Testosterone 5α‐Reductase in Rat Brain

Publisher Website
Google Scholar
Abstract
We describe a simple procedure for the microassay of testosterone 5α-reductase in homogenates of rat brain. This enzyme converts testosterone to dihydrotestosterone. We have used this assay to characterize the enzymatic activity and to map its distribution. The apparent Km is 4.1 × 10−6 M and the Vmax is 85.6 pmol/mg protein/h. The pH optimum is broad and extends from pH 6.0 to 8.0. For the brain regions surveyed, testosterone 5α-reductase activity varied over a 10-fold range. The highest activities were observed in homogenates of the midbrain and pons (37–39 pmol/mg protein/h). The lowest were seen in homogenates of the thalamus, caudate nucleus, frontal cortex, hippocampus, hypothalamus, olfactory tubercle, and preoptic area (3–7 pmol/mg protein/h).