Signaling: cellular insights into the pathophysiology of bipolar disorder.

Clinical studies over the years have provided evidence that monoamine signaling and hypothalamic-pituitary-adrenal axis disruption are integral to the pathophysiology of bipolar disorder. A full understanding of the pathophysiology from a molecular to a systems level must await the identification of the susceptibility and protective genes driving the underlying neurobiology of bipolar disorder. Furthermore, the complexity of the unique biology of this affective disorder, which includes the predisposition to episodic and often progressive mood disturbance, and the dynamic nature of compensatory processes in the brain, coupled with limitations in experimental design, have hindered our progress to date. Imaging studies in patient populations have provided evidence of a role for anterior cingulate, amygdala, and prefrontal cortex in the pathophysiology of bipolar disorder. More recent research strategies designed to uncover the molecular mechanisms underlying our pharmacologic treatments and their interaction in the regulation of signal transduction as well as more advanced brain imaging studies remain promising approaches. This experimental strategy provides data derived from the physiologic response of the system in affected individuals and addresses the critical dynamic interaction with pharmacologic agents that effectively modify the clinical expression of the pathophysiology.