Differential Expression of Leptin and Leptin Receptor mRNA in Obese and Non-Obese Women across the Menstrual Cycle Title

Abstract

OBJECTIVE: The aim of this study was to investigate the messenger ribonucleic acid expression of leptin (L-mRNA) and the leptin receptor (OB-RmRNA) in subcutaneous fat tissue and to determine their relationship with leptin and testosterone and steroid serum levels over the course of the menstrual cycle (MC), in obese (OBW) and non-obese women (NOW). DESIGN: Observational study investigating mRNA transcript expression of leptin and the leptin receptor from human subcutaneous fat specimens, as well as leptin serum levels, both in relation to the testosterone and sex hormones during the MC in obese and non-obese women. METHODS: Nineteen women, thirteen with a body mass index (BMI) > 25 Kg/m 2 and 6 with BMI < 25 Kg/m 2 were included. RT-PCR was used to detect L-mRNA transcripts of leptin and its receptor in samples from 28 fat biopsies taken from seven volunteers (20 from OW and 8 from NOW). The serum concentrations of leptin and steroid hormones were measured throughout the MC using radioinmuno analysis. RESULTS: The percentages of women expressing leptin L-mRNA during the phases of the MC were: early follicular (EF), 14.3%; late follicular (LF), 28.6%; early luteal (EL), 14.3%; and late luteal (LL), 42.9%. The percentages of OB-RmRNA were: EF, 71.4%; LF, 14.3%; EL, 28.6%; and LL, 71.4%. Leptin serum levels were directly related to BMI (p < 0.001), and testosterone (p < 0.001) and indirectly to SHBG (p < 0.001). CONCLUSION: The L-mRNA expression and its receptor in subcutaneous human tissue are regulated throughout the MC in a periodic manner. The physiological role of testosterone in regulation of expression L-mRNA and OB-RmRNA during the secretory phase of the MC in obese women requires further investigation.