title: Effects of microgravity on myogenic factor expressions during postnatal development of rat skeletal muscle.
abstract: To clarify the role of gravity in the postnatal development of skeletal muscle, we exposed neonatal rats at 7 days of age to microgravity. After 16 days of spaceflight, tibialis anterior, plantaris, medial gastrocnemius, and soleus muscles were removed from the hindlimb musculature and examined for the expression of MyoD-family transcription factors such as MyoD, myogenin, and MRF4. For this purpose, we established a unique semiquantitative method, based on RT-PCR, using specific primers tagged with infrared fluorescence. The relative expression of MyoD in the tibialis anterior and plantaris muscles and that of myogenin in the plantaris and soleus muscles were significantly reduced (P < 0.001) in the flight animals. In contrast, MRF4 expression was not changed in any muscle. These results suggest that MyoD and myogenin, but not MRF4, are sensitive to gravity-related stimuli in some skeletal muscles during postnatal development.
authors.affiliation: Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8502, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Inobe
authors.forename: Ikuko
authors.initials: I
authors.lastname: Inobe
authors.forename: Gregory R
authors.initials: GR
authors.lastname: Adams
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Baldwin
authors.forename: Shin'Ichi
authors.initials: S
authors.lastname: Takeda
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D015870:Gene Expression / Q000502:physiology; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics / Q000378:metabolism; D006614:Hindlimb; D018482:Muscle, Skeletal / Q000254:growth & development / Q000378:metabolism*; D017570:MyoD Protein / Q000235:genetics / Q000378:metabolism*; D018006:Myogenic Regulatory Factors / Q000235:genetics / Q000378:metabolism*; D018008:Myogenin / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013026:Space Flight; D014893:Weightlessness
chemical_list: D017570:MyoD Protein; C503803:Myog protein, rat; D018006:Myogenic Regulatory Factors; D018008:Myogenin; D012333:RNA, Messenger; C063403:myogenic factor 6; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases