title: Histochemical and ultrastructural changes of sternomastoid muscle in aged Wistar rats.
abstract: The aim of this study was to evaluate histochemically and ultrastructurally the sternomastoid muscle (SM) of adults and aged rats, employing histochemic (NADH-TR reaction) and transmission electron microscopic methods. It was used 20 rats, divided into two groups: adults (n=10), animals with 4 months of age, and aged group (n=10), animals with 24 months of age. Five animals from each group were anesthetized with an overdose of urethane (3g/kg i.p.), and the muscles dissected after the samples processing for histochemical reaction (NADH-TR). Three types of fibers were identified by their metabolic characteristics: fibers with high oxidative capacity (O), intermediate oxidative capacity (OG) and low oxidative capacity (G). For transmission electron microscopic method, the animals were anesthetized and perfused by modified Karnovsky solution and the tissues were postfixed in 1% osmium tetroxide solution, dehydrated and embedded in Spurr resin. It was performed ultra-thin sections for transmission electron microscopic analysis. The SM showed heterogeneity in their composition according to the fiber types, with significant difference (p<0.05) when comparing the fibers types between the superficial and deep regions and between the adult and aged groups. It was observe a decrease between the comparison of the total fibers density and GO fiber, and an increase of the O fiber in aged group. Ultrastructural characteristics of muscle cells in aged group showed typical morphological changes, characterizing muscular atrophy. We conclude based on physiological ageing process, changes in muscle fibers classification, and ultrastructuraly, morphological alterations on muscle cells, characterizing a muscular atrophy.
authors.affiliation: Department of Anatomy, Institute of Biomedical Sciences-ICB, University of São Paulo, Av. Prof. Lineu Prestes, 2415 Butantã, 05508-900 São Paulo, SP, Brazil.
authors.forename: Adriano Polican
authors.initials: AP
authors.lastname: Ciena
authors.forename: Sonia Regina Yokomizo
authors.initials: SR
authors.lastname: de Almeida
authors.forename: Paulo Henrique de Matos
authors.initials: PH
authors.lastname: Alves
authors.forename: Regina de Sousa
authors.initials: Rde S
authors.lastname: Bolina-Matos
authors.forename: Fernando José
authors.initials: FJ
authors.lastname: Dias
authors.forename: João Paulo Mardegan
authors.initials: JP
authors.lastname: Issa
authors.forename: Mamie Mizusaki
authors.initials: MM
authors.lastname: Iyomasa
authors.forename: Ii-sei
authors.initials: IS
authors.lastname: Watanabe
mesh_terms: D000375:Aging; D000818:Animals; D006651:Histocytochemistry; D046529:Microscopy, Electron, Transmission; D018485:Muscle Fibers, Skeletal / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000648:ultrastructure*; D051381:Rats; D017208:Rats, Wistar / Q000033:anatomy & histology* / Q000502:physiology*