THE ASSAY OF SUBCUTANEOUSLY INJECTED ANDROGENS IN THE CASTRATED RAT

Abstract

ABSTRACT An assay procedure using the immature castrated albino rat is described using the weight of the seminal vesicles, ventral prostate, and levator ani as end-points in a ten day assay. The sensitivity was of the order of 0.6 mg of testosterone injected subcutaneously once daily in an aqueous suspending medium. The precision was adequate as judged by the λ values of 0.096 to 0.137 for the seminal vesicles, 0.128 to 0.162 for the ventral prostate, and 0.171 to 0.248 for the levator ani. Activity of testosterone was increased significantly by esterification, by introduction of the 17α-methyl group, and by reduction of the Δ4 double bond to the 5α form. Androgenic activity was decreased significantly by oxidation of the 17β-hydroxy group to the 17-keto group and introduction of methyl groups at the 2α- or 6α-positions.