title: A Single Postnatal Dose of Dexamethasone Enhances Memory of Rat Pups Later in Life.
abstract: Postnatal dexamethasone (Dex) therapy is associated with adverse neurodevelopmental outcomes, which might be related to its timing of administration. We used time-dated pregnant Wistar albino rats, whose litters were divided into experimental (Dex) and control groups intraperitoneally administered one dose of Dex (0.5 mg/kg) or normal saline (NS), respectively, at either day 1 (P1) or 7 (P7). The magnitude of the contextual freezing response and performance on the Morris water maze were significantly higher in the Dex-P7 group than in those of the other groups at P56. Dendritic spine density, membranous expression of the N-methyl-d-aspartate receptor (NMDAR) subunit NR2A/2B, and postsynaptic density-95 (PSD-95) were significantly higher in the Dex-P7 group than in the other groups. Furthermore, cytosolic expression of nuclear factor kappa B (NF-κB) and phosphatidylinositol 3-kinase (PI3K) was significantly higher in the Dex group than in NS group. Moreover, Dex administration at P7 increased cell proliferation, neuronal differentiation, and the survival of newly born neurons in the dentate gyrus. These results suggest Dex at P7 enhances the acquisition of contextual fear and spatial memory later in life due to the modulation of the newly born neurons, increase in dendritic spine number, and NMDAR expression.
authors: Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.|Center of Clinical Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors: Kuen-Jer
authors: KJ
authors: Tsai
authors: Department of Pathology and Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors: Chun-I
authors: CI
authors: Sze
authors: Department of Pediatrics, College of Medicine, National Cheng Kung University, Tainan, Taiwan.|Department of Pediatrics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors: Yung-Chieh
authors: YC
authors: Lin
authors: Department of Pediatrics, College of Medicine, National Cheng Kung University, Tainan, Taiwan.|Department of Pediatrics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors: Yuh-Jyh
authors: YJ
authors: Lin
authors: Department of Pediatrics, College of Medicine, National Cheng Kung University, Tainan, Taiwan.|Department of Pediatrics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors: Ting-Hui
authors: TH
authors: Hsieh
authors: Department of Pediatrics, College of Medicine, National Cheng Kung University, Tainan, Taiwan.|Department of Pediatrics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors: Chyi-Her
authors: CH
authors: Lin
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002470:Cell Survival / Q000187:drug effects; D003213:Conditioning, Psychological / Q000187:drug effects; D003712:Dendrites / Q000187:drug effects; D018891:Dentate Gyrus / Q000187:drug effects / Q000378:metabolism; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology*; D000076122:Disks Large Homolog 4 Protein; D005260:Female; D015870:Gene Expression; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D018782:Maze Learning / Q000187:drug effects; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008568:Memory / Q000187:drug effects*; D016328:NF-kappa B / Q000378:metabolism; D055495:Neurogenesis / Q000187:drug effects; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011247:Pregnancy; D011597:Psychomotor Performance / Q000187:drug effects; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D003907:Dexamethasone; D000076122:Disks Large Homolog 4 Protein; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D016328:NF-kappa B; D019869:Phosphatidylinositol 3-Kinases; D016194:Receptors, N-Methyl-D-Aspartate; C501449:Dlg4 protein, rat