Guanylyl cyclase-C (GC-C) is an intestinal membrane receptor protein that has long been known to play an important role in diarrheal disease and other intestinal functions, but recent research has found that it is also linked to neuropsychiatric disorders.

In addition to its home in the gut, researchers working with mice have discovered that the GC-C receptor is also expressed in midbrain neurons, a region of the central nervous system that is associated with vision, hearing, motor control, sleeping and waking, alertness and temperature regulation. The GC-C signaling pathway in the brain plays a role in controlling behavior and responding to the neurotransmitter dopamine; in the mouse study, GC-C activation increased brain dopamine levels and deleting the GC-C receptor caused reduced dopamine levels and related behavioral problems.

Dopamine regulates a number of important brain functions, and dysfunctional dopamine neurons are associated with neuropsychiatric disorders like ADHD and schizophrenia. GC-C's role in the function and balance of the dopamine system could make it a good target for new treatments for disorders like schizophrenia, ADHD, Parkinson's disease, and addiction.