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NEUROSTRUCTURAL.COMdetailed morphometric studies of dendritic branching and spines to assess the integrity of neural circuitry
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How It Works and What We Do.
Camera lucida drawing and computer generated Sholl overlay for analysis of human cortical pyramidal neuron.
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Using formalin fixed brain tissue sent to our lab,
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Evaluating the Amount of Dendritic Branching from Golgi-Stained Neurons.
Example 1: Dendritic Alterations in an Animal Model of Alzheimer’s Disease.
Photomicrograph of a hippocampal CA1 pyramid from a wild type control
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Camera lucida drawings of CA1 basilar trees from normal wild type mouse
Camera lucida drawings of a mouse model of Alzheimer’s Disease, a transgenic Arc A-beta mouse.
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Comparison of the Sholl profiles of the CA1s from the two groups clearly demonstrates that the dendritic arbor of the tg mouse is significantly less than that of the age-matched wild type control. There were 6 subjects (and 29 neurons evaluated) in the WT group; and 5 subjects (and 25 neurons evaluated) in the transgenic AD group.
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Comparison of the complexity of the dendritic fields of the CA1s also shows reduction of complexity in this mouse model of AD. The graph above compares the complexity of CA1 basilar dendritic trees from 3 month-old wild type control mice (blue) vs CA1s from an age-matched Arc A-beta mouse model of AD (red). The neurons from the AD mouse model have significantly fewer branch points than the WT controls; as such, the dendritic arbor of the AD mouse CA1s is less complex.
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Example 2: Environmental and Dietary Studies - A Blueberry-Enriched Diet
Reverses age-related neocortical dendritic branch loss in old rats
The graph above shows how dietary ingredients can influence dendritic branching – in this case, the effects of a blueberry enriched diet on age-related changes of neurons in the rat neocortex. The Sholl graph below demonstrates that there is a significant decrease in dendritic branching with normal aging (young control profile [top] vs. the old control [bottom]). Treatment of older rats with a blueberry-enriched diet for 3 months increased the amount of the dendritic branching in the cortical pyramids (middle profile) such that it was now not significantly less than in the young mice.
Representative photomicrographs of layer II/III pyramids of the parietal cortex (basilar tree)
(basilar tree) from an old control rat
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(basilar tree) from an old age-matched rat which had received a blueberry enriched diet
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Representative photomicrographs of layer II/III pyramids of the parietal cortex (basilar tree) from an old control rat (left) and from an old age-matched rat which had received a blueberry enriched diet (right).
Example 3: Neurotoxicology Studies
Neonatal exposure to PCBs results in reduced dendritic arbor in hippocampal CA1s of 22 do rat pups.
Neonatal Exposure to PCBs results in early – but reversible – damage to Purkinje Cells of the Cerebellum of the Rat
Appearance of Golgi stained Purkinje cells in Rat Cerebellum
A. Measurement of area of representative Purkinje Cell dendritic arbor (22 days-old).
B. Purkinje cell arbor of 22 day-old rats exposed to PCB is significantly smaller than age-matched controls.
C. Dendritic arbor of Purkinje cell from adult (60 day-old) rat cerebellum.
D. Purkinje cell dendritic arbor of 60 day old rat which had been exposed neonatally to PCBs.
B. Purkinje cell arbor of 22 day-old rats exposed to PCB is significantly smaller than age-matched controls.
C. Dendritic arbor of Purkinje cell from adult (60 day-old) rat cerebellum.
D. Purkinje cell dendritic arbor of 60 day old rat which had been exposed neonatally to PCBs.
Example 4. Neuropathology.
Normal appearing hippocampal CA1 from non-cognitively impaired 80 year old.
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Atrophic CA1 pyramid seen in autopsied hippocampal tissue from Alzheimer brain (86 years old).
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DENDRITIC SPINE ANALYSIS
Our Dendritic Spine Analysis Studies include
- Spine Density
- Spine Configurations
- Soma size
Example 1: Reduction of Dendritic Spines in Hyperglycemic Rats
The graph below shows the spine density on granule cells of the rat dentate gyrus. Hyperglycemic rats show significant spine loss compared to controls and hypoglycemic rats.
The photomicrographs below show the appearance of spines from controls and hyperglycemic rats:
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Example 2: Loss of Dendritic Spines in the Progression of Alzheimer’s DiseaseThe photomicrographs below show our Golgi studies can demonstrate the progression of spine loss in the human temporal cortex in the evolution of Alzheimer’s disease…from Normal Aging (Non-Cognitively Impaired) to Mild Cognitive Impairment to full-blown Alzheimer’s Disease.
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Normal Aging (Non-Cognitively Impaired)
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Mild Cognitive Impairment (MCI)
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Alzheimer’s Disease
The impact of the progression of AD on dendritic spines in the temporal cortex is summarized in the accompanying graph (below)
Progressive Spine Loss in the Evolution of Alzheimer’s Disease
Example 3: Extrinsic Influences on Dendritic Spines Loss of Specific Spine Types After Exposure to Heavy Particle Radiation
M-Type Spines (mushroom-type spines) are decreased in both Granule Cells of the Dentate Gyrus (upper graph) and on CA1 pyramids of the Hippocampus (lower graph) in Rats following exposure to (56)Fe.
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CA1 pyramids: loss of M-type spines (% change from control)
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Example 4: Traumatic Brain Injury
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Example 5. Cerebral Ischemia
Appearance of dysmorphic dendritic spines in penumbra of an animal model of middle cerebral arterial occlusion (MCAO). Note the appearance of numerous long filopodia-like spines.
