Corticosteroid production by fetal rat hippocampal neurons

11 beta -hydroxylase and aldosterone synthase catalyse the final stages of corticosterone and aldosterone synthesis respectively. previously, we estab lished that they are expressed in the rat brain, particularly the cerebellu m and the hippocampus. Primary cultures of fetal rat neurons were studied. RT-PCR and immunohistochemistry established that neurons express 11 beta -h ydroxylase and aldosterone synthase mRNAs and protein. After incubating the cells with 10 muM DOC for 24 hours, medium was analysed for aldosterone an d corticosterone. Median % conversion of DOC to corticosterone was 7.6% com pared to 0.4% in controls. Median % conversion of DOC to aldosterone was 6. 2% compared to 0.06% in controls. Corticosteroids mediate a number of funct ions of mammalian brain, including blood pressure homeostasis, salt appetit e and neuronal excitability. Local production of these steroids could have significant effects on these processes.