Neuropeptide systems and schizophrenia.

Schizophrenia affects approximately 1% of the world population, and the majority of pharmacologically based treatments for this disorder are ligands that interact with monoaminergic transmission. However, there is a wealth of evidence that various neuropeptides are often co-released with monoamine neurotransmitters, and that ligands acting at neuropeptide receptors modulate monoaminergic transmission as well as schizophrenia-related behaviors in preclinical animal models. Such neuropeptide systems include neurotensin, cholecystokinin, corticotropin releasing factor, neuropeptide Y, oxytocin, opioid peptides, tachykinins, thyrotropin-releasing hormone, and orexins. The purpose of this review will be to summarize the existing preclinical and clinical literature on the role of various neuropeptide systems as modulators of schizophrenia-related behaviors, and the potential of targeting these systems for the development of novel antipsychotic medications.