APA Dictionary of Psychology

derivatives of inositol that contain one or more phosphate groups, some of which are second messengers in cells, serving to relay signals from receptors at the cell surface to other parts of the cell. The most studied of these second messengers is inositol 1,4,5-trisphosphate (IP3). The action of lithium salts, used to treat bipolar disorders, may be linked to their inhibition of the enzyme inositol monophosphatase, which is involved in the recycling of inositol from the inositol phosphates. It has been hypothesized that this inhibition thus leads to a deficiency of inositol and a corresponding excess of inositol phosphates.