title: Postnatal development of Homer1a in the rat hippocampus.
abstract: Homer1a (H1a) is an immediate early gene involved in multiple forms of synaptic plasticity. It exhibits a postnatal increase in the rat forebrain (Brakeman et al. (1997) Nature 386:284-288) and reduces the density and size of dendritic spines in hippocampal neurons (Sala et al. (2003) J Neurosci 23:6327-6337). We evaluated hippocampal H1a expression at different postnatal ages (P3, P5, P7, P9, P15, P19, P23, P35, and adult) using Fluorescence In Situ Hybridization (FISH) and qRT-PCR. Maximal electroconvulsive shock (MECS) was used to induce maximal expression relative to home cage (HC) controls. Large scale images and confocal z-stacks from dorsal subiculum (DS), CA1, CA3, and dentate gyrus (DG) were analyzed by both manual and automated methods. In DS, CA1, and CA3 a significant proportion of cells (40%) expressed small but detectable levels of H1a from P3; however, MECS did not up-regulate H1a during the first postnatal week. MECS induced H1a positive cells during the second postnatal week and induction reached adult levels at P9. H1a-Intra Nuclear Foci (INF) size and intensity varied with age, increasing at P19-23 in CA1 and CA3 and from P9 to P23 in DS. In DG, H1a expression exhibited a lamination pattern and an H1a-INF size and intensity gradient across the granule cell layer, consistent with the outside-in maturation of DG granule cells. The developmental progression of H1a corresponds to the synaptic refinement period supporting the conclusion that H1a could play an important role in this process.
authors.affiliation: Department of Neuroscience, Canadian Centre for Behavioural Neuroscience, The University of Lethbridge, Lethbridge, AB, T1K 3M4, Canada.
authors.forename: Corinne J
authors.initials: CJ
authors.lastname: Montes-Rodríguez
authors.forename: Valérie
authors.initials: V
authors.lastname: Lapointe
authors.forename: Vivek
authors.initials: V
authors.lastname: Trivedi
authors.forename: Qian
authors.initials: Q
authors.lastname: Lu
authors.forename: Aubrey M
authors.initials: AM
authors.lastname: Demchuk
authors.forename: Bruce L
authors.initials: BL
authors.lastname: McNaughton
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism* / Q000648:ultrastructure; D002540:Cerebral Cortex / Q000648:ultrastructure; D018891:Dentate Gyrus / Q000378:metabolism / Q000648:ultrastructure; D004597:Electroshock / Q000295:instrumentation / Q000379:methods; D005260:Female; D018507:Gene Expression Regulation, Developmental; D017781:Genes, Immediate-Early; D006624:Hippocampus / Q000378:metabolism* / Q000648:ultrastructure; D000072233:Homer Scaffolding Proteins; D042581:Intranuclear Space / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D009473:Neuronal Plasticity / Q000235:genetics / Q000502:physiology*; D057907:Post-Synaptic Density / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats
chemical_list: D002352:Carrier Proteins; D000072233:Homer Scaffolding Proteins
keywords: INF-size and intensity; MECS; activity dependent; immediate early genes; synaptic maturation; synaptic plasticity