Pathophysiological features in the brains of female Spontaneously Diabetic Torii (SDT) fatty rats

Diabetes mellitus (DM) and obesity are associated with neurodegenerative diseases such as Alzheimer's disease and psychiatric disorders such as major depression. In this study, we investigated pathophysiological changes in the brains of female Spontaneously Diabetic Torii (SDT) fatty rats with diabetes and obesity. Brains of Sprague-Dawley (SD), SDT and SDT fatty rats were collected at 58 weeks of age. The parietal cortical thickness was measured and the number of pyramidal cells in the hippocampal cornu ammonis 1 and 3 (CA1 and CA3) and the number of granule cells in the dentate gyrus (DG) regions were counted. The area of glial fibrillary acidic protein (GFAP) positivity in CA1, CA3 and DG regions were measured. The parietal cortical thickness and the number of cells in CA3 and DG regions of SDT and SDT fatty rats did not show obvious changes. On the other hand, in the CA1 region, the number of cells in SDT rats and SDT fatty rats was significantly lower than that in SD rats, and that in SDT fatty rats was significantly lower than that in SDT rats. The GFAP-positive area in SDT fatty rats was significantly reduced compared to that in SD rats only in the DG region. Preliminarily result showed that the expression of S100a9, an inflammation-related gene, was increased in the brains of SDT fatty rats. These results suggest that female SDT fatty rat may exhibit central nervous system diseases due to obesity and DM.