Abstract
A fluorometric method for determination of the 3β-hydroxysteroid dehydrogenase system in microgram samples of tissue, based on nicotinamide adenine dinucleotide reduction by pregnenolone, was developed and applied to the quantitative histologic distribution of the enzyme in the adrenal gland of the rat. Single subcutaneous injections of adrenocorticotropin in saline solution (25 mg/kg) and daily injections for 6 days of the same dose in gel resulted in no demonstrable influence on either the activity or distribution of the enzyme. The distribution observed was relatively uniform throughout the cortex, although a tendency to greater activity in the glomerulosa was found in some cases, and no appreciable activity was seen in the medulla. The data supported those in the literature, indicating that this enzyme is not rate limiting in the biosynthesis of corticosterone in the adrenal following stimulation by adrenocorticotropin.