Neurosteroids are steroids synthesized within the central nervous system as well as in other steroidogenic organs/tissues. In contrary with the classical actions through intracellular receptors, extensive evidence has established that neurosteroids can exert rapid, potent actions at the cell membrane via allosteric interactions with the GABAA receptor. Pregnenolone is a naturally occurring neurosteroid directly metabolized from cholesterol and the precursor of virtually all neurosteroids.