title: Myogenic gene expression at rest and after a bout of resistance exercise in young (18-30 yr) and old (80-89 yr) women.
abstract: The purpose of this study was to investigate mRNA expression of several key skeletal muscle myogenic controllers; myogenic differentiation factor (MyoD), muscle regulatory factor 4 (MRF4), myogenic factor 5 (Myf5), myogenin, myostatin, and myocyte enhancer factor 2 (MEF2) at rest and 4 h after a single bout of resistance exercise (RE) in young and old women. Eight young women (YW; 23 +/- 2 yr, 67 +/- 5 kg) and six old women (OW; 85 +/- 1 yr, 67 +/- 4 kg) performed 3 sets of 10 repetitions of bilateral knee extensions at 70% of one repetition maximum. Muscle biopsies were taken from the vastus lateralis before and 4 h after RE. Using real-time RT PCR, mRNA from the muscle samples was amplified and normalized to GAPDH. At rest, OW expressed higher (P < 0.05) levels of MyoD, MRF4, Myf5, myogenin, and myostatin compared with YW. In response to RE, there was a main time effect (P < 0.05) for the YW and OW combined in the upregulation of MyoD (2.0-fold) and MRF4 (1.4-fold) and in the downregulation of myostatin (2.2-fold). There was a trend (P = 0.08) for time x age interaction in MRF4. These data show that old women express higher myogenic mRNA levels at rest. The higher resting myogenic mRNA levels in old women may reflect an attempt to preserve muscle mass and function. When challenged with RE, old women appear to respond in a similar manner as young women.
authors.affiliation: Human Performance Laboratory Ball State University, Muncie, Indiana 47306, USA.
authors.forename: Ulrika
authors.initials: U
authors.lastname: Raue
authors.forename: Dustin
authors.initials: D
authors.lastname: Slivka
authors.forename: Bozena
authors.initials: B
authors.lastname: Jemiolo
authors.forename: Chris
authors.initials: C
authors.lastname: Hollon
authors.forename: Scott
authors.initials: S
authors.lastname: Trappe
mesh_terms: D000293:Adolescent; D000328:Adult; D000369:Aged, 80 and over; D000375:Aging / Q000235:genetics / Q000502:physiology*; D001707:Biopsy, Needle; D015444:Exercise / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D064326:MEF2 Transcription Factors; D018482:Muscle, Skeletal / Q000737:chemistry / Q000473:pathology / Q000502:physiology; D017570:MyoD Protein / Q000378:metabolism; D051787:Myogenic Regulatory Factor 5 / Q000378:metabolism; D018006:Myogenic Regulatory Factors / Q000378:metabolism*; D018008:Myogenin / Q000378:metabolism; D055435:Myostatin; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014891:Weight Lifting / Q000502:physiology*
chemical_list: D064326:MEF2 Transcription Factors; C525911:MSTN protein, human; D017570:MyoD Protein; D051787:Myogenic Regulatory Factor 5; D018006:Myogenic Regulatory Factors; D018008:Myogenin; D055435:Myostatin; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; C063403:myogenic factor 6