title: Effect of tamoxifen on fatty degeneration and atrophy of rotator cuff muscles in chronic rotator cuff tear: An animal model study.
abstract: Fatty degeneration of the rotator cuff muscles is an irreversible change resulting from chronic rotator cuff tear and is associated with poor clinical outcomes following rotator cuff repair. We evaluated the effect of Tamoxifen, a competitive estrogen receptor inhibitor, on fatty degeneration using a mouse model for chronic rotator cuff tear. Sixteen adult mice were divided into two diet groups (Tamoxifen vs. Regular) and subjected to surgical creation of a large rotator cuff tear and suprascapular nerve transection in their left shoulder with the right shoulder serving as a control. The rotator cuff muscles were harvested at 16 weeks and subjected to histology and RT-PCR for adipogenic and myogenic markers. Histology showed substantially decreased atrophy and endomysial inflammation in Tamoxifen group, but no significant differences in the amount of intramuscular adipocytes and lipid droplets compared to the Regular group. With RT-PCR, the operated shoulders showed significant upregulation of myogenin and PPAR-γ, and downregulation of myostatin compared to the nonsurgical shoulder. No significant differences of gene expression were found between the two diet groups. Our study demonstrated that tamoxifen diet leads to decreased muscle atrophy and inflammatory changes following chronic rotator cuff tear, but has no apparent effect on adipogenesis.
authors.affiliation: Department of Orthopaedics and Rehabilitation, Penn State College of Medicine, Hershey, Pennsylvania.
authors.forename: Edward
authors.initials: E
authors.lastname: Cho
authors.affiliation: Department of Orthopaedics and Rehabilitation, Penn State College of Medicine, Hershey, Pennsylvania.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania.
authors.forename: Anne
authors.initials: A
authors.lastname: Pruznak
authors.affiliation: Department of Orthopaedics and Rehabilitation, Penn State College of Medicine, Hershey, Pennsylvania.
authors.forename: H Mike
authors.initials: HM
authors.lastname: Kim
mesh_terms: D017667:Adipocytes / Q000166:cytology; D050156:Adipogenesis / Q000187:drug effects*; D000818:Animals; D001823:Body Composition; D004195:Disease Models, Animal; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D007249:Inflammation; D008055:Lipids / Q000737:chemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009133:Muscular Atrophy / Q000188:drug therapy / Q000473:pathology*; D018008:Myogenin / Q000378:metabolism; D055435:Myostatin / Q000378:metabolism; D047495:PPAR gamma / Q000378:metabolism; D011960:Receptors, Estrogen / Q000037:antagonists & inhibitors; D017006:Rotator Cuff / Q000187:drug effects / Q000473:pathology*; D000070636:Rotator Cuff Injuries; D020845:Selective Estrogen Receptor Modulators / Q000627:therapeutic use; D013629:Tamoxifen / Q000627:therapeutic use*; D013710:Tendons / Q000473:pathology
chemical_list: D008055:Lipids; D018008:Myogenin; D055435:Myostatin; D047495:PPAR gamma; D011960:Receptors, Estrogen; D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen
keywords: atrophy; fatty degeneration; mouse model; rotator cuff tear; tamoxifen