Expression of leptin receptor in human endometrium and fluctuation during the menstrual cycle

Leptin is secreted by adipocytes and regulates appetite through interaction with hypothalamic leptin receptors (OB-R). Accumulated evidence shows that leptin is involved in the stimulation of reproductive functions and that l ocal expression of leptin and OB-R in the ovary, oocyte, embryo, and placen ta plays a role in early development. To investigate the role of leptin in implantation, we examined the expression of OB-R and leptin in the human en dometrium. Northern and Western blot analyses and RT-PCR showed that the lo ng form of OB-R (OB-R,) messenger ribonucleic acid (mRNA) and protein were expressed. In contrast, leptin mRNA or protein was not detected. All of the splice variants of OB-R (OB-R,) and OB-R-L transcripts were expressed in 9 0% and 84% of the cases, respectively. OB-R mRNA expression peaked in the e arly secretory phase. Decidual tissue of early gestation also expressed OB- R-T and OB-R-L. Their incidence and abundance were comparable among endomet ria with benign uterine diseases and disease-free endometria and were not r elated to a body mass index within the normal range. The present results in dicate that OB-R, but not leptin, is expressed in the human endometrium.