ABSTRACT
Neurons and glia in the central nervous system can express the key enzymes for the synthesis of neurosteroids .Once the concentration of neurosteroids is high enough , they will exert paracrine effects .Synthesis of neurosteroids declines with age in brain .So does it under stressful circumstances .Recent research reports indicate that the decrease of neurosteroids is associated with the neuronal dysfunction and degeneration in the brain .This paper reviews recent research on the most studied neurosteroids ( for example , dehydroepiandrosterone , pregnenolone and their sulphate esters, progesterone and allopregnanolone ) in affecting neuronal survival , neurite outgrowth and neurogenesis , and the potential roles of these neurosteroids in the treatment of neurodegenerative disease as well .