scholarly journals Comparative 2D and 3D Ultrastructural Analyses of Dendritic Spines from CA1 Pyramidal Neurons in the Mouse Hippocampus

2021 ◽  
Vol 22 (3) ◽  
pp. 1188
Author(s):  
Maria Nicol Colombo ◽  
Greta Maiellano ◽  
Sabrina Putignano ◽  
Lucrezia Scandella ◽  
Maura Francolini
Keyword(s):  
Pyramidal Neurons ◽  
Brain Connectivity ◽  
Three Dimensional ◽  
Excitatory Synapses ◽  
Spine Density ◽  
Functional Impairments ◽  
Small Complex ◽  
Hippocampal Ca1 ◽  
3D Em ◽  
2D And 3D

Three-dimensional (3D) reconstruction from electron microscopy (EM) datasets is a widely used tool that has improved our knowledge of synapse ultrastructure and organization in the brain. Rearrangements of synapse structure following maturation and in synaptic plasticity have been broadly described and, in many cases, the defective architecture of the synapse has been associated to functional impairments. It is therefore important, when studying brain connectivity, to map these rearrangements with the highest accuracy possible, considering the affordability of the different EM approaches to provide solid and reliable data about the structure of such a small complex. The aim of this work is to compare quantitative data from two dimensional (2D) and 3D EM of mouse hippocampal CA1 (apical dendrites), to define whether the results from the two approaches are consistent. We examined asymmetric excitatory synapses focusing on post synaptic density and dendritic spine area and volume as well as spine density, and we compared the results obtained with the two methods. The consistency between the 2D and 3D results questions the need—for many applications—of using volumetric datasets (costly and time consuming in terms of both acquisition and analysis), with respect to the more accessible measurements from 2D EM projections.

scholarly journals Activity-Induced Nr4a1 Regulates Spine Density and Distribution Pattern of Excitatory Synapses in Pyramidal Neurons

Neuron ◽  
2014 ◽  
Vol 83 (2) ◽  
pp. 431-443 ◽  
Author(s):  
Yelin Chen ◽  
Yuanyuan Wang ◽  
Ali Ertürk ◽  
Dara Kallop ◽  
Zhiyu Jiang ◽  
...  
Keyword(s):  
Distribution Pattern ◽  
Pyramidal Neurons ◽  
Excitatory Synapses ◽  
Spine Density

scholarly journals Mild Hypothermia Prevents Post-Traumatic Hyperactivity of Excitatory Synapses in Rat Hippocampal CA1 Pyramidal Neurons

2009 ◽  
Vol 56 (3/4) ◽  
pp. 49-59 ◽  
Author(s):  
SATOMI OOBA ◽  
HIROSHI HASUO ◽  
MINORU SHIGEMORI ◽  
SHIN YAMASHITA ◽  
TAKASHI AKASU
Keyword(s):  
Pyramidal Neurons ◽  
Mild Hypothermia ◽  
Excitatory Synapses ◽  
Ca1 Pyramidal Neurons ◽  
Hippocampal Ca1 ◽  
Post Traumatic

scholarly journals A connectomic study of a petascale fragment of human cerebral cortex

2021 ◽  
Author(s):  
Alexander Shapson-Coe ◽  
Michal Januszewski ◽  
Daniel R Berger ◽  
Art Pope ◽  
Yuelong Wu ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
High Speed ◽  
Pyramidal Neurons ◽  
Three Dimensional ◽  
Cell Types ◽  
Dimensional Structure ◽  
Inhibitory Synapses ◽  
Excitatory Synapses ◽  
Split And Merge ◽  
Surgical Sample

We acquired a rapidly preserved human surgical sample from the temporal lobe of the cerebral cortex. We stained a 1 mm3 volume with heavy metals, embedded it in resin, cut more than 5000 slices at ~30 nm and imaged these sections using a high-speed multibeam scanning electron microscope. We used computational methods to render the three-dimensional structure of 50,000 cells, hundreds of millions of neurites and 130 million synaptic connections. The 1.3 petabyte electron microscopy volume, the segmented cells, cell parts, blood vessels, myelin, inhibitory and excitatory synapses, and 100 manually proofread cells are available to peruse online. Despite the incompleteness of the automated segmentation caused by split and merge errors, many interesting features were evident. Glia outnumbered neurons 2:1 and oligodendrocytes were the most common cell type in the volume. The E:I balance of neurons was 69:31%, as was the ratio of excitatory versus inhibitory synapses in the volume. The E:I ratio of synapses was significantly higher on pyramidal neurons than inhibitory interneurons. We found that deep layer excitatory cell types can be classified into subsets based on structural and connectivity differences, that chandelier interneurons not only innervate excitatory neuron initial segments as previously described, but also each others initial segments, and that among the thousands of weak connections established on each neuron, there exist rarer highly powerful axonal inputs that establish multi-synaptic contacts (up to ~20 synapses) with target neurons. Our analysis indicates that these strong inputs are specific, and allow small numbers of axons to have an outsized role in the activity of some of their postsynaptic partners.

scholarly journals Five hours total sleep deprivation does not affect CA1 dendritic length or spine density

2021 ◽  
Author(s):  
Alvin T.S. Brodin ◽  
Sarolta Gabulya ◽  
Katrin Wellfelt ◽  
Tobias E. Karlsson
Keyword(s):  
Sleep Deprivation ◽  
Dendritic Spine ◽  
Pyramidal Neurons ◽  
Memory Function ◽  
Long Term Memory ◽  
Spine Density ◽  
Dendritic Length ◽  
Dendritic Spine Density ◽  
Hippocampal Ca1

AbstractSleep is essential for long term memory function. However the neuroanatomical consequences of sleep loss are disputed. Sleep deprivation has been reported to cause both decreases and increases of dendritic spine density. Here we use Thy1-GFP expressing transgenic mice to investigate the effects of acute sleep deprivation on the dendritic architecture of hippocampal CA1 pyramidal neurons. We found that five hours of sleep deprivation had no effect on either dendritic length or dendritic spine density. Our work suggests that no major neuroanatomical changes result from one episode of sleep deprivation.

scholarly journals Divergent Roles ofp75NTRand Trk Receptors in BDNF's Effects on Dendritic Spine Density and Morphology

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Christopher A. Chapleau ◽  
Lucas Pozzo-Miller
Keyword(s):  
Dendritic Spine ◽  
Pyramidal Neurons ◽  
Dendritic Morphology ◽  
Spine Density ◽  
Trk Receptors ◽  
Trk Receptor ◽  
Dendritic Spine Density ◽  
Trkb Receptors ◽  
Hippocampal Ca1 ◽  
Bdnf Signaling

Activation of TrkB receptors by brain-derived neurotrophic factor (BDNF) followed by MAPK/ERK signaling increases dendritic spine density and the proportion of mature spines in hippocampal CA1 pyramidal neurons. Considering the opposing actions ofp75NTRand Trk receptors in several BDNF actions on CNS neurons, we tested whether these receptors also have divergent actions on dendritic spine density and morphology. A function-blocking anti-p75NTRantibody (REX) did not affect spine density by itself but it prevented BDNF’s effect on spine density. Intriguingly, REX by itself increased the proportion of immature spines and prevented BDNF's effect on spine morphology. In contrast, the Trk receptor inhibitor k-252a increased spine density by itself, and prevented BDNF from further increasing spine density. However, most of the spines in k-252a-treated slices were of the immature type. These effects of k-252a on spine density and morphology required neuronal activity because they were prevented by TTX. These divergent BDNF actions on spine density and morphology are reminiscent of opposing functional signaling byp75NTRand Trk receptors and reveal an unexpected level of complexity in the consequences of BDNF signaling on dendritic morphology.

scholarly journals Kalirin-7 is a Key Player in the Formation of Excitatory Synapses in Hippocampal Neurons

2010 ◽  
Vol 10 ◽  
pp. 1655-1666 ◽  
Author(s):  
Xin-Ming Ma
Keyword(s):  
Hippocampal Neurons ◽  
Pyramidal Neurons ◽  
Synapse Formation ◽  
Pdz Domain ◽  
Long Term Potentiation ◽  
Binding Motif ◽  
Excitatory Synapses ◽  
Spine Density ◽  
Chronic Cocaine ◽  
And Function

Kalirin-7 (Kal7), a major isoform of Kalirin in the adult rodent hippocampus, is exclusively localized to the postsynaptic side of mature excitatory synapses in hippocampal neurons. Kal7 interacts with multiple PDZ domain—containing proteins through its unique PDZ binding motif. Overexpression of Kal7 increases spine density and spine size, whereas reduction of endogenous Kal7 expression by small hairpin RNA (shRNA) causes a decrease in synapse number and spine density in cultured hippocampal neurons. Hippocampal CA1 pyramidal neurons of Kal7 knockout (Kal7KO) mice show decreased spine density, spine length, synapse number, and postsynaptic density (PSD) size in their apical dendrites; are deficient in long-term potentiation (LTP); and exhibit decreased frequency of spontaneous excitatory postsynaptic current (sEPSC). Kal7 plays a key role in estrogen-mediated spine/synapse formation in hippocampal neurons. Kal7 is also an essential determinant of dendritic spine formation following chronic cocaine treatment. Kal7 plays a key role in excitatory synapse formation and function.

scholarly journals Restoring striatal WAVE-1 improves maze exploration performance of GluN1 knockdown mice

2018 ◽  
Author(s):  
Yuxiao Chen ◽  
Marija Milenkovic ◽  
Ali Salahpour ◽  
Scott H. Soderling ◽  
Amy J. Ramsey
Keyword(s):  
Rho Gtpases ◽  
Pyramidal Neurons ◽  
Medium Spiny Neuron ◽  
Long Term Memory ◽  
Spine Density ◽  
Cognitive Domains ◽  
Protein Levels ◽  
Y Maze ◽  
Hippocampal Ca1

AbstractNMDA receptors are important for cognition and are implicated in neuropsychiatric disorders. GluN1 knockdown (GluN1KD) mice have reduced NMDA receptor levels, striatal spine density deficits, and cognitive impairments. However, how NMDA depletion leads to these effects is unclear. Since Rho GTPases are known to regulate spine density and cognition, we examined the levels of RhoA, Rac1, and Cdc42 signaling proteins. Striatal Rac1-pathway components are reduced in GluN1KD mice, with Rac1 and WAVE-1 deficits at 6 and 12 weeks of age. Concurrently, medium spiny neuron (MSN) spine density deficits are present in mice at these ages. To determine whether WAVE-1 deficits were causal or compensatory in relation to these phenotypes, we intercrossed GluN1KD mice with WAVE-1 overexpressing (WAVE-Tg) mice to restore WAVE-1 levels. GluN1KD-WAVE-Tg hybrids showed rescue of striatal WAVE-1 protein levels and MSN spine density, as well as selective behavioral rescue in the Y-maze and 8-arm radial maze tests. GluN1KD-WAVE-Tg mice expressed normalized WAVE-1 protein levels in the hippocampus, yet spine density of hippocampal CA1 pyramidal neurons was not significantly altered. Our data suggest a nuanced role for WAVE-1 effects on cognition and a delineation of specific cognitive domains served by the striatum. Rescue of striatal WAVE-1 and MSN spine density may be significant for goal-directed exploration and associated long-term memory in mice.

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