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: 17α-androstenediol, dehydroepiandrosterone, 5-androstenetriol (AET), 4-androstenedione (AND), testosterone, estradiol, fluasterone, 16α-bromoepiandrosterone, 16α-fluoro-androst-5-en-17α-ol (α-fluorohydrin, AFH), and 16α-fluoro-androst-5-en-17β-ol (β-fluorohydrin). Steroids were administered 24 or 48 hr before, or 1 hr after, whole-body γ-irradiation. Two days after irradiation at 3 Gy, blood elements were counted. In addition, after irradiation at 9–12.5 Gy, survival was recorded for 30 days. The results showed radioprotective efficacy was specific for 5-AED. One other steroid, AFH, demonstrated appreciable survival effects but was less efficacious than 5-AED. AND and AET produced slight enhancement of survival in some experiments. This is the first demonstration that the prophylactic window for survival enhancement by 1 subcutaneous (sc) injection of 5-AED is as long as 48 hr in mice. Moreover, the res...