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Bicuculline-induced epileptogenesis in the human neocortex maintained in vitro

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Summary

Intracellular and extracellular recordings were made from human neocortical slices of the temporal lobe maintained in vitro. The slices were treated with bicuculline methiodide to reduce synaptic inhibition mediated by tha gamma-aminobutyric acid A (GABAA) receptor. Spontaneously occurring epileptiform activity was never observed in over 60 slices examined. All epileptiform discharges were elicited by single-shock stimuli delivered in the underlying white matter or within the cortical layers. Intracellularly, the stimulus-induced epileptiform discharge resembled the paroxysmal depolarization shift (PDS). This potential was observed in neurons located between 200 and 2200 μm from the pia. It was characterized by a 100–1800 ms long depolarization which triggered burst firing of action potentials, and was at times followed by an afterdischarge. Simultaneous intracellular and extracellular recordings showed that each PDS was reflected by the synchronous discharge of a neuronal aggregate. The voltage behaviour of the PDS and its preceding EPSP was analyzed in cells that were injected with the lidocaine derivative QX-314. The amplitudes of the PDS depolarizing envelope measured at its peak and during its falling phase both behaved as a monotonic function of the membrane potential by increasing in amplitude during hyperpolarization. In addition, the PDS peak amplitude showed a much greater rate of increase than the early EPSP peak amplitude, thus suggesting that the synaptic conductance underlying the PDS was much greater. Perfusion of the neocortical slices with the N-Methyl-D-aspartate (NMDA) receptor antagonist DL-2-amino-phosphonovaleric acid (APV) reduced both the duration and the amplitude of the paroxysmal field discharge in a dose related fashion. The effects of APV were reflected intracellularly by an attenuation of the PDS's late phase and a blockade of the afterdischarge. Similar findings were also obtained by using the NMDA receptor antagonist 3-((±)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid. These data indicate that reduction or blockade of the GABAA receptor is sufficient to elicit epileptiform discharges in the human neocortex maintained in vitro. Mechanisms dependent upon the NMDA receptor contribute to this type of epileptiform response mainly by prolonging the stimulus-induced depolarizing potential and the associated burst of firing.

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References

  1. Avoli M (1986) Inhibitory potentials in neurons of the deep layers of the “in vitro” neocortical slice. Brain Res 370:165–170

  2. Avoli M (1988) GABAergic mechanisms and epileptic discharges. In: Avoli M, Reader TA, Dykes RW, Gloor P (eds) Neurotransmitter and cortical function: from molecules to mind. Plenum Press, New York, pp 187–205

  3. Avoli M, Louvel J, Pumain R, Olivier A (1987) Seizure-like discharges induced by lowering [Mg2+]0 in the human epileptogenic neocortex maintained in vitro. Brain Res. 417:199–203

  4. Avoli M, Olivier A (1986) Depression of bursting activity in the human epileptogenic neocortex by a N-methyl-D-aspartate antagonist. Soc Neurosci Abstr 12:675

  5. Avoli M, Olivier A (1987) Bursting in human epileptogenic neocortex is depressed by an N-methyl-D-aspartate antagonist. Neurosci Lett 76:249–254

  6. Avoli M, Olivier A (1989) Electrophysiological properties and synaptic responses in the deep layers of the human epileptogenic neocortex in vitro. J Neurophysiol 61:589–606

  7. Ayala GF, Dichter M, Gumnit RJ, Matsumoto H, Spencer WA (1973) Genesis of epileptic interictal spikes: new knowledge of cortical feedback systems suggests a neurophysiological explanation of brief paroxysms. Brain Res 52:1–17

  8. Baldino F Jr., Wolfson B, Heinemann U, Gutnick MJ (1986) An N-methyl-D-aspartate (NMDA) receptor antagonist reduces bicucullineinduced depolarization shifts in neocortical explant cultures. Neurosci Lett 70:101–105

  9. Connors BW (1984) Initiation of synchronized neuronal bursting in neocortex. Nature 310:685–687

  10. Connors BW, Prince DA (1982) Effects of local anaesthetic QX-314 on the membrane properties of hippocampal pyramidal neurons. J Pharmacol Exp Ther 220:476–481

  11. Crill WE, Schwindt PC (1986) Role of persistent inward and outward membrane currents in epileptiform bursting in mammalian neurons. In: Delgado-Escueta AV, Ward AA Jr, Woodbury DM, Porter RJ (eds) Advances in neurology, Vol 44. Raven Press, New York, pp 225–233

  12. Croucher MJ, Collins JF, Meldrum BS (1982) Anticonvulsant action of excitatory amino acid antagonists. Science 216:899–901

  13. Dingledine R, Hynes MA, King GL (1986) Involvement of N-methyl-D-aspartate receptors in epileptiform bursting in the rat hippocampal slice. J Physiol (Lond) 380:175–189

  14. Flatman JA, Schwindt PC, Crill WE, Stafstrom CE (1983) Multiple actions of N-methyl-D-aspartate on cat neocortical neurons in vitro. Brain Res. 266:169–173

  15. Gutnick MJ, Connors BW, Prince DA (1982) Mechanisms of neocortical epileptogenesis in vitro. J Neurophsiol 48:1321–1335

  16. Gutnick MJ, Connors BW, Ransom BR (1981) Dye-coupling between glial cells in the guinea pig neocortical slices. Brain Res 213:486–492

  17. Hablitz JJ, Langmoen IA (1986) N-methyl-D-aspartate receptor antagonists reduce synaptic excitation in the hippocampus. J Neurosci 6:102–106

  18. Herron CE, Williamson R, Collingridge GL (1985) A selective N-methyl-D-aspartate antagonist depresses epileptiform activity in rat hippocampal slices. Neurosci Lett 61:255–260

  19. Hwa GGC, Avoli M (1989) NMDA receptor antagonists CPP and MK-801 partially suppress the epileptiform discharges induced by the convulsant drug bicuculline in the rat neocortex. Neurosci Lett 98:189–193

  20. Johnston D, Brown TH (1981) Giant synaptic potential hypothesis for epileptiform activity. Science 211:294–297

  21. Jones RSG (1988) Epileptiform events induced by GABA-antagonists in entorhinal cortical cells in vitro are partly are mediated by N-methyl-D-aspartate receptors. Brain Res 457:113–121

  22. Kelly JS, Krnjevic K, Yim GKW (1967) Unresponsive cells in cerebral cortex. Brain Res 6:767–769

  23. Kemp JA, Foster AC, Wong EHF (1987) Non-competitive antagonists of excitatory amino acid receptors. Trends Neurosci 10:294–298

  24. Köhr G, Heinemann U (1989) Effects of NMDA antagonists on picrotoxin-, low Mg2+ — and low Ca2+-induced epileptogenesis and on evoked changes in extracellular Na+ and Ca2+ concentrations in rat hippocampal slices. Epilepsy Res 4:187–200

  25. Lacaille JC, Hwa GGC, Avoli M (1988) Electrophysiological properties of neurons in the superficial layers of human temporal neocortex. Soc Neurosci Abstr 14:882

  26. Mayer ML, Westbrook GL, Guthrie PB (1984) Voltage-dependent block of Mg2+ of NMDA responses in spinal cord neurones. Nature 309:261–263

  27. Monaghan DT, Bridges RJ, Cotman CW (1989) The excitatory amino acid receptors: their classes, pharmacology, and distinct properties in the function of the central nervous system. Ann Rev Pharmacol Toxicol 29:365–402

  28. Monaghan DT, Cotman CW (1985) Distribution of N-methyl-D-aspartate-sensitive L-[3H]glutamate-binding sites in rat brain. J Neurosci 5:2909–2919

  29. Nowak L, Bregestovski P, Ascher P, Herbet A, Prochiantz A (1984) Magnesium gates glutamate-activated channels in mouse central neurones. Nature 307:462–465

  30. Prince DA, Connors BW (1986) Mechanisms of interictal epileptogenesis. In: Delgado-Escueta AV, Ward AA Jr, Woodbury DM, Porter RJ (eds) Advances in neurology, Vol 44. Raven Press, New York, pp 275–299

  31. Pumain R, Kurcewicz I, Louvel J (1983) Fast extracellular calcium transients: involvement in epileptic processes. Science 222:177–179

  32. Ransom BR, Goldring S (1973a) Ionic determinants of membrane potential of cells presumed to be glia in cerebral cortex of cat. J Neurophysiol 36:855–868

  33. Ransom BR, Goldring S (1973b) Slow depolarization in cells presumed to be glia in cerebral cortex of cat. J Neurophysiol 36:869–878

  34. Schwartzkroin PA, Haglund MM (1986) Spontaneous rhythmic synchronous activity in epileptic human and normal monkey temporal lobe. Epilepsia 27:523–533

  35. Schwartzkroin PA, Turner DA, Knowles WD, Wyler AR (1983) Studies of human and monkey “epileptic” neocortex in the in vitro slice preparation. Ann Neurol 13:249–257

  36. Sutor B, Hablitz JJ (1989) EPSPs in rat neocortical neurons in vitro. II. Involvement of N-methyl-D-aspartate receptors in the generation of epsps. J Neurophysiol 61:621–634

  37. Thomson AM (1986a) A magnesium-sensitive post-synaptic potential in rat cerebral cortex resembles neuronal responses to N-methylaspartate. J Physiol (London) 370:531–549

  38. Thomson AM (1986b) Comparison of responses to transmitter candidates at an N-methylspartate receptor mediated synapse, in slices of rat cerebral cortex. Neuroscience 17:37–47

  39. Tzachtenberg MC, Pollen DA (1970) Neuroglia: biophysical properties and physiologic function. Science 167:1248–1251

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Correspondence to M. Avoli.

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Hwa, G.G.C., Avoli, M., Oliver, A. et al. Bicuculline-induced epileptogenesis in the human neocortex maintained in vitro. Exp Brain Res 83, 329–339 (1991). https://doi.org/10.1007/BF00231156

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Key words

  • Epilepsy
  • N-methyl
  • D-aspartate
  • Human cortex