Leptin: a possible link between food intake, energy expenditure, and reproductive function

Magni, Paolo; Motta, Marcella; Martini, L.

doi:10.1016/s0167-0115(00)00149-x

Cited by 79 publications

(43 citation statements)

References 44 publications

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“…To our knowledge, this is the first report on plasma FL and BL in prepubertal DS children, and, although the number of DS subjects is small because of methodological limitations, the results obtained may add new information on this topic. This study indicates that both BL and FL are present in the plasma of DS prepubertal children and that FL concentrations increase, relatively to BL, together with adiposity and become prevalent once obese levels are reached, like in obese adults (Sinha et al, 1996;Magni et al, 2000). The significance of FL and BL partitioning is not completely understood: at least in adults, BL correlates with resting energy expenditure, whereas FL reflects adiposity (Brabant et al, 2000).…”

Section: Discussionmentioning

confidence: 89%

“…FL and BL were studied in six (five males, one female; classified as normal weight, overweight, and obese (Cole et al, 2000)) out of 24 DS children and not in the whole group, since this procedure requires relatively high amounts of plasma, that were difficult to collect for every DS child. FL and BL were studied using a FPLC system (Amersham Biosciences Italia, Milan, Italy), followed by RIA for leptin (Magni et al, 2000) and are expressed as both percent of the sum of the peak areas, and absolute values (ng), calculated as follows: FL (or BL)(ng) ¼ total leptin (ng/dl)*%FL (or %BL)/ 100. Plasma TSH, FT 4 , and FT 3 concentrations were determined by immunometric assays.…”

Section: Methodsmentioning

confidence: 99%

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Free and bound leptin in prepubertal children with Down's syndrome and different degrees of adiposity

et al. 2004

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Objective: To evaluate plasma total, free (FL) and protein-bound (BL) leptin in children with Down's syndrome (DS) and different degrees of adiposity and its relationship with thyroid stimulating hormone (TSH), free thyroxine (FT 4 ), and free triiodothyronine (FT 3 ). Subjects: A total of 24 prepubertal clinically euthyroid DS children. Methods: Plasma leptin, TSH, FT 4 , and FT 3 concentrations were determined by immunometric/radioimmunologic assays. FL and BL were evaluated by fast protein liquid chromatography. Results: In DS children, leptin circulates in two fractions, corresponding to BL and FL. The amount of BL and FL is negatively and positively correlated to body mass index (BMI), respectively. Plasma leptin concentrations correlate with BMI, but not with TSH, FT 4 , and FT 3 . Conclusions: In prepubertal DS children, leptin circulates as both BL and FL, correlates with adiposity and its concentration appears independent of thyroid function. Sponsorship: MIUR, Università degli Studi di Milano, Banca Popolare di Milano Foundation.

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Section: Discussionmentioning

confidence: 89%

Section: Methodsmentioning

confidence: 99%

Free and bound leptin in prepubertal children with Down's syndrome and different degrees of adiposity

et al. 2004

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“…The reasons for the association between metabolic syndrome and hypogonadism are not completely clear. It has been suggested that insulin resistance, acting through signs mediated by the adipose tissue, including increased levels of leptin, would have a direct role in the regulation of gonadal function, thus decreasing the concentrations of testosterone (1,4,25,26). At the same time, pro-inflammatory cytokines, such as TNF alpha, IL-1 and IL-6, produced by visceral adipocytes, are also associated with insulin resistance (27,28).…”

Section: Discussionmentioning

confidence: 99%

Relationship between insulin and hypogonadism in men with metabolic syndrome

Caldas

Porto

Motta

et al. 2009

Arq Bras Endocrinol Metab

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Objective: To evaluate the incidence of hypogonadism in men with metabolic syndrome and its correlation with serum insulin levels. Methods: Observational, transversal study with 80 men with metabolic syndrome. The individuals were divided into two groups: Group 1: 56 patients (70%) with total testosterone ≥ 300 ng/dL (normal gonadal function); Group 2: 24 patients (30%) with total testosterone < 300 ng/dL (hypogonadic). Results: The subjects from Group 2 compared to Group 1 presented higher body mass index (BMI), waist and hip circumferences, insulin, homeostasis model assessment insulin resistance index (Homa-IR) and beta cell (Homa-β), and triglycerides, but lower SHBG and free testosterone values. Inverse correlations between insulin levels and total testosterone and SHBG, as well as between Homa-IR and total testosterone were observed. Conclusion: In this series of men with metabolic syndrome, hypogonadism was associated with insulin resistance and may be a marker of metabolic abnormalities. Arq Bras Endocrinol Metab. 2009;53(8):1005-11

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“…Another isoform, Ob-Re, is speculated to be a soluble form of the receptor, and may function as a plasma leptin binding protein (Chen et al, 1996). Magni et al (2000) have reported that the bound/free ratio of plasma leptin is altered in obese individuals with free leptin accounting for 70 -80% of circulating leptin, while in normal subjects only 10-15% of plasma leptin is unbound.…”

Section: Discussionmentioning

confidence: 99%

Plasma clearance and tissue distribution of radiolabeled leptin in the chicken

McMurtry

2004

Comparative Biochemistry and Physiology - Part A: Molecular &am

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Leptin is an adipose and liver tissue-derived secreted protein in chickens that has been implicated in the regulation of food intake and whole-body energy balance. In this study, the metabolic clearance and tissue uptake of leptin were examined in the chicken (Gallus gallus). Four-week-old broiler males were infused with 125 I-labeled mouse leptin. Chromatography of radiolabeled leptin in plasma produced two peaks, one at 16 kDa (free leptin) and a free iodine peak. No leptin binding protein in blood was detected. Leptin was cleared with a half-life estimate of 23 min. In order to investigate the tissue distribution and uptake of radiolabeled leptin, multiple tissues were removed from infused birds at 15 and 240 min post-infusion, and trichloroacetic acid (TCA)-precipitable radioactivity was determined. The amounts of radioactivity at 15 min post-infusion in the tissues in rank order were: kidney, testis, lung, spleen, heart, liver, small and large intestine, gizzard, pancreas, bursa, leg and breast muscle, adrenals, and brain. A slightly different pattern of distribution was observed at 240 min postinfusion. We conclude from these studies that unlike mammals, no circulating leptin binding protein is present in chickens. Leptin is metabolized and cleared very rapidly from blood by the kidney. Published by Elsevier Inc.

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Leptin: a possible link between food intake, energy expenditure, and reproductive function

Cited by 79 publications

References 44 publications

Free and bound leptin in prepubertal children with Down's syndrome and different degrees of adiposity

Free and bound leptin in prepubertal children with Down's syndrome and different degrees of adiposity

Relationship between insulin and hypogonadism in men with metabolic syndrome

Plasma clearance and tissue distribution of radiolabeled leptin in the chicken

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