Leptin prevents the fall in plasma osteocalcin during starvation in male mice.
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.
Goldstone
A P
AP
Endocrine Unit, Imperial College School of Medicine, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK. tgoldstone@yahoo.com
Howard
J K
JK
Lord
G M
GM
Ghatei
M A
MA
Gardiner
J V
JV
Wang
Z L
ZL
Wang
R M
RM
Girgis
S I
SI
Bailey
C J
CJ
Bloom
S R
SR
D000818:Animals; D020738:Leptin / Q000235:genetics / Q000494:pharmacology* / Q000502:physiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009765:Obesity / Q000235:genetics; D015675:Osteocalcin / Q000097:blood*; D010907:Pituitary Hormones / Q000097:blood; D013217:Starvation
D020738:Leptin; D010907:Pituitary Hormones; D015675:Osteocalcin