Corticosteroid synthesis in the central nervous system

The possibility that adrenocorticosteroids might be synthesized in the central nervous system was assessed by RT-PCR using primers for the CYP11B1 gene which codes for 11 beta-hydroxylase, the enzyme responsible for corticosterone and cortisol formation in the zona fasciculata, incubation of minces of several areas of the brain with 3H-DOC and measuring steroid metabolites, and determining the effect of the intracerebroventricular infusion of the 11 beta-hydroxylase mechanism-based inhibitor 19-ethynyldeoxycorticosterone upon the salt-induced increase in blood pressure in SS/jr rats. Significant, though small relative to the adrenal, amounts of mRNA for 11 beta-hydroxylase was found in the aorta, cerebrum, cerebellum, hippocampus, hypothalamus and amygdala, but not in the heart. Brain minces converted 3H-DOC to corticosterone and 11-dehydrocorticosterone to a greater degree than to 18-OH-DOC. The effect of 19-ethynyldeoxycorticosterone was dose dependent, with the lower doses preventing salt-induced hypertension and the higher doses having no effect or increasing the blood pressure.