Abstract: The distribution of tau protein in the brain was studied in the groups of the healthy, controled mice, diabetic mice, and diabetic mice treated with APP17mer peptide, in order to examine the effect of APP17mer peptide on phosphorylation of tau protein and its potential to treat neurodegeneration. The diabetic mouse model was created with STZ. APP17mer peptide was used for treatment. Four weeks later, cryostat sections of the brain was prepared for immunohistochemical study with Tau 1 monoclonal antibody and after dephosphorylation with phosphatase PP-2B. On staining with Tau-1 the brain of the healthy mice and the diabetic mice treated with APP17mer peptide showed numerous immunopositive cells in the granular layer of the cortex, and in the hippocampus. The staining was dark (P<0.05). Only after dephosphorylation with PP-2B did the number and staining of immunopositive neurons in diabetic mice reach the level in healthy mice. The results demonstrate that tau protein is phosphorylated at Ser202/Ser205 in diabetic mice. APP17mer peptide can prevent the phosphorylation of tau protein at these sites.

Key words: diabetic encephalopathy, tau protein, APP17mer peptide, immunohistochemistryD