SEROTONIN RECEPTORS AND THEIR FUNCTION IN SLEEP, ANXIETY DISORDERS AND DEPRESSION

Thirty-three years ago, Gaddum and Picarelli classified the serotonin receptors in the guinea pig ileum into D and M types based on the acti vity of dibenzyline (D) and morphine (M) to block contractions of inte stinal smooth muscle caused by serotonin. The subsequent location of s pecific ligand binding sites for serotonin in the brain has led to the identification of 14 serotonin receptor sub-types in rat brain. The c loning of these receptor sub-types has been of importance in enabling them to be classified as specific-protein molecules encoded by specifi c genes. The problem now arises with regard to the linking of the chan ges in the cellular activity of the various receptor sub-types with th e plethora of behavioural changes that arise as a consequence of the a ctions of serotonin in the brain. The present review summarizes the ev idence implicating the role of specific serotonin receptor sub-types i n sleep, anxiety states, schizophrenia and depression. A summary of th e relationship between these receptor sub-types and their possible inv olvement in the aetiology of schizophrenia, depression, anxiety and sl eep disorders.