Plasma cyclic AMP hyper-response to glucagon in manic patients on lithium treatment.

We have measured the rise in plasma cyclic AMP induced by glucagon and adrenaline in manic patients on lithium therapy. Glucagon-induced increases in the concentration of plasma cyclic AMP were larger, but the adrenaline-induced increases were smaller, in lithium-treated manic patients than in normal controls. In 3 manic patients, the enhanced response to glucagon was normalized 3 weeks after the cessation of lithium treatment. Though the underlying mechanism is unknown, the unusual plasma cyclic AMP responses may reflect altered receptor sensitivity which would be closely related to the curative effect of lithium on symptoms of mania.