Inhibition by Radiation of the Development of Drug-Detoxification Enzymes

Abstract

A study was conducted to ascertain the influence of X-irradiation on the synthesis of detoxification enzymes. In the young male rat some of the detoxification enzymes located in the microsomal fraction of the liver exhibit two distinct phases of development. One phase occurs from the time of birth to about 21 days of age, and the second phase occurs from 21 to about 45 days of age. When weanling male rats were exposed to 100 R, 200 R, or 400 R of X-irradiation, a dose-dependent, reversible inhibition of the second phase of enzyme development occurred. This effect rendered the animals more susceptible to drugs that are detoxified by microsomal enzymes. Partial-body shielding experiments revealed that shielding the liver and testes areas did not prevent the inhibition of enzyme development. The inhibition occurred when only the head was irradiated, indicating that it is due to an abscopal effect. The nature of this indirect effect of radiation was not elucidated, but it seems possible that it involves an ab...