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PLoS One. 2016 Oct 31;11(10):e0165752. doi: 10.1371/journal.pone.0165752. eCollection 2016.

A Single Postnatal Dose of Dexamethasone Enhances Memory of Rat Pups Later in Life.

Tsai KJ1,2, Sze CI3, Lin YC4,5, Lin YJ4,5, Hsieh TH4,5, Lin CH4,5.

Author information

1
Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
2
Center of Clinical Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
3
Department of Pathology and Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
4
Department of Pediatrics, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
5
Department of Pediatrics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.

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.

PMID:
27798707
PMCID:
PMC5087852
DOI:
10.1371/journal.pone.0165752
[Indexed for MEDLINE]
Free PMC Article

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