Immunolocalization of leptin and its receptor in the placenta of cats

The aim of the present study was to investigate the presence and the distribution of leptin (Ob) and its receptor (ObR) in the feline placenta at term by means of immunohistochemical techniques. A few Ob-positive cells were observed scattered in the lamellae of the labyrinthine placenta. These cells had the morphological characteristics typical of the very abundant cells in the placenta of cats that can be considered as being decidual and, in some cases, syncytiotrophoblastic cells. A few ObR-positive cells were observed in the same placental portion and were mainly localized in the lamellae, showing morphological features typical of decidual and syncytiotrophoblastic cells. No other structure of the placenta or the uterine wall showed positive reaction to the antibodies used. Our results confirm what has already been demonstrated in humans and laboratory animals, but not in domestic animals. Together with other emerging data on the secretory activities of the feline placenta, our study underlines its relevance in the production of molecules long known to be involved in appetite control and, probably, with potential effects on the developing fetus.