Treadmill training prevents bone loss by inhibition of PPARγ expression but not promoting of Runx2 expression in ovariectomized rats

• Published in: European journal of applied physiology Vol. 111; no. 8; pp. 1759 - 1767
• Main Authors: Chen, Yongjie, Wang, Shouhui, Bu, Shumin, Wang, Yingjie, Duan, Yushuang, Yang, Shaofeng
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.08.2011; Springer
• Subjects: Adipocytes; adipogenesis; Animal subjects; Animals; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Blood; Bone Density - drug effects; Bone Density - genetics; Bone Density - physiology; Bone loss; Bone mineral density; Bone Resorption - genetics; Bone Resorption - metabolism; Bone Resorption - prevention & control; Bones; Cbfa-1 protein; Core Binding Factor Alpha 1 Subunit - genetics; Core Binding Factor Alpha 1 Subunit - metabolism; Differentiation; Down-Regulation - drug effects; Down-Regulation - genetics; Dual energy X-ray absorptiometry; Estrogen Replacement Therapy; Exercise physiology; Exercise Test; Female; Fundamental and applied biological sciences. Psychology; Human Physiology; Inhibition; Menopause; Occupational Medicine/Industrial Medicine; Original Article; Osteogenesis; osteogenic factor; Ovariectomy; Peroxisome proliferator-activated receptors; Peroxisomes; Physical Conditioning, Animal - physiology; Physical training; PPAR gamma - genetics; PPAR gamma - metabolism; Proteins; Rats; Rats, Sprague-Dawley; Running - physiology; Sports Medicine; Transcription factors; Treadmill ergometry; Triglycerides; Uterus; Vacuoles; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports; Western blotting; Women; Bone marrow adipogenesis; Osteoporosis; OVX rats; Treadmill training; Osteogenic factors; Human; Physical training; Ovariectomy; Rat; Diseases of the osteoarticular system; Rodentia; Vertebrata; Mammalia; Bone marrow; Inhibition; Osteopenia
• DOI: 10.1007/s00421-010-1820-0
• ISSN: 1439-6319; 1439-6327

Exercise training has been reported to prevent bone loss in ovariectomized (OVX) rats and postmenopausal women. We hypothesized that treadmill training inhibited adipogenesis and enhanced osteogenesis through the regulation of adipocyte differentiation factor peroxisome proliferators-activated receptor gamma (PPARγ) and the osteogenic factor runt-related transcription factor 2 (Runx2) in a model of OVX-induced osteoporosis. To test this hypothesis, 3-month-old female Sprague–Dawley rats were divided randomly into the following groups: Sham, OVX, OVX exercised (EX), and OVX estrogen replacement (E 2 ). At the end of the experiment, the bone mineral density (BMD) was detected using DEXA and the morphology change of bone tissues and uterus was observed by HE staining. The protein expression for PPARγ and Runx2 were measured by immunohistochemistry and western blot and the bone triacylglycerol (TG) was extracted by methanol/chloroform. OVX dramatically increased the number of fat vacuoles, protein levels for PPARγ and Runx2 as well as the TG level in tibiae and lumbar vertebrate. In contrast, the serum level of E 2 , the lumbar vertebrate BMD as well as the proximal and distal femur BMD was significantly decreased in the OVX group. All changes induced by OVX were significantly reversed by exercise treatment except for the protein expression level of Runx2. Moreover, exercise treatment produced no estrogenic effects on uterus as evidenced by the uterus wet weight and histology. Treadmill training could prevent bone loss induced by OVX through the inhibition of adipocyte differentiation factor PPARγ rather than promoting osteogenic factor Runx2.