Memory function and total pyramidal neuron number of hippocampus in streptozotocin-induced diabetic rats

Introduction: Cognitive impairments caused by diabetes mellitus are well documented by previous studies. The studies about neuronal deficits and cognitive impairments in animal models of diabetes mellitus do not simultaneously indicate the total neuron number in the brain subfields and cognitive test performance. In this study, we simultaneously demonstrated total pyramidal neuron number of hippocampus and water maze test performance in streptozotocin-induced diabetic rats.Material and method: Male Wistarrats were randomly divided into three groups: Control, Sham and Diabetic. Diabetes was induced by intraperitoneal injection of60 mg/kg streptozotocin and blood glucose levels were tested in all rats three and ten days after injection. The rats with blood glucose levels above 300 mg/dl were declared diabetic. Six weeks after induction of diabetes, a version of Morris Water Maze test was applied to evaluate cognitive impairments. All rats were sacrificed for stereological procedures after the test, and total pyramidal neuron number of hippocampus was estimated by using stereological methods.Results: Streptozotocin induced diabetic rats had a significantly lower total pyramidal neuron number in both CA1 and CA3-2 regions of the hippocampus than that of normal control and sham group rats. Additionally, learning and memory impairments in the Morris Water Maze test accompanied by reduced hippocampal pyramidal neuron number in diabetic rats.Conclusion: Results of our present study revealed that reduced hippocampal pyramidal neuron number, which is triggered by streptozotocin-induced diabetes, leads to learning and memory impairments in rats. © 2014 Ege University Press. All rights reserved