Alteration of platelet serotonergic mechanisms and monoamine oxidase activity in premenstrual syndrome.

Platelet uptake and content of 5-hydroxytryptamine (5-HT), platelet monoamine oxidase (MAO) activity, and plasma free and total tryptophan levels were determined in patients diagnosed with premenstrual syndrome (PMS) and in control subjects. The Vmax of 5-HT uptake and 5-HT content in platelets of PMS patients were significantly decreased during the premenstrual phase (cycle days -9 to -1) compared to control subjects. Platelet MAO activity was significantly lower postmenstrually (cycle days 5-9) in PMS patients compared to the premenstrual phase. There were no differences in plasma free and total tryptophan levels between PMS patients and control subjects during either interval. As platelets are believed to be a peripheral model for central serotonergic neurons, the results suggest that PMS symptomatology may be related to alterations in serotonergic neuronal mechanisms.