Different effect of desipramine on protein kinase C in platelets between bipolar and major depressive disorders

Protein kinase C (PKC) activity was investigated in platelets from affective disorder subjects and healthy volunteers. The PKC activity of platelets incubated with desipramine was determined in vitro. The PKC activity of the major depressive disorder subjects and healthy volunteers was inhibited by desipramine, whereas that of the bipolar disorder subjects showed both inhibition and activation. In addition, the base PKC activity incubation with antidepressants of the major depressive disorder patients was significantly higher than of the bipolar disorder patients. These preliminary results suggest that the function of PKC may, at least in part, be associated with the mechanism of affective disorder.