Increased platelet membrane [3H]‐LSD binding in patients on chronic neuroleptic treatment.
British Journal of Clinical Pharmacology – April 01, 1985
Source: OpenAlex
Summary
Schizophrenic patients treated with depot thioxanthenes and phenothiazines exhibit a notable 30% increase in platelet 5-HT receptor numbers compared to controls. However, their receptor affinity decreased by approximately 30%. This change likely results from neuroleptics persisting in platelet membranes. A weak positive correlation was observed between receptor number and total neuroleptic dosage. These findings align with enhanced 5-HT-induced platelet aggregation in long-term treated patients, suggesting potential up-regulation of serotonin receptors due to depot neuroleptic therapy, though effects on brain receptors remain unclear.
Abstract
Using a [3H]‐lysergic acid diethylamide [(3H]‐LSD) binding technique, platelet 5‐hydroxytryptamine (5‐HT) receptor number and affinity were compared in schizophrenics treated with depot thioxanthenes and phenothiazines and controls. There was an approximately 30% increase in platelet receptor number (Bmax) in the patient group. There was a decrease in affinity (increase in Kd) of about 30% in the patient group. This was probably due to the persistence of the neuroleptic in the platelet membrane preparation. There was a weak positive correlation between receptor number and total neuroleptic dosage. The increased number of 5‐HT receptors is consistent with the previously reported enhancement of 5‐HT‐induced platelet aggregation in patients treated with long‐term phenothiazines and thioxanthenes. Our findings are compatible with 5‐HT up‐regulation in human platelets produced by depot neuroleptic therapy. It is not known whether parallel changes may be occurring in brain 5‐HT receptors.