EFFECT OF CARBON TETRACHLORIDE ON INDUCTION OF LIVER ENZYMES BY ACUTE STRESS OR CORTICOSTERONE

The effects of single and repeated oral doses of carbon tetrachloride on the corticosterone-inducible liver enzymes, tyrosine-α-ketoglutarate transaminase (TKT), alkaline phosphatase (AP), and tryptophan pyrrolase (TP) were studied in rats. Corollary indices of liver injury that were measured included plasma alanine-α-ketoglutarate transaminase (AKT), plasma alkaline phosphatase, and liver glucose-6-phosphatase activities. Single doses of 0.25 ml/kg or greater of CCl4 increased liver TKT and AP activities but not TP activity. These effects occurred after an initial transient rise in plasma corticosterone. Liver TKT elevation, but not AP elevation, was prevented by adrenalectomy prior to CCl4. Experiments on rats subjected to simultaneous acute cold stress and CCl4 indicated that, during the acute phase of CCl4 hepatotoxicity, their livers had reduced capacity for induction of TKT and TP by endogenous corticosterone. However, chronically injured livers of rats given repeated doses of CCl4 were fully responsive to the TKT- and TP-inducing effects of exogenous corticosterone or acute cold stress. © 1969.