||Health Effects Research Lab., Cincinnati, OH. ;Environmental Health Research and Testing, Inc., Cincinnati, OH. ;National Inst. for Occupational Safety and Health, Cincinnati, OH.
Chloroform stimulation of rat hepatic ornithine decarboxylase (ODC) is most dramatic at 18 h following a single injection. Repeated dosing, 1 dose/d for up to 7 d, results in a daily decline in the ability of the liver enzyme to respond 18 h after the final injection. This decline was probably due to an increased synthesis and accumulation of the ODC-antizyme (AZ) protein. ODC-AZ was determined by measuring the inhibition of isolated ODC activity. Rats were injected daily for 1, 3, or 7 d with 3.0 mmol/kg chloroform. Chloroform induced ODC-AZ activity in males at 3 and 7 d (26% and 37% inhibition of the ODC activity in the incubation medium, respectively). While females exhibited a similar decline in ODC activity after repeated doses, ODC-AZ was not induced. Thus, it would appear that daily exposure of rats to chloroform results in a refractoriness of its induction of ODC activity accompanied by an induction of the ODC-AZ in males. However, in females these two responses were not directly related. (Copyright (c) 1988 Hemisphere Publishing Corp.)