title: Functional and morphological changes in the hippocampal neuronal circuits associated with epileptic seizures.
abstract: OBJECTIVE
  We review what is currently known about functional and morphologic plasticity of hippocampal neuronal circuits in animal epilepsy models.
  
  
  RESULTS
  Perforant-path kindling has been shown to enhance excitatory synaptic transmission in the dentate gyrus significantly, and this enhancement has lasted for > or =1 month after kindling. However, in our rapid kindling experiment with an interstimulus interval of 5 min, perforant-path kindling resulted in behavioral convulsions and prolonged the afterdischarge duration, but dentate synaptic transmission remained depressed during kindling.
  
  
  CONCLUSIONS
  These results indicate that kindling-induced synaptic potentiation is not necessary for kindling development. Conversely, epileptic seizures have led to the anomalous sprouting of mossy fibers, a process thought to induce hyperexcitation of granule cells. We conclude that the sprouting of mossy fibers did not play a critical role in kindling, because we observed no significant correlation between the mossy fiber sprouting and kindling development. Epileptic seizures also have been shown to increase gamma-aminobutyric acid (GABA)A receptor-mediated inhibition during interictal periods. Although this strengthening of GABAergic inhibition is likely to be a defensive measure against seizure initiation, some studies have suggested that another type of GABAergic response facilitates seizure activity. The possibility of GABAA receptor-mediated excitation during ictal periods is theoretically examined.
authors.affiliation: Department of Physiology, Nippon Medical School, Tokyo, Japan. emaru@mns.ac.jp
authors.forename: Eiichi
authors.initials: E
authors.lastname: Maru
authors.forename: Masutaro
authors.initials: M
authors.lastname: Kanda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ashida
mesh_terms: D000818:Animals; D018891:Dentate Gyrus / Q000166:cytology / Q000473:pathology / Q000502:physiology; D004195:Disease Models, Animal; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D006624:Hippocampus / Q000473:pathology* / Q000503:physiopathology*; D006801:Humans; D007696:Kindling, Neurologic / Q000502:physiology*; D017774:Long-Term Potentiation; D019599:Mossy Fibers, Hippocampal / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D051381:Rats; D011963:Receptors, GABA-A / Q000502:physiology; D012044:Regression Analysis; D012640:Seizures / Q000473:pathology / Q000503:physiopathology*; D009435:Synaptic Transmission / Q000502:physiology; D013997:Time Factors; D005680:gamma-Aminobutyric Acid / Q000502:physiology
chemical_list: D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid