Leptin correlates with the skinfold thickness in prepubertal and pubertal girls

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.

Leptin gene expression in subcutaneous adipose tissue in girls before and during puberty

OBJECTIVES

Leptin functions as a neuroendocrine hormone and it is related to the onset of puberty in animal models. Its role in normal human sexual maturation is still incompletely defined. The aim of the study was to assess the relationships between leptin mRNA (gene) expression, thickness of subcutaneous fat tissue and the serum concentration of leptin in girls before and during puberty.

STUDY DESIGN

Twenty-nine lean girls were studied (mean age 10.8+/-1.9 years). The subjects were divided into two groups according to pubertal status. The first group consisted of 14 prepubertal girls and second group of 15 girls who were in puberty. Body height, weight, arm circumference, skin fold thickness at abdominal, triceps and subscapular sites were measured. Serum leptin was assessed by RIA method. Leptin mRNA was measured in subcutaneous abdominal adipose tissue by semi-quantitative assays based on reverse transcription (RT) of the mRNA and polymerase chain reaction (PCR) amplification of the cDNA.

RESULTS

Girls in pubertal stages had higher serum leptin concentration than prepubertal girls. The mean values of leptin mRNA level in subcutaneous abdominal adipose tissue were not statistically different between groups. There was also no difference between the thickness of skin folds in investigated girls. A positive correlation between leptin mRNA expression and skin fold thickness, BMI and arm circumference as well as between the leptin concentration and skin fold thickness, BMI and arm circumference were observed.

CONCLUSIONS

The level of leptin gene expression and serum leptin concentrations depend on the amount of fat tissue. We can propose that initiation of pubertal events does not result from increased of leptin mRNA expression in subcutaneous abdominal fat cells or from its increased concentration in blood.