Modulation of synaptic events by heavy metals in the central nervous system of mollusks

Katalin S.-Rózsa, János Salánki

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Abstract

1. The effects of heavy metals (Pb2+, Hg2+, and Zn2+) on synaptic transmission in the identified neural network of Helix pomatia L. and Lymnaea 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 (10-5-10-3M) 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.

Original languageEnglish
Pages (from-to)735-754
Number of pages20
JournalCellular and Molecular Neurobiology
Volume14
Issue number6
DOIs
Publication statusPublished - Dec 1 1994

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Keywords

  • Helix pomatia L.
  • Lymnaea stagnalis L.
  • heavy metal toxicity
  • identified neurons
  • lead
  • mercury
  • synaptic transmission
  • zinc

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience
  • Cell Biology

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