title: Effect of amplitude and frequency of cyclic tensile strain on the inhibition of MMP-1 mRNA expression in tendon cells: an in vitro study.
abstract: To determine the effect of cyclic strain amplitude and frequency on MMP-1 (interstitial collagenase) expression in tendon cells, rat tail tendons (RTT) were immobilized or cyclically displaced to various amplitudes (1, 3, or 6% strain at 0.017 Hz) or frequencies (1% strain at 0.017, 0.17, or 1.0 Hz) for 24 hr. Stress-deprivation for 24 hr resulted in a marked upregulation in MMP-1 expression. Cyclic tensile loading at 0.017 Hz was found to significantly inhibit, but not completely eliminate, MMP-1 expression at 1% strain. MMP-1 expression was completely eliminated at 3 and 6% strain. Increasing the frequency of application of the 1% strain to 0.17 or 1.0 Hz completely eliminated MMP-1 expression. Disruption of the actin cytoskeleton with cytochalasin D abolished all inhibitory effects of cyclic strain on MMP-1 expression. The results of our study demonstrate that MMP-1 expression in tendon cells can be modulated by varying amplitudes and frequencies of cyclic tensile strain, presumably through a cytoskeletally based mechanotransduction pathway.
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D000199:Actins / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D015638:Cytochalasin D / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000235:genetics*; D020781:Matrix Metalloproteinase 1 / Q000235:genetics*; D040542:Mechanotransduction, Cellular / Q000235:genetics; D010507:Periodicity; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical; D013710:Tendons / Q000166:cytology / Q000201:enzymology*; D013718:Tensile Strength / Q000502:physiology; D015854:Up-Regulation / Q000235:genetics; D016474:Weight-Bearing / Q000502:physiology
chemical_list: D000199:Actins; D012333:RNA, Messenger; D015638:Cytochalasin D; D020781:Matrix Metalloproteinase 1