Leptin is small cytokine-like protein that is involved in appetite and body weight regulation. Due to increased interest in using leptin as an anti-obesity reagent, re-combinant forms of leptin have been produced for several species, including humans, mice, rats, pigs, dogs, sheep etc. The biological activities of such re-combinant proteins were determined using various in vitro or in vivo systems; however so far, no specific as-say system for rat leptin is available. Since rats are representative animal models in obesity research, the establishment of a biological assay system for deter-mining rat leptin activity has been eagerly awaited. This study describes the generation of such a system using chinese hamster ovary (CHO)-cells that were transfected with the long form of the rat leptin recep-tor isoform, OB-Rb, whereby a signal transduces and activators of transcription-sensitive luciferase reporter system is further employed to quantify the leptin-mediated signals. This system is the first rat-specific leptin bioassay system that has been reported. It is expected that this assay will be used to further quan-tify and determine leptin activity from various biologi-cal fluids and sources.

Keywords: Leptin, OB-Rb, Rat, Luciferase, Receptor.