title: Estradiol treatment in preadolescent females enhances adolescent spatial memory and differentially modulates hippocampal region-specific phosphorylated ERK labeling.
abstract: Estrogen levels in rats are positively correlated with enhanced memory function and hippocampal dendritic spine density. There is much less work on the long-term effects of estradiol manipulation in preadolescent rats. The present work examined how injections of estradiol during postnatal days 19-22 (p19-22; preadolescence) affected water maze performance and hippocampal phosphorylated ERK labeling. To investigate this, half of the estradiol- and vehicle-treated female rats were trained on a water maze task 24h after the end of estradiol treatment (p23-27) while the other half was not trained. All female rats were tested on the water maze from p40 to p44 (adolescence) and hippocampal pERK1/2 labeling was assessed as a putative marker of neuronal plasticity. During adolescence, preadolescent-trained groups showed lower latencies than groups without preadolescent training. Retention data revealed lower latencies in both estradiol groups, whether preadolescent trained or not. Immunohistochemical detection of hippocampal pERK1/2 revealed elevations in granule cell labeling associated with the preadolescent trained groups and reductions in CA1 labeling associated with estradiol treatment. These results show a latent beneficial effect of preadolescent estradiol treatment on adolescent spatial performance and suggest an organizational effect of prepubescent exogenously applied estradiol.
authors.affiliation: Carleton University, Department of Neuroscience Ottawa, Ontario K1S 5B6 Canada.
authors.forename: Brianne C
authors.initials: BC
authors.lastname: Wartman
authors.forename: Robin J
authors.initials: RJ
authors.lastname: Keeley
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Holahan
mesh_terms: D000367:Age Factors; D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D006624:Hippocampus / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D018782:Maze Learning / Q000187:drug effects; D008568:Memory / Q000187:drug effects*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009473:Neuronal Plasticity; D009949:Orientation / Q000187:drug effects*; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar
chemical_list: D004967:Estrogens; D004958:Estradiol; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3