title: Gonadal Hormones Rapidly Enhance Spatial Memory and Increase Hippocampal Spine Density in Male Rats.
abstract: 17β-estradiol (E2) rapidly, within minutes, activates behaviors and cognition by binding to membrane estrogen receptors, activating cell signaling cascades and increasing dendritic spines. In female rodents, E2 enhances spatial memory within 2-4 hours, and spine density is increased in the CA1 area of the hippocampus within 30-60 minutes. Although chronic gonadal hormone treatments in male rats alter cognition and spines/spine synapses and acute hormone effects occur in hippocampal slices, effects of acute, in vivo hormone administration in males are unknown. Therefore, we assessed rapid effects of E2 (20 μg/kg) and testosterone (T) (750 μg/kg) on spatial memory using the object placement task and on hippocampal spine density using Golgi impregnation. Orchidectomized rats received hormones immediately after the training trial and were tested for retention 2 hours later. Vehicle-injected orchidectomized males spent equal time exploring objects in the old and new locations, but E2- or T-treated subjects spent more time exploring objects at the new location, suggesting enhanced memory. Both hormones also increased spine density in CA1, but not the dentate gyrus, by 20%-40% at 30 minutes and 2 hours after injections. This report is the first, to our knowledge, to show E2 and T enhancements of memory and spine density within such a short time frame in male rats.
authors: Department of Psychology (L.F.J., K.B., D.B., F.L., V.N.L.), Hunter College of City University of New York, New York, New York 10021; and Department of Science Education (M.F.), Hofstra North Shore Long Island Jewish School of Medicine, Hempstead, New York 11549.
authors: Luis F
authors: LF
authors: Jacome
authors: Department of Psychology (L.F.J., K.B., D.B., F.L., V.N.L.), Hunter College of City University of New York, New York, New York 10021; and Department of Science Education (M.F.), Hofstra North Shore Long Island Jewish School of Medicine, Hempstead, New York 11549.
authors: Ketti
authors: K
authors: Barateli
authors: Department of Psychology (L.F.J., K.B., D.B., F.L., V.N.L.), Hunter College of City University of New York, New York, New York 10021; and Department of Science Education (M.F.), Hofstra North Shore Long Island Jewish School of Medicine, Hempstead, New York 11549.
authors: Dina
authors: D
authors: Buitrago
authors: Department of Psychology (L.F.J., K.B., D.B., F.L., V.N.L.), Hunter College of City University of New York, New York, New York 10021; and Department of Science Education (M.F.), Hofstra North Shore Long Island Jewish School of Medicine, Hempstead, New York 11549.
authors: Franklin
authors: F
authors: Lema
authors: Department of Psychology (L.F.J., K.B., D.B., F.L., V.N.L.), Hunter College of City University of New York, New York, New York 10021; and Department of Science Education (M.F.), Hofstra North Shore Long Island Jewish School of Medicine, Hempstead, New York 11549.
authors: Maya
authors: M
authors: Frankfurt
authors: Department of Psychology (L.F.J., K.B., D.B., F.L., V.N.L.), Hunter College of City University of New York, New York, New York 10021; and Department of Science Education (M.F.), Hofstra North Shore Long Island Jewish School of Medicine, Hempstead, New York 11549.
authors: Victoria N
authors: VN
authors: Luine
mesh_terms: D000728:Androgens / Q000494:pharmacology; D000818:Animals; D056547:CA1 Region, Hippocampal / Q000187:drug effects* / Q000378:metabolism; D049229:Dendritic Spines / Q000187:drug effects* / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology; D042341:Gonadal Hormones / Q000494:pharmacology*; D008297:Male; D009919:Orchiectomy; D017207:Rats, Sprague-Dawley; D065852:Spatial Memory / Q000187:drug effects*; D013739:Testosterone / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000728:Androgens; D004967:Estrogens; D042341:Gonadal Hormones; D013739:Testosterone; D004958:Estradiol