title: Antidepressant-induced vascular dynamics in the hippocampus of adult mouse brain.
abstract: New neurons are continuously added to hippocampal circuitry involved with spatial learning and memory throughout life. These new neurons originate from neural stem/progenitor cells (NSPCs) in the subgranular zone (SGZ) of the dentate gyrus (DG). Recent studies indicate that vascular reconstruction is closely connected with neurogenesis, but little is known about its mechanism. We have examined vascular reconstruction in the hippocampus of adult mouse brain after the administration of the antidepressant fluoxetine, a potent inducer of hippocampal neurogenesis. The immunohistochemistry of laminin and CD31 showed that filopodia of endothelial cells sprouted from existing thick microvessels and often formed a bridge between two thick microvessels. These filopodia were frequently seen at the molecular layer and dentate hilus of the DG, the stratum lacunosum-moleculare of the CA1, and the stratum oriens of the CA3. The filopodia were exclusively localized along cellular processes of astrocytes, but such intimate association was not seen with cell bodies and processes of NSPCs. The administration of fluoxetine significantly increased vascular density by enlarging the luminal size of microvessels and eliminating the filopodia of endothelial cells in the molecular layer and dentate hilus. Treatment with fluoxetine increased the number of proliferating NSPCs in the granule cell layer and dentate hilus, and that of endothelial cells in the granule cell layer. Thus, antidepressant-induced vascular dynamics in the DG are possibly attributable to the alteration of the luminal size of microvessels rather than to proliferation of endothelial cells.
authors: Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan.
authors: Tetsuya
authors: T
authors: Mannari
authors: Hayato
authors: H
authors: Sawa
authors: Eriko
authors: E
authors: Furube
authors: Shohei
authors: S
authors: Fukushima
authors: Kazunori
authors: K
authors: Nishikawa
authors: Toshihiro
authors: T
authors: Nakashimna
authors: Seiji
authors: S
authors: Miyata
mesh_terms: D000818:Animals; D018687:Antidepressive Agents, Second-Generation / Q000494:pharmacology*; D056654:CA3 Region, Hippocampal / Q000098:blood supply / Q000166:cytology / Q000382:microbiology; D049109:Cell Proliferation / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D018891:Dentate Gyrus / Q000098:blood supply / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology; D005473:Fluoxetine / Q000494:pharmacology*; D007797:Laminin / Q000096:biosynthesis; D008297:Male; D051379:Mice; D055806:Microvessels / Q000378:metabolism; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000096:biosynthesis
chemical_list: D018687:Antidepressive Agents, Second-Generation; D007797:Laminin; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D005473:Fluoxetine