The calcium second messenger system in bipolar disorders: data supporting new research directions.

Studies of aberrations in second messenger function may help to elucidate some of the multiple complex neurobiological alterations in bipolar affective disorders. The phosphatidylinositol and calcium ion (Ca2+) second messengers are of particular interest because of evidence of hyperactivity of these signaling mechanisms in both mania and bipolar depression and of their normalization by lithium and other mood-stabilizing treatments. Because the intracellular Ca2+ signal has a biphasic action, a single aberration could explain diverse clinical manifestations of the same illness, and a single action on the messenger could explain the biphasic actions of many treatments for bipolar disorders.