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 CA 1 and dentate gyrus (DG), the total number of neurons and the total number of Spinophilin/NeurabinII-positive boutons in CA 1 and DG of streptozotocin-treated rat model. Fifty SpragueDawley 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 CA 1 volume (by 51.5%) and degeneration in synaptic structures in CA 1 sr (by 30.2%). While there were no significant changes in total DG volume, total neuron number in CA 1 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 CA 1 and DG of STZ-induced diabetic rats.

Steady‐state activation and modulation of the synaptic‐type α 1 β 2 γ 2L GABA A receptor by combinations of physiological and clinical ligands

“…The reported total cellular frequency of sIPSCs in various preparations ranges from ~1 to >10 Hz (Hajos and Mody ; Browne et al ; Chakrabarti et al ). With 10–1000 synapses per cell (Ichikawa et al ; Cullen et al ; Zhao et al ), the estimated frequency of sIPSCs per synapse thus varies between 0.001 and 1 Hz. Accordingly, the relative integrated charge transfer may range from 0.996:0.004 (at 0.001 Hz frequency per synapse) to 0.21:0.79 (at 1 Hz) for the ratio of tonic to phasic activity in the presence of ambient GABA and physiological taurine, 3 α 5 α P, and PS.…”

Neurobehavioral effects of long‐term maternal fructose intake in rat offspring

“…In other words, fructose exposure during gestation and lactation seems to have potential differential effects on neuronal survival and integrity of male and female offspring. It has been previously suggested that reduced synapse density and function often occur prior to neuronal death (Lepeta et al, 2016; Zhao et al, 2016). The decline in synaptic density is associated to the weakness of synaptic plasticity and function, and subsequently leads to cognitive deficit (Coleman et al, 2004).…”

Total Number Is Important: Using the Disector Method in Design-Based Stereology to Understand the Structure of the Rodent Brain

“…As mentioned previously, estimation of the total number of synapses with the disector method was rapidly adopted (Geinisman et al, 1992 , 1996 ). Numerous studies have used disector estimates of total synapse number to investigate changes resulting from a number of phenomena including protein undernutrition (Lukoyanov and Andrade, 2000 ), hypothyroidism (Madeira and Paula-Barbosa, 1993 ), aging (Poe et al, 2001 ), epilepsy (Thind et al, 2010 ; Yamawaki et al, 2015 ), diabetes (Zhao et al, 2016 ) and in some cases the reversibility of synapse change (Lukoyanov and Andrade, 2000 ; Yamawaki et al, 2015 ). Studies have also indicated that an increase in the number of synapses occurs with a change in behavior (Klintsova et al, 1997 ; Hajszan et al, 2009 ; Dalzell et al, 2011 ; Jasinska et al, 2016 ).…”

“…Faced with trying to understand the rodent brain, many neuroscientists consider that the total number of neurons/synapses is important and that reliable estimates of such values are an essential requirement of quantitative neuroscience. Numerous studies have used design-based stereology to enable a better understanding of the correlation of structure with function (Hédou et al, 2002 ; Schmitz and Hof, 2005 ; Zhao et al, 2016 ). The rapidly growing area of connectomics, previously known as neuroanatomical connections, is focused on the production of a map of connections within a specific brain region at a cellular or subcellular level (Mikula, 2016 ; Swanson and Lichtman, 2016 ).…”