[The investigation of Syn and NPY expression in brain tissues of diabetic model rat induced by streptozotocin].

The synaptophysin (Syn) and neuropeptide Y (NPY) expressions in brain tissue of diabetic model rats were investigated. 20 adult Sprague-Dawley male rats were randomly divided into two groups. 10 rats were injected with streptozotocin to induce diabetes, which was identified by blood & urinary sugar level; and the others were injected with sodium citrate buffer as the control. After 4 weeks' diabetes appearance, the learning and memory ability of each rat in both group were tested by Y-Maze. Afterward freeze sections from the frontal cortex and hippocampus were made and stained with Nissl and Syn, NPY Immunohistochemistry staining. It was observed that diabetic rats showed more errors in Y-Maze test than those control rats. Both the number of neurons and the light densities of Syn and NPY immunostaining reaction in the frontal cortex and hippocampus of brain tissue sections significantly decreased in the diabetic model rats. It is suggested that the decrease in neuron number and Syn, NPY expression in frontal cortex and hippocampus may be one of the factors leading to diabetic dementia.