Quantitative Histology and MGF Gene Expression in Rats Following SSC Exercise In Vivo

Details

• Personal Author:
  Baker BA ; Cutlip, Robert G. ; Geronilla KB ; Kashon ML ; Mercer RR ; Miller, G. Roger ; Rao KMK
• Description:
  We investigated the effects of muscle length during stretch-shortening cycles (SSC) in vivo on changes in MGF gene expression and quantitative morphometry in rat skeletal muscle. Dorsiflexor muscles of male Sprague-Dawley rats were exposed to seven sets of 10 SSC at 500 degrees .s(-1). Animals were randomly assigned to a long muscle length injury group (L-inj), short muscle length injury group (S-inj), or isometric group (Iso), with recoveries examined at 6 or 48 h post-injury for each group. Following exposure, animals were euthanized, and the tissue was prepared for either histology (quantitative morphometry) or RNA isolation, followed by quantitative real-time reverse transcriptase polymerase chain reaction. mRNA levels were measured for mechano-growth factor (MGF), while 18S ribosomal RNA served as the internal reference sample. Stereological measures indicative of edema and myofiber degeneration were significantly increased in the L-inj SSC group at 48 h when compared with the S-inj or Iso group. MGF mRNA was increased transiently at 6 h in the isometric group. In contrast, MGF mRNA was increased at 48 h in the S-inj, but was not increased at either time point in the L-inj group. These data strongly indicate that exposure to SSC at longer muscle lengths result in greater morphometric indices of inflammation and degeneration than SSC conducted at a shorter muscle lengths or isometric contractions, at the same time that the adaptation to SSC was prolonged and, apparently, not resolved in the L-inj group that was manifested by the lack of up-regulation in MGF mRNA. [Description provided by NIOSH]
• Subjects:
  Animals Environmental Monitoring Histology Laboratories Musculoskeletal System Occupational Health Safety
• Keywords:
  Animal-studies Exposure-assessment Exposure-levels In-vivo-studies Laboratory-animals Muscle-tissue Muscles Skeletal-system
• ISSN:
  0195-9131
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 3 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  463-471
• Volume:
  38
• Issue:
  3
• NIOSHTIC Number:
  nn:20029864
• Citation:
  Med Sci Sports Exerc 2006 Mar; 38(3):463-471
• Federal Fiscal Year:
  2006
• NORA Priority Area:
  Disease and Injury: Musculoskeletal Disorders of the Upper Extremities
• Peer Reviewed:
  True
• Source Full Name:
  Medicine and Science in Sports and Exercise
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:40ea29dbde4709d413fc78ebf5d4916b31d7f5a7d4187f8182bce4f320c2424fd8d07665473c2e80af23a435faf0e6c62c138244ef44a006d8146a5aaa2046cc
• Download URL:
  https://stacks.cdc.gov/view/cdc/190766/cdc_190766_DS1.pdf
• File Type:
  [PDF - 452.02 KB ]