Bone Abstracts

Epidemiological and experimental data indicates that cadmium creates a risk of bone damage even at low exposure. Our recent findings suggest that this heavy metal may affect bone via destroying the receptor activator of nuclear factor (NF)-κβ (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system balance that plays a key role in the regulation of bone metabolism. The aim of this study was to investigate whether low-level exposure to cadmium, corresponding to low lifetime environmental human exposure, disturbs the RANK/RANKL/OPG system balance and if polyphenolic compounds, known to possess beneficial impact on bone metabolism, may protect from these disorders. Soluble RANKL (sRANKL) and OPG were measured (rat-specific ELISA kits by Immundiagnostik AG) in the bone tissue at the distal femoral end (trabecular bone region) of the female Wistar rats administered as the only drinking fluid 0.1% water extract of polyphenols from Aronia melanocarpa berries or/and cadmium in diet at the concentration of 1 mg/kg for 3, 10, 17, and 24 months. The exposure to cadmium increased the bone tissue concentration of sRANKL and decreased the concentration of OPG resulting in an increase in the sRANKL:OPG ratio, indicating intensified osteoclastogenesis. The administration of polyphenolic compounds under the exposure to cadmium importantly (partially after 10 months, and totally after 17 and 24 months) protected from this metal-induced disorders in the RANK/RANKL/OPG system. The results indicate that low chronic exposure to cadmium results in an imbalance in the RANK/RANKL/OPG system in the bone tissue and that consumption of polyphenolic compounds under this metal exposure protects from disorders in bone metabolism via improving the RANK/RANKL/OPG system balance. The findings suggest that consumption of polyphenol-rich diet by subjects environmentally exposed to cadmium may be beneficial for the skeleton.

This study was financially supported by the grant (no. N N405 051140) from the National Science Centre (Poland).