Naslov
Development and plasticity of the hippocampal dentate gyrus

Autori
Vukšić, Mario

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Neurogenomics and neuroimaging of developmental disorders / IBRO - Zagreb : Depol Komunikacije, 2009, 57-58

Skup
Neurogenomics and neuroimaging of developmental disorders

Mjesto i datum
Dubrovnik, Hrvatska, 30.04.2009. - 05.05.2009

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
development; regeneration; mouse dentate gyrus; confocal microscopy; morphometry;

Sažetak
The dentate gyrus (DG) is a three-dimensionally curved structure composed of a compact layer containing densely packed granule cells. Their dendrites extend from the apical pole into the overlying molecular layer, and the axon, or mossy fiber, exists from the basal pole. The axon gives rise to collateral branches in the hilar region and then forms synapses on pyramidal neurons in the CA3 region of the hippocampus proper. The DG is the first stage of the intrahippocampal, excitatory, trisynaptic loop, and a primary target of the majority of entorhinal afferents that terminate in a laminar fashion on granule cell dendrites and carry sensory information of multiple modalities about the external world. When compared to other brain regions, which largely develop prenatally, the DG is characterized by an ongoing postnatal development. It is one of the small numbers of forebrain areas that have continued adult neurogenesis. It has been a focus of recent studies how postnatal granule cell formation can be modified by external stimuli and how the newly generated granule cells become integrated into the mature network of the DG. One of the more remarkable characteristics of the DG is its plasticity. In addition to the phenomenon of adult granule cell neurogenesis, other plastic changes are observed at granule cell synapses, such as LTP, LTD, or the formation of new synaptic contacts that together have the potential to contribute to accurate and efficient information storage within the hippocampal formation. Due to its relatively simple cytoarchitecture and the laminated termination of afferent fiber systems the DG has been frequently used as a model system to analyze normal as well as pathological processes of the brain. One of the classical model system used to study lesion-induced plasticity is the reorganization of the DG following entorhinal cortex lesion (ECL). Although this experimental model has been extensively characterized in the rat, data on the reorganization in the denervated mouse DG are scarce. Since this limits the use of genetic tools, we have analyzed the dendritic reorganization of denervated granule cells in Thy-1 GFP transgenic mice. Single GFP-labeled granule cells were 3D-reconstructed in their entirety using confocal microscopy and Neurolucida software at different time points upon denervation. Following unilateral ECL granule cells underwent morphological changes. These included changes in dendritic arborization (reduction of dendritic length and complexity) as well as changes in the density of spines on dendrites maintained by granule cells after denervation. Changes in dendritic arborization were first observed around 7 days post lesion (dpl) and progressed for several weeks. The most severe changes were observed 90 dpl and after long survival times (180 dpl) a partial reconstruction of the dendritic tree was observed. Changes in spine density preceded the alterations in dendritic arborization (3 dpl), these were most pronounced at 90 dpl and by 180 dpl only partial recovery was observed. Taken together, ECL in mice results in long-lasting dendritic atrophy, which suggests that sprouting of unlesioned fibers may halt the atrophic degeneration but obviously can not reverse it.

Izvorni jezik
Engleski

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