Cholecystokinin and Psychiatric DisordersRole in Aetiology and Potential of Receptor Antagonists in Therapy

Cholecystokinin (CCK) is one of the most abundant neuropeptides in the brain. It is found in the highest levels in cortical and limbic structures and also in the basal ganglia. Two subtypes of CCK receptors have been described in the brain and gastrointestinal tissues. CCKA (alimentary subtype) receptors are mainly located in the gastrointestinal tract, regulating secretion of enzymes from the pancreas and emptying of the gallbladder. However, CCKA receptors are also found in several brain regions, with the highest densities in structures poorly protected by the haematoencephalic barrier (the area postrema, nucleus tractus solitarius and hypothalamus). The distribution of CCKB (brain subtype) receptors overlaps with the localisation of CCK and its mRNA in different brain areas, with the highest densities in the cerebral cortex, basal ganglia, nucleus accumbens and forebrain limbic structures.