ABSTRACT
OBJECTIVE: To investigate if the vasoactive systems adrenomedullin (ADM) and endothelin-1 (ET-1) are expressed in human adipose tissues in children and in adults and to determine the distribution pattern of nitric oxide synthases (NOS). DESIGN AND SUBJECTS: Subcutaneous, mesenterial and omental adipose tissue specimens taken from 15 children (age 0.5-16 y, median 6 y) and 13 adults (age 43-79 y, median 60 y) were analyzed. The body mass indices (BMI) were within the normal range. All patients were normotensive, and were free of infectious disease, and metabolic or endocrine disorders. The specimens were taken during elective laparotomies after informed consent was obtained. MEASUREMENTS: ADM, ET-1, the endothelial (eNOS) and inducible (iNOS) NOS as well as two housekeeping genes were measured using quantitative real-time PCR. RESULTS: ADM gene expression was found at all locations, and was significantly higher in adults than in children (P<0.01 for subcutaneous and omental adipose tissue). ET-1 mRNA was distributed in a similar way, showing significantly higher levels in the subcutaneous and mesenterial adipose tissue sections of adults than of children. For eNOS, the adult patients exhibited a higher expression in subcutaneous and mesenterial specimens than the children (P<0.01 and P<0.05). The iNOS mRNA was increased in subcutaneous, mesenterial and omental adipose tissues in the adult cohort compared to the children's levels (P<0.05 to P<0.01). CONCLUSION: Human adipose tissue expresses many vasoactive substances including ADM and ET-1. In adults, the amounts of ET-1 and ADM as well as eNOS and iNOS mRNA are higher, possibly due to a physiological upregulation with increasing age. Although there are differences depending on the locations of the tissues, the expression patterns of the antagonists ADM and ET-1 are quite similar, indicative of a well-balanced pattern of local gene expression in normotensive individuals with normal body weight.
Subject(s)
Adipose Tissue/metabolism , Aging/metabolism , Endothelin-1/metabolism , Peptides/metabolism , Adolescent , Adrenomedullin , Adult , Aged , Body Mass Index , Child , Child, Preschool , Endothelin-1/genetics , Female , Gene Expression Regulation, Developmental , Humans , Infant , Male , Mesentery/metabolism , Middle Aged , Nitric Oxide Synthase/genetics , Nitric Oxide Synthase/metabolism , Nitric Oxide Synthase Type II , Nitric Oxide Synthase Type III , Omentum/metabolism , Peptides/genetics , RNA, Messenger/genetics , Subcutaneous Tissue/metabolismABSTRACT
OBJECTIVE: Adipose tissue displays depot-specific metabolic properties and a predominant gene expression of leptin in subcutaneous tissue. The aim of the study was to evaluate leptin mRNA expression in various adipose tissues and to relate it to plasma leptin concentrations. Furthermore, developmental changes in leptin gene expression from childhood to adulthood were examined. DESIGN AND METHODS: Thoracic subcutaneous and intrathoracic adipose tissue specimens were obtained in 22 adults (51-81 years) and 23 children (0.1-17 years) undergoing cardiac surgery, and abdominal subcutaneous, omental and mesenterial fat specimens were collected from 21 adults (38-79 years) and 22 children (0.2-17 years) before abdominal surgery. Preoperative plasma leptin concentrations were measured by RIA. Leptin mRNA expression was quantified by TaqMan real-time PCR. RESULTS: In adults, there was no difference between leptin gene expression in subcutaneous and intrathoracic fat, whereas in children leptin mRNA expression was significantly higher in subcutaneous adipose tissue. In omental fat, leptin mRNA levels were significantly lower compared with subcutaneous and mesenterial sites in both children and adults. Adults revealed a significantly higher leptin gene expression in subcutaneous, omental and mesenterial adipose tissues than children. Subcutaneous and omental leptin gene expression are independent factors for plasma leptin concentrations in children and adults. CONCLUSION: Leptin is differentially expressed at different adipose tissue sites, a situation which is even more pronounced in children. There is a developmental increase in leptin mRNA expression in adipose tissue during childhood, reaching maximal capacity in adulthood.
