The present invention provides Orphanin FQ receptor nucleic acids and polypeptides and uses thereof. In particular, the present invention provides nucleic acid sequences of differentially expressed splice variants of the Orphanin FQ receptor. The present invention also provides methods of using the Orphanin FQ receptor nucleic acid sequences and ligands for the identification of pharmaceutical agents, the generation of animal models of Orphanin FQ receptor-mediated disease states, and for formulating biological activities. The present invention further provides improved methods of screening potential therapeutics useful in the treatment of a variety of disease states mediated by Orphanin FQ signaling, as well as therapeutics identified using the screening methods.