Radiation Protection by an Auxin Analogue, β-2,4,5- Trichlorophenoxyethanol, in C57BL/6J Mice exposed to Cobalt-60 Gamma Radiation

Abstract

OUR previous studies^1,2 have demonstrated that certain analogues of plant growth regulators kill free cells of the Ehrlich ascites carcinoma, both in vitro and in vivo. The specificity of the chemical structure of the auxin analogues for this cytocidal action suggests the possibility that the neoplastic transformation of an initially normal mammalian cell consists of its reversion to the primitive type of growth-control that is characteristic of a plant tumour cell. If this is indeed the case, it might be possible for auxin analogues to influence the rate and/or magnitude of responses of animals to ionizing radiation. Accordingly, we designed experiments to test the ability of such compounds to delay or prevent the death of mice subjected to normally lethal doses of γ-radiation from a cobalt-60 source. These experiments have shown that a 150-mg/kg dose of β-2,4,5-trichlorophenoxyethanol (2,4,5-TOH), an analogue of the selective herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), administered shortly before irradiation, affords a high degree of protection to C57BL/6J mice.