Pentylenetetrazol-induced seizures affect the levels of prolyl oligopeptidase, thimet oligopeptidase and glial proteins in rat brain regions, and attenuation by MK-801 pretreatment

Neurochem Int. 2005 Sep;47(4):248-59. doi: 10.1016/j.neuint.2005.04.025.

Abstract

The regulatory mechanisms of neuropeptide-metabolizing enzymes often play a critical role in the pathogenesis of neuronal damage. A systemic administration of pentylenetetrazol (PTZ), an antagonist of GABA(A) receptor ion channel binding site, causes generalized epilepsy in an animal model. In the present study, we examined the involvement of prolyl oligopeptidase (POP), thimet oligopeptidase/neurolysin (EP 24.15/16) and glial proteins in PTZ-treated rat brain regions, and the suppressive effect of MK-801, a non-competitive NMDA receptor antagonist, pretreatment for their proteins. The activity of POP significantly decreased in the hippocampus at 30min and 3h, and in the frontal cortex at 3h after PTZ treatment, and pretreatment with MK-801 recovered the activity in the cortex at 3h. The activity of EP 24.15/16 significantly decreased in the hippocampus at 3h and 1 day, and in the cortex at 3h after the PTZ administration, whereas pretreatment with MK-801 recovered the change of the activity. The Western blot analysis of EP 24.15 showed significant decrease of the protein level in the hippocampus 3h after the PTZ treatment, whereas pretreatment with MK-801 recovered. The expression of GFAP and CD11b immunohistochemically increased in the hippocampus of the PTZ-treated rat as compared with controls. Pretreatment with MK-801 also recovered the GFAP and CD11b expression. These data suggest that PTZ-induced seizures of the rats cause indirect activation of glutamate NMDA receptors, then decrease POP and EP 24.15/16 enzyme activities and EP 24.15 immunoreactivity in the neuronal cells of the hippocampal formation. We speculate that changes of those peptidases in the brain may be related to the levels of the neuropeptides regulating PTZ-induced seizures.

MeSH terms

  • Animals
  • Brain / drug effects
  • Brain / metabolism*
  • Brain / physiopathology
  • CD11b Antigen / drug effects
  • CD11b Antigen / metabolism
  • Cerebral Cortex / drug effects
  • Cerebral Cortex / metabolism
  • Cerebral Cortex / physiopathology
  • Convulsants
  • Disease Models, Animal
  • Dizocilpine Maleate / pharmacology*
  • Dizocilpine Maleate / therapeutic use
  • Down-Regulation / drug effects
  • Down-Regulation / physiology
  • Epilepsy / chemically induced
  • Epilepsy / drug therapy
  • Epilepsy / physiopathology*
  • Excitatory Amino Acid Antagonists / pharmacology
  • Excitatory Amino Acid Antagonists / therapeutic use
  • GABA Antagonists / pharmacology
  • Glial Fibrillary Acidic Protein / drug effects
  • Glial Fibrillary Acidic Protein / metabolism*
  • Hippocampus / drug effects
  • Hippocampus / metabolism
  • Hippocampus / physiopathology
  • Male
  • Metalloendopeptidases / drug effects
  • Metalloendopeptidases / metabolism*
  • Nerve Degeneration / drug therapy
  • Nerve Degeneration / metabolism
  • Nerve Degeneration / prevention & control
  • Neuroglia / drug effects
  • Neuroglia / metabolism
  • Neuroglia / pathology
  • Neurons / drug effects
  • Neurons / metabolism
  • Neurons / pathology
  • Pentylenetetrazole
  • Prolyl Oligopeptidases
  • Rats
  • Rats, Wistar
  • Receptors, N-Methyl-D-Aspartate / agonists
  • Receptors, N-Methyl-D-Aspartate / metabolism
  • Serine Endopeptidases / drug effects
  • Serine Endopeptidases / metabolism*

Substances

  • CD11b Antigen
  • Convulsants
  • Excitatory Amino Acid Antagonists
  • GABA Antagonists
  • Glial Fibrillary Acidic Protein
  • Receptors, N-Methyl-D-Aspartate
  • Dizocilpine Maleate
  • Serine Endopeptidases
  • Prolyl Oligopeptidases
  • Metalloendopeptidases
  • thimet oligopeptidase
  • Pentylenetetrazole