Over the past decade, it has become clear that the brain, like the gonad, adrenal and placenta, is a steroid genic organ. Neurosteroids are synthetized in the central and the peripheral nervous system, in glial cells, and also in neurons, from cholesterol or steroidal precursors imported from peripheral sources. However, unlike classic steroid genic tissues, the synthesis of steroids in the nervous system requires the coordinate expression and regulation of the genes encoding the steroid genic enzymes in several different cell types (neurons and glia) at different locations in the nervous system, and at distances from the cell bodies. The steroids synthesized by the brain and nervous system, given the name neurosteroids Progesterone itself is also a neurosteroid, and a progesterone receptor has been detected in peripheral and central glial cells. At different sites in the brain, neurosteroid concentrations vary according to environmental and behavioural circumstances, such as stress, sex recognition, or aggressiveness. Have a wide variety of diverse functions. In general, they mediate their actions, not through classic steroid hormone nuclear receptors, but through other mechanisms such as through ion gated neurotransmitter receptors, or through direct or indirect modulation of other neurotransmitter receptors. Briefly summarized the biochemistry of the enzymes involved in the biosynthesis of neurosteroids. This article presents a review on some reporteddeals with the synthesis and biosynthesis of neurosteroids and it may be important to study the effects of abnormal neurosteroid concentration metabolism in view of the possible treatment of functional and trophic disturbances of the nervous system.
