Thirty years ago, the group of Baulieu and colleagues discovered that certain steroid hormones were present in higher amounts in the brain than in the plasma, and also found that suppression of circulating steroids by adrenalectomy and castration did not affect the concentration of pregnenolone, dehydroepiandrosterone and their sulfate esters in the rat brain. These seminal observations led to the concept that the brain, in very much the same way as the adrenal cortex, testis, ovary and placenta, was capable of synthesizing steroids. These brain born steroids, called neurosteroids, have been found to exert a vast array of biological activities. A number of steroidogenic enzymes have now been identified in the central nervous system by immunohistochemistry and in situ hybridization, and the neuronal and hormonal mechanisms regulating the biosynthesis of neurosteroids have been partially elucidated. The aim of this Research Topic is to celebrate three decades of research on neurosteroids by gathering a bouquet of review papers and original articles from leading scientists in the flourishing field of neurosteroids.
Picture: neurons expressing the steroidogenic enzyme 3β-hydroxysteroid dehydrogenase in the hypothalamus.