The leptin era: new insight into the mechanisms of body weight homeostasis

The Effects of Reduction Mammaplasty on Serum Leptin Levels and Insulin Resistance

Background. The reduction mammaplasty has been a well-executed and known procedure in which considerable amount of fatty tissue is removed from the body. The authors aimed to show the effects of the reduction mammaplasty on serum leptin levels and insulin resistance. Methods. 42 obese female patients who had gigantomastia were operated on. We recorded patients' demographic and preoperative data, including age, weight, height, and body mass index. Fasting serum leptin, glucose, and insulin levels were noted. Homeostasis model assessment scores were calculated. At the postoperative 8th week, patients were reevaluated in terms of above parameters assessing the presence of any difference. Results. Serum leptin levels were decreased postoperatively and the decrease was statistically significant. We were able to show a decrease in homeostasis model assessment score, which indicated an increase in insulin sensitivity, and this change was statistically significant. A significant correlation between body mass index and leptin change was found postoperatively. Conclusion. Reduction mammaplasty is not solely an aesthetic procedure but it decreases serum leptin levels and increases insulin sensitivity, which may help obese women to reduce their cardiovascular risk.

Early weaning and other potential risk factors for overweight among preschool children

OBJECTIVE

To investigate whether early weaning constitutes a risk factor for overweight at preschool age and to identify other factors that affect this association.

METHODS

This was a case-control study of 366 children aged 2 to 6 years (176 boys and 190 girls) from three cities. The case group comprised overweight children, as defined by body mass index (BMI) for age greater than or equal to the 85(th) percentile. The main exposure analyzed was early weaning (exclusive or predominant breastfeeding for less than four months).

RESULTS

Early weaning was a significant risk factor for overweight in univariate analysis (OR = 1.69; 95% CI: 1.10-2.60; p = 0.02), but not in multivariate analysis (OR = 1.42; 95% CI: 0.86-2.34; p = 0.17). Maternal overweight, birth weight > or = 3,500 g and sedentarism were the main risk factors for overweight in multivariate analysis.

DISCUSSION

In our study, the protective effect of breastfeeding against overweight was only shown in univariate analysis; it did not persist after controlling for other variables. It is possible that breastfeeding has only a small protective role against overweight in comparison with other variables of greater importance.

CONCLUSION

Our results suggest that the potential protective effect of breastfeeding against overweight among preschool children is weaker than genetic and other environmental factors.

Effect of surgically removing subcutaneous fat by abdominoplasty on leptin concentrations and insulin sensitivity

The aim of this study was to identify the effect of surgically removing subcutaneous fat by abdominoplasty on leptin concentrations and insulin sensitivity. An open clinical trial with a noninterventional parallel group was carried out in 12 obese women. After randomization, 6 volunteers were selected for abdominoplasty, and the other 6 women were considered as the noninterventional group. A metabolic profile, including leptin concentrations, and insulin tolerance test to assess insulin sensitivity were performed on all volunteers before intervention or nonintervention and 40-50 days afterward. A significant reduction in body mass index (30.7 +/- 0.9 versus 29.6 +/- 0.7 kg/m; P = 0.02) and in leptin concentrations (41.3 +/- 10.6 versus 32.0 +/- 10.2 ng/mL; P = 0.02) was observed after abdominoplasty. Insulin sensitivity did not change after intervention. In conclusion, surgically removing subcutaneous fat by abdominoplasty decreased leptin concentrations, with no change in insulin sensitivity.

Gluten-free diet impact on leptin levels in asymptomatic coeliac adolescents: one year of follow-up

Coeliac disease, daily more frequently diagnosed in our population, involves many organs also in oligosymptomatic patients and with an adequate nutritional regime. Possible endocrine implications include failure to thrive, pubertal delay and reproduction diseases due to deregulation of GH, FSH and LH secretion. Leptin, an adipose tissue hormone, can be decreased as well and its deficiency could be related to growth and puberty anomalies. We studied 14 asymptomatic coeliac patients in peripubertal age (7.5-13.8 years) and tested their leptin levels in order to correlate them with endocrine and anthropometric data. Before the diet was started leptinaemia (M+/-DS) was: 4.94+/-5.53 ng/ml. In 10/14 patients (71%) leptinaemia was<or=2 DS for gender and age. In all the patients, after a period of 6-12 months of gluten-free diet, Leptin levels appreciably raised to 10.8+/-7.9 ng/ml, with a significant correlation to the time of the diet. Leptinaemia was actually lower in patients with a severe mucosal atrophy, and in these patients it increased more significantly after the diet was started. The removal of gluten itself may reduce immunological hit to adipose tissue and the 'malnutrition' of adipocytes: leptin can hence increase despite no significant increase of body mass index occurs. This study could partially explain the correlation between body mass index, Coeliac disease and the deregulation of puberty and fertility, mainly in patients who started the diet late. It could also explain the reversibility of this alteration if the cause is removed.

Postnatal intracerebroventricular exposure to leptin causes an altered adult female phenotype

We investigated the effect of daily intracerebroventricular (ICV) leptin administration (neonatal age 2-7 days) on hypothalamic neuropeptides (neuropeptide Y, alpha-melanocyte-stimulating hormone) that regulate food intake, body weight (BW) gain, and the metabolic/hormonal profile in suckling (8 and 21 days) and adult rat (35, 60, 90, and 120 days). ICV leptin (0.16 mug.g BW(-1).dose(-1); n = 70) led to a postnatal decline in BW (P = 0.0002) that persisted only in the adult females (P = 0.002). The postnatal decline in BW due to leptin was associated with a decline in food intake (P = 0.01) and hypothalamic leptin receptor (P = 0.008) and neuropeptide Y (P = 0.008) immunoreactivities and an increase in alpha-melanocyte-stimulating hormone (P = 0.008) immunoreactivity. In addition, hyperinsulinemia (P = 0.01) with hypocorticosteronemia (P = 0.007) occurred during the postnatal period with hypercorticosteronemia (P = 0.007) and hypoleptinemia (P = 0.008) and an increase in leutinizing hormone (P = 0.01) in the adult male and female progeny. Persistent hyperinsulinemia (P = 0.015) with hyperglycemia (P = 0.008) and glucose intolerance (P = 0.001) were observed only in the adult female. We conclude that postnatal leptin administration alters the adult female phenotype and speculate that this may relate to retention of leptin sensitivity resulting in a lipoatrophic state.

Breast-fed infants have higher leptin values than formula-fed infants in the first four months of life

BACKGROUND

Leptin is a hormone present in breast milk, which regulates food intake and energy metabolism.

AIM

To investigate whether leptin levels are different in breast-fed (BF) or formula-fed (FF) infants in the first months of life.

METHODS

We evaluated serum leptin by radio-immunoassay and anthropometric parameters in 51 infants at the average age of 62.8+/-30 days, 25 exclusively BF and 26 exclusively FF.

RESULTS

Leptin serum values were higher in BF (7.1+/-10.4 ng/ml) than in FF (3.7+/-3.87 ng/ml) infants (p <0.05). Leptin values were higher in females (6.9+/-9.87 ng/ml) than in males (3.5+/-3.88 ng/ml) (p <0.05). No differences were found in anthropometric measurements and body mass index.

CONCLUSION

The kind of feeding might be a factor affecting serum leptin concentration in term infants. The long-term consequences of this difference between BF and FF infants and leptin's role in promoting obesity later in life are unknown.

O aleitamento materno previne o sobrepeso na infância?

OBJETIVOS: investigar se o aleitamento materno tem um efeito protetor contra o sobrepeso na idade pré-escolar. MÉTODOS: estudo de corte transversal com 409 crianças na faixa etária de dois a seis anos, sendo 221 do sexo masculino e 188 do feminino, provenientes de creches vinculadas à prefeitura da cidade de Recife. Foram consideradas expostas as crianças que receberam aleitamento materno exclusivo por menos de quatro meses. O desfecho analisado foi o sobrepeso, definido como índice de massa corporal para idade igual ou superior ao percentil 85. RESULTADOS: dentre as 409 crianças, 11,5% nunca haviam recebido leite materno. A duração média do aleitamento materno foi de 3,97 meses. A prevalência de sobrepeso foi de 18,6%. O sobrepeso foi mais prevalente entre as crianças que receberam leite materno exclusivo por menos de quatro meses (22,5%) do que entre aquelas que receberam leite materno exclusivo por quatro meses ou mais (13,5%) (p = 0,03). CONCLUSÕES: em nosso estudo, o aleitamento materno apresentou um efeito protetor contra o sobrepeso na idade pré-escolar.

[The tumor necrosis factor system and leptin in coeliac disease]

OBJECTIVE

Patients with coeliac disease (CD) present anorexia and malnutrition. Leptin is a significant anorexigenic factor, with a close relationship to the body mass index. The aims of this study were to asses serum leptin levels in CD and their possible influence on appetite, as well as to compare and relate leptin with tumor necrosis factor (TNF) activity, which has similar functions.

METHODS

Leptin and TNF receptor-1 (TNFr-1) were measured by enzyme-linked immunosorbent assay. Sixty-five serum samples from patients with CD (28 boys and 37 girls) were analyzed. In all patients, small bowel biopsy and anti-endomysium determination were performed simultaneously. Twenty-nine patients presented active CD and 36 were in remission.

RESULTS

Leptin concentrations were reduced in active CD (p = 0.002). In patients in remission, leptin was related to the body mass index (p = 0.001), but this correlation was not found during the active phase of the disease. Contrary to normal differences between sexes, in active CD leptin levels were similar in boys and girls. TNFr-1 was found in all serum samples and levels were statistically higher in patients with active CD (p = 0.0003), suggesting that the TNF system is activated in this disease.

CONCLUSIONS

Leptin concentrations were reduced in active CD, but we did not find the usual positive correlation with body mass index and higher concentrations in girls. These results suggest that leptin does not contribute to anorexia and failure to thrive in patients with CD; in contrast, the TNF system might be involved.

Neurohumoral regulation of body weight gain

The regulation of body weight is a complex process which relies on a balance between supply of nutrients and demand on these nutrients in the form of energy expenditure. Various central and peripheral mechanisms play a crucial role in maintaining this balance. While various neuropeptides in the central nervous system (CNS), particularly in the hypothalamus, maintain the necessary harmony between hyperphagia and anorexia, peripheral signals arising from the gastrointestinal tract (cholecystokinin-8 [CCK-8], amylin), pancreas (insulin) and adipose tissue (leptin) provide the necessary stimuli or a feedback inhibition for the synthesis and secretion of these hypothalamic neuropeptides. Various metabolites of the carbohydrate and fat metabolism are also involved in regulating the neuronal activity in the hypothalamus which ultimately leads to a release of key neuropeptides. In addition to the central mechanisms, peripheral mechanisms that regulate energy expenditure, particularly in the brown adipose tissue and skeletal muscle, are critical in maintaining the overall balance. Insight into these mechanisms sets the stage for developing novel strategies in the treatment of emerging childhood diseases such as obesity, anorexia nervosa, and bulimia. Further, delineation of these processes in the fetus and newborn sets the stage for investigating their role in molding the adult phenotype due to intrauterine adaptations.

Leptin: pathogenesis and treatment of morbid obesity

Leptin is a hormone produced primarily by the adipocytes. It works through different receptors and seems to provide information to the hypothalamus about the energy status of the body. Although leptin appears to exert its anti-obesity effect through its central action, the full spectrum of its action is yet to be determined. Most obese subjects in studies have high serum levels of leptin, suggesting that the major problem is leptin resistance rather than leptin deficiency. Consequently, these patients may not respond to exogenous leptin. Recent trials have indicated, however, that leptin may have therapeutic potential in leptin-deficient as well as leptin-resistant states.