Second, neuropeptides involved in arousal, including galanin and proenkephalin, appear to be more highly expressed in the anterior PVT; those involved in depression-like behavior, including tachykinin 2, cholecystokinin, and CRH, are more highly expressed in the posterior PVT; those involved in reward, including tachykinin 2 and cocaine- and amphetamine-regulated transcript, are more highly expressed in the medial PVT; but those involved in the intake of food and drugs of abuse are distributed throughout the PVT. This evidence concerns the gene CCK and major depressive disorder.