Showing papers on "Nervous system published in 1979"

Miller's anatomy of the dog

Abstract: * The Dog and Its Relatives Introduction and Breeds Phylogenetic Relationships of Canids to Other Carnivores Origin and Domestication of the Dog * Prenatal Development * The Integument * The Skeleton * Arthrology * The Muscular System * The Digestive Apparatus and Abdomen * The Respiratory System * The Urogenital System * The Endocrine System * The Heart and Arteries * The Veins * The Lymphatic System * Introduction to the Nervous System * The Autonomic Nervous System * Spinal Cord and Meninges * The Spinal Nerves * The Brain * Cranial Nerves and Cutaneous Innervation of the Head * The Ear * The Eye

Extracellular potassium in the mammalian central nervous system.

Abstract: Potassium, calcium, and magnesium are three inorganic ions that occur in significant quantity in extracellular fluid of the mammalian brain and have powerful effects on the functioning of nervous tissue. In different ways all three influence the excitability of neurons and the release of transmitters from presynaptic terminals. Two different points of view have evolved concerning the regulation of these ions in the central nervous system (CNS). Some authors have emphasized the narrow range of the activity of these ions in the healthy brain and have concluded that stability of brain function requires stability of the extracellular activity of these ions. Others have argued that in the course of evolution the mammalian brain must have found an advantageous use for these powerful agents in the normal regula­ tion of neuronal excitability. According to this view, programmed varia­ tions in [K+]o, [Ca2+]o, and perhaps also [Mg2+]o may be an integral component in the normal function of the central nervous system. Due to the recent development of potassium-selective microelectrodes (184) there has been a new surge of interest in the functional significance of potassium distribution in the nervous system. This selective review may be supplemented by consulting more general reviews on brain electrolytes (69, 72, 74, 83, 90, 158, 175).

Distribution of glutamine synthetase in the rat central nervous system.

Abstract: The results of a light microscopic immunohistochemical study of glutamine synthetase in rat nervous system are presented. In all sites studied the enzyme was confined to astrocytes. Except for trace amounts in ependymal cells, the enzyme was not observed in other cells of the nervous system including neurons, choroid plexus, third ventricular tanycytes, subependymal cells and mesodermally-derived elements. The intensity of astrocyte staining varied in different regions with the greatest degree noted in the hippocampus and cerebellar cortex while the least was noted in brain stem, deep cerebellar nuclei and spinal cord. The glutamine synthetase content correlated well with sites of suspected glutamergic activity in keeping with the view of a critical role of astrocytes in the regulation of the putative neurotransmitter glutamic acid.

Myelin-associated glycoprotein demonstrated immunocytochemically in myelin and myelin-forming cells of developing rat.

Abstract: The unlabeled peroxidase-antiperoxidase method has been used with antiserum against "myelin-associated glycoprotein" to establish the presence of the glycoprotein in myelin and myelin-forming cells of the developing rat nervous system. Myelin-associated glycoprotein is found in oligodendroglial cytoplasm before the beginning of myelination. Staining intensity of oligodendroglia increases during early development and slowly declines during the period of rapid myelination. Myelin staining is confined to the periaxonal region of the myelin sheath and does not increase as large, compact sheaths are formed. Antiserum to central nervous system myelin-associated glycoprotein also stains Schwann cells in developing trigeminal ganglia and the periaxonal region of peripheral myelin sheaths.

Measurement of neuron-specific (NSE) and non-neuronal (NNE) isoenzymes of enolase in rat, monkey and human nervous tissue.

Abstract: Four double antibody solid-phase radioimmunoassay systems are described for the measurement of neuron-specific enolase (NSE) and non-neuronal enolase (NNE) from rat, monkey and human brain tissue. NSE and NNE are antigenically distinct, making their respective assays specific. The levels of neuronal and non-neuronal enolase (an enolase recently shown to be localized in glial cells) are determined in various regions of rat, monkey and human nervous system. Both neuronal and glial enolases are major proteins of brain tissue with each representing about 1.5% of total brain soluble protein. NSE levels are highest and NNE levels lowest in brain areas having a high proportion of grey matter, such as the cerebral cortex. The reverse is true for areas high in white matter, such as the pyramidal tract and the corpus callosum. Peripheral nervous system levels of NSE are much lower than those of brain with the spinal cord intermediate between the two. Radioimmunological and immunocytochemical data show that neuron-specific enolase is also present in neuroendocrine cells located in non-nervous tissue, which include pinealocytes, parafollicular cells of the thyroid, adrenal medullary chromaffin cells, glandular cells of the pituitary and Islet of Langerhans cells in the pancreas. Unlike neurons, these cells also contain non-neuronal enolase in high amounts.

Experimental autoimmune model of nerve growth factor deprivation: Effects on developing peripheral sympathetic and sensory neurons

Abstract: An experimental autoimmune model of nerve growth factor (NGF) deprivation has been used to assess the role of NGF in the development of various cell types in the nervous system. Adult rats immunized with 2.5S mouse NGF in complete Freund's adjuvant produced antibodies that crossreacted with their own NGF and that were transferred in utero to the fetus and in milk to the neonate. Cross-fostering experiments were carried out to separate the effects of exposure to anti-NGF in utero from those due to exposure through the milk. Anti-NGF transferred in utero and in milk resulted in the destruction of peripheral sympathetic neurons assessed by morphological methods (light microscopy) and biochemical methods (tyrosine hydroxylase activity, choline acetyltransferase activity, and protein content). No effects were observed on the adrenal medulla. Offspring of NGF-immunized females exposed to anti-NGF in utero had a decreased protein content in the dorsal root ganglia and were unable to transport (125)I-labeled NGF injected in the forepaw to the dorsal root ganglia. These results suggest that a subpopulation of sensory neurons is dependent on NGF for survival during some period of fetal development. This model offers the potential for determining the degree and time of dependence of various cell types on NGF.

Delta-aminolaevulinic acid is a potent agonist for GABA autoreceptors.

Abstract: ACUTE attacks of the hereditary hepatic porphyrias are frequently accompanied by neuropsychiatrie symptoms. The presentation of nervous system involvement varies; in decreasing order of frequency, there may be motor neuropathy, confusion, psychiatric manifestations, hyperexcitability and epileptic-type seizures1. Psychiatric manifestations include depression, anxiety, insomnia and an organic brain syndrome2. Although the aetiology of the neural dysfunction in the acute attack is unknown, several mechanisms have been suggested at a neurochemical level. It is possible that porphyrin precursors, which are produced in excess by the liver during acute episodes, gain access to the nervous system and exert direct neurotoxic effects3–5; alternatively, a metabolic defect in haem biosynthesis in nerve cells might result in a functional haemoprotein deficiency which becomes critical at the time of the acute attack6. The porphyrin precursor, δ-aminolaevulinic acid (δ-ALA), exhibits various effects in mammalian central nervous tissue preparations. It inhibits high-affinity uptake and increases efflux of γ-aminobutyric acid (GABA)3 and L-glutamate4 in rat cortical synaptosomes; it also inhibits the (Na+ + K+) ATPase isolated from rabbit brain and red blood cells7. These effects occur only at relatively high concentrations of δ-ALA (at least 10−4M), and it is very unlikely that such concentrations are reached in the brain during acute porphyric attacks8. Recently, there has been strong evidence that release of GABA is subject to negative feedback control through presynaptic receptors on GABAergic terminals9–11. Here we report that δ-ALA inhibits potassium-stimulated release of GABA from preloaded synaptosomes, probably by acting as an agonist at these presynaptic receptors. This effect is evident at concentrations of δ-ALA (10−6M) which are well within levels recorded in the cerebrospinal fluid of porphyric patients showing neuropsychiatrie symptomatology12.

Regrowth of severed axons in the neonatal central nervous system: establishment of normal connections

Abstract: When pyramidal tract axons are cut in the adult hamster, fibers degenerate in both anterograde and retrograde directions from the lesion. If the same operation is performed on infant hamsters, however, there is massive regrowth of the severed axons via a new brainstem pathway to their appropriate terminal sites in the medulla and spinal cord. In contrast to previous studies, these results suggest that axons in the mammalian central nervous system damaged early in life may regenerate in a functionally useful way.

Presynaptic Inhibition: Transmitter and Ionic Mechanisms

Abstract: Publisher Summary This chapter discusses the pharmacology and ionic mechanism of presynaptic inhibition in both invertebrates and vertebrates. For invertebrates, the chapter mainly focuses on crustacean nervous system. Pharmacological and anatomical studies suggest that the inhibition results from the release of gamma-aminobutyric acid (GABA) from axo-axonic synapses. There is evidence that in mammalian CNS presynaptic fibers may have GABA receptors even though they do not receive axo-axonic synapses. In addition, electrical stimulation of these presynaptic fibers results in the activation of these receptors, presumably due to the diffusion of GABA from remote synapses. This raises the possibility that presynaptic inhibition might occur in regions that do not contain axo-axonic synapses. In vertebrates, there is evidence that GABA, at least on the cell bodies of primary afferents, increases chloride permeability. At the crustacean neuromuscular junction (NMJ) the increased conductance of the motor nerve terminal results in a reduction in spike amplitude and/or a block in impulse invasion into the terminal that reduces the number of quanta released per stimulus. The major difference in the presynaptic action of GABA in vertebrate primary afferents and in the crustacean NMJ is that in the former, the increased chloride conductance results in a large depolarization.

In vivo demyelination induced by intraneural injection of anti-galactocerebroside serum: a morphologic study.

Abstract: Intraneural injection of rabbit anti-galactocerebroside (anti-GC) serum produced focaldemyelinative lesions in rat sciatic nerves. Recipient rats developed a sensory motordeficit of the toes and feet on the side injected with anti-GC serum. Schwann cellabnormalities in recipient nerves were apparent by 20 minutes, followed by myelinsplitting and vesiculation over the next 8 hours. Macrophages first appeared in moder-ate numbers by 15 hours, and degraded myelin was completely phagocvtized by 5 days.An acute inflammatory reaction consisting of endoneurial edema, polymorphonuclearcell infiltration, and fibrin extravasation also was prominent. In vivo demyelinativeactivity of rabbit anti-GC serums was removed by pre-incubation with GC or central orperipheral nervous system myelin and was also lost when the serums were heated at 56C for 30 minutes and injected into nerves of rats previously injected with cobra venomfactor. Anti-GC antibodies are present in the serum of rabbits with experimentalallergic neuritis (WNV-EAN) and encephalomyelitis (WM-EAE) produced, respectively,by immunization with whole peripheral nerve or brain white matter and may play arole in the pathogenesis of demyelination in GC-induced EAN, WN-EAN, or WM-EAE.

Identified neurones isolated from leech CNS make selective connections in culture.

Abstract: Neurones cultured in vitro offer distinct advantages for studying how processes grow towards their targets and form synaptic connections. In contrast to the complex events occurring during the development of the nervous system, synapse formation in culture can be analysed in a few neurones at a time and under controlled conditions1. We have now dissected out and cultured single identified neurones from the central nervous system (CNS) of the adult leech. Various types of sensory cells, motor cells, and interneurones can be identified in leech ganglia—each with a stereotyped set of properties, including: (1) the electrical characteristics of its membrane, (2) the arborisation of its branches and the morphology of its terminals and (3) the pattern of connections it makes with other identified neurones, skin or muscle2. Thus, cultured cells can be compared in detail with their counterparts in situ. We have found that isolated cells survive for several weeks, maintain their membrane properties, sprout and form selective connections.

Localization of Hypophysiotropic Peptides and other Biologically Active Peptides within the Brain

Abstract: Immunohistochemical analysis of hypophysiotropic and other neuropeptides reveals unique and striking neural perikarya, axons, and terminals containing specific peptide immunoreactivity. The hypophysiotropic peptides are most highly concentrated in nerve terminals in the external layer of the median eminence. From this site they may be released and carried via the portal circulation to the adenohypophysis. The occurrence of hypophysiotropic peptides in other areas of the nervous system suggests that they may act, at these sites, as neurotransmitters. Enkephalins, SP, angiotensin II, and cholecystokinin-like immunoreactivity are also found in nerve terminals in the external layer of the median eminence of some species. Although these peptides have not been considered hypophysiotropic hormones, the location of their terminals in the median eminence suggests that they participate indirectly in regulation of anterior pituitary hormone release. This control may be accomplished via axo-axonal influences of terminals containing these peptides upon the terminals containing the genuine hypophysiotropic peptides. An analogous interaction is thought to be exerted by dopamine terminals upon LHRH terminals in the median eminence (39). All of the neuropeptides discussed above are found within neuronal structures in the hypothalamus. Most of these peptides are also found, at least to a limited extent, in the brainstem, spinal cord, and deep nuclei of the telencephalon. Few peptides have been localized in neurons of the cerebral cortex. These include SOM, VIP, and cholecystokinin-like immunoreactivity. The cerebellum, to date, has not been shown to contain significant immunoreactivity for any of the presently identifiable neuropeptides. The demonstration of the coexistence of neuropeptides (SOM and SP) in some monoaminergic (adrenergic and serotonergic) neurons raises questions about the one-neuron-one-transmitter hypothesis. It is presently unknown whether or not such coexistence is widespread in the mammalian nervous system. For those neurons that contain two neuroeffector substances, it will be important to determine whether or not both substances play an active role in the function of the neuron. Finally, the details of the morphological interactions of peptidergic elements with other neuronal systems offer the possibility to understand more completely the circuitry of many regions of the central nervous system.

Host defenses in herpes simplex infections of the nervous system: effect of antibody on disease and viral spread.

Abstract: BALB/c mice passively immunized with antibody to herpes simplex virus type 1 and challenged in the footpad with 10(5.7) plaque-forming units of herpes simplex virus type 1 were shown to be protected from neurological disease and death compared with control mice treated with normal serum or antibody to Sindbis virus. One hundred percent of untreated mice had virus recoverable from dorsal root ganglia by 48 h after infection. Whereas amputation of the infected limb at 48 h had no effect, antibody administration (resulting in titers of 1:8 and 1:16) was found to prevent acute neurological disease if administered no later than 48 h after infection. Antibody also restricted the extent of latent infection in the lumbosacral ganglia. The data provide strong evidence that antibody is effective in preventing spread of virus both in the peripheral nervous system and in central nervous system (spinal cord) tissue.

Fine structural studies of the nervous system and the apical organ in the planula larva of the sea anemone Anthopleura elegantissima.

Abstract: The nervous system of the planula larva of Anthopleura elegantissima consists of an apical organ, one type of endodermal receptor cell, two types of ectodermal receptor cells, central neurons and nerve plexus. Both interneural and neuromuscular synapses are found in the nerve plexus. The apical organ is a collection of about 100 long, columnar cells each bearing a long cilium and a collar of about 10 microvilli. The cilia of the apical organ are twisted together to form an apical tuft. The ciliary rootlets of the apical organ cells are extremely long, reaching to the basal processes of the cells adjacent to the mesoglea. All three types of sensory cells are tall and slender in profile and are identified by the presence of one or more of the following features: microtubules, small vesicles, membrane-bound granules and synapses. The interneurons are bipolar cells with somas restricted to the aboral end, adjacent to the apical organ. All synapses observed are polarized or asymmetrical. A diagram including all the elements of the nervous system is presented and the possible functions of the nervous system are discussed in relation to larval behavior.

Substance P: evidence for diverse roles in neuronal function from cultured mouse spinal neurons.

Abstract: Mouse spinal neurons grown in tissue culture were used to examine the membrane mechanisms of action of the peptide substance P. Two functionally distinct actions were observed, one being a rapidly desensitizing excitation, and the other being a dose-dependent, reversible depression of excitatory responses to the putative amino acid neurotransmitter glutamate. These effects on excitability suggest that substance P may play more than one role in intercellular communication in the nervous system.

Synapses between neurones in the central nervous system of the leech.

Abstract: CONTENTS

Neurobiology of Polyorchis. II. Structure of effector systems

Abstract: The gross and fine morphology of the major effector systems in the anthomedusan, Polyorchis penicillatus, is described and discussed in relation to the known physiological and behavioral properties of these systems. Swimming is controlled by an anastomosing network of giant neurons within the inner nerve ring and radial nerves. Although these neurons may be coupled by gap junctions it is likely that they form a syncytium. The photosensitivity of the "giants" is attributed to reflexive membranes within the cytoplasm. Giant neurons act as both the pre- and postsynaptic cell when forming synapses with other neurons of the inner nerve ring. Neuromuscular synapses between "giants" and the striated swimming muscle are found around the margin and along the radii. Swimming muscle cells are connected laterally by gap junctions and end-to-end by desmosomes which are sometimes elaborated with extra-thick filaments. Unstriated sphincter and radial muscles, the major muscles associated with crumpling, are both greatly folded over mesogloeal ridges and have processes that cross the mesogloea to contact the ring and radial canals, respectively. Synapses or other sites that might be responsible for exciting these muscles during crumpling have not been found. The ability of the endodermal lamella and canals to propagate action potentials can be accounted for by the numerous gap junctions that are seen in these tissues. The precise location where excitation is transferred to the nervous system to initiate crumpling is not known but epithelial bridges crossing the mesogloea are likely routes. Synapses between neurons originating in the outer nerve ring and tentacle longitudinal muscle can account for the control of tentacle length. Neurons of the outer nerve ring also synapse onto velar, radial fibers and the sphincter muscle. The inner and outer nerve rings have nervous connections. The organisation of the outer nerve ring and the arrangement of nerves within the endodermal plexus is described. A diagram showing the major connections and interactions of components of the effector systems is presented.

Nervous system involvement in type IV glycogenosis.

Abstract: A 30-month-old girl exhibited the 19th known case of type IV glycogenosis. Extensive involvement of the nervous system was found at autopsy. This represents only the second patient in whom the fine structure of the CNS and skeletal muscle has been described. We have also identified the abnormal polysaccharide in peripheral nerve, a finding that, to our knowledge, has not been reported previously. Our review of the literature indicates that approximately 50% of these patients exhibit signs or symptoms referable to the neuromuscular system. Most clinical and pathologic studies have focused on the severe liver involvement; insufficient attention has been directed toward the nervous system. This emphasizes the need for more detailed neurologic and neuropathologic examinations of children with type IV glycogenosis.

The nervous system

Abstract: Although some progress has been made towards a functional analysis of the cyclostome spinal cord, this task has been made more difficult by virtue of its peculiar characteristics which have impeded direct comparisons with the distribution of the cells and fibres in the spinal cord of higher vertebrates. The unique ribbon-like shape of the cord (said to be shared only by Latimeria) is almost certainly a secondary acquisition, since a more usual cylindrical form is present in earlier ontogenetic stages. Whiting (1972) considers that this flattened shape may have been due to the downward expansion of the dorsal fat column; a structure that he believes may already have been developed by heterostracans (Section 4.4). In the absence of medullated nerve fibres there is no sharp division between white and grey matter, although the cells form a broad central mass surrounded by the fibres. Distinct dorsal and ventral horns are also missing and the dorsal and ventral spinal nerve roots of the lamprey are unique in failing to unite. In myxinoids, where the nerve roots do unite, these junctions lie far outside the spinal cord in the region of the parietal muscles.

The chromaffin and chromaffin-like cells in the autonomic nervous system.

Abstract: Publisher Summary This chapter discusses the chromaffin and chromaffin-like (CCL) cells in the autonomic nervous system. It has been known for a long time that there were clusters of chromaffin cells scattered along and within the nerves and ganglia of the autonomic nervous system when new interest in these cells was aroused about 1960 because they could represent a structural basis for explanation of special features of the synaptic transmission in the sympathetic ganglia. They were considered chromaffin cells, as their shape and fluorescence was identical to those of the adrenomedullary cells. There is a striking diversity in the shape and connections, and probably in the functions, of CCL cells located within the autonomic nervous system or in close association with it. The present state of research is still far from covering all the vertebrate groups equally, and the variety of the situations already described suggests that a more extensive analysis will again reveal new models.

Somatostatin-Immunoreactive Nerve Cell Bodies and Fibers in the Medulla Oblongata et Spinalis

Abstract: Complete serial sectioning ofthe medulla oblongata in monkey, cat, guinea pig, andjapanese dancing mouse and incubation for somatostatin-immunoreaction was carried out. Numerous regions of the medulla oblongata such as the nucleus reticularis gigantocellularis, nucleus cuneatus et gracilis, nucleus raphe magnus, nucleus tractus solitarius, nucleus vestibularis, and parts of the oliva contain dense networks of somatostatin-immunoreactive nerve fibers. Cell bodies were seen in the nucleus reticularis medullae oblongatae. In the spinal cord the sections from each segment were analyzed, showing the highest concentrations of somatostatinergic fibers in the substantia gelatinosa of the columna dorsalis. Cell bodies were seen in the zona intermedia centralis, especially in the upper cervical segments. Many positive fibers were also seen in the entire zona intermedia and the columna ventralis. Especially prominent was the immunoreactivity in the zona intermediolateralis of the thoracic segments and the columna ventralis of the lower lumbar and sacral segments. Recently more precise data have become available for the exact distribution of neuropeptides because several working groups have started a careful mapping of these substances by immunocytochemistry (2, 3, 6, 7, 9-12).’ However, complete data are not available since entire serial sectioning through the whole central nervous system has not yet been effected in connection with immunostaining. The actual increase of information on the regional distribution depends upon two factors: (1) how closely the sequential serial sectioning of the nervous system is carried out, and (2) how sensitive and specific the applied method is with detecting the single smallest amount of neuropeptides. We have carried out a study using complete serial sections of 10 �t through the brains or brain stems ofvarious mammals and interrupted series of each spinal cord segment. � The results for somatostatin immunoreactive structures show that this procedure reveals new information of peptide systems in the central nervous system.