Skip Navigation LinksHome > March 2006 - Volume 38 - Issue 3 > Quantitative Histology and MGF Gene Expression in Rats follo...
Medicine & Science in Sports & Exercise:
doi: 10.1249/01.mss.0000191419.67030.69
BASIC SCIENCES: Original Investigations

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

BAKER, BRENT A.; RAO, K. M. K.; MERCER, ROBERT R.; GERONILLA, KEN B.; KASHON, MIKE L.; MILLER, GERALD R.; CUTLIP, ROBERT G.

Collapse Box

Abstract

Purpose: 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.

Methods: Dorsiflexor muscles of male Sprague-Dawley rats were exposed to seven sets of 10 SSC at 500°·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.

Results: 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.

Conclusion: 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.

©2006The American College of Sports Medicine

Login

Article Tools

Share

Search for Similar Articles
You may search for similar articles that contain these same keywords or you may modify the keyword list to augment your search.

Connect With Us