Serum leptin levels, bone mineral density and osteoblast alkaline phosphatase activity in elderly men and women.
Although primarily secreted by adipose cells, leptin, a polypeptide hormone that influences body weight, satiety and lipid metabolism, and its receptor are also expressed in human osteoblasts. Leptin plays a role in the central, hypothalamic modulation of bone formation, as well as locally within the skeleton by enhancing differentiation of bone marrow stroma into osteoblasts and inhibiting its differentiation into osteoclasts and adipocytes. The purpose of this investigation was to compare serum leptin values in 100 postmenopausal women (age 62-97) and 31 men (age 72-92) to bone mineral density (BMD) measurements made by dual X-ray absorptiometry and additionally to biochemical markers of bone resorption and formation, including crosslinked collagen N-telopeptides (NTx), aminoterminal extension procollagen propeptides (PINP) and bone-specific alkaline phosphatase (bAP). The circulating level of leptin directly correlated with body mass index (BMI) (r=0.61-0.78, P<0.001) and was modestly, but significantly and positively associated with bAP activity (r=0.24-0.33, P<0.01) in the sera of men and women after adjustment for BMD, age and BMI. The association of circulating leptin levels with bAP, a specific marker of osteoblast activity suggests that leptin levels influence osteoblast activity in vivo in elderly women and men.
Scariano
John K
JK
Medical Laboratory Sciences, Department of Pathology, HSSB Room 220, University of New Mexico School of Medicine, Albuquerque, NM 87131-5651, USA. jscariano@salud.unm.edu
Garry
Philip J
PJ
Montoya
George D
GD
Chandani
Ali K
AK
Wilson
Janice M
JM
Baumgartner
Richard N
RN
D015502:Absorptiometry, Photon; D000368:Aged / Q000502:physiology*; D000369:Aged, 80 and over; D000469:Alkaline Phosphatase / Q000378:metabolism*; D015415:Biomarkers; D015992:Body Mass Index; D015519:Bone Density / Q000502:physiology*; D001842:Bone and Bones / Q000378:metabolism; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D020738:Leptin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010006:Osteoblasts / Q000201:enzymology*; D011347:Procollagen / Q000378:metabolism; D012727:Sex Characteristics; D013131:Spine / Q000473:pathology
D015415:Biomarkers; D020738:Leptin; D011347:Procollagen; D000469:Alkaline Phosphatase