Uptake and Distribution of Exogenous Testosterone-1,2-³H in Neural and Genital Tissues of the Castrate Guinea Pig¹

Abstract

The amount of radioactive material recoverable from plasma, liver, hypothalamus, cerebellum, pituitary, prostate and seminal vesicle was studied in 15 castrated guinea pigs killed ¼, 1,4, 16 and 2 t hr following injection of 43 μc testosterone-1,2-3H. The peak of radioactivity in plasma was at 1 hr for ether extracts and 4 hr for butanol extracts. In the liver, both extracts peaked at 1 hr. At all times more butanolsoluble radioactivity was found in liver than in plasma. In all other organs butanol extracts were lower than plasma values. These values may be underestimated since butanol extracts may not be completely soluble in scintillation fluid. Thinlayer chromatography separated ether extracts into predominantly 2 zones: Zone A radioactivity with mobility of testosterone, and Zone B with mobility of androstenedione. In 7 animate sacrificed 1 hr following injection, the concentration of Zone A radioactivity was significantly higher than plasma in hypothalamus, cerebellum and pituitary, not significantly different in prostate or seminal vesicle, and significantly lower than plasma in liver. Relationships were different for Zone B radioactivity. Concentrations of this labeled material were highest for prostate and seminal vesicle. Hypothalamus, cerebellum and pituitary, while containing significantly higher concentrations than plasma, were significantly lower than genital tract tissues. Liver and plasma did not differ significantly. Total body perfusion with saline at sacrifice did not alter the relationships between organs for Zone A and Zone B radioactivity. Recrystallization to constant specific activity and paper chromatography in systems designed to separate metabolites showed that Zone A radioactivity of hypothalamus was predominantly in the form of “free” testosterone. Zone B radioactivity from prostate and seminal vesicle contained appreciable amounts of both andro3tenedione and etiocholanolone. (Endocrinology80: 490, 1967)