PZ-2891 is primarily used in research settings as a selective antagonist for the GPR139 receptor, which is implicated in various neurological and psychiatric conditions. It serves as a pharmacological tool to study the function and signaling pathways of GPR139 in cellular and animal models. Due to its ability to cross the blood-brain barrier, it is valuable in central nervous system research, particularly in exploring potential roles in mood regulation, schizophrenia, and Parkinson’s disease. Its application is currently limited to preclinical investigation and is not used in clinical or industrial settings.