title: Age-related changes in rat genioglossus, geniohyoid and masseter muscles.
abstract: OBJECTIVE
  The aim of this study was to elucidate age-related changes from adult to middle age in the contractile properties of the masseter, genioglossus and geniohyoid muscles of the rat.
  
  
  METHODS
  We analysed the expressions of myosin heavy chain (MyHC) mRNAs and proteins as indicators of the contractile properties in these muscles obtained from rats at 6, 12, 18 and 24 months of age using real-time PCR and SDS-PAGE.
  
  
  RESULTS
  We found no marked age-related changes in the expressions of MyHC mRNAs and proteins in rat masseter and geniohyoid muscles, suggesting that the biological ageing process does not affect contractile properties in these muscles. However, we found a decrease in the expression of MyHC IIb mRNA with ageing in the rat genioglossus muscle, suggesting that biological ageing process induces at least some fast-to-slow myofibre phenotype transition.
  
  
  CONCLUSIONS
  The biological ageing process from adult to middle age appears to differentially affect different types of craniofacial muscles.
authors.affiliation: Department of Geriatric Dentistry, School of Dental Medicine, Tsurumi University, Yokohama, Japan.
authors.forename: Syuhei
authors.initials: S
authors.lastname: Kaneko
authors.forename: Ryo-hei
authors.initials: RH
authors.lastname: Iida
authors.forename: Takeo
authors.initials: T
authors.lastname: Suga
authors.forename: Mitsuhiko
authors.initials: M
authors.lastname: Morito
authors.forename: Akira
authors.initials: A
authors.lastname: Yamane
mesh_terms: D000375:Aging / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D001835:Body Weight; D008297:Male; D008406:Masseter Muscle / Q000737:chemistry / Q000473:pathology*; D009119:Muscle Contraction; D018656:Muscle Fibers, Fast-Twitch / Q000737:chemistry / Q000473:pathology; D018657:Muscle Fibers, Slow-Twitch / Q000737:chemistry / Q000473:pathology; D018995:Myosin Heavy Chains / Q000032:analysis; D024462:Myosin Type II / Q000032:analysis; D009334:Neck Muscles / Q000737:chemistry / Q000473:pathology*; D010641:Phenotype; D051381:Rats; D017208:Rats, Wistar; D014059:Tongue / Q000737:chemistry / Q000473:pathology*
chemical_list: D024462:Myosin Type II; D018995:Myosin Heavy Chains