[Platelet serotonin in endogenous depressive patients and normal controls].

We have studied the content of platelet serotonin in 31 depressive patients free of medication and in 29 controls. The depressive patients have been selected according to clinic diagnosis and to urinary phenylethylamine (PEA) and total phenylacetic acid (PAA) values, because low levels of these two substances are for us almost a constant in endogenous depressive patients. For the control group we selected 23 out of 29 cases studied, which had all urinary PEA and PAA values within the normal range published by us previously. In this group platelet serotonin content was of 527-900 ng/10 9 platelets with a mean of 698 +/- 125 ng/10 9 platelets. In the depressive group, taking account of platelets serotonin content we could differentiate two subgroups. In a group of 19 patients we found lower values, 157-513 ng/10 9 platelets with a mean of 407 +/- 102 ng/10 9. In the other 13 patients group we found platelet serotonin levels similar to those of the control group, 552-780 ng 10 9 platelets with a mean of 658 +/- 93 ng/10 9 platelets. Accepting blood platelets as models for serotoninergic nerve terminals, we suppose that the response of depressive patients to serotonin reuptake blockers treatment should be different in both subgroups, which is at present matter of study in our laboratory.