Relationship between concentration of serum leptin and fetal growth

Measurement of Calprotectin and PTH in the Amniotic Fluid of Early Second Trimester Pregnancies and Their Impact on Fetuses with Growth Disorders: Are Their Levels Related to Oxidative Stress?

Background: During the early stages of human fetal development, the fetal skeleton system is chiefly made up of cartilage, which is gradually replaced by bone. Fetal bone development is mainly regulated by the parathyroid hormone parathormone (PTH) and PTH-related protein, with specific calprotectin playing a substantial role in cell adhesion and chemotaxis while exhibiting antimicrobial activity during the inflammatory osteogenesis process. The aim of our study was to measure the levels of PTH and calprotectin in early second trimester amniotic fluid and to carry out a comparison between the levels observed among normal full-term pregnancies (control group) and those of the groups of embryos exhibiting impaired or enhanced growth. Methods: For the present prospective study, we collected amniotic fluid samples from pregnancies that underwent amniocentesis at 15 to 22 weeks of gestational age during the period 2021-2023. Subsequently, we followed up on all pregnancies closely until delivery. Having recorded fetal birthweights, we then divided the neonates into three groups: small for gestational age (SGA), appropriate for gestational age (AGA), and large for gestational age (LGA). Results: In total, 64 pregnancies, including 14 SGA, 10 LGA, and 40 AGA fetuses, were included in our study. Both substances were detected in early second trimester amniotic fluid in both groups. Concentrations of calprotectin differed significantly among the three groups (p = 0.033). AGA fetuses had a lower mean value of 4.195 (2.415-6.425) IU/mL, whereas LGA fetuses had a higher mean value of 6.055 (4.887-13.950) IU/mL, while SGA fetuses had a mean value of 5.475 (3.400-9.177) IU/mL. Further analysis revealed that only LGA fetuses had significantly higher calprotectin concentrations compared to AGA fetuses (p = 0.018). PTH concentration was similar between the groups, with LGA fetuses having a mean value of 13.18 (9.51-15.52) IU/mL, while SGA fetuses had a mean value of 14.18 (9.02-16.00) IU/mL, and AGA fetuses had similar concentrations of 13.35 (9.05-15.81) IU/mL. The differences in PTH concentration among the three groups were not statistically significant (p = 0.513). Conclusions: Calprotectin values in the amniotic fluid in the early second trimester were higher in LGA fetuses compared to those in the SGA and AGA categories. LGA fetuses can possibly be in a state of low-grade chronic inflammation due to excessive fat deposition, causing oxidative stress in LGA fetuses and, eventually, the release of calprotectin. Moreover, PTH concentrations in the amniotic fluid of early second trimester pregnancies were not found to be statistically correlated with fetal growth abnormalities in either LGA or SGA fetuses. However, the early time of collection and the small number of patients in our study should be taken into account.

Pathomechanisms of Prenatally Programmed Adult Diseases

Based on epidemiological observations Barker et al. put forward the hypothesis/concept that an adverse intrauterine environment (involving an insufficient nutrient supply, chronic hypoxia, stress, and toxic substances) is an important risk factor for the development of chronic diseases later in life. The fetus responds to the unfavorable environment with adaptive reactions, which ensure survival in the short run, but at the expense of initiating pathological processes leading to adult diseases. In this review, the major mechanisms (including telomere dysfunction, epigenetic modifications, and cardiovascular-renal-endocrine-metabolic reactions) will be outlined, with a particular emphasis on the role of oxidative stress in the fetal origin of adult diseases.

Fetal Doppler in monochorionic pregnancies complicated by twin-to-twin transfusion syndrome and selective in utero growth restriction

BACKGROUND

Monochorionic (MC) twin pregnancies may be complicated by placental pathologies that impact fetal cardiac function, such as twin-twin transfusion syndrome (TTTS) and selective intrauterine growth-restriction (sIUGR). In the TTTS, the unbalanced blood flow through placental anastomoses lead a recipient volume overload, hypertension and hypertrophic cardiomyopathy and the donor twin experiences hypovolemia and hypertension due to increased placental resistance and poor renal perfusion. When MC pregnancies were complicated by sIUGR, the increase of placental resistances lead to complex fetal compensatory mechanisms with redistribution of cardiac output to vital organs. Increased placental vascular resistances, hypoxia and hemodynamic compensation mechanisms lead to higher pre and/or afterload for both ventricles, right cardiac failure and eventually left cardiac failure observed just before fetal death.

OBJECTIVES

The purpose of this study was to describe the anomalies of umbilical, ductal and aortic isthmic Doppler as well as left and right myocardial performance index (MPI) across various clinical phenotypes of MC twin pregnancies, uncomplicated or complicated by TTTS or sIUGR, in order to help differentiating these conditions and to improve the understanding of TTTS and sIUGR pathophysiology.

STUDY DESIGN

Aortic isthmic systolic index (ISI), umbilical artery pulsatility index (UAPI), ductus venosus pulsatility index (DVPI), and MPI were studied in uncomplicated MC twins (control group) and cases of sIUGR or TTTS.

RESULTS

The measurements were obtained in 113 pregnancies (24 uncomplicated, 22 sIUGR, 51 TTTS). In comparison with controls, the sIUGR smaller twin sets had lower ISI and higher UAPI, and the larger twin had higher ISI. The TTTS donor and recipient had lower ISI, higher UAPI and DVPI. Compared to the co-twin, the ISI values were lower in the sIUGR smaller twin and the TTTS donor had lower ISI and MPI. Comparing TTTS and sIUGR, the recipient had higher DVPI and MPI than the sIUGR larger twin.

CONCLUSIONS

The Doppler anomalies observed in the smaller twin reflected increased placental blood flow resistance, presumably due to abnormal feto-fetal transfusion in TTTS and to unequal placental sharing in sIUGR. Early hemodynamic changes suggestive of cardiac overload in the recipient twin may help to differentiate TTTS and sIUGR.

The interactive effect of pre-pregnancy overweight and obesity and hypertensive disorders of pregnancy on the weight status in infancy

We aimed to assess whether hypertensive disorders of pregnancy (HDP) could modify the effect of pre-pregnancy overweight or obesity (OWO) on the risk of offspring high body mass index (BMI) in infancy. A total of 3,765 mother-child pairs were recruited from two Chinese birth cohorts. BMI ≥ 85^th percentile, based on World Health Organization criteria, was defined as a high BMI for the risk of developing severe obesity in later life. Logistic regression analysis was used to assess the combined effects and multiplicative interactions of pre-pregnancy OWO + HDP on offspring high BMI. Relative excess risk due to interaction (RERI) or attributable proportion (AP) was used to estimate additive interactions. RERI > 0 or AP > 0 indicates a significant additive interaction. Compared with the non-OWO and normal blood pressure group, the combination of OWO + HDP was positively associated with offspring high BMI at 12 months of age [OR 3.10 (95%CI 1.59, 6.04)], with 51% of the effects attributed to an additive interaction [AP 0.51 (95%CI 0.13, 0.89)]. An interactive effect was found between the pre-pregnancy OWO + HDP and offspring high BMI in infancy. Interventions to control pre-pregnancy OWO and HDP are important to prevent obesity and associated adverse outcomes in offspring.

BCG scar, socioeconomic and nutritional status: a study of newborns in urban area of Makassar, Indonesia

Objective

To investigate factors that determine the response to Bacille Calmette–Guérin (BCG) vaccination in urban environments with respect to socioeconomic status (SES), prenatal exposure to infections or newborn's nutritional status.

Methods

The study was conducted in an urban area, in Makassar, Indonesia. At baseline, 100 mother and newborns pair from high and low SES communities were included. Intestinal protozoa, soil transmitted helminths, total IgE, anti‐Hepatitis A Virus IgG and anti‐Toxoplasma IgG were measured to determine exposure to infections. Information on gestational age, birth weight/height and delivery status were collected. Weight‐for‐length z‐score, a proxy for newborns adiposity, was calculated. Leptin and adiponectin from cord sera were also measured. At 10 months of age, BCG scar size was measured from 59 infants. Statistical modelling was performed using multiple linear regression.

Results

Both SES and birth nutritional status shape the response towards BCG vaccination at 10 months of age. Infants born to low SES families have smaller BCG scar size compared to infants born from high SES families and total IgE contributed to the reduced scar size. On the other hand, infants born with better nutritional status were found to have bigger BCG scar size but this association was abolished by leptin levels at birth.

Conclusion

This study provides new insights into the importance of SES and leptin levels at birth on the development of BCG scar in 10 months old infants.

Visual Function and Fundus Morphology in Relation to Growth and Cardiovascular Status in 10-Year-Old Moderate-to-Late Preterm Children

PURPOSE

To study visual function and ocular fundus morphology in relation to growth, metabolic status, and blood pressure in moderate-to-late preterm (MLP) children at 10 years of age.

DESIGN

Prospective cohort study.

METHODS

In this population-based observational study, nonsyndromic MLP children born in Gothenburg, Sweden, were examined neonatally in the years 2002-2003 concerning length, weight, head circumference, and insulin-like growth factor I (IGF-I). At 10 years of age, 33 children (10 girls) were examined regarding previously mentioned variables, and regarding visual acuity, refraction, fundus morphology, IGF binding protein 3, leptin, adiponectin, and blood pressure. An age- and sex-matched control group consisted of 28 children (9 girls).

RESULTS

Myopia was more commonly found in MLP children than in controls (P = .004, 95% CI 1.8 to 49.8). The MLP group had smaller optic disc area (P = .01, 95% CI -0.5 to -0.1), smaller rim area (P = .001, 95% CI -0.5 to -0.2), fewer branching points (P = .0001, 95% CI -5.7 to -2.1), and higher index of tortuosity of arteries (P = .03, 95% CI 0.002 to 0.03) and veins (P = .02, 95% CI 0.003 to 0.02). Refraction correlated with IGF-I (P = .0005, r_s = 0.60 in right eye, and P = .002, r_s = 0.55 in left eye) at 10 years of age. Tortuosity of arteries at assessment correlated with neonatal IGF-I levels (P = .03, r_s = -0.39). Tortuosity of veins correlated with a leptin/adiponectin ratio at assessment (P = .04, r_s = 0.37).

CONCLUSION

The findings suggest that being born MLP is associated with myopia, smaller optic disc and rim areas, and abnormal retinal vascularization. Furthermore, metabolic status and growth factors seem to have an impact on ocular development.

Fetal and Infancy Growth Pattern, Cord and Early Childhood Plasma Leptin, and Development of Autism Spectrum Disorder in the Boston Birth Cohort

Leptin is a proinflammatory cytokine that plays an important role in energy homeostasis. Emerging evidence suggests that leptin levels are altered in children with autism spectrum disorder (ASD); however, this has not been studied prospectively. Rapid growth during infancy and early childhood has been implicated in ASD, but the evidence is inconsistent. As leptin is involved in growth and is a potential risk factor for ASD, we explored the associations between (a) cord, early childhood leptin and ASD; and (b) birth weight for gestational age, early childhood weight gain, and ASD. We also assessed the mediating role of leptin in the relationship between weight gain during infancy and ASD. This study was conducted in a sample of 822 subjects from the Boston Birth Cohort. ASD was defined from diagnostic codes in electronic medical records. Extremely rapid weight gain during infancy was associated with a greater ASD risk and this persisted after adjusting for potential confounders (aOR: 3.11; 95% CI: 1.37, 7.07). Similarly, children that had higher plasma leptin levels, prior to ASD diagnosis, had an increased ASD risk in both unadjusted and adjusted models (aOR: 7.87; 95% CI: 2.06, 30.04). Further, early childhood leptin indirectly mediated the relationship between rapid weight gain and ASD. No associations were found between birth weight for gestational age, cord leptin and risk of ASD. Our findings provide a basis to further explore whether the combination of early life growth pattern and a biomarker such as leptin can predict ASD earlier. Autism Res 2018, 11: 1416-1431. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Is early life growth and a biomarker leptin related to ASD risk? To answer this question, we followed 822 children from birth and found that those who gained weight very quickly in infancy, had higher leptin levels in early childhood, had a greater chance of later ASD diagnosis. More research is needed to see if infant's weight gain pattern along with a biomarker (such as leptin) can be used to identify children with ASD sooner.

Serum Concentration of Leptin in Pregnant Adolescents Correlated with Gestational Weight Gain, Postpartum Weight Retention and Newborn Weight/Length

Introduction: Gestational weight gain is an important modifiable factor known to influence fetal outcomes including birth weight and adiposity. Leptin is normally correlated with adiposity and is also known to increase throughout pregnancy, as the placenta becomes a source of leptin synthesis. Several studies have reported positive correlations between cord blood leptin level and either birthweight or size for gestational age, as well as body mass index (BMI). Objective: To determine the correlation of prenatal leptin concentration in pregnant adolescents with their gestational weight gain, postpartum weight retention, and weight/length of their newborn. Methods: A cohort study was conducted on pregnant Mexican adolescents from Gestational Week 26–28 to three months postpartum (n = 168 mother–child dyads). An anthropometric assessment was made of each pregnant adolescent, and the serum level of leptin and the intake of energy were determined. The newborn was evaluated each month during postpartum. Clinical records were reviewed to obtain sociodemographic data. Bivariate correlations, tests for repeating measurements and logistic regression models were performed. Results: Leptin concentration gradually increased during the third trimester of pregnancy. At Gestation Week 36, leptin level correlated with gestational weight gain. When comparing adolescents that had the lowest and highest concentration of leptin, the former presented a mean of 6 kg less in gestational weight gain (inter-subject leptin concentration, p = 0.001; inter-subject energy intake, p = 0.497). Leptin concentration and gestational weight gain exerted an effect on the weight of the newborn (inter-subject leptin concentration for Week 32, p = 0.024; inter-subject gestational weight gain, p = 0.011). Newborn length was associated with leptin concentration at Week 28 (leptin effect, p = 0.003; effect of gestational weight gain, p = 0.722). Conclusions: Pregnant adolescents with leptin concentration over 20 ng/mL showed a greater gestational weight gain. Leptin concentration correlated with length and weight of the newborn.

Relationship between insulin-like growth factor 1, leptin and ghrelin levels and catch-up growth in small for gestational age infants of 27-31 weeks during neonatal intensive care unit admission

AIM

Poor post-natal growth is related to later morbidity and poor cognitive development in preterm infants. We investigated the relationship between plasma insulin-like growth factor 1 (IGF-1), leptin, active ghrelin levels and post-natal growth in preterm infants small for gestational age (SGA).

METHODS

Plasma IGF-1, leptin and active ghrelin levels were measured at birth and at 2, 4, 6 and 8 weeks after birth in 42 very low birthweight (VLBW) infants (born between 27 and 31 weeks of gestation), including 14 SGA infants with extrauterine growth restriction (EUGR), 6 SGA infants without EUGR and 22 appropriate-for-gestational-age infants.

RESULTS

At birth, IGF-1 levels in SGA infants without EUGR did not differ significantly from those in SGA infants with EUGR. However, IGF-1 levels in SGA infants without EUGR were as high as those observed in appropriate-for-gestational-age infants and were significantly different from those in SGA infants with EUGR at 4 and 8 weeks of age. Leptin and ghrelin levels did not differ significantly among the three groups at any time point.

CONCLUSION

IGF-1 is related to catch-up growth in SGA VLBW infants during neonatal intensive care unit admission; however, this does not appear to be the case for leptin and ghrelin. IGF-1 level monitoring may be useful for predicting EUGR in preterm VLBW infants.

Modeling the impact of growth and leptin deficits on the neuronal regulation of blood pressure

The risk of hypertension is increased by intrauterine growth restriction (IUGR) and preterm birth. In the search for modifiable etiologies for this life-threatening cardiovascular morbidity, a number of pathways have been investigated, including excessive glucocorticoid exposure, nutritional deficiency and aberration in sex hormone levels. As a neurotrophic hormone that is intimately involved in the cardiovascular regulation and whose levels are influenced by glucocorticoids, nutritional status and sex hormones, leptin has emerged as a putative etiologic and thus a therapeutic agent. As a product of maternal and late fetal adipocytes and the placenta, circulating leptin typically surges late in gestation and declines after delivery until the infant consumes sufficient leptin-containing breast milk or accrues sufficient leptin-secreting adipose tissue to reestablish the circulating levels. The leptin deficiency seen in IUGR infants is a multifactorial manifestation of placental insufficiency, exaggerated glucocorticoid exposure and fetal adipose deficit. The preterm infant suffers from the same cascade of events, including separation from the placenta, antenatal steroid exposure and persistently underdeveloped adipose depots. Preterm infants remain leptin deficient beyond term gestation, rendering them susceptible to neurodevelopmental impairment and subsequent cardiovascular dysregulation. This pathologic pathway is efficiently modeled by placing neonatal mice into atypically large litters, thereby recapitulating the perinatal growth restriction-adult hypertension phenotype. In this model, neonatal leptin supplementation restores the physiologic leptin surge, attenuates the leptin-triggered sympathetic activation in adulthood and prevents leptin- or stress-evoked hypertension. Further pathway interrogation and clinical translation are needed to fully test the therapeutic potential of perinatal leptin supplementation.

Plasma leptin concentration in pre- and post-weaning lambs

Leptin has an important rôle in the control of appetite and energy expenditure. Several studies have reported the effects of leptin in ruminants. However, little is known about changes in circulating leptin concentrations in neonates of ruminant species, or the effects of weaning on plasma leptin concentrations. The main objectives of this experiment were: to examine plasma leptin concentrations in lambs, in the period from just after birth through to weaning; to examine the effect of weaning on plasma leptin concentrations, and to compare leptin concentrations measured using a ‘multi-species’ leptin radio-immunoassay (RIA) kit and a specific ovine RIA in lambs during the 6-month period after weaning. In a previous paper, we reported leptin concentrations using a commercial RIA during the post-weaning period. However, we were not able to measure plasma leptin concentrations from just after birth to weaning as they were apparently below the level of sensitivity of the assay. In the present study, five crossbred lambs were removed from their dams within 2 days after birth, and bottle-fed on milk replacer at a level sufficient to meet a 1•2 times maintenance metabolizable energy intake. Lambs were weaned 45 days after birth, and housed individually in pens. The lambs were offered timothy hay, rolled barley and soya-bean meal to meet a 200 g daily gain during the post-weaning period. During the pre-weaning period, blood samples were collected within 5 h of birth and thereafter at 09:00 h; every day from 2 to 6 days of age; at 2-day intervals from 6 to 14 days of age; and at 3-day intervals from 14 to 45 days of age. During the post-weaning period, blood samples were collected before and 3 and 6 h after the morning meal at the ages of 0•5, 1, 2, 3, 4, 5 and 6 months. Plasma leptin concentrations slightly increased (P < 0•05) just after birth and then remained constant until 45 days old (P > 0•05). Additionally, plasma leptin concentration was not significantly changed following weaning. During the post-weaning period, plasma leptin concentrations were compared using two RIA systems. The correlation between plasma leptin concentrations measured by the ‘multi-species’ leptin RIA kit and specific ovine RIA was poor (r = 0•41). These findings are consistent with other reports and suggest that the ‘multi-species’ leptin RIA kit is not suitable for estimating leptin plasma concentrations in ruminants.

Neonatal adiposity increases with rising cord blood IGF-1 levels

OBJECTIVE

Infants with higher adiposity at birth may be at greater risk of developing obesity later in life. IGF-1 is important for intrauterine growth and may be a useful early life marker of adiposity, and thus later obesity risk. The aim of this study was to determine the relationship between cord blood IGF-1, neonatal anthropometrics and markers of neonatal adiposity.

DESIGN, PATIENTS AND MEASUREMENTS

A cross-sectional study design was utilized to study a multiethnic cohort of full-term neonates born to healthy mothers with normal glucose tolerance at a large university hospital. Neonatal cord blood was collected after birth and assayed for IGF-1, leptin and C-peptide. Neonatal body composition was measured between 24 and 72 h of life using the method of air displacement plethysmography.

RESULTS

Cord blood IGF-1 was positively and significantly associated with markers of neonatal adiposity in models adjusted for maternal age at delivery, race, maternal prepregnancy BMI, gestational age at delivery and neonatal sex: birthweight (r = 0·62, P < 0·001), leptin (r = 0·33, P = 0·018), fat mass (r = 0·52, P < 0·001) and percent body fat (r = 0·51, P < 0·001). Cord blood IGF-1 was not associated with cord blood C-peptide.

CONCLUSIONS

Cord blood IGF-1 is strongly associated with all measures of neonatal adiposity suggesting that IGF-1 may be an important contributor to in utero neonatal fat accumulation.

Relationship between fat mass measured by dual-energy X-ray absorptiometry and leptin in preterm infants between term age and 6 months' corrected age

BACKGROUND/AIMS

In term subjects, fat mass (FM) is positively associated with leptin, whereas studies in preterm infants show conflicting results. However, none of these studies measured FM by dual-energy X-ray absorptiometry (DEXA). This study aims to relate FM measured by DEXA in relation to leptin and growth in preterm infants.

METHODS

In 139 preterm infants, weight (kg) and length (cm) were measured at birth, term age, and 6 months' corrected age (CA). FM (kg), measured by whole-body DEXA, and leptin (µg/l) were measured at term age and 6 months' CA.

RESULTS

At term age and 6 months' CA, FM was associated with leptin (β = 1.94, 95% CI: 1.51-2.36, and β = 0.37, 95% CI: 0.26-0.48, respectively; p < 0.001). Gain in weight standard deviation score (SDS) between term age and 6 months' CA was associated with FM and leptin at 6 months' CA (β = 0.24, 95% CI: 0.18-0.30, and β = 0.25, 95% CI: 0.16-0.33, respectively; p < 0.001).

CONCLUSION

In preterm infants, FM measured by DEXA is associated with leptin, which indicates that leptin is a marker of body FM during the first 6 months after term age. Gain in weight SDS between term age and 6 months' CA results in higher FM and higher leptin at 6 months' CA.

Role of leptin in female reproduction

Reproductive function is dependent on energy resources. The role of weight, body composition, fat distribution and the effect of diet have been largely investigated in experimental female animals as well as in women. Any alteration in diet and/or weight may induce abnormalities in timing of sexual maturation and fertility. However, the cellular mechanisms involved in the fine coordination of energy balance and reproduction are largely unknown. The brain and hypothalamic structures receive endocrine and/or metabolic signals providing information on the nutritional status and the degree of fat stores. Adipose tissue acts both as a store of energy and as an active endocrine organ, secreting a large number of biologically important molecules termed adipokines. Adipokines have been shown to be involved in regulation of the reproductive functions. The first adipokine described was leptin. Extensive research over the last 10 years has shown that leptin is not only an adipose tissue-derived messenger of the amount of energy stores to the brain, but also a crucial hormone/cytokine for a number of diverse physiological processes, such as inflammation, angiogenesis, hematopoiesis, immune function, and most importantly, reproduction. Leptin plays an integral role in the normal physiology of the reproductive system with complex interactions at all levels of the hypothalamic-pituitary gonadal (HPG) axis. In addition, leptin is also produced by placenta, where it plays an important autocrine function. Observational studies have demonstrated that states of leptin excess, deficiency, or resistance can be associated with abnormal reproductive function. This review focuses on the leptin action in female reproduction.

Association between maternal urinary arsenic species and infant cord blood leptin levels in a New Hampshire Pregnancy Cohort

Leptin is an important pleiotropic hormone involved in the regulation of nutrient intake and energy expenditure, and is known to influence body weight in infants and adults. High maternal levels of arsenic have been associated with reduced infant birth weight, but the mechanism of action is not yet understood. This study aimed to investigate the association between in utero arsenic exposure and infant cord blood leptin concentrations within 156 mother-infant pairs from the New Hampshire Birth Cohort Study (NHBCS) who were exposed to low to moderate levels of arsenic through well water and diet. In utero arsenic exposure was obtained from maternal second trimester urinary arsenic concentration, and plasma leptin levels were assessed through immunoassay. Results indicate that urinary arsenic species concentrations were predictive of infant cord blood leptin levels following adjustment for creatinine, infant birth weight for gestational age percentile, infant sex, maternal pregnancy-related weight gain, and maternal education level amongst 149 white mother-infant pairs in multivariate linear regression models. A doubling or 100% increase in total urinary arsenic concentration (iAs+MMA+DMA) was associated with a 10.3% (95% CI: 0.8-20.7%) increase in cord blood leptin levels. A 100% increase in either monomethylarsonic acid (MMA) or dimethylarsinic acid (DMA) was also associated with an 8.3% (95% CI: -1.0-18.6%) and 10.3% (95% CI: 1.2-20.2%) increase in cord blood leptin levels, respectively. The association between inorganic arsenic (iAs) and cord blood leptin was of similar magnitude and direction as other arsenic species (a 100% increase in iAs was associated with a 6.5% (95% CI: -3.4-17.5%) increase in cord blood leptin levels), albeit not significant. These results suggest in utero exposure to low levels of arsenic influences cord blood leptin concentration and presents a potential mechanism by which arsenic may impact early childhood growth.

Fasting and postprandial glucose, insulin, leptin, and ghrelin values in preterm babies and their mothers: relationships among their levels, fetal growth, and neonatal anthropometry

OBJECTIVE

To investigate relationship between anthropometric values of premature babies with their's glucose, insulin, leptin, and ghrelin at birth and on day 15.

METHODS

We analyzed fasting and postprandial glucose, insulin, leptin, and ghrelin levels at birth and on day 15 in babies born prematurely between 24 and 37 weeks, and who did not have serious problems aside from prematurity at birth.

RESULTS

Fasting glucose, insulin, leptin and ghrelin values of babies at birth and on day 15 were significantly lower than postprandial values (all p values p < 0.001). There were positive correlations between the mean insulin, leptin, and ghrelin levels with the gestational age, birth weight, body mass index, head circumference of babies at birth, and anthropometric values on day 15 (all r values > 0.400, all p values < 0.05). Fasting glucose, leptin, and ghrelin values of mothers birth were significantly lower than post-prandial values (all p values p < 0.05).

CONCLUSIONS

The positive correlations between the insulin, leptin, and ghrelin values of babies at birth with gestational age and anthropometric values suggest that both hormones play important roles in fetal and neonatal growth and development.

Maternal serum leptin during pregnancy and infant birth weight: the influence of maternal overweight and obesity

OBJECTIVE

Few studies have examined whether the distinct metabolic patterns found in obese and nonobese pregnant women have different effects on the growing fetus. Our objective was to estimate the influence of longitudinal variation in maternal serum leptin levels on variation in infant birth weight in overweight/obese versus normal-weight women.

DESIGN AND METHODS

In a prospective cohort of 286 gravidas, maternal weight and serum leptin levels at 6-10, 10-14, 16-20, 22-26, and 32-36 weeks gestation were measured. Effects of leptin levels on infant birth weight adjusted for gestational age at delivery (aBW) were analyzed using a linear regression model that accounted for the relationship of time-varying predictors to the log-transformed leptin concentrations.

RESULTS

Different relationships of aBW to maternal serum leptin and its rate of change across pregnancy were exhibited by overweight/obese and normal-weight gravidas. For normal-weight women, aBW is not associated with either the magnitude of the logarithm of the leptin concentration or with its rate of change in either the first or second half of pregnancy. Conversely, for overweight/obese women, an increase in the rate of change in maternal serum leptin in the second half of pregnancy is significantly associated with a decrease in aBW. This effect is distinct from that of maternal weight.

CONCLUSION

Differences in the effect of maternal serum leptin on fetal growth between overweight/ obese and normal-weight women suggest metabolic and physiologic heterogeneity between these groups. Such differences may be involved in the long-term physiologic effects of the obese intrauterine environment on the health of the offspring.

Influence of pre- and peri-natal nutrition on skeletal acquisition and maintenance

Early life nutrition has substantial influences on postnatal health, with both under- and overnutrition linked with permanent metabolic changes that alter reproductive and immune function and significantly increase metabolic disease risk in offspring. Since perinatal nutrition depends in part on maternal metabolic condition, maternal diet during gestation and lactation is a risk factor for adult metabolic disease. Such developmental responses may be adaptive, but might also result from constraints on, or pathological changes to, normal physiology. The rising prevalence of both obesity and osteoporosis, and the identification of links among bone, fat, brain, and gut, suggest that obesity and osteoporosis may be related, and moreover that their roots may lie in early life. Here we focus on evidence for how maternal diet during gestation and lactation affects metabolism and skeletal acquisition in humans and in animal models. We consider the effects of overall caloric restriction, and macronutrient imbalances including high fat, high sucrose, and low protein, compared to normal diet. We then discuss potential mechanisms underlying the skeletal responses, including perinatal developmental programming via disruption of the perinatal leptin surge and/or epigenetic changes, to highlight unanswered questions and identify the most critical areas for future research.

The influence of overweight and obesity on longitudinal trends in maternal serum leptin levels during pregnancy

Maternal obesity influences a number of metabolic factors that can affect the course of pregnancy. Among these factors, leptin plays an important role in energy metabolism and fetal development during pregnancy. Our objective was to estimate the influence of maternal overweight/obesity on variation in the maternal serum leptin profile during pregnancy. In a prospective cohort of 143 adult gravidas with singleton pregnancies presenting for general prenatal care, we measured serum leptin levels at 6-10, 10-14, 16-20, 22-26, and 32-36 weeks' gestation. The longitudinal effects of maternal prepregnancy BMI, categorized as nonoverweight (≤ 26.0 kg/m(2)) and overweight/obese (>26.0 kg/m(2)), on serum leptin concentration were analyzed using linear mixed models. Overweight/obese women had significantly higher serum leptin concentrations than their nonoverweight counterparts throughout pregnancy (P < 0.01). Although these concentrations increased significantly across gestation for both groups, the rate of increase was significantly smaller for overweight/obese women (P < 0.05). To investigate whether these differences merely reflected differences in weight-gain patterns between the two groups, we examined an index of leptin concentration per unit body weight (leptin (ng/ml)/weight (kg)). Overweight/obese women had a significantly higher index throughout pregnancy (P < 0.01). However, although this index increased significantly across pregnancy for nonoverweight women, it actually decreased significantly for overweight/obese women (P < 0.01). Our results suggest that factors other than fat mass alone influence leptin concentrations in overweight/obese women compared to normal-weight women during pregnancy. Such factors may contribute to differences in the intrauterine environment and its influence on pregnancy outcomes in the two groups.

Influence of maternal diabetes on serum leptinemic and insulinemic status of the offspring: a case study of selected patients in a tertiary care hospital in Bangladesh

INTRODUCTION

Leptin is now known to be an important hormone affecting intrauterine fetal growth. Since growth of fetus is also affected by the glycemic status of the mother. Serum leptin of infant is influenced by the maternal diabetic state. Investigation of cord blood leptin in babies of DM (Diabetes Mellitus) and GDM (Gestational Diabetes Mellitus) mothers (controlled blood glucose levels) may provide some indication about involvement of genetic factor in the development of leptin abnormalities in fetus.

AIM

The study was taken to investigate whether cord blood insulin, c-peptide and leptin levels correlate with birth weight in offspring of DM mother.

METHODS

Blood was drawn from umbilical cord of 30 babies from GDM mothers (GDM-babies), 45 babies from Type 2 DM Mothers (DM-babies), and 30 babies from ND (Nondiabetic) mothers (ND-babies) of term pregnancy. Weight, blood glucose, placenta, serum leptin and c-peptide of the babies were measured.

RESULTS

Birth weight of GDM and DM babies were significantly higher compared to ND-babies. Glucose level in GDM babies was significantly higher than ND and DM babies. Leptin levels in GDM babies were significantly higher than that of ND and DM babies. Serum c-peptide in GDM babies was significantly higher than DM and ND babies. However, there was no significant difference in leptin-glucose ratio among the three groups. Irrespective of degree of hyperglycemia leptin is a major determinant of fetal growth.

CONCLUSIONS

DM mother produces different insulinemic and leptinemic responses in the fetus indicating a possible genetic involvement.

A meta-analysis of relationship between birth weight and cord blood leptin levels in newborns

CONTEXT

Low cord blood leptin concentration is implicated as a risk factor for small for gestational age (SGA) babies. However, the association of strength, consistency, independence, and confounding factors of this affliction has not been systematically examined.

OBJECTIVE

To determine if there is a difference in cord blood leptin concentration between SGA and appropriate for gestational age (AGA) newborns, and to observe whether the sample origins, GA, pregnancy-induced hypertension (PIH) and congenital malformation (CM) are confounding factors of the meta-analysis.

DATA SOURCES AND STUDY SELECTION

Relevant studies published between 1996 and 2007 were identified through literature searches using Ovid, Medline, PubMed, Web of Science, National Knowledge Infrastructure, Wanfang Data, and VIP China Scientific Journal Database, based on the following key words: leptin, intrauterine growth restriction, intrauterine growth retardation, fetal growth restriction, and small for gestational age.

DATA EXTRACTION

A meta-analysis was conducted to analyze the difference of the cord blood leptin concentrations between SGA and AGA newborns. Then the stratified meta-analyses were repeated with a multivariate model to adjust for potential confounders, i.e., samples origin (Chinese newborns vs. non-Chinese newborns), GA (the term-newborns vs. the mixed GA newborns), PIH or CM (the newborns excluding PIH or CM vs. the newborns not excluding PIH or CM).

DATA SYNTHESIS

Twenty articles including 514 SGA newborns and 1006 AGA newborns were collected. The cord leptin concentrations of SGA newborns were lower than those of AGA newborns [WMD (95%CI), -4.42 (-5.54, -3.29) ng/ml; P<0.01; n=1520 newborns]. The results of stratified meta-analyses showed similar results in Chinese vs. non-Chinese newborns and term vs. mixed GA newborns, respectively. However, the newborns not excluding PIH or CM had a wider 95%CI than the newborns excluding PIH or CM [WMD (95%CI), -4.17 (-5.00, -3.33) ng/ml vs. -4.47 (-9.61, 0.67) ng/ml)], and there was no significant difference in cord blood leptin concentrations between SGA and AGA newborns in the newborns not excluding PIH or CM (P=0.09).

CONCLUSIONS

SGA babies have low cord leptin concentrations. Other factors that may influence cord leptin levels are maternal PIH and CM.

Correlation between maternal first trimester plasma leptin levels and birth weight among normotensive and preeclamptic women

OBJECTIVE

To determine the connection between maternal first trimester serum leptin levels and newborn weight.

METHODS

The study included 37 preeclamptic women and 53 normotensive women who considered the control group. Maternal blood samples were withdrawn at 13 weeks of gestation for the measurement of leptin concentrations. Birth weights were transformed to z-scores according to maternal and obstetrical features, based on customized centiles. Non-parametric tests, student's t-test, Pearson's correlation, Spearman's correlation and linear regression analysis were performed in our analysis.

RESULTS

Pre-pregnancy body mass index and first trimester maternal plasma leptin levels were significantly higher among women with preeclampsia (p=0.015 and p<0.001, respectively). Birth weight z-score was negatively correlated with leptin levels (r= -0.570, p<0.001), in preeclamptic group and in control group (r= -0.477, p<0.001). The regression modelling demonstrated a significant negative association between birth weight z-scores and leptin for both groups.

CONCLUSION

Maternal first trimester serum leptin demonstrates a significant negative association with neonatal weight in preeclamptic pregnancies and to a lesser extent in normotensive pregnancies. A possible leptin's involvement in pathophysiological adaptations that define the foetal growth potential can be supported.

IGF-I, leptin and active ghrelin levels in very low birth weight infants during the first 8 weeks of life

AIM

We investigated the relationship between plasma insulin-like growth factor I (IGF-I), leptin, active ghrelin levels, and postnatal growth in very low birth weight (VLBW) infants.

METHOD

Plasma IGF-I, leptin, and active ghrelin levels were measured at birth and at 2, 4, 6 and 8 weeks after birth in 61 VLBW infants, including 31 appropriate-for-gestational-age (AGA) and 30 small-for-gestational-age (SGA) infants.

RESULTS

Insulin-like growth factor I levels were the lowest at birth, but increased gradually over the first 8 weeks of life. IGF-I was positively correlated with body weight, body length and body mass index at all time points. Leptin levels did not change over the study period. Ghrelin levels were significantly lower at birth; however, there were no significant differences between the levels after 2 weeks of age. Leptin and ghrelin levels were not correlated with anthropometrical measures. IGF-I levels at birth were significantly lower in SGA than in AGA infants, but the leptin and ghrelin levels were not significantly different between the two groups.

CONCLUSION

Insulin-like growth factor I is related to length and weight gain in the prenatal and the early postnatal periods in VLBW infants, but this does not appear to be the case for leptin and ghrelin.

Association of cord plasma leptin with birth size in term newborns

BACKGROUND

Leptin is secreted from adipose tissue and plays an important role in obesity. Recent studies have shown that the relationship between Leptin and body fat mass may have ethnic differences. The purpose of our study was to investigate the relationship between venous umbilical cord plasma Leptin and anthropometric markers in term healthy Taiwanese newborns.

METHODS

Umbilical venous plasma samples were obtained from 98 term neonates (48 males and 50 females) and leptin Levels were analyzed by enzyme-linked immunosorbent assay.

RESULTS

Umbilical cord plasma Levels of leptin were significantly higher in the female neonates than in males (p<0.001). The large-for-gestationaL age and appropriate-for-gestational age newborns had significantly higher Leptin cord plasma levels than the small-for-gestational age newborns (p<0.01 and p<0.05, respectively). In both male and female neonates, umbilical Leptin Levels showed significant positive correlations with birth weight and birth Length. Multiple Linear regression analysis revealed that birth weight was the only significant predictor of umbilical cord plasma Leptin levels in both male and female neonates. However, the slopes of the regressions between Leptin and birth weight in male and female neonates were not different.

CONCLUSION

In Taiwanese healthy term neonates, leptin umbilical cord plasma Levels are associated with sex and birth weight of the neonate. The relationship between Leptin and birth weight may differ among different ethnic groups. These findings imply that the relationship between leptin and body fat mass may develop early in life.

Association between serum adipocytokine and cholesterol levels in cord blood

BACKGROUND

Serum leptin and adiponectin levels are strongly associated with lipid metabolism in adults. These adipocytokines play a role in intrauterine and postnatal growth but the association between cord blood levels of these adipocytokines and cholesterol at birth remains unclear.

METHODS

The study involved 52 appropriate-for-gestational-age (AGA) infants (25 male, 27 female, 37-41 weeks of gestational age) born at Keiai Hospital without any maternal complications. Cord blood concentrations of leptin, total adiponectin, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), other neonatal characteristics, and maternal factors were assessed to investigate the association between cord blood leptin or adiponectin levels and cholesterol levels.

RESULTS

Cord blood leptin levels were significantly higher in girls. Simple regression analysis indicated that cord blood leptin levels were significantly associated with birthweight, gestational age, birthweight SD score, body mass index (BMI), ponderal index, LDL-C, and TC; but total adiponectin levels were not significantly associated with any neonatal characteristics or maternal factors. A multiple regression analysis indicated that cord leptin levels were significantly associated with BMI (beta= 0.407, P= 0.001), LDL-C (beta=-0.345, P= 0.004), and infant's gender (beta=-0.332, P= 0.006); adiponectin levels were significantly associated with only gestational age (beta= 0.279, P= 0.047).

CONCLUSION

Cord leptin level is significantly associated with cord cholesterol level at birth, anthropometry, and infant gender. The present study suggests that cord blood leptin may be a key hormone for controlling fetal lipid metabolism.

Adiponectin and leptin concentrations in dichorionic twins with discordant and concordant growth

CONTEXT

Discordant twin gestation, in which one fetus is growth restricted, is a unique model that can elucidate the mechanism(s) by which the intrauterine environment affects fetal growth.

OBJECTIVE

The objective of the study was to determine the cord blood adiponectin and leptin concentrations and evaluate their association with birth weight in dichorionic twins, with and without growth discordance. DESIGN, SETTING, PARTICIPANTS, AND MAIN OUTCOME MEASURE: In this cross-sectional study, arterial cord blood adiponectin and leptin concentrations were determined in two groups of newborns: 1) discordant twins, in which one of the twins is growth restricted (small for gestation age and abnormal umbilical arteries Doppler) and the other is appropriate for gestation age (AGA) (n = 14 pairs); and 2) concordant twins, in which both twins are AGA (n = 15 pairs).

RESULTS

Results were: 1) within the discordant twins group, the median adiponectin concentration was significantly lower in the growth-restricted newborns than in their cotwins (P = 0.004); 2) within the concordant twin group, there was no significant difference in the median cord blood adiponectin concentration between the two AGA twins; 3) the median leptin concentration did not differ between the twins pairs in both study groups; 4) a positive correlation between cord blood adiponectin concentrations and both birth weight (r = 0.7, P < 0.001) and gestational age (r = 0.6, P < 0.02) was found only in the small-for-gestational-age newborns; 5) linear regression model revealed that birth weight is independently associated with circulating adiponectin concentration.

CONCLUSIONS

Low circulating adiponectin concentrations, previously reported in adults, children, and infants who were born small for gestational age, characterize fetuses with growth restriction and are independently associated with birth weight.

Leptin resistance: a possible interface of inflammation and metabolism in obesity-related cardiovascular disease

Leptin is an adipocyte-derived hormone and cytokine that regulates energy balance through a wide range of functions, including several that are important to cardiovascular health. Increased circulating leptin, a marker of leptin resistance, is common in obesity and independently associated with insulin resistance and cardiovascular disease (CVD) in humans. The mechanisms of leptin resistance include genetic mutation, leptin self-regulation, limited tissue access, and cellular or circulating molecular regulation. Evidence suggests that central leptin resistance causes obesity and that obesity-induced leptin resistance injures numerous peripheral tissues, including liver, pancreas, platelets, vasculature, and myocardium. This metabolic- and inflammatory-mediated injury may result from either resistance to leptin's action in selective tissues, or excess leptin action from adiposity-associated hyperleptinemia. In this sense, the term "leptin resistance" encompasses a complex pathophysiological phenomenon. The leptin axis has functional interactions with elements of metabolism, such as insulin, and inflammation, including mediators of innate immunity, such as interleukin-6. Leptin is even purported to physically interact with C-reactive protein, resulting in leptin resistance, which is particularly intriguing, given C-reactive protein's well-studied relationship to cardiovascular disease. Given that plasma levels of leptin and inflammatory markers are correlated and also predict cardiovascular risk, it is conceivable that part of this risk may be mediated through leptin resistance-related insulin resistance, chronic inflammation, type II diabetes, hypertension, atherothrombosis, and myocardial injury. Leptin resistance and its interactions with metabolic and inflammatory factors, therefore, represent potential novel diagnostic and therapeutic targets in obesity-related cardiovascular disease.

Birth size and breast cancer risk: re-analysis of individual participant data from 32 studies

BACKGROUND

Birth size, perhaps a proxy for prenatal environment, might be a correlate of subsequent breast cancer risk, but findings from epidemiological studies have been inconsistent. We re-analysed individual participant data from published and unpublished studies to obtain more precise estimates of the magnitude and shape of the birth size-breast cancer association.

METHODS AND FINDINGS

Studies were identified through computer-assisted and manual searches, and personal communication with investigators. Individual participant data from 32 studies, comprising 22,058 breast cancer cases, were obtained. Random effect models were used, if appropriate, to combine study-specific estimates of effect. Birth weight was positively associated with breast cancer risk in studies based on birth records (pooled relative risk [RR] per one standard deviation [SD] [= 0.5 kg] increment in birth weight: 1.06; 95% confidence interval [CI] 1.02-1.09) and parental recall when the participants were children (1.02; 95% CI 0.99-1.05), but not in those based on adult self-reports, or maternal recall during the woman's adulthood (0.98; 95% CI 0.95-1.01) (p for heterogeneity between data sources = 0.003). Relative to women who weighed 3.000-3.499 kg, the risk was 0.96 (CI 0.80-1.16) in those who weighed < 2.500 kg, and 1.12 (95% CI 1.00-1.25) in those who weighed > or = 4.000 kg (p for linear trend = 0.001) in birth record data. Birth length and head circumference from birth records were also positively associated with breast cancer risk (pooled RR per one SD increment: 1.06 [95% CI 1.03-1.10] and 1.09 [95% CI 1.03-1.15], respectively). Simultaneous adjustment for these three birth size variables showed that length was the strongest independent predictor of risk. The birth size effects did not appear to be confounded or mediated by established breast cancer risk factors and were not modified by age or menopausal status. The cumulative incidence of breast cancer per 100 women by age 80 y in the study populations was estimated to be 10.0, 10.0, 10.4, and 11.5 in those who were, respectively, in the bottom, second, third, and top fourths of the birth length distribution.

CONCLUSIONS

This pooled analysis of individual participant data is consistent with birth size, and in particular birth length, being an independent correlate of breast cancer risk in adulthood.

Possible correlation of leptin with body fat distribution and adiposity: Evaluation of serum leptin in South Indian population

Background:  Leptin, an adipocyte-derived hormone, is known to play an important role in body fat. Gender, age, degree of obesity and sex steroids are expressed differentially in men and women. Methods:  We measured serum leptin, testosterone and β-estradiol concentration by radioimmunoassay in 300 subjects (60 normal weight, 60 underweight, 60 overweight, 60 obese and 60 morbidly obese) by age group (18-40 years and 41-62 years), using full-length recombinant human leptin as a standard. Results:  The present study found that morbidly obese and obese men and women older than 50 years had 50-70% higher body mass index (BMI)-adjusted leptin levels than younger subjects. In addition, obese and underweight subjects showed a tendency towards lower BMI-adjusted leptin levels in younger than older, in both men and women subjects. Multiple regression analysis showed that age was positively correlated with leptin in both genders, even if the slope of rise was twice as high in women than in men. Together, these results indicate that in both genders, most prominently in females, aging is associated with increased leptin production that is independent from the amount of fat and/or the role of sex hormones. Conclusion:  In conclusion, our data show that serum leptin concentrations in men and women gradually increase during aging, being higher in women than in men, but they are independent from BMI and other hormones. The inclusion of several hormones in our regression model showed that only testosterone in men, and estradiol and androstenedione in women were independent contributions to serum leptin levels, possibly accounting for part of the leptin sexual dimorphism in a south Indian population.

High leptin in pregnant mink (Mustela vison) may exert anorexigenic effects: a permissive factor for rapid increase in food intake during lactation

The role for leptin in food intake regulation in the mink, a polytocous seasonal breeder with altricial young, was investigated in pregnant and lactating dams and data were related to quantitative energy metabolism measurements and plasma concentrations of other important metabolic hormones. A total of nine mink dams were measured in consecutive 1-week balance periods, each including a 22h measurement of heat production by means of indirect calorimetry, and blood was sampled at weekly intervals throughout gestation and during lactation weeks 1–4. Intake of metabolisable energy (ME) was high and energy balance was positive until the first third of true gestation. During mid- and late gestation ME intake decreased (P<0·001) while heat production remained almost constant, resulting in negative energy balance and the loss of body weight. From late gestation until lactation week 4, ME intake increased by 3·5 times, but weight loss continued. Plasma concentrations of leptin were approximately doubled during the last two-thirds of true gestation (P<0·01), demonstrating a clear gestational hyperleptinaemia. Concentrations declined rapidly after parturition and then remained stable. Insulin was independent of leptin, with low concentrations coincident with hyperleptinaemia. Also, concentrations of thyroid hormones declined during gestation, probably reflecting the low food intake. Hyperleptinaemia concomitant with low ME intake, negative energy balance and mobilisation of body reserves suggested an anorexigenic effect of leptin in pregnant mink. This suppression of food intake in late gestation might be permissive for the rapid increase in food intake occurring after parturition.

Small for gestation and growth hormone therapy

3 to 10% of neonates are born small for gestation (SGA). This usually occurs because of intrauterine growth retardation (IUGR). After birth most SGA infants show good catch-up growth and normalize their height and weight. About 10% of them continue to remain short (<-2SD) and do not achieve normal adult height, resulting in psychosocial problems. The mechanism of short stature in these children is poorly understood. Infants who do not show catch-up growth usually have an alteration in the GH-IGF-I axis. Diagnostic and management criteria for short stature in SGA were ill-defined in the past. Growth hormone (GH) therapy for improving height in these children has been approved by the FDA. GH therapy leads to growth acceleration and normalization of height during childhood. Long term GH treatment normalizes adult height above -2 SDS in 85% children, and 98% achieve an adult height within their target height range. GH therapy is safe in SGA children, but it is important to monitor for side effects.

Cytokines and leptin correlation in patients with polycystic ovary syndrome: Biochemical evaluation in south Indian population

Background:  In polycystic ovary syndrome (PCOS), the leptin (OB protein) is related to reproductive function and inflammatory response. Leptin and cytokines have been thought to be putative local regulators in PCOS. Methods:  To examine the relationship between serum leptin and serum interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor-α (TNF-α) levels in underweight, overweight, obese and morbidly obese PCOS and non-PCOS subjects compared with normal weight, regularly menstruating women. Results:  Leptin levels are highly correlated with TNF-α, IL-6 and IL-8. There is a significant dependent increase with the degree of obesity, but in underweight PCOS subjects, leptin levels are elevated irrespective of the body mass index. Conclusion:  The present study showed that leptin levels were elevated in underweight and morbidly obese PCOS subjects. This could be the result of impaired expression of leptin in PCOS, leading to leptin resistance. As a result of this regulation, TNF-α, IL-6 and IL-8 were also elevated in morbidly obese and underweight PCOS subjects. In obese subjects, where there was an increase in adipose mass, increased levels of leptin were observed and this was attributed to the inflammatory properties while increasing the adipose mass. Serum IL-6 and IL-8 circulate at high levels and are more important systemically. They are, perhaps, the hormonal factors that induce leptin and insulin resistance in underweight PCOS subjects. Therefore, leptin and inflammatory markers were acting at paracrine and endocrine levels in PCOS subjects. (Reprod Med Biol 2005; 4: 247-254).

Interrelationships of maternal serum leptin, body mass index and gestational age

BACKGROUND

The aim of this study was to evaluate the interrelationships between maternal serum leptin level and body mass index (BMI) at different gestational ages or during the whole pregnancy.

METHODS

A total of 374 blood samples were obtained from 114 pregnant women when they visited the prenatal clinic for registration, Down syndrome screening test, 50 g oral glucose challenge test, hepatitis B markers test, and near or at the time of delivery. Serum leptin levels were measured by immunoradiometric assay. Linear regression analysis, 1-way ANOVA and post hoc tests were used to analyze the data.

RESULTS

Throughout the course of pregnancy, maternal serum leptin concentration was significantly correlated with gestational age (p = 0.001, r = 0.179). A good correlation was also found between gestational age and maternal serum leptin level in the second trimester (p = 0.021, r = 0.158). A significant decline in maternal serum leptin was found in the third trimester (p = 0.011, r = 0.237). There were good correlations between maternal leptin and BMI in all 3 trimesters (p = 0.002 in the first trimester, p < 0.001 in the second trimester, p = 0.007 in the third trimester) and through the whole pregnancy (p < 0.001). Maternal BMI was related to gestational age in the second trimester (p < 0.001) and the whole pregnancy (p < 0.001), but not in the first (p = 0.404) and third trimesters (p = 0.053).

CONCLUSION

Maternal serum leptin concentration was significantly related to gestational age (except in the first trimester) and BMI in the 3 trimesters and throughout pregnancy. Serum leptin concentration peaked during the early third trimester and declined significantly thereafter. Maternal BMI was related to gestational age in the second trimester and the whole pregnancy.

Neonatal leptin treatment reverses developmental programming

An adverse prenatal environment may induce long-term metabolic consequences, in particular obesity and insulin resistance. Although the mechanisms are unclear, this programming has generally been considered an irreversible change in developmental trajectory. Adult offspring of rats subjected to undernutrition during pregnancy develop obesity, hyperinsulinemia, and hyperleptinemia, especially in the presence of a high-fat diet. Reduced locomotor activity and hyperphagia contribute to the increased fat mass. Using this model of maternal undernutrition, we investigated the effects of neonatal leptin treatment on the metabolic phenotype of adult female offspring. Leptin treatment (rec-rat leptin, 2.5 microg/g.d, sc) from postnatal d 3-13 resulted in a transient slowing of neonatal weight gain, particularly in programmed offspring, and normalized caloric intake, locomotor activity, body weight, fat mass, and fasting plasma glucose, insulin, and leptin concentrations in programmed offspring in adult life in contrast to saline-treated offspring of undernourished mothers who developed all these features on a high-fat diet. Neonatal leptin had no demonstrable effects on the adult offspring of normally fed mothers. This study suggests that developmental metabolic programming is potentially reversible by an intervention late in the phase of developmental plasticity. The complete normalization of the programmed phenotype by neonatal leptin treatment implies that leptin has effects that reverse the prenatal adaptations resulting from relative fetal undernutrition.

Leptin, from fat to inflammation: old questions and new insights

Leptin is 16 kDa adipokine that links nutritional status with neuroendocrine and immune functions. Initially thought to be a satiety factor that regulates body weight by inhibiting food intake and stimulating energy expenditure, leptin is a pleiotropic hormone whose multiple effects include regulation of endocrine function, reproduction, and immunity. Leptin can be considered as a pro-inflammatory cytokine that belongs to the family of long-chain helical cytokines and has structural similarity with interleukin-6, prolactin, growth hormone, IL-12, IL-15, granulocyte colony-stimulating factor and oncostatin M. Because of its dual nature as a hormone and cytokine, leptin links the neuroendocrine and the immune system. The role of leptin in the modulation of immune response and inflammation has recently become increasingly evident. The increase in leptin production that occurs during infection and inflammation strongly suggests that leptin is a part of the cytokine network which governs the inflammatory-immune response and the host defense mechanisms. Leptin plays an important role in inflammatory processes involving T cells and has been reported to modulate T-helper cells activity in the cellular immune response. Several studies have implicated leptin in the pathogenesis of autoimmune inflammatory conditions, such as experimental autoimmune encephalomyelitis, type 1 diabetes, rheumatoid arthritis, and intestinal inflammation. Very recently, a key role for leptin in osteoarthritis has been demonstrated: leptin indeed exhibits, in concert with other pro-inflammatory cytokines, a detrimental effect on articular cartilage by promoting nitric oxide synthesis in chondrocytes. Here, we review the recent advances regarding leptin biology with a special focus on those actions relevant to the role of leptin in the pathophysiology of inflammatory processes and immune responses.

Body fat distribution and leptin correlation in women with polycystic ovary syndrome: Endocrine and biochemical evaluation in south Indian population

Aims:   Obesity is associated with the increased prevalence of infertility and is also an independent risk factor in women with polycystic ovary syndrome (PCOS). The aim of this study was to examine the extent to which the ob gene product, leptin, alone or in combination with other metabolic and endocrinal parameters, may be correlated to infertility with the incidence of PCOS. Methods:  Serum leptin levels were measured in both PCOS and non-PCOS subjects of the following categories, such as thin, overweight, obese and morbidly obese, and compared with normal weight women. Female infertility is associated with body mass index, percentage of body fat, body fat distribution, and other biochemical and endocrinal parameters parameters. Results:  Women with PCOS and normally menstruating control women were analyzed by univariate analysis for body fat distribution. Serum leptin was positively correlated with body mass index, percentage of body fat, serum levels of dehydroepiandrosterone sulfate, testosterone, free testosterone, luteinizing hormone and prolactin. Serum leptin was inversely correlated with serum sex hormone-binding globulin concentration and androstenedione. Conclusions:  We report, for the first time in the Indian population, that leptin levels are different in thin and morbidly obese PCOS patients than in regularly menstruating normal weight subjects, and leptin could be a novel, independent risk factor for PCOS. (Reprod Med Biol 2005; 4: 71-78).

Body fat distribution and leptin correlation in women with polycystic ovary syndrome: Endocrine and biochemical evaluation in south Indian population

Aims:   Obesity is associated with the increased prevalence of infertility and is also an independent risk factor in women with polycystic ovary syndrome (PCOS). The aim of this study was to examine the extent to which the ob gene product, leptin, alone or in combination with other metabolic and endocrinal parameters, may be correlated to infertility with the incidence of PCOS. Methods:  Serum leptin levels were measured in both PCOS and non-PCOS subjects of the following categories, such as thin, overweight, obese and morbidly obese, and compared with normal weight women. Female infertility is associated with body mass index, percentage of body fat, body fat distribution, and other biochemical and endocrinal parameters parameters. Results:  Women with PCOS and normally menstruating control women were analyzed by univariate analysis for body fat distribution. Serum leptin was positively correlated with body mass index, percentage of body fat, serum levels of dehydroepiandrosterone sulfate, testosterone, free testosterone, luteinizing hormone and prolactin. Serum leptin was inversely correlated with serum sex hormone-binding globulin concentration and androstenedione. Conclusions:  We report, for the first time in the Indian population, that leptin levels are different in thin and morbidly obese PCOS patients than in regularly menstruating normal weight subjects, and leptin could be a novel, independent risk factor for PCOS. (Reprod Med Biol 2005; 4: 71-78).

Developmental changes in leptin as a measure of energy status in human infants in a natural ecologic setting

BACKGROUND

Most human research on leptin has involved well-nourished subjects or clinical states such as anorexia nervosa or cancer cachexia.

OBJECTIVE

We studied the development of leptin as a monitor of energy status in young African infants whose growth patterns probably reflect the evolutionary norm.

DESIGN

We enrolled a prospective birth cohort of 138 rural Gambian mother-infant pairs. Plasma leptin was analyzed in maternal blood in late pregnancy, in cord blood, and at 8, 16, and 52 wk in the infants. Body mass index (BMI; in kg/m2) was used as a proxy for fatness. The mothers were lean (BMI: 21.6+/-2.5), and the infants grew poorly compared with Western standards (average weight-for-age z score of -1.9 at 52 wk).

RESULTS

Maternal and cord blood leptin and birth weight were all positively correlated. Throughout infancy, leptin was highly correlated with BMI. A strong sex difference existed at birth (ie, leptin concentrations were significantly higher in females than in males), disappeared at 8 wk, and reappeared at 16 and 52 wk. Absolute leptin concentrations declined by almost 90% from birth to 52 wk, but leptin's ability to discriminate across a range of BMI values improved with age. In early infancy, leptin concentrations were uncorrelated with recent changes in BMI, but, by 52 wk, leptin was able to assess both the size of energy stores and the direction of recent changes.

CONCLUSIONS

Leptin concentrations signal energy status from fetal life onward. As infancy progresses, leptin's power to discriminate both chronic and dynamic energy status increases, and this discrimination is achieved at much lower circulating peptide concentrations.

Leptin stimulates the activity of the system A amino acid transporter in human placental villous fragments

The activity and expression of placental nutrient transporters are primary determinants for the supply of nutrients to the fetus, and these nutrients in turn regulate fetal growth. We developed an experimental system to assess amino acid uptake in single primary villous fragments to study hormonal regulation of the amino acid transporter system A in term human placenta. Validation of the method, using electron microscopy and studies of hormone production, indicated that fragments maintained ultrastructural and functional integrity for at least 3 h. The activity of system A was measured as the Na(+)-dependent uptake of methylaminoisobutyric acid (MeAIB), and the effect of 1 h incubation in various hormones was investigated. Uptake of MeAIB into villous fragments in the presence of Na(+) was linear up to at least 30 min. Insulin (300 ng/ml, n = 14) increased system A activity by 56% (P < 0.05). This effect was also present at insulin concentrations in the physiological range (+47% at 0.6 ng/ml, n = 10, P < 0.05). Leptin (500 ng/ml, n = 14) increased Na(+)-dependent MeAIB uptake by 37% (P < 0.05). System A activity increased in a concentration-dependent fashion in response to leptin (n = 10). However, neither epidermal GF (600 ng/ml), cortisol (340 ng/ml), nor GH (500 ng/ml) altered system A activity significantly (n = 14). We conclude that primary single isolated villous fragments can be used in studies of hormonal regulation of nutrient uptake into the syncytiotrophoblast. These data suggest that leptin regulates system A, a key amino acid transporter.

Leptin: a review of its peripheral actions and interactions

Following the discovery of leptin in 1994, the scientific and clinical communities have held great hope that manipulation of the leptin axis may lead to the successful treatment of obesity. This hope is not yet dashed; however the role of the leptin axis is now being shown to be ever more complex than was first envisaged. It is now well established that leptin interacts with pathways in the central nervous system and through direct peripheral mechanisms. In this review, we consider the tissues in which leptin is synthesized and the mechanisms which mediate leptin synthesis, the structure of leptin and the knowledge gained from cloning leptin genes in aiding our understanding of the role of leptin in the periphery. The discoveries of expression of leptin receptor isotypes in a wide range of tissues in the body have encouraged investigation of leptin interactions in the periphery. Many of these interactions appear to be direct, however many are also centrally mediated. Discovery of the relative importance of the centrally mediated and peripheral interactions of leptin under different physiological states and the variations between species is beginning to show the complexity of the leptin axis. Leptin appears to have a range of roles as a growth factor in a range of cell types: as be a mediator of energy expenditure; as a permissive factor for puberty; as a signal of metabolic status and modulation between the foetus and the maternal metabolism; and perhaps importantly in all of these interactions, to also interact with other hormonal mediators and regulators of energy status and metabolism such as insulin, glucagon, the insulin-like growth factors, growth hormone and glucocorticoids. Surely, more interactions are yet to be discovered. Leptin appears to act as an endocrine and a paracrine factor and perhaps also as an autocrine factor. Although the complexity of the leptin axis indicates that it is unlikely that effective treatments for obesity will be simply derived, our improving knowledge and understanding of these complex interactions may point the way to the underlying physiology which predisposes some individuals to apparently unregulated weight gain.

Serum leptin in disabled and non-disabled children in an Indian slum population

OBJECTIVE

To assess the concentration of serum leptin in a population of malnourished children and to compare the leptin levels of disabled and non-disabled children in this population.

DESIGN

Case-control study.

SUBJECTS

Eighty-one children, comprising 41 children with mixed disabilities and 40 non-disabled controls, were selected from 425 children involved in a case-control study assessing the nutritional status of children with disabilities in an Indian slum population.

METHODS

Leptin was measured in the serum samples and was compared with anthropometry (weight-for-age Z-scores (WAZ), height-for-age Z-scores (HAZ), weight-for-height Z-scores (WHZ), body mass index (BMI), mid-upper-arm circumference (MUAC), sub-scapular skinfold thickness and triceps skinfold thickness) and serum acute phase proteins.

RESULTS

The children were very malnourished with WAZ=-2.07 (s.d. 1.15), HAZ=-2.15 (s.d. 1.85) and WHZ=-1.07 (s.d. 0.83). Leptin was extremely low in both the disabled (1.44 ng/ml; 95% confidence interval, CI, 1.23-1.69) and the non-disabled (1.19 ng/ml; 95% CI 1.04-1.35) children. There were no differences between the disabled and non-disabled groups as a whole but 15 children with neurological disabilities had significantly higher (P<0.05) serum leptin (1.65 ng/ml; 95% CI 1.29-2.06) than the non-disabled children. Girls (1.55 ng/ml; 95% CI 1.29-1.87) had significantly higher concentrations of leptin than boys (1.11 ng/ml; 95% CI 1.02-1.22; P=0.002). Leptin did not correlate with any biochemical or anthropometric measures.

CONCLUSIONS

In this population, where malnutrition was common, serum leptin levels were very low and did not correlate with anthropometry.

SPONSORSHIP

UK Department for International Development; Virgin Airways through the Great Ormond Street Hospital Trustees.

Is leptin the link between fat and bone mass?

Recently, leptin has emerged as a potential candidate responsible for protective effects of fat on bone tissue. However, it remains difficult to draw a clear picture of leptin effects on bone metabolism because published data are sometimes conflicting or apparently contradictory. Beyond differences in models or experimental procedures, it is tempting to hypothesize that leptin exerts dual effects depending on bone tissue, skeletal maturity, and/or signaling pathway. Early in life, leptin could stimulate bone growth and bone size through direct angiogenic and osteogenic effects on stromal precursor cells. Later, it may decrease bone remodeling in the mature skeleton, when trabecular bone turnover is high, by stimulating osteoprotegerin (OPG) expression. Leptin negative effects on bone formation effected through central nervous system pathway could counterbalance these peripheral and positive effects, the latter being predominant when the blood-brain barrier permeability decreases or the serum leptin level rises above a certain threshold. Thus, the sex-dependent specificity of the relationship between leptin and bone mineral density (BMD) in human studies could be, at least in part, caused by serum leptin levels that are two- to threefold higher in women than in men, independent of adiposity. Although these hypotheses remain highly speculative and require further investigations, existing studies consistently support the role of leptin as a link between fat and bone.

Spatial and developmental regulation of leptin in fetal sheep

To better understand the biology of leptin during prenatal life, the developmental and spatial regulation of leptin was studied in ovine fetuses. Fetal plasma leptin increased steadily between days 40 and 143 postcoitus (PC), but it was unrelated to fetal weight or placental weight at day 135 PC. Leptin gene expression was detected in fetal brain and liver during most of gestation and in fetal adipose tissue after day 100 PC. At day 130 PC, expression in fetal perirenal adipose tissue was approximately 10% of maternal expression. In contrast, leptin gene expression was never detected in the placenta and other uteroplacental tissues. When ewes were fed 55% of requirements between days 122 and 135 PC, fetal plasma leptin remained constant despite acute reduction in maternal concentration. We conclude that fetal plasma leptin originates mostly from nonadipose tissue in early pregnancy and, in addition, from fetal adipose tissue near term. The role of fetal plasma leptin remains uncertain given the lack of nutritional regulation and association with fetal growth.

Prospective function of placental leptin at maternal-fetal interface

Leptin is an endocrine and a growth factor which is important for regulation of body fat, feeding, and energy homeostasis. The anti-obesity function of leptin has been recently extended to reproduction, puberty and pregnancy as an endocrine signal to the hypothalamus. Leptin controls the functional integrity of the feto-placental unit thereby maintaining pregnancy by virtue of its immunomodulatory property via T lymphocytes or other proto-oncogenes. Dysregulation of autocrine/paracrine function of leptin at feto-placento-maternal interface may be implicated in the pathogenesis of recurrent miscarriage gestational diabetes, pre-eclampsia and intra-uterine fetal growth retardation including disturbance of fetal bone turnover. This review will focus on the role of leptin in normal and abnormal pregnancy and fetal growth.

Postnatal changes in concentrations of free and bound leptin

AIM

To evaluate the effect of maternal diabetes on the concentrations of free and bound leptin at birth and during postnatal adaptation.

METHODS

Total, bound, and free leptin concentrations and the percentage of free leptin were measured in cord plasma and plasma at 3 days of age of 13 term infants of mothers with gestational diabetes mellitus (GDM) and 13 term infants of healthy mothers. Gestational age was 40.2 (1.4) weeks, and birth weight was 3693 (549) g (means (SD)).

RESULTS

At birth, infants of mothers with GDM had significantly higher concentrations of total, bound, and free leptin and a higher percentage of free leptin (all p < 0.05). In all infants, these concentrations were significantly lower at 3 days of age than at birth (all p < 0.003), and the differences in concentrations of total, bound, and free leptin between the two groups were no longer significant. In infants of mothers with GDM, the percentage of free leptin remained unchanged, and was higher (p<0.05) than in infants of healthy mothers; in the latter group the percentage of free leptin significantly declined (p = 0.02).

CONCLUSIONS

GDM appears to influence fetoplacental leptin metabolism. This effect may be mediated through altered maternal glucose metabolism, or insulinaemia, or both.

A heliocentric view of leptin

Leptin is significantly broadening our understanding of the mechanisms underlying neuroendocrine function. Initially, based on a rather static view of the hormone, most investigations focused on the effects of leptin on food intake control and body-weight homeostasis, with attention primarily focused on the implications of leptin as a lipostatic factor and central satiety agent. However, the almost ubiquitous distribution of leptin receptors in peripheral tissues provided a fertile area for investigation and a more dynamic view of leptin started to unfold. This adipocyte-derived circulating peptidic hormone, with a tertiary structure resembling that of members of the long-chain helical cytokine family, has generated an enormous interest in the interaction as well as integration between brain targets and peripheral signals. Considerable evidence for systemic effects of leptin on specific tissues and metabolic pathways indicates that leptin operates both directly and indirectly to orchestrate complex pathophysiological processes. Disentangling the biochemical and molecular mechanisms in which leptin is involved represents one of the major challenges ahead.