Leptin receptor in human term placenta: in situ hybridization and immunohistochemical localization

In the present study, we investigated the expression and localization of le ptin receptors in human term placentae. On human term placenta tissue slice s, digoxigenin-UTP labelled RNA-probe detected the long form of the leptin receptor ObR(L) mRNA in syncytiotrophoblasts of the villi, whereas the haem atological subtype of the leptin receptor ObR/B219.1 was detected in blood cells of the intervillous space and fetal vessels. Immunohistochemistry, wi th two polyclonal antibodies to the N-terminus recognizing ObR(L) and ObR(S ) of the leptin receptors and one to the C-terminus recognizing the long fo rm of the leptin receptor ObR(L), localized leptin receptor protein at the apical membrane of the syncytiotrophoblasts. Our results show that the long form of the leptin receptor ObR(L) is expressed in human term placentae. W e localized the long form of leptin receptor mRNA to the cytoplasm of syncy tiotrophoblasts and leptin receptor proteins in human term placentae to the apical membrane of syncytiotrophoblasts. We conclude that in term placenta e, leptin could mediate a growth promoting effect in the fetoplacental unit through the long form of the leptin receptor localized in the syncytiotrop hoblasts. In contrast, the haematological subtype of the leptin receptor is not expressed in placental cells, but solely by blood cells; in the interv illous space and fetal vessels. (C) 1999 Harcourt Publishers Ltd.