MedWire News: Oxidative stress is associated with increased bone resorption and decreased bone mass in otherwise healthy postmenopausal women, Korean researchers report.
There is increasing evidence suggesting that reactive oxygen species may participate in the pathogenesis of diseases including atherosclerosis, neurodegenerative diseases, cancer, diabetes, and osteoporosis, note Moo Il Kang (The Catholic University of Korea, Seoul) and colleagues.
In the present study, Kang and team explored the association between oxidative stress, biochemical bone turnover markers, and bone mineral density (BMD) in 135 postmenopausal women aged 60-79 years. The women were non-smokers, and did not use medications known to influence bone metabolism or antioxidants.
Oxidative stress was evaluated in serum by measuring 8-hydroxy-2'-deoxyguanosine (8-OH-dG) levels.
The researchers found that 8-OH-dG levels correlated negatively with BMD at all sites examined (lumbar spine, total hip, femoral neck, and trochanter).
After adjusting for age, body mass index, years since menopause, and bone turnover markers, the risk for osteoporosis increased by 54% with each standard deviation increase in 8-OH-dG concentration.
The team also observed a positive association between 8-OH-dG and the bone resorption marker type I collagen C-telopeptide, which supports the view that oxidative stress is associated with increased bone resorption and low bone mass, say the researchers.
Further studies in cultures of primary human bone marrow cells revealed that hydrogen peroxide, which has strong oxidizing capacity, stimulated bone resorption in a concentration-dependent manner as demonstrated by increased pit area in the osteoclast activity assay substrate.
In addition, hydrogen peroxide increased cellular mRNA levels of macrophage colony-stimulating factor and Receptor Activator for Nuclear Factor κ B by 1.5- and -2-fold, respectively. Both of these proteins play an important role in osteoclastogenesis, note Kang et al.
"These results suggest that osteoporosis, at least in part, is a consequence of oxidative damage," the researchers conclude in the journal Calcified Tissue International.
They add that their findings have important implications for bone biology and treatment of osteoporosis, as "treatments that increase the oxidant defenses in bone could prevent bone loss-related diseases."
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