title: [The influence of severe long-term exercise on the mouse hippocampus].
abstract: To determine whether severe long-term exercise affects on the brain, we investigated the mice brain after 12-week treadmill exercise. The mice (ddN, male, 25-35 g in body weight) were divided into severe, mild, and non-exercise group. Mice in severe groups ran on a treadmill at a speed of 25 m/min for 12 weeks and mice in mild group ran on a treadmill at a speed of 10 m/min for 12 weeks. The mice were killed by transcardial perfusion with 0.1 M phosphate-buffered saline (PBS) followed by ice-cold 4% paraformaldehyde in 0.1 M PB. The another sets of mice were fixed by 2.5% glutaraldehyde-2% osmium tetroxide for electromicroscope (EM). The brains were serially sectioned in the coronal plane at a thickness of 20-microns with a vibratome and then processed for histology, by means of hematoxylin-eosin (HE) staining and immunohistochemistry. Fifty % of mice in severe exercise showed hyperchromatic and shrunken nerve cells with nuclear pyknosis (dark neuron) in the hippocampus, but not in mild exercise and non-exercise groups. The immunoreactivity of microtuble associated protein-2 (MAP-2) decreased, while the heat-shock protein/cognate 70 (HSP/C 70) increased in the hippocampus of severe exercise group. Many destroyed mitochondria were observed in dark neurons by Electron micrograph. These findings suggested that severe long-term exercise might damage hippocampal neurons.
authors.affiliation: Department of Basic Sports Medicine, Kagawa Medical University, 1750-1, Ikenobe, Miki-sho, Kita-gun, Kagawa 761-0793, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Sumitani
authors.forename: Osamu
authors.initials: O
authors.lastname: Miyamoto
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yamagami
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Okada
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Itano
authors.forename: Tetuhide
authors.initials: T
authors.lastname: Murakami
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Negi
mesh_terms: D000818:Animals; D001835:Body Weight; D006360:Heat-Shock Proteins / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D019344:Lactic Acid / Q000097:blood; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008928:Mitochondria / Q000473:pathology; D018384:Oxidative Stress / Q000502:physiology; D010805:Physical Conditioning, Animal / Q000009:adverse effects*; D013997:Time Factors
chemical_list: D006360:Heat-Shock Proteins; D008869:Microtubule-Associated Proteins; D019344:Lactic Acid