Ion Channel Topography of the Neuronal Nicotinic Acetylcholine Receptor: Pharmacochemical Approaches

Forty-three bisammonium ganglionic blockers were synthesized to study the structure of the ion channel of nicotinic acetylcholine receptor. The conformational parameters of these blockers were studied, and their effects toward the ganglionic transmission in situ on the sympathetic feline superior cervical ganglia and in vitro on the parasympathetic guinea-pig small intestine ganglia were determined. A model of the binding site for the bisammonium ganglionic blockers in the neuronal ion channel was proposed.     

Effect of Precursors on the Synthesis of Catecholamines and on Neurotransmission in the Superior Cervical Ganglion of the Rat

Abstract: Male Sprague-Dawley rats (325–350 g) were anesthetized with urethane (1.5 g/kg i.p.) and treated with physiological saline, Aspartame (APM; 552 μmol/kg), or tyrosine (Tyr; 552 μmol/kg). Ganglionic transmission and the synthesis of dopamine (DA) and norepinephrine (NE) were measured in the superior cervical ganglion (SCG) following electrical stimulation of the cervical sympathetic trunk (CST). When the CST was stimulated with single pulses, neither APM nor Tyr affected the synthesis of NE or DA. However, in response to low- (5 Hz, 20 s) and high- (20 Hz, 20 s) frequency pulses, the metabolism of DA was increased (p > 0.05), but to the same extent after saline, APM, or Tyr. In rats stimulated with similar low- and high-frequency pulses, the synthesis of NE was increased significantly (p > 0.05) after Tyr, but not after APM or saline. In saline-treated controls, ganglionic transmission was not changed in response to single pulses, or low- or high-frequency stimulation. However, after treatment with APM, ganglionic transmission was depressed significantly (p > 0.01) in response to high-frequency stimulation (single: 0.46 ± 0.09 mV; low: 0.39 ± 0.07 mV; high: 0.27 ± 0.07 mV). After treatment with Tyr, ganglionic transmission was depressed significantly (p > 0.05) in response to both low- and high-frequency stimulation (single: 0.44 ± 0.04 mV; low: 0.22 ±0.12 mV; high: 0.26 ± 0.07 mV). In the nonstimulated SCG, l-3,4-dihydroxyphenylalanine (25 mg/kg) caused a rapid, significant (p > 0.01) increase in the synthesis and metabolism of DA, but not of NE. Treatment with nialamide (200 mg/kg i.p.) followed by electrical stimulation (15 Hz, 15 min) of the CST caused a significant (p > 0.05) increase of both NE and DA in the stimulated SCG. It is concluded that there are both similarities and differences in the regulation of the synthesis of NE and in the modulation of ganglionic transmission after the administration of the precursors APM and Tyr. The results indicate that caution is needed in comparing the neurochemical and neurophysiological effects of different catecholamine precursors.     

ELECTROPHORETIC CHARACTERIZATION OF LEUCINE-, GLUCOSAMINE- AND FUCOSE-LABELLED PROTEINS RAPIDLY TRANSPORTED IN FROG SCIATIC NERVE

—[³H]Leucine, [³H]glucosamine and [³H]fucose were incorporated in vitro into proteins in frog sciatic ganglia and subsequently transported at a rapid rate along the sciatic nerve towards a ligature, in front of which they accumulated. The synthesis of transported fucose-labelled proteins is closely linked to protein synthesis but is not dependent on RNA synthesis, as judged by effects after incubation for 17 h in the presence of cycloheximide and actinomycin D. Labelled ganglionic as well as transported material were solubilized in sodium dodecyl sulphate and characterized by polyacrylamide gel electrophoresis. The bulk of ganglionic proteins, labelled with any of the precursors used, had molecular weights exceeding 40,000. The radioactivity patterns of leucine- and glucosamine-labelled ganglionic proteins showed similarities with dominant peaks corresponding to molecular weights of about 75,000 and 50,000. The last peak was almost lacking in fucose-labelled ganglionic components. Leucine- and glucosamine labelled-transported proteins exhibited characteristic and similar electrophoretic distributions in contrast to the pattern of fucose-labelled nerve proteins, which was more polydisperse. The most conspicious nerve proteins corresponded to molecular weights of about 75,000 and 18,000. There was a remarkable agreement in the profile of leucine-labelled transported nerve proteins and fucose-labelled ganglionic proteins. In the light of these observations the possibility that glycoproteins constitute a large part of rapidly transported proteins will be discussed.     

Dual effects of proctolin on the rhythmic burst activity of the cardiac ganglion

The neuropeptide proctolin has distinguishable excitatory effects upon premotor cells and motorneurons of Homarus cardiac ganglion. Proctolin's excitation of the small, premotor, posterior cells is rapid in onset (5–10 s) and readily reversible (< 3 min). Prolonged bursts in small cells often produce a “doublet” ganglionic burst mode via interactions with large motorneuron burst-generating driver potentials. In contrast to small cell response, proctolin's direct excitatory effects upon motorneuron are slow in onset (60–90 s to peak) and long-lasting (10–20 min). The latter include: (a) a concentration-dependent (10^?9–10^?7M) depolarization of the somatic membrane potential; (b) increases in burst frequency and (c) enhancement of the rate of depolarization of the interburst pacemaker potential. Experiments on isolated large cells indicate: (a) the slow depolarization is produced by a decrease in the resting G_K and (b) proctolin can produce or enhance motorneuron autorhythmicity. A two-tiered non-hierarchical network model is proposed. The differential pharmacodynamics exhibited by the two cell types accounts for the sequential modes of ganglionic burst activity produced by proctolin.     

Differentiation of the interstitial cell line in hydrozoan planulae

Repopulation of epithelial (colchicine-treated) planular tissue by interstitial cells, nematoblasts/nematocytes, and ganglionic cells was examined via grafting. Seventy-two-hour epithelial planular head pieces were grafted to 72-hour control labelled planular tail pieces, left in contact for 24 h, separated, and the head pieces were analyzed for interstitial cells and their derivatives. The reciprocal experiment of grafting 72-hour epithelial planular tails to 72-hour control labelled planular heads was also done and the tail pieces were examined. Repopulated planular head pieces contained interstitial cells, ganglionic cells and a reforming neural plexus but few nematoblasts/nematocytes. Reconstituted planular tail pieces contained interstitial cells and nematoblasts/nematocytes but no ganglionic cells. Results possibly suggest that the migrating interstitial cell population of 72-hour planulae is rich in committed precursors.     

Two specific populations of GABAergic neurons originating from the medial and the caudal ganglionic eminences aid in proper navigation of callosal axons

The corpus callosum (CC) plays a crucial role in interhemispheric communication. It has been shown that CC formation relies on the guidepost cells located in the midline region that include glutamatergic and GABAergic neurons as well as glial cells. However, the origin of these guidepost GABAergic neurons and their precise function in callosal axon pathfinding remain to be investigated. Here, we show that two distinct GABAergic neuronal subpopulations converge toward the midline prior to the arrival of callosal axons. Using in vivo and ex vivo fate mapping we show that CC GABAergic neurons originate in the caudal and medial ganglionic eminences (CGE and MGE) but not in the lateral ganglionic eminence (LGE). Time lapse imaging on organotypic slices and in vivo analyses further revealed that CC GABAergic neurons contribute to the normal navigation of callosal axons. The use of Nkx2.1 knockout (KO) mice confirmed a role of these neurons in the maintenance of proper behavior of callosal axons while growing through the CC. Indeed, using in vitro transplantation assays, we demonstrated that both MGE‐ and CGE‐derived GABAergic neurons exert an attractive activity on callosal axons. Furthermore, by combining a sensitive RT‐PCR technique with in situ hybridization, we demonstrate that CC neurons express multiple short and long range guidance cues. This study strongly suggests that MGE‐ and CGE‐derived interneurons may guide CC axons by multiple guidance mechanisms and signaling pathways. © 2013 Wiley Periodicals, Inc. Develop Neurobiol 73: 647–672, 2013     

In vitro effects of histamine liberator compound 48/80 on rat superior cervical ganglia with special regard to the small granule-containing cells

Summary The effect of the histamine liberator compound 48/80 on the rat superior cervical ganglia in vitro has been investigated. After incubation of the ganglia with compound 48/80: (1) ganglionic mast cells degranulate in the same manner as in other tissues; (2) cell bodies of the postganglionic neurons are not affected by compound 48/80; (3) there is evidence that ganglionic interneurons, the monoamine-containing cells are activated. The ultrastructural aspects of this process are characterized by degranulation of perikarya and accumulation of dense core vesicles in cell processes and in terminals adjacent to presynaptic membranes. These vesicles vary in size between 200–800 Å in diameter. They may represent storage sites of the neurotransmitter complexes that have undergone exocytosis. The results are discussed with special reference to models of exocytotic processes involving the adrenergic transmitter. It is concluded that monoamine-containing cells represent interneurons in sympathetic ganglia which inhibit ganglionic transmission and which are stimulated by low concentrations of compound 48/80 in vitro.This work was supported by the Deutsche Forschungsgemeinschaft (SFB 70 Hirnforschung).The authors wish to thank Professor Dr. J. Staubesand for his encouragement in the course of this work.Dedicated to Prof. Gian Töndury, Zurich, on the occasion of his 70th birthday.     

Gangliogenesis in leech: morphogenetic processes leading to segmentation in the central nervous system

 Using intracellular lineage tracers to study the main neurogenic lineage (N lineage) of the glossiphoniid leech embryo, we have characterized events leading from continuous columns of segmental founder cells (nf and ns primary blast cells) to discrete, segmentally iterated ganglia. The separation between prospective ganglia was first evident as a fissure between the posterior boundary of nf- and the anterior boundary of ns-derived progeny. We also identified the sublineages of nf-derived cells that contribute parallel stripes of cells to each segment. These stripes of cells project ventrolaterally from the dorsolateral margin of each nascent ganglion to the ventral body wall. The position and orientation of the stripes suggests that they play a role in forming the posterior segmental nerve; they are not coincident with the ganglionic boundary, and they form well after the separation of ganglionic primordia. Previous work has shown that cells in the anterior stripe express the leech engrailed-class gene. Thus, in contrast to the role of cells expressing engrailed in Drosophila, the stripes of N-derived cells expressing an engrailed-class gene in leech do not seem to play a direct role in segmentation or segment polarity. Received: 10 October 1997 / Accepted: 12 December 1997     

Laminin-like immunoreactivity in the snail Helisoma: Involvement of a ∼300 kD extracellular matrix protein in promoting outgrowth from identified neurons

Polyclonal antibodies directed against laminin (LM), and against the A and B chains of reduced LM were used to identify antigenically related proteins in the extracellular matrix (ECM) of the snail Helisoma trivolvis Immunofluorescence of snail central ganglionic rings using either the anti-LM or anti-B chain antibodies labeled the ECM within ganglionic sheaths as well as basal laminae surrounding the ganglia. Both the anti-LM and anti-B chain antibodies recognized a prominent, ～300-kD protein on immunoblots of a snail central ganglion preparation enriched in ECM components. The anti-A chain antibody failed to label any structures in sections of snail ganglia or to recognize any proteins on immunoblots of ganglionic ECM. A polyclonal antibody was raised against the ～300-kD snail protein. Immunofluorescence of snail ganglia with the anti-～300-kD antibody gave a distribution of labeled structures comparable to that obtained with the anti-LM antibody. Immunofluorescent labeling of sections of snail muscle and salivary gland with the anti-～300-kD antibody revealed a distribution of reactive protein characteristic of an ECM component. Probing immunoblots of ganglionic ECM with the anti- ～300-kD antibody revealed the recognition of the same ～ 300-kD protein as identified by the anti-LM antibodies. Media conditioned by Helisoma central ganglionic rings (CM) contains an unidentified neurite outgrowth promoting factor (NOPF). Immunoblots of CM probed with the anti-B chain and anti- ～300-kD antibodies reveal the recognition of a soluble ～300-kD protein similar to the ～300-kD protein identified in snail ECM. The ganglionic ECM preparation containing the ～300-kD protein supported outgrowth from cultured snail buccal neurons B5, and addition of anti- ～300-kD Fab fragments to CM abolished its outgrowth promoting activity. These results suggest that the ～300-kD ECM protein may be the NOPF in CM and /or functions in promoting neurite outgrowth.     

The Morphology of the Stomodeal Nervous System in the Adult Dragon Flies Bradinopyga geminata and Orthetrum chrysis (Libellulidae)

The morphology of the stomodeal nervous system of the adult dragon flies Bradinopyga geminata and Orthetrum chrysis is described. No gastric ganglion or ganglion ingluviale has been found. Instead the oesophageal nerve forks near the junction of the proventriculus and the midgut. The two nerves run on either side of the midline as ingluvial nerves and enter the proventricular ganglionic masses. These ganglionic masses are connected by a transverse nerve, which has been called as the nervus transversus proventriculare. Both bipolar and multipolar types of sensory cells have been found over the surface of the crop. These cell bodies appear to be interconnected by connective tissue. Dendrites of these cells terminate on the longitudinal muscle fibres, surrounding the proventriculus and the midgut. The proximal processes of these cells enter the proventricular ganglionic mass. In methylene blue whole mounts they resemble the stretch receptors, hence it is quite probable that they play some role in the peristaltic movement of the gut. The corpora cardiaca lie dorsal to the pharynx and are connected to the brain by two pairs of nerves, the nervi corporis cardiaci (NCC I, NCC II). Unlike in other insects, the nerve connecting the corpora cardiaca with the corpora allata is slender and arises as a branch of the nerve, nervus corporis allati II. The corpora alata are spherical to ovoid in shape and lie ventral to the nerve cord. Anteriorly they are attached to the inner wall of the hypopharynx and posteriorly to the subesophageal ganglion by a pair of nerves, the nervi corporis allati II.     

The effects of narcotic analgesics and narcotic antagonists on ganglionic transmission in the rat.

The effects of narcotic analgesics, narcotic-antagonist analgesics and narcotic antagonists on ganglionic transmission in the superior cervical ganglia of the rat were studied $\text{in}$$\text{vivo}$ and $\text{in}$$\text{vitro}$. $\text{In}$$\text{vivo}$ administration of morphine, meperidine, methadone, pentazocine or naltrexone blocked ganglionic transmission. Levorphanol, cyclazocine, nalorphine and naloxone had no effect on ganglionic transmission in this procedure. $\text{In}$$\text{vitro}$ studies confirmed the $\text{in}$$\text{vivo}$ results with the exception of levorphanol, cyclazocine and nalorphine, which were also found to block ganglionic transmission $\text{in}$$\text{vitro}$. In both preparations, naloxone did not antagonize the effect of morphine, suggesting that the effects of morphine and the other opiates were nonspecific. Similar potency of $\text{d}$- and $\text{l}$-isomers of pentazocine and cyclazocine support this conclusion. The observation that naltrexone blocked ganglionic transmission, but the other pure narcotic antagonist, naloxone, was inactive is somewhat unique to this test procedure and possibly significant.     

Dopaminergic acceleration and GABAergic inhibition in extrinsic neural control of the hermit crab heart

The acceleratory and inhibitory cardio-regulatory nerves of hermit crabs (Aniculus aniculus, Dardanus crassimanus) were studied using histochemical, immunocytochemical and pharmacological tests. Glyoxylic acid-induced fluorescence was observed in two of three axons of the dorsal cardiac nerve. One axon of the nerve showed gamma-aminobutyric acid-like immunoreactivity. Effects of stimulation of cardio-acceleratory axons were blocked by the dopaminergic antagonists, haloperidol and chlorpromazine, but not by cholinergic, adrenergic or serotonergic blockers, suggesting that dopamine is the primary potential candidate for the neurotransmitter of cardio-accelerator neurons. Picrotoxin antagonized inhibition of the cardiac ganglion induced by gammaam-inobutyric acid and by cardio-inhibitory axons. Both small and large ganglionic cells may receive dopaminergic and GABAergic extrinsic neural control.Abbreviations ACh acetylcholine - CA cardio-accelerator - CA1 and CA2 first and second cardio-accelerators - CI cardio-inhibitor - EJP excitatory junction potential - GABA gamma-aminobutyric acid - EPSP excitatory postsynaptic potential - IPSP inhibitory postsynaptic potential - LGC large ganglionic cell - SGC small ganglionic cell - 5-HT serotonin     

Ultrastructural evidence for the presence of nerve cells in the gastrodermis of Hydra

Summary Two types of nerve cells, namely, neurosensory and neurosecretory cells have been identified and described in the gastrodermis of Hydra pseudoligactis. The morphological criteria used for the identification of gastrodermal nerves are based on those presented previously for epidermal nerves. The third type of nerve cell in the epidermis, ganglionic cells, was not observed in these studies. The distribution, function and origin of gastrodermal nerve cells are discussed briefly.With the technical assistance of Linda M. Bookman.     

A comparative immunocytochemical investigation of the crustacean hyperglycemic hormone (CHH) in the eyestalks of some decapod crustacea

The eyestalk of the astacideans Orconects limosus, Nephrops norvegicus, and Homarus gammarus, and the palinuran Palinurus vulgaris, was examined with an antiserum raised against purified crustacean hyperglycemic hormone (CHH) of the astacidean species Astacus leptodactylus. A distinct immunopositive reaction occurs in a group of neurosecretory cells in the medulla terminalis ganglionic X-organ (MTGX), in the MTGX-sinus gland tractus, and in a considerable part of the sinus gland. The immunoreactive sites in the eyestalk of the investigated species correspond to the site of production, storage, and release of the CHH. Preliminary investigations with this antiserum also indicate that a positive immunoreaction can be obtained in the eyestalk of other decapod crustaceans, for example, of the brachyuran Macropipus puber and the caridean Palaemon serratus.     

Regulation of vasoactive intestinal peptide expression in sympathetic neurons in culture and after axotomy: The role of cholinergic differentiation factor/leukemia inhibitory factor

Vasoactive intestinal peptide (VIP) expression increases in sympathetic neurons when they are grown in dissociated cell or explant cultures and when they are axotomized in vivo. In dissociated cell culture, the magnitude of the VIP increase was reduced when nonneuronal cells were removed and medium conditioned by ganglionic nonneuronal cells increased VIP in neuron-enriched cultures. Antiserum Against cholinergic differentiation factor (also leukemia inhibitory factor; CDF/LIF), but not against ciliary neurotrophic factor, immunoprecipitated this activity. Medium conditioned by sympathetic ganglion explants also contained a VIP-stimulatory molecule that was immunoprecipitated by CDF/LIF antiserum, and CDF/LIF antiserum partially blocked VIP induction in explants. CDF/LIF mRNA was increased in dissociated cell cultures, in ganglion explants and in vivo after axotomy. Our results suggest that CDF/LIF released from ganglionic nonneuronal cells plays an important role in regulating VIP after axotomy. 1994 John Wiley & Sons, Inc.     

Ultrastructure of the synganglion in the larval tickAmblyomma americanum (Ixodoidea: Ixodidae)

The synganglion in the larvalAmblyomma americanum consists of a ganglionic mass pierced by the oesophagus. The nervous tissue consisting of an outer cortex and an inner neuropile is surrounded by an external neurilemma. The cortex comprises perineurium glial cells and neurosecretory and non-neurosecretory neuronal cell bodies. The neuropile consists of nerve fibres ensheathed by glial cells. The entire ganglionic mass is enclosed within a sinus of the circulatory system. No investigations using electron microscopy appear to have been made on the synganglion in the tick larval stage.     

Histamine immunoreactivity in the central nervous system of the spider Cupiennius salei

In this study, immunohistochemistry on Vibracut sections is used to demonstrate anti-histamine immunoreactivity in the brain of the spider, Cupiennius salei (Keys.) (Ctenidae). We describe a system of histamine-immunoreactive neurons within the central nervous system that consists of six omnisegmental neurons. These histamine-immunoreactive neurons form two subgroups: a dorsal system with two cells per hemisphere and a ventral system with only one cell per hemisphere. The cells have extended arborizations in the motor and sensory areas of all neuromeres in the suboesophageal ganglionic mass. We have also found histamine immunoreactivity in the photoreceptors of C. salei and suggest that histamine is a neurotransmitter of photoreceptors in all arthropods, since it is also known to occur in the photoreceptors of the other main arthropod taxa (Merostomata, Crustacea, and Insecta).     

On Mertensiella luschani helverseni populations in Southwestern Anatolia

Abstract

The leech family Barbronidae is distinguished from the Salifidae and Erpobdellidae by the presence of two accessory copulatory pores, and by the ventral nerve cord with 19 free ganglia and 9 ganglia fused to form the posterior ganglionic mass. Some characteristics of Barbronia assiuti are revised, such as the presence of stylets and the annulation.