The Human and Rat Choroid Plexus Express Key Elements of the Neurosteroidogenesis Pathway

Neurosteroids are important regulators of numerous central nervous system (CNS) functions, playing essential roles in protecting the brain from insults such as neurodegeneration or ischemia. The choroid plexus (CP) epithelial cells establish an important physical interface between the peripheral blood and the cerebrospinal fluid (CSF), the Blood-CSF barrier (BCSFB), contributing to CNS homeostasis. There is evidence that the BCSFB is a target of sex steroid hormones, which regulate the expression of neuroprotective proteins. In contrast to other brain regions, little is known regarding the production of neurosteroids in the CP. Previously, a cDNA microarray analysis of the CP transcriptome showed the expression of several enzymes involved in steroidogenesis. We, therefore, investigated whether the key steroidogenic enzymes P450scc, P450aro, 17βHSD3, 17βHSD8, 5α-reductase 1, and 5α-reductase 2 are present in the rat and human CP. The present study demonstrates mRNA and protein expression of these enzymes in rat and human CP. Collectively the present data suggest that neurosteroids can be synthesised at the BCSFB and released into the CSF contributing to brain neuroprotection.