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Pflügers Archiv - European Journal of Physiology

, Volume 470, Issue 8, pp 1221–1230 | Cite as

Methylmercury reduces synaptic transmission and neuronal excitability in rat hippocampal slices

  • J. Gutiérrez
  • A. M. Baraibar
  • E. Albiñana
  • P. Velasco
  • J. M. Solís
  • J. M. Hernández-Guijo
Ion channels, receptors and transporters
  • 109 Downloads
Part of the following topical collections:
  1. Ion channels, receptors and transporters

Abstract

In a previous study, we pointed out that the neurotoxic action evoked by methylmercury (MeHg), a potent environmental pollutant responsible for fatal food poisoning, is associated with alterations of cellular excitability by irreversible blockade of sodium and calcium currents. Here, we investigated the MeHg effects on synaptic transmission and neuronal plasticity using extracellular field recording in CA1 area of rat hippocampal slices. MeHg caused a fast and drastic depression of evoked field excitatory postsynaptic potentials (fEPSPs) in a concentration-dependent manner with an IC50 of 25.7 μM. This depression was partially caused by the irreversible reduction of axon recruitment deduced from the decrement of the fiber volley (FV) amplitude. Nevertheless, this MeHg-induced synaptic depression represents a true reduction of synaptic efficacy, as judged by input/output curves. In addition, a reduction on presynaptic release of glutamate was detected with the paradigm of paired-pulse facilitation during MeHg application. Moreover, MeHg also reduced population spike (PS) ampxlitude, and this effect was more prominent when the PS was evoked by ortodromic stimulation than by antidromic stimulation. Interestingly, despite these strong effects of MeHg on synaptic transmission and excitability, this compound did not modify the induction of long-term synaptic potentiation (LTP). The effects described here for MeHg were irreversible or very slowly reversible after drug wash-out. In summary, the blockade of sodium and calcium channels by MeHg affects synaptic transmission and cellular excitability but not synaptic plasticity.

Keywords

Synaptic transmission fEPSP Population spikes Hippocampal slices Methylmercury Intrinsic excitability 

Notes

Acknowledgements

G.J. is a fellow of MEC. E.A. is a fellow of FTH. The authors gratefully acknowledge the technical assistance of José Barbado.

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • J. Gutiérrez
    • 1
    • 2
  • A. M. Baraibar
    • 1
    • 2
  • E. Albiñana
    • 1
    • 2
  • P. Velasco
    • 1
  • J. M. Solís
    • 3
  • J. M. Hernández-Guijo
    • 1
    • 2
  1. 1.Department of Pharmacology and TherapeuticUniversidad Autónoma de Madrid, IRYCISMadridSpain
  2. 2.Instituto Teófilo Hernando, Facultad de Medicina, Departamento de FarmacologíaUniversidad Autónoma de Madrid, IRYCISMadridSpain
  3. 3.Servicio de Neurobiología-InvestigaciónHospital Universitario Ramón y Cajal, IRYCISMadridSpain

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