The influence of partial hepatectomy on the biphasic response of gamma glutamyl transpeptidase to aflatoxin B1

We previously observed a biphasic response in rat hepatic gamma glutamyl transpeptidase (GGT) activity to aflatoxin B1 (AFB1) feeding 9]. We have extended this observation to examine the effect of partial hepatectomy (PH) on the activity and distribution of GGT at different stages of the feeding regime. In control-fed animals GGT levels were elevated 3-7 days after PH with increased activity in periportal hepatocytes. In animals fed a sub-carcinogenic dose of AFB1 (up to 4 weeks) the effect of PH on GGT activity was similar to that in control animals, but increased activity was mainly due to biliary hyperplasia. There was no obvious difference between animals returned to control diet after PH and those returned to toxic diet. In animals fed 4-15 weeks the percentage increase in GGT activity 1 week after PH correlated with length of time on AFB1 diet before operation, with an increase in number and size of altered foci. These results further support the idea that there is a preliminary toxic response in GGT activity followed by a secondary response more closely related to the carcinogenic process.