Objective:To investigate whether placental tissues produce leptin and determine the relationship between expression levels of leptin-mRNA in placenta and fetal growth and development.Methods:52 neonates were divided into 3 subgroups:(1)birth weight large for gestational age (LGA)( n =14)

(2)birth weight appropriate for gestational age (AGA)( n =21)

(3)birth weight small for gestational age (SGA)( n =17).Reverse transcription-polymerase chain reaction(RT-PCR) technique was used to detect human leptin-mRNA derived from placental-RNA.The expression levels of leptin-mRNA were quantitated using fluorescence intensity analysis.The correlations of expression level of placental leptin-mRNA with placental weight

birth weight

newborn Ponderal index(PI)

maternal weight

maternal body mass index(BMI) and gender were studied.Results:The expression levels of placental leptin-mRNA in LGA infants(119.7±13.0) and SGA infants(76.8±15.1) were significantly higher and lower respectively than those in the AGA infants(94.4±17.4)( P <0.001 and 0.005).The significant positive correlations were observed between the leptin-mRNA expression in placenta and placental weight( r =0.54)

birth weight ( r =0.59) and Ponderal index( r =0.56).There were no correlations between the expression levels of placental leptin-mRNA and maternal weight ( r = 0.21) and maternal BMI ( r = 0.18).The difference in placental leptin-mRNA expression between female and male neonates was statistically not significant.Conclusions:The placenta is one of the major sources of leptin in the fetal circulation.We suggest that there are strong associations between the expression levels of placental leptin-mRNA and fetal growth.Placental leptin may play an important role in fetal growth as a regulator.Gender differences are not found in placental leptin-mRNA expression.