Regional expression and ultrastructural localization of EphA7 in the hippocampus and cerebellum of adult rat. Issue 12 (26th February 2016)

• Record Type: Journal Article
• Authors: Amegandjin, Clara A.; Jammow, Wafaa; Laforest, Sylvie; Riad, Mustapha; Baharnoori, Moogeh; Badeaux, Frédérique; DesGroseillers, Luc; Murai, Keith K.; Pasquale, Elena B.; Drolet, Guy; Doucet, Guy
• Is Part Of: Journal of comparative neurology. Volume 524:Issue 12(2016)
• Page Start: 2462
• Page End: 2478
• Publication Date: 2016-02-26
• Subjects: Eph receptor -- hippocampus -- cerebellum -- dendritic spines -- astrocytes -- ultrastructure; Comparative neurobiology -- Periodicals; Neurology -- Periodicals; 616
• DOI: 10.1002/cne.23962
• Languages: English
• ISSNs: 0021-9967

Abstract

Abstract : EphA7 is expressed in the adult central nervous system (CNS), where its roles are yet poorly defined. We mapped its distribution using in situ hybridization (ISH) and immunohistochemistry (IHC) combined with light (LM) and electron microscopy (EM) in adult rat and mouse brain. The strongest ISH signal was in the hippocampal pyramidal and granule cell layers. Moderate levels were detected in habenula, striatum, amygdala, the cingulate, piriform and entorhinal cortex, and in cerebellum, notably the Purkinje cell layer. The IHC signal distribution was consistent with ISH results, with transport of the protein to processes, as exemplified in the hippocampal neuropil layers and weakly stained pyramidal cell layers. In contrast, in the cerebellum, the Purkinje cell bodies were the most strongly immunolabeled elements. EM localized the cell surface‐expression of EphA7 essentially in postsynaptic densities (PSDs) of dendritic spines and shafts, and on some astrocytic leaflets, in both hippocampus and cerebellum. Perikaryal and dendritic labeling was mostly intracellular, associated with the synthetic and trafficking machineries. Immunopositive vesicles were also observed in axons and axon terminals. Quantitative analysis in EM showed significant differences in the frequency of labeled elements between regions. Notably, labeled dendrites were ∼3–5 times less frequent in cerebellum than in hippocampus, but they were individually endowed with ∼10–40 times higher frequencies of PSDs, on their shafts and spines. The cell surface localization of EphA7, being preferentially in PSDs, and in perisynaptic astrocytic leaflets, provides morphologic evidence that EphA7 plays key roles in adult CNS synaptic maintenance, plasticity, or function. J. Comp. Neurol. 524:2462–2478, 2016. © 2016 Wiley Periodicals, Inc. Abstract : EphA7 is localized in post‐synaptic densities of dendritic spines and shafts, on astrocytic leaflets and on vesicles and synaptic surface of axonal terminals, but rarely found altogether on all three locations of a single synapse, in single thin sections. Thus, EphA7 appears to play diverse roles at different synaptic contacts.