Relationships of Serum Leptin Levels with Biochemical Markers of Bone Turnover and with Growth Factors in Normal Weight and Overweight Children

Abstract

Objective: To examine the hypothesis of an influence of leptin on growth factors and on biochemical markers of bone turnover of prepubertal overweight children. Design and Methods: 395 prepubertal children, 6–13 years of age, were selected and the relationships between circulating serum levels of leptin and insulin-like growth factor I (IGF-I), insulin growth factor binding protein-3 (IGFBP-3) and some biochemical markers of bone turnover (osteocalcin, OC; carboxyterminal propeptide of type I procollagen, PICP, and carboxyterminal propeptide of type I collagen, ICTP) were analyzed. The subjects were subdivided into normal weight (NW, n = 163) and weight excess (WE, n = 232) subjects. Results and Conclusions: Significant differences between the two groups were found for leptin (p < 0.01), IGF-I (p < 0.01) and IGFBP-3 (p < 0.01), with higher values in WEs, and for OC (p < 0.01) with higher values in NWs. A significant reduction of leptin (p < 0.01) and IGFBP-3 (p < 0.01) serum values and an increase of those of OC (p < 0.01) and PICP (p < 0.05), but not of ICTP, were registered in 103 WEs who showed a drop in weight excess during a weight-excess reduction program. No variations were observed in 26 non-responsive subjects. In a multivariate analysis in which leptin, corrected by BMI and sex, was the independent variable, a significant negative correlation was found with PICP (β = –0.235, p < 0.01), IGF-I (β = –0.180, p < 0.01) and height velocity (β = –0.155, p < 0.01). There was no correlation with OC, ICTP and IGFBP-3. The results demonstrate that nutritional status and leptin levels are involved in the regulation of growth factors and biochemical markers of bone formation.

A new link between skeleton, obesity and insulin resistance: relationships between osteocalcin, leptin and insulin resistance in obese children before and after weight loss

“…Furthermore, studies in children showed that normal weight children had significantly higher circulating osteocalcin levels than overweight children. 5,32 Osteocalcin levels have been reported to increase in overweight adults after weight loss. 8,9,30 The only existing human study with no increase in osteocalcin after weight loss was based on a high protein, high calcium diet, which probably explains this difference.…”

“…Mice lacking the gene that encodes osteocalcin (osteocalcin À/À) have an abnormal amount of visceral fat and exhibit glucose intolerance, IR and impaired insulin secretion compared with wild-type mice. 2 In humans, lower circulating osteocalcin levels were found in overweight 4,5 and diabetic subjects 6,7 compared with normal weight individuals. Moreover, osteocalcin concentrations increase after weight loss in overweight individuals 8,9 and after improvement in glycemic control in subjects with type 2 diabetes.…”

Whole-Body Vibration Mimics the Metabolic Effects of Exercise in Male Leptin Receptor–Deficient Mice

“…Although a significant body of literature suggests that obesity reduces risk of osteopenia and osteoporosis (1, 2), there are also numerous recent reports that obesity and its comorbidities reduce bone formation (3–6). Obesity is accompanied by ectopic lipid deposition in multiple tissues, including the skeleton, where infiltration of adipocytes into the bone marrow niche may negatively impact bone formation (7, 8).…”

The interrelationships between adipose tissue, leptin and selected bone metabolism markers in girls

“…Wpływ leptyny na wskaź-niki biochemiczne przemian kostnych u dzieci badany był również przez Bini i wsp. [9] u dzieci z nadwagą w wieku 6-13 lat. Dzieci otyłe miały wyższe stężenia leptyny, IGF-1, IGFBP-3 i niż-sze stężenie osteokalcyny niż dzieci o prawidłowej masie ciała.…”