MRNA expression and immunocytochemical localization of leptin receptor in the oviduct of the laying hen (Gallus domesticus).

The role of leptin in female reproduction is fairly well established in mammals, whereas reports concerning leptin action in birds are scarce. The aim of the present study was to detect leptin receptor (LEP-R) mRNA and to localize the leptin receptor protein in the oviduct of laying hens 2h after ovulation by the RT-PCR method and immunocytochemical staining. The RT-PCR reaction demonstrated expression of the long form ofleptin receptor mRNA in all examined oviductal parts (infundibulum, magnum, isthmus and shell gland) and the weakest level was found in the isthmus. The expression of the short isoform was lower than the long form in all examined tissue samples and no differences between oviductal parts were observed. Immunostaining specific for leptin receptor was found in the walls of all examined oviductal parts. The intensity of the immunopositive reaction was the strongest in the epithelium of all examined parts of the oviduct and in the endothelium and muscles of blood vessels. The weakest immunopositive reaction was observed in tubular glands, the connective tissue layer and in circular and longitudinal muscles. The results obtained in this experiment suggest that the oviduct may be a target tissue for leptin, where this polypeptide hormon may participate in egg formation and/or its transport through the oviduct of the domestic hen.