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Neurosteroids and epileptogenesis in the pilocarpine model: evidence for a relationship between P450scc induction and length of the latent period.
- Source :
-
Epilepsia [Epilepsia] 2009 Jan; Vol. 50 Suppl 1, pp. 53-8. - Publication Year :
- 2009
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Abstract
- Purpose: Cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc) catalyzes the initial step in the biosynthesis of neurosteroids within the brain. We sought to determine which cells express P450cc and whether neurosteroids play a role in the regulation of epileptogenesis following pilocarpine-induced status epilepticus (SE).<br />Methods: Rats experienced uninterrupted SE or SE terminated with diazepam at 60, 120, and 180 min. P450scc induction in CA3 hippocampus was determined by double immunolabeling with P450scc antiserum and monoclonal antibodies against GFAP (astrocytes), RIP (oligodendrocytes), or heme oxygenase-1 (microglia).<br />Results: SE was associated with P450scc induction in many astrocytes and a small number of microglia and oligodendrocytes in the hippocampal CA3 strata radiatum and lacunosum-moleculare. The extent of P450scc induction increased with increasing SE duration. Paradoxically, increased P450scc induction in rats experiencing SE for 180 min or more was associated with the delayed onset of spontaneous recurrent seizures. Treatment with the 5 alpha-reductase inhibitor finasteride (100 mg/kg/day for 25 days), which inhibits the synthesis of gamma-aminobutyric acid (GABA)(A) receptor modulating neurosteroids such as allopregnanolone, was associated with a significant reduction in time to the onset of spontaneous seizures in rats exposed to 180-min but not 90-min SE.<br />Discussion: P450scc is induced by SE in a diverse population of hippocampal glia. Induction of P450scc is associated with the delayed onset of spontaneous seizures. Conversely, inhibition of neurosteroid synthesis accelerated the onset of spontaneous seizures, but only in animals exhibiting significant increases in P450scc. These findings suggest that induction of neurosteroid synthesis in reactive glial cells is associated with delayed onset of spontaneously recurrent seizures.
- Subjects :
- Animals
Cholesterol Side-Chain Cleavage Enzyme physiology
Enzyme Induction drug effects
Enzyme Induction physiology
Male
Neurotransmitter Agents physiology
Rats
Rats, Sprague-Dawley
Reaction Time drug effects
Receptors, GABA-A biosynthesis
Receptors, GABA-A physiology
Recurrence
Seizures enzymology
Seizures metabolism
Seizures physiopathology
Status Epilepticus chemically induced
Status Epilepticus metabolism
Cholesterol Side-Chain Cleavage Enzyme biosynthesis
Disease Models, Animal
Neurotransmitter Agents biosynthesis
Pilocarpine toxicity
Reaction Time physiology
Status Epilepticus enzymology
Subjects
Details
- Language :
- English
- ISSN :
- 1528-1167
- Volume :
- 50 Suppl 1
- Database :
- MEDLINE
- Journal :
- Epilepsia
- Publication Type :
- Academic Journal
- Accession number :
- 19125849
- Full Text :
- https://doi.org/10.1111/j.1528-1167.2008.01971.x