SummaryHistopathological examinations were carried out on femaie DBA/2N and CD·l mice which were autopsied 4 and 12 weeks after six daily intraperitoneal injections of streptozotocin (SZ). Histopathological changes related to SZ treatment were found in the pancreas, liver and kidneys. Little difference was observed between the two strains in the histological changes of the pancreas (a decrease in size of the islets, and degranulation and a decrease in the number of B cells) and liver (hypertrophy of hepatocytes and cytoplasmic invagination into hepatocyte nuclei). With regard to the changes in the kidneys, DBA/2N mice showed characteristic inclusions positive to periodic acid-Schiff reagent in the distal tubule epithelial cells, while CD-l mice showed remarkable luminal dilatation and epithelial cell deformation of distal tubules. SZ-induced diabetes had no innuence on the development of spontaneous cardiovascular lesions in DBA/2N mice under the present experimental conditions.
Keywords: Mice; Streptozotocin; Diabetes mellitus, experimental; Pancreatic diseases; Liver diseases; Kidney diseasesStreptozotocin (SZ), which was originally developed as an antibiotic and antitumour agent, is now widely used to induce insulin-dependent diabetes mellitus in rodents because of its toxic action on islet B cells (Like et al., 1978). However, it is also known that SZ has acute toxic effects on many organs in some animal species (Levine et al., 1980) and leads to delayed-type renal toxicity in rats (Rakieten et al., 1968;Okawa & Doi, 1983). This suggests that full attention should be paid to histopathological changes in other organs as well as the pancreas when SZ-treated animals are used for studies on diabetes. There are only a few reports, however, on the systemic histopathology of SZ-induced diabetic animals (Arison et al., 1967) generally said that diabetes accelerates the progression of existing cardiovascular lesions in humans.In this paper we report the histopathology of the main organs in SZ-induced diabetic DBA/2N and CD-l mice and the influence of hyperglycaemia on the development of spontaneous cardiovascular lesions in DBAl2N mice (Doi et al., 1985;Maeda, Doi & Mitsuoka, 1986) up to 12 weeks after SZ treatment.Materials and methods 43 female DBA/2NCrj (DBA/2N) mice weighing 10-14 g each and 20 female CRJ:CD-l (CD-I) mice weighing 17-21 g each were obtained from Charles River Japan Inc., Atsugi, Kanagawa, at 4 weeks of age. The mice were housed in an animal room at a temperature of 23 ± 2°C with a relative humidity of 55 ± 5% and were fed CRF-l (Charles River Japan Inc.) and water ad libitum.At 5 weeks of age, 23 DBA/2N and 10 CD-l mice received SZ at 50 mg/kg of bodyweight per day for six consecutive days. SZ (Sigma Chemical Company, St. Louis, MO, USA) was dissolved in citrate buffer (pH 4·5) immediately before daily intraperitoneal injection. The remaining mice of each strain received citrate buffer alone in the same way and served as controls. Bodyweight and food and water intake for 24 h were measured weekly...