Abnormalities in the brain of streptozotocin-induced type 1 diabetic rats revealed by diffusion tensor imaging

Diabetes mellitus affects the brain. Both type 1 and type 2 diabetic patients are associated with white matter (WM) damage observable to diffusion tensor imaging (DTI). The underlying histopathological mechanisms, however, are poorly understood. The objectives of this study are 1) to determine whether streptozotocin (STZ)-induced type 1 diabetes is associated with WM damage observable to DTI; and 2) to understand the pathophysiological aspects underlying STZ-induced brain injuries. Male Sprague-Dawley rats received a single intraperitoneal injection of STZ (62 mg/kg). DTI was used to assess brain abnormalities at 4 weeks after induction, combined with histological assessments and ultrastructural analysis. Compared to controls, the STZ-induced rats showed significantly reduced fractional anisotropy (FA) in the motor/somatosensory cortex and striatum. Histologically, the cortex and striatum of the diabetic animals are characterized by demyelination and axonal degradation. In conclusion, STZ-induced diabetes is associated with striatal/cortical injuries observable to DTI. The DTI abnormalities are likely manifestations of demyelination and axonal degradation in the affected brain regions, and can potentially be used as surrogates for evaluating diabetic brain injuries.