GR 103691 is primarily utilized in research settings, particularly in the study of central nervous system disorders. It acts as a selective antagonist for certain serotonin receptors, making it valuable in understanding the role of these receptors in neurological and psychiatric conditions. Researchers employ it to investigate potential therapeutic targets for diseases such as depression, anxiety, and schizophrenia. Its application in preclinical studies helps elucidate the mechanisms of serotonin signaling and its impact on behavior and brain function. Additionally, GR 103691 is used in pharmacological experiments to assess the efficacy and safety of new drugs targeting serotonin pathways.