Changes in Neurons and Synapses in Hippocampus of Streptozotocin-Induced Type 1 Diabetes Rats: A Stereological Investigation

Abstract

Previous studies have indicated that diabetes could cause hippocampus atrophy, neuron loss, and synaptic plasticity impairment. However, biological conclusions based on density were difficult to interpret because the changes in density could be due to an alteration of total quantity and/or an alteration in the reference volume. In the present study, we used unbiased stereological methods to investigate the effects of type 1 diabetes on the total volume of CA1 and dentate gyrus (DG), the total number of neurons and the total number of Spinophilin/NeurabinII-positive boutons in CA1 and DG of streptozotocin-treated rat model. Fifty Sprague–Dawley rats were randomly divided into sodium citrate buffer-treated group (control group) and streptozotocin (STZ)-treated group (diabetes group), in which type 1 diabetes was induced by streptozotocin injection. Learning and memory were measured using the Morris water maze test. Our results indicated that diabetes induced deficit in learning/memory, decrease in total CA1 volume (by 51.5%) and degeneration in synaptic structures in CA1sr (by 30.2%). While there were no significant changes in total DG volume, total neuron number in CA1 and DG, total Spinophilin/NeurabinII-positive bouton number in DG. The present study provided the first evidence of changes in the total volume, the total neuron number and the total Spinophilin/NeurabinII-positive bouton number in CA1 and DG of STZ-induced diabetic rats. Anat Rec, 299:1174–1183, 2016. © 2016 Wiley Periodicals, Inc.