Enhanced anticonvulsant activity of neuroactive steroids in a rat model of catamenial epilepsy

Doodipala S. Reddy, Michael A Rogawski

Research output: Contribution to journalArticlepeer-review

103 Scopus citations

Abstract

Purpose: Perimenstrual catamenial epilepsy may in part be due to withdrawal of the endogenous progesterone-derived neurosteroid allopregnanolone that potentiates γ-aminobutyric acidA (GABAA) receptor-mediated inhibition. Here we sought to determine whether the anticonvulsant potencies of neuroactive steroids, benzodiazepines, phenobarbital (PB), and valproate (VPA) are altered during the heightened seizure susceptibility accompanying neurosteroid withdrawal in a rat model of perimenstrual catamenial epilepsy. Methods: Test drugs were evaluated for their ability to alter the convulsant activity of pentylenetetrazol (PTZ) in young adult female rats, in pseudopregnant rats with prolonged exposure to high levels of progesterone (and its neurosteroid metabolites), and in pseudopregnant rats 24 h after acute withdrawal of neurosteroids by treatment with the 5α-reductase inhibitor finasteride. Test drugs were administered at doses equivalent to twice their ED50 values for protection against PTZ-induced clonic seizures in naive young adult female rats. Results: The anticonvulsant activity of allopregnanolone (5 mg/kg, s.c.), pregnanolone (5 mg/kg, s.c.), allotetrahydrodeoxycorticosterone (15 mg/kg, s.c.), and tetrahydrodeoxycorticosterone (10 mg/kg, s.c.) were enhanced by 34-127% after neurosteroid withdrawal. The anticonvulsant activity of PB (65 mg/kg, i.p.) was also enhanced by 24% in neurosteroid-withdrawn animals. In contrast, the anticonvulsant activity of diazepam (4 mg/kg, i.p.), bretazenil (0.106 mg/kg, i.p.), and VPA (560 mg/kg, i.p.) were reduced or unchanged in neurosteroid-withdrawn animals. Conclusions: The anticonvulsant activity of neuroactive steroids is potentiated after neurosteroid withdrawal, supporting the use of such agents in the treatment of perimenstrual catamenial epilepsy.

Original languageEnglish (US)
Pages (from-to)337-344
Number of pages8
JournalEpilepsia
Volume42
Issue number3
DOIs
StatePublished - 2001
Externally publishedYes

Keywords

  • Benzodiazepam
  • Bretazenil
  • Catamenial epilepsy
  • Neurosteroid
  • Phenobarbital
  • Valproate

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)

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