title: Extracellular matrix molecules and synaptic plasticity: immunomapping of intracellular and secreted Reelin in the adult rat brain.
abstract: Reelin, a large extracellular matrix glycoprotein, is secreted by several neuron populations in the developing and adult rodent brain. Secreted Reelin triggers a complex signaling pathway by binding lipoprotein and integrin membrane receptors in target cells. Reelin signaling regulates migration and dendritic growth in developing neurons, while it can modulate synaptic plasticity in adult neurons. To identify which adult neural circuits can be modulated by Reelin-mediated signaling, we systematically mapped the distribution of Reelin in adult rat brain using sensitive immunolabeling techniques. Results show that the distribution of intracellular and secreted Reelin is both very widespread and specific. Some interneuron and projection neuron populations in the cerebral cortex contain Reelin. Numerous striatal neurons are weakly immunoreactive for Reelin and these cells are preferentially located in striosomes. Some thalamic nuclei contain Reelin-immunoreactive cells. Double-immunolabeling for GABA and Reelin reveals that the Reelin-immunoreactive cells in the visual thalamus are the intrinsic thalamic interneurons. High local concentrations of extracellular Reelin selectively outline several dendrite spine-rich neuropils. Together with previous mRNA data, our observations suggest abundant axoplasmic transport and secretion in pathways such as the retino-collicular tract, the entorhino-hippocampal ('perforant') path, the lateral olfactory tract or the parallel fiber system of the cerebellum. A preferential secretion of Reelin in these neuropils is consistent with reports of rapid, activity-induced structural changes in adult brain circuits.
authors.affiliation: Department of Anatomy and Neuroscience, School of Medicine, Autónoma University, Ave. Arzobispo Morcillo s/n., Madrid 28029, Spain.
authors.forename: Tania
authors.initials: T
authors.lastname: Ramos-Moreno
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Galazo
authors.forename: Cesar
authors.initials: C
authors.lastname: Porrero
authors.forename: Verónica
authors.initials: V
authors.lastname: Martínez-Cerdeño
authors.forename: Francisco
authors.initials: F
authors.lastname: Clascá
mesh_terms: D000818:Animals; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000166:cytology / Q000378:metabolism; D001931:Brain Mapping; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism*; D003952:Diagnostic Imaging / Q000379:methods; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005260:Female; D042541:Intracellular Space / Q000378:metabolism*; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009473:Neuronal Plasticity; D009474:Neurons / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D000091042:Reelin Protein; D012697:Serine Endopeptidases / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; D016326:Extracellular Matrix Proteins; D009419:Nerve Tissue Proteins; D000091042:Reelin Protein; C000717129:Reln protein, rat; D005680:gamma-Aminobutyric Acid; D012697:Serine Endopeptidases