Effects of lithium administration on plasma catecholamines.

The mode of action of lithium in the treatment of bipolar affective disorder is unknown. Among its actions are effects on release and response to catecholamines in experimental animals. We have therefore examined its effect on peripheral catecholamines in man. After 3 weeks of administration of therapeutic doses of lithium carbonate, healthy volunteers showed a differential response of catecholamines to insulin stimulation. Although the response of plasma norepinephrine remained unchanged, epinephrine response was dramatically reduced. These findings provide additional evidence for the separate neural regulation of the adrenal medulla and sympathetic nerve endings. Further studies are necessary to determine whether these effects on peripheral epinephrine are paralleled by changes in central epinephrine.