower in number.In both species, immunostaining of serial sections revealed that a subset of CGRP-immunoreactive cells co-expressed tachykinin, galanin or somatostatin immunoreactivity. In the horse some enkephalin-immunoreactive cells were also CGRP positive and occasionally combinations of three peptides, e.g. CGRP, tachykinin and galanin or CGRP, tachykinin and enkephalin were identified.The results obtained suggest that the overall pattern of distribution of peptide immunoreactivities is in general agreement with that so far described in other mammals, although some species variations have been observed, particularly regarding the presence of immunoreactive cell bodies in the dorsal horn of the spinal cord.     

Single-channel analysis of two types of Na+currents in rat dorsal root ganglia

The properties of voltage-gated Na⁺ channels were studied in neurones isolated from rat dorsal root ganglia using the outside-out configuration of the patch-clamp technique. Two types of single-channel currents were identified from the difference in unit amplitudes. Neither type was evoked in the medium in which extracellular Na⁺ ions were replaced by an equimolar amount of tetramethylammonium ions. The two types of single-channel currents differed in their sensitivity to tetrodotoxin (TTX). The smaller channel current was insensitive to 1 M TTX (referred to as TTX-I), while the larger channel current was blocked by 1 nM TTX (TTX-S). The unit amplitudes measured during a step depolarization to –30 mV (1.4 mM internal and 250 mM external Na⁺ concentrations) were 1.16 pA for TTX-S and 0.57 pA for TTX-I, respectively. The slope conductance measured at –30 mV was 16.3 pS for TTX-S and 8.5 pS for TTX-I. TTX-S could be activated by step depolarizations positive to –60 mV, while TTX-I could be activated at potentials positive to –40 mV. When the test pulse was preceded by a depolarizing prepulse, the prepulse positive to –50 mV preferentially inactivated TTX-S with a minimal effect on TTX-I. Activation and inactivation time courses of the averaged ensemble currents computed from TTX-S showed remarkable resemblances to the time courses of the macroscopic TTX-sensitive Na⁺ current. Similarly, the ensemble currents of TTX-I mimicked the macroscopic TTX-insensitive Na⁺ current. It was concluded that the two types of Na⁺ channels in rat dorsal root ganglia differ not only in their sensitivity to TTX, but also in their single-channel conductances.     

TNF-α在CCD模型大鼠背根神经节中的表达及机制

目的:探讨TNF-α和NF-κB在背根神经节慢性压迫(CCD)模型大鼠背根神经节(DRG)中的表达变化及其对疼痛学行为的影响。方法:建立CCD大鼠模型,采用von Frey纤维丝监测机械痛阈的改变;通过Western blotting检测TNF-α和NF-κB在DRG中的表达变化趋势,分析其与疼痛行为之间的相关性;并采用免疫荧光双染技术研究TNF-α在DRG中的表达位置。结果:CCD组的50%机械缩足阈值在术后1 d即开始明显下降(P0.01),7~14 d达到高峰,其后逐渐上升,直至术后35 d仍明显低于术前及sham组(P0.01)。而DRG上的TNF-α及NF-κB于造模后各时点均显著增多(P0.01),且TNF-α的表达趋势与50%机械缩足阈值显著相关(P0.05)。结论:DRG慢性压迫可促进其上的TNF-α和NF-κB的合成和分泌,进而诱发机械痛觉过敏。因此,TNF-α/NF-κB信号通路可能是CCD模型疼痛形成的重要通路之一。     

GABAB-mediated upregulation of the high-voltage-activated Ca2+ channels in rat dorsal root ganglia

 The mechanism underlying the enhancement of the high-voltage-activated (HVA) Ca²⁺ current (I _Ca) after application of baclofen, a GABA_B agonist, in neurones of the rat dorsal root ganglia was studied by a combined use of the nystatin perforated patch clamp recording and our rapid superfusion system. Baclofen (50 μM) decreased the peak amplitude of HVA I _Ca and slowed the onset of the current, i.e. produced a typical G-protein-mediated inhibition of I _Ca. However, when baclofen was rapidly removed from the medium, the amplitude of the current was rather augmented, exceeding the control value obtained before application of the drug. This enhancement was not due to a shift of the voltage dependence of Ca²⁺ channel activation or a change in ionic permeability to other ions. The enhancement of HVA I _Ca by baclofen was sensitive to pertussis toxin treatment. The enhancement was evident during superfusion of baclofen. Since the inhibitory effect of baclofen on HVA I _Ca was not attenuated, even after a continuous application of baclofen for 10 min, the enhancement was not due to relief from tonic G-protein-mediated inhibition of the current or a desensitization of the GABA_B receptor–effector system. An extremely prolonged time course of the enhancement of HVA I _Ca by baclofen strongly suggests an involvement of some intracellular signal transduction system. Received: 22 May 1996 / Received after revision: 17 October 1996 / Accepted: 7 January 1997     

Epidermal growth factor receptor in adult human dorsal root ganglia

Transforming growth factor- (TGF) enhances neuronal survival and neurite outgrowth in cultured dorsal root ganglia (DRG) sensory neurons. It binds a membrane protein, denominated epidermal growth factor receptor (EGFr). EGFr has been localized in developing and adult human DRG. However, it remains to be elucidated whether all DRG neurons express EGFr or whether differences exist among neuronal subtypes. This study was undertaken to investigate these topics in adult human DRG using immunoblotting, and combined immunohistochemistry and image analysis techniques. A mouse monoclonal antibody (clone F4) mapping within the intracytoplasmic domain of EGFr was used. Immunoblotting revealed two main proteins with estimated molecular masses of - 65 kDa and 170 kDa, and thus consistent with the full-length EGFr. Additional protein bands were also encountered. Light immunohistochemistry revealed specific immunoreactivity (IR) for EGFr-like proteins in most (86%) primary sensory neurons, the intensity of immunostaining being stronger in the small- and intermediate-sized ones. Furthermore, EGFr-like IR was also observed in the satellite glial cells of the ganglia as well as in the intraganglionic and dorsal root Schwann cells. Taken together, our findings demonstrate that EGFr, and other related proteins containing the epitope labeled with the antibody F4, are responsible for the EGFr IR reported in DRG. Furthermore, we demonstrated heterogeneity in the expression of EGFr-like IR in adult human primary sensory neurons, which suggests different responsiveness to their ligands.     

Localization of manserin,a secretogranin II-derived neuropeptide,in the oviduct of female rats

Gynecological disorders related to menstrual cycle may be affected by stress and can cause infertility. Manserin is a stress-related neuropeptide that is present in the neuroendocrine system. In the present study, we determined the localization of manserin in the oviduct of adult Wistar rats using immunohistochemical techniques. Manserin was detected on the surface of the epithelium of the oviduct, but not in the ovary and uterus. Localization of manserin was specific to a large portion of the isthmus and to a small portion of the ampulla. These results suggest that manserin localizes to secretory cells in the oviduct and may be involved in stress-induced gynecological disorders.     

大鼠背根神经节内kv2.1 mRNA和kv4.2 mRNA的表达

目的　了解kv2 1和kv4 2型钾离子通道在背根神经节的表达。方法　应用原位杂交方法观察背根神经节内细胞膜钾离子kv2 1和kv4 2型通道的mRNA阳性神经结构的表达。结果　腰 3～ 5背根神经节内均有kv2 1和kv4 2mRNA阳性神经元的表达 ,kv4 2mRNA阳性神经元的数量和总面积明显多于kv2 1阳性神经元。结论　kv2 1和kv4 2型钾离子通道可能参与了背根神经节对外周传入信息的传递和调制。     

Effects of nociceptin and analogues of nociceptin upon spontaneous dorsal root activity recorded from an in vitro preparation of rat spinal cord

The 17 amino acid peptide nociceptin has been implicated in pain modulation in the central nervous system. The effects of bath applied nociceptin, and some analogues of nociceptin, upon spontaneous lumbar dorsal root activity have been investigated in an isolated preparation of rat spinal cord. Nociceptin was found to reversibly depress spontaneous dorsal root activity at concentrations of 1.0 μM and 10.0 μM (IC₅₀ 2.0 μM), whereas acetyl-nociceptin at concentrations up to 10 μM had no detectable effect. Omission of the last four amino acids (nociceptin 1–13), increased the potency of the effect upon dorsal root activity by approximately 100-fold (IC₅₀ 30 nM), but activity was lost when only the first seven amino acids of the nociceptin molecule (nociceptin 1–7) were tested.     

Curcumin protects the dorsal root ganglion and sciatic nerve after crush in rat

The goal of this study was to quantify the histological changes in the dorsal root ganglion (DRG) and the sciatic nerve in rats subjected to sciatic nerve crush (SNC) following curcumin treatment. The rats were divided into four groups, each including five animals, and underwent the following intervention: group I: control animals which received olive oil; group II: sham-operated animals whose skin of the posterior thigh was opened, sutured, and received the vehicle; group III: SNC animals which received the vehicle; and group IV: SNC plus curcumin (100 mg/kg/day) solved in the vehicle. On the 28th day, the fifth lumbar DRG and sciatic nerve were removed. Volume of the ganglion, mean cell volume, total volume of DRG cells (A- and B-cells), and total surface of DRG cells, total number, diameter, and area of the myelinated nerve fibers were estimated using stereological methods. Except for the volume of the ganglion, all other parameters were decreased after nerve crush. In curcumin-treated rats, these parameters decreased, but to a lesser extent, and the values were significantly higher than in the non-treated SNC group (p < 0.04).It can be concluded that in rats after crush, curcumin has a protective effect on the DRG and sciatic nerve.     

Cell death after dorsal root injury

Flow cytometry and terminal deoxynucleotidyl transferase-mediated biotinylated uridine triphosphate nick end-labelling (TUNEL) immunohistochemistry have been used to assess cell death in the dorsal root ganglia (DRG) or spinal cord 1, 2 or 14 days after multiple lumbar dorsal root rhizotomy or dorsal root avulsion injury in adult rats. Neither injury induced significant cell death in the DRG compared to sham-operated or naïve animals at any time point. In the spinal cord, a significant increase in death was seen at 1–2 days, but not 14 days, post injury by both methods. TUNEL staining revealed that more apoptotic cells were present in the dorsal columns and dorsal horn of avulsion animals compared to rhizotomised animals. This suggests that avulsion injury, which can often partially damage the spinal cord, has more severe effects on cell survival than rhizotomy, a surgical lesion which does not affect the spinal cord. The location of TUNEL positive cells suggests that both neuronal and non-neuronal cells are dying.     

Comparison of two types of Na+ currents with low-voltage-activated T-type Ca2+ current in newborn rat dorsal root ganglia

Na⁺ currents and the low-voltage-activated T-type Ca²⁺ current (T-I _Ca) were recorded from neurons of rat dorsal root ganglia under similar ionic environments using the whole-cell patch-clamp technique. Two types of Na⁺ currents were identified on the basis of their sensitivity to tetrodotoxin (TTX) and channel kinetics. One type was blocked by 1 nM TTX and had a faster activation and inactivation time courses (F-I _Na), while the other type was insensitive to 100 M TTX and had a much slower channel kinetics (S-I _Na). Activation thresholds were –60, –40 and –70 mV for F-I _Na, S-I _Na and T-I _Ca, respectively. Peak amplitudes were obtained in respective current/voltage curves at –30 mV (F-I _Na), 0 mV (S-I _Na) and –50 mV (T-I _Ca). The time to peak and the decay time constant measured at potential levels giving peak amplitudes were 0.5 and 1.5ms for F-I _Na, 1.4 and 2.9 ms for S-I _Na and 8.1 and 17 ms for T-I _Ca, respectively. Cd²⁺ in a concentration of 50 M totally blocked T-I _Ca, whereas it had no effect on either type of Na⁺ current. T-I _Na was found in 18 out of 25 cells which possessed F-I _Ns, whereas it was found in only 2 cells among 15 which lacked F-I _Na. These three types of inward currents having different kinetic and pharmacological properties may mediate diverse functional roles in processing sensory signals.     

The effects of gallamine on field and dorsal root potentials produced by antidromic stimulation of motor fibres in the frog spinal cord

Summary The effects of gallamine on the intraspinal field potentials and the dorsal root potentials produced by antidromic stimulation of motor fibres were studied in the isolated frog spinal cord preparation. After gallamine (10^-3 M), the duration of the negative field potential produced by antidromic activation of motoneurons (N₁ response) was increased often without changing its amplitude. This resulted in an increased passive spread of the antidromic action potential towards the dorsal dendritic regions, where afferent fibres terminate.In the untreated spinal cord, stimulation of motor axons produced a late negative dorsal root potential (VR-DRP) which was depressed after gallamine administration. Abolition of the VR-DRP was frequently associated with the appearance of a short latency, conducted response, in the dorsal roots (EVR-DRP). The earliest component of the EVR-DRP had a latency ranging between 0.5 and 2.5 ms measured after the peak of the N₁ response recorded at the motor nucleus. Such a brief latency of the EVR-DRP suggests that this response results from electrical interaction between motoneurons and afferent fibres. After gallamine, the primary afferent depolarization produced by orthodromic stimulation of sensory nerves facilitates the EVR-DRP without necessarily increasing the amplitude or duration of the N₁ response. Also, gallamine appears to increase directly the excitability of the afferent fibre terminal arborizations.The nature of the electrical interaction between motoneuron dendrites and afferent fibre terminal arborizations is discussed in terms of two hypotheses: interaction by current flows and by electrical coupling.     

Monoclonal antibody 2C5: a marker for a subpopulation of small neurones in rat dorsal root ganglia

Monoclonal antibody 2C5 labels a subset of dorsal root ganglion neurones in the rat. The cell sizes of these neurones fall within the range for the small dark cell population and the antibody labels between a half and two-thirds of the neurones in this size range. A subpopulation of small neurones was also labelled in the trigeminal and vagal ganglia. Other sites of immunoreactivity in the central nervous system are the region of the substantia gelatinosa of the spinal cord, fibres in Lissauer's tract, the tractus solitarius and the tuberculum olfactorium. These sites are consistent with the antigen being expressed by the central processes of primary afferent neurones. It is suggested that the size distributions of 2C5-positive dorsal root ganglion neurones and the pattern of 2C5 immunoreactivity within the spinal cord indicate that the labelled cells may be neurones with peripheral C fibers. Outside the nervous system the antigen is expressed in a number of specific cell types within a variety of organs. These include some pancreatic acinar cells, parietal cells of the gastric mucosa, some cells in taste buds, Leydig cells of the testis, scattered cells in lymph nodes and lung alveoli, some renal tubules, the epithelial lining of the fallopian tube, the epithelium covering the ovary and certain cells in the basal layer of the epidermis.     

Ultrastructural cytochemical localization of carbonic anhydrase activity in rat peripheral sensory and motor nerves, dorsal root ganglia and dorsal column nuclei

Some of the myelinated axons in rat peripheral nerves possess marked axoplasmic carbonic anhydrase activity [Riley, Ellis and Bain (1982) J. Histochem. Cytochem. 30, 1275-1288; Riley and Lang (1984) J. Hand Surg. 9A, 112-120]. A mixture of reactive and nonreactive neurons was a general observation in cervical, thoracic and lumbar ganglia. Nonmyelinated axons in lumbar dorsal roots were nonreactive; this was consistent with the lack of carbonic anhydrase in small sensory neurons. The carbonic anhydrase cytochemical method marked the larger afferent or sensory neurons and distinguished them from the smaller sensory neurons which were devoid of carbonic anhydrase activity. Nonmyelinated axons in the lumbar ventral roots were also nonreactive. Examination of muscle spindle innervation revealed staining of the primary sensory and gamma motor endings. This was strongly suggestive that some of the reactive sensory neurons were primary afferents and a portion of the reactive ventral root axons were gamma motor. The reactive central processes of spinal neurons sent collaterals into the grey matter of the spinal cord, entered the dorsal funiculi, and terminated in synaptic glomeruli in the cuneate and gracilis nuclei. Oligodendroglial cells appeared to be the only intrinsic cellular elements of the brain stem and spinal cord that exhibited high carbonic anhydrase activity. Both oligodendroglial and Schwann cells exhibited intense carbonic anhydrase activity in thin pockets of cytoplasm internal to compact myelin. The subcellular distribution of reaction product within sensory neurons and oligodendroglial cells agreed with biochemical reports of cytosol and membrane-bound forms of carbonic anhydrase. A general staining of the cytoplasm was suggestive of soluble carbonic anhydrase fixed in situ by the glutaraldehyde. Clumps of reaction product on the cytoplasmic surface of the endoplasmic reticulum possibly represented membrane-bound enzyme. Most of the membrane-bound carbonic anhydrase was associated with the internal membranes rather than the axolemma or limiting plasma membrane of the axon. In contrast to biochemical reports, a small fraction of neuronal mitochondria exhibited staining in the intracristal spaces. We suggest that the association of carbonic anhydrase with endoplasmic reticulum and mitochondria implicates the enzyme in regulating intracellular calcium because both organelles are known to sequester calcium.     

The rostrocaudal organization in the dorsal root ganglia of the rat: a consequence of plexus formation?

The dorsal root ganglia (DRGs) of the rat have a rostrocaudal organization. This organization can most easily be demonstrated in fetal and neonatal rats because the spatial relationships of their DRGs are maintained better in tissue sections than those of mature rats. This review is concerned with the way in which the rostrocaudal organization of the DRGs is generated. Wheat germ agglutinin — horseradish peroxidase/horseradish peroxidase labeling of peripheral nerves of the brachial and lumbar plexuses shows that the position of the somata of the sensory neurons of the labeled nerves can be restricted to rostral or caudal halves of DRGs. Labeling of the thoracic nerve or its branches always results in labeling throughout the entire thoracic DRG. After application of the marker to forelimb nerves, it was observed that whenever a DRG is labeled only partially, its spinal nerve is correspondingly labeled partially as well. These data suggest that the rostrocaudal organization in the DRG is related to the formation of the plexuses. During development nerve fibers can be segmentally labeled, using the subdivision of the DRGs into a rostral and a caudal half to keep together as they find their way through the plexus. Application of label to forelimb skin, hindlimb skin and even thoracic skin can result in labeling of rostral or caudal halves of a DRG. A possible explanation might be that each dermatome can be divided into a skin area innervated by the rostral half of a DRG and a skin area innervated by the caudal half of the same dorsal root ganglion. In the rat, the segmental sensory innervation of muscles during development has not yet been investigated. The question of whether the segmental unit of innervation of a muscle is a whole DRG or half a DRG therefore still remains unanswered.     

体外原代培养小鼠胚胎背根神经节细胞的神经化学特征 

目的 探讨胚胎背根神经节（DRG）感觉神经元作为体外研究神经多肽的细胞模型之有效性。方法 采用免疫荧光及相差显微技术对30只胚胎小鼠背跟神经节细胞选择性神经多肽的分布、细胞大小及其多肽表达与细胞大小之间的关系进行观察比较。结果 培养时间达3周龄的DRG细胞主要以中小直径（30~20μm）的细胞为主,与成年在体脊髓DRG细胞的形态多形性特征类似;选择性神经多肽（钙调素基因相关多肽、P物质、甘丙肽和 nociceptin）的表达也随着体外培养时间的延长明显增强,且从早期仅在胞体部位表达到3周时细胞周围     

Gamma-aminobutiric acid immunostaining in trigeminal, nodose and spinal ganglia of the cat

Gamma-aminobutyric acid (GABA) is a principal inhibitory neurotransmitter in the vertebrate nervous system. It is found mainly in local circuit neurons, but it has also been described in sensory organs and dorsal root ganglia (DRG). The present study describes the presence of GABA in primary afferent neurons of feline sensory ganglia: trigeminal ganglia (TrG), nodose ganglia (NG), and DRG. Quantitative analysis revealed that approximately 20% of the cells in the TrG, NG and DRG are GABAergic. GABA-expressing neurons varied in size. GABA-containing neuronal fibres were also observed in the neuropil. Some of these were in close apposition to both GABA-positive and GABA-negative ganglionic neuronal perikarya. The localization of GABA in small primary afferent neurons, which are considered to be nociceptors, suggests that the amino acid may function as a pain transmitter or modulator, whereas processing of other sensory modalities, such as somatosensory and proprioceptive, may also be affected by GABA.