title: DHEA prevents Aβ25-35-impaired survival of newborn neurons in the dentate gyrus through a modulation of PI3K-Akt-mTOR signaling.
abstract: Infusion (i.c.v.) of beta-amyloid 25-35 (Abeta(25-35)) stimulates proliferation of progenitor cells in the hippocampal dentate gyrus (DG) of adult male mice, but a large population of the newborn cells will die in the 2nd week after birth, a critical period for neurite growth. Neurosteroid dehydroepiandrosterone (DHEA) has been demonstrated to promote neurite growth. Herein, we report that the DHEA-treatment on 6-12 days after BrdU-injection (BrdU-D(6-12)) dose-dependently attenuates the loss of newborn neurons induced by Abeta(25-35)-infusion. The DHEA-neuroprotection was blocked by the sigma(1) receptor antagonist NE100 and mimicked by the sigma(1) receptor agonist PRE084 when administered on BrdU-D(6-12). The DHEA-action was sensitive to the PI3K inhibitor LY294002 and the mammalian target of rapamycin (mTOR) inhibitor rapamycin. The Abeta(25-35)-infusion decreased the levels of Akt, mTOR and p70S6k phosphorylation, which could be rescued by DHEA-treatment in a sigma(1) receptor-dependent manner. Furthermore, the Abeta(25-35)-infusion led to a decrease in the dendritic density and length of doublecortin positive cells in the DG, which also was improved by the DHEA-treatment on BrdU-D(6-12). These findings suggest that DHEA prevents the Abeta(25-35)-impaired survival and dendritic growth of newborn neurons through a sigma(1) receptor-mediated modulation of PI3K-Akt-mTOR-p70S6k signaling.
authors.affiliation: Department of Physiology, Nanjing Medical University, Jiangsu, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Li
authors.forename: Bingzhong
authors.initials: B
authors.lastname: Xu
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhu
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: Masahiro
authors.initials: M
authors.lastname: Sokabe
authors.forename: Ling
authors.initials: L
authors.lastname: Chen
mesh_terms: D016229:Amyloid beta-Peptides / Q000037:antagonists & inhibitors / Q000633:toxicity*; D000818:Animals; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D003687:Dehydroepiandrosterone / Q000494:pharmacology*; D018891:Dentate Gyrus / Q000187:drug effects / Q000473:pathology / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D055495:Neurogenesis / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000473:pathology / Q000502:physiology*; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000633:toxicity*; D058539:Phosphatidylinositol 3-Kinase / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D058570:TOR Serine-Threonine Kinases / Q000502:physiology*
chemical_list: D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; C074636:amyloid beta-protein (25-35); D003687:Dehydroepiandrosterone; C546843:mTOR protein, mouse; D058539:Phosphatidylinositol 3-Kinase; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases