The present invention relates to compositions and methods for treating neuropsychiatric disorders in vertebrates and humans. More specifically, the present invention provides for use of IRL-1620, an endothelin-B receptor agonist, in appropriate doses to be a neuroprotective and a neuroregenerative agent. Accordingly, in one aspect the disclosure provides a method of treating a neuropsychiatric disorder comprising administering to a patient in need thereof a therapeutically effective amount of an endothelin-B receptor agonist to treat the neuropsychiatric disorder. In some embodiments, the endothelin-B receptor agonist is co-administered with an additional agent to treat the neuropsychiatric disorder. In some embodiments, the additional agent is selected from the group consisting of an antidepressant, an anti-inflammatory agent, a CNS stimulant, a neuroleptic, and an anti-proliferative agent.
