Neuroactive steroids and their role in epilepsy.

Neuroactive steroids are the certain steroids that alter neuronal excitability via the cell surface through interaction with certain neurotransmitter receptors. Neuroactive steroids regulate physiological functions of the central nervous system and have possible therapeutic potential in neurological diseases. They have been shown to affect neuronal excitability via their interaction with the ligand-gated ion channel family, such as the GABAA receptor by acting genomically as well as nongenomically. Positive modulators of GABAA receptor have anticonvulsant action as they enhance GABAergic transmission thereby increasing the seizure threshold. By virtue of these properties, neurosteroids appear to be relevant to pathophysiology and pharmacological treatment of many neurological diseases including catamenial epilepsy, stress induced epilepsy, temporal lobe epilepsy, alcohol withdrawal seizures, infantile spasm and status epilepticus. So far, only synthetic neurosteroid, ganaxolone has been tried in treatment of epilepsy and has shown good efficacy and tolerability. But, human data of trials are limited and hence, large double-blinded, placebo-controlled, randomized clinical trials are required before their use. The paper reviews the biosynthesis and GABAA receptor modulation of neurosteroids and their potential role in epilepsy.

The Effect of Neuroactive Steroids on the GAVA-Benzodiazepine Receptor Complex / 대한정신약물학회지

Pregnolone[5beta-pregnan-3alpha-ol-one(5beta3alpha)] and allopregnanolone [(5alpha-pregnan-3alpha-ol-20-one(5alpha3alpha))] are neuroactive steroids that are reduced metabolites of progesterone. It was reported that Neuroactive steroids may have anxiolytic and anticonvulsant action similar to benzodiazepines and barbiturates. Therefore, the present study was designed to assess the interaction of steroids with GABAA-benzodiazepine receptor complex. The effect of steroids on the ligands binding to GABAA receptor complex was investigated using rat cortices. 5beta3alpha and 5alpha3alpha enhanced the binding of [3H] flunitrazepam to GABAA receptor, but testosterone, progesterone and dexamethasone did not. GABA also showed the enhancement of [3H] flunitrazepam binding, but did not show the additive effect. Unlike to GABA, 5beta3alpha and 5alpha3alpha did not affect on the [3H] muscimol binding to rat cortices. From these findings, it can be concluded that Neuroactive steroids are potent positive modulators of the GABA A receptor, and do not act at GABA binding site.