Leptin prevents the fall in plasma osteocalcin during starvation in male mice |
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Authors: | Goldstone A P Howard J K Lord G M Ghatei M A Gardiner J V Wang Z L Wang R M Girgis S I Bailey C J Bloom S R |
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Institution: | Endocrine Unit, Imperial College School of Medicine, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK. tgoldstone@yahoo.com |
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Abstract: | Plasma osteocalcin, a marker of osteoblastic activity, is reduced in starvation, malnutrition, and anorexia nervosa, resulting in low bone turnover osteoporosis. Contradictory findings about the role of leptin as a link between nutritional status and bone physiology have been reported. We demonstrate that leptin-deficient ob/ob and leptin-resistant db/db male mice have increased plasma osteocalcin, and that in male ob/ob mice osteocalcin is not decreased by starvation, unlike control mice. Intraperitoneal leptin administration increased plasma osteocalcin in male ob/ob mice, and prevented its fall during 24h fasting and 5 days of food restriction in normal male mice. This effect may be mediated via actions on the hypothalamic-pituitary-testicular or -growth hormone axes, or a direct action on osteoblasts. These studies support the hypothesis that the fall in leptin during starvation and weight loss is responsible for the associated reduction in osteoblast activity, and suggest a role for leptin in regulating bone turnover. |
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Keywords: | Leptin Obesity Osteoporosis Osteoblast Osteocalcin Starvation Fasting Bone Anorexia nervosa Testosterone |
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