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Role Of Neurosteroids In The Anticonvulsant Activity Of Midazolam, Ashish Dhir, Michael A. Rogawski
Role Of Neurosteroids In The Anticonvulsant Activity Of Midazolam, Ashish Dhir, Michael A. Rogawski
Michael A. Rogawski
BACKGROUND AND PURPOSE Midazolam is a short-acting benzodiazepine that is widely used as an intravenous sedative and anticonvulsant. Besides interacting with the benzodiazepine site associated with GABA-A receptors, some benzodiazepines act as agonists of translocator protein (18 kDa) (TSPO) to enhance the synthesis of steroids, including neurosteroids with positive modulatory actions on GABA-A receptors. We sought to determine if neurosteroidogenesis induced by midazolam contributes to its anticonvulsant action. EXPERIMENTAL APPROACH Mice were pretreated with neurosteroid synthesis inhibitors and potentiators followed by midazolam or clonazepam, a weak TSPO ligand. Anticonvulsant activity was assessed with the intravenous pentylenetetrazol (PTZ) threshold test. KEY …
11beta-Hydroxylase Inhibitors Protect Against Seizures In Mice By Increasing Endogenous Neurosteroid Synthesis, Rafal Kaminski, Michael Rogawski
11beta-Hydroxylase Inhibitors Protect Against Seizures In Mice By Increasing Endogenous Neurosteroid Synthesis, Rafal Kaminski, Michael Rogawski
Michael A. Rogawski
Steroid 11β-hydroxylase (CYP11B1; EC 1.14.15.4) is a mitochondrial enzyme located in the zona fasciculata of the adrenal cortex and also in the brain that mediates the conversion of 11-deoxycortisol to cortisol and 11-deoxycorticosterone (DOC) to corticosterone. Inhibitors of CYP11B1, such as metyrapone and etomidate, reduce glucocorticoid synthesis and raise levels of DOC providing greater availability for metabolic conversion to the GABA-A receptor modulating neurosteroid allotetrahydrodeoxycorticosterone (THDOC). Because THDOC is potent anticonvulsant, it is plausible that CYP11B1 inhibitors could protect against seizures. Here we demonstrate that metyrapone affords dose-dependent protection against 6-Hz seizures 30 min after injection (ED50, 191 mg/kg), but …