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A stereological study of synapse number in the epileptic human hippocampus.

Alonso-Nanclares L, Kastanauskaite A, Rodriguez JR, Gonzalez-Soriano J, Defelipe J - Front Neuroanat (2011)

Bottom Line: Specifically, we examined the possible changes in the subiculum and CA1, regions that seem to be critical for the development and/or maintenance of seizures in these patients.We found a remarkable decrease in synaptic and neuronal density in the sclerotic CA1, and while the subiculum from the sclerotic hippocampus did not display changes in synaptic density, the neuronal density was higher.Since the subiculum from the sclerotic hippocampus displays a significant increase in neuronal density, as well as a various other neurochemical changes, we propose that the apparently normal subiculum from the sclerotic hippocampus suffers profound alterations in neuronal circuits at both the molecular and synaptic level that are likely to be critical for the development or maintenance of seizure activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Functional and Systems Neurobiology, Instituto Cajal (Consejo Superior de Investigaciones Cientificas) Madrid, Spain.

ABSTRACT
Hippocampal sclerosis is the most frequent pathology encountered in resected mesial temporal structures from patients with intractable temporal lobe epilepsy (TLE). Here, we have used stereological methods to compare the overall density of synapses and neurons between non-sclerotic and sclerotic hippocampal tissue obtained by surgical resection from patients with TLE. Specifically, we examined the possible changes in the subiculum and CA1, regions that seem to be critical for the development and/or maintenance of seizures in these patients. We found a remarkable decrease in synaptic and neuronal density in the sclerotic CA1, and while the subiculum from the sclerotic hippocampus did not display changes in synaptic density, the neuronal density was higher. Since the subiculum from the sclerotic hippocampus displays a significant increase in neuronal density, as well as a various other neurochemical changes, we propose that the apparently normal subiculum from the sclerotic hippocampus suffers profound alterations in neuronal circuits at both the molecular and synaptic level that are likely to be critical for the development or maintenance of seizure activity.

No MeSH data available.


Related in: MedlinePlus

(A) Low-power photomicrograph of a Nissl-stained section to illustrate an sclerotic hippocampus at the level of the medial hippocampal formation. In all cases, the tissue used corresponded to a similar level. (B,C) Photomicrographs of Nissl-stained sections of a non-sclerotic (B) and a sclerotic hippocampal formation (C) illustrating the regions examined in the present study (indicated by boxes). CA1–3: cornu ammonis fields; DG, dentate gyrus; Sub, subiculum, Sub/CA1: transitional subiculum/CA1 region. Scale bar [in (B)]: 500 μm in (A), 1000 μm in (B,C).
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Figure 1: (A) Low-power photomicrograph of a Nissl-stained section to illustrate an sclerotic hippocampus at the level of the medial hippocampal formation. In all cases, the tissue used corresponded to a similar level. (B,C) Photomicrographs of Nissl-stained sections of a non-sclerotic (B) and a sclerotic hippocampal formation (C) illustrating the regions examined in the present study (indicated by boxes). CA1–3: cornu ammonis fields; DG, dentate gyrus; Sub, subiculum, Sub/CA1: transitional subiculum/CA1 region. Scale bar [in (B)]: 500 μm in (A), 1000 μm in (B,C).

Mentions: In this study, we established the cytoarchitectonic division of the hippocampal fields on the basis of previous descriptions (Amaral et al., 1990). The distinction between CA1 and subiculum was established by the clusters of modified pyramidal cells in the superficial aspect of the subiculum (the nomenclature used for each region examined is shown in Figure 1; according to Muñoz et al., 2007). Both in the non-sclerotic and sclerotic hippocampus, the area of the subiculum displayed an apparent normal aspect and is referred to as subiculum from non-sclerotic and from sclerotic hippocampi respectively, while the areas of the CA1 showing clear neuronal loss and gliosis will be referred to as the sclerotic CA1. Since the transition between the subiculum and CA1 is gradual and diffuse, this region is referred to as the transitional subiculum/CA1, and it was only contemplated for analysis in the sclerotic hippocampus (Figures 1 and 2).


A stereological study of synapse number in the epileptic human hippocampus.

Alonso-Nanclares L, Kastanauskaite A, Rodriguez JR, Gonzalez-Soriano J, Defelipe J - Front Neuroanat (2011)

(A) Low-power photomicrograph of a Nissl-stained section to illustrate an sclerotic hippocampus at the level of the medial hippocampal formation. In all cases, the tissue used corresponded to a similar level. (B,C) Photomicrographs of Nissl-stained sections of a non-sclerotic (B) and a sclerotic hippocampal formation (C) illustrating the regions examined in the present study (indicated by boxes). CA1–3: cornu ammonis fields; DG, dentate gyrus; Sub, subiculum, Sub/CA1: transitional subiculum/CA1 region. Scale bar [in (B)]: 500 μm in (A), 1000 μm in (B,C).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3046382&req=5

Figure 1: (A) Low-power photomicrograph of a Nissl-stained section to illustrate an sclerotic hippocampus at the level of the medial hippocampal formation. In all cases, the tissue used corresponded to a similar level. (B,C) Photomicrographs of Nissl-stained sections of a non-sclerotic (B) and a sclerotic hippocampal formation (C) illustrating the regions examined in the present study (indicated by boxes). CA1–3: cornu ammonis fields; DG, dentate gyrus; Sub, subiculum, Sub/CA1: transitional subiculum/CA1 region. Scale bar [in (B)]: 500 μm in (A), 1000 μm in (B,C).
Mentions: In this study, we established the cytoarchitectonic division of the hippocampal fields on the basis of previous descriptions (Amaral et al., 1990). The distinction between CA1 and subiculum was established by the clusters of modified pyramidal cells in the superficial aspect of the subiculum (the nomenclature used for each region examined is shown in Figure 1; according to Muñoz et al., 2007). Both in the non-sclerotic and sclerotic hippocampus, the area of the subiculum displayed an apparent normal aspect and is referred to as subiculum from non-sclerotic and from sclerotic hippocampi respectively, while the areas of the CA1 showing clear neuronal loss and gliosis will be referred to as the sclerotic CA1. Since the transition between the subiculum and CA1 is gradual and diffuse, this region is referred to as the transitional subiculum/CA1, and it was only contemplated for analysis in the sclerotic hippocampus (Figures 1 and 2).

Bottom Line: Specifically, we examined the possible changes in the subiculum and CA1, regions that seem to be critical for the development and/or maintenance of seizures in these patients.We found a remarkable decrease in synaptic and neuronal density in the sclerotic CA1, and while the subiculum from the sclerotic hippocampus did not display changes in synaptic density, the neuronal density was higher.Since the subiculum from the sclerotic hippocampus displays a significant increase in neuronal density, as well as a various other neurochemical changes, we propose that the apparently normal subiculum from the sclerotic hippocampus suffers profound alterations in neuronal circuits at both the molecular and synaptic level that are likely to be critical for the development or maintenance of seizure activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Functional and Systems Neurobiology, Instituto Cajal (Consejo Superior de Investigaciones Cientificas) Madrid, Spain.

ABSTRACT
Hippocampal sclerosis is the most frequent pathology encountered in resected mesial temporal structures from patients with intractable temporal lobe epilepsy (TLE). Here, we have used stereological methods to compare the overall density of synapses and neurons between non-sclerotic and sclerotic hippocampal tissue obtained by surgical resection from patients with TLE. Specifically, we examined the possible changes in the subiculum and CA1, regions that seem to be critical for the development and/or maintenance of seizures in these patients. We found a remarkable decrease in synaptic and neuronal density in the sclerotic CA1, and while the subiculum from the sclerotic hippocampus did not display changes in synaptic density, the neuronal density was higher. Since the subiculum from the sclerotic hippocampus displays a significant increase in neuronal density, as well as a various other neurochemical changes, we propose that the apparently normal subiculum from the sclerotic hippocampus suffers profound alterations in neuronal circuits at both the molecular and synaptic level that are likely to be critical for the development or maintenance of seizure activity.

No MeSH data available.


Related in: MedlinePlus