ALTERAZIONI DEL TRASPORTATORE DELLA SEROTONINA IN PIASTRINE E LINFOCITI DI PAZIENTI CON DISTURBI PSICOTICI

Given the controversial data on the role of the serotonin (5-HT) transporter in psychosis, our study aimed to investigate this structure by means of the measurements of the reuptake kinetics and of the protein density, in both platelets and lymphocytes of patients with different psychotic disorders. Twenty-five patients suffering from bipolar 1 disorders with mood incongruent psychotic features (14), mixed states (7) and schizophrenia (4), according to DSM-IV criteria, were included in the study and compared with a matched group of healthy control subjects. The severity of the symptoms was assessed by means of the Brief Psychiatric Rating Scale (BPRS). Platelet and lymphocyte membranes were prepared according to standardized protocols, as were carried out 3H-5HT re-uptake and 3H-paroxetine (3H-Par) binding. As far as platelet markers were concerned, Bmax values were lower, to a statistically significant degree, in patients than in control subjects (853±140 vs 1368±172, respectively, p=0.016), with no change in the Kd values (0.10±0.05 vs 0.09±0.03). The Vmax values (pmol/109 plt/min, mean+SD) too, were statistically lower in patients than in control subjects (52±18 vs 133±15, respectively, p=0.03) while the Km values were 161±62 in patients and 211±67 in control subjects. The same results were obtained in lymphocytes, namely the Bmax (313±131 vs 600±50, p=0.008) and Vmax (7400±310 vs 9400±350, p=0.016) values were statistically lower in patients than in the control subjects, with no change in the Kd or Km (0.08±0.02 vs 0.12±0.03 and 195±49 vs 180±67, respectively). No correlation was observed between biological markers and either the psychopathological scale total score or single items. The results of this study showed a decreased density of the 3H-Par binding sites coupled with a reduced velocity of 3H-5-HT reuptake in both platelets and lymphocytes of psychotic patients, as compared with healthy control subjects. These findings would suggest a general abnormality of the 5-HT system in psychotic patients.