Thein Vitroandin VivoUptake and Metabolism of Steroids in Human Adipose Tissue1

Abstract

The uptake and metabolism of various steroids in adipose tissue have been studied using both in vitro and in vivo techniques. The in vitro uptake of progesterone and testosterone (60%) was found to be much higher than the uptake of cortisol and estriol (13%). In vivo, the uptake of testosterone, androstenedione, estrone and estradiol by the total adipose mass was much greater in obese patients than in non obese individuals. Estrone and estradiol were found to be interconvertible following incubation with human adipose tissue slices. In vitro, progesterone was metabolized to a variety of compounds with 20α-dihydroprogesterone⁴ being the major metabolite. No conversion of cholesterol or cholesterol sulfate to pregnenolone or pregnenolone sulfate could be demonstrated in the brown adipose tissue of a newborn infant. In human adult subcutaneous adipose tissue, there was no in vitro conversion of progesterone to testosterone and no aromatization of androstenedione or testosterone labeled with ¹⁴C was detected. There was also no in vivo interconversion of estrone and estradiol in the mesenteric adipose tissue of the dog. In human subcutaneous adipose tissue, the in vivo interconversion of testosterone and androstenedione (ρ^TΔ: 12.2%;ρ^ΔT:0.95%) was demonstrated.