Distribution of estrone sulfatase in rat brain determined by in vitro autoradiography with 16α-[18F]fluoroestradiol-3,17β-disulfamate

16α-Fluoroestradiol-3,17β-disulfamate (FESDS) strongly inhibits estrone sulfatase (ES), an enzyme which is also present in the brain. The enzyme is probably involved in important regulatory functions of neurosteroids which may be disturbed in certain brain diseases. In the present study, [18F]FESDS was used to measure the amount of ES in various rat brain regions using quantitative in vitro autoradiography. The obtained values vary between 0.29 pmol (mg protein)–1 (pons) and 11.5 pmol (mg protein)–1 (striatum). They are positively correlated with the enzyme activity measured in homogenates of the corresponding regions. Because this radiotracer binds also to carbonic anhydrase in the brain it is only of limited use for in vivo imaging studies.