title: Hydrocephalus compacted cortex and hippocampus and altered their output neurons in association with spatial learning and memory deficits in rats.
abstract: Hydrocephalus is a common neurological disorder in children characterized by abnormal dilation of cerebral ventricles as a result of the impairment of cerebrospinal fluid flow or absorption. Clinical presentation of hydrocephalus varies with chronicity and often shows cognitive dysfunction. Here we used a kaolin-induction method in rats and studied the effects of hydrocephalus on cerebral cortex and hippocampus, the two regions highly related to cognition. Hydrocephalus impaired rats' performance in Morris water maze task. Serial three-dimensional reconstruction from sections of the whole brain freshly froze in situ with skull shows that the volumes of both structures were reduced. Morphologically, pyramidal neurons of the somatosensory cortex and hippocampus appear to be distorted. Intracellular dye injection and subsequent three-dimensional reconstruction and analyses revealed that the dendritic arbors of layer III and V cortical pyramid neurons were reduced. The total dendritic length of CA1, but not CA3, pyramidal neurons was also reduced. Dendritic spine densities on both cortical and hippocampal pyramidal neurons were decreased, consistent with our concomitant findings that the expressions of both synaptophysin and postsynaptic density protein 95 were reduced. These cortical and hippocampal changes suggest reductions of excitatory connectivity, which could underlie the learning and memory deficits in hydrocephalus.
authors.affiliation: Department of Anatomy, College of Medicine, Tzu-Chi University, Hualien City, Taiwan.
authors.forename: Li-Jin
authors.initials: LJ
authors.lastname: Chen
authors.affiliation: Department of Anatomy, College of Medicine, Tzu-Chi University, Hualien City, Taiwan.
authors.forename: Yueh-Jan
authors.initials: YJ
authors.lastname: Wang
authors.affiliation: Department of Veterinary Medicine, College of Veterinary Medicine, National Chung-Hsing University, Taichung, Taiwan.
authors.forename: Jeng-Rung
authors.identifier: 0000-0002-4429-283X
authors.initials: JR
authors.lastname: Chen
authors.affiliation: Department of Anatomy, College of Medicine, Tzu-Chi University, Hualien City, Taiwan.
authors.forename: Guo-Fang
authors.initials: GF
authors.lastname: Tseng
mesh_terms: D000818:Animals; D000930:Antidiarrheals / Q000633:toxicity; D002540:Cerebral Cortex / Q000473:pathology*; D049229:Dendritic Spines / Q000473:pathology / Q000648:ultrastructure; D004195:Disease Models, Animal; D000076122:Disks Large Homolog 4 Protein / Q000378:metabolism; D006624:Hippocampus / Q000473:pathology*; D006849:Hydrocephalus / Q000139:chemically induced / Q000150:complications* / Q000473:pathology*; D007616:Kaolin / Q000633:toxicity; D018782:Maze Learning; D008569:Memory Disorders / Q000209:etiology*; D009415:Nerve Net / Q000473:pathology; D009474:Neurons / Q000473:pathology / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D065853:Spatial Learning / Q000502:physiology*; D013997:Time Factors
chemical_list: D000930:Antidiarrheals; D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D007616:Kaolin
keywords: cortex; dendritic spine; hippocampus; hydrocephalus; pyramidal neuron