Neurotensin (NT) is a neuropeptide found in the central nervous system and gastrointestinal tract. It is closely associated with dopaminergic and other neurotransmitter systems, and evidence supports a role for NT in various neuropsychiatric disorders. Because NT is readily degraded by peptidases, our group has developed various NT agonists that can be injected systemically, cross the blood brain barrier (BBB), yet retain the characteristics of native NT. The most widely studied and successful of these compounds, called NT69L, holds promise as a therapeutic agent for Parkinson's disease, schizophrenia, psychostimulant abuse and nicotine dependence, and serves as a tool to study the cellular and molecular effects of NT.