Maria Francesca Fissore

Ghrelin, leptin and IGF-I levels in breast-fed and formula-fed infants in the first years of life.

Aim: To establish ghrelin, leptin and IGF‐I serum levels in breastfed (BF) and formula‐fed (FF) infants during the first period of life. Methods: A cross‐sectional study was conducted on fasting blood venous samples obtained from exclusively BF (n=106) and FF (n=100) infants to measure total ghrelin (RIA test), leptin (RIA test) and IGF‐I (chemiluminescence). Anthropometrical measurements of weight, length and cranial circumference were performed. Results: During the first 4 mo of life, FF infants compared to BF ones showed higher ghrelin levels (2654.86 vs 2132.96 pg/ml; p<0.032), higher IGF‐I levels (3.73 vs 3.15 ng/ml; p=0.00) and lower leptin levels (0.68 vs 1.16 ng/ml; p<0.04). Leptin values were higher in females than in males (0.80 vs 0.47 ng/ml; p<0.03), while no gender‐related difference was found for ghrelin and IGF‐I. No differences were found in anthropometrical measurements comparing the two groups of infants. A multiple regression analysis showed an inverse correlation between ghrelin and leptin values (p<0.04) and between IGF‐I and leptin levels (p=0.00).

Serum ghrelin concentration and weight gain in healthy term infants in the first year of life.

Objectives: Ghrelin, a recently discovered hormone mainly secreted by the stomach, has several metabolic functions including regulation of food intake, energy homeostasis and body weight. There are few studies on this hormone in healthy infants during the first year of life. The aim of this study was to examine the correlations between ghrelin and weight gain in healthy term infants in the first year of life. Methods: 104 healthy term infants aged 0 to 12 months were included in a cross-sectional study. Anthropometric measurements were assessed and mean weight gain was calculated. Serum ghrelin concentrations have been determined at least 3 hours after feeding by radioimmunoassay test. Results: Ghrelin concentrations were correlated negatively to weight gain (r = −0.302; P = 0.003) and positively to age (r = 0.412; P < 0.001), weight (r = 0.374; P < 0.001) and length (r = 0.387; P < 0.001). In breastfed infants a statistically significant negative correlation between ghrelin concentration and infant weight gain (r = −0.407; P = 0.001) was observed, whereas in formula-fed infants this correlation was not statistically significant (r = −0.067; P = 0.719). Conclusions: The negative correlation observed between ghrelin concentration and infant weight gain suggests that ghrelin might also play a role in the regulation of body weight in healthy infants with a physiologic energy balance. Further studies are needed to clarify how ghrelin might be involved in both short-term and long-term energy balance.

Evaluation of leptin in breast milk, lactating mothers and their infants

Background/Objectives:Leptin is present in human milk, but it is not clear what the relationship between breast milk (BM) leptin levels and maternal and infant serum leptin concentrations is. The objective of this study was to evaluate the leptin concentration in BM and to investigate its relationship with infants’ and mothers’ anthropometric parameters and with serum leptin concentration in breast-fed (BF) infants and lactating mothers.Subjects/Methods:We enrolled 36 adequate for gestational age healthy, exclusively BF, term infants aged <6 months. Leptin concentration in serum and BM was determined by radioimmunoassay (RIA) test (human-leptin-RIA-sensitive, Mediagnost). Infants’ and mothers’ weights, lengths and body mass indexes (BMI) were measured.Results:The median leptin concentration was 3.42 ng/ml (interquartile range (IR): 2.65) in BF infants’ serum, 3.02 ng/ml (IR: 2.85) in mothers’ serum (n=17) and 0.51 ng/ml (IR: 0.34) in BM (n=24). BM leptin concentrations were significantly lower than serum BF infant (P<0.001) and maternal (P<0.001) leptin levels. Infant serum leptin concentration correlated positively with infant weight (r=0.437, P=0.008) and BMI (r=0.561, P=0.004). Mother serum leptin levels correlated positively with weight (r=0.755, P<0.001) and BMI (r=0.661, P=0.007). No correlations were found between BM leptin and serum leptin concentrations in BF infants and mothers.Conclusions:We confirmed the presence of leptin in BM at a lower concentration than that found in infant and lactating mother serum. We observed a positive correlation between serum leptin levels in BF infants and their growth parameters.

Looking for a relation between serum leptin concentration and body composition parameters in healthy term infants in the first 6 months of life.

We carried out a cross-sectional study of 115 healthy infants, younger than 6 months old, exclusively breast-fed or formula-fed, to investigate correlations between circulating leptin concentrations and body composition measurements. Serum leptin was evaluated with radioimmunoassay, and body composition with bioelectrical impedance analysis. Multiple regression analysis showed a relationship between serum leptin and body mass index in the entire study population (P = 0.042). There was a significant negative relationship between serum leptin and phase angle (P = 0.006) in formula-fed infants. Serum leptin was positively related to subscapular skinfold thickness (P = 0.055) and negatively to reactance (P = 0.057) only in formula-fed infants, although the differences were just below significance. Serum leptin concentration was higher in breast-fed infants (P = 0.002), and was not correlated with body composition parameters. This study indicates that there is a relation between leptin and infant body composition in the first months of life, although the link needs to be explored further.

Breast Milk Hormones and Regulation of Glucose Homeostasis

Growing evidence suggests that a complex relationship exists between the central nervous system and peripheral organs involved in energy homeostasis. It consists in the balance between food intake and energy expenditure and includes the regulation of nutrient levels in storage organs, as well as in blood, in particular blood glucose. Therefore, food intake, energy expenditure, and glucose homeostasis are strictly connected to each other. Several hormones, such as leptin, adiponectin, resistin, and ghrelin, are involved in this complex regulation. These hormones play a role in the regulation of glucose metabolism and are involved in the development of obesity, diabetes, and metabolic syndrome. Recently, their presence in breast milk has been detected, suggesting that they may be involved in the regulation of growth in early infancy and could influence the programming of energy balance later in life. This paper focuses on hormones present in breast milk and their role in glucose homeostasis.

Leptin levels in breast-fed infants

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Serum ghrelin concentration, fasting time and feeding in infants.

BACKGROUND Data on hormonal feeding control in infants in the first months of life according to the kind of feeding are scanty. AIM To evaluate whether serum ghrelin could be involved in feeding behaviour control of breast-fed (BF) and formula fed (FF) infants. METHODS We studied 50 AGA healthy term infants aged 1-6 months of age. Serum ghrelin concentration was determined by RIA. Fasting time (measured as the difference between the time of the last meal and the time of blood collection) and number of meals were recorded. RESULTS A positive correlation between serum ghrelin levels and fasting time emerged in FF infants (r = 0.752; p <0.001) but not in BF infants (r = 0.345; p = 0.072). CONCLUSIONS Circulating ghrelin concentration correlates positively with fasting time in FF infants; these infants have higher serum ghrelin concentration, longer fasting time and fewer meals than BF infants. These observations suggest a possible influence of early feeding on mechanisms regulating satiety and feeding behaviour.

Leptin in Breast-Fed and Formula-Fed Infants

Introduction: Leptin is a hormone present in breast milk, but not in formula, which regulates food intake and energy metabolism; it could be one of the factors involved in preventing obesity. Breast milk leptin provides a physiologic explanation for some of the advantages seen in normal growth, regulation of energy intake and immunological status in breast-fed (BF) compared with formula-fed (FF) infants. Aim: To see whether leptin levels are different in BF or FF infants in the first months of life. Methods: We studied 186 AGA healthy infants, in the first 22 m, without any disease of the gastrointestinal tract, admitted to our Department during the period between June 2000 and August 2003. Serum leptin concentration was determined at least 3 h post-feeding by RIA test (LEP-R44 Mediagnostic, Reutlingen, Germany). For each infant the parents filled up a form for the Ethical Committee. Statistical Analysis: Student t-test was performed. Statistical significance was set at p<0.05. Data have been normalized with natural logarithm. Results: A significant difference (p=0.044) appeared in the first 4 m (n=82) between breast-fed (BF) (1.16 ± 0.99 ng/ml) and formula-fed (FF) (0.68 ± 1.11 ng/ml) infants. Between 4 and 8 m of age there were no differences in leptin levels between feeding groups (BF (n=21): 0.73 ± 1.03 ng/ml; FF (n=15): 0.55 ± 0.84 ng/ml). Similar results have been found in infants between 8 and 12 m (n=32; BF: 0.27 ± 1.01 ng/ml; FF: 0.71 ± 0.87 ng/ml). Conclusions: Published data show that leptin levels are higher in breast-fed infants than in formula-fed ones. Breast-fed infants feed more frequently and take in less per feed compared with formula-fed infants. The presence of leptin in breast milk may have a positive effect on satiety and regulation of energy intake. The long-term consequences of this difference between BF and FF infants and the role of leptin in promoting later obesity are unknown.