• Platelet serotonin (5-HT) uptake was determined in 72 newly admitted, unmedicated psychiatric patients. Decreased maximum velocity (Vmax) of 5-HT uptake was present in unipolar and bipolar depressed patients as well as schizoaffective depressed patients. The apparent Michaelis constant (km) of 5-HT uptake was normal in these groups, as was Vmax and Km in manicdepressive and chronic schizophrenic patients. Treatment of depressed patients with notriptyline hydrochloride or imipramine hydrochloride increased Km significantly. There was a trend for the increase in Km in the nortriptyline-treated patients to correlate with clinical improvement. Decreased 5-HT uptake in platelets provides additional evidence for the role of 5-HT in the pathophysiologic process of some forms of depression.
Meltzer HY, Arora RC, Baber R, Tricou BJ. Serotonin Uptake in Blood Platelets of Psychiatric Patients. Arch Gen Psychiatry. 1981;38(12):1322-1326. doi:10.1001/archpsyc.1981.01780370024002