Abstract
A new spontaneously diabetic strain of the Sprague-Dawley rat was established in 1997 and named the SDT (Spontaneously Diabetic Torii) rat. In this research, we investigated the characteristics of the disease condition in the SDT rats. The time of onset of glucosuria was different between male and female SDT rats; glucosuria appeared at approximately 20 weeks of age in male rats and at approximately 45 weeks of age in female rats. A cumulative incidence of diabetes of 100% was noted by 40 weeks of age in male rats, while it was only 33.3% even by 65 weeks of age in female rats. The survival rate up to 65 weeks of age was 92.9% in male rats and 97.4% in female rats. Glucose intolerance was observed in male rats from 16 weeks of age. The clinical characteristics of the male SDT rats were (1) hyperglycemia and hypoinsulinemia (from 25 weeks of age); (2) long-term survival without insulin treatment; (3) hypertriglyceridemia (by 35 weeks of age); however, no obesity was noted in any of the male rats. The histopathological characteristics of the male rats with diabetes mellitus (DM) were (1) fibrosis of the pancreatic islets (by 25 weeks of age); (2) cataract (by 40 weeks of age); (3) tractional retinal detachment with fibrous proliferation (by 70 weeks of age) and (4) massive hemorrhaging in the anterior chamber (by 77 weeks of age). These clinical and histopathological characteristics of the disease in SDT rats resemble those of human Type 2 diabetes with insulin hyposecretion. In conclusion, SDT rat is considered to be a potentially useful model for studies of diabetic retinopathy encountered in humans.
Highlights
Diabetes mellitus (DM) has become a global health problem; the incidence of the disease is graually increasing in all regions of the world. [1,2,3] The number of people sufferingPresent address: Japan Tobacco Inc., Toxicology Research Laboratories, Central Pharmaceutical Research Institute, 23Nakogi, Hatano, Kanagawa 257-0024, Japan.Present address: Japan Tobacco Inc., Central Pharmaceutical Research Institute, 1-1 Murasaki-cho, Takatuki, Osaka 569-1125, Japan.from DM is expected to rise to 2.21 billion by the year 2010. [4] Diabetes is not a disease of any single organ
Glucosuria, polyuria and polydipsia were observed in male Spontaneously Diabetic Torii (SDT) rats after 20 weeks of age and the nonfasting plasma levels of insulin, glucose and triglyceride began to change after 25 weeks
The SDT strain of rats was separated from outbred Crj:CD(SD) rats, and this strain was used as a reference to the SDT strain
Summary
Diabetes mellitus (DM) has become a global health problem; the incidence of the disease is graually increasing in all regions of the world. [1,2,3] The number of people sufferingPresent address: Japan Tobacco Inc., Toxicology Research Laboratories, Central Pharmaceutical Research Institute, 23Nakogi, Hatano, Kanagawa 257-0024, Japan.Present address: Japan Tobacco Inc., Central Pharmaceutical Research Institute, 1-1 Murasaki-cho, Takatuki, Osaka 569-1125, Japan.from DM is expected to rise to 2.21 billion by the year 2010. [4] Diabetes is not a disease of any single organ. Rats [14] are well known These models, in which the pattern of progression and symptoms closely mimic those of DM in humans, play a significant role in diabetes research, even though any single model may be inadequate for clarifying all the issues related to the disease. We established a new inbred strain, the Spontaneously Diabetic Torii (SDT) rats, which survive for a long time with hyperglycemia, even without insulin therapy and may be useful for the research of retinopathy. They exhibit tractional retinal detachment with fibrous proliferation of retinopathy similar to that occurring in human diabetes. We describe the pathophysiological characteristics of SDT rats
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