Showing papers on "Nervous system published in 1985"

The rat nervous system

Abstract: Vasculature O.U. Scremin, Cerebral Vascular System. Spinal Cord and Peripheral Nervous System C. Molander and G. Grant, Spinal Cord Cytoarchitecture. A. Ribeiro-da-Silva, Substantia Gelantinosa of Spinal Cord. G. Grant, Primary Afferent Projections to the Spinal Cord. D.J. Tracey, Ascending and Descending Pathways in the Spinal Cord. G. Gabella, Autonomic Nervous System. Brainstem and Cerebellum C.B. Saper, CentralAutonomic System. G. Holstege, The Basic, Somatic, and Emotional Components of the Motor System in Mammals. B.E. Jones, Reticular Formation: Cytoarchitecture, Transmitters, and Projections. A.J. Beitz, Periaqueductal Gray. G. Aston-Jones, M.T. Shipley, and R. Grzanna, The Locus Coeruleus, A5 and A7 Noradrenergic Cell Groups. J.H. Fallon and S.E. Loughlin, Substantia Nigra. J.B. Travers, Oromotor Nuclei. G. Holstege, B.F.M. Blok, and G.J. ter Horst, Brain Stem Systems Involved in the Blink Reflex, Feeding Mechanisms, and Micturition. T.J.H. Ruigrok and F. Cella, Precerebellar Nuclei and Red Nucleus. J. Voogd, Cerebellum. Forebrain R.B. Simerly, Anatomical Substrates of Hypothalamic Integration. W.E. Armstrong, Hypothalamic Supraoptic and Paraventricular Nuclei. B.J. Oldfield and M.J. McKinley, Circumventricular Organs. R.L. Jakab and C. Leranth, Septum. D.G. Amaral and M.P. Witter, Hippocampal Formation. G.F. Alheid, J.S. de Olmos, and C.A. Beltramino, Amygdala and Extended Amygdala. L. Heimer, D.S. Zahm, and G.F. Alheid, Basal Ganglia. J.L. Price, Thalamus. K. Zilles and A. Wree, Cortex: Areal and Laminar Structure. Sensory Systems D.J. Tracey and P.M.E. Waite, Somatosensory System. P.M.E. Waite and D.J. Tracey, Trigeminal Sensory System. W.D. Willis, K.N. Westlund, and S.M. Carlton, Pain. R. Norgren, Gustatory System. J.A. Rubertone, W.R. Mehler, and J. Voogd, The Vestibular Nuclear Complex. W.R. Webster, Auditory System. A.J. Sefton and B. Dreher, Visual System. M.T. Shipley, J.H. McLean, and M. Ennis, Olfactory System. Neurotransmitters G. Halliday, A. Harding, and G. Paxinos, Serotonin and Tachykinin Systems. S.E. Loughlin, F.M. Leslie, and J.H. Fallon, Endogenous Opioid Systems. L.L. Butcher, Cholinergic Neurons and Networks. O.P. Ottersen, O.P. Hjelle, K.K. Osen, and J.H. Laake, Amino Acid Transmitters. Development S.A. Bayer and J. Altman, Neurogenesis and Neuronal Migration. S.A. Bayer and J. Altman, Principles of Neurogenesis, Neuronal Migration, and Neural Circuit Formation. Subject Index.

Identification of major cell classes in the developing mammalian nervous system

Abstract: A major difficulty in studying early developmental processes and testing hypotheses of possible cellular mechanisms of development has been the inability to reproducibly identify specific cell types. We have generated monoclonal antibodies that distinguish among major cell types present during mammalian neurogenesis. These antibodies have been used to analyze the development of cellular organization in the early nervous system. Monoclonal antibody Rat-401 identifies a transient radial glial cell in the embryonic rat central nervous system (CNS) that is temporally and spatially suited to guide neuronal migration. Rat-401 also identifies a peripheral non-neuronal cell that may establish axon routes from the CNS to the periphery. Monoclonal antibody Rat-202 recognizes an antigen present in early axons, their growth cones, and filopodia, and has allowed us to follow early axons and observe the structures they contact. Two other antibodies that recognize axons demonstrate antigenically distinct phases in axon development. In addition, we report a marker for another cell class present in the developing nervous system, the endothelial cells that give rise to the CNS vasculature.

Limits of neurogenesis in primates.

Abstract: Systematic analysis of autoradiograms prepared from postpubertal rhesus monkeys given single and multiple injections of tritium-labeled thymidine and killed 3 days to 6 years later displayed a slow turnover of glial cells but failed to reveal any radiolabeled neurons. Therefore, unlike neurons of some nonprimate species, all neurons of the rhesus monkey brain are generated during prenatal and early postnatal life. A stable population of neurons in primates, including humans, may be important for the continuity of learning and memory over a lifetime.

Calcitonin gene-related peptide and its binding sites in the human central nervous system and pituitary.

Abstract: Binding sites for synthetic human 125I-labeled calcitonin gene-related peptide (125I-CGRP) have been demonstrated in membranes of the human nervous system. Binding was high in the cerebellar cortex (1.35 +/- 0.27 fmol/mg of tissue; mean +/- SEM), spinal cord (1.06 +/- 0.27 to 1.27 +/- 0.23 fmol/mg), and nucleus dentatus (1.02 +/- 0.15 fmol/mg), intermediate in the inferior colliculus (0.80 +/- 0.14 fmol/mg) and substantia nigra (0.75 +/- 0.14 fmol/mg), low in the neocortex, globus pallidus, nucleus caudatus, hippocampus, amygdala, superior colliculus, thalamus, and hypothalamus (0.15-0.32 fmol/mg), and negligible in spinal and sympathetic ganglia and pituitary (less than 0.04 fmol/mg). Autoradiography showed distinct 125I-CGRP binding over the molecular and Purkinje cell layers of the cerebellar cortex and over the substantia gelatinosa posterior of the spinal cord. The highest levels of CGRP-like components were recognized in the dorsal part of the spinal cord and the pituitary gland. In the ventral part of the spinal cord as well as in the pituitary and thyroid glands, CGRP values were higher when measured by radioreceptorassay as compared to RIA, indicating that at least two CGRP-like components are present. The predominant CGRP-like peak on HPLC had the retention time of synthetic human CGRP. Immunohistochemistry revealed the presence of a dense plexus of CGRP immunoreactive nerve fibers in the dorsal horn of the spinal cord.

Neurobiology of Arachnids

Abstract: A The Central Nervous System: Structure and Development.- I Patterns of Arrangement and Connectivity in the Central Nervous System of Arachnids.- II Ontogeny of the Arachnid Central Nervous System.- III The Stomatogastric Nervous System and Neurosecretion.- B Structure and Function of Sensory Systems.- Vision.- IV The Morphology and Optics of Spider Eyes.- V The Fine Structure of Spider Photoreceptors in Relation to Function.- VI Photoreceptor Cells in the Spider Eye: Spectral Sensitivity and Efferent Control.- Mechano- and Chemoreception.- VII Mechano- and Chemoreceptive Sensilla.- VIII Trichobothria.- IX Slit Sensilla and the Measurement of Cuticular Strains.- Sensory Nerves and Peripheral Synapses.- X Sensory Nerves and Peripheral Synapses.- C Senses and Behavior.- XI Neuroethology of the Spider Vibration Sense.- XII Spider Proprioception: Receptors, Reflexes, and Control of Locomotion.- XIII Target Discrimination in Jumping Spiders (Araneae: Salticidae).- XIV Homing Behavior and Orientation in the Funnel-Web Spider, Agelena labyrinthica Clerck.- XV Analytical Cybernetics of Spider Navigation.- D The Motor System.- XVI Neural Control of the Heartbeat and Skeletal Muscle in Spiders and Scorpions.- XVII Central and Peripheral Organization of Scorpion Locomotion.- E Neurobiology of a Biological Clock.- XVIII Neurobiology of a Circadian Clock in the Visual System of Scorpions.

Distribution of Ultrabithorax proteins in Drosophila.

Abstract: We have used a monoclonal antibody to examine the distribution of Ultrabithorax (Ubx) proteins in Drosophila embryos and imaginal discs by immunofluorescence. Ubx proteins are nuclear and show a spatially restricted distribution in the nervous system, epidermis and mesoderm. Labelling extends from the first thoracic segment (T1) to the eighth abdominal segment (A8) in the midline cells, from T2 to A8 in the ventral nervous system and epidermis and from A1 to A8 in the somatic mesoderm. In the nervous systems and epidermis the patterns of labelling exhibit a repeat unit, the Ubx metamere, that is out of phase with the segmental repeat unit. At least in the epidermis this repeat unit appears to extend between anterior-posterior compartment boundaries and consists of a posterior compartment together with the succeeding anterior compartment. The most prominently labelled metamere in the nervous system and epidermis is that comprising the posterior region of T3 and the anterior region of A1. Within each metamere the nuclei are heterogeneously labelled. Clear heterogeneity of labelling is also seen amongst the nuclei of the T3 imaginal discs.

Polyneuropathy and IgM monoclonal gammopathy: Studies on the pathogenetic role of anti‐myelin‐associated glycoprotein antibody

Abstract: Attention has recently been directed toward patients having a polyneuropathy and a monoclonal IgM anti-myelin-associated glycoprotein (anti-MAG) antibody. The possibility of a pathogenetic role for the anti-MAG antibody in the evolution of the polyneuropathy and in the development of central nervous system signs, including tremor and ataxia, remains unresolved. In 5 patients with this syndrome whose clinical courses were followed closely, in 1 of whom a complete postmortem examination of the nervous system was performed, we made the following observations: the anti-MAG antibody did not localize to the compact layer of the myelin sheath in affected nerves, but did localize to areas of myelin splitting; anti-MAG antibody present in the sural nerve of an affected individual for 7 years was not associated with progressive pathology; anti-MAG antibody was not deposited in the central nervous system of an affected individual, although the antibody did bind to these same tissues in vitro; deposition of anti-MAG antibody observed at postmortem examination did not correlate with the degree of pathological change; and study of the peripheral nervous system favored a primary axonal neuropathy with secondary demyelination.

Culture and characteristics of hormone-responsive neuroblastoma X glioma hybrid cells.

Abstract: Publisher Summary Due to the complexity of the mammalian nervous system, results from biochemical or pharmacological experiments with pieces or homogenates of nervous tissue are difficult to interpret. Only recently, a few cases have been reported of apparently relatively homogeneous populations of certain cell types from nervous tissue. This chapter studies molecular mechanisms of nervous tissue functions that have been resting completely on model systems derived from tumors of the nervous system and describes the methodology for handling tumor cell lines of neuronal character. By somatic cell hybridization, several hybrid cell lines have been generated from mouse neuroblastoma and rat glioma cells, some of which display a long list of neuronal properties and in which these differentiated functions are well expressed. Therefore, these cells are especially suited for studying such functions among which are susceptibilities to peptide hormones.

Neuronal cholecystokinin: one or multiple transmitters?

Abstract: The discovery of large amounts of regulatory peptides in the brain over the last decade is an important milestone in neurobiology. Neuropeptides are no longer considered a small group of hypothalamic substances regulating the secretion of pituitary hormones. Neuropeptides are potent transmitters in all parts of the central and peripheral nervous systems. Sometimes the peptides coexist and operate synergistically with the so-called classic transmitters (monoamines, acetylcholine, and amino acids) in acute synaptic transmissions. Possibly, neuropeptides are involved also in functions such as control of neuronal growth and metabolism (for recent general reviews, see Krieger, 1983; Krieger et al., 1984). Among the neuropeptide systems known today perhaps the largest group are hormones synthesized also in endocrine cells of the gastrointestinal tract and the pancreas. Thus, when they were found in the brain, methods for analysis were already at hand for some of these peptides-a fact that has advanced the study of the brain-gut peptides considerably. Although most of gut peptides occur only in discrete brain areas and/or in limited amounts (for instance, secretin, gastrin, insulin, glucagon, and motilin) others are distributed to most regions of the central and peripheral nervous systems [e.g., cholecystokinin (CCK), somatostatin, and vasoactive intestinal polypeptide (VIP)]. The CCK peptides, however, hold a unique position among brain peptides-including those originally isolated from brain tissue (substance P and other tachykinins, neurotensin, enkephalins, and others). First, the total amount of CCK in the mammalian CNS is higher than that of any other known regulatory peptide; and second, the distribution is unique, with the highest CCK concentrations in the cerebral cortex (Rehfeld, 197th; Larsson and Rehfeld, 1979a: Lamers et al., 1980; Beinfeld et al., 1981; Marley et al., 1984). The amounts and concentrations in the brain are significantly above also those of the recently discovered neuropeptide Y (Tatemot0 et al., 1982; Tatemoto, 1982), which by some has been claimed to be the most abundant peptide in mammalian brain (Allen et al., 1983; Adrian et al., 1983). In addition, CCK has aroused specific interest in schizophrenia research, because of its coexistence with 3,4-dihydroxyphenylethylarnine (dopamine) in the crucial mesolimbic neurons (Hokfelt et al., 1980a, 6) . The great interest in neuronal CCK has been emphasized by two recent international symposia devoted exclusively to brain CCK. Interested readers are referred to the proceedings from these meetings (de Belleroche and Dockray, 1984; Crawley and Vanderhaeghen, 1985). In spite of the substantial interest, fundamental questions about neuronal CCK are still unanswered, as reflected in the often confusing literature on CCK. The problem is not least attributable to ignorance of the extensive molecular heterogeneity of CCK. Therefore this review addresses the heterogeneity in terms of structure and biosynthesis of the different CCK molecules in the nervous system. In other words, is neuronal CCK a system comprising different neurotransmitters rather than one‘? As a starting point for neurochemists unfamiliar with gut endocrinology, a summary of the long history of intestinal CCK may give some perspective.

Pathways of the early propagation of virulent and avirulent rabies strains from the eye to the brain.

Abstract: Penetration of the central nervous system of the adult rat by the CVS strain of rabies virus and its two avirulent derivatives Av01 and Av02 has been studied by inoculation of the virus into the anterior chamber of the eye. The primary sites of penetration of CVS were (i) the intraocular parasympathetic oculomotor fibers, (ii) the retinopetal fibers of pretectal origin, and (iii) the intraocular fibers of the ophthalmic nerve. The mutant strains, however, lost the capacity to invade the two former groups of fibers, although their penetration into the trigeminal system was not impaired. Neither strain CVS nor the mutants infected primarily the intraocular adrenergic terminals and the optic nerve. Mutant strains, but not CVS, were able to infect the lens. These results indicate that the cholinergic receptor may not be the only receptor for rabies virus and that rabies virus is conveyed in the nervous system by retrograde axoplasmic flow. Strain CVS spread throughout the brain and propagated eventually back to the retina. The mutants penetrated the brain as well, but the infection was slow, involved different cerebral structures, and cleared up completely in 3 weeks, probably because of an efficient immune response.

N-Acetylation of L-aspartate in the nervous system: differential distribution of a specific enzyme

Abstract: L-Aspartate N-acetyltransferase, a nervous system enzyme that mediates the synthesis of N-acetyl-L-aspartic acid, has been characterized. In the presence of acetyl-CoA, L-aspartate was acetylated 10-fold more efficiently than L-glutamate, and the acetylation of aspartylglutamate was not detectable. Within the nervous system, a 10-fold variation in the enzyme activity was observed, with the brainstem and spinal cord exhibiting the highest activity (10-15 pmol/min/mg tissue) and retina the lowest detectable activity (1-1.5 pmol/min/mg). No enzyme activity was detected in pituitary, heart, liver, or kidney. The enzyme activity was found to be membrane-associated and was solubilized by treatment with Triton X-100.

The intrinsic vasculature of the lumbosacral spinal nerve roots

Abstract: The observations made in this study strongly support the concept that spinal nerve roots in general and the human lumbosacral spinal nerve roots in particular are structurally, vascularly, and metabolically unique regions of the nervous system. Peculiarities of their intrinsic vasculature and supporting connective tissue may account for suspected "neuroischemic" responses to pathologic mechanical stresses and inflammatory conditions associated with degenerative disease of the lower spine. It is hoped that the newly described features of the radicular vasa nervorum (to avoid confusion with the dissimilar blood supply of peripheral nerves, the term "vasa radiculorum" might be more accurate) may advance the understanding of certain aspects of lower spine symptomatology and provide some basis for much needed future research.

Organic solvent neurotoxicity. Facts and research needs.

Abstract: While many organic solvents are, in large doses, capable of inducing an acute, reversible narcotic state, few unequivocally induce chronic, long-lasting, or irreversible changes in nervous system structure and/or function. For organic solvents with proved neurotoxic properties, the type of neurological damage is closely related to the structure of the chemical agent, while the degree of impairment and the extent of reversibility are related to the potency, dose, and duration of exposure. Examples include solvents containing n-hexane or methyl n-butyl ketone, which have caused many cases of occupational neuropathy. Chronic inhalation abuse of pure toluene produces irreversible cerebellar, brainstem, and pyramidal-tract dysfunction, but comparable changes have not been found in solvent workers occupationally exposed to toluene. Ototoxicity is found in experimental animals exposed to toluene, xylene, or styrene. Impure trichloroethylene has a predilection for damaging the trigeminal nerve; dichloroacetylene, a breakdown product of trichloroethylene, is probably responsible for this neurotoxic property. Prolonged occupational exposure to mixed solvents, notably white spirit, has been reported to induce a mild, nonprogressive dementing illness with or without peripheral nerve dysfunction, but supporting data from neuropathological and experimental animal studies are lacking. Many other solvents have been reported to induce adverse effects in workers. The pivotal biological role of the nervous system and its vulnerability to selected organic solvents widely used in industry underline the urgent need for further clinical and experimental research on this problem.

Changes in the dendritic branching of adult mammalian neurones revealed by repeated imaging in situ.

Abstract: A major obstacle to understanding the mechanism of long-term change in the vertebrate nervous system has been the inability to observe the same nerve cell at different times during the life of an animal. The possibility that changes in neural connectivity underlie the remarkable flexibility of the nervous systems of mammals has therefore not been tested by direct observation. Here, we report studies in which we have visualized the same neurone in the superior cervical ganglion of young adult mice at intervals of up to 33 days. This collection of nerve cells is particularly accessible and therefore well suited to our approach. We find that the dendritic branches of the neurones examined change appreciably over intervals, of 2 weeks or more; some branches retract, others elongate and others seem to form de novo. The apparent remodelling of these postsynaptic elements implies that the synaptic connections of these cells normally undergo significant rearrangement beyond what is usually considered to be the developmental period.

The distribution of bovine pancreatic polypeptide/FMRFamide‐like immunoreactivity in the ventral nervous system of the locust

Abstract: The distribution of bovine pancreatic polypeptide (BPP) FMRFamide-like immunoreactivity is described in the ganglia of the ventral nerve cord and in the peripheral median nervous system of the locust, Schistocerca gregaria. Immunoreactive cell bodies occur in three regions of the thoracic ganglia: 1) two pairs of cells lie in the anterior of the ganglion ventral to the root of nerve 1 and the anterior ventral association centre; 2) a group of cells lies in the ventral midline at the level at which nerves 3 and 4 leave the ganglion; 3) and two bilaterally symmetrical, posterior lateral groups lie between nerves 5 and 6 at the edge of the ganglion. Immunoreactive cell bodies in the suboesophageal and abdominal ganglia are confined to the midline and are distributed along the anterior-posterior axis both dorsally and ventrally. The processes of the posterior lateral groups have been traced into the neurohaemal organs of the median nerve and beyond. In the periphery such processes innervate the salivary glands and various muscles. The nature of the endogenous antigen contained in the immunoreactive cells has been investigated with the use of antisera against other peptides of the pancreatic polypeptide family, namely avian pancreatic polypeptide, neuropeptide Y, and peptide YY. In addition, BPP antisera not specific for the C terminal hexapeptide have been tested. Liquid preabsorption experiments with BPP and FMRFamide (the molluscan cardioacceleratory peptide) suggest that the endogenous peptide antigen contained in the stained neurones may belong to the pancreatic polypeptide family or to the FMRFamide family.

Initial appearance and regional distribution of the neuron-glia cell adhesion molecule in the chick embryo.

Abstract: This study represents a global survey of the times of the first appearance of the neuron-glia cell adhesion molecule (Ng-CAM) in various regions and on particular cells of the chick embryonic nervous system. Ng-CAM, originally characterized by means of an in vitro binding assay between glial cells and brain membrane vesicles, first appears in development at the surface of early postmitotic neurons. By 3 d in the chick embryo, the first neurons detected by antibodies to Ng-CAM are located in the ventral neural tube; these precursors of motor neurons emit well-stained fibers to the periphery. To identify locations of appearance of Ng-CAM in the peripheral nervous system (PNS), we used a monoclonal antibody called NC-1 that is specific for neural crest cells in early embryos to show the presence of numerous crest cells in the neuritic outgrowth from the neural tube; neither these crest cells nor those in ganglion rudiments bound anti-Ng-CAM antibodies. The earliest neurons in the PNS stained by anti-Ng-CAM appeared by 4 d of development in the cranial ganglia. At later stages and progressively, all the neurons and neurities of the PNS were found to contain Ng-CAM both in vitro and in vivo. Many central nervous system (CNS) neurons also showed Ng-CAM at these later stages, but in the CNS, the molecule was mostly associated with neuronal processes (mainly axons) rather than with cell bodies; this regional distribution at the neuronal cell surface is an example of polarity modulation. In contrast to the neural cell adhesion molecule and the liver cell adhesion molecule, both of which are found very early in derivatives of more than one germ layer, Ng-CAM is expressed only on neurons of the CNS and the PNS during the later epoch of development concerned with neural histogenesis. Ng-CAM is thus a specific differentiation product of neuroectoderm. Ng-CAM was found on developing neurons at approximately the same time that neurofilaments first appear, times at which glial cells are still undergoing differentiation from neuroepithelial precursors. The present findings and those of previous studies suggest that together the neural cell adhesion molecule and Ng-CAM mediate specific cellular interactions during the formation of neuronal networks by means of modulation events that govern their prevalence and polarity on neuronal cell surfaces.

Peripheral inflammatory vascular disease in Sjögren's syndrome. Association with nervous system complications.

Abstract: Two histopathologic types of inflammatory vascular disease (IVD) occur in Sjogren's syndrome (SS): mononuclear IVD (MIVD) and neutrophilic IVD (NIVD) We describe 50 SS patients with IVD (30 with NIVD and 20 with MIVD) Thirty-three (66%) of the SS patients with biopsy-documented IVD had nervous system disease unattributable to other causes Nineteen patients (58%) had involvement of both the central and peripheral nervous systems, while 9 had peripheral and 5 had central nervous system dysfunction alone Patients with both histopathologic types of IVD were at risk for the development of nervous system abnormalities (57% of NIVD patients and 80% of MIVD patients) Indirect evidence is presented which suggests that IVD may play a role in the immunopathogenesis of nervous system disease, at least in a subset of SS patients

Biochemical and immunocytological localization of molluscan small cardioactive peptides in the nervous system of Aplysia californica.

Abstract: High pressure liquid chromatography (HPLC) followed by bioassay on isolated snail hearts were used to locate two related peptides, termed small cardioactive peptides A and B (SCPA and SCPB) in each of the central ganglia of Aplysia. The peptides are most concentrated in the buccal ganglia, the ganglia involved in the control of feeding movements. Immunocytology with antisera raised to conjugated SCPB stained three groups of neurons in the buccal ganglia. One group consisted of relatively small neurons that were tightly clustered. The second group was comprised of larger neurons that were more scattered. The third group was made up of several neurons including the two largest in the ganglia, identified cells B1 and B2. B1 and B2 and other neurons in this group innervate the gut by way of the esophageal nerve. HPLC-bioassay of single, individually dissected B1 or B2 neurons demonstrated that the two peptides are present in a single cell. For B2, but not B1, choline injected into the cell body was converted to the conventional transmitter, acetylcholine. This indicates that, in addition to the two peptides, B2 also contains choline acetyltransferase, and raises the possibility that acetylcholine and the SCPs may act as co-transmitters in B2. Strong immunocytological staining of fibers and varicosities was observed in the neuropilar region of the cerebral, pleural, pedal, and abdominal ganglia. In addition to the buccal ganglia, immunoreactive neurons were observed in all of the other central ganglia. The high concentration of the SCPs and the relatively large number of immunoreactive neurons in the buccal ganglion suggest a particularly important role of these peptides specifically in feeding behavior. However, the widespread occurrence of the SCPs in fibers and neuronal cell bodies throughout the nervous system suggests that these peptides also may have additional behavioral functions in Aplysia.

FMRF-amide-like substances in the leech. I. Immunocytochemical localization.

Abstract: FMRF-amide-like immunoreactivity (FLI) was localized to approximately 50 neurons in each segmental ganglion of the medicinal leech using immunocytochemical techniques. Although most of these neurons were iterated in each segmental ganglion, some were more restricted in their segmental distribution. The head and tail ganglia likewise contained numerous FMRF-amide-like immunoreactive cells. In addition to cell bodies, many nerve processes and varicosities were also immunoreactive throughout the ganglion. All labeling of FLI was blocked by preabsorption of the anti-FMRF-amide antiserum with synthetic FMRF- amide. Using a combination of Lucifer Yellow cellular injection and indirect immunofluorescence techniques, we identified several of the neurons possessing FLI. Identified neurons included excitatory motor neurons (HE, RPE, LPE, AE, and L), the HA modulatory neuron, interneuron cell 204, and cells of unknown function (AP). The processes of HE motor neurons and HA modulatory neurons which innervate the heart tubes were also immunoreactive. These results indicate a role for FMRF- amide-like substances as neurochemical signals in the leech.

The brain of the planarian as the ancestor of the human brain.

Abstract: The planarian is the simplest living animal having a body plan of bilateral symmetry and cephalization. The brain of these free-living flatworms is a bilobed structure with a cortex of nerve cells and a core of nerve fibres including some that decussate to form commissures. Special sensory input from chemoreceptors, photoreceptor cells of primitive eyes, and tactile receptors are integrated to provide motor responses of the entire body, and local reflexes. Many morphological, electrophysiological, and pharmacological features of planarian neurons, as well as synaptic organization, are reminiscent of the vertebrate brain. Multipolar neurons and dendritic spines are rare in higher invertebrates, but are found in the planarian. Several neurotransmitter substances identified in the human brain also occur in the planarian nervous system. The planarian evolved before the divergence of the phylogenetic line leading to vertebrates. This simple worm therefore is suggested as a living example of the early evolution of the vertebrate brain. An extraordinary plasticity and regenerative capacity, and sensitivity to neurotoxins, provide unique opportunities for studying the reorganization of the nervous system after injury. Study of this simple organism may also contribute to a better understanding of the evolution of the human nervous system.

Promoting functional plasticity in the damaged nervous system.

Abstract: Damage to the central and peripheral nervous system often produces lasting functional deficits. A major focus of neuroscience research has been to enhance functional restitution of the damaged nervous system and thereby produce recovery of behavioral or physiological processes. Promising procedures include surgical, physical, and chemical manipulations to reduce scar formation and minimize the disruption of support elements, administration of growth-stimulating substances, tissue grafts to bridge gaps in fiber pathways, and embryonic brain tissue grafts to provide new cells with the potential to generate fiber systems. Two elements are required for functional nervous system repair: (i) neurons with the capacity to extend processes must be present, and (ii) the regenerating neurites must find a continuous, unbroken pathway to appropriate targets through a supportive milieu.

Light and electron microscopic evidence of transneuronal labeling with WGA‐HRP to trace somatosensory pathways to the thalamus

Abstract: Horseradish peroxidase conjugated to wheat-germ lectin is being used with increasing frequency as an anterograde label to trace pathways in the nervous system, owing to the sensitivity of the method and ease of use However, it has been suggested that horseradish peroxidase conjugated to wheat-germ lectin may be transneuronally transported, thus affecting the ease of interpretation of the results The present study used the projections of the dorsal column nuclei and spinal cord to the thalamus as a model system to determine whether transneuronal transport could be demonstrated and whether the degree of such transport was related to the size of the injection site Light microscopic observation of sections incubated with tetramethyl benzidine after large injections (1 μL of a 10% solution of horseradish-peroxidase-conjugated wheat-germ lectin in water) in the dorsal column nuclei demonstrated the presence of labeled neurons in the nucleus reticularis thalami, which is not known to receive afferents from or project to these nuclei The electron microscopic study, although based upon the use of the chromogen benzidine dihydrochloride, less sensitive than tetramethyl benzidine, revealed the existence of labeled neurons in the thalamic ventrobasal complex This is unlikely to be due to retrograde labeling and is therefore interpreted as a result of transneuronal, perhaps transsynaptic, transport Glial and perivascular cells also contained granules of reaction product in some cases Smaller injections (100 nL) in the dorsal column nuclei, on the other hand, did not produce this apparent transneuronal labeling After small injections (100 nL) in the spinal cord, anterograde labeling was observed mainly in the thalamic ventrobasal complex in the rat, and in the posterior group in the cat, and the nuclei centralis lateralis and submedius in both species, as has been described in numerous other studies After large injections, additional labeled areas were observed in the posterior intralaminar region (parafascicular-center median complex), in the medial thalamus (nuclei reuniens, rhomboid and paraventricular), and in the cat, in the ventroposterolateral nucleus In the rat, experiments were performed in which a kainic acid injection was made to induce neuronal loss in the nucleus reticularis gigantocellularis of the medulla, which is a relay of the spinoreticulothalamic pathway, known to project to some of these thalamic areas After such lesions and large spinal injections of horseradish-peroxidase-conjugated wheat germ lectin, labeling was clearly decreased in some of these additional sites of projection and not in the areas which contained labeling after small injections, thus demonstrating that nucleus reticularis gigantocellularis neurons are necessary for some of the additional labeling N-methyl DL aspartic acid was applied to the spinal cord in other rats, destroying dorsal horn neurons but not axons of other systems Horseradish-peroxidase-conjugated wheat germ lectin injected into the spinal cord of these animals resulted in retrograde labeling of brain stem neurons, but the loss of labeled fibers in the thalamus, which suggested that collaterals of brain stem neurons are not the source of transport of the tracer from cord to medial thalamus The results of the present study suggest the possibility of significant transneuronal labeling when horseradish-peroxidase-conjugated wheat germ lectin is used to trace anterograde transport in somatosensory pathways, especially when large volumes of it are injected Thus, it is necessary to interpret the results of these tract-tracing experiments with caution Some mechanisms which may subserve such transneuronal labeling are proposed