TY - JOUR
T1 - Age-related loss of muscle mass and bone strength in mice is associated with a decline in physical activity and serum leptin
AU - Hamrick, Mark W.
AU - Ding, Ke Hong
AU - Pennington, Catherine
AU - Chao, Yuh J.
AU - Wu, Yii Der
AU - Howard, Boyd
AU - Immel, David
AU - Borlongan, Cesario
AU - McNeil, Paul L.
AU - Bollag, Wendy B.
AU - Curl, Walton W.
AU - Yu, Jack
AU - Isales, Carlos M.
N1 - Funding Information:
Funding for this research was provided by the Offices of the Dean of the School of Medicine and the Vice-President for Research, and the Department of Orthopedics, at the Medical College of Georgia. Funding was also provided by grants from the National Institutes of Health (AR049717-01A2 to MWH and DK058680 to CMI).
PY - 2006/10
Y1 - 2006/10
N2 - The mechanisms underlying age-related loss of muscle and bone tissue are poorly understood but are thought to involve changes in sex hormone status, physical activity, and circulating levels of inflammatory cytokines. This study attempts to develop an animal model useful for evaluating these mechanisms in vivo. Male C57BL/6 mice were included for study at 3, 6, 12, 18, 24, and 29 months of age. Endocortical mineralizing surface, serum leptin, body weight, and percentage of body fat all increased between 6 and 12 months of age as activity level declined. Serum levels of the inflammatory marker IL-6 increased significantly after 12 months of age, following the observed increase in body weight and percent body fat. Hindlimb muscle mass declined significantly between 18 and 24 months of age, both absolutely and relative to total body mass, with a further decline (∼15%) between 24 and 29 months. Loss of muscle mass after 18 months of age was accompanied by a significant increase in bone resorption, as indicated by serum pyridinoline cross-links, and a significant decrease in fat mass, serum leptin, bone strength, bone mineral density, and vertical cage activity. No significant changes in serum testosterone with aging were detected in the mice, as levels were essentially constant between 6 and 29 months. Our data show that mice lose a significant amount of muscle and bone tissue with age, and this loss of musculoskeletal tissue is accompanied by a drop in serum leptin and preceded by a significant decrease in physical activity.
AB - The mechanisms underlying age-related loss of muscle and bone tissue are poorly understood but are thought to involve changes in sex hormone status, physical activity, and circulating levels of inflammatory cytokines. This study attempts to develop an animal model useful for evaluating these mechanisms in vivo. Male C57BL/6 mice were included for study at 3, 6, 12, 18, 24, and 29 months of age. Endocortical mineralizing surface, serum leptin, body weight, and percentage of body fat all increased between 6 and 12 months of age as activity level declined. Serum levels of the inflammatory marker IL-6 increased significantly after 12 months of age, following the observed increase in body weight and percent body fat. Hindlimb muscle mass declined significantly between 18 and 24 months of age, both absolutely and relative to total body mass, with a further decline (∼15%) between 24 and 29 months. Loss of muscle mass after 18 months of age was accompanied by a significant increase in bone resorption, as indicated by serum pyridinoline cross-links, and a significant decrease in fat mass, serum leptin, bone strength, bone mineral density, and vertical cage activity. No significant changes in serum testosterone with aging were detected in the mice, as levels were essentially constant between 6 and 29 months. Our data show that mice lose a significant amount of muscle and bone tissue with age, and this loss of musculoskeletal tissue is accompanied by a drop in serum leptin and preceded by a significant decrease in physical activity.
KW - Aging
KW - Bone loss
KW - Bone mineral density
KW - IL-6
KW - Sarcopenia
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U2 - 10.1016/j.bone.2006.04.011
DO - 10.1016/j.bone.2006.04.011
M3 - Article
C2 - 16750436
AN - SCOPUS:33748193352
SN - 8756-3282
VL - 39
SP - 845
EP - 853
JO - Bone
JF - Bone
IS - 4
ER -