The present invention provides Orphanin FQ receptor nucleic acid sequences. Specifically, 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 for the identification of pharmaceutical agents and the generation of animal models of Orphanin FQ receptor-mediated disease states. The present invention thus provides improved method of screening potential therapeutics useful in the treatment of a variety of disease states mediated by Orphanin FQ signaling.