Mechanoreceptor signal convergence and transformation in the dorsal horn flexibly shape a diversity of outputs to the brain

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The Plasticity of the DRG Neurons Belonging to Different Subpopulations After Dorsal Rhizotomy

SUMMARY 1. The plasticity of sensory neurons following the injury to their axons is very important for prognosis of recovery of afferent fibers with different modality. It is evident that the response of dorsal root ganglion (DRG) neurons after peripheral axotomy is different depending on the deficiency in neurotrophic factors from peripheral region. The loss of cells appears earlier and is more severe in B-cells (small, dark cells with unmyelinated axons) than in A-cells (large, light cells with myelinated axons).2. We studied using immunohistochemical methods the response of DRG neurons to dorsal rhizotomy and combined injury of central and peripheral neuronal processes. A quantitative analysis of DRG neurons tagged by the selective markers isolectin B4 (IB4) and the heavy molecular component of the neurofilament triplet (NF200) antibody, selective for subpopulations of small and large/medium DRG neurons, respectively, was performed after dorsal rhizotomy, peripheral axotomy, and their combination.3. The number of NF200⁺-neurons is reduced substantially after both dorsal rhizotomy and peripheral axotomy, while the decrease of IB4⁺-neurons is observed only in combined injury, i.e., dorsal rhizotomy accompanied with sciatic nerve injury.4. Our results show that distinct subpopulations of DRG neurons respond differently to the injury of their central processes. The number of NF200⁺-neurons decreases to greater degree following dorsal rhizotomy in comparison to IB4⁺-neurons.     

Comparative internal structure of dorsal lips and radiolar appendages in sabellidae (Polychaeta) and phylogenetic implications

Fan worms (Sabellidae) possess paired modified prostomial structures at the base of the radiolar crown, dorso‐lateral to the mouth, called dorsal lips. The dorsal lips are involved in the sorting of particles collected by the radiolar crown. The range of variation in the morphology of dorsal lips is extensive, and probably this is not only due to adaptations to different environments and feeding preferences but also due to phylogenetic constraints. In this study, we describe and compare the morphology of dorsal lips in a range of sabellid taxa based on histological cross‐sections of these structures, and compare our data and terminology with those of previous studies. Dorsal lips are maintained erect in most taxa by a modified radiole fused to them known as dorsal radiolar appendage. We suggest that dorsal radiolar appendages with an internal supporting axis (cellular or acellular) and probably also the ventral lips are synapomorphies of the family. J. Morphol., 2011. © 2010 Wiley‐Liss, Inc.     

鸡胚脊髓背角中神经营养活性物质的初步分离和检测

从9d龄鸡胚脊髓背、腹角组织提取液中,用SephadexC-75凝胶层析法分离出DⅠ和DⅡ,VⅠ和VⅡ各组蛋白质组分,体外培养检测各组分对鸡胚背根节的神经营养活性,结果表明,DⅡ组分具有明显的促背根节神经突起生长的作用,而DⅠ组分无此作用;经SDS-PAGE电泳检测,DⅡ组分中蛋白质的分子量范围是61-15kD。而腹角的分离组分VⅠ和VⅡ对背根神经节神经突起的生长并无明显作用。     

The Effect of Nimodipine on Calcium Homeostasis and Pain Sensitivity in Diabetic Rats

Summary 1. The pathogenesis of diabetic neuropathy is a complex phenomenon, the mechanisms of which are not fully understood. Our previous studies have shown that the intracellular calcium signaling is impaired in primary and secondary nociceptive neurons in rats with streptozotocin (STZ)-induced diabetes. Here, we investigated the effect of prolonged treatment with the L-type calcium channel blocker nimodipine on diabetes-induced changes in neuronal calcium signaling and pain sensitivity.2. Diabetes was induced in young rats (21 p.d.) by a streptozotocin injection. After 3 weeks of diabetes development, the rats were treated with nimodipine for another 3 weeks. The effect of nimodipine treatment on calcium homeostasis in nociceptive dorsal root ganglion neurons (DRG) and substantia gelatinosa (SG) neurons of the spinal cord slices was examined with fluorescent imaging technique.3. Nimodipine treatment was not able to normalize elevated resting intracellular calcium ([Ca²⁺] _i ) levels in small DRG neurons. However, it was able to restore impaired Ca²⁺ release from the ER, induced by either activation of ryanodine receptors or by receptor-independent mechanism in both DRG and SG neurons.4. The beneficiary effects of nimodipine treatment on [Ca²⁺] _i signaling were paralleled with the reversal of diabetes-induced thermal hypoalgesia and normalization of the acute phase of the response to formalin injection. Nimodipine treatment was also able to shorten the duration of the tonic phase of formalin response to the control values.5. To separate vasodilating effect of nimodipine Biessels et al., (Brain Res. 1035:86–93) from its effect on neuronal Ca²⁺ channels, a group of STZ-diabetic rats was treated with vasodilator – enalapril. Enalapril treatment also have some beneficial effect on normalizing Ca²⁺ release from the ER, however, it was far less explicit than the normalizing effect of nimodipine. Effect of enalapril treatment on nociceptive behavioral responses was also much less pronounced. It partially reversed diabetes-induced thermal hypoalgesia, but did not change the characteristics of the response to formalin injection.6. The results of this study suggest that chronic nimodipine treatment may be effective in restoring diabetes-impaired neuronal calcium homeostasis as well as reduction of diabetes-induced thermal hypoalgesia and noxious stimuli responses. The nimodipine effect is mediated through a direct neuronal action combined with some vascular mechanism.     

Dorsal closure in Drosophila: cells cannot get out of the tight spot

Dorsal closure (DC), the closure of a hole in the dorsal epidermis of Drosophila embryos by the joining of opposing epithelial cell sheets, has been used as a model process to study the molecular and cellular mechanisms underlying epithelial spreading and wound healing. Recent studies have provided novel insights into how different tissues function cooperatively in this process. Specifically, they demonstrate a critical function of the epidermis surrounding the hole in modulating the behavior of the amnioserosa cells inside. These findings shed light not only on the mechanisms by which the behavior of different tissues is coordinated during DC, but also on the general mechanisms by which tissues interact to trigger global morphogenesis, an essential but yet poorly explored aspect of embryogenesis.     

Ontogeny and homology of the skeletal elements that form the sucking disc of remoras (Teleostei,Echeneoidei, Echeneidae)

The sucking disc of the sharksuckers of the family Echeneidae is one of the most remarkable and most highly modified skeletal structures among vertebrates. We studied the development of the sucking disc based on a series of larval, juvenile, and adult echeneids ranging from 9.3 mm to 175 mm standard length. We revisited the question of the homology of the different skeletal parts that form the disc using an ontogenetic approach. We compared the initial stages of development of the disc with early developmental stages of the spinous dorsal fin in a representative of the morphologically basal percomorph Morone. We demonstrate that the “interneural rays” of echeneids are homologous with the proximal‐middle radials of Morone and other teleosts and that the “intercalary bones” of sharksuckers are homologous with the distal radials of Morone and other teleosts. The “intercalary bones” or distal radials develop a pair of large wing‐like lateral extensions in echeneids, not present in this form in any other teleost. Finally the “pectinated lamellae” are homologous with the fin spines of Morone and other acanthomorphs. The main part of each pectinated lamella is formed by bilateral extensions of the base of the fin spine just above its proximal tip, each of which develops a row of spinous projections, or spinules, along its posterior margin. The number of rows and the number of spinules increase with size, and they become autogenous from the body of the lamellae. We also provide a historical review of previous studies on the homology of the echeneid sucking disc and demonstrate that the most recent hypotheses, published in 2002, 2005 and 2006, are erroneous. J. Morphol. 2012. © 2012 Wiley Periodicals, Inc.     

Calcium signaling in diabetic neuropathy

Diabetic neuropathy is a frequent complication of diabetes mellitus, for which no adequate clinical treatment is currently available. One of the main reasons for the absence of effective treatment of this disease is that information on how metabolic, vascular, and other abnormalities involved in the pathogenesis of diabetic neuropathy lead to dysfunction of nerve cells and pathways remains insufficient. Recent studies demonstrated that substantial abnormalities of calcium homeostasis in input neurons of the somatosensory nociceptive system are associated with many symptoms of diabetic neuropathy. Although proof of the causal linkage between calcium abnormalities and neuropathic complications is not conclusive, current research in neuroscience mostly indicates that such a linkage exists. Practically all known modifications of synaptic transmission in both central and peripheral nervous systems result from calcium-dependent modifications of the molecular players involved in this transmission. This is why the main goal of our review is to analyze in detail the fundamental cellular and molecular calcium-regulating mechanisms that are deteriorated in diabetes. As an important end-point of the proposed review, the capability of a widely used calcium channel blocker, nimodipine, to correct cytosolic and endoplasmic reticulum calcium abnormalities in neurons of the dorsal root ganglia and spinal dorsal horn and possible curative value of this agent in diabetic neuropathy are discussed.Neirofiziologiya/Neurophysiology, Vol. 36, No. 4, pp. 348–353, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Role of Calcium Signalling in the Development of Pain Syndromes

A comparative analysis of two models of nociceptive and neuropathic pain in rodents, carrageenan peripheral inflammation of soft tissues and streptozotocin-induced diabetic neuropathy, is presented in the review. Modern concepts on the pathways of transmission of pain information are analyzed. A few aspects of possible involvement at calcium signalling in neurons in the development of pain syndromes are discussed. Neirofiziologiya/Neurophysiology, Vol. 37, No. 2, pp. 184–190, March–April, 2005.     

Activin-like signal activates dorsal-specific maternal RNA between 8- and 16-cell stages of Xenopus

In many animals the dorsalventral axis forms by an initial localization of maternal molecules, which then regulate the spatial location of signals that directly influence the expression of axis-specific fates. Several recent studies have demonstrated that dorsal-animal blastomeres of the Xenopus morula (8–32 cells) are biased toward dorsal fates prior to mesoderm inductive signaling In this study we ask whether the dorsal bias is the result of autonomous expression of maternal molecules specifically localized within dorsal cells or of early activating signals. It was found that although 16-cell dorsal-animal blastomeres (D1.1) can differentiate into dorsal tissues when cultured alone, the 8-cell mothers (D1) can not. Likewise, although RNA extracted from D1.1 can induce an extra dorsal axis when injected into vegetal blastomeres, RNA extracted from D1 can not. However, D1 does express dorsal tissues if co-cultured with dorsal-vegetal cells or with culture medium containing a mixture of activins (PIF-medium). Furthermore, short-term culture of D1 in PIF-medium enables the D1 RNA to induce an ectopic dorsal axis. Ven ral-animal blastomeres also can express dorsal axial tissues when co-cultured with dorsal-vegetal blastomeres or in PIF-medium, but the RNA from the activin-treated ventral cells cannot induce ectopic dorsal axes. These studies demonstrate that there are maternal RNAs that, shortly after fertilization are present only in the dorsalanimal region. They do not act cell autonomously, but require an activin-like signal. These RNAs may function by increasing the responsiveness of dorsal-animal blastomeres to the mesoderm inductive signals present in both the morula and the blastula. © Wiley-Liss, Inc.     

蟾蜍离体脊神经节神经元对其外周突与中枢突重复刺激的反应

本工作用细胞内记录技术记录了18个蟾蜍离体背根节神经元对其外周突与中枢突刺激的反应。1-2Hz刺激背根和坐骨神经引起的背根节细胞的动作电位参数相同。随着刺激频率增高,30％的细胞对背根和坐骨神经刺激同步地发生动作电位振幅降低、波形分解和脱失;70％的细胞也产生不同程度的变化。背根节细胞对背根和坐骨神经重复刺激不能跟随的频率分别平均为126 Hz和323Hz。结果表明,本工作所记录的背根节细胞为A型神经元,其中枢突的直径小于外周突。对上述变化的可能机制,文中也做了讨论。     

Apical surface ring formation in Cyprinus carpio scale epidermis

Apical Rings (ARs) are novel circular structures located at the apical surface of fish scale epidermal cells. Different stages in the life cycle of ARs were established using time-lapse video microscopy of Koi scale epidermis in situ. The organization of the F-actin cytoskeleton corresponding to the stages of ring formation in live tissue was determined from phalloidin staining of scale epidermis. ARs form from localized swollen regions of microridges that subsequently elongate laterally, progressing into complete circles with well-defined inner and outer borders that encircle unperturbed microridges. The ARs close in a centripetal movement to form a circular structure, the terminal disc, and subsequently an underlying vesicle, the terminal body. During this latter stage, a rapid rearrangement of the actin cytoskeleton occurs resulting in the emergence of a newly identified corkscrew-like structure, termed the Helical Core. Furthermore, fluid-phase markers are incorporated into the terminal bodies, identifying these vesicles as macropinosomes. The findings are discussed with respect to F-actin organization and macropinocytosis at the epidermal surface of fish.     

Promotion of Remyelination by Sulfasalazine in a Transgenic Zebrafish Model of Demyelination

Most of the axons in the vertebrate nervous system are surrounded by a lipid-rich membrane called myelin, which promotes rapid conduction of nerve impulses and protects the axon from being damaged. Multiple sclerosis (MS) is a chronic demyelinating disease of the CNS characterized by infiltration of immune cells and progressive damage to myelin and axons. One potential way to treat MS is to enhance the endogenous remyelination process, but at present there are no available treatments to promote remyelination in patients with demyelinating diseases.Sulfasalazine is an anti-inflammatory and immune-modulating drug that is used in rheumatology and inflammatory bowel disease. Its anti-inflammatory and immunomodulatory properties prompted us to test the ability of sulfasalazine to promote remyelination. In this study, we found that sulfasalazine promotes remyelination in the CNS of a transgenic zebrafish model of NTR/MTZ-induced demyelination. We also found that sulfasalazine treatment reduced the number of macrophages/microglia in the CNS of demyelinated zebrafish larvae, suggesting that the acceleration of remyelination is mediated by the immunomodulatory function of sulfasalazine. Our data suggest that temporal modulation of the immune response by sulfasalazine can be used to overcome MS by enhancing myelin repair and remyelination in the CNS.     

A specimen of Salmo trutta (Pisces: Salmonidae) possessing an additional dorsal fin

A specimen of brown trout, Salmo trutta , with a supernumerary dorsal fin located just posterior to the nape is documented from the Yarra River, Victoria, Australia.     

Dynamic apical surface rings in superficial layer cells of koi Cyprinus carpio scale epidermis

This study examined the novel ring‐shaped structures found in the apical surface of individual cells of the scale epidermis of koi Cyprinus carpio. These apical rings are highly dynamic structures with lifetimes ranging from a few to several minutes. While several ring forms were observed, the predominant ring morphology is circular or oval. Two distinct ring forms were identified and designated type I and type II. Type I rings have a well‐defined outer border that encircles the surface microridges. Type II rings are smooth‐surfaced, dinner‐plate‐like structures with membranous folds or compressed microridges in the centre. Type II rings appear less frequently than type I rings. Type I rings form spontaneously, arising from swollen or physically interrupted microridges but without initially perturbing the encircled microridges. After persisting for up to several minutes the ring closes in a centripetal movement to form a circular or irregular‐shaped structure, the terminal disc. The terminal disc eventually disappears, leaving behind a submembranous vesicle‐like structure, the terminal body. Type I rings can undergo multiple cycles of formation and closing. Recycling epidermal apical rings form through centrifugal expansion from the terminal disc followed by apparent contraction back to the disc structure, whereupon the cycle may repeat or cease. The findings demonstrate a novel skin surface structure in fishes and are discussed with respect to communication with the external aqueous environment.