Effects of Streptozotocin-Induced Type 1 Diabetes on Cell Proliferation and Neuronal Differentiation in the Dentate Gyrus; Correlation with Memory Impairment

초록

We examined the effects of steptozotocin (STZ)-induced type 1 diabetes on cell proliferation andneuroblasts in the subgranular zone of the hippocampal dentate gyrus (SZDG) of male Wistar rats. Change in memoryfunction was also investigated using the passive avoidance test. In the SZDG, Ki67 (a marker for cell proliferation)positive nuclei were significantly decreased at 2 and 3 weeks and slightly decreased at 4 weeks after STZ treatment. Doublecortin (DCX, a marker for neuronal differentiation)-immunoreactive (+) neuroblasts with tertiary dendrites weresignificantly decreased in the STZ-treated group compared to those in the vehicle-treated group. However, DCX+ neuroblastswithout tertiary dendrites were abundant at 4 weeks after STZ treatment. In addition, retention latency time inSTZ-treated group was similar to that of vehicle-treated group at 2 and 3 weeks after STZ treatment. However, theretention latency time was significantly decreased at 4 weeks after STZ treatment. These results suggest that STZ significantlyreduced cell proliferation and neuroblasts at 2~3 weeks after STZ treatment, but not at 4 weeks after STZtreatment although memory impairment was detected at 4 weeks after STZ treatment. The gradual reduction of DCX+neuroblasts with tertiary dendrites may be associated with the impairment of hippocampus-related memory function.

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