Molecular specificity of 5-androstenediol as a systemic radioprotectant in mice.

We compared in vivo radioprotective efficacy of 5-androstenediol (5-AED) to that of ten other steroids: 17alpha-androstenediol, dehydroepiandrosterone, 5-androstenetriol (AET), 4-androstenedione (AND), testosterone, estradiol, fluasterone, 16alpha-bromoepiandrosterone, 16alpha-fluoro-androst-5-en-17alpha-ol (alpha-fluorohydrin, AFH), and 16alpha-fluoro-androst-5-en-17beta-ol (beta-fluorohydrin). Steroids were administered 24 or 48 hr before, or 1 hr after, whole-body gamma-irradiation. Two days after irradiation at 3 Gy, blood elements were counted.