The effect of diabetes on rat hepatic ornithine decarboxylase (ODC) activity was studied in male rats 4 h to 8 days after the ip or iv administration of streptozotocin. Hepatic ODC activity increased 4-fold above control on the fourth day of diabetes. Increased ODC activity was observed with a dose of streptozotocin (70 mg/kg iv) which increased plasma ketones and glucagon and reduced plasma insulin. No change was seen with doses causing only mild hyperglycemia without change in plasma ketones, glucagon, or insulin. Insulin therapy prevented the increase in hepatic ODC activity in diabetic rats. Adrenalectomy or hypophysectomy also prevented the diabetes-associated increase of ODC activity. The studies suggest that insulin deficiency may result in increased hepatic polyamine synthesis.
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