title: Molecular specificity of 5-androstenediol as a systemic radioprotectant in mice.
abstract: 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. 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 (s.c.) injection of 5-AED is as long as 48 hr in mice. Moreover, the results indicate that 1 s.c. injection of 5-AED 1 hr after irradiation is much less effective than 1 injection 24-48 hr before irradiation. Comparing the molecular features of steroids with radioprotective efficacy leads to the following conclusions: 1) these effects are due to interaction with specific receptors, since s.c. injection of extremely similar molecules with the same physicochemical properties as 5-AED were not radioprotective; 2) the 17-hydroxyl group is essential; 3) this group must be in the beta configuration in the absence of nearby side groups; 4) a halogen atom at 16 changes the 17-hydroxyl specificity to alpha; 5) the 3beta-hydroxyl group is not essential; 6) addition of a 7beta-hydroxyl group is deleterious; and 7) the effects are not due to activation of sex steroid receptors.
authors.affiliation: Radiation Casualty Management Team, Armed Forces Radiobiology Research Institute, 8901 Wisconsin Ave., Bethesda, MD 20889-5603, USA. whitnall@afrri.usuhs.mil
authors.forename: Mark H
authors.initials: MH
authors.lastname: Whitnall
authors.forename: Vilmar
authors.initials: V
authors.lastname: Villa
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Seed
authors.forename: James
authors.initials: J
authors.lastname: Benjack
authors.forename: Venita
authors.initials: V
authors.lastname: Miner
authors.forename: Marvin L
authors.initials: ML
authors.lastname: Lewbart
authors.forename: Charles A
authors.initials: CA
authors.lastname: Dowding
authors.forename: William E
authors.initials: WE
authors.lastname: Jackson
mesh_terms: D015114:Androstenediol / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000097:blood / Q000494:pharmacology*; D000818:Animals; D005260:Female; D005720:Gamma Rays / Q000009:adverse effects; D007958:Leukocyte Count; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D009504:Neutrophils / Q000187:drug effects / Q000528:radiation effects; D011837:Radiation-Protective Agents / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D011837:Radiation-Protective Agents; D015114:Androstenediol