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

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.

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.

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.

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.