Expression of leptin and adiponectin in the rat oviduct

In mammals, the oviduct is an important source of factors that play key roles in reproductive and developmental events. The major components of oviduct fluid are oviduct-specific glycoproteins, but other proteins are synthesized and secreted by the oviduct epithelium. Leptin and adiponectin are two hormones originally identified in adipocytes that play a critical role not only in the control of energy balance and metabolism but also in diverse functions such as reproduction. This study investigates the presence and distribution of leptin and adiponectin in the rat oviduct through a combination of immunohistochemistry and reverse transcription-polymerase chain reaction techniques. Using both techniques, it has been detected that the oviduct of cycling rats expresses leptin and adiponectin. Immunoreactivity for both adipokines appears in the apical region of the secretory epithelial cells, only in the isthmus and ampulla. The immunostain is stronger in the isthmus and changes throughout the estrous cycle in the ampulla, increasing from proestrous to estrous. The results presented here are a further contribution to the identification of leptin and adiponectin produced and secreted by the oviduct epithelium, which must be taken into account for a better understanding of the reproductive events that take place in this organ.