[Effect of the antibiotic D-cycloserine and its dimer on the activity of tyrosine aminotransferase in liver tissue of intact, adrenalectomized and hypophysectomized rats].

In a period of lowest day activity of tyrosine aminotransferase, within 6-8 days after bilatheral adrenalectomy, the enzyme activity was decreased by about 20% as compared with an adequate control. At the same time, within a day and seven days after hypophisectomy, in rat liver tissue the enzyme activity was increased, approximately two-fold as compared with the normal state. Within four hrs after intraperitoneal administration into intact fasting rats at a dose of 2-2.5 g per 1 kg of body weight D-cycloserine and its dimer caused an induction of tyrosine aminotransferase by 75% and 180%, respectively. Induction of the enzyme by D-cycloserine and its dimer was inhibited by actinomycin D; the phenomenon was not observed in adrenalectomized rats. Within a day after hypophisectomy D-cycloserine did not cause the induction of tyrosine aminotransferase in rat liver tissue; to the contrary, the dimer of D-cycloserine caused induction of the enzyme, comparable to the ACTH effect, in liver tissue of hypophisectomized rats.