β-Criptoxanthin stimulates bone formation and inhibits bone resorption in tissue culture in vitro
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- Yamaguchi, M. & Uchiyama, S. Mol Cell Biochem (2004) 258: 137. doi:10.1023/B:MCBI.0000012848.50541.19
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The effect of β-cryptoxanthin, which is greatly present in fruits, has not been clarified so far on bone metabolism. The effect of β-cryptoxanthin on bone formation and bone resorption was investigated in tissue culture in vitro. Rat femoral-diaphyseal (cortical bone) and -metaphyseal (trabecular bone) tissues were cultured for 48 h in Dulbecco's modified Eagle's medium (high glucose, 4.5%) supplemented with antibiotics and bovine serum albumin. The experimental cultures contained 10–8–10–5 M β-cryptoxanthin. The presence of β-cryptoxanthin (10–6 or 10–5 M) caused a significant increase in calcium content, alkaline phosphatase activity and deoxyribonucleic acid (DNA) content in the diaphyseal and metaphyseal tissues. These increases were completely prevented in the presence of cycloheximide (10–6 M), an inhibitor of protein synthesis. β-Carotene (10–6 or 10–5 M) or xantine (10–6 or 10–5 M) had no effect on the diaphyseal and metaphyseal calcium contents. The bone-resorbing factors parathyroid hormone (1–34) (PTH; 10–7 M) or prostaglandin E2 (PGE2; 10–5 M) caused a significant decrease in calcium content in the diaphyseal and metaphyseal tissues. The decrease in bone calcium content induced by PTH or PGE2 was completely inhibited by β-cryptoxanthin (10–8−10–6 M). In addition, β-cryptoxanthin (10–8−10–6 M) completely inhibited the PTH (10–7 M)- or PGE2 (10–5 M)-induced increase in medium glucose consumption and lactic acid production by diaphyseal and metaphyseal tissues. The inhibitory effect of β-cryptoxanthin (10–7 M) on PTH (10–7 M)- or PGE2 (10–5 M)-stimulated decrease in the diaphyseal calcium content was significantly prevented in the presence of 10–3 M vanadate, an inhibitor of protein tyrosine phosphatase. Vanadate (10–3 M) did not have a significant effect on calcium content and lactic acid production in control bone tissues. The present study demonstrates that β-cryptoxanthin has a direct stimulatory effect on bone formation and an inhibitory effect on bone resorption in tissue culture in vitro.