title: Stress deprivation from the patellar tendon induces apoptosis of fibroblasts in vivo with activation of mitogen-activated protein kinases.
abstract: The effect of stress deprivation on the tendon tissue has been an important focus in the field of biomechanics. However, less is known about the in vivo effect of stress deprivation on fibroblast apoptosis as of yet. This study was conducted to test a hypothesis that complete stress deprivation of the patellar tendon induces fibroblast apoptosis in vivo with activation of Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38) within 24 h after treatment. A total of 35 mature rabbits were divided into stress-shielded (n=15), sham-operated (n=15), and control (n=5) groups. To completely shield the patellar tendon from stress, we used an established surgical method. Animals were sacrificed at 24 h, and 2, 4, 7, and 14 days after the treatment. Tendon specimens underwent TUNEL assay and immunohistological examinations of active caspase-3, JNK, and p38. Both the number and the ratio of TUNEL-positive and caspase-3-positive cells were significantly greater (p<0.0001) in the stress-shielded group than in the sham group at 24 h, 2, 4, and 7 days. Concerning JNK and p38, both the number and the ratio were significantly greater (p<0.0001) in the stress-shielded group than in the sham group at 24 h, 2, and 4 days. This study demonstrated that complete stress deprivation induces fibroblast apoptosis in vivo with activation of JNK and p38 within 24 h. This fact suggested that the fibroblast apoptosis caused by stress deprivation is induced via the mitogen-activated protein kinase signaling pathway.
authors: Department of Sports Medicine and Joint Surgery, Hokkaido University Graduate School of Medicine, Kita 15 Nishi 7, Kita-ku, Sapporo 060-8638, Japan.
authors: Hideyuki
authors: H
authors: Kawabata
authors: Taro
authors: T
authors: Katsura
authors: Eiji
authors: E
authors: Kondo
authors: Nobuto
authors: N
authors: Kitamura
authors: Shin
authors: S
authors: Miyatake
authors: Yoshie
authors: Y
authors: Tanabe
authors: Takao
authors: T
authors: Setoguchi
authors: Setsuro
authors: S
authors: Komiya
authors: Kazunori
authors: K
authors: Yasuda
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002478:Cells, Cultured; D004789:Enzyme Activation; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology*; D019417:Hindlimb Suspension; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D017847:Patellar Ligament / Q000166:cytology* / Q000502:physiology*; D011817:Rabbits; D013314:Stress, Mechanical
chemical_list: D020928:Mitogen-Activated Protein Kinases