title: Effects of running exercise during recovery from hindlimb unloading on soleus muscle fibers and their spinal motoneurons in rats.
abstract: The effects of hindlimb unloading and recovery with or without running exercise on morphological and metabolic properties of soleus muscle fibers and their spinal motoneurons in rats were investigated. Ten-week-old rats were hindlimb suspended for 2 weeks and thereafter were rehabilitated with or without voluntary running exercise for 2 weeks. A decreased percentage of type I fibers and atrophy of all types of fibers were observed after hindlimb unloading. In addition, decreased oxidative enzyme activity of all types of fibers was observed after hindlimb unloading. In contrast, an improvement in the decreased percentage of type I fibers, decreased fiber cross-sectional area, and decreased fiber oxidative enzyme activity was observed after recovery with running exercise, but not without running exercise. There were no changes in the number, cell body size, or oxidative enzyme activity of motoneurons innervating the soleus muscle after hindlimb unloading or recovery with or without running exercise. These results indicate that running exercise is beneficial for the recovery of the decreased percentage of type I fibers and the atrophy and decreased oxidative enzyme activity of all types of fibers in the soleus muscle induced by hindlimb unloading and that there are no changes in morphological or metabolic properties of spinal motoneurons innervating the soleus muscle following decreased or increased neuromuscular activity.
authors.affiliation: Laboratory of Neurochemistry, Graduate School of Human and Environmental Studies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan. ishihara@life.h.kyoto-u.ac.jp
authors.forename: Akihiko
authors.initials: A
authors.lastname: Ishihara
authors.forename: Fuminori
authors.initials: F
authors.lastname: Kawano
authors.forename: Noriaki
authors.initials: N
authors.lastname: Ishioka
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Oishi
authors.forename: Akira
authors.initials: A
authors.lastname: Higashibata
authors.forename: Toru
authors.initials: T
authors.lastname: Shimazu
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Ohira
mesh_terms: D000818:Animals; D048429:Cell Size / Q000502:physiology; D019417:Hindlimb Suspension / Q000502:physiology*; D008297:Male; D009046:Motor Neurons / Q000473:pathology / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000473:pathology / Q000502:physiology*; D018482:Muscle, Skeletal / Q000473:pathology / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012420:Running / Q000502:physiology*