Preventive and Therapeutic Effects of Nicotinamide and 3-Aminobenzamide in Hyperglycemic OLETF rats

We examined the preventive and therapeutic effects of nicotinamide and 3-aminobenzamide on diabetes in OLETF rats. Fifteen young (7-week old pre-diabetic) and twenty-eight old (36-75 week old diabetic) OLETF rats were each randomly divided into three groups, a nicotinamide group (0.05 g/kg body wt. day, intraperitoneally), a 3-aminobenzamide group (0.05 g/kg body wt · day, intraperitoneally), and a saline injected group (2 ml/kg body wt). After 90 days, we evaluated the development of diabetes on the basis of the results of an OGTT. Nicotinamide-injected young OLETF rats were prevented from developing diabetes, but all of the rats in the saline-injected group developed diabetes. Histopathologically, severe fibrosis and hypertrophy of the pancreatic islets were observed in the saline injected group but such findings in the nicotinamide-injected group were only slight. Moreover, in the old nicotinamide-injected OLETF rats the OGTT plasma glucose levels decreased and foci of islet hyperplasia consisting of newly formed cells were observed. In the 3 aminobenzamide injected OLETF rats, on the other hand, no clear preventive or therapeutic effects wrere observed and some oncogenic effects were suggested.