Changes of superoxide dismutase gene expression and activity in the brain of streptozotocin-induced diabetic rats

In an attempt to discover the changes of superoxide dismutase (SOD) in the brain of diabetic state, we investigated the level of SOD in streptozotocin -induced diabetic rats (STZ-diabetic rats) using enzyme activity assay, Nor thern blotting analysis of mRNA levels and Western blotting of enzyme amoun t. Five discrete brain regions, cerebrocortex, hypothalamus, hippocampus, t he remaining non-cortex cerebrum (NCC area) and cerebellum, were examined i n STZ-diabetic rats to compare with age-matched normal rats. Higher levels of Mn-SOD including the activity, mRNA expression and immunoblot of enzyme were found in all areas of the brain from STZ-diabetic rats as compared wit h that in Wistar rats. Except in the cerebellum, similar changes of Cu,Zn-S OD were found in the brain of STZ-diabetic rats. These results indicate an increase of SOD both gene expression and activity in the brain of STZ-diabe tic rats. This alteration of SOD may be one of the important factors for th e vulnerability of the brain to oxygen free radicals or may be related to t he pathophysiology of diabetes. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.