Enables G protein-coupled opioid receptor activity. Acts upstream of or within adenylate cyclase-inhibiting G protein-coupled receptor signaling pathway; adult locomotory behavior; and neuropeptide signaling pathway. Located in membrane. Is integral component of membrane. Is expressed in several structures, including brain; early conceptus; genitourinary system; gut; and neural retina. Orthologous to human OPRD1 (opioid receptor delta 1). [provided by Alliance of Genome Resources, Apr 2022]