Neurotensin is a 13-amino-acid peptide hormone present in the central nervous system and gastrointestinal tract. It functions as a neurotransmitter in the brain, a hormone in the gut, and a neuromodulator. It is involved in the pathophysiology of several CNS disorders, including schizophrenia, Parkinson's disease, drug abuse, pain, cancer, inflammation, eating disorders, and central control of blood pressure, due to its interaction with multiple neurotransmitter systems such as dopaminergic, serotonergic, glutamatergic, GABAergic, and cholinergic systems. It acts as a human metabolite, mitogen, neurotransmitter, and vulnerary. It is the conjugate base of neurotensin(1+).