title: Effects of unilateral and bilateral labyrinthectomy on rat postural muscle properties: the soleus.
abstract: The aim of our study was to determine whether the suppression of the vestibular inputs could have effects on the soleus muscle properties similar to the modifications observed after an episode of microgravity. The inner ear lesion was performed by surgical labyrinthectomy. Twenty-nine male Wistar rats were used for this study and were divided into three experimental groups: control (CONT, n=7), unilateral labyrinthectomized (UL, n=14) and bilateral labyrinthectomized (BL, n=8). Mechanical, histochemical and electrophoretic parameters were determined 17 days after the operation. Furthermore, electromyographic (EMG) activity of the soleus muscle was examined at 1 h, 1 day and 17 days. Our results showed that UL and BL groups did not present any sign of muscle atrophy when compared to CONT group. However, the contractile and phenotypical characteristics of UL and BL soleus muscles revealed that the muscle evolved from slow toward a slower type. This transition was correlated with a more tonic EMG activity pattern. To conclude, our data demonstrated that soleus muscle transformations observed after microgravity (muscle atrophy, slow-to-fast transition, phasic EMG activity) were not directly the consequence of a vestibular silence.
authors.affiliation: Laboratoire de Plasticité Neuromusculaire, Université des Sciences et Technologies de Lille 1, F-59655 Villeneuve d'Ascq cedex, France. neuromus@univ-lille1.fr
authors.forename: Mounir
authors.initials: M
authors.lastname: Kasri
authors.forename: Florence
authors.initials: F
authors.lastname: Picquet
authors.forename: Maurice
authors.initials: M
authors.lastname: Falempin
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D007758:Ear, Inner / Q000502:physiology* / Q000601:surgery; D004567:Electrodes, Implanted; D004576:Electromyography; D004591:Electrophoresis, Polyacrylamide Gel; D007839:Functional Laterality / Q000502:physiology*; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000166:cytology* / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000032:analysis / Q000378:metabolism; D013506:Otologic Surgical Procedures; D011187:Posture / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013314:Stress, Mechanical
chemical_list: D018995:Myosin Heavy Chains