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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 84 (1973), S. 267-279 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The electrical activity of the heart nerve and of single neurons in the suboesophageal ganglia were recorded during tactile stimulation of the heart. 15 neurons were identified which responded to heart stimulation by inhibiting or accelerating activity. Cells influenced by heart afferents are scattered in the visceral and in the right and left parietal ganglia. In most of the cases both decrease and increase of cell activity are caused by synaptic potentials, in some cases, however, the neuron is assumed to have a sensory character. The activity of three neurons influenced by heart stimulation was conducted into the heart nerve. These cells are central neurons of a heart-CNS-heart reflex. Some of the neurons located in the right parietal and visceral ganglia have no connection with the mechanoreceptors of the heart. Since their spikes propagate into the heart nerve, they probably take part in the extracardial regulation of heart activity. One of the neurons located in the visceral ganglion (cell V12) sends its axon into the heart nerve. The response of this neuron to heart stimulation was an increase in activity and an inhibition of the heart rate. This is an inhibitory neuron of the extracardial heart regulatory system.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular neurobiology 4 (1984), S. 199-206 
    ISSN: 1573-6830
    Keywords: adenylate cyclase ; octopamine ; dopamine ; insect brain ; metamorphosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Octopamine- and dopamine-sensitive adenylate cyclases were studied in the brain ofLocusta migratoria during its metamorphosis. In the adult brain the effects of octopamine and dopamine on adenylate cyclase were additive, suggesting the presence of separate populations of adenylate cyclase-linked receptors for octopamine and dopamine. There are no separate receptors for noradrenaline. 2. Octopamine stimulates adenylate cyclase in both adult and larval brain; however, in adult brain octopamine is more potent than in larval brain. Dopamine stimulates adenylate cyclase activity only in adult brain. The sensitivity of adenylate cyclase to octopamine changes during the development of the animal. 3. Phentolamine and cyproheptadine are potent antagonists of octopaminestimulated adenylate cyclase, while propanolol has a weak effect. 4. No cytosol factor which would modulate either basal or octopaminestimulated adenylate cyclase was found. 5. The effect of GTP and octopamine on adenylate cyclase was synergistic in adult brain but not in larval brain, while the effect of GppNHp and octopamine was synergistic in both adult and larval brains.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular neurobiology 14 (1994), S. 735-754 
    ISSN: 1573-6830
    Keywords: mercury ; lead ; zinc ; Helix pomatia L. ; Lymnaea stagnalis L. ; identified neurons ; synaptic transmission ; heavy metal toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The effects of heavy metals (Pb2+, Hg2+, and Zn2+) on synaptic transmission in the identified neural network ofHelix pomatia L. andLymnaea stagnalis L. (Gastropoda, Mollusca) were studied, with investigation of effects on inputs and outputs as wells as on interneuronal connections. 2. The sensory input running from the cardiorenal system to the central nervous system and the synaptic connections between central neurons were affected by heavy metals. 3. Lead and mercury (10−5−10−3 M) eliminated first the inhibitory, then the excitatory inputs running from the heart to central neurons. At the onset of action lead increased the amplitude of the excitatory postsynaptic potentials, but blockade of sensory information transfer occurred after 10–20 min of treatment. 4. The monosynaptic connections between identified interneurons were inhibited by lead and mercury but not by zinc. Motoneurons were found to be less sensitive to heavy metal treatment than interneurons or sensory pathways. 5. The treatment with Pb2+ and Hg2+ often elicited pacemaker and bursting-type firing in central neurons, accompanied by disconnection of synaptic pathways, manifested by insensitivity to sensory synaptic influences. 6. Zn2+ treatment also sometimes induced pacemaker activity and burst firing but did not cause disconnection of the synaptic transmission between interneurons. 7. A network analysis of heavy metal effects can be a useful tool in understanding the connection between their cellular and their behavioral modulatory influences.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Environmental monitoring and assessment 14 (1990), S. 363-375 
    ISSN: 1573-2959
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The interaction of heavy metals (HgCl2, CdCl2, CuCl2, PbCl2 and ZnCl2) and neurotransmitters (ACh, 5HT and DA) was studied on the excitable membrane of identified neurons of Lymnaea stagnalis and Helix pomatia. It was shown that, (1) The excitability and chemosensitivity of molluscan neurons were modified under the influence of the heavy metals Hg2+, Cd2+, Cu2+, Pb2+ and Zn2+. (2) Change in excitability to transmitters occurred as a potentiation or depression of the evoked response both in duration of membrane polarization and in frequency of spike activity. (3) The chemosensitivity changes in various ways, namely: excitatory effect was totally eliminated; one component of the effect was depressed. Different neurons may show different reactions to the same heavy metal. (4) There were differences in the effects of various heavy metals. Hg2+ has a more generalized effect than Cd2+; Cu2+, Pb2+ and Zn2+ were less effective in a number of neurons. The heavy metal effect was dose dependent, too. (5) Both inward and outward currents, which were evoked by neurotransmitters or voltage induced, were modified in most of the tested neurons. Both an increase and decrease of the membrane permeability occurred in different neurons in response to the same or different heavy metals. (6) The changes can be interpreted as a result of direct effect on specific ionic channels; modification of receptors binding ACh, 5HT, or DA; modification of intracellular processes responsible for the regulation of membrane permeability.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0878
    Keywords: Serotonin (5HT) ; Immunocytochemistry ; 5,6-Dihydroxytryptamine ; Central nervous system ; Helix pomatia (Mollusca)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of serotonin (5HT)-containing neurons in the central nervous system of the snail Helix pomatia has been determined in whole-mount preparations by use of immunocytochemical and in vivo 5,6-dihydroxy-tryptamine labelling. 5HT-immunoreactive neuronal somata occur in all but the buccal and pleural ganglia. Immunoreactive fibres are present throughout the central nervous system. The 5HT-immunoreactive neuronal somata characteristically appear in groups, located mainly in the cerebral, pedal, visceral and right parietal ganglia. The majority of 5HT-immunoreactive neurons is located in the pedal ganglia. Additionally a dense network of 5HT-immunoreactive varicose fibres is found in the neural sheath of the central nervous system including all the nerves and ganglia. The number and distribution of 5HT-immunoreactive neurons correlates with that demonstrated by 5,6-dihydroxytryptamine labelling method.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0878
    Keywords: Synapses ; Intestinal nerve ; Ultrastructure ; Helix pomatia ; Horseradish peroxidase technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of nerve cells and the finestructural organization of synaptic contacts have been investigated in the intestinal nerve in the snail Helix pomatia. Three types of nerve cells, occurring singly or in groups, can be distinguished on the basis of the ultrastructure of their perikaryon and content of granules. The peripheral output of these nerve cells has been verified by retrograde CoCl2 and NiCl2 staining. Both axosomatic and axo-axonic specialized synaptic contacts occur in the intestinal nerve. Presynaptic elements of these synaptic contacts contain 100–120 nm granular vesicles or 120–200 nm neurosecretory-like granules. Following intracellular horseradish peroxidase (HRP) labelling of identified central neurons responsible for peripheral regulatory processes, several labelled axons running toward the periphery can be followed throughout the branches of the intestinal nerve. These labelled axon processes (either primary axon or small collaterals) form specialized synaptic contacts, inside the intestinal nerve, and are always in a postsynaptic position. The occurrence of peripheral axo-somatic and axo-axonic synapses provides a morphological basis for integrative processes taking place in the intestinal nerve (peripheral nervous system) of Helix pomatia.
    Type of Medium: Electronic Resource
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