CYTOCHEMICAL LOCALIZATION OF GLUCOSE 6-PHOSPHATASE ACTIVITY IN THE LIVER OF GROWING MICE AFTER PHENOBARBITAL TREATMENT

The proliferation of the smooth-surfaced endoplasmic reticulum (SER) and the cytochemical localization of glucose 6-phosphatase (G6Pase) activity after phenobarbital treatment were observed in postnatal mouse livers showing rapid proliferation of SER and in adult livers. Animals received one daily intraperitoneal injection of phenobarbital for 3 or 5 days in a dosage of 35mg per kg of body weight for the first 3 days after birth, 50mg per kg for 3 to 9 days after birth, and 50 or 100mg per kg for the adult.Administration of phenobarbital to growing animals did not change the histochemical distribution of G6Pase activity within the liver lobule in contrast with reduction observed in the centrolobular activity in adult animals after the same dose of phenobarbital. An extensive proliferation of SER was noticed in centrolobular hepatocytes from adult animals treated with 100mg per kg of phenobarbital, while no such proliferation occurred after treatment with 50mg per kg of phenobarbital. However, centrolobular hepatocytes of 5- to 10-day-old animals showed a marked proliferation of SER with 50mg per kg of phenobarbital. These observations suggest that there are some differences in the nature of the phenobarbital-induced proliferation of SER between hepatocytes during the postnatal period and fully differentiated hepatocytes of the adult.