Adrenaline-induced platelet aggregation in depressed patients and control subjects

We measured alpha 2-adrenoceptor-mediated platelet primary aggregation in depressed patients and healthy subjects. Both initial velocity and maximum amplitudes of platelet response to increasing concentrations of adrenaline were decreased in drug-free depressed patients as compared with controls. The EC50 of both initial slope and maximum amplitude were also increased in drug-free depressed patients. The results suggested a lowered platelet alpha 2-adrenoceptor function. Demographic factors (age and sex) and the time between blood collection and start of aggregation monitoring did not influence the results. This report is consistent with postsynaptic receptor desensitization in depressed patients. The precise molecular mechanism for this impairment remains to be elucidated.