Differential effects of lithium on platelet protein phosphorylation in bipolar patients and healthy subjects

In the present study we have investigated the cAMP-dependent phosphorylation system in platelets of euthymic bipolar patients and healthy volunteers before and after 15 days of lithium treatment. The results showed that 15 days of lithium treatment enhanced the basal and the cAMP-stimulated ³²P incorporation in the 22 and 38 kDa phosphoproteins in bipolar patients, but not in healthy subjects. Moreover, we provided further evidence of increased phosphorylation in the 22 kDa platelet phosphoprotein in untreated euthymic bipolar patients when compared with controls. Overall, these findings suggest an implication of protein phosphorylation in the biochemical action of lithium and in the pathophysiology of bipolar disorder. Received: 9 April 1996/Final version: 1 September 1996