Induction of ornithine decarboxylase activity by 4,4'-methylene bis(2-chloroaniline) in the rat

The effects of the curative extender 4,4'-methylene bis (2-chloraniline) (MOCA), an established experimental carcinogen that exhibits activity in rat liver, on hepatic ornithine decarboxylase (ODC) activity was investigated. Male Sprague-Dawley rats were injected i.p. with 75 mg/kg MOCA and killed 6, 12, 18, 24, 42 and 48 h later. Stimulation with MOCA of liver cytosolic ODC was first evident at 6 h, peaked at 12 h and returned to control levels by 42 h. The liver enzyme was refractory to stimulation by a second treatment of MOCA within the dosing intervals examined. The magnitude of stimulation of the enzyme by this aromatic amine was dependent on dose and route of administration.