Circulating concentrations of soluble leptin receptor: influence of menstrual cycle and diet therapy (original) (raw)
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Leptin and Soluble Leptin Receptor Levels in Obese and Weight-Losing Individuals
The Journal of Clinical Endocrinology & Metabolism, 2002
To investigate soluble leptin receptor (sLR) in plasma, specific anti-sLR monoclonal antibodies were developed. Western blot analysis and size exclusion fractionation demonstrated sLR in plasma with a molecular mass of approximately 180,000. Next to this, the presence of sLR-leptin complexes in plasma was confirmed. Using the developed monoclonal antibodies, a specific sLR ELISA was developed, which measured in plasma both free and sLR bound to leptin. sLR appeared to inhibit leptin concentrations measured in four different leptin assays indicating that these assays primarily measure free leptin and underestimate the total leptin present in plasma. Furthermore, plasma levels of sLR and leptin were measured in 21 lean individuals and in 30 morbidly obese subjects before and 3, 6, and 12 months after gastric restrictive surgery. Preoperatively, leptin concentrations significantly correlated with body mass index (r ؍ 0.796, P < 0.001). In contrast, sLR significantly inversely correlated with body mass index (r ؍ ؊0.294, P < 0.05). In lean subjects, the molar ratio of free leptin to sLR was 1:1, whereas in morbidly obese subjects a ratio of 25:1 was found. After weight loss due to surgery, leptin levels rapidly decreased and sLR levels slowly increased to reach normal values at 12 months postoperatively. We conclude that sLR levels are significantly decreased, whereas leptin levels are significantly increased in morbidly obese subjects compared with lean individuals.
Effect of Variations in Body Mass Index on Serum Leptin Levels in
2016
Objective: To measure the serum leptin and insulin levels and assess that how body mass index and affects these levels in pre and post menopausal obese and non-obese women. Place and duration of study: It was a comparative study. Sampling was done from various Hospitals, organizations and residential areas. The experimental work was carried out at the department of Biochemistry & Molecular Biology and Center for Research in Experimental and Applied Medicine-1 (CREAM-1), NUST, Rawalpindi, Pakistan and was spread on duration of 18 months. Methodology: The samples for the study were obtained from healthy eighty subjects & divided into premenopausal and postmenopausal groups of 40 each which were further sub-divided into obese and non obese based on the body mass index (cutoff BMI value = 25 kg/m). Fasting blood sugar, triglycerides, serum Insulin and serum leptin were measured along with BMI and HOMA IR. Data was analyzed for frequencies, percentages, means and standard deviation ( ± S...
The adipocyte-derived hormones leptin [which circulates in a free form and bound to a soluble leptin receptor (sOB-R)], adiponectin, and resistin play a key role in regulating energy homeostasis and metabolism. We assessed the association between body composition, total energy, and macronutrient intake and serum leptin, sOB-R, free leptin index, adiponectin, and resistin concentrations in 61 female and 53 male consecutively enrolled healthy Greek students. In this crosssectional study, total energy and macronutrient intake were determined using 3-d food records. Body composition was assessed by bioelectrical impedance analysis; fasting blood samples were taken for the measurement of total leptin, sOB-R, adiponectin, and resistin; and the ratio leptin/sOB-R was used as an index of free leptin. Serum sOB-R concentrations were lower in the female subjects compared with the males (27.24 ؎ 29.06 vs. 50.14 ؎ 39.74 ng/ml, P < 0.001), whereas leptin, adiponectin, and resistin concentrations were significantly higher in females (leptin: 9.93 ؎ 6.01 vs. 3.27 ؎ 2.54 ng/ml, P < 0.001; adiponectin: 11.40 ؎ 6.73 g/ml vs. 4.90 ؎ 2.79 g/ml; P < 0.001; resistin: 16.86 ؎ 5.39 ng/ml in females vs. 14.00 ؎ 7.16 ng/ml in males, P < 0.02). Simple regression analysis showed that, in both genders, leptin, free leptin index, adiponectin, and resistin correlated positively with body fat mass and negatively with waist to hip ratio. sOB-R correlated negatively with body fat mass and positively with waist to hip ratio. Multiple regression analysis models controlling for gender, body fat, and total energy intake demonstrated that sOB-R is positively associated with energy intake from carbohydrates and negatively with energy intake from dietary fat, whereas free leptin index is negatively associated with energy intake from carbohydrates and positively with energy intake from dietary fat. No statistically significant correlations were observed between serum adiponectin or resistin concentrations and total energy or macronutrient intake. Thus, total energy intake and macronutrient composition of the diet are associated with sOB-R and free leptin index but do not play a role of comparable significance in predicting adiponectin and resistin concentrations in healthy young subjects. (J Clin Endocrinol Metab 88: 1730 -1736, 2003)
Maturitas, 2008
Objective: In obese postmenopausal women with normal glucose metabolism (NGT) and impaired glucose tolerance (IGT) we assessed serum leptin, adiponectin, resistin, soluble leptin receptor (sOB-R) during oral glucose tolerance test (OGTT) in order to investigate their response to acute changes in glucose and insulin in the abnormal glucose metabolism, as it is early detected by IGT. Methods: Thirty in total, overweight/obese postmenopausal women, were included in the study: 15with NGT and 15 with IGT as it was diagnosed by OGTT. Serum glucose and insulin levels were measured at 30 min intervals, leptin, sOB-R, adiponectin and resistin at 60 min intervals during the 120 min OGTT. Results: In fasting state, leptin, adiponectin, resistin and sOB-R levels did not differ between the two groups. In women with NGT, leptin was positively correlated with BMI, insulin and HOMA, and negatively correlated with QUICKI and with sOB-R; adiponectin was negatively correlated with insulin and HOMA and positively correlated with QUICKI. In women with IGT, resistin was positively correlated with BMI and waist circumference. In both groups, sOB-R was negatively correlated with insulin. During OGTT, in both groups, leptin concentration increased significantly and fasting glucose predicts significantly serum leptin change; there was no change in adiponectin, resistin and sOB-R concentrations. Conclusion: In overweight/obese postmenopausal women fat distribution does not affect leptin and adiponectin production. Abnormal glucose metabolism is not accompanied by disturbance in adipokines production. Leptin secretion is acutely regulated by glucose levels in insulin presence.
Diabetes, 2000
Leptin resistance and obesity have been related to mutations of the leptin receptor gene in rodents and, recently, in a consanguineous family. The latter mutation results in a receptor lacking transmembrane and intracellular domains. Homozygous and heterozygous individuals with this mutation had serum leptin levels higher than expected, given their BMIs: 600, 670, and 526 ng/ml and 145, 362, 294, 240, and 212 ng/ml, respectively. Their serum leptin was fractionated by gel filtration: >80% was present as a high-molecular size complex vs. 7.5% in the nonmutated sister. Western blot analysis showed a band at 146 kDa reacting specifically with an antibody directed against the leptin receptor ectodomain. In 10 obese control subjects, as in the mutated patients, free leptin levels correlated with BMI (r = 0.70, P = 0.0011) and reflected fat mass, regardless of leptin receptor functioning. In the patients, bound leptin levels correlated with BMI (r = 0.99, P = 0.0002) and were related to the number of mutated alleles. These data demonstrate that the truncated receptor is secreted into blood and binds the majority of serum leptin, markedly increasing bound and total leptin. Free serum leptin was similarly correlated with BMI in the mutated and nonmutated obese individuals, providing evidence that the relationship between BMI and circulating free leptin is preserved in this family. This finding suggests that the leptin receptor itself may not be specifically involved in the control of leptin secretion, and it supports the concept of relative resistance to leptin in common obesity.
Gender Differences in Serum Leptin Levels in Humans
Biochemical and Molecular Medicine, 1996
organ that may play a significant role in regulating Leptin, the product of the ob gene, is an adipose satiety and thermogenesis (2-13). We (4) and others tissue-derived hormone that appears to regulate both (8,11,12) have reported that human adipose tissue prosatiety and thermogenesis. In the present report, we duces a nonmutated form of the ob gene. In addition, have reexamined the relationship between circulatwe (3) have recently reported that serum ob protein ing leptin concentration and body fat in humans us-(leptin) concentration is closely associated with body ing a more valid measure of adiposity (hydrodensitometry) and have extended these observations to ex-fat as assessed by either body mass index (BMI) or amine the influence of regional body fat distribution bioelectrical impedance. However, neither of these proand cardiorespiratory fitness. Fasting serum leptin cedures are considered to be highly accurate means concentration was 6.9 { 0.3 ngrml 01 in males (N Å 333) of assessing adiposity (14,15). Thus, we believe it is and 15.2 { 1.3 ngrml 01 in females (N Å 63). Interestimperative to confirm our previous observations using ingly, total fat mass did not differ between groups a more valid measure of body fat (hydrodensitometry). (males 20.5 { 0.5 kg; females 20.4 { 1.5 kg), suggesting
Obesity Research, 1998
This investigation was designed to determine the relationship of leptin concentration to gender, sex hormones, menopause, age, diabetes, and fat mass in African Americans. Participants included 101 African Americans, 38 men (mean age, 34.2 i 7.4 years), 29 agematched premenopausal women (mean age, 32.6 * 3.7 years), and 36 postmenopausal women (mean age, 57.8 i 5.9 years). The women were not taking exogenous sex hormones, and 12 subjects were diabetic. Percent body fat was calculated with the Siri formula, fat mass (FM) was calculated as weight x percent body fat, and Fatfree mass (FFM) was calculated as weight minus FM. Fasting plasma was assayed for leptin, estradiol, free testosterone, glucose, and insulin concentrations. The nondiabetics had an oral glucose tolerance test (OGTT). The diabetics compared with the non-diabetics had a higher central fat index @=OM) but otherwise were similar to nondiabetics in all parameters measured. Body mass index, percent body fat, and FM were greater in women than men @<0.001). Leptin concentrations in men, premenopausal, and postmenopausal women were: 7.51 i 8.5, 33.9 i 17.3, 31.4 f 22.3 ng/mL. Leptin/FM x 100 in the three groups were: 28.9 f 16.1, 98.65 f 44.9, 77.1 f 44.5 ng/mL/kg. The gender difference in leptin concentration and leptin/FM was significant (p<O.Ool),
EFFECT OF BODY MASS INDEX ON SERUM LEPTIN LEVELS
Background: Leptin is product of ob gene, an adipose tissue derived hormone that plays a key role in the regulation of body fat mass by regulating appetite and metabolism while balancing energy intake and energy expenditure. The objective of the study was to evaluate possible association between serum leptin levels and Body Mass Index (BMI) of gender in adult age group. Methods: Two-hundredseventy subjects aged 20-50 years were randomly selected from general population of Abbottabad. The subjects were grouped on the basis on BMI (89 normal, 92 overweight, and 89 obese). After complete evaluation, demographic data was recorded and BMI. Non-fasting venous blood samples were drawn to measure serum leptin and serum glucose levels. The data were analysed using SPSS-15 calculating mean, percentage, independent t-test and chi-square test. Correlation and regression curve analysis were obtained, and p and r values were calculated. Results: Serum leptin levels and differences between genders were significant in all body mass indices. For normal BMI group the mean values for leptin were 2.6±1.5 ηg/ml in men, and 17.3±10.2 ηg/ml for women. For Group-2 mean leptin levels in men were 9.9±6.8 ηg/ml and in women were 34.8±13.6 ηg/ml. For Group-3 BMI comprising obese subjects mean values for men were 21.3±14.2 ηg/ml and for women were 48.21±21.2 ηg/ml (p<0.001). Conclusion: A progressive increase in serum leptin concentration was observed with an increase in BMI. Significant difference between leptin concentrations in either gender was found in normal, overweight and obese subjects.
Serum leptin activity in obese and lean patients
Regulatory Peptides, 2003
Blood levels of the satiety hormone leptin are directly correlated to fat stores in obese and lean people. Therefore, leptin resistance is the logical explanation for the phenomenon of common obesity. However, the important question of whether or not the intrinsic leptin activity could differ between obese and lean people has not been examined before. In the present study, serum leptin activity was measured by an in vitro assay of leptin signaling in a modified culture of HEK-293 cells. The system is based on activation of a luciferase reporter gene through a leptin receptor-dependent activation of the signal transducer and activator of transcription (STAT3). Serum samples from 20 obese and 20 non-obese individuals with leptin levels ranging from 3 to 75 ng/ml, as determined by radioimmunoassay (RIA), were used. A high correlation was observed for each serum sample between leptin RIA values and leptin activity in the bioassay. The results indicate that obesity in the 20 obese patients among the 40 individuals examined cannot be accounted for by alterations in leptin activity in our assay. The assay system provides a tool to screen for possible rare cases exhibiting alteration in leptin activity either due to a change in leptin itself or through interaction with other serum factors. D
Leptin resistance and diet-induced obesity: central and peripheral actions of leptin
Metabolism: clinical and experimental, 2015
Obesity is a chronic disease that represents one of the most serious global health burdens associated to an excess of body fat resulting from an imbalance between energy intake and expenditure, which is regulated by environmental and genetic interactions. The adipose-derived hormone leptin acts via a specific receptor in the brain to regulate energy balance and body weight, although this protein can also elicit a myriad of actions in peripheral tissues. Obese individuals, rather than be leptin deficient, have in most cases, high levels of circulating leptin. The failure of these high levels to control body weight suggests the presence of a resistance process to the hormone that could be partly responsible of disturbances on body weight regulation. Furthermore, leptin resistance can impair physiological peripheral functions of leptin such as lipid and carbohydrate metabolism and nutrient intestinal utilization. The present document summarizes those findings regarding leptin resistanc...